Post-silicon validation is a crucial yet challenging problem primarily due to the increasing complexity of the semi-conductor value chain. Existing techniques cannot keep up with the rapid increase in the complexity of designs. Therefore, post-silicon validation is becoming an expensive bottleneck. Robust performance tuning is relevant to compensate impacts of process variations and non-ideal design implementations. We propose a novel approach based on Deep Reinforcement Learning and Learn to Optimize. The method automatically learns flexible tuning strategies tailored to specific circuits. Additionally, it addresses high-dimensional tuning tasks, including mixed data types and dependencies, e.g., on operating conditions. In this work, we introduce Learn to Tune and demonstrate its appealing properties in post-silicon validation, e.g., lower computational cost or faster time-to-optimize, allowing a more efficient adaption of the tuning to changing tuning conditions than classical methods.

Test methods that can keep up with the ongoing increase in complexity of semiconductor products and their underlying technologies are an essential prerequisite for maintaining quality and safety of our daily lives and for continued success of our economies and societies. There is a huge potential how test methods can benefit from recent breakthroughs in domains such as artificial intelligence, data analytics, virtual/augmented reality, and security. The Graduate School on “Intelligent Methods for Semiconductor Test and Reliability” (GS-IMTR) at the University of Stuttgart is a large-scale, radically interdisciplinary effort to address the scientific-technological challenges in this domain. It is funded by Advantest, one of the world leaders in automatic test equipment. In this paper, we describe the overall philosophy of the Graduate School and the specific scientific questions targeted by its ten projects.

With the dramatically increasing requirements on semiconductor products, improving the yield is one of the major tasks for semiconductor manufacturers. To minimize losses, automatic and efficient wafer testing tools are required to quickly notify the engineers of potential problems. One such technique is wafer map defect pattern classification, which has inspired and motivated extensive research over the last decades. Many popular studies often design novel wafer map defect identification algorithms based on manual feature extraction, statistical learning and deep neural networks, having achieved significant advancement and success. However, these methods often face challenges of training large-scale networks and few of them have noticed the full usage of the information within each wafer map. Based on the concerns above, this paper proposes a multi-task learning framework based on neural networks that fuses the information of the entire wafer map as well as the state of each individual die to enhance the defect pattern classification capability. Extensive experiments on a public real-world dataset have been conducted to justify the effectiveness of our method. Specifically, our method achieved an classification accuracy of 96.3%, which was better or comparable to other state-of-the-art approaches that required notably larger network sizes and heavy data augmentation.

In recent years, the usage of ensemble learning in applications has grown significantly due to increasing computational power allowing the training of large ensembles in reasonable time frames. Many applications, e.g., malware detection, face recognition, or financial decision-making, use a finite set of learning algorithms and do aggregate them in a way that a better predictive performance is obtained than any other of the individual learning algorithms. In the field of Post-Silicon Validation for semiconductor devices (PSV), data sets are typically provided that consist of various devices like, e.g., chips of different manufacturing lines. In PSV, the task is to approximate the underlying function of the data with multiple learning algorithms, each trained on a device-specific subset, instead of improving the performance of arbitrary classifiers on the entire data set. Furthermore, the expectation is that an unknown number of subsets describe functions showing very different characteristics. Corresponding ensemble members, which are called outliers, can heavily influence the approximation. Our method aims to find a suitable approximation that is robust to outliers and represents the best or worst case in a way that will apply to as many types as possible. A ‘softmax’ or ‘soft-min’ function is used in place of a maximum or minimum operator. A Neural Network (NN) is trained to learn this ‘soft-function’ in a two-stage process. First, we select a subset of ensemble members that is representative of the best or worst case. Second, we combine these members and define a weighting that uses the properties of the Local Outlier Factor (LOF) to increase the influence of non-outliers and to decrease outliers. The weighting ensures robustness to outliers and makes sure that approximations are suitable for most types.

Feature selection is generally used as one of the most important preprocessing techniques in machine learning, as it helps to reduce the dimensionality of data and assists researchers and practitioners in understanding data. Thereby, by utilizing feature selection, better performance and reduced computational consumption, memory complexity and even data amount can be expected. Although there exist approaches leveraging the power of deep neural networks to carry out feature selection, many of them often suffer from sensitive hyperparameters. This paper proposes a feature mask module (FM-module) for feature selection based on a novel batch-wise attenuation and feature mask normalization. The proposed method is almost free from hyperparameters and can be easily integrated into common neural networks as an embedded feature selection method. Experiments on popular image, text and speech datasets have shown that our approach is easy to use and has superior performance in comparison with other state-of-the-art deep-learning-based feature selection methods.