Method for analyzing placement context sensitivity of standard cells
A disclosed method for evaluating placement context sensitivity in the design of an integrated circuit includes accessing a standard cell library comprising a database of standard cells and determining generating boundary data for each of the standard cells. The boundary data for a standard cell indicates the layout of features located within boundary regions of the standard cell. The method includes merging or consolidating boundary data for any two standard cells if their boundary data is the same to determine a canonical or minimal set of boundary regions. The disclosed method further includes enumerating and evaluating all combinations of pairs of the canonical boundary regions and, responsive to identifying of a proximity-based sensitivity or exception, modifying, notating, or otherwise remediating the applicable one or more standard cells that correspond to the boundary region combination that raised the exception.
1. An integrated circuit design method, comprising:
accessing a standard cell library including a plurality of standard cells, wherein a standard cell comprises a data structure indicative of a layout of a plurality of physical elements defining the standard cell;
determining, from the standard cell library, a first boundary library including a first boundary structure corresponding to each of the plurality of standard cells, wherein the first boundary structure indicates a layout of a first boundary region of the corresponding standard cell;
responsive to identifying multiple first boundary structures in the first boundary library sharing a common layout, merging, by a data processing system, the multiple first boundary structures into a common boundary structure to produce a reduced first boundary library;
checking, by the data processing system, local placement context for the standard cell library by checking local placement context for boundary structure pairs comprising a first boundary structure from the reduced first boundary library and a second boundary structure from a second boundary library corresponding to a second boundary region of the standard cells; and
responsive to an exception raised by the local placement context checking of a first boundary structure pair:
identifying standard cell pairs, including a first standard cell and a second standard cell, that include the first boundary structure pair; and
resolving, by the data processing system, the exception by performing an operation selected from:
annotating the standard cell pairs that have the first boundary structure pair to constrain a subsequent standard cell placement resulting in a standard cell pair possessing the first boundary structure pair; and
remediating the first boundary structure pair, wherein the remediating includes:
generating a remediated first boundary structure pair including a remediated first boundary structure; and
replacing instances of the first boundary structure in the first standard cell of standard cell pairs possessing the first boundary structure with the remediated first boundary structure.
2. The method of claim 1 , wherein identifying the standard cell pairs includes, tracing the exception back to standard cells whose first boundary structures were merged into the common boundary structure.
3. The method of claim 1 , wherein a layout of the remediated first boundary structure differs from a layout of the first boundary structure.
4. The method of claim 3 , wherein a function of the remediated first boundary structure matches a function of the first boundary structure.
5. The method of claim 1 , further comprising:
determining a number of edge regions upon which to perform the checking of local placement context; and
determining a size of each of the edge regions.
6. The method of claim 1 , further comprising:
determining, from the standard cell library, a second boundary library corresponding to the second boundary region of each of the standard cells; and
responsive to identifying matching second boundary structures in the second boundary library, merging the matching second boundary structures into a common second boundary structure to produce a reduced second boundary library.
7. The method of claim 1 , wherein the first boundary region corresponds to a portion of the standard cell located within a predetermined distance of a right standard cell boundary and the second boundary region corresponds to a portion of the standard cell located within the predetermined distance of a left standard cell boundary.
8. The method of claim 7 , wherein the constraining prevents placement of standard cells possessing the first boundary structure adjacent and to the left of standard cells possessing the second boundary structure.
9. The method of claim 1 , wherein the first boundary region corresponds to a portion of the standard cell located within a predetermined distance of a top standard cell boundary and the second boundary region corresponds to a portion of the standard cell located within the predetermined distance of a bottom standard cell boundary.
10. The method of claim 9 , wherein the predetermined distance is based on an optical radius of an imaging system associated within the standard cell library.
11. A non-transitory computer readable medium including processor-executable program instructions comprising instructions for:
determining a first canonical set of boundary region structures associated with a first boundary region of standard cells in a standard cell library;
determining a second canonical set of boundary region structures associated with a second boundary region of the standard cells, wherein the first boundary region and second boundary region comprise adjoining regions of adjacently located standards cells;
performing proximity analysis on boundary region combinations comprising a boundary region structure from the first canonical set and a boundary region structure from the second canonical set;
responsive to the proximity analysis raising an exception for a specific boundary region combination, identifying standard cell pairs associated with the specific boundary region combination; and
remediating the standard cell pairs to prevent any standard cell pair from raising the exception.
12. The computer readable medium of claim 11 , wherein remediating the standard cell pairs includes modifying a layout of the first boundary region of a first standard cell in the standard cell pair.
13. The computer readable medium of claim 11 , wherein remediating the standard cell pairs includes annotating a first standard cell in a first standard cell pair with a placement constraint preventing placement of the first standard cell with its first boundary region adjacent to the second boundary region of the second standard cell.
14. The computer readable medium of claim 11 , wherein determining the first canonical set of boundary regions includes:
merging all first boundary region structures sharing a first layout in common into a first common boundary region structure.
15. The computer readable medium of claim 11 , wherein the proximity analysis includes analyzing boundary region combinations for photolithography hotspots, lithography induced timing variability, and colorability for double-patterning photolithography.
16. A data processing system, comprising:
a processor; and
a storage medium including processor-executable program instructions for evaluating placement context sensitivity, the program instructions, when executed by the processor, causing the processor to perform operations comprising:
determining, from a standard cell library including a plurality of standard cells, each indicative of a layout of a plurality of standard cell physical elements, a first boundary library including a first boundary structure corresponding to each of the plurality of standard cells, wherein the first boundary structure indicates a layout of a first boundary region of the corresponding standard cell;
responsive to identifying multiple first boundary structures in the first boundary library sharing a common layout, merging the multiple first boundary structures into a common boundary structure to produce a reduced first boundary library;
checking local placement context for the standard cell library by checking local placement context for boundary structure pairs comprising a first boundary structure from the reduced first boundary library and a second boundary structure from a second boundary library corresponding to a second boundary region of the standard cells; and
responsive to an exception raised by the checking of local placement context of a first boundary structure pair:
identifying standard cell pairs, including a first standard cell and a second standard cell, that have the first boundary structure pair; and
resolving the exception by performing an operation selected from:
annotating the standard cell pairs that have the first boundary structure pair to constrain a subsequent standard cell placement resulting in a standard cell pair possessing the first boundary structure pair; and
remediating the first boundary structure pair, wherein the remediating includes:
generating a remediated first boundary structure pair including a remediated first boundary structure; and
replacing instances of the first boundary structure in the first standard cell of standard cell pairs possessing the first boundary structure with the remediated first boundary structure.
17. The system of claim 16 , wherein a layout of the remediated first boundary structure differs from a layout of the first boundary structure and wherein a function of the remediated first boundary structure matches a function of the first boundary structure.
18. The system of claim 16 , wherein the operations include:
determining a number of edge regions upon which to perform the checking of local placement context; and
determining, a size of each of the edge regions.
19. The system of claim 16 , wherein the operations include:
determining, from the standard cell library, a second boundary library corresponding to the second boundary region of each of the standard cells; and
responsive to identifying matching second boundary structures in the second boundary library, merging the matching second boundary structures into a common second boundary structure to produce a reduced second boundary library;
wherein the placement constraints prevent placement of the standard cells identified adjacent to one another as in the specific boundary region combination.
20. The system of claim 16 , wherein performing proximity analysis includes analyzing boundary region combinations for photolithography hotspots, photolithography induced timing variability, and colorability for double-patterning photolithography.