Comparison of liquid- And vapor-phase silylation processes for 193-nm positive-tone lithography

Liquid- and vapor-phase silylation processes are compared for a 193-nm positive-tone lithographic process using polyvinyiphenol as a resist. The liquid-phase process, using a mixture of xylene, hexamethylcyclotrisilazane, and propylene glycol methyl ether acetate, was found to have higher silylation contrast, better sensitivity, and a smaller proximity effect (a decrease in silylation depth for smaller feature sizes). These factors result in a larger exposure latitude, particularly at feature sizes below 0.5 .tm. These advantages are greatly offset, however, by the increased chemical costs, which are estimated to be more than 100 times greater than for the vapor-phase process.