The interfacial strengths of organosilicate glasses deposited on silicon wafer have been investigated. Three different testing methods, the microscratch test, four-point bending test, and the modified edge lift-off test, were used to determine the interfacial strengths between the inorganic C-doped organosilicate glass (OSG) and the silicon wafer. The results show that the adhesion energy decreases with increasing film thickness in the four-point bending and modified edge lift-off tests, but it increases as the thickness increases in the microscratch test. The difference in the trends is due to the different deformation modes operating in the testing processes. (C) 2007 Elsevier B.V. All rights reserved.