BULK MICROMACHINING CHARACTERIZATION OF 0.2 MU-M HEMT MMIC TECHNOLOGYFOR GAAS MEMS DESIGN

Front-side bulk micromachining based on 0.2 mu m GaAs HEMT MMIC techno logy is presented. Several chemical solutions have been used to perfor m the etching procedure characterization in respect to the obtained ve rtical profiles. It has been verified that citric acid solution is the most appropriate selective etchant to build suspended GaAs/AlGaAs mes a-shaped structures, while both H3PO4 and NH4OH based anisotropic syst ems seem to be the most suitable for the free-standing triangular pris m-shaped structures. Moreover, all these three solutions could be appl ied to suspend only metal and intermetallic materials. Etch rates as w ell as cross-section profiles were obtained. Furthermore, the compatib ility of the etching procedure with the integrated electronics and the pad metallization has been successfully tested. The features and appl ications linked to the obtained structures are also discussed. (C) 199 8 Elsevier Science S.A. All rights reserved.