Anisotropic wet etching of silicon

Details Anisotropic wet etching of silicon Anisotropic wet etching of silicon

2007-09-18

2007-09-18

Ahmed, Shamim (Department: 1765)

Etching a substrate: processes

Nongaseous phase etching of substrate

Etching inorganic substrate

C216S041000, C216S083000, C438S745000

Reexamination Certificate

active

10773244

ABSTRACT:
A silicon oxide film is formed on one principal surface of a silicon substrate by thermal oxidation, and thereafter, a silicon nitride film is formed on the silicon oxide film by CVD. A lamination layer of the silicon oxide film and silicon nitride film is selectively dry etched to form a mask opening22and leave an etching mask made of a left region of the lamination layer. The substrate is selectively and anisotropically etched with alkali etchant such as TMAH by using the etching mask to form a substrate opening. By setting a ratio of the thickness of the silicon oxide film to the thickness of the silicon nitride film to 1.25 or larger or preferably 1.60 or larger, it is possible to prevent the deformation of the etched shape of the inner walls of the openings and cracks in the etching mask.

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