Stencil mask defect inspection system and advanced application

Abstract

A new inspection system for stencil mask using transmission electron beam (B-beam) has been developed to detect defects on masks for Electron Projection Lithography (EPL) and Low Energy E-beam Proximity projection Lithography (LEEPL) for 65 nm design rule and beyond [1]• For high-performance image acquisition, the combination of multi-line Time Delay integration (TDI) -CCD camera and electron optic system (EOS) have been achieved very wide field-of-view and accurate imaging in this system.In Image Processing Unit, "Multi Algorithm Processing" is used for defect detection. One of "Multi Algorithm Processing" focuses on defects at corners of patterns. This is a new and very flexible algorithm to detect corner defects. It realizes very high detection performance compared with conventional Die-To-Database inspection. The minimum detectable defect size is smaller than 1 pixel. The pixel size is 50 nm for EPL mask and 30 nm for LEEPL mask. The performance of the system also has been confirmed using resist pattern wafer inspection results after EPL and LEEPL printing.