Fiber texture of sputter deposited molybdenum films and structural zone model

• Ultra thin (2.5 nm) to thin film (100 nm) of Mo was studied.
• Texture evolution was studied by TEM diffraction patterns with tilting film.
• Fiber texture was observed for ultra thin film at initial growth stage.
• Zone II growth mechanism was proposed without intentional substrate heating.

The texture orientation of 2.5, 5, and 100 nm thick Mo films grown by sputter deposition on SiO2 membranes at room temperature has been studied quantitatively using transmission electron microscopy. The sample tilt angle dependent diffraction patterns of these films revealed a fiber texture with the [110] out-of-plane direction for all film thicknesses. Films grown at different sputtering power and substrate–target distance showed a similar texture orientation. These results would imply that the growth was in zone II, according to the microstructure classification of the structural zone model. This is in contrast to the conventional assignment of zone I for Mo deposition at room temperature based on the low Mo homologous temperature of ∼0.1. It was found that texture dispersion was reduced as the thickness of the film increased. Possible mechanisms, including energetic particles bombardment during growth, which could affect the surface mobility and texture of the films, were discussed.