Importance

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Abstract

At least one through opening of predetermined location and dimensions is fabricated in a (100) silicon wafer by orientation dependent etching method after completion of integrated circuits on the wafer, the opening extending through the wafer between a circuit surface of the wafer and an opposite parallel base surface of the wafer and having a predetermined location relative to the integrated circuit on the circuit surface of the wafer. The method includes the steps of fabricating the integrated circuit on the circuit surface of the wafer; applying an etch resistant layer of plasma solicon nitride on the circuit and base surfaces of the wafer; patterning the etch resistant plasma silicon nitride layer on the circuit surface to define an upper etch opening having a location and dimensions which define the predetermined location and dimensions of the through opening; and patterning the plasma silicon nitride layer on the base surface to produce a lower etch opening aligned with the upper etch opening within a predetermined tolerance. The wafer is then anisotropically etched to produce a first recess corresponding to the upper etch opening in the circuit surface and a second recess corresponding to the lower etch opening in the base surface, each of the first and second recesses being bounded by (111) plane side walls. The anisotropic etching of the second recess intersects the first recess to form the through opening bounded by (111) plane side walls and has its predetermined dimensions and location defined by the patterning of the upper etch opening.

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First Claim