Thermal Stress Behavior of Aluminum Nanofilms under Heat Cycling

In-situ thermal stress in aluminum nanofilms with silicon oxide glass (SOG) passivation was investigated by using synchrotron radiation at the SPring-8. Aluminum films of varying thickness (10, 20, 50 nm) were deposited on thermally oxidized silicon wafers by RF magnetron sputtering. Each specimen was heated in air over two cycles between room temperature and 300 deg. C. The following results were obtained: (1) {111} planes of aluminum nanofilm crystals were oriented parallel to the substrate normal; (2) the intensity of 111 diffraction was almost independent of temperature except in the case of the 50-nm-thick film; (3) the FWHM of 111 diffraction was almost independent of temperature at any given film thickness; and (4) for all films, the thermal stress varied linearly with heating temperature, and the hysteresis between the heating and cooling steps disappeared