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Reactive Ion Etching of Submicron Silicon Grooves

IP.com Disclosure Number: IPCOM000046428D
Original Publication Date: 1983-Jul-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Greschner, J: AUTHOR [+2]

Abstract

When submicron silicon grooves are etched with reactive ions, using a silicon dioxide etch mask with vertical side walls, etch defects occur in the form of a dovetailing of the upper region of the groove. These etch defects are attributable to single or multiple molecule reflection at the silicon dioxide mask, with the extent of such defects being determined by the etch time, the size of the etch angles formed at the mask and their distance from the silicon substrate.

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Reactive Ion Etching of Submicron Silicon Grooves

When submicron silicon grooves are etched with reactive ions, using a silicon dioxide etch mask with vertical side walls, etch defects occur in the form of a dovetailing of the upper region of the groove. These etch defects are attributable to single or multiple molecule reflection at the silicon dioxide mask, with the extent of such defects being determined by the etch time, the size of the etch angles formed at the mask and their distance from the silicon substrate.

The figures show an originally vertical silicon dioxide mask (Fig. 1A) and its condition after the silicon groove has been etched (Fig. 1B). The lower portion of the mask is vertical as the original mask; this is followed by a portion with an angle of about 83 and, finally, by a portion with an angle of about 45. Both angles are preferential sputter etch angles from which the etch molecules are scattered. They are essentially formed by the argon ions of the Ar/Cl2 plasma. It has been found that only the ions scattered from the steep 83 angle of the mask have an angular distribution causing indentations to be etched at the opposite groove wall. The narrower these grooves, the more these indentations are localized in the upper region of the grooves. In the case of grooves etched for dielectric isolation of semiconductor devices, the indentations may lead to incomplete filling of the grooves during thermal oxidation.

To reduce the etch defects to a tole...