一种射频MEMS开关高平整度牺牲层的制备方法

Method for Preparing High-Level Flatness Sacrificial Layer of Radio Frequency MEMS Switch

牺牲层工艺是制作MEMS开关的重要工艺,牺牲层平整度差会导致开关上电极变形,进而影响MEMS开关的性能.提出了一种高平整度聚酰亚胺牺牲层的制备方法,采用了自然平流法与双层牺牲层结合的方式.首先研究了温度对聚酰亚胺流动速度的影响,极大地缩短了自然平流法所需要的时间.自然平流法的局限性在于无法彻底解决聚酰亚胺牺牲层平坦度差的问题,之后可采用AZ5214光刻胶作为第二层牺牲层,进一步提高了牺牲层的平整度.固化后的聚酰亚胺性质稳定,不与酸碱反应,为光刻胶作为第二层牺牲层提供了条件.

The sacrificial layer process was an important process for fabricating MEMS switches.The poor flatness of the sacrificial layer caused deformation of the upper electrode of the switch,which in turn affected the performance of the MEMS switch.In this paper,a preparation method of a high flatness polyimide sacrificial layer was proposed,which adopted a natural flow method combined with a double-layer sacrificial layer.Firstly,the influence of temperature on the flow velocity of polyimide was studied,which greatly shortened the time required for the natural flow method.The limitation of the natural flow method was that the problem of poor flatness of the polyimide sacrificial layer cannot be completely solved.Then,AZ5214 photoresist can be used as the second sacrificial layer to further improve the flatness of the sacrificial layer.The cured polyimide is stable in nature and does not react with acids and bases,providing conditions for the photoresist to serve as a second sacrificial layer.