Design-aware mask inspection

Abstract

Mask inspection has become a major bottleneck in the manufacturing flow taking up as much as 30% of the total manufacturing time. In this work we explore techniques to improve the reticle inspection flow by increasing its design awareness. We develop an algorithm to locate non-functional features in a post-OPC layout with 100% accuracy without using any design information. Using this, and timing information of the design (if available), we assign a minimum size defect to each reticle feature that could cause the design to fail. The criticality of various reticle features is then used to partition the reticle such that each partition is inspected at a different pixel size and sensitivity so that the false+nuisance defect count is reduced without missing any critical defect. Up to 4X improvement in false+nuisance defect count is observed with our technique resulting in up to 55% improvement in first pass yield coming from reduction in nuisance defects and substantial reduction in defect review load.