Thin resist process having high dry-etching resistance in 0.13-μm KrF lithography

The dependence of resists materials nd process conditions on dry etching resistance was examined for polysilicon, silicon oxide and metal etch applications. Thin resist process is a simple and cost-effective technique for resolution enhancement, and it enlarges the process margin because of reduction of the resist pattern aspect ratio and improved film transparency. However, to use thin resist process in manufacturing, sufficient etch selectivity is required for function of the etching mask. The high dry etching resistance resist process or the hard mask process was one of the solutions. In this study, we evaluated the dry etching rate of KrF resist materials such as a positive photoresist (acetal type and ESCAP type) and a negative photoresist, and the effect of process conditions such as baking temperature and electron beam (EB) exposure. Under polysilicon and metal etching conditions, the etch rate dependence or resist materials such as ESCAP and the negative resist indicated high dry etching resistance compared with the acetal-type resist. However, under silicon oxide etching conditions, etch rate dependence on the kind of resist polymer was small. These data indicated that the etch rate dependence on resist polymer is strongly governed by the etching conditions. High-temperature baking and EB curing processes were effective for improving etch selectivity. Regarding the influence of baking temperature, although etch rates were strongly dependent on etching conditions, the effect of etch rate change ratio by baking was not dependent on the etching conditions. The EB curing process is the effective in improving etching resistance, but it also shows dependence on the etching conditions. The EB curing process was quite effective in improving etching resistance, but it also shows dependence on the etching conditions. The EB curing process was quite effective in the case of polysilicon and metal etch processing. Therefore, the dry etching resistance for thin-layer application was improved by the resist process, although it strongly depended on the etch process conditions. Form the analysis of resists polymer and residual solvent by FR-IR, GC-MS and DSC, it seemed that the effect of etch resistance improvement by EB curing is mainly caused by the resin's structural change. On the other hand, the effect of baking conditions was mainly due to the solvent in the resist. Finally, we confirmed the lithographic and etching performance by using the EB curing process for three types of resists with 130nm node gate, contact and metal layers.