Various clean complicated micro-pattern designs based on n-octadecyltrichlorosilane (OTS) self-assembled monolayer (SAM) on silicon substrates have been realized in large area by using vacuum ultraviolet (VUV) light irradiation at the wavelength of 172 nm. The degradation process of the alkylsilane SAM with irradiation time evolution has been traced by using ellipsometry, water contact angle measurement and X-ray photoelectron spectroscopy (XPS) techniques in detail. The results indicate that the SAM can be completely removed in several minutes by the irradiation of the shorter wavelength vacuum ultraviolet light. Furthermore, the ability of the OTS-SAM as resist for chemical etching has also been demonstrated. (c) 2005 Elsevier B.V. All rights reserved.