Channel length scaling for footprint compatible digital library cell design
A library cell is designed, and then the width of the polys is increased, and the polys and contacts are shifted in order to maintain poly-to-poly and contact-to-poly spacing. The method can be used in association with a 45 nm digital library cell. Specifically, a library cell having 40 nm polys is designed, and then the width of each of the polys is increased by 5 nm to 45 nm, and the polys and contacts are shifted in order to maintain poly-to-poly and contact-to-poly spacing. The poly lines and contacts can be shifted by starting at the center and going out radially, or by beginning at the perimeter and moving radially inward. The method can be used with any library cell design which is entirely GDS based, including, for example, 32 nm library cell design.
1. A GDS-based method of channel length scaling in library cell design, said GDS-based method comprising: using a GDS-based tool to design a library cell having a plurality of polys (polysilicon) and a plurality of contacts, wherein each of the polys are spaced away from each other, and wherein each of the contacts and polys are spaced away from each other; using the GDS-based tool to modify the library cell by increasing the width of the polys and using the GDS-based tool to shift the polys and the contacts such that poly-to-poly spacing is maintained and contact-to-poly spacing is maintained, wherein the step of shifting the polys and the contacts comprises at least one of; starting at a center of the polys and going out radially; and starting at a perimeter of the polys and moving radially inward.
2. The method as recited in claim 1 , wherein the step of increasing the width of the polys comprises increasing the width by 5 nm.
3. The method as recited in claim 1 , wherein the step of increasing the width of the polys comprises increasing the width from 40 nm to 45 nm.
4. The method as recited in claim 1 , wherein the step of shifting the polys and the contacts such that poly-to-poly spacing is maintained comprises maintaining the spacing between the polys at minimum allowed space.
5. The method as recited in claim 1 , wherein the step of shifting the polys and the contacts such that contact-to-poly spacing is maintained comprises maintaining the spacing between the contacts and polys at minimum allowed space.
6. The method as recited in claim 1 , wherein the step of shifting the polys and the contacts such that poly-to-poly spacing is maintained comprises maintaining the spacing between the polys at minimum and maintaining the spacing between the contacts and polys at minimum.
7. The method as recited in claim 1 , wherein the step of designing a library cell comprises designing a library cell which comprises metal-1 patterns, and the method comprises maintaining, and not changing, the metal-1 patterns.
8. The method as recited in claim 1 , wherein the step of designing a library cell comprises designing a library cell which comprises an N-active and Proactive sources and drains, and the method further comprises changing areas of the N-active and the P-active sources and drains.
9. The method as recited in claim 1 , wherein the step of designing a library cell comprises designing a library cell which comprises metal-1 patterns, an N-active and P-active, and the method comprises maintaining, and not changing, the metal-1 patterns, and the method comprises changing the areas of the N-active and the P-active sources and drains.