A new, robust method for double sided processing bulk micromachined components made of an SOI (silicon on insulator) material is presented. Transfer of the SOI film to a second wafer using a bonding step enables double sided processing on 'flat' surfaces of the device film of the SOI wafer, thus avoiding lithography in deep cavities, high temperatures and high voltage processing steps. Room temperature oxygen plasma assisted wafer bonding was used to transfer the SOI film. This bonding step is expected to be CMOS compatible, which, makes it possible to integrate standard process electronics with micromachined devices on the wafer level. Before the bonding step the processing of the SOI and of the second wafer put no requirements on common compatibility, i.e. CMOS compatibility. In addition to double sided lithography and room temperature oxygen plasma assisted wafer bonding, the fabrication process makes use of the CMOS compatible anisotropic TMAH (tetramethyl ammonium hydroxide) etch and etch back technique. Fabrication of bulk micromachined accelerometer structures has shown that the process is successful.

Date Published: 19 April 2002
PDF: 12 pages
Proc. SPIE 4755, Design, Test, Integration, and Packaging of MEMS/MOEMS 2002, (19 April 2002); doi: 10.1117/12.462867

Published in SPIE Proceedings Vol. 4755:
Design, Test, Integration, and Packaging of MEMS/MOEMS 2002
Bernard Courtois; Jean Michel Karam; Karen W. Markus; Bernd Michel; Tamal Mukherjee; James A. Walker, Editor(s)