Critical evaluation of photomask needs for competing 65-nm node RET options

摘要

A comprehensive set of numerical, mask pattern operators is developed and applied for the purpose of understanding photomask fabrication tolerances supporting aggressive, optical lithography resolution enhancement. Using these numerical operators, the content and fidelity of the photomask is systematically degraded and wafer level results predicted using experimentally calibrated simulation. The concept of a mask sensitivity matrix is introduced and used as a bridge to full Monte Carlo analysis of photomask fabrication errors. A statistical approach to analyze mask defect tolerances for resolution enhancement options is presented within the same numerical framework. Such methodical and detailed analysis of mask construction parameters is a vital step toward understanding the complex interaction between mask quality and printed image and hence the delivery of 65 nm node lithography capability.