Flip-chip fabrication of advanced micromirror arrays

• Published in: Technical Digest. MEMS 2001. 14th IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.01CH37090) pp. 313 - 316
• Main Authors: Michalicek, M.A., Bright, V.M.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2001
• Subjects: Assembly; Bonding; Fabrication; Foundries; Micromechanical devices; Micromirrors; Mirrors; Pistons; Rough surfaces; Surface roughness
• ISBN: 9780780359987; 0780359984
• ISSN: 1084-6999
• DOI: 10.1109/MEMSYS.2001.906541

This paper describes the design, fabrication, and testing of advanced micromirror arrays created using a novel, inexpensive, simple, reliable, and repeatable flip-chip assembly technique. The arrays are assembled by flip-chip bonding the upper structural layers of a micromirror array chip to the lower structural layers of a submount receiving chip using a custom built flip-chip bonding machine. Each chip is commercially prefabricated in the MUMPS process and then flip-chip bonded to form the working arrays such that many of the typical adverse effects of surface-micromachining were removed. Several arrays of piston and cantilever micromirror devices were flip-chip fabricated using this technique. These arrays demonstrated unprecedented features including 98% active surface area, five structural layers, less than 2 nm of RMS surface roughness per device, less than 80 nm of peak planarity variance across 1 mm arrays, address potentials compatible with CMOS control electronics and built-in masking capabilities for deposition of reflective materials. This work demonstrates that the demanding requirements of most micromirror applications can be met using a fast, simple, and low-cost technique that produces devices superior to those fabricated using far more costly techniques.