Microstructure and magnetron sputtering properties of tungsten target fabricated by low pressure plasma spraying

Abstract

Planar and rotary tungsten targets were fabricated by low pressure plasma spraying (LPPS). Relative density, oxygen content by mass, microstructure, micro-hardness and ultimate tensile strength (UTS) of LPPS tungsten targets were all influenced by vacuum pressure. Compared with 1.3 × 104 Pa and 6.5 × 104 Pa, a vacuum pressure of 3.9 × 104 Pa was optimal for preparing high-quality tungsten targets. Oxygen content by mass, porosity, average grain size, micro-hardness and UTS of LPPS target fabricated under 3.9 × 104 Pa were about 0.18%, 2.8%, 0.9 μm, 377.8HV0.025 and 201.1 MPa, respectively. Electron backscattered diffraction (EBSD) from the LPPS sample (fabricated under 3.9 × 104 Pa) showed that proportions of 〈001〉, 〈011〉 and 〈111〉 oriented grains were 10.6%, 21.0% and 12.3% of the total, respectively. The tungsten target possessed excellent magnetron sputtering performance since most tungsten grains with a size <1.0 μm were irregularly distributed without preferred orientation. Rapid sputtering and uniform thinning on the surface of LPPS tungsten targets took place with nano-scaled sputtering pits being formed during magnetron sputtering. Smooth and continuous tungsten thin films with thickness about 320 nm can be deposited by magnetron sputtering from the LPPS samples. XRD spectra of tungsten thin films with body centered cubic structure showed that the intensity of the (110) diffraction peak was much higher than those of the (200), (211) and (220) peaks.