Laser probing of micromachined capacitive pressure sensor silicon membrane.(MoO3 )x thin films.

G Bose, Ravi Shanker, Suneet Tuli


The paper reports the study of vibrations occurring in a thin silicon membrane of a conventional capacity pressure sensor. The 20 m-thick silicon membrane has an area of 6x6 mm. Vibrations induced on the membrane with the help of electrical excitation were studied using a heterodyne laser probe. The probe output gives a measure of the amplitude of vibration of the membrane. Using this technique spatial response of the capacitive pressure sensor diaphragm has been carried out. The resonant frequency peaks of the membrane were measured and the effect of air pressure loading observed.of spincoated film of PMMA on silicon wafer is an important parameter for its use as an etch mask, while etching in aqueous KOH solution for silicon micromachining. Pre- and posttreatments have been performed on silicon substrate and the mask layer to achieve greater adhesion of the mask material. Feasibility is demonstrated of the use of PMMA as etch mask.made to crystallize the thin films at as low a processing temperature as possible. The properties studied include dielectric measurements and hysteresis. Thin films of calcium-modified lead titanate (PCT) were also prepared by the sol gel technique and their pyroelectric characteristics were studied for use in infrared was coated. These results show that the crystalline quality and deposition rate can be controlled over a wide range by this method.


Heterodyne laser probe; displacement measurement silicon membrane; micromachining; capacitive pressure sensor

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