用于微反射镜制作的叠层光刻胶牺牲层工艺及残余应力控制

对应用于微反射镜制作的叠层光刻胶牺牲层工艺及微反射镜表面残余应力控制进行了研究。讨论了光刻胶牺牲层在电镀时的污染问题，提出电镀结束后重新制作光刻胶牺牲层的方法来保证牺牲层表面质量。同时提出蒸发-电镀相结合的工艺解决了上层光刻胶溶剂穿过中间结构层浸入底层光刻胶的问题，并通过控制蒸发与电镀过程中应力状态不同的两层金属薄膜的厚度解决了微反射镜镜面存在残余应力问题。最后成功释放了长620μm、宽500μm、厚2μm、悬空高为12μm的微反射镜结构。

Research of Laminated Photoresist Sacrificial Layer Technology and Residual Stress in Micromirror Fabrication

The laminated photoresist sacrificial layer technology and residual stress control in micromirror fabrication were investigated.Pollution problems in electroplating related to the photoresist sacrificial layer were discussed and their solutions were proposed.Through experiments,a new fabrication process is developed to solve the problem that the solvent in upper photoresist penetrates the electroplating base metal layers and dissolves the sacrificial layer to damage middle layer;the thicknesses of two kinds of metal films with different stress states in evaporating and electroplating processes are controlled to remove the residual stress on the surface of a micromirror.Employing these new technologies,the perfect flat micromirror with the size of 620 μm×500 μm×2 μm,and air gap height of 12 μm is fabricated successfully.