Abstract
We have been targeting “Silicon anisotropic wet etching in alkaline solution”, which is one of the key processing technologies for silicon MEMS. In the future, it is necessary to develop environment-friendly wet etching process. However, the etching with a low-concentration alkaline solution is difficult because the etched surface became rough when a low-concentration （about 20 wt% or less） alkaline aqueous solution is used. In this study, the wet etching method using droplets of 5 wt%KOH solution was investigated. The droplet is heated locally and the moisture in the droplet evaporates just before etching, then the droplet turns to high-concentration. As a result, it was found that a smooth etching surface, which cannot be generally obtained with a 5 wt% KOH aqueous solution, can be obtained under appropriate conditions of the amount of droplets and the heating temperature. This etching method has the advantage of localized etching, and it can be applied not only to single crystal silicon etching but also to etching of new materials for micro devices.
