The mechanism of HF/H2O chemical etching of SiO2

被引:107
作者
Kang, JK [1 ]
Musgrave, CB
机构
[1] Stanford Univ, Dept Mat Sci & Engn, Stanford, CA 94305 USA
[2] Stanford Univ, Dept Chem Engn & Mat Sci & Engn, Stanford, CA 94305 USA
关键词
D O I
10.1063/1.1420729
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Quantum chemistry is used to investigate the HF/H2O chemical etching mechanism of silicon dioxide. Etching proceeds through four sequential steps to remove silicon as SiF4(g) for silicon dioxide, eventually leading to a fluorine-terminated silicon surface which HF attacks, resulting in a hydrogen-passivated silicon surface. Our predicted activation barriers show that the concerted attack by HF and H2O enhances the etch rate over etching by HF alone by reducing the barrier for each etching step. This is consistent with experimental observations that HF etching is enhanced by the presence of water. The QCISD barrier for the rate-limiting step of this catalytic HF/H2O etching mechanism is 22.1 kcal/mol, while the QCISD etching barrier for HF etching is 35.1 kcal/mol. In addition, we find that the F-terminated silica surface is not readily hydrolyzed by exposure to water since the forward barrier of 32.1 kcal/mol for hydrolysis of F-terminated silicon dioxide is larger than the reverse barrier of 26.2 kcal/mol. (C) 2002 American Institute of Physics.
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页码:275 / 280
页数:6
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