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Hydrogen Plasma Cleaning of the Si(100) Surface: Removal of Oxygen and Carbon and The Etching of Si

Published online by Cambridge University Press:  21 February 2011

David Kinosky
Affiliation:
Microelectronics Research Center, The University of Texas, Austin, TX 78712
R. Qian
Affiliation:
Microelectronics Research Center, The University of Texas, Austin, TX 78712
A. Mahajan
Affiliation:
Microelectronics Research Center, The University of Texas, Austin, TX 78712
S. Thomas
Affiliation:
Microelectronics Research Center, The University of Texas, Austin, TX 78712
P. Munguía
Affiliation:
Microelectronics Research Center, The University of Texas, Austin, TX 78712
J. Fretwell
Affiliation:
Microelectronics Research Center, The University of Texas, Austin, TX 78712
S. Banerjee
Affiliation:
Microelectronics Research Center, The University of Texas, Austin, TX 78712
A. Tasch
Affiliation:
Microelectronics Research Center, The University of Texas, Austin, TX 78712
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Abstract

Silicon etch rates and the in situ remote H plasma cleaning effectiveness in a Remote Plasma-enhanced Chemical Vapor Deposition (RPCVD) system have been measured under conditions of varying substrate temperature, exposure time, and hydrogen pressure. An incubation phenomenon is observed in the Si etch rate as a function of exposure time to the plasma species at a substrate temperature of 250°C. The etch rate is observed to increase from 20 Å/hr. for 45 min. exposure to 70 Å/hr. for a 4 hour exposure. The dependence of the etch rate on the plasma discharge pressure shows the etch rate to decrease from 72 Å/hr. at 50-55 mTorr to 4 Å/hr. for pressures greater than 125 mTorr. The substrate temperature is found to have the greatest effect on both the cleaning of the surface and the Si etch rate, with 250ÅC resulting in a surface with oxygen and carbon concentrations less than the detection limit for Auger Electron Spectroscopy. On wafers exposed to atomic H at both 150 and 400ÅC, oxygen, carbon and nitrogen were detected after 4 hr. exposures. The etch rate is inversely related to temperature, consistent with earlier results. At a substrate temperature of 150ÅC, Reflection High Energy Electron Diffraction (RHEED) shows the diffraction pattern to change from a streak pattern observed at higher temperatures to a spot pattern, indicating a roughened surface after 4 hrs. of etching. Wafers cleaned at temperatures above 150ÅC yielded streak patterns even after 4 hr. exposure. Increasing the H pressure during the clean had no effect on the final RHEED pattern.

Type
Research Article
Copyright
Copyright © Materials Research Society 1993

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References

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