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Selectively Etching Semiconductor Material

IP.com Disclosure Number: IPCOM000094235D
Original Publication Date: 1966-Jul-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Biedermann, E: AUTHOR

Abstract

This method selectively etches areas of silicon carbide. Silicon carbide is so etch resistant that it is not attacked by most known etches. This presents a particular problem when it is desired to attach contacts to a region of one conductivity type which is below a region of another conductivity type.

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Selectively Etching Semiconductor Material

This method selectively etches areas of silicon carbide. Silicon carbide is so etch resistant that it is not attacked by most known etches. This presents a particular problem when it is desired to attach contacts to a region of one conductivity type which is below a region of another conductivity type.

In drawing 1, there is shown a monocrystalline wafer of silicon carbide 1 forming the body of a semiconductor component which is doped to produce a P- type conductivity in it. On the surface of wafer 1, a thin N-type conductivity layer 2 is produced by diffusion or by epitaxial deposition. Because it is necessary to expose layer 2 for the attachment of contacts to it, masking layers, which might customarily be used, cannot be used because they are attacked by the etchants normally required to etch silicon carbide. To eliminate the necessity for highly reactive etches, platinum is reacted with the silicon carbide at a high temperature so that it dissolves in the silicon carbide.

A layer of platinum 3 is deposited on N-type layer 2 by evaporation of platinum through metal masks not shown. The latter define the area to be covered by the platinum. Upon heating, layer region 3 dissolves in the silicon carbide forming a platinum-silicon carbide region 4. This penetrates through layer 2 to layer 1 as in drawing 2. The depth to which region 4 penetrates is determined by the quantity of the applied material, the reaction time and t...