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Modified Ultrasonic Rinse for Removal of Film Particulates

IP.com Disclosure Number: IPCOM000047812D
Original Publication Date: 1983-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Ahlgren, DC: AUTHOR [+3]

Abstract

LPCVD (low pressure chemical vapor deposition) films, particularly low temperature (430Œ) pyrolytic SiO2 films, are susceptible to problems from particulates generated in the gas phase reaction and upon cooling of the deposition boat. These particulates can result in emitter-to-base shorts after contact metallurgy is deposited, and possibly be related to degradation of advanced transistor processes. Most of these particulates are found to reside at the top of the deposited film (not incorporated into the layer). To eliminate or reduce these particulates, it is proposed to remove these particulates using a "modified" ultrasonic rinse technique. While felt-cleaning methods are effective for eliminating particulates in simpler processes, increased topology introduced in polysilicon base technologies makes this solution inoperable.

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Modified Ultrasonic Rinse for Removal of Film Particulates

LPCVD (low pressure chemical vapor deposition) films, particularly low temperature (430OE) pyrolytic SiO2 films, are susceptible to problems from particulates generated in the gas phase reaction and upon cooling of the deposition boat. These particulates can result in emitter-to-base shorts after contact metallurgy is deposited, and possibly be related to degradation of advanced transistor processes. Most of these particulates are found to reside at the top of the deposited film (not incorporated into the layer).

To eliminate or reduce these particulates, it is proposed to remove these particulates using a "modified" ultrasonic rinse technique. While felt-cleaning methods are effective for eliminating particulates in simpler processes, increased topology introduced in polysilicon base technologies makes this solution inoperable. Conventional ultrasonics have been seen to result in structural damage to oxides and overhanging topologies. This proposed system contemplates using ultrasonic rinse with the following modifications to remove CVD-generated particulates while minimizing structural damage. Damage has been shown to be a result of high amplitude regions within the bath which occur when standing sound waves are present. This can be circumvented by oscillating the boat containing the wafers at frequencies of 0.1-1 Hz. This reduces exposure of any one area on the wafer to prolonged exposure to the high a...