Synchrotron radiation (SR) irradiation of amorphous SiO2 (a-SiO2) induces continuous removal of the SiO2 film without the use of etching gas. The dependence of the photostimulated evaporation rate on substrate temperature and SR intensity was measured and the reaction mechanism is discussed in detail separately for surface and bulk. Using the high material selectivity of the Sr-stimulated evaporation, a sefl-aligned process to fabricate a 0.6 µm line-and-space pattern is presented. Si surface cleaning is demonstrated as an example of application of this reaction to thin native oxide film grown by wet pretreatment. Si(100)-21 and Si(111)-77 structures were observed by reflection high energy electron diffraction (RHEED) at temperatures as low as 650. The difference between a-SiO2 and native oxide on the evaporation rate is higlighted. Epitaxial Si growth using disilane (Si2H6) gas occurs selectively in the SR-irradiated region on a Si(100) surface. Using SR irradiation in an ultrahigh vacuum, followed by residual oxide reduction by disilane, is proposed as an effective cleaning method.