STUDY ON INHERENT STRESS OF VAPORIZED Ag FILM ON THE LASER REFLECTING MIRROR

激光反射镜上的银膜是由离子镀或气相沉积等PVD方法制备的。用X射线衍射法测量了玻璃上这两种类型的银膜的应力，发现离子镀膜具有不同于气相沉积膜的优先晶体生长取向，后者具有随机的晶体生长取向。然后，本研究以气相沉积的银膜为研究对象，通过实验和/或分析的方法对薄膜的残余应力进行了评价。利用X射线衍射法对两种类型的银气相沉积薄膜的残余应力进行了测量。一种是以氯化钠为衬底的银膜。在这种情况下，薄膜的残余压缩应力小于-70 Mpa。第二类是分离后不含氯化钠基片的银膜。分离出的银膜表面的残余应力小于-lt；正负&gt；20 Mpa，当膜厚小于2.0um时，残余应力几乎为零。同样，薄膜背面(衬底一侧)的残余应力约为-lt；正负&gt；15 Mpa，当薄膜厚度小于2.0um时，残余应力几乎为零。由这些测量结果可以清楚地看出，在薄膜/衬底界面的2.0微米深度内存在一些硬化层，例如固有应变。因此，可以用基于弹性理论的“梁理论”和“内应力理论”相结合的方法来估算银气相沉积薄膜的残余应力，并提出了估算公式。

Ag film on the LASER reflecting mirror is made by PVD such as ion plating or vapor deposition. Measuring the stresses in these two types of Ag films on the glass by X-ray diffracting method, it is appeared that ion plating film has a prioriyt of crystal growth orientation different from vapor deposited film which has random orientation of crystal growth. Then in this study, attention was paid on the vapor deposited Ag films to evaluate the residual stresses by experiments and/or analyzes. Using X-ray diffraction method, residual stresses of two types of Ag vapor deposited films were measured. The one type was Ag film with NaCl substrate. In this case, compressive residual stress less than -70MPa was obtained on the film. The second type, was Ag film without NaCl substrate after separating to each other. The residual stress on the surface of this separated Ag film was less than <plus-minus>20MPa and was almost zero when thickness of film was less than 2.0mum. Similarly, the residual stress on the back surface (substrate side) was about <plus-minus>15MPa and was almost zero when thickness of film was less than 2.0mum. By these measuring results, it became clear that there was some hardened layr within 2.0mum in depth from film/substrate interface such as an inherent strain. Consequently, the residual stresses on the Ag vapor deposited films can be evaluated by compound method of "beam theory" and "inherent stress theory" based on elasticity and its equation for estimation was newly propo