CORRELATION BETWEEN DEFECT STRUCTURE AND ELECTRICAL-PROPERTIES OF DEFORMED SI SURFACES

Deformation by bending of Si wafers with left bracket 112 right bracket , left bracket 111 right bracket , and left bracket 100 right bracket surface orientation was produced by sputtering tantalum films on clean Si and on Si surface with a thermally grown oxide. Deposition of 0. 5-1- mu m Ta films produced radii of curvature in the Si wafers of from 350 to 50 m, respectively, as measured by the ABAC method. Stress on the Si surface as a function of annealing temperature exhibited a maximum of 400 degree C of 500 g/mm**2 and 650 g/mm**2 with and without oxide layer. Stress on tantalum films at 400 degree C was found to be 276. 3 kg/mm**2. At 300 degree C, stress on Ta film increased with Ta film thickness from 70 to 150 kg/mm**2. Transverse and sectional x-ray topographs have revealed small dislocation loops at the deformed Si surface. Defect structure produced by bending was correlated with the electrical measurements on the Si MOS configuration with thin and thick oxide, using conductance and capacitance methods. The effects of induced defects were studied by measuring the density and energy distribution of the surface states, surface potential, and flat band voltage. I-V characteristics of the oxide film indicated Ta diffusion through SiO//2 to the Si surface.