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

激光反射镜上的Ag膜是通过诸如离子镀或气相沉积的PVD制成的。用X射线衍射法测定了玻璃上两种Ag膜的应力，发现离子镀膜具有优先的晶体生长取向，而气相沉积膜具有随机的晶体生长取向。然后，在这项研究中，注意力集中在气相沉积的银膜，以评估残余应力的实验和/或分析。用X射线衍射法测量了两种Ag气相沉积膜的残余应力。一类是以NaCl为衬底的Ag膜。在这种情况下，在膜上获得小于-70MPa的压缩残余应力。第二类是分离后的无NaCl基底的Ag膜。该分离的Ag膜的表面上的残余应力小于<plus-minus>20 MPa，并且当膜的厚度小于2.0 μ m时，残余应力几乎为零。类似地，背面（基板侧）上的残余应力为约<plus-minus>15 MPa，并且当膜厚度小于2.0 μ m时几乎为零。通过这些测量结果，可以清楚地看出，在距离膜/基底界面2.0 μ m的深度内存在一些硬化层，例如固有应变。因此，可以用基于弹性力学的“梁理论”和“内应力理论”的复合方法来计算Ag气相沉积膜的残余应力，并提出了新的残余应力计算公式。

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