低温退火的X射线W/Si多层膜应力和结构性能  

Stress and structure properties of X-ray W/Si multilayer under low temperature annealing

作　　者：张金帅[1] 黄秋实[1] 蒋励[1] 齐润泽 杨洋[1] 王风丽[1] 张众[1] 王占山[1] 

机构地区：[1]同济大学精密光学工程技术研究所,同济大学物理科学与工程学院,先进微结构材料教育部重点实验室,上海200092

出　　处：《物理学报》2016年第8期281-287,共7页Acta Physica Sinica

基　　金：中国科学院战略性先导科技专项(批准号:XDA04060605);国家重大科学仪器设备开发专项(批准号:2012YQ24026402)资助的课题~~

摘　　要：W/Si多层膜反射镜在硬X射线天文望远镜中有重要应用.为减小其应力对反射镜面形和望远镜分辨率的影响,同时保证较高的反射率,采用150,175和200°C的低温退火工艺对采用磁控溅射镀制的W/Si周期多层膜进行后处理.利用掠入射X射线反射测试和样品表面面形测试对退火前后W/Si多层膜的应力和结构进行表征.结果表明,在150°C退火3 h后,多层膜1级峰反射率和膜层结构几乎没有发生变化,应力减少约27%;在175°C退火3 h后,多层膜膜层结构开始发生变化,应力减少约50%;在200°C退火3 h后,多层膜应力减小超过60%,但1级布拉格峰反射率相对下降17%,且膜层结构发生了较大变化.W,Si界面层的增大和相互扩散加剧是应力和反射率下降的主要原因.The X-ray timing and polarization telescope proposed in China is for imaging spectroscopy in an energy range of1–30 ke V. To obtain the high energy spectrum response with a large effective area, W/Si multilayer mirrors each with a mirror thickness of only 0.3 mm are used. This makes the figure accuracy of the mirror and the distortion caused by the multilayer stress an important issue during the telescope development. W/Si multilayer mirror is an important component of X-ray telescope for astronomical observation. To reduce the effect of the multilayer stress and maintain a high reflectivity at the same time, the W/Si multilayers prepared by magnetron sputtering deposition are annealed at low temperatures of 150℃, 175℃ and 200℃, respectively, for 3 h. The stress of the multilayer is determined based on the surface figure measurements of each sample before and after annealing. The X-ray reflectance and layer structure of the multilayer are characterized by the grazing incidence X-ray reflectometry（GIXR） and the reflectance fitting curves. The first Bragg peak reflectivity of the as-deposited sample is 67% at 8.04 ke V and the multilayer stress is around-260 MPa.After annealing at 150℃ for 3 h, the first Bragg peak reflectivity and the layer structure are almost the same as before annealing, while the stress reduces 27%. The fitting results display almost the same interface widths of the multilayer before and after annealing. As the temperature increases to 175℃, the first Bragg peak reflectivity drops by about2%. The multilayer structure begins to deteriorate and the W/Si interface widths increase from 0.346 nm/0.351 nm to0.356 nm/0.389 nm, according to the fitting results, while the stress reduces about 50%. After annealing at 200？C for3 h, the stress reduces 60% and the stress decreases down to about-86 MPa. However, the first Bragg peak reflectivity drops by 17%, and the layer structure undergoes significant change after annealing. The W/Si interface widths increase from 0.352 nm/0.364 nm to 0

关 键 词：X射线 W/Si多层膜 退火 应力 

分 类 号：TH751[机械工程—仪器科学与技术] O434.1[机械工程—精密仪器及机械]