EVALUATION OF ADHESION STRENGTH OF TI FILMS ON SI(100) BY THE INTERNAL-STRESS METHOD

Titanium films were sputter deposited onto Si(100) surface. Adhesion s trength of the Ti film was evaluated by the internal stress method. Th e Ti film was overcoated by a Ni coating in the state of a high intern al stress, the value of which was about 0.5 GPa(tensile). The internal stress induces large normal and shear stress at the interface between the Ti film and the Si(100) surface. Those stresses increase with the increase of the Ni coating thickness. The stress distribution was eva luated by the finite element method. The evaluation shows that the nor mal stress on the interface is extremely large at the edge of the samp le. This result suggests that a peeling of the Ti film is initiated at the edge and is consistent with observed spontaneous peeling phenomen a. We could determine the adhesion strength of the Ti film by measurin g the thickness of the Ni coating to peel off the Ti film. The value w as found to range in 0.1-1 GPa region. The effect of the Ar ion bombar dment of Si substrate on the adhesion enhancement was investigated in detail by this method. (C) 1998 Elsevier Science S.A.