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Shallow Isolation Trench Etching

IP.com Disclosure Number: IPCOM000037924D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Jost, ME: AUTHOR [+3]

Abstract

Shallow isolation trenches in silicon substrates can be etched with rounded bottom corners having decreased stress and leakage by swelling the photoresist masking prior to etching.

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Shallow Isolation Trench Etching

Shallow isolation trenches in silicon substrates can be etched with rounded bottom corners having decreased stress and leakage by swelling the photoresist masking prior to etching.

In Fig. 1, isolation trenches 1 of approximately 0.5 um. depth are formed in substrate 2 by defining the trenches with an organic photoresist 3 having a high surface adsorption rate and etching the trenches with a silicon-containing chlorinated gas, silicon tetrachloride. While the chlorinated plasma etches the silicon, the silicon-rich component of the etchant saturates the organic resist surface 4.

As a second step, an optimized combination of oxygen plasma and hydrochloric acid is used as the etchant. The saturated silicon-rich photoresist 4 transforms to silicon dioxide of increasing thickness, thus narrowing the effective etch area at the trench bottom 5 to thereby form curved corners 6, as seen in Fig.
2.

Disclosed anonymously.

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