MEMS表面加工中材料层厚度电学测试结构

Electrical testing structure for measuring material layer thickness of MEMS surface processing

微机电系统(MEMS)表面加工工艺中的材料层厚度是决定MEMS器件性能的重要参数之一,如多晶硅结构层厚度和牺牲层厚度,直接决定了MEMS器件的机构性能和结构的纵向移动范围,因此对材料层厚度进行测试和工艺控制监视是极具意义的.当前的材料层厚度测试大多采用光机械的方法,因其测试方法复杂、设备昂贵、测试时间长且很难集成到一个工艺控制监视(PCM)系统中,提出一种新颖的材料层厚度电学测试结构,该测试结构具有结构简单、测量方便并且便于MEMS测试系统集成的特点.通过软件对测试结构和测试模型进行闭环验证,结果表明,模拟值与理论值有较好的一致性.

Material layer thickness of Micro-Electro-Mechanical System（ MEMS） surface manufacturing process is one of the significant parameters which determine the performance of MEMS devices,for example,the thickness of polysilicon layer and sacrificial layer directly determines the performance and longitudinal mobile range of MEMS devices,so the measurement and process control and monitoring of material layer thickness are very meaningful. The current material layer thickness test,which is mostly through optomechanical method,is too complex and expensive, and needs too much measuring time. Besides,it is difficult for the current method to integrate with the Process-con- trol-monitor（ PCM） system. In the paper,a novel electrical testing structure is developed to measure the material layer thickness,which is simple and convenient,and can be integrated with the MEMS measurement system easily. To validate the testing structures and testing models,the software Medici is used to carry out the closed-loop verifi- cation. The results show a good agreement between simulation results and theoretical results.