Plasma etching processes for the realization of micromechanical structures for MEMS. (MoO3 )x thin films.

A K Paul, A K Dimri, R P Bajpai


Plasma-assisted etching technology has been used for the development and fabrication of silicon-based micromechanical structures for the realization of microelectro mechanical systems (MEMS). This paper reports on the reactive ion etching in fluorocarbon gases such as SF6, CHF3 and their mixtures with O2, Ar for high fidelity pattern transfer from patterns delineated in positive photo-resist into underlying substrates (i.e. Si, SiO2). SiO2 layer has been etched in CHF3/Ar gas plasma and the effect of rf power and CHF3 gas flow in Ar (5 sccm) on the etch rates has been studied. SiO2 etch rates in the range 50 300 �/min have been obtained at different process parameters. Nearly vertical side walls in SiO2 have been achieved at 100 watts of RF power (DC bias = -210 volts) and 30 scccm CHF3+5 sccm Ar gas flow rate at 6 mtorr having SiO2 etching rate of 150 �/min. Microgears of diameter 50 mm and linear grating type pattern with 1.8 mm periodicity having etching depths of 2.6 mm have been realized in SiO2. Patterns have also been etched in silicon using SF6/O2/CHF3 with nearly vertical walls. 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.


Plasma etching; micromechanical structures; reactive ion etching. .pressure sensor

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