Resist profile characteristics caused by photoelectron and Auger electron blur at the resist-tungsten substrate interface in 100 nm proximity x-ray lithography

The replicated resist pattern characteristics caused by photoelectrons and Auger electrons generated from the W substrate were investigated for 100 nm proximity x-ray lithography. In addition, simulations for a hard x-ray spe ctrum having 2.36 keV average energy were performed to investigate the subs trate electron effects in hard x-ray lithography. In the experiments, it wa s found that the secondary electrons from the W substrate caused undercut a nd footing of resist profiles at the resist-substrate interface. Several bu ffer layers with varying thicknesses were tested to reduce the photoelectro n effects from the W substrate. The best thickness of the buffer layers for a good resist pattern profile was discovered to be >30 nm. Furthermore, th e experimental results were quantitatively compared to the results from com puter simulations using the Monte Carlo method. For hard x rays, we predict that the exposure latitude is worse on both W and Si substrates. (C) 2000 American Vacuum Society. [S0734-211X(00)13006-9].