Fabrication of five-level ultraplanar micromirror arrays by flip-chip assembly

M. Adrian Michalicek; Victor M. Bright

doi:10.1117/12.443098

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2 October 2001 Fabrication of five-level ultraplanar micromirror arrays by flip-chip assembly

M. Adrian Michalicek, Victor M. Bright

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Proceedings Volume 4561, MOEMS and Miniaturized Systems II; (2001) https://doi.org/10.1117/12.443098
Event: Micromachining and Microfabrication, 2001, San Francisco, CA, United States

Abstract

This paper reports a detailed study of the fabrication of various piston, torsion, and cantilever style micromirror arrays using a novel, simple, and inexpensive flip-chip assembly technique. Several rectangular and polar arrays were commercially prefabricated in the MUMPs process and then flip-chip bonded to form advanced micromirror arrays where adverse effects typically associated with surface micromachining were removed. These arrays were bonded by directly fusing the MUMPs gold layers with no complex preprocessing. The modules were assembled using a computer-controlled, custom-built flip-chip bonding machine. Topographically opposed bond pads were designed to correct for slight misalignment errors during bonding and typically result in less than 2 micrometers of lateral alignment error. Although flip-chip micromirror performance is briefly discussed, the means used to create these arrays is the focus of the paper. A detailed study of flip-chip process yield is presented which describes the primary failure mechanisms for flip-chip bonding. Studies of alignment tolerance, bonding force, stress concentration, module planarity, bonding machine calibration techniques, prefabrication errors, and release procedures are presented in relation to specific observations in process yield. Ultimately, the standard thermo-compression flip-chip assembly process remains a viable technique to develop highly complex prototypes of advanced micromirror arrays.

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M. Adrian Michalicek and Victor M. Bright "Fabrication of five-level ultraplanar micromirror arrays by flip-chip assembly", Proc. SPIE 4561, MOEMS and Miniaturized Systems II, (2 October 2001); https://doi.org/10.1117/12.443098

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