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Low Stress Cap for Gallium Arsenide Annealing

IP.com Disclosure Number: IPCOM000050333D
Original Publication Date: 1982-Oct-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 21K

Publishing Venue

IBM

Related People

Andrade, TL: AUTHOR

Abstract

As gallium arsenide is annealed, it dissociates unless a capping layer is provided to prevent this. Most capping layers cause a mechanical stressing on the surface of the gallium arsenide because of a differential coefficient of thermal expansion. The present structure, which is described below, provides an annealing cap with good integrity and also has a minimum differential coefficient of thermal expansion.

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Low Stress Cap for Gallium Arsenide Annealing

As gallium arsenide is annealed, it dissociates unless a capping layer is provided to prevent this. Most capping layers cause a mechanical stressing on the surface of the gallium arsenide because of a differential coefficient of thermal expansion. The present structure, which is described below, provides an annealing cap with good integrity and also has a minimum differential coefficient of thermal expansion.

The figure shows a gallium arsenide (GaAs) substrate 1 into which has been ion implanted a region of dopants 2. Normally, the dopant region must be thermally annealed in order to obtain the optimum doping characteristics. In order to prevent the out-gassing of the dopants from the region 2 during the annealing process, a 50 to 100 Angs. thick layer of silicon oxide (SiOx), being a mixture of silicon monoxide and silicon dioxide, is deposited as the layer 3 on the surface of the substrate 1. Then on top of the silicon oxide layer 3, there is deposited a 50 to 100 Angstroms thick layer of polycrystalline gallium arsenide as the layer 4. The gallium arsenide layer 4 serves to cap the substrate during the annealing process, since it is substantially impervious to the passage of dopant atoms. The intermediate layer 3 of silicon oxide is used as a release agent to enable the simplified removal of the gallium arsenide layer 4 from the gallium arsenide substrate 1. The composite layers of polycrystalline gallium arsenide...