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Integrated Circuit Fabrication Using Anodization

IP.com Disclosure Number: IPCOM000094160D
Original Publication Date: 1966-Jun-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Gray, RK: AUTHOR [+2]

Abstract

In the formation of semiconductor devices by diffusion techniques, there is, conventionally, a series of oxidations of the silicon wafer surface and etchings through the oxidized silicon dioxide surfaces. Such a series of oxidations and etchings produces a surface silicon dioxide layer which is of varying thickness. It is therefore difficult to uniformly etch through this layer the holes necessary for subsequent ohmic contact to the semiconductor devices formed by diffusion in the silicon wafer. The use of anodization as the oxidation process allows the production of a uniform oxide thickness over the entire semiconductor wafer, regardless of the number of reoxidations and etchings.

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Integrated Circuit Fabrication Using Anodization

In the formation of semiconductor devices by diffusion techniques, there is, conventionally, a series of oxidations of the silicon wafer surface and etchings through the oxidized silicon dioxide surfaces. Such a series of oxidations and etchings produces a surface silicon dioxide layer which is of varying thickness. It is therefore difficult to uniformly etch through this layer the holes necessary for subsequent ohmic contact to the semiconductor devices formed by diffusion in the silicon wafer. The use of anodization as the oxidation process allows the production of a uniform oxide thickness over the entire semiconductor wafer, regardless of the number of reoxidations and etchings.

The device is made according to the following procedure. Silicon wafer 1 is oxidized to produce initial silicon dioxide layer 2. A first opening is made in layer 2 and base-collector junction 3 is formed by conventional diffusion techniques. Wafer 1 is then anodized in a suitable electrolyte at room temperature. The current density on the silicon and silicon dioxide surfaces and the potential are controlled so that the resulting silicon dioxide thickness 4 approximately reaches the original layer 2 thickness.

The thickness of the silicon dioxide in the areas of layer 2 is not increased by this anodization. A smaller opening is then etched through layer 3 to allow the formation of emitter-base junction 5 by conventional diffusion techniq...