不同退火过程对紫外HfO_2/SiO_2,Y_2O_3/SiO_2多层膜性能的影响

Effect of Annealing on HfO_2/SiO_2 ,Y_2O_2/SiO_2 Multilayer Thin Films

采用直升式和阶梯式加热法对电子束热蒸发镀制出的HfO2/SiO2,Y2O3/SiO2多层膜进行了400℃的退火处理,发现采用阶梯式加热法退火后多层膜在190～300 nm范围内的峰值反射率均得到提高,说明此种后处理方法可能会改善膜层在紫外波段的光学性能。再对HfO2,,2O3的单层膜进行行相应的退火处理,发现退火后HfO2膜层的物理厚度减小从而发生蓝移现象;直升式退火使Y2O3膜层的折射率变小引起蓝移,阶梯式退火使得Y2O3膜层的物理厚度减小引起蓝移。对退火前后样品的微结构进行X射线衍射(XRD)法测量发现,退火可以使材料进行晶化,并且采用直升式加热法后材料的结晶度更大,从而膜内散射变大,会引起膜层反射率的轻微降低。

HfO2/SiO2,Y2O3/SiO2 ultraviolet multilayer thin films were annealed in air at 400℃ through different models： temperature rising linearly or step by step. It was found that the peak reflectances of all samples raised at 190-300 nm if the temperature was rised step by step. Corresponding single-layer thin films were annealed through the two different ways, the physical thickness of HfO2 layer reduced. If the temperature rised linearly, the refractive index of YeO3 film reduced, which also resulting in blues shifting. If the temperature rised step by step, the wavelength would shift to shorter way because of the reduce of physical thickness. Microstructures of the films before and after annealing were characterized by X-ray diffraction （XRD） , it showed that annealing could crystallized the materials. If the temperature rising linearly, bigger crystals would cause more scattering, then reduce the reflectance of the film.