濺鍍法中以空氣為基底製備Zr-N-O薄膜之製程區間與特性研究

Abstract

This study focues on the characterization and processing window of ZrN, ZrNxOy, Zr2ON2 and N-doped ZrO2 thin films prepared with various sputter power, air/Ar flow ratio, substrate temperature by using air as a reactive gas in sputtering. This process replaces conventional process that uses nitrogen and/or oxygen as reactive gases to prepare above-mentioned films, which is conducted at low vacuum and reduces drastically the processing time and process cost. The deposition parameters were sputter power (100~400 W), air/Ar flow ratio (0~1.0) and substrate temperature (25~600°C). Other deposition parameters including base pressure (1.3x10-2 Pa), substrate bias (-50 V), and sputter time (20 min) were fixed throughout the study. The influences of parameters on the crystalline phase, microstructure, resisivity, residual stress, chemical composition and optical bandgap were investigated. When substrate was not heated, at low sputter power (100 W) the processing window of ZrN was narrow and quickly transformed to Zr2ON2, N-doped ZrO2 with increasing air/Ar flow ratio. At high sputter power (400 W) there existed a broad processing window, compared to low sputter power. Thermodynamics is primarily dominant in the oxide region in plasma, and kinetics was obvious dominant under the conditions of higher sputter power and lower air/Ar flow ratio from the three-dimensional processing window of sputter power, air/Ar flow ratio and substrate temperature. When increasing the air/Ar flow ratio, substrate temperture played a role on thermodynamics to induce oxidation. In preparing ZrN thin films, the resistivity of ZrN films was lower by controlling suitable air/Ar flow ratio, higher sputter power and substrate temperature. The range was 96±3~289±20 μΩ-cm. Before applying the sububstrate temperature, the resistivity was 121±3 μΩ-cm at sputter power of 400 W, air/Ar flow ratio 0.2, which reached the lowest value of 96±4 μΩ-cm at the substrate temperature 600°C. In preparing Zr2ON2, N-doped ZrO2 thin films, the structure of thin films tranformed Zr2ON2 to N-doped ZrO2 and the nitrogen content decreased with increasing air/Ar flow ratio 0.3 to 1.0. The optical bandgap of thin films increased from 2.23 eV to 4.51 eV. When the substrate temperature increasesed from 25°C to 600°C, the optical bandgap of Zr2ON2 had no tendency with increasing substrate temperature at the sputter power of 400 W and air/Ar flow ratio 0.3. The optial bandgap was in the range of 1.79~2.59 eV. The optical bandgap of N-doped ZrO2 slightly decreased from 4.51 eV to 4.39 eV by increasing substrate temperature at the sputter power of 400 W and air/Ar flow ratio 1.0. This films was in the range of 1.79~4.51 eV, included visible to UV (690~280 nm) and had a broad optical bandgap.