QUANTITATIVE ACOUSTIC MICROSCOPY FOR CHARACTERIZATION OF THE INTERFACE STRENGTH OF DIAMOND-LIKE CARBON THIN-FILMS

Diamond-like carbon (DLC) films are emerging to be ideal materials in a variety of semiconductor, display, and film media applications. As w ith any deposited film, adhesion of the film to the substrate is of cr itical importance. The main objective of this paper is to report on th e development of a technique based on acoustic microscopy for the quan titative characterization of the interface strength of thin (submicrom eter) films. Preliminary results from 0.5 mu m DLC films are presented to establish the feasibility of the new technique. Theoretical models of wave propagation indicate the Rayleigh wave velocity (at 600 MHz) is sensitive to the interface condition and could potentially be used to characterize the same. Acoustic material signatures (AMS) of DLC fi lms which had varying levels of adhesion to silicon coated titanium su bstrates were obtained at 600 MHz using an acoustic microscope. The Ra yleigh velocity (extracted from the AIMS) had a strong correlation wit h the adhesion strength measured destructively using a pull tester. A model-based methodology for prediction of the interface strength of th in films through acoustic microscopy is also addressed. (C) 1997 Publi shed by Elsevier Science S.A.