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6763662 
Journal Article 
Mechanism for desorption of SiF4 from an SiO2 film surface in HF solutions 
Oku, T; Sato, K; Otsubo, M; , 
1997 
JAPAN J APPLIED PHYSICS 
MINATO-KU TOKYO 
1374-1379 
WOS:A1997WT45700013 
An extended Huckel calculation was employed to calculate the change in the electron density on the Si-O back bonds and the total electronic energy during the reaction at the SiO2 film surface. We demonstrate that the desorption of SiF4 occurs as follows: (1) bifluoride (HF2-) ions dissociate into HF monomers and F- ions near the surface, (2) F- ions attack the -SiF3 surfaces and hydrogen ions attack the oxygen atoms of the back bond; (3) the O-Si-F bond angle decreases and the Si-O bond strength is weakened, (4) the hydrogen atoms passivate the oxygen atoms after tetrahedral SiF4 molecules are generated and the Si-O back bonds are broken. The evaluated activation energy of the desorption of SiF4 is 0.8 eV. 
1996 International Conference on Solid State Devices and Materials (SSDM 96) 
YOKOHAMA, JAPAN