|
The physics of scaling manufacturing processes is driving the need to integrate the process of physical design with upstream design decisions. The primary physical effect from scaling is increased interconnect resistance, which causes increased delay and noise in final circuit behavior. Increasing wire aspect ratio to mitigate resistance adds increased coupling, which also increases delay and noise. Finally, the manufacturing challenges of lithography and variation control require significant attention, if not fundamental changes in the physical design process.
Because increasing physical effects are determined by the final stage of laying out a design, the current design methodology of iterating between upstream design changes and layout is growing increasingly futile. Today, it takes multiple clock cycles to cross a die because of interconnect resistance; the impact of scaling physics is a primary consideration in the very first architectural design decisions of today's designs.
Research in both tools and methodologies that more tightly integrate traditional design decisions with downstream physical design decisions are needed. In the Strategic CAD Labs, we have two primary investigation areas in physical design:
| 
