Mask membrane distortions due to pattern transfer for electron-beam lithography (SCALPEL) masks

In order to successfully employ Scattering with angular Limitation Projecti on Electron-Beam Lithography (SCALPEL) to produce integrated circuits with features below 0.13 mu m, mask membrane distortions (which lead to pattern placement errors) must not exceed the error budget. When designing a mask, finite element (FE) models are created to identify sources of distortion an d quantify the resulting errors. Distortions arise during fabrication, moun ting, and in situ exposure of the mask. The focus of this study was to dete rmine the mask membrane distortions induced during the pattern transfer pro cess for a large format SCALPEL mask. Three cases were investigated: the IB M Talon pattern, 100% removal of the scatterer layer, and 50% removal of th e scatterer layer. The IBM Talon pattern was chosen to quantify typical pat tern specific-distortions while the other two cases, 100% and 50% removal o f the scatterer layer, were investigated to determine distortions correspon ding to worst case situations.