Bulk silicon micromachining for the scanning thermal profiler and other applications

Yogesh B. Gianchandani; Khalil Najafi

doi:10.1117/12.190930

21 October 1994 Bulk silicon micromachining for the scanning thermal profiler and other applications

Yogesh B. Gianchandani, Khalil Najafi

Proceedings Volume 2291, Integrated Optics and Microstructures II; (1994) https://doi.org/10.1117/12.190930
Event: SPIE's 1994 International Symposium on Optics, Imaging, and Instrumentation, 1994, San Diego, CA, United States

Abstract

It has previously been shown that bulk silicon micromachining using a dissolved wafer process with an impurity based etch stop can be used to fabricate structures with variable thickness, high (thickness-to- width) aspect ratios, and overhanging features, as well as structures with multiple stacked levels. This technology has been further extended in the development of silicon micromachined thermal profilers (SMTPs). The SMTP consists of a polysilicon-gold thermocouple located at the tip of a probe shank that overhangs the edge of the substrate. The probe shank is suspended by flexible beams, and can be electrostatically excited into motion by comb drives. A polysilicon heater is built into the base of the shank to provide a thermal bias. As the thermocouple is scanned across a sample, the varying proximity and temperature of features on the sample surface can be mapped as a function of position, providing high resolution topographic and thermographic information. The same principle can also be used in photothermal absorption spectroscopy, microelectronic metrology, and microflow measurements. Advanced versions of the SMTP suspend the thermocouple on a dielectric diaphragm for improved thermal isolation, and replace it with a thermopile for a larger readout signal. Devices have been fabricated using an IC-compatible, 8 mask, single-sided process that has general applicability beyond the SMTP. Preliminary data from test scans is presented.

Citation Download Citation

Yogesh B. Gianchandani and Khalil Najafi "Bulk silicon micromachining for the scanning thermal profiler and other applications", Proc. SPIE 2291, Integrated Optics and Microstructures II, (21 October 1994); https://doi.org/10.1117/12.190930

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