Characterization of a-Si:H resists for a vacuum-compatible photolithography process

We report the characterization of amorphous hydrogenated silicon (a-Si:H) films for use as a dry photoresist, in a vacuum-compatible photolithography process. a-Si:H films are deposited, patterned via excimer laser exposure, and developed in a hydrogen plasma. Experiments on the effects of exposure environment and laser pulse energy density were carried out to determine the optimum conditions for the technique. Transmission electron microscopy (TEM) shows the excimer-exposed a-Si:H surfaces to be polycrystalline in nature. The polycrystalline surfaces serve very well as an etching mask during plasma development, exhibiting etch selectivities over 600:1. Preliminary methods for reducing undesirable surface roughness at the exposed surfaces are also discussed. © 2004 American Vacuum Society.