The processes of capacitive MEMS accelerometers generally use: surface process, bulk silicon process, LIGA process and SOI + DRIE process, etc.
Surface technology is a micro-technology developed on the basis of integrated circuit planar technology, and only performs single-sided lithography. It uses the sequential deposition and selective etching of different materials on the silicon plane to form various microstructures. It mainly includes sacrificial layer deposition, sacrificial layer etching, structural layer deposition, structural layer etching, sacrificial layer removal (release structure), etc. Finally, the structural material is suspended above the substrate to form a two-dimensional or three-dimensional structure of various shapes.
The bulk silicon process refers to a process of etching a silicon substrate along the thickness direction of the silicon substrate, including wet etching and dry etching, and is an important method for realizing a three-dimensional structure. In order to form a complete microstructure, bonding or bonding technology is often used on the basis of processing, combining silicon bonding technology with bulk silicon processing methods. The microstructure of silicon is formed through multiple masking, single-sided or double-sided lithography and anisotropic etching, and then the relevant parts are precisely aligned and bonded into a whole. The bulk silicon processing technology process is more complicated than silicon surface processing, large in size and high in cost.
The SO1 + DRIE process is an extension and development of the bulk silicon process. The use of silicon-on-insulator (SOI) to fabricate single-crystal silicon three-dimensional microstructures has been an extremely rapid method in recent years. Almost all methods of manufacturing microstructures using SOI use DINE (deep reactive ion etching) to deeply etch single crystal silicon. Depending on the structure, performance requirements, etc., the front structure release and the back structure release can be used.
If you want to get more details about MEMS accelerometer,pls visit https://www.ericcointernational.com/gyroscope/mems-gyroscope/