Preparation of Al-doped ZnO sputter target by hot pressing
(General Research Institute for Nonferrous Metals, Beijing 100088, China)
Abstract: Al-doped ZnO (AZO) target was prepared by hot pressing using ZnO and Al2O3 powder in mass ratio of 98:2. The effects of hot pressing conditions including temperature, pressure and preserving time on relative density were investigated. Pore evolution and phase structure change during densification process were studied. The results show that AZO target with super high relative density of 99% was prepared by two-stage hot pressing method under pressure of 35 MPa, temperature of 1 050 °C and 1 150 °C with preserving time of 1 h, respectively. At temperature around 1 050 °C, the number of isolated pore was minimum. At temperature lower than 900 °C, there existed Al2O3 phase. At temperature higher than 1 000 °C, ZnAl2O4 phase was generated and its content was increased with temperature increasing. Hot pressing method had the advantage over pressureless sintering that the content of ZnAl2O4 was lower and sintering temperature could be also lower. With increasing the hot pressing temperature and preserving time, the electric resistivity of AZO target decreased greatly. A low resistivity of 3´10−3 W×cm was achieved under the temperature of 1 100 °C, pressure of 35 MPa and preserving time of 10 h.
Key words: aluminum-doped ZnO (AZO); sputter target; hot pressing; pore; phase structure