Light nitrogen implant for preparing thin-gate oxides
- 1 March 1997
- journal article
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Electron Device Letters
- Vol. 18 (3), 105-107
- https://doi.org/10.1109/55.556095
Abstract
We have implanted nitrogen (N/sup +/) into Si substrates before growing thin thermal oxides, and discovered that light N/sup +/ doses of 5×10/sup 13/-5×10/sup 14//cm 2 reduced the oxidation rates by 20-30%. High-resolution TEMs and multiangle ellipsometry were used to study the oxides. The TEM reveals a highly uniform transition from the crystalline Si to the amorphous SiO 2 . With a fixed index of refraction at 1.458 for the ellipsometry, the two measurements gave identical oxide thickness between 25 and 144 /spl Aring/, in contrast to the previously suggested 1.7 for oxides thinner than 100 /spl Aring/. In addition, the oxidation retardation was accompanied with an improvement of the oxide uniformity across the 6-in Si wafers. We also present results of n-channel MOSFETs with coded channel lengths varying from 0.2 μm to 3 μm. The implications of these findings in terms of VLSI technologies and oxidation chemistry are discussed.Keywords
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