A novel bilevel resist system

Abstract

A bilevel system, consisting of PMMA and RD2000N (Hitachi) is described which has no discernable interaction between the resists and no processing interaction. The thin RD2000N resolution layer has very high absorption below 2900 Å and forms a high contrast mask for optical pattern transfer to the thick base PMMA layer. High fidelity step coverage of wet and dry etched oxides 7200 Å high is demonstrated with good linewidth control. The bilevel is capable of resolving 0.75 μm features over steps with good acuity. Preliminary results indicate that linewidth control with the bilevel process is comparable to a single level RD2000N process and has a lσ value of ∼.09 μm nearly independent of linewidth. The RD2000N layer shows a greater sensitivity to process variation than the PMMA. A parametric evaluation shows a dependence of linewidth on development time of 0.02 μm/s and a dependence of 0.11 μm/s for a 17 s exposure time. The resist system has enough dry etch resistance to use plasma etch pattern transfer as a complement to optical pattern transfer.

An Aqueous Developable Deep UV/Electron Beam Negative Resist

“…PMMA can also be plasma developed under selective anisotropic etching conditions. A similar process has been published recently (18). In this work some plasma etch rate data of PMMA in a bilevel system was reported.…”

A molded deep‐UV portable conformable masking system

“…Several authors have addressed the capped system (9)(10)(11)(12)(13). There are certain desired improvements for such systems.…”