DRY DEVELOPMENT FOR 0.25 MU-M TOP SURFACE IMAGING

The dry development of 0.25 mu m diffusion-enhanced silylated resist s tructures produced in a LAM Research Corporation TCP(TM)400((TM)) indu ctively coupled plasma etcher is studied. The processes consist of a l ow-selectivity, C2F6- containing, descum step followed by an oxygen-ba sed main and overetch step. An extensive study, based on statistically designed experiments, shows the effect of different process parameter s on anisotropy, selectivity, and the etch rates of silylated and unsi lylated resist that occur when using different dry development chemist ries. Solutions that independently control and enhance the selectivity and the anisotropy, while maintaining Vertical profiles and acceptabl e etch rates, are demonstrated. Optimal processes for the different ch emistries are compared. The effect that the different chemistries exer t on the lithographic performance is quantified, and the strong reduct ion of the proximity effect, both in terms of linewidth and profiles, resulting from SO2 addition is studied. It has been demonstrated that the results also apply to sub-0.25 mu m geometries and that none of th e tested chemistries interfere with subsequent etching of the polysili con substrate.