CMU MEMS Laboratory Publication Abstract


in Technical Digest of the Solid-State Sensor, Actuator and Microsystems Workshop (Hilton Head), pp. 63-68, June 22-25, 1992, Hilton Head Island, SC, USA.
Thermal Assembly of Polysilicon Microstructures with Narrow-Gap Electrostatic Comb Drive
G. Fedder, J. C. Chang and R. T. Howe
New surface micromachined, polysilicon fuse and weld micro-structures are modeled, fabricated, and characterized. The current required to cut the thin 2000Å fuse is a 30 mA, compared to 80 mA for a 2 µm-thick fuse. For large currents, a simple model shows that the time to cut a fuse is inversely proportional to the square of the current. An aluminum microbrigde is used to form a robust weld, connecting two polysilicon structures. The surface tension of the molten Al produces a force approximately 15 μN, which is about 100 times larger than electrostatic comb drive forces. A series of current pulses is used to melt the Al without destroying the weld joint. A two-dimensional temperature distribution, calculated using a custom finite element program, is helpful in design of the welding structure. One application incorporating both the fusing and welding process is a microactuator connected to a highly compliant suspension. The most aggressive design will move 11 μm with 10 V applied to a 1μm-gap comb drive.
© 1992 Transducers Research Foundation. All Rights Reserved.
Full paper (PDF) (opens in new window).

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