MECHANICAL MODELING OF PROJECTION ELECTRON-BEAM LITHOGRAPHY MASKS

The production of microchips with circuit features in the sub-0.13 mu m regime will require an advanced lithography technique such as SCatte ring with Angular Limitation Projection Electron Lithography (SCALPEL) . The mask used in this technique is subject to intrinsic and extrinsi c loads during fabrication, mounting, and exposure, giving rise to mec hanical distortions which lead to pattern placement errors. In order t o develop a low distortion mask, finite element models have been creat ed to identify sources of distortion and quantify the resulting errors . The models are then used as predictive tools to optimize the design of the mask so that distortions do not exceed the error budget. The fo cus of this study was to investigate the mask membrane distortions ind uced during the fabrication process and pattern transfer for a prelimi nary test case of a SCALPEL mask. More specifically, out-of-plane and in-plane distortions were calculated and the sensitivity of this respo nse to variations in mask design parameters was determined.