Combined transmission electron microscopy and x-ray study of the microstructure and texture in sputtered Mo films

Abstract

The microstructure and texture of thin Mo films sputtered onto the native oxide of Si(100) wafers were investigated with both conventional reflection x-ray pole figures, and transmission electron microscopy and diffraction. Films were grown at two deposition rates (powers), 34 nm/min (1.5 kW) and 67 nm/min (3.9 kW), onto both moving and stationary substrates, under otherwise identical experimental conditions. The microstructure of the Mo films evolved into a zone 2 microstructure within the first 2 μm of growth. The development of both out-of-plane and in-plane textures was found to be influenced by deposition rate and geometry. Films grown at the lower deposition rate exhibited predominantly {110} textures, while films grown at the higher rate exhibited predominantly {110} textures up to a film thickness of ∼0.5 μm and {111} textures above a film thickness of ∼1 μm. Films with the {110} textures developed grains with elongated footprints and faceted surfaces, while films with the {111} textures developed grains with elongated triangular footprints and faceted surfaces. In all of the films deposited onto moving substrates, an alignment of the grains normal to the tangent plane (defined by the substrate normal and the direction of platen rotation) was observed. In all of the films deposited onto stationary substrates, the development of an in-plane texture was suppressed. These results suggest that a combination of geometric, energetic, and kinetic mechanisms are contributing to the evolution of the microstructure and texture in the Mo films.