热处理对双离子束溅射SiO2薄膜力学及热力学特性的影响

光学薄膜的力学及热力学特性决定了光学系统性能的优劣。采用双离子束溅射的方法在硅110和肖特石英Q1基底上制备了SiO2薄膜，并对制备的膜层进行退火处理。系统研究了热处理前后SiO2薄膜的力学及热力学特性。研究结果表明，750℃退火条件下SiO2薄膜的弹性模量（Er）增加到72 GPa，膜层硬度增加到10 GPa。镀完后未经退火处理的SiO2薄膜表现为压应力，但是应力值在退火温度达到450℃以上时急剧降低，说明热处理有助于改善SiO2薄膜内应力。经退火处理的SiO2薄膜泊松比（vf）为0.18左右。退火前后SiO2薄膜的杨氏模量（Ef）都要比石英块体材料大，并且750℃退火膜层杨氏模量增加了50 GPa以上。550℃退火的SiO2薄膜热膨胀系数（f）从6.7810-7℃-1降到最小值5.2210-7℃-1。

Influence of thermal annealing on mechanical and thermoelastic characteristics of SiO2 films produced by DIBS

Mechanical and thermoelastic charecteristics of optical films are important to ensure the performance of optical coating systems. SiO2 films were prepared by dual ion beam sputtering (DIBS) on Si 110 and Schott Q1. The mechanical and thermoelastic properties of films as-deposited and annealed were systematically investigated. The results show that reduced Young's modulus (Er) is elevated to 72 GPa while the film was annealed at 750℃, and hardness (H) increases to over 10 GPa. The as-deposited films show compressive stress and the stress could be dramatically released while annealed over 450℃, incicating that heat treatment could improve the internal stress of SiO2 film. Poisson's ratio (vf) of annealed SiO2 films is around 0.18, and Young's modulus (Ef) of as-deposited and annealed films is larger than that of fused silica, and elevated over 50 GPa while annealed at 750℃. Thermal expansion coefficient (f) decreases from 6.7810-7℃-1 to the minimum value 5.2210-7℃-1 while annealed at 550℃.