On The Formation Of Diffusion Layer Between Cr Film And Glass

Abstract

Chromium films are commonly used as a metal “glue” layer because of good adhesion to glass. It is believed that an intermediate oxide layer is formed during deposition, since Cr has a very strong affinity for oxygen. For example, a graded Cu/Cr/CrOx/SiO2structure ensures excellent adhesion of Cu to glass, whereas Cu exhibits poor adhesion to most dielectrics. In our recent study, however, a diffusion layer, Cr2O3+SiOy, was observed between CrOxand SiO2(glass) substrate. It is quite likely that this diffusion layer is responsible for the good adhesion of Cr film to glass.The relative compositions of the major components across the interface are shown in Fig 1. A Cr film was evaporated on Corning Code 1737 glass (Al2O3-B2O3-SiO2with ˜67at.% Si02) substrate at room temperature (RT) and subsequently covered with about lOnm Cu. A 5nm'wide diffusion layer is seen. The corresponding regions are also indicated in Fig 2, an Annular Dark Field (ADF) image whose contrast is approximately proportional to the density if the thickness is assumed uniform.