Morris B.G., May G.S
Georgia Institute of Technology, US
Keywords: ANSYS, micromachined sensor, reactive ion etching, real-time control, resonant frequency
This paper explores a novel technique for monitoring film thickness in reactive ion etching that incorporates a micromachined sensor. The prototype sensor correlates film thickness with the change in resonant frequency that occurs in the micromachined platform during etching. The prototype sensor consists of a platform that is suspended over a drive electrode on the surface of the substrate and electrically excited into resonance. As material is etched from the platform, its resonant vibrational frequency shifts by an amount proportional to the amount of material etched, allowing etch rate to be inferred. The micromachined sensor is simulated using ANSYS 7.0. Simulation shows a direct correlation between platform film thickness and resonant frequency, as well as between the platform thickness and its capacitance. Modeling the sensor as a variable capacitor in an auto-zeroing floating gate amplifier (AFGA) circuit using HSPICE reveals that the deflections of the platform are amplified as expected
Journal: TechConnect Briefs
Volume: 1, Technical Proceedings of the 2004 NSTI Nanotechnology Conference and Trade Show, Volume 1
Published: March 7, 2004
Pages: 418 - 421
Industry sector: Sensors, MEMS, Electronics
Topics: MEMS & NEMS Devices, Modeling & Applications, Sensors - Chemical, Physical & Bio
ISBN: 0-9728422-7-6