ION EXPOSURE CHARACTERIZATION OF A CHEMICALLY AMPLIFIED EPOXY RESIST

The negative-tone proton exposure characteristics of a chemically ampl ified resist based on an epoxy resin (Shell SU-8) and an onium salt se nsitizer (General Electric UVE-1014) are described. This resist was de veloped by IBM for UV, electrons, and x rays, for which it exhibits hi gh contrast, good etch resistance, low minimum dose for exposure, exce llent adhesion to a variety of substrates, and resolution of better th an 0.1 mum. In the present work, the exposure properties of this resis t were measured as a function of sensitizer concentration when exposed with 100 keV protons. The best contrast measured for 100 keV protons was 1.4, at a sensitizer concentration of 1 wt % and the corresponding minimum dose for exposure was 0.13 muC/cm2. Sub-0.1 mum resolution wa s also demonstrated using ion beam proximity printing. However, the re sist develops as a porous mat for low ion doses, a phenomenon which ca n result in significant pattern edge roughness. It is suggested that t his problem arises because the resist is sufficiently sensitive to reg ister single ion tracks.