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High-Low Epitaxial Process Under Reduced Pressures

IP.com Disclosure Number: IPCOM000047565D
Original Publication Date: 1983-Dec-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Srinivasan, GR: AUTHOR

Abstract

A high-low epitaxial process has allowed the reduction of epitaxial temperatures for silicon depositions. However, at decreased deposition temperatures, a certain amount of autodoping still remains although it is considerably reduced by the process. The reduced-pressure epitaxial process helps in reducing this autodoping problem especially for N type dopants in silicon. The typical reduced-pressure epitaxial process uses a SiH2Cl2 epitaxial growth at 1080ŒC. The epitaxial quality of layers grown by this technique remains a problem. The following procedures overcome these problems. After loading the epitaxial reactor with silicon wafers, the reactor is preheated in H2 to heat the silicon wafers at reduced pressures in the range of 0.1 - 0.

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High-Low Epitaxial Process Under Reduced Pressures

A high-low epitaxial process has allowed the reduction of epitaxial temperatures for silicon depositions. However, at decreased deposition temperatures, a certain amount of autodoping still remains although it is considerably reduced by the process. The reduced-pressure epitaxial process helps in reducing this autodoping problem especially for N type dopants in silicon. The typical reduced- pressure epitaxial process uses a SiH2Cl2 epitaxial growth at 1080OEC. The epitaxial quality of layers grown by this technique remains a problem. The following procedures overcome these problems. After loading the epitaxial reactor with silicon wafers, the reactor is preheated in H2 to heat the silicon wafers at reduced pressures in the range of 0.1 - 0.8 atmospheres and at a temperature between 1140-1180OEC, then a chlorosilane gas is flowed through the reactor, and the reactor temperature is then reduced to the appropriate deposition temperature in the range of 1000-1100OEC, the epitaxial deposition being allowed to occur at this temperature. The growth rate is maintained at low levels, at least initially, in the range 0.05-0.2 mm/min. by suitably adjusting the source gas flow rate. The source gas could be any of the chlorosilanes but not silane. The process produces several advantages. First, leakage quality of the epitaxy is superior to that produced at higher deposition temperatures. This quality enhancement observed at o...