What is the best way to optimize integrated circuit layout for yield?

1 Understand the sources of defects

The first step to optimize your layout for yield is to understand the sources of defects that can affect your ICs. Defects are any irregularities or errors that occur during the fabrication process, such as dust particles, impurities, misalignment, overetching, or underetching. Defects can cause short circuits, open circuits, or performance degradation in your ICs. Some defects are random, meaning they can occur anywhere on the wafer, while others are systematic, meaning they are related to the design or the process parameters. You can use defect analysis tools and methods to identify and classify the defects in your ICs and estimate their impact on your yield.

2 Apply design rules and constraints

The second step to optimize your layout for yield is to apply design rules and constraints that can reduce the probability and severity of defects. Design rules are guidelines that specify the minimum dimensions, spacing, and alignment of the features in your layout, such as transistors, wires, and contacts. Design rules are based on the capabilities and limitations of the fabrication process and the equipment. By following the design rules, you can ensure that your layout is manufacturable and compatible with the process. Design constraints are additional requirements that can improve the quality and reliability of your layout, such as symmetry, redundancy, or shielding. Design constraints can help you avoid or mitigate some of the systematic defects that can affect your layout.

4 Implement design for manufacturability strategies

The fourth step to optimize your layout for yield is to implement design for manufacturability (DFM) strategies that can address some of the challenges and trade-offs of the fabrication process. DFM strategies are approaches that can bridge the gap between the design and the process by considering the physical and chemical phenomena that occur during the fabrication process and their effects on the layout. Some of the common DFM strategies are lithography-aware design, process variation-aware design, defect-aware design, and yield-aware design. DFM strategies can help you optimize your layout for yield by enhancing the printability, predictability, resilience, and profitability of your layout.

6 Evaluate and improve your yield

The final step to optimize your layout for yield is to evaluate and improve your yield by using various metrics, models, and methods. Yield evaluation is the process of measuring and analyzing your yield by using statistical methods, such as yield estimation, yield prediction, yield characterization, and yield diagnosis. Yield evaluation can help you understand the factors that influence your yield and identify the areas of improvement. Yield improvement is the process of applying corrective actions or preventive measures to increase your yield by using engineering methods, such as yield enhancement, yield optimization, yield learning, and yield management. Yield improvement can help you solve the problems that affect your yield and achieve your yield goals.