Chen-Chih Fan

Differential micro-Pirani gauge for monitoring MEMS wafer-level package

The implementation of differential Pirani gauge for accurately measuring wafer-level package pressures was demonstrated. We proposed a multiple-sensor-solution, where two Pirani gauges were constructed under different pressures; one in sealed micro-cavity for measuring pressures and the other one in opened micro-cavity as a reference. Ambient pressure, structural dimension variations, and resistivity differences among wafers/lots, were captured through the differential scheme for error compensations, allowing accurate pressure determinations. Presented Pirani utilized small gaps (~2μm) between heater and dual heat sinks to obtain wide operation range (0.05~100 Torr) and high sensitivity (~10000 ppm/Torr). With 5X error reductions and high stabilities, the proposed device was successfully used in examining reliabilities and monitoring processes of wafer-level packages.

Self-aligned vertical electrostatic comb drives for scanning micromirrors

A novel method for fabricating a self-aligned electrostatic dual comb drive using a multi-layer SOI process has been developed. The present method utilizes four aligned masks greatly simplifying the existing SOI-MEMS fabrication methods for manufacturing high performance scanning micromirrors. Results from the micromirror device for the novel vertical comb drives show that a mechanical tilt angle of /spl plusmn/1/spl deg/ at 100 V/sub DC/ was achieved for a 450 /spl mu/m diameter micromirror. The scanning micromirror can scan a large angle 62/spl deg/ at the resonance frequency of 10.46 KHz with a sinusoidal voltage input of 60 V in amplitude.