Depth and profile control in plasma etched MEMS structures

We have achieved uniform etched depth regardless of feature size by employi ng a combination of anisotropic plasma etching in inductively coupled plasm a (ICP) followed by wet etching. In our approach, the original feature is d ivided into small elementary features in a mosaic-like pattern. These indiv idual small features are all the same size and thus exhibit identical etch rates and sidewall profiles. Final patterns are completed by wet etching: t he ridges between the elementary features are removed in TMAH. In this pape r, we present the results obtained using this dry/wet etching sequence. The benefits and limitations of this method are described. Extensions to more complex multidepth structures are discussed. (C) 2000 Elsevier Science S.A. All rights reserved.