Observation of the adhesion of thin Ta polycrystalline films to Si wafers via in situ topography/radiography

The adhesion of thin polycrystalline metallic Ta films to Si wafer substrat es was studied in situ under real-time conditions using white-beam synchrot ron Laue transmission diffraction topography with simultaneous radiographic imaging. The observations were carried out using a newly developed experim ental apparatus, which consisted of a computer-controlled mini-tensile stag e, an 800 degrees C ancillary furnace, and a CCD X-ray imaging system. The stress and imaging data were collected simultaneously via a video recorder and also at selected intervals by frame-grabbing/storage technology on a mi crocomputer. This allowed direct correlation between the stress, temperatur e and film-failure processes. The results for sputtered Ta polycrystalline thin films deposited onto Si wafers indicated that induced stresses led to buckling delaminations along well-defined directions. These observations ca n be readily extended to study a variety of film-adhesion and cycle-failure problems.