Influences of Magnesium and Zinc Contaminations on Dielectric Breakdown Strength of MOS Capacitors

Makoto TAKIYAMA  Susumu OHTSUKA  Tadashi SAKON  Masaharu TACHIMORI  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E77-C   No.3   pp.464-472
Publication Date: 1994/03/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Quarter Micron Si Device and Process Technologies)
Category: Process Technology
Keyword: 
silicon dioxide,  dielectric breakdown,  metal contamination,  magnesium,  zinc,  

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Summary: 
The dielectric breakdown strength of thermally grown silicon dioxide films was studied for MOS capacitors fabricated on silicon wafers that were intentionally contaminated with magnesium and zinc. Most of magnesium was detected in the oxide film after oxidation. Zinc, some of which evaporated from the surface of wafers, was detected only in the oxide film. The mechanism of the dielectric degradation is dominated by formation of metal silicates, such as Mg2SiO4 (Forsterite) and Zn2SiO4 (Wilemite). The formation of metal silicates has no influence on the generation lifetime of minority carriers, however, it provides the flat-band voltage shift less than 0.3 eV, and forces to increase the density of deep surface states with the zinc contamination.