Large-scale metal MEMS mirror arrays with integrated electronics Thomas Bifano', Paul Bierden2, Steven Cornelissen1, Clara Dimas2, Hocheol Lee1, Michele Miller3, and Julie Perreault1 'Boston University, College of Engineering 2Boston Micromachines Corporation, Watertown, MA 3Michigan Technological University Abstract Design, microfabrication, and integration of a micromachined spatial light modulator (pSLM) device are described. A large array of electrostatically actuated, piston-motion MEMS mirror segments make up the optical surface of the tSLM. Each mirror segment is capable of altering the phase of reflected light by up to one wavelength for infrared illumination (X = 1.5 pm), with 4-bit resolution. The device is directly integrated with complementary metal-oxide semiconductor (CMOS) electronics, for control of spatial optical wavefront. Integration with electronics is achieved through direct fabrication of MEMS actuators and mirror structures on planarized foundry-type CMOS electronics. Technical approaches to two significant challenges associated with manufacturing the j.SLM are discussed: integration of the MEMS array with the electronicdriver array and production of optical-quality mirror elements using a metal-polymer surface micromachining process. Introduction Large arrays of micromachined piston-motion mirrors are required for laser communication and optical correlation applications. Such devices can be used to rapidly modify the spatial phase of a coherent wavefront. Spatial phase modulation has been possible for some years, primarily through the use of liquid crystal phase devices. MEMS-based spatial light modulators promise orders-of-magnitude higher speed, enabling the use of SLMs in applications such as pattern recognition and laser communication, which typically require faster response than is achievable using liquid crystal devices. To control large numbers of pixels in a MEMS SLM array it will be necessary that the pixels are addressed through direct integration, rather than off-chip addressing through wire bond connections. Such integrationposes a system-level design challenge since silicon foundry MEMS processes are in general incompatible with prefabricated CMOS electronics (due to the high temperature processing required in MEMS fabrication). A MEMS fabrication alternative based on metal micromachining has proven successfulin the past for production of large micromirror arrays, most notably for the Texas Instruments Digital Light Processor®.In the work described here, a process similar to that used for the TI-DLP is proposed, using foundry electronics chips as the MEMS substrate and employing low-temperature metal/polymer thin-film surface micromachining for MEMS device fabrication. Design, Test, Integration, and Packaging of MEMS/MOEMS 2002, Bernard Courtois, Jean Michel Karam, Karen W. Markus, Bernd Michel, Tamal Mukherjee, James A. Walker, Editors, Proceedings of SPIE Vol. 4755 (2002) © 2002 SPIE · 0277-786X/02/$15.00 467