Although many physical limitations have been reached in modern micro-lithography, printed critical dimensions continue to shrink according to the International Technology Roadmap for Semiconductors (ITRS) [1]. To meet the demands imposed by this guideline, the traditional separation between design and manufacturing communities is being bridged. Many EDA tools package manufacturing data for delivery into established simulation engines for design verification. However, none of them provide practical implementations of design optimizations at an early stage in the design flow.This paper presents an automated layout modification flow for metal layers with the goal of enhancing manufacturability. It can easily be deployed in a current custom design flow in a way that is visible to designers. The result of this scheme is improvements to process windows and yield, while minimizing circuit performance detractors. The flow is verified through analyses of both the impact on circuit performance and the benefit to manufacturability. It has been implemented in a state-of-the-art 65 nm chip design. Both silicon yield and electrical performance data are currently being collected and analyzed.

While performance specifications are verified before sign-off for a modern nanometer scale design, extensive application of optical proximity correction substantially alters the layout introducing systematic variations to the simulated and verified performance. As a result, actual on-silicon chip performance is quite different from sign-off expectations. This paper presents a new methodology to provide better estimates of on-silicon performance. The technique relies on the extraction of residual OPC errors from placed and routed full chip layouts to derive actual (i.e., calibrated to silicon) CD values that are then used in timing analysis and speed path characterization. This approach is applied to a state-of-the-art microprocessor and contrasted with traditional design flow practices where ideal (i.e., drawn) Lgate values are employed, leading to a subsequent lack of predictive power. We present a platform for diagnosing and improving OPC quality on gates with specific functionality such as critical gates or matching transistors. Furthermore, with more accurate timing analysis we highlight the necessity of a post-OPC verification embedded design flow, by showing substantial differences in the Si-based timing simulations in terms of significant reordering of speed path criticality and a 36.4% increase in worst-case slack. Extensions of this methodology to multi-layer extraction and timing characterization are also proposed.

Resolution enhancement techniques (RET) such as optical proximity correction (OPC) and phase-shift mask (PSM) technology are deployed in modern processes to increase the fidelity of printed features, especially critical dimensions (CD) in polysilicon. Even given these exotic technologies, there has been momentum towards less exibility in layout, in order to ensure printability. However, there has not been a systematic study of the performance and manufacturability impact of such a move towards restrictive design rules. In this paper we present a design ow that evaluates the application of various restricted design rule (RDR) sets in deep submicron ASIC designs in terms of circuit performance and parametric yield. Using such a framework, process and design engineers can identify potential solutions to maximize manufacturability by selectively applying RDRs while maintaining chip performance. In this work we focus attention on the device layer which is the most difficult design layer to manufacture. We quantify the performance, manufacturability and mask cost impact of several common design rules. For instance, we find that small increases in the minimum allowable poly line end extension beyond active provide high levels of immunity to lithographic defocus conditions. Also, modification of the minimum field poly to diffusion spacing can provide good manufacturability, while a single pitch single orientation design rule can reduce gate 3σ uncertainty. Both of these improve in data volume as well, with little to no performance penalties. Reductions in data volume and worst-case edge placement error are on the order of 20-30% and 30-50% respectively compared to a standard baseline design rule set.

As minimum feature sizes continue to shrink, patterned features have become significantly smaller than the wavelength of light used in optical lithography. As a result, the requirement for dimensional variation control, especially in critical dimension (CD) 3σ, has become more stringent. To meet these requirements, resolution enhancement techniques (RET) such as optical proximity correction (OPC) and phase shift mask (PSM) technology are applied. These approaches result in a substantial increase in mask costs and make the cost of ownership (COO) a key parameter in the comparison of lithography technologies. No concept of function is injected into the mask flow; that is, current OPC techniques are oblivious to the design intent, and the entire layout is corrected uniformly with the same effort. We propose a novel minimum cost of correction (MinCorr) methodology to determine the level of correction for each layout feature such that prescribed parametric yield is attained with minimum total RET cost. We highlight potential solutions to the MinCorr problem and give a simple mapping to traditional performance optimization. We conclude with experimental results showing that substantial RET costs may be saved while maintaining a given desired level of parametric yield.