HfO_2/SiO_2薄膜的激光预处理作用研究

Laser conditioning effect of HfO_2/SiO_2 film

对电子束蒸发方式镀制的HfO2/SiO2反射膜采用大口径激光进行辐照,采用激光量热计测量了激光辐射前后的弱吸收值。实验发现HfO2/SiO2反射膜在分别采用1 064nm和532nm的激光辐照前后薄膜吸收分别从5.4%和1.7%降低到1.4和1.2%。采用聚焦离子束技术分析了激光辐照后薄膜的损伤形态并探究了损伤原因,发现:薄膜在激光辐照下存在节瘤的地方容易出现薄膜损伤,具体表现为熔融、部分喷发、完全脱落3种形态,节瘤缺陷种子来源的差异是导致其损伤机理也存在着巨大差异的主要原因。同时这些节瘤缺陷种子来源也影响着激光预处理作用效果,激光预处理技术对于祛除位于基底上种子形成的节瘤是有效的,原因是激光辐射过后该节瘤进行了预喷发而不会对后续激光产生影响;而激光预处理技术对位于膜层中间的可能是镀膜过程中材料飞溅引起的缺陷是无效的,需要通过飞秒激光手段对该类节瘤进行祛除。

Large aperture laser was used to irradiated the HfO2/SiO2 reflectors,which were evaporated from hafnia and silica by e-beam.Laser calorimeter was used to test the film absorption before and after laser irradiation.The results show that film absorption decreased from5.4%,1.7%to 1.4%,1.2%,when the measurement wavelengths were 1 064 and 532nm,respectively.Focused ion beam(FIB)was used to study the damage morphology after laser irradiation and to explore the cause of damage.The film where nodule existed was easily damaged,and the damage morphology mainly presented melt,partly erupted and absolutely fallen off.For the HfO2/SiO2 reflectors,laser conditioning was effective to eject the nodules on substrate.It was result from the nodule residue not to affect the subsequent laser.In addition,laser conditioning was not effective to the nodule in the film,which may be from the material spatter in coating process.In this case,other method can be used to get rid of the nodules.