The silylation processes for positive and negative deep ultraviolet resists

In this report the experimental results of the resist silylation and O2‐plasma development are presented. The Soviet commercial novolac based photoresists of both positive and negative type and gas phase silylation in hexamethyldisilazane (HMDS) were used. The flood exposure of the resist films was made by Hg lamp or KrF laser. It is found that the silylated resist film mass growth (per resist surface square) must exceed 15×10−6 g/cm2 to provide the formation of the etching barrier layer under O2‐plasma development. The silylation kinetic is shown to be linear at first period. The dependence of the initial silylation rate on the experimental conditions was studied and results are discussed. Under the silylation of the highly crosslinked resist films the induction effect was observed. For both positive and negative processes the silylation conditions providing selective O2‐plasma development are determined. To enhance the contrast of O2‐plasma development the three‐stage procedure was elaborated.