Texas Instruments Corporation

Der'E Jan

Thomas M Parrill

Brian Keith Kirkpatrick

Sue E Crank

Shawn T Walsh

James B Friedmann

Byron T Ahlburn

John E Campbell

Joshua J Robbins

A nitride wet etch in which liquid TEOS is flowed directly into the hot phosphoric acid bath before wafer etching begins. This preloads the bath chemistry with silicate ions, and thus helps assure very high selectivity to silicon oxides.

Selective nitride etching with silicate ion pre-loading

A method is given for removing excess oxide from active areas after shallow trench isolation, without the use of chemical-mechanical polishing. A nitride mask protects active areas during the etch of isolation trenches. The trenches are filled with oxide, using high density plasma deposition, which simultaneously etches, providing a sloping contour around the isolation trenches. A further layer of nitride is used to provide a cap over the trench which seals to the underlying layer of nitride. The cap layer of nitride receives a patterned etch to remove the cap only over the active areas. This allows a selective etch to remove the excess oxide, which can be followed by a selective etch to remove the nitride layers.

Method for trench isolation of semiconductor devices

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Der'E Jan