Abstract
Film structure is widely utilized in various products from electronic parts to daily necessaries. Evaluation of adhesion of thin film is therefore an important issue. In this paper, the applicability of scratch test to the evaluation of adhesion of thin film is discussed.
Al and Cu were vacuum evaporated on glass substrates. Those specimens were subjected to scratch test in which a diamond stylus scratches film on the substrate and the resultant scratch patterns were observed by SEM and optical microscope.
Scratch patterns were classified into four categories ; 1) uniformly thinned track, 2) uniformly film detached track, 3) irregularly film detached track and 4) intermediate shape of those three. Most of the scratch patterns of Al film were classified into category-1. On the other hand, those of Cu film were varying from category-1 to category-4. Category-2 corresponds the clear-track which was defined by Benjamin et. al., and shear strength of film adhesion can be calculated correctly in this case. It should be noted that category-1 and category-2 cannot be distinguished each other by the optical inspection alone, it requires careful inspection including composite analysis by SEM.
