<title>PSM defect repair using currently available tools</title>

Abstract

ABsTRAcT Phase shifting masks (PSMs) have proven to increase resolution in optical lithography'3. However, the production of defect free PSMs still remains a challenge. The increase in resolution not only decreases the maximumallowed chromium defect size, but also introduces phase defects which print at even smaller sizes than conventionaldefects. This paper will describe typical defects on quartz etched Rim shifting and Attenuated PSMs as well as the minimum requirements for repairing these defects during the process development phase. Finally, possible PSM repair methods using conventional mask repair techniques such as focused ion beam sputtering and laser ablation willbe discussed. 1. INTRODUcTION Phase shifting masks (PSMs) are an exciting new technology to be tamed for production use. Although invented more than 10 years ago, its complexity still seems insurmountable. The PSM manufacturing process resembles a wafer lithography process more than a conventional mask process. Thus, answers on how to inspect and repair masksthat use this new technology are necessary.Production-worthy PSM repair tools are forecasted to be available by the end of 1994. Each of these tools will