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UNIFORM SILICON ETCHING USING CF4 AND CClF3 MIXTURE

IP.com Disclosure Number: IPCOM000040680D
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Bennett, RS: AUTHOR [+3]

Abstract

It has been found that by using a mixture of CF4 and CClF3 in reactive ion etching (RIE) of silicon, the uniformity of etch is substantially improved compared to using CF4 or CClF3 alone. In general, using RIE with CF4 alone, the etch rates at the edge of the wafer or the outer edge of the electrode are substantially higher than in the middle. The net result is an etch non-uniformity on the order of plus or minus twenty percent. By adding as little as one to two percent of a chlorinated fluorocarbon, such as CClF3 or CCl2F2, the uniformity can be improved to plus or minus five percent. Similar results can be obtained by passivating the reactor walls with polymer deposits and causing the chlorinated fluorocarbon species to be absorbed on the walls by means of a discharge.

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UNIFORM SILICON ETCHING USING CF4 AND CClF3 MIXTURE

It has been found that by using a mixture of CF4 and CClF3 in reactive ion etching (RIE) of silicon, the uniformity of etch is substantially improved compared to using CF4 or CClF3 alone. In general, using RIE with CF4 alone, the etch rates at the edge of the wafer or the outer edge of the electrode are substantially higher than in the middle. The net result is an etch non-uniformity on the order of plus or minus twenty percent. By adding as little as one to two percent of a chlorinated fluorocarbon, such as CClF3 or CCl2F2, the uniformity can be improved to plus or minus five percent. Similar results can be obtained by passivating the reactor walls with polymer deposits and causing the chlorinated fluorocarbon species to be absorbed on the walls by means of a discharge. Other compositions of fluorocarbons or volatile chloroalkanes may also produce the same effect. References 1 U.S. Patent 4,583,106. 2 U.S. Patent 4,551,906. 3 U.S. Patent 4,546,536.

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