Wafer sort yield improvement by localizing and applying optical proximity correction on a metal bridging issue

This paper presents a wafer sort yield improvement on a device through changes in the optical proximity correction (OPC) algorithm. Failure analysis of the device showed metal bridging in a specific metal feature which caused gross functional failures in scan tests. Localizing the metal bridging was done by liquid crystal thermal analysis (LCTA) and device layout comparison. Sub-minimum spaces between metal lines were discovered in this metal layer that was created by an interaction between the existing OPC algorithm and a specific feature of two adjacent traces. Simple Boolean algorithms are added to the existing algorithm to correct the metal bridging to remove this final spacing issue and any others like it. This study reports a wafer sort yield improvement of 30% due to the OPC fix.