We examined the structure around the interface of SiO2 and Si using medium-energy ion scattering spectroscopy (MEIS) to investigate the interfacial Si displacement of an ultrathin silicon dioxide formed by oxidation of a Si(100) substrate with atmospheric-pressure ozone at a substrate temperature of 375°C. A thermally grown oxide with the same thickness as an ozone-formed oxide was also measured with MEIS for comparison. The ozone-formed oxide exhibited considerably less Si displacement in the oxide layers near the interface than a thermally grown oxide, which indicates that an ozone oxide is homogenous. These results explain well our previous findings that an ozone oxide exhibits a constant HF etching rate of silicon dioxide while a thermally grown oxide slows the etching rate near the interface.
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