PREFERRED ORIENTATION OF TIN FILMS STUDIED BY A REAL-TIME SYNCHROTRONX-RAY-SCATTERING

The orientational crossover phenomena in a radio frequency (rf) sputte ring growth of TiN films were studied in in situ, real time synchrotro n x-rap scattering experiments, For the films grown with pure Ar sputt ering gas, the crossover from the (002)-oriented grains to the (111)-o riented grains occurred as the film thickness was increased. As the sp uttering power was increased, the crossover thickness, at which the gr owth orientation changes from the [002] to the [111] direction, seemed to decrease. The addition of N-2 besides Ar as sputtering gas suppres sed the crossover, and consequently resulted in the (002) preferred or ientation without exhibiting the crossover. We attribute the observed crossover phenomena to the competition between the surface and the str ain energy. The x-ray powder diffraction, the x-ray reflectivity, and the ex situ atomic force microscopy surface topology studies consisten tly suggest that the microscopic growth front was in fact always the ( 002) planes. In the initial stage of growth, the (002) planes were ali gned to the substrate surface to minimize the surface energy. At later stages, however, the (002) growth front tilted away from the surface by about 60 degrees to relax the strain, which caused the crossover of the preferred growth direction to the [111] direction. (C) 1997 Ameri can Institute of Physics.