Study On Testing Method For Surface Profiling Of MEMS' Devices With Trench Structure

Optical interference microscopy is a typical technique for obtaining surface morphology and is extensively applied for the semiconductor devices, the optical processing, MEMS (Micro Electronic Mechanical System) technology and micro-and nano- materials analysis. With the development of MEMS, interference technology has become a kind of suitable method, especially in the high aspect ratio micro-structure processing testing, for online and non-destructive testing for processing of MEMS devices. Generally, the width of high aspect ratio micro-structure is about 1～10μm ,height is 10～500μm , the deep aspect ratio is between 10:1 and 100:1. The existing equipments can only test the MEMS device's structures under the condition of broken devices and can not satisfied for the requirements of online and non-destructive testing. Therefore, it is very important to develop a technique of online and non-destructive testing for MEMS'devices with trench structure.Focusing on online and non-destructive testing for MEMS'devices with trench structure, infrared interference technology is put forward based on the transmission characteristic of semiconduct materials in infrared band. The infrared interference testing system is established and the testing method is verified via related experiments.The main works in this thesis are listed as follows:(1) A new scheme for the online and non-destructive testing of processing of MEMS devices is introduced based on the optical properties of semiconductor materials. silicon semiconduct materials(Si,GaAs) is transparent in the infrared band ( the infrared wavelength is above 1.1μm). The surface profiling of MEMS'devices with trench structure can be measured by utilizing the infrared interference technology.(2) According to the infrared interference testing method , the key components (infrared light source and InGaAs detector) are selected. The affect factors of interence stripe are analysed. The infrared interference testing system is established with optical interference microscopy, PZT controling system and operation software.(3).The infrared interference testing system is evaluated by using the silicon-glass bonding samples. The transmission phenomenon of the silicon-glass bonding samples is observed through the testing system. The transmission interference stripes are obtained and the three-dismension morphology of samples are measured. In order to improving testing precision of the system.the result prove the innovation method for testing the surface profiling of MEMS'devices with the trench structure. the mathematic compensation model for the varying the difference of optical path lengths is put forward.