Efficient standard cell abutment checker

An efficient and exhaustive standard-cell abutment verification tool is developed to ensure 100% layout verification coverage of design rule check (DRC) on boundaries created by standard-cell abutment during placement, Vt swap and ECO (engineering change orders). Several case-reduction techniques are presented to remove the redundancy of duplicate abutment. This methodology can achieve one order-of-magnitude reductions in the test area to exercise all boundaries created by all placement permutations in standard cell libraries.