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6649503 
Journal Article 
MECHANISMS OF THE HF/H2O VAPOR-PHASE ETCHING OF SIO2 
Helms, CR; Deal, BE; , 
1992 
AMER INST PHYSICS 
WOODBURY 
806-811 
WOS:A1992JE68100044 
In this paper we report on studies of the mechanisms responsible for HF/H2O etching and cleaning of Si surfaces. From these studies we have clearly established that the role of water is to provide a condensed solvent medium for the HF on the surface. Our results, as well as those in the literature, show that if the partial pressures of HF and H2O are too low (or sample temperature too high) condensation does not occur and little or no oxide etching is observed. Based on these ideas and vapor pressure data from the literature, we have developed a detailed model that provides for the calculation of the onset of condensation as a function of wafer temperature and reactant partial pressures. In addition, the model allows determination of the HF concentration in the condensed H2O film. Comparison of etch rates obtained for aqueous etching as a function of HF concentration and vapor phase etching as a function of calculated HF concentration show good agreement. 
38TH NATIONAL SYMP OF THE AMERICAN VACUUM SOC 
SEATTLE, WA