Stress, Roughness and Reflectivity Properties of Sputter-Deposited B4C Coatings for X-Ray Mirrors  

作　　者：Jia-Li Wu Run-Ze Qi Qiu-Shi Huang Yu-Fei Feng Zhan-Shan Wang Zi-Hua Xin 吴佳莉;齐润泽;黄秋实;冯宇飞;王占山;辛子华(Department of Physics,Shanghai University,Shanghai 200444;MOE Key Laboratory of Advanced Micro-Structured Materials,Shanghai 200092;Institute of Precision Optical Engineering,School of Physics Science and Engineering,Tongji University,Shanghai 200092)

机构地区：[1]Department of Physics,Shanghai University,Shanghai 200444 [2]MOE Key Laboratory of Advanced Micro-Structured Materials,Shanghai 200092 [3]Institute of Precision Optical Engineering,School of Physics Science and Engineering,Tongji University,Shanghai 200092

出　　处：《Chinese Physics Letters》2019年第12期17-21,共5页中国物理快报（英文版）

基　　金：Supported by the National Key R&D Program of China under Grant No 2016YFA0401304;the National Natural Science Foundation of China under Grant Nos 61621001,U1732268 and 11875203;the Shanghai Municipal Science and Technology Major Project under Grant No 2017SHZDZX02

摘　　要：Boron carbide(B4C)coatings have high reflectivity and are widely used as mirrors for free-electron lasers in the x-ray range.However,B4C coatings fabricated by direct-current magnetron sputtering show a strong compressive stress of about-3 GPa.By changing the argon gas pressure and nitrogen-argon gas mixing ratio,we are able to reduce the intrinsic stress to less than-1 GPa for a 50-nm-thick B4C coating.It is found that the stress in a coating deposited at 10 m Torr is-0.69 GPa,the rms roughness of the coating surface is 0.53 nm,and the coating reflectivity is 88%,which is lower than those of coatings produced at lower working pressures.When the working gas contains 8%nitrogen and 92%argon,the B4 C coating shows not only-1.19 GPa stress but also a low rms roughness of 0.16 nm,and the measured reflectivity is 93%at the wavelength of 0.154 nm.Boron carbide（B4C） coatings have high reflectivity and are widely used as mirrors for free-electron lasers in the x-ray range. However, B4C coatings fabricated by direct-current magnetron sputtering show a strong compressive stress of about-3 GPa. By changing the argon gas pressure and nitrogen-argon gas mixing ratio, we are able to reduce the intrinsic stress to less than-1 GPa for a 50-nm-thick B4C coating. It is found that the stress in a coating deposited at 10 m Torr is-0.69 GPa, the rms roughness of the coating surface is 0.53 nm, and the coating reflectivity is 88%, which is lower than those of coatings produced at lower working pressures. When the working gas contains 8% nitrogen and 92% argon, the B4 C coating shows not only-1.19 GPa stress but also a low rms roughness of 0.16 nm, and the measured reflectivity is 93% at the wavelength of 0.154 nm.

关 键 词：coating STRESS CARBIDE 

分 类 号：TG1[金属学及工艺—金属学]