Artificial Intelligence hardware accelerators are pervading the chip market. Most of the time, they are third-party IPs integrated by silicon manufacturers. As a consequence, their design may be obfuscated, which can introduce issues from a manufacturing testing perspective. This paper illustrates how to effectively and efficiently select the most appropriate functional stress stimuli for Artificial Intelligence (AI) Hardware (HW) Accelerators embedded in System-on-Chip (SoC). The proposed methodology is netlist independent; and it is based on both current measurements from the real chip and architectural evaluations. These ingredients are heuristically used to rank and sift the optimal functional patterns to apply along the Burn-In (BI) phase. Experimental results on two different Automotive SoCs manufactured by STMicroelectronics, demonstrate the effectiveness and efficiency of the proposed method.

In modern automotive system-on-chip (SoC) designs, large embedded flash memories have become a standard feature. Since they occupy a significant percentage of the die area, their impact on the SoCs’ overall yield is substantial, making them a critical component in the production process. Embedded memories are then deeply tested to unsure their reliability. The data collected through these tests are fundamental to chip designers and test engineers to iron out their designs and understand the most common failure mechanisms. A common approach for data collection is the generation of bitmaps based on the gathering of individual fail coordinates in a list-based fashion. Other more efficient compaction or compression approaches exist and all these approaches can use dedicated internal memories to store the result of a given test. Unfortunately, all the methods currently found in the literature do not allow diagnostic data retention along multiple tests, requiring constant and time-consuming communications with the external tester, increasing the test cost for the manufacturers. This article presents an on-chip algorithm to compact and retain diagnostic information from multi-step embedded memories testing. The foundation of this work lies in an efficient shape recognition and encoding algorithm. The collected information is stored in a dedicated nonvolatile on-chip memory. Information about the tests that generated a given set of fault shapes is also encoded in this dedicated diagnostic memory, enabling manufacturers to collect all the diagnostic information at the end of their test flow. Experimental results on over 110 Automotive SoCs made by Infineon TM show that using the proposed approach, 100% of the diagnostic information of devices undergoing a standard automotive-grade test flow is permanently encodable in a limited 24 KB diagnostic space while also consistently reducing the total test time of up to 53.8% with respect to traditional list-based approaches.

Embedded memories are an essential component of modern System-on-Chips (SoCs). As memory requirements are constantly increasing, embedded memories occupy a significant percentage of the die area and are one of the main contributors to the yield of the devices. Manufacturers must conduct thorough testing to assess the reliability of their products, particularly in safety-critical environments like automotive applications. A typical automotive-grade memory test flow comprises several tests under varying conditions, including temperature and operating frequency. The SoC under test executes these tests, and they typically generate an extensive amount of diagnostic data that needs to be exported to the external world in time-consuming communications with the external testers. The computationally easiest way to encode the diagnostic data is through a list-based method, in which each single fault is logged individually, but is not particularly efficient with huge number of faults. This paper presents an optimized on-chip fault encoding algorithm that combines an efficient fault shape encoding method with only the encoding of the differences between each test. Experimental results collected in a simulation environment, where 10,000 devices were modeled to realistically represent fault evolution between consecutive memory tests, demonstrate an average reduction of 66.99% in diagnostic memory space requirements compared to previous State-Of-The-Art (SOTA) solutions.

The IEEE European Test Symposium (ETS) has been facilitating progress in electronic systems testing since its launch in 1996. On the occasion of its 30th anniversary, this collaborative paper gathers sections by 21 ETS teams to outline their influential ideas and milestones. Each team’s section highlights historical perspective, current research, frameworks and projects as well as forward-looking research agendas in the area of electronic-based circuits and systems testing, reliability, safety, security and validation. This anniversary summary documents how research of various ETS teams, exemplifying the test community, has been evolving and transitioning from concepts to practical standards and Electronic Design Automation (EDA) tools and flows. This legacy is a strong base to drive the next generation of advances in electronic systems testing.

As the industry advances towards smaller geometries for integrated circuits (ICs), internal cell defects have become increasingly crucial to address. Cell-Aware Testing (CAT) has emerged as the industry standard for achieving the high-quality levels required in modern ICs, as it explicitly targets intra-cell defects. However, the comprehensive defect coverage provided by CAT can result in a high test pattern count, which directly impacts test time and production costs.This paper proposes two complementary methodologies to optimize the cell library characterization phase by leveraging weak detections to maximize the number of Don’t Cares (DCs) and equivalent defects. The proposal produces an optimized Defect Detection Matrix (DDM) for the library, which is then used by the ATPG for pattern generation at the design level.The methodologies have been validated by running CAT ATPG for five different designs, using a 65nm cell library characterized with the proposed approach. The experimental results show that using the optimized DDMs reduces the number of patterns by an average of 8% and the pattern generation time by 11%, depending on the methodology used and the circuit analyzed.

Traditional structural tests do not provide comprehensive coverage of all possible faults in automotive System-on-Chips (SoCs). To address these gaps, the manufacturing test flow now incorporates System-Level Test (SLT), an additional holistic test phase that executes advanced functional test programs. This research advances SLT methodologies by introducing a stress-optimization approach that targets critical, non-uniformly stressed areas, complementing structural stress methods. It also provides practical guidelines for developing SLT suites that effectively test SoC communication peripherals. Additionally, automated SLT workload generation techniques leverage graph-based SoC abstractions and Device Tree Source (DTS) files to reduce manual effort. Furthermore, grading methodologies are proposed to evaluate SLT effectiveness using high-level metrics derived from instruction traces, enabling early feedback without exhaustive fault simulation. The proposed methods are validated on a 40nm automotive SoC, manufactured by STMicroelectronics, with approximately 20 million logic gates, using a low-cost, FPGA-based modular tester. Experimental results demonstrate that SLT suites can significantly enhance the quality and reliability of automotive SoCs. Collectively, these contributions make SLT more scalable, automated, and effective, meeting stringent automotive quality standards and enabling broader application in domains such as data center processors.

Nowadays, AI applications are becoming extremely popular in our everyday life as well as for the industry. Recent incidents involving hyperscalers have revealed that even cloud-based datacenter hardware can experience failures leading to Silent Data Corruptions (SDCs), also called Silent Data Errors (SDEs). This Special Session delves into the implications of such failures on AI workloads, both during training and inference, and explores methodologies for efficiently detecting SDCs or SDEs through dedicated monitoring phases.

Developing functional test programs for hardware testing is time-consuming and experience-wise. A functional test program’s quality is usually assessed only through expensive fault simulation campaigns during early development. This paper presents indirect quality measurements of fault detection capabilities of functional test programs to reduce the total cost of fault simulation in the early development stages. We present a methodology that analyzes the instruction trace generated by running functional test programs on-chip and building its control and dataflow graph. We use the graph to identify potential flaws that affect the program’s fault detection capabilities. We present different graph-based techniques to measure the programs’ quality indirectly. By exploiting standard debugging formats, we individuate instructions in the source code that affect the graph-based measurements. We perform experiments on an automotive device manufactured by STMicroelectronics, running functional test programs of different natures. Our results show that our metric allows test engineers to develop better functional test programs without basing their development solely on fault simulation campaigns.

This paper deals with functional System-Level Test (SLT) for System-on-Chips (SoCs) communication peripherals. The proposed methodology is based on analyzing the potential weaknesses of applied structural tests such as Scan-based. Then, the paper illustrates how to develop a functional SLT programs software suite to address such issues. In case the communication peripheral provides detection/correction features, the methodology proposes the design of a hardware companion module to be added to the Automatic Test Equipment (ATE) to interact with the SoC communication module by purposely corrupting data frames. Experimental results are obtained on an industrial, automotive SoC produced by STMicroelectronics focusing on the Controller Area Network (CAN) communication peripheral and showing the effectiveness of the SLT suite to complement structural tests.

Traditional structural tests are powerful automatic approaches for capturing faulty behavior in integrated circuits. Besides the ease of generating test patterns, structural methods are known to be able to cover a vast but incomplete spectrum of all possible faults in a System-on-Chip (SoC). A new step in the manufacturing test flow has been added to fill the leftover gaps of structural tests, called the System-Level Test (SLT), which resembles the final workload, and environment.This work illustrates how to build up an automated generation engine to synthesize SLT programs that effectively attack structural test weaknesses from both a holistic and an analytical perspective. The methodology targets the crossbar module, as one of the most critical areas in the SoC, and it simultaneously creates a ripple effect across the un-core logic.Experimental results are conducted on an automotive SoC manufactured by STMicroelectronics.

This paper explores the trade-offs of reducing scan test patterns during Wafer Sort, accepting additional packaging costs, and screening more chips during Package Tests. Previous works proposed ways of selecting or reordering patterns to bring the most efficient to the left. Unlike such studies, this work quantifies the benefit of removing patterns directly from the tail of any pattern set. The paper elaborates on novel formulas to propose a comprehensive cost model that combines yield, Wafer Sort, packaging, and Package Test costs. The model evolves from known concepts by assuming that mass production defectivity is non-uniformly distributed over the die population and accounts for sacrificial lots to extract guiding information. It is shown that reducing patterns at Wafer Sort is beneficial under certain conditions of yield, fault coverage, and considering equipment and production costs. The model accurately estimates the number of patterns to remove for maximum gain in these cases. As a further by-product, the paper shows that a significant cost advantage can be achieved if pattern generation is guided based on the basics of the non-uniform failure distribution. This approach is validated with an academic benchmark and by observing six months of production for a real-world microcontroller by STMicroelectronics.

The rising complexity of integrated devices has led to new defect types and failure modes at the system level that are not detected by structural tests. System-Level Test (SLT) is another test step to combat this challenge. SLT is in charge of exercising system-level interactions between hardware components and software. Non-functional properties, e.g., temperature, play a major role in SLT.This work focuses on the automatic generation of assembly test programs for SLT that aim to indirectly maximize a particular non-functional property, for example, the temperature. It is based on two-step generation with genetic algorithms. First, a fast architectural simulation is used with the genetic algorithm to provide a structure for the test programs. Afterward, an additional generation is done on the hardware to optimize the initial register contents of the program.The case study for gathering experimental results is a super-scalar out-of-order RISC-V processor, the Berkeley Out-of-Order Machine (BOOM). Experimental results show that the two-step generation is more effective in converging to a better power-hungry test program than only using the power consumption as a fitness function for the genetic algorithm.

Embedded nano-electronic devices have spread in daily life over the past ten years. Chip and embedded system manufacturing has thus become more challenging in recent years.When safety-critical sectors like the automobile are considered, addressing system anomalies and faults is crucial. Therefore, it is necessary to develop and research innovative ways to maintain high reliability in safety-critical sectors despite the complexity of present Systems-on-Chip (SoCs).In order to ensure high reliability, and be compliant with reliability standards, designers started to add additional circuitry to perform on-device tests. Built-In-Self-Test (BIST) is a technology that allows to conduct exhaustive tests within devices and, most importantly, without the need for external equipment. BIST can detect faults by outputting a signature at test end, which can be compared with a known value. Thus such known signatures are key, and in case of a signature mismatch it is not trivial to understand the root cause of the failure.This paper proposes a methodology to find the first failing pattern which causes the BIST’s signature to deviate and a way to collect good signatures from in-field devices, at key on/off, where BISTs are programmed and executed by the firmware at maximum frequency for an industrial case study produced by STMicroelectronics.The transition delay fault model is the primary target for the described work.

Electronics play a significant role in modern society in various areas of our daily lives. Companies producing embedded nano-electronic systems have responded to the ever-increasing demand for high-performance chips with the development and production of structurally complex design, both in terms of the number of gates they are composed of and how they are arranged on the silicon surface. Especially devices intended for safety-critical fields, such as the Automotive field, require a thorough and precise testing process before they are fielded. This paper proposes a correlation analysis between candidate faulty logical gates as possible sources of a given failure identified during the Manufacturing Test Flow and their layout characteristics on the silicon. It is meaningful feedback for manufacturers about the quality of their applied tests. The experimental results are reported for data regarding a production lot of an Automotive System-on-Chip belonging to the SPC58 family produced by STMicroelectronics.

With the capability improvements in modern Systemon-Chips (SoCs), the complexity of SoCs is increasing. Thus, manufacturers are investing heavily in designing and testing their devices. This complexity is causing a continuous expansion in the size of embedded memory structures. As a result of the shrinking dimensions of the transistors, memories are increasingly susceptible to Multiple Bit Upsets due to cosmic radiations.Testing memories requires more details about the internal hardware configurations. However, these details are not provided to the final customer, who is left with inexplicable effects.This paper proposes a new method to reconstruct architectural details from embedded SoC memories. This method extracts memory design parameters from Multiple Bit Upsets (MBUs) generated through a single irradiation test. The algorithm was tested on around 5,500 randomly generated memories. Each memory was injected with 100 Multiple Event Upsets (MEUs). The algorithm was set to test for each memory 20, 40, 60, 80, and 100 MEUs to validate the proposed approach. Alongside the correct memory design configuration (MDC), the algorithm found other possible MDCs. The quantity of these equivalent configurations decreased with the increment of the considered MEUs. This number decreased to an average of 2 equivalent MDCs when considering 100 MEUs.

Functional test programs are increasingly used as flexible approaches to verify device functionality, both online (e.g., Software-Based Self Tests encapsulated in Software Test Library) and during the manufacturing test flow (e.g., System-Level Test). However, a traditional integrated development environment seldom analyzes functional test program weaknesses regarding fault-masking and propagation in CPU registers. Therefore, understanding the presence of errors in the programs due to logic faults at the end of the test program is only assessed by a signature computation, e.g., xor operation between all registers. The presence of program weaknesses in terms of data or control flow is not assessed, and it may lead to fault escapes and/or masking. In particular, those are perfect conditions for proliferating Silent data corruption and unrecoverable errors at the system level.This work aims to introduce a guided debugger-based fault injector framework to verify the fault propagation and masking capabilities of functional test programs by eventually catching program errors without relying on time-consuming simulation-based approaches. The fault-free instruction trace is dumped and analyzed to provide information about possible target registers of specific instructions for injecting faults, e.g., in jump instructions, where errors into registers may change the execution flow or not, to verify the presence of silent data corruptions and errors.The experimental results are carried out on an automotive device from the SPC58 family manufactured by STMicroelectronics, and faults are injected through a script running on Power Debug E40 from Lauterbach.

Burn-In test equipment usually owns extensive memory capabilities to store pre-computed patterns to be applied to the circuit inputs as well as ad-hoc circuitries to drive and read the DUT pins during the BI phase. The solution proposed in this paper dramatically reduces the memory size requirement and just demands a generic microcontroller unit (MCU) equipped with a couple of embedded processors, some standard common peripheral units, and a few KB memories. Moreover, the proposed Burn-In tester could be integrated into a System Level Test equipment which is typically based on MCUs to communicate functionally with the DUT. This paper provides full details about the architecture of such a low-cost innovative tester, which can supply the DUT with unlimited pseudo-random patterns created autonomously by the MCU firmware from any selected seed. The tester prototype developed to collect experimental results includes a low-cost System-on-Chip based on a multi-core MCU and a set of peripheral cores, encompassing timers and Direct Memory Access modules. The tester prototype is used to stress an automotive chip accounting for about 20 million gates, 700 thousand scan flip-flops, and several scan modes. The combination of pseudo-random pattern generation with the ability to control different scan and Design for Testability (DfT) modes, including LBIST, permits to reach a higher coverage of stress metrics than by the application of a limited set of pre-computed ATPG patterns. The toggle coverage level reached is up to 95.89%. The application speed achieved by the tester with non-optimized connections is up to about 10MHz.

This paper encompasses three contributions by industry professionals and university researchers. The contributions describe different trends in automotive products, including both manufacturing test and run-time reliability strategies. The subjects considered in this session deal with critical factors, from optimizing the final test before shipment to market to in-field reliability during operative life.

The complexity of automotive Systems-on-a-Chip (SoCs) has enormously grown in the last decades. Today’s automotive SoCs are compelling due to technology improvements, different integration technologies, increased heterogeneity, and many available embedded memories. On balance, despite testing techniques that have been refined through years, traditional structural test methods, like scan and BIST, can cover a vast but not complete spectrum of all the possible defects. It appears that the divide-and-conquer approach founded on structural techniques may not be enough to reach every single element or to effectively stimulate the faulty behaviors that may show up during the lifetime of the device. Burn-In is widely used to reduce Infant Mortality, accelerating the evolution of weak points into defects via externally or internally induced stress.In this work, we focus on internal stress and present a generation strategy intended to automatically produce functional stress procedures for the Burn-In phase that exacerbate possible weak points which are likely to escape activation by structural tests, such that they more easily outbreak during the successive final test procedures. The proposed generation strategy primarily addresses the interconnections to embedded memories, which look challenging to stress by structural methods, including Logic and Memory BIST, and critical due to the integration of different technologies (i.e., logic gates and memory layout). In the considered test case, the proposed approach increases the average toggle activity by orders of magnitude with respect to Memory BIST. Furthermore, it provides a uniform distributed toggling activity.Results collected on an automotive SoC show how the stress provided by functional programs compares with the stress level provided by structural test methods measured in terms of toggling activity. The SpeedUp produced by the proposed procedure is 3.14X wrt to the MBIST executing the March C-algorithm.

Embedded memories in Automotive Systems-on-Chip usually occupy a large die area portion. Consequently, their defectivity can strongly impact production yield for any automotive device. Along with the technology ramp-up phase and for statistical process control reasons during volume production, it is a good automotive industry practice to collect diagnostic information in addition to pure testing data. Designers and technology experts must receive accurate diagnostic results from failing devices to react to misbehavior by identifying and correcting the related issues at their source and drawing correct repair strategy conclusions. A commonly used approach resorts to the generation of failure bitmaps based on collecting all failing bits coordinates to be sent one by one to the tester. More efficiently, the encountered faults can be compacted or compressed in on-chip memory resources to be retrieved by the tester at the end of the memory test.This paper presents an on-chip method to compact diagnostic information during embedded memory testing. More specifically, the method is applied to diagnose embedded FLASH memories. This strategy permits the reconstruction of failure bitmaps without any loss, while compression approaches obtain an approximation. The proposed method uses a fraction of the memory requested by a coordinate-based bit mapping approach and is comparable to compression methods. At the cost of a moderate test time overhead, the proposed strategy permits dramatically increasing the number of devices that can be fully diagnosed without any bitmap reconstruction loss. Most failing devices in a real embedded FLASH production scenario were diagnosed after a single transfer from on-chip to the tester host computer.

Electronics employed in modern safety-critical systems require severe qualification during the manufacturing process and in the field, to prevent fault effects from manifesting themselves as critical failures during mission operations. Traditional fault models are not sufficient anymore to guarantee the required quality levels for chips utilized in mission-critical applications. The research community and industry have been investigating new test approaches such as device-aware test, cell-aware test, path-delay test, and even test methodologies based on the analysis of manufacturing data to move the scope from OPPM to OPPB. This special session presents four contributions, from academic researchers and industry professionals, to enable better chip quality. We present results on various activities towards this objective, including device-aware test, software-based self-test, and memory test.

Testing and validation check a hardware device or a software application against the desired design requirements. They are a vital part of all steps of system engineering and typically account for a significant percentage of the overall development cost. This paper presents a novel technique to provide a quick preliminary evaluation of functional test procedures of various natures, ranging from Software-Based Self-Test to Burn-In Functional Stress and System-level tests. We define a new metric called “connectivity”, which is fast to compute and can be used to guide functional program development. The method does not require logic or fault simulations, and it is based on the analysis of the execution trace generated by the functional program. To summarize our process, we first obtain the trace directly from the chip, running the software through a debugger. Then, we create a graph representation of the program data flow. Finally, we analyze the graph to identify instructions that negatively impact the final coverage. We perform experiments on an automotive device manufactured by STMicroelectronics, and we demonstrate the effectiveness of the approach in terms of computation time and beneficial effects on the fault coverage.

With the explosion of off-the-shelf SoCs in terms of size and the advent of novel techniques related to failure modes, commercial ATPG and fault simulation engines can often be insufficient to measure the coverage of very specific metrics. In these cases, many researchers firstly store the simulation trace during the analysis phase. Then, they collect the desired statistics during a post-processing step. In this framework, the so-called Value Change Dump (VCD) is a very commonly used file format to record simulation traces. The target of this paper is twofold. From the one hand, we illustrate some Burn-In (BI) related metrics which cannot be evaluated by current commercial fault simulators and ATPG engines. These metrics are indeed based on a post-processing analysis of memory dumps in VCD format. From the other hand, we mitigate the evaluation time and the memory required to analyze huge VCD files by exploiting optimization techniques coming from modern programming features and smart parallelization. Adopting this strategy, we can analyze simulation dumps of more than 250 GBytes in less than one hour, showing improvements of two orders of magnitude over previous tools, with a consequent higher scalability and testability power.

System-level test (SLT) is gaining in importance in modern test flows. This paper summarizes recent industrial findings from three companies and discusses some of the still open questions. The first two reports focus on the optimization potentials due to defect coverage overlaps between SLT and other test insertions. Results observed on approximately 20 million manufactured 28nm and 40nm automotive system-on-chip (SoC) designs are reported. Costs and benefits of SLT are discussed and the potentials of a test results analytics platform are identified. The third report explores the role of marginalities among SLT fails. The post-silicon investigation of a CPU block in a 7nm 5G mobile SoC product aims at achieving a better understanding, whose fails are due to random variations versus systematic factors.

System-level test, or SLT, is an increasingly important process step in today's integrated circuit testing flows. Broadly speaking, SLT aims at executing functional workloads in operational modes. In this paper, we consolidate available knowledge about what SLT is precisely and why it is used despite its considerable costs and complexities. We discuss the types or failures covered by SLT, and outline approaches to quality assessment, test generation and root-cause diagnosis in the context of SLT. Observing that the theoretical understanding for all these questions has not yet reached the level of maturity of the more conventional structural and functional test methods, we outline new and promising directions for methodical developments leveraging on recent findings from software engineering.

The introduction of System Level Test (SLT) about a decade ago aimed to a better sustainability for the achievement of the quality objectives required by high performances GPUs and CPUs. The paper intends giving some quantitative information to support this simplified statement. To do this we will report the results of a study conducted by the industrial application of SLT on a product targeted to a high-quality market segment, such as automotive. The discussion will describe the different SLT solutions developed for this new field of application and how it was possible to isolate SLT-only fails and relative functional root causes and cross-correlate traditional ATE test versus SLT screening capability through manufacturing operations.

Today, safety-critical applications require self-tests and self-diagnosis approaches to be applied during the lifetime of the device. In general, the fault coverage values required by the standards (like ISO 26262) in the whole System-on-Chip (SoC) are very high. Therefore, different strategies are adopted. In the case of the processor core, the required fault coverage can be achieved by scheduling the periodical execution of a set of test programs or Software-Test Library (STL). However, the STL for infield testing should be able to comply with the operating system specifications without affecting the mission operation of the device application. In this paper, the most relevant problems for the development of the STL are first discussed. Then, it presents a set of strategies and solutions oriented to produce an efficient and non-intrusive STL to be used exclusively during the in-field testing of automotive processor cores. The proposed approach was experimented on an automotive SoC developed by STMicroelectronics.

Automotive systems must reach a high reliability in their electronic components. This kind of devices must undergo several tests and stress steps discovering all possible defects that could manifest during lifetime. Burn-In (BI) is a manufacturing test phase used for screening the early life latent faults that can naturally affect a population of devices. System Level Test (SLT) is increasingly adopted as one of the final steps in the testing process of complex Systems on Chip (SoCs) mimicking the operational conditions. This paper aims at describing the motivations for and the effectiveness stemming from combining SLT with BI. The key idea leverages on the development of a new step inside the test process, which reproduces the system using SLT and places the system in the worst cases by means of the BI. Moreover, the paper analyses the required tester architecture to merge SLT and BI. Finally, an industrial case by STMicroelectronics is used to demonstrate the possible cost reduction.

Nowadays, Embedded Flash Memory cores occupy a significant portion of Automotive Systems-on-Chip area, therefore strongly contributing to the final yield of the devices. Redundancy strategies play a key role in this context; in case of memory failures, a set of spare word- and bit-lines are allocated by a replacement algorithm that complements the memory testing procedure. In this work, we show that replacement algorithms, which are heavily constrained in terms of execution time, may be slightly inaccurate and lead to classify a repairable memory core as unrepairable. We denote this situation as Flash memory false fail. The proposed approach aims at identifying false fails by using a Machine Learning approach that exploits a feature extraction strategy based on shape recognition. Experimental results carried out on the manufacturing data show a high capability of predicting false fails.

Environmental and electrical stress phases are commonly applied to automotive devices during manufacturing test. The combination of thermal and electrical stress is used to give rise to early life latent failures that can be naturally found in a population of devices by accelerating aging processes through Burn-In test phases. This paper provides a methodology to evaluate and compare the stress procedures to be run during Burn-In; the proposed method takes into account several factors such as circuit activity, chip surface temperature and current consumption required by the stress procedure, and also considers Burn-In flow and tester limitations. A specific metric called Stress Coverage is suggested summing up all the stress contributions. Experimental results are gathered on an automotive device, showing the comparison between scan-based and functional stress run by a massively parallelized test equipment; reported figures and tables quantify the differences between the two approaches in terms of stress.

Different perspectives about the concept of Robustness in Automotive Electronic are provides by leading edge semiconductor manufacturer. Xilinx contribution is related to the development and evaluation of Software Test Libraries suitable for in-field testing of the interconnect blocks in large SoCs. Infineon (IFX) section is discussing safety and security concerns of On-Line FLASH Memory Repair. STMicroelectronics is providing guidelines for the development and integration of Core Self-Test libraries.

In-field test of electronic devices is becoming increasingly important due to the wide adoption of electronic systems in safety-critical applications. Hence, it is crucial to devise and deploy effective solutions supporting the test during the operational phase of all the components of an electronic system, including the memory modules embedded in a SoC. Some key aspects include the possible reuse of HW infrastructures introduced for end-of-manufacturing test, the need for limited intrusiveness with respect to the application, and the achievable defect coverage. The paper discusses the main challenges in this area and possible solutions, as well as future trends.

Currently, the most of the available strategies devised for in-field testing of microprocessor cores in the automotive market, are mainly oriented to test the more representative functional modules. However, most of the modern architectures also include a series of spare computational components that perform very specific functionalities. For example, merging modules, masked and reverse operation modules, circular buffers, and special counters able to speed up the final application. In this paper, we provide a set of guidelines for the generation of Software-Based Self-Test programs that can be used to functionally test these modules during the in-field operation of the processor core. For every one of these modules, ad-hoc techniques are illustrated. The experimental results were gathered on two different multi-core designs manufactured by STMicroelectronics.

Functional test guarantees that the circuit is tested under normal conditions, thus avoiding any over-as well as under-test. This work is based on the use of Software-Based-Self-Test that allows a special application of functional test to the processor-based systems. This strategy applies the so-called functional test programs that are executed by the processor to guarantee a given fault coverage. The main goal of this paper is to investigate the static test compaction of a given set of functional test programs. The investigation aims at understanding and determining how to select the best functional test program candidates to obtain the smallest set having the best fault coverage. Results carried out on two different microprocessors show that a 49% reduction in test length and a 28.7% reduction in test application time can be achieved.

Burn-In (BI) test is usually applied in manufacturing process to screen out chip early life failures, especially for safety critical applications. Unfortunately, this test method has elevated costs for companies. In recent days, Faster-than-at-Speed-Test (FAST) has become a useful technique to discover small delay defects. At the same time, overclocking methods to enhance system performances have been studied, which focus on temperature management to preserve system functionalities. In this paper, a FAST technique is approached with the aim of intentionally provoking a thermal overheating in the microprocessor by mean of the execution of functional test programs, partly regardless of system behavior preservation. The goal is to introduce an internal stress stronger than current procedures used during BI in order to speed up early detection of latent faults. The method illustrates how to avoid blocking configurations due to timing constraints violation and leads to a significant increase of the switching activity. Experimental results on a MIPS architecture show that, by using the described technique, the processor is not falling into an unpredictable state even at frequencies up to about 20 times higher than the nominal one and the switching activity is increasing up to 300% per nanoseconds.

Thermal phenomena occurring along test execution at the final stages of the manufacturing flow are considered as a significant issue for several reasons, including dramatic effects like circuit damage that is leading to yield loss. This paper tries to redeem those bad guys in order to exploit them to improve the test quality, reducing the overall test cost without affecting the yield.

Software-Based Self-Test is an effective methodology for devising the online testing of Systems-on-Chip. In the automotive field, a set of test programs to be run during mission mode is also called Core Self-Test library. This paper introduces many new contributions: (1) it illustrates the several issues that need to be taken into account when generating test programs for on-line execution; (2) it proposed an overall development flow based on ordered generation of test programs that is minimizing the computational efforts; (3) it is providing guidelines for allowing the coexistence of the Core Self-Test library with the mission application while guaranteeing execution robustness. The proposed methodology has been experimented on a large industrial case study. The coverage level reached after one year of team work is over 87 percent of stuck-at fault coverage, and execution time is compliant with the ISO26262 specification. Experimental results suggest that alternative approaches may request excessive evaluation time thus making the generation flow unfeasible for large designs.

Self-Test strategies for testing embedded processors are increasingly diffused. In this paper, we describe a set of self-test techniques tackling dual issue embedded processors. The paper details how to produce test programs suitable to detect stuck-at faults in computational modules belonging to dual issue processors. The proposed technique is aimed at extending single issue test programs; results are illustrated for a 32-bit processor included in an automotive System-on-Chip manufactured by STMicroelectronics and implementing a dual issue strategy with static dispatch of instructions.

Functional microprocessor test methods provide several advantages compared to DFT approaches, like reduced chip cost and at-speed execution. However, the automatic generation of functional test patterns is an open issue. In this work we present an approach for the automatic generation of functional microprocessor test sequences for small-delay faults based on Bounded Model Checking. We utilize an ATPG framework for small-delay faults in sequential, non-scan circuits and propose a method for constraining the input space for generating functional test sequences (i.e., test programs). We verify our approach by evaluating the miniMIPS microprocessor. In our experiments we were able to reach over 97 % fault efficiency. To the best of our knowledge, this is the first fully automated approach to functional microprocessor test for small-delay faults.

With the continuous scaling down of the transistor size, the so-called intra-cell defects are more and more frequent. In this paper we propose a defect grading tool able to evaluate the efficiency of the applied test set. The test set efficiency is quantified w.r.t. the intra-cell defect coverage and the intra-cell diagnosis resolution.

Testing processor cores embedded in systems-on-chip (SoCs) is a major concern for industry nowadays. In this paper, we describe a novel solution which merges the SBST and BIST principles. The technique we propose forces the processor to execute a compact SBST-like test sequence by using a hardware module called MIcroprocessor Hardware Self-Test (MIHST) unit, which is intended to be connected to the system bus like a normal memory core, requesting no modification of the processor core internal structure. The benefit of using the MIHST approach is manifold: while guaranteeing the same or higher defect coverage of the traditional SBST approach, it reduces the time for test execution, better preserves the processor core Intellectual Property (IP), does not require the system memory to store the test program nor the test data, and can be easily adopted for non-concurrent on-line testing, since it minimizes the required system resources. The feasibility and effectiveness of the approach were evaluated on a couple of pipelined processors.

System on Chip devices include an increasing number of embedded memory cores, whose test during the operational phase is often a strict requirement, especially for safety-critical applications. This paper proposes a new memory test method combining the characteristics of hardware and software solutions: the test is performed by the microcontroller/processor, while the code of the test instructions to be executed is generated on-the-fly by an ad hoc module, also in charge of checking the memory behavior. The solution is modular and does not require any modification either in the memory cores or in the processor. Moreover, it is well suited to be used for test during the operational phase. Experimental results, gathered by implementing some representative March elements and algorithms, show that the method guarantees higher defect coverage than software BIST and a test time comparable with that of traditional hardware BIST solutions with a reduced hardware cost.

Functional testing of embedded processors is a challenging task and additional constraints are imposed when a functional test procedure has to be executed online. In the latter case, a significant amount of the processor faults cannot be detected since related to the debug/test circuitry or because of memory configuration constraints. In this paper we identify several sources of on-line functional untestability and propose a set of techniques to exactly measure their impact on the fault coverage. Experimental results related to an industrial case study are reported, showing that the fault coverage loss due to the considered untestability sources may reach more than 13%.

Nowadays, Software-Based Self-Test (SBST) is growing in importance especially in the on-line test scenario for safety critical systems such as automotive. This paper concentrates on the coverage by SBST of those faults in the scan chain that can impact the behavior of the embedded processor while working in its application field. A technique is described that is able to systematically tackle these faults after a scan chain analysis. Results are demonstrating the effectiveness and showing the costs of the proposed approach on a 32-bit embedded processor included in an industrial System-on-Chip used in the automotive field.

A key issue in many safety-critical applications is the test of the ICs to be performed during the operational phase: regulations and standards often explicitly describe fault coverage figures to be achieved. Functional test (i.e., a test exploiting only functional inputs and outputs, without resorting to any Design for Testability) is often the only viable solution, unless a strict cooperation exists between the system company and the device provider. However, purely functional test often shows several limitations due to the limited accessibility that it can gain on some input/output signals. This paper proposes a hybrid approach, in which a suitable hardware module is added outside a microcontroller to increase its functional testability during the operational phase. Experimental results gathered on a couple of cases-of-study are reported, showing the feasibility of the method.

High peak power consumption during test may lead to yield loss. On the other hand, reducing too much test power may lead to test escape. In order to overcome this problem, test power has to mimic the power consumed during functional mode, being as high as possible but not crossing the frontier of over-consumption. Measuring power consumption is a very time consuming activity, therefore many works in the literature focused on the indirect ways to provide power consumption estimation in a fast manner. In this paper we concentrate on a similar issue, concentrating our effort on devising a fast method for the identification and estimation of the peak power produced by test patterns. In particular we provide a detailed discussion on case studies related to peak power estimation of CPU cores when executing functional patterns, the proposed method uses the gate-level description of the CPU to identify a subset of time points over the entire test pattern that are showing the most significant peak power values. The proposed methodology has been validated on two case studies synthesized in a 65nm industrial technology.

A Branch Target Buffer (BTB) is a mechanism to support speculative execution in order to overcome the performance penalty caused by branch instructions in pipelined microprocessors. Being an intrinsically fault tolerant unit, it is hard to achieve a good fault coverage resorting to plain functional testing methods. In this paper we analyze the causes for low functional testability and propose some techniques able to effectively face these issues. In particular, we describe a strategy to perform SBST on fully associative BTB units. The unit's general structure is analyzed, a suitable test program is proposed and the strategy to observe the test responses is explained. Feasibility and effectiveness of the proposed approach are shown on a MIPS-like processor.

Software-based Self-Test (SBST) can be used during the mission phase of microprocessor-based systems to periodically assess the hardware integrity. However, several constraints are imposed to this approach, due to the coexistence of test programs with the mission application. This paper proposes a method for the generation of SBST programs to test on-line the Address Calculation Unit of embedded RISC processors, which is one of the most heavily impacted by the online constraints. The proposed strategy achieves high stuck-at fault coverage on both a MIPS-like processor and an industrial 32-bit pipelined processor; these two case studies show the effectiveness of the technique and the low effort.

This paper deals with the on-line test of SoCs including cores equipped with BIST circuitry and IEEE 1500 wrappers. A method is proposed, which exploits an Infrastructure IP named OTC to manage the on-line test, the OTC module activates the test and provides the related results under the software control of the CPU, thus allowing the SoC to autonomously and flexibly support the on-line test, both at startup and during the normal operation phase. The main advantage of the proposed method lies in the fact that the same hardware resources used for manufacturing test can be exploited for on-line test. Experimental results gathered on a case study system show the benefits and costs of the approach.

Today, electronic devices are increasingly employed in different fields, including safety- and mission-critical applications, where the quality of the product is an essential requirement. In the automotive field, on-line self-test is a dependability technique currently demanded by emerging industrial standards. This paper presents an approach employed by STMicroelectronics for evaluating, or grading, the effectiveness of Software-Based Self-Test (SBST) procedures used for on-line testing microcontrollers to be included in safety-critical vehicle parts, such as in airbags and steering systems.

This paper describes an optimized embedded memory diagnosis flow that exploits many levels of knowledge to produce accurate failure hypothesis. The proposed post-processing analysis flow is composed of many steps investigating failure shapes as well as cell fail syndromes, and includes advanced techniques to tackle incomplete data possibly due to tester noise and/or by faults showing intermittent effects. The effectiveness of the technique is demonstrated on an automotive-oriented System-on-Chip (SoC) manufactured in a 90nm technology by STMicroelectronics, which includes embedded SRAM memory cores tested using a programmable BIST. Scrambled BITMAPS gives a visual feedback leading to quick physical defect identification. Such research is relevant to aid on the manufacturing, material and process enhancements raising silicon yield.

Testing embedded microprocessors at mission time is nowadays a requirement in many SoC applications. In this paper, we introduce a methodology where the detection of operational faults is performed while the normal operations are temporarily suspended, by means of an ad-hoc HW module connected to the address, data and control buses of the microprocessor. This module behaves as a peripheral towards the microprocessor but is able to gain access to the bus over the system memory during the test. The proposed approach uses the microprocessor interrupt protocol to preserve the system state. Experimental results, gathered on a MIPS core, show the feasibility and effectiveness of the approach.

An effective silicon debug and diagnosis process has to be supported by on-chip hardware structures, stimulation equipments and software tools for analysis. In this paper, the characteristics of a software tool for memory failure analysis are presented; this tool takes into account the memory topology and the executed memory test, and returns both syndrome and shape-based failure statistics. Furthermore, it allows the cumulative analysis over many memory cuts inside a die, a wafer or a lot. The results obtained for embedded SRAMs tested using March test algorithms are presented, demonstrating the capability of the tool in underlining manufacturing process weaknesses and systematic constructive marginalities.

Volume diagnosis is crucial for discovering the root causes of yield loss during the IC production flow. This process is time consuming and requires appropriate test equipment supporting diagnostic data storage. This paper proposes a novel methodology for significantly reducing the time and the data storage requirements for digital circuit diagnosis, based on a suitable tester architecture that adapts at run-time the diagnosis process, according to a fault dictionary being a part of the diagnosis recipe. When the pattern application process reaches its end, the tester directly returns a fault hypothesis. Results obtained on the ITC99 benchmarks including full scan chains demonstrate effectiveness and efficiency of the approach. The average diagnosis time reduction achieved by using the proposed solution reaches up to 92%.

This paper proposes a programmable Built-In Self-Test (BIST) approach for DRAM test and diagnosis. The proposed architecture suits well for embedded core testing as well as for stacked and stand-alone DRAMs and it provides programmability features for executing both March and NPSF-oriented test algorithms. The proposed BIST structure is designed to be easily customized with memory topology parameters such as scrambling and mirroring, in order to automatically adapt the test circuitry to the specific memory design. Experimental results show that area overhead is negligible when considering medium-large memory cuts, while executing at-speed and Back-to-Back algorithms at more than 1GHz.

This poster outlines the working principle and an implementation of a tester architecture supporting MEMS calibration and testing; the tester works adaptively, providing electrical stimuli at run-time according to the collected results.

Critical applications based on Systems-on-Chip (SoCs) require suitable techniques that are able to ensure a sufficient level of reliability. Several techniques have been proposed to improve fault detection and correction capabilities of faults affecting SoCs. This paper proposes a hybrid approach able to detect and correct the effects of transient faults in SoC data memories and caches. The proposed solution combines some software modifications, which are easy to automate, with the introduction of a hardware module, which is independent of the specific application. The method is particularly suitable to fit in a typical SoC design flow and is shown to achieve a better trade-off between the achieved results and the required costs than corresponding purely hardware or software techniques. In fact, the proposed approach offers the same fault-detection and -correction capabilities as a purely software-based approach, while it introduces nearly the same low memory and performance overhead of a purely hardware-based one.

This paper proposes an efficient technique for transition delay fault coverage measurement in synchronous sequential circuits. The proposed strategy is based on a combination of multi-valued algebra simulation, critical path tracing and deductive fault simulation. The main advantages of the proposed approach are that it is highly computationally efficient with respect to state-of-the-art fault simulation techniques, and that it encompasses different delay sizes in one simulation pass without resorting to an improved transition fault model. Preliminary results on ITC99 benchmarks show that the gain in terms of CPU time is up to one order of magnitude compared to previous existing techniques.

Reducing the cost of test (in particular by reducing its duration and the cost of the required ATE) is a common goal which has largely been pursued in the past, mainly by introducing suitable on chip Design for Testability (DfT) circuitry. Today, the increasing popularity of sophisticated DfT architectures and the parallel emergence of new ATE families allow the identification of innovative solutions effectively facing that goal. In this paper we face the increasingly common situation of SoCs adopting the IEEE 1149.1 and 1500 standards for the test of the internal cores, and explore the idea of storing the test program on the tester in a compressed form, and decompressing it on-the-fly during test application.

Reliability testing is increasingly used not only to reduce Infant Mortality effects, but also for Reliability Characterization. This paper first discusses the characteristics of the stimuli to be used during Reliability Characterization experiments, and outlines the importance of adopting a functional approach. Secondly, the paper describes a novel approach to automatically generate suitable stress patterns to be used during the Reliability characterization process of Systems-on-chip. The generation process uses an evolutionary algorithm driven by suitable state toggling-related metrics purposely defined in the paper. Costs and benefits of the proposed approach are highlighted, supported by the results gathered on a test vehicle released on a 90 nm technology.

In this paper we present a design for reliability methodology, with the goal of reducing the impact of transistor VTHdegradation due for example to phenomena such as NBTI. It uses infrastructure IPs (I-IPs) featuring a self compensation scheme that automatically detects transistor aging effects and illustrates the design for test infrastructure used to make the SoC/System aware of the NBTI effects. This scheme is conceptually validated by using multi-level simulation and models. The discussion of possible exploitation models completes the paper.

This paper presents the results of Alpha Single Event Upsets tests of an embedded 8051 microprocessor. Cross sections for the different memory resources (i.e., internal registers, code RAM, and user memory) are reported as well as the error rate for different codes implemented as test benchmarks. Test results are then discussed to find the contribution of each available resource to the overall device error rate.

This paper proposes an efficient low-cost strategy for collecting data during radiation experiments on systems-on-chips (SoCs), exploiting the available on-chip design for testability (DfT) structures devised for manufacturing test.The approach combines hardware test and diagnostic features with suitable software tools, which enable accurate measurements and quick transient effects data collection. Specific flows for radiation testing of different kinds of embedded cores are described. Results are shown for a radiation experiment conducted on an embedded SRAM core included in a 90 nm test-vehicle.

Nanometric circuits and systems are increasingly susceptible to delay defects. This paper describes a strategy for the diagnosis of transition-delay faults in full-scan systems-on-a-chip (SOCs). The proposed methodology takes advantage of a suitably generated software-based self-test test set and of the scan-chains included in the final SOC design. Effectiveness and feasibility of the proposed approach were evaluated on a nanometric SOC test vehicle including an 8-bit microcontroller, some memory blocks and an arithmetic core, manufactured by STMicroelectronics. Results show that the proposed technique can achieve high diagnostic resolution while maintaining a reasonable application time.

Low-cost test methodologies for systems-on-chip are increasingly popular. They dictate which features have to be included on-chip and which test procedures have to be adopted in order to guarantee high test quality, while minimizing application costs. Consequently, low-cost test strategies can be run on testers offering lower performance and/or reduced features with respect to traditional automatic test equipments (ATEs); these equipments are usually referred to as low-cost testers. This paper proposes a methodology for reducing the test data volume for the application of SoC low-cost test procedures. The method exploits a tester architecture organization suitable for SoCs testing, which includes a programmable device: the usage of this configurable block joined to the analysis of test pattern regularities permits minimizing the test data volume, thus improving the tester capabilities. The proposed method relies on test pattern compression at system level and it does not address core level pattern manipulation, as several other previously published works do. Case studies are proposed, which provide data about the application of the proposed methodology to the test of SoCs including self-testable processor and memory cores. IEEE 1149.1 and IEEE 1500 test access mechanisms are considered. The achieved pattern depth reduction ratio is up to about the 64% for the considered case studies.

This paper describes a novel approach to enhance the process of reliability characterization for VLSI SoC products. To do this, we exploit Design for Test and Diagnosis structures in combination with new low-cost tester features and architecture. The main focus of our work is to obtain a modeling of the degradation of selected parameters measurable through at-speed testing. The paper reviews the current approach for reliability characterization and shows the achieved enhancement on efficiency and effectiveness. Results shown are related to experiments run on a vehicle released on a 90 nm technology.

This paper discusses the fabrication challenges introduced by products targeted to the automotive market segment. Different methods to enhance intrinsic design robustness, along with the design flow will be discussed. Experimental results from simulations and daftafom the field will be presented to support the proposed solutions.

This paper presents an innovative approach for the generation of functional programs to test path- delay faults within microprocessors. The proposed method takes advantage of both the gate- and RT-level description of the processor. The former is used to build binary decision diagrams (BDDs) for deriving fault excitation conditions; the latter is exploited for the automatic generation of test programs able to excite and propagate fault effects, based on an evolutionary algorithm and fast RTL simulation. Experimental results on a simple microcontroller show that the proposed methodology is able to generate suitable test sets in reduced times.

A large part of microprocessor cores in use today are designed to be cheap and mass produced. The diagnostic process, which is fundamental to improve yield, has to be as cost effective as possible. This paper presents a novel approach to the construction of diagnosis-oriented software-based test sets for microprocessors. The methodology exploits existing manufacturing test sets designed for software-based self-test and improves them by using a new diagnosis-oriented approach. Experimental results are reported in this paper showing the feasibility, robustness, and effectiveness of the approach for diagnosing stuck-at faults on an Intel i8051 processor core.

In this paper an agri-food traceability system based on public key cryptography and Radio Frequency Identification (RFID) technology is proposed. In order to guarantee safety in food, an efficient tracking and tracing system is required. RFID devices allow recording all useful information for traceability directly on the commodity. The security issues are discussed and two different methods based on public cryptography are proposed and evaluated. The first algorithm uses a nested RSA based structure to improve security, while the second also provides authenticity of data. An experimental analysis demonstrated that the proposed system is well suitable on PDAs too.

Delay testing is mandatory for guaranteeing the correct behavior of today's high-performance microprocessors. Several methodologies have been proposed to tackle this issue resorting to additional hardware or to software self test techniques. Software techniques are particularly promising as they resort to Assembly programs in normal mode of operation, without requiring circuit modifications; however, the problem of generating effective and efficient test programs for path- delay fault detection is still open. This paper presents an innovative approach for the generation of path-delay self-test programs for microprocessors, based on an evolutionary algorithm and on ad-hoc software simulation/hardware emulation heuristic techniques. Experimental results show how the proposed methodology allows generating suitable test programs in reasonable times.

RFID technology increases rapidly its applicability in new areas of interest without guaranteeing security and privacy issues. This paper presents a new architecture of an RFID transponder with cryptographic capabilities. Other than being compatible with the EPC Class-1 Gen-2 communication protocol, our tag implements an asymmetric ciphering module that proved useful in authentication and anti-counterfeit schemes, particularly critical in many application fields. Experimental results concerning area requirements and power consumption indicate its feasibility.

The path-delay fault simulation of functional tests on complex circuits such as current processor-based systems is a daunting task. The amount of computing power and memory needed for verifying or grading functional test programs capabilities employing traditional techniques is huge and constitutes a serious bottleneck in the test flow. In this paper we propose a new mechanism for grading functional test program path-delay coverage (1) relying on FPGA-based emulation, (2) based on suitable instrumentation of the circuit structure and (3) exploiting ad hoc modules to minimize the host performance requirements stemming from the experiment management. The proposed setup reduces the grading time by several orders of magnitude with respect to software environments. Moreover, the experimented mechanism is capable of pinpointing the clock cycles when path activation arises, thus providing a key for relating excitation conditions to the executed instructions.

The reliability of Systems-on-Chip (SoCs) is very important with respect to their use in different types of critical applications. Several fault tolerance techniques have been proposed to improve their fault detection and correction capabilities. These approaches can be classified in two basic categories: software-based and hardware-based techniques. In this paper, we propose a hybrid approach to provide fault detection and correction capabilities of transient faults for processor-based SoCs. This solution improves a previous one, aimed at fault detection only, and combines some modifications of the source code at high level with the introduction of an Infrastructure Intellectual Property (I-IP). The main advantage of the proposed method lies in the fact that it does not require modifying the microprocessor core. Experimental results are provided to evaluate the effectiveness of the proposed method.

The widespread use of cheap processor cores requires the ability to quickly point out the manufacturing process criticalities in an effort to enhance the production yield. Fault diagnosis is an integral part of the industrial effort towards these goals. This paper describes an innovative application of evolutionary algorithms: iterative refinement of a diagnostic test set. Several enhancements in the used evolutionary core are additionally outlined, highlighting their relevance for the specific problem. Experimental results are reported in the paper showing the effectiveness of the approach for a widely-known microcontroller core.

The ever increasing usage of microprocessor devices is sustained by a high volume production that in turn requires a high production yield, backed by a controlled process. Fault diagnosis is an integral part of the industrial effort towards these goals. This paper presents a novel cost-effective approach to the construction of diagnostic software-based test sets for microprocessors. The methodology exploits an existing post-production test set, designed for software-based self-test, and an already developed infrastructure IP to perform the diagnosis. An initial diagnostic test set is built, and then iteratively refined resorting to an evolutionary method. Experimental results are reported in the paper showing the feasibility and effectiveness of the approach for an Intel i8051 processor core

Embedded memory modules are sensitive components that deeply influence production yield of integrated devices. For fast yield improvement, an efficient manufacturing test must supply advanced defect characterization that helps in discovering technology weaknesses and finding strategies for improvement. This paper presents an industrial workflow for embedded memory diagnosis. It is based on the integration of March-based diagnostic BIST hardware in an IEEE 1500-compliant environment, and on a novel diagnostic algorithm for determining the fault model associated to the retrieved syndromes. An experimental implementation showing the feasibility of the approach is presented

Modern systems-on-chip (SoCs) allow integrating many different functional cores in the same piece of silicon. Their test requires taking fast decisions in the selection of structures and strategies at different stages of the design flow: early computation of area overhead, power consumption and test application time are indispensable in order to develop effective and efficient test for the overall chip, while taking into account physical constraints imposed by the available test equipment. Furthermore, once the test strategy has been selected and patterns generated for each module, additional nonnegligible effort is required to integrate the test program in an ATE-readable format. In this paper, we tackle these problems by means of a new software platform, leveraging descriptions of both the core-level test structure and the system-level requirements. Experimental results related to a realistic case of study underline the effectiveness of the tool and its potentialities in the IEEE 1500 environments

Determining the relation between defects and faults (fault diagnosis) in digital circuits is a key concept for semiconductors production yield improvement. Nowadays, fault diagnosis requires heavy computations and large data structures. This paper proposes a novel technique for reducing fault dictionary size for combinational and scanned circuits by means of pattern-ordering. The proposed algorithm manipulates conventional tree-based fault dictionaries. In such structures, faults are diagnosed by traversing the tree from its root to a leaf; we aim at globally reducing the length of such paths by a modified patterns order, thus also reducing the dictionary size. This approach does not cause any loss of information, since it is demonstrated for combinational circuits that the ability of a pattern set in diagnosing faults remains unaltered when modifying the patterns order. The effectiveness of the proposed approach is demonstrated for a set of sequential benchmarks equipped with scan chains.

Hardening SoCs against transient faults requires new techniques able to combine high fault detection capabilities with the usual requirements of SoC design flow, e.g., reduced design-time, low area overhead, and reduced (or null) accessibility to source core descriptions. This paper proposes a new hybrid approach which combines hardening software transformations with the introduction of an Infrastructure IP with reduced memory and performance overheads. The proposed approach targets faults affecting the memory elements storing both the code and the data, independently of their location (inside or outside the processor). Extensive experimental results, including comparisons with previous approaches, are reported, which allow practically evaluating the characteristics of the method in terms of fault detection capabilities and area, memory, and performance overheads.

In sub-micron technology circuits high integration levels coupled with the increased sensitivity to soft errors even at ground level make the task of guaranteeing systems' dependability more difficult than ever. In this paper we present a new approach to detect control-flow errors by exploiting a low-cost infrastructure intellectual property (I-IP) core that works in cooperation with software-based techniques. The proposed approach is particularly suited when the system to be hardened is implemented as a system-on-chip (SoC), since the I-IP can be added easily and it is independent on the application. Experimental results are reported showing the effectiveness of the proposed approach.

Discriminating between good and faulty chips is often not enough during IC manufacturing phases, where a complete understanding about failure mechanisms is required to ramp up production yield. When considering embedded memories, information about the whole set of faults needs to be extracted from the IC and processed: this asks for solutions supporting high data volume transfer. We propose an embedded architecture allowing efficient diagnosis of SoCs containing several BISTed memory cores, which minimizes ATE memory requirements for pattern storage and drastically speeds up the complete diagnostic procedure. Experimental results highlight the convenience of the approach with respect to alternative ATE driven procedures, while resorting to negligible area overhead.

Today's complex system-on-chip integrated circuits include a wide variety of functional IPs whose correct manufacturing must be guaranteed by IC producers. Infrastructure IPs are increasingly often inserted to achieve this purpose; such blocks, explicitly designed for test, are coupled with functional IPs both to obtain yield improvement during the manufacturing process and to perform volume production test. In some fields (e.g., the automotive one) there is a strong need for flexible and reusable test architectures able to guarantee effective and low-cost solutions for mission-mode fault detection capabilities within complex SoCs. In this paper, we propose to reuse structures inserted to support the manufacturing test to perform non-concurrent on-line test of SoCs. The feasibility of this approach and its costs have been evaluated on a real case of study including processor, memory and user defined logic cores.

This paper analyses the effects of single event upsets in an SRAM-based FPGA, with special emphasis for the transient faults affecting the configuration memory. Two approaches are combined: from one side, by exploiting the available information and tools dealing with the device configuration memory, we were able to make hypothesis on the meaning of every bit in the configuration memory. From the other side, radiation testing was exploited to validate the hypothesis and to gather experimental evidence about the correctness of the obtained results. As a major result, we can provide detailed information about the effects of SEUs affecting the configuration memory of a commercial FPGA device. As a second contribution, we describe a method for obtaining the same result with similar devices. Finally, the obtained results are crucial to allow the possible usage of SRAM-based FPGAs in safety-critical environments, e.g., by working on the place and route strategies of the supporting tools.

In this paper we describe how we applied a BIST-based approach to the test of a logic core to be included in system-on-a-chip (SoC) environments. The approach advantages are the ability to protect the core IP, the simple test interface (thanks also to the adoption of the P1500 standard), the possibility to run the test at-speed, the reduced test time, and the good diagnostic capabilities. The paper reports figures of the achieved fault coverage, the required area overhead, and the performance slowdown, and compares the figures with those for alternative approaches, such as those based on full scan and sequential ATPG.

This paper addresses the issue of diagnosing a memory core embedded in a complex SOC. The proposed solution is based on a P1500-compliant wrapper. The proposed solution exploits a hardware-implemented compression method that minimizes the amount of data to be transferred from the core to the ATE. The proposed solution takes into account several constraints existing in an industrial environment, such as reducing the time and area overheads required for diagnosis, and minimizing the cost of the external ATE. Experimental results are provided allowing evaluating the benefits and limitations of the adopted solution.

Commercial-off-the-shelf SRAM-based FPGA devices are becoming of interests for applications where high dependability and low cost are mandatory constraints. This paper proposes a new method for assessing the effects of SEUs in the device configuration memory. The method combines radiation testing for technology characterization and simulation-based fault injection for SEU propagation. Experimental results we gathered with the purpose of modeling the effects of SEUs in the FPGA configuration memory are reported and commented.

This paper addresses the issue of testing and diagnosing a memory core embedded in a complex SOC. The proposed solution is based on a P1500-compliant wrapper that follows a programmable BIST approach and is able to support both testing and diagnosis. Experimental results are provided allowing to evaluate the benefits and limitations of the adopted solution and to compare it with previously proposed ones. The solution takes into account several constraints existing in an industrial environment, such as minimizing the cost of test development, easing the reuse of the available architectures for test and diagnosis of different memory types and minimizing the cost of the external ATE.