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A New Purification Method of Fluoric Acid for Vlsi Manufacturing

Published online by Cambridge University Press:  21 February 2011

T. Shimono  and
K. Yamamoto
T. Shimono
Affiliation:
NEC Corporation, 1-1, Miyazaki 4-chome, Miyamae-ku, Kawasaki, Kanagawa 216, Japan.
K. Yamamoto
Affiliation:
NEC Corporation, 1-1, Miyazaki 4-chome, Miyamae-ku, Kawasaki, Kanagawa 216, Japan.
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Abstract

A new purification method was developed in order to remove metallic impurities in HF chemicals (HF, BHF). Metallic impurities having lower ionization tendency than Si, such as Cu, are adsorbed on the silicon wafer surface in these chemicals and degradate device characteristics. Cu removal from these chemicals by the adsorption method was investigated in this work. Granular polysilicon(poly-Si) was examined as the adsorbent. Cu removal by poly-Si was caused by electroless deposition of Cu onto poly-Si surface. When the conventional poly-Si was used as an adsorbent, it was difficult to remove Cu until less than lppb. Cu adsorption efficiency was remarkably improved by the use of poly-Si deposited metal electrodes on its surface(M-poly-Si). Au was preferable as an electrode metal for its chemical stability. Cu was removed until less than 0.01ppb by the use of Au-poly-Si as an adsorbent. HF chemicals were continuously purified by passing an adsorbent packed column which was set in the wet station.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 315: Symposium Y – Surface Chemical Cleaning and Passivation for Semiconductor Processing , 1993 , 327
Copyright
Copyright © Materials Research Society 1993

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References

REFERENCES

1. Shimono, T., Morita, M., Muramatsu, Y. and Tsuji, M., Proceedings of 8th Workshop on ULSI Ultra Clean Technology, (Tokyo, 1990), p.59 Google Scholar