20 May 1996 Integrated mold/surface-micromachining process
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We detail a new monolithically integrated silicon mold/surface-micromachining process which makes possible the fabrication of stiff, high-aspect-ratio micromachined structures integrated with finely detailed, compliant structures. An important example, which we use here as our process demonstration vehicle, is that of an accelerometer with a large proof mass and compliant suspension. The proof mass is formed by etching a mold into the silicon substrate, lining the mold with oxide, filling it with mechanical polysilicon, and then planarizing back to the level of the substrate. The resulting molded structure is recessed into the substrate, forming a planar surface ideal for subsequent processing. We then add surface-micromachined springs and sense contacts. The principal advantage of this new monolithically integrated mold/surface-micromachining process is that it decouples the design of the different sections of the device: in the case of a sensitive accelerometer, it allows us to optimize independently the proof mass, which needs to be as large, stiff, and heavy as possible, and the suspension, which needs to be as delicate and compliant as possible. The fact that the high-aspect-ratio section of the device is embedded in the substrate enables the monolithic integration of high- aspect-ratio parts with surface-micromachined mechanical parts, and, in the future, also electronics. We anticipate that such an integrated mold/surface micromachining/electronics process will offer versatile high-aspect-ratio micromachined structures that can be batch- fabricated and monolithically integrated into complex microelectromechanical systems.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Carole Craig Barron, Carole Craig Barron, James G. Fleming, James G. Fleming, Stephen Montague, Stephen Montague, Jeffry J. Sniegowski, Jeffry J. Sniegowski, Dale L. Hetherington, Dale L. Hetherington, } "Integrated mold/surface-micromachining process", Proc. SPIE 2722, Smart Structures and Materials 1996: Smart Electronics and MEMS, (20 May 1996); doi: 10.1117/12.240455; https://doi.org/10.1117/12.240455


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