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Optical And Mass Spectrometric Diagnostic Methods For Plasma Etching

Published online by Cambridge University Press:  15 February 2011

V. M. Donnelly
V. M. Donnelly*
Affiliation:
AT&T Bell Laboratories, 600 Mountain Ave., Murray Hill, NJ 07974
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Abstract

Optical emission and line-of-sight mass spectrometry were used to monitor Cl, Cl2 and SiClx reaction products during etching of Si(100) in a high density (1–2 × 1011 ions/cm3) chlorine plasma. Emission from atomic Cl, and from ion-pair states of C12 at 7.2 – 9.4 eV were monitored, along with emission from a small amount of Xe that was added to the gas to sense changes in the electron energy distribution (i.e. actinometry). In this manner, the normalized emissions provide a measure of relative number densities of C12 and Cl. These measurements were converted into absolute numbers by extending the measurements to extremely low powers, where C12 and Xe number densities are known. These results are compared with those recorded with a differentially pumped, line-of-sight mass spectrometer. At power densities of ˜0.5 W/cm3, the discharge is almost completely dissociated in the plasma source region (˜90%), while above the wafer and downstream of the plasma, the percent consumption of Cl2 drops to 75%. A long term upward drift in the percent dissociation in the source was observed, attributable to a time-dependent decrease in the rate of Cl-atom recombination on the glass walls. These results are compared with recent model predictions and are also discussed in terms of their significance for surface etching reactions, and real-time control.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 406: Symposium L – Diagnostic Techniques for Semiconductor Materials Processing , 1995 , 3
Copyright
Copyright © Materials Research Society 1996

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References

REFERENCES

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