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Browse Prior Art Database

Obtaining Improved Gas Flow in Diffusion Apparatus

IP.com Disclosure Number: IPCOM000076233D
Original Publication Date: 1972-Feb-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Viva, OR: AUTHOR

Abstract

This system of baffles produces essentially laminar flow in diffusion tubes which results in greater uniformity of impurity distribution within the wafers.

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Obtaining Improved Gas Flow in Diffusion Apparatus

This system of baffles produces essentially laminar flow in diffusion tubes which results in greater uniformity of impurity distribution within the wafers.

In flow through diffusion apparatus without baffles the distribution of gas horizontally across the tube is nonuniform. In general, the gas will drop to the bottom of the diffusion tube due to gravity effect causing impurity variations in the diffused regions across the wafers. This baffle structure consists of a set of double V baffles 10 in tandem with a second set of parallel horizontal plates 12. The double V baffles are positioned in a generally vertical plane in tube 14 with the plates arranged horizontally in close proximity. Gas flowing from inlet 16 is intimately mixed by the baffles 10 and is, thereafter, caused to assume laminar flow by baffles 10 as the gas passes over wafer boat 18.

The baffle structure is particularly useful in diffusions using POCl(3) gas and has significantly improved the uniformity of the sheet resistance of the resultant wafers.

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