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Arsenic Doped Oxide Subcollector Process to Prevent B Cristobalite Formations

IP.com Disclosure Number: IPCOM000085505D
Original Publication Date: 1976-Apr-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Fuertinger, RE: AUTHOR [+3]

Abstract

B-cristobalites are hexagonal crystalline structures approximately 500 microinches in diameter. These crystalline defects are caused by arsenic compounds combining with the silicon from the substrate through defects in the silicon dioxide diffusion barrier.

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Arsenic Doped Oxide Subcollector Process to Prevent B Cristobalite Formations

B-cristobalites are hexagonal crystalline structures approximately 500 microinches in diameter. These crystalline defects are caused by arsenic compounds combining with the silicon from the substrate through defects in the silicon dioxide diffusion barrier.

The use of a diffusion barrier of silicon nitride/pyrolytic oxide eliminates the formation of B-cristobalites outside of the subcollector area. The optimum range has been found to be 1200 Angstroms to 1600 Angstroms Si(3)N(4) with 1000 Angstroms pyrolytic SiO(2).

In the process, a 700 Angstrom screen oxide is grown on the silicon substrate and the nitride/pyrolytic oxide is then deposited. Alternatively, a single, in situ deposited, three-layer composite film comprising: pyrolytic oxide, 700 Angstrom, silicon nitride, 1200 Angstrom to 1600 Degrees, and pyrolytic oxide, 1000 Angstroms, may be deposited.

Windows are formed in the composite for the subcollector region. A 700 Angstrom screen oxide is then grown. Arsenic doped oxide (ASG) is then deposited at a low temperature (500 degrees C) followed by a subcollector drive- in at 1150 degrees C in an oxygen ambient. Following the drive-in step, the ASC thermal oxide is completely removed, and the wafer is thermally oxidized to redistribute and delineate the subcollector area.

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