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AssigneeTexas Instruments Incorporated
InventorsVladimir F. Drobny, Kevin X. Bao
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An epitaxial layer is formed on a P type silicon substrate in which a plurality of P+ buried layer regions, a plurality of N+ buried layer regions, and a P+ field layer region occupying most of the substrate surface are diffused. The substrate is loaded in a reactor with a carrier gas. The substrate is pre-baked at a temperature of approximately 850° C. As the substrate is heated to a temperature of 1050° C., N+ dopant gas is injected into the carrier gas to suppress auto doping due to P+ atoms that escape from the P+ buried layer regions. The substrate is subjected to a high temperature bake cycle in the presence of the N+ dopant gas. A first thin intrinsic epitaxial cap layer is deposited on the substrate, which then is subjected to a high temperature gas purge cycle at 1080° C. A second thin intrinsic epitaxial cap layer then is deposited on the first, and a second high temperature gas purge cycle is performed at 1080° C. Then an N−epitaxial layer is deposited on the second cap layer at 1080° C. The harmful effects of a dip in the dopant concentration profile at the bottoms of the collectors of the NPN transistors are avoided by the process.
A method of making an epitaxial layer on a silicon substrate having in a major surface thereof a P+ field layer region in a substantial portion of the major surface, comprising:
A method of making an epitaxial layer on a P type silicon substrate having in a major surface thereof a plurality of P+ buried layer regions, a plurality of N+ buried layer regions, and also having a P+ field layer region in most of the major surface, comprising:
A method of making an epitaxial layer on a substrate having in a major surface thereof a P+ field layer region in a substantial portion of the major surface, comprising:
A method of making an epitaxial layer on a substrate having in a major surface thereof a P+ field layer region in a substantial portion of the major surface, comprising:
Dependencies are inferred from the claim text.