Resist heating with different writing strategies for high-throughput maskmaking

Distortion of critical dimension (CD) in electron beam (e-beam) lithography due to resist heating has become a major error factor in high-throughput m askmaking. Resist heating was examined using 50 kV raster and vector writin g strategies for a single pass and for four passes. All writing and process ing conditions (e-beam column, flash size, resist, development, writing thr oughput, etc.) were equal except for beam deflection. A 13.8% effective dos e change due to resist heating was found in the worst raster exposure condi tions, while in vector exposure, this value was greater than 130%. In four- pass printing, dose change was less than 1% for raster writing and 16.8% Fo r vector writing. Simulations of temperature rise were done using TEMPTATIO N (temperature simulation) software. The temperature rise was found to be 3 8 degrees C for raster exposure but greater than 220 degrees C with vector exposure for the writing conditions used. SPR 700 and EER 900 novolac resis ts showed similar behavior with regard to heating.