Pattern Transfer of 3-dimensional Fine Structures to the Si Substrate with expanding the Vertical Dimensions Using the Reactive Ion Etching

点击翻译按钮获取中文摘要

In this research, we aimed at developing a pattern transfer technique of 3-dimensional structures from a resist mask to a Si substrate with expanding their vertical dimensions. This key technique will be useful for fabricating a microlens and a micromachine etc. which need deeper vertical dimension than the resist thickness. Multi-level step structures were formed to a resist layer using the electron beam lithography with raster beam scan and multiplying exposures of different mask patterns. The pattern transfer was performed using the reactive ion etching utilizing the etching selectivity between the resist mask and the substrate.It is demonstrated that resist cross sections of multi-level steps can be transferred to Si substrates with expanding their vertical dimensions about 5 times by the RIE using SF_6 gas, while the cross sectional shapes were deformed by the pattern transfer. The isotropic nature of RIE degraded the quality of transferred patterns when their step widths were as fine as 1μm. These problems were improved by RIE with mixing CHF_3 (90%) gas to SF_6 (10%), whereas the degree of expanding the vertical dimension was decreased. It is also presented that the degree of expanded pattern transfer is controllable by changing the RF bias voltage at RIE process.