Preparation of silicon oxide films having a water-repellent layer by multiple-step microwave plasma-enhanced chemical vapor deposition

Preparation of silicon oxide films having a water-repellent surface has been succeeded by means of a multiple-step microwave plasma-enhanced chemical vapor deposition (PECVD) process. The maximum water repellency of 110 degrees was attained. In the first step of coating, a silicon oxide layer was prepared using a mixture of an organosilicon compound, that is, tetramethylsilane or tetramethoxysilane, and oxygen as a source gas. In the second step, oxygen was replaced with FAS-17 [(heptadecafluoro-1,1,2,2-tetrahydro-decyl)-1-trimethoxysilane]. We started to introduce FAS-17 using Ar carrier gas into the reactor and to reduce gradually supplying oxygen. Final step, in the absence of oxygen supply, the surface was further treated in the plasma for 1-10 min after the partial pressure of TMS or TMOS was adjusted so as to be equal to that of FAS-17/Ar. The films prepared by this process had high water repellency, hardness and transparency. The adhesion between the silicon oxide and the water-repellent layers was good due to the existence of the middle layer which consisted of inorganic and organic compositions. (C) 1998 Elsevier Science S.A. All rights reserved.