Impact of the OMOG Substrate on 32 nm Mask OPC Inspectability,Defect Sensitivity and Mask Design Rule Restrictions

摘要

Aggressive optical proximity correction (OPC) has enabled the extension of advanced lithographic technologies to the32nm node. The associated sub-resolution features, feature-feature spacings, and fragmented edges in the design data aredifficult to reproduce on masks and even more difficult to inspect. The patterns themselves must be differentiated fromdefects for inspectability, while the ability to recognize small deviations must be maintained for sensitivity. This must bedone without restricting necessary OPC design features. The semi-transparent nature of industry-standard 6% attenuatedphase shift substrates introduces a host of problems relative to inspectable dimensions and subsequent defectsensitivities. The result is a reduction in inspectability, defect sensitivity and the inability to inspect smaller criticaldimensions and OPCed features. The introduction of a binary-type attenuated phase shift film improves the ability toinspect smaller critical dimensions and smaller OPC features without loss of inspectability and sensitivity extending thecapability of existing inspection hardware for 32nm ground rule masks. This paper introduces inspection characterizationresults for this new film, opaque MoSi on glass (referred to as OMOG in this paper) and draws a correlation between thefilm's transmission qualities and inspectability of 32nm OPC features. The paper will further show a correlation betweenOPC feature size and defect sensitivity for 32nm ground rule designs. Aerial Image (AIMS) analysis will be used toidentify areas where the enhanced inspection capability can be leveraged to avoid unnecessary restrictions on OPC.