MUMPS工艺概况
The MUMPS process is a three-layer polysilicon surface micromachining process derived from work performed at the Berkeley Sensors and Actuators Center (BSAC) at the University of California. Several modifications and
enhancements have been made to increase the flexibility and versatility of the process for the multi-user environment. The process flow described below is designed to introduce inexperienced users to polysilicon micromachining. The text is supplemented by detailed drawings that show the process flow in the context of building a typical micromotor.
工艺流程详解
衬底： 100 mm n-type (100) silicon wafers of 1-2 ohm-cm resistivity.
低阻硅片
1. The surface of the wafers are first heavily doped with phosphorus in a standard diffusion furnace using POCl3 as the dopant source.
This helps to reduce or prevent charge feed through to the substrate from electrostatic devices on the surface.
2. 600 nm low-stress LPCVD (low pressure chemical vapor deposition) silicon nitride layer is deposited on the wafers as an electrical isolation layer.
3. deposition of a 500 nm LPCVD polysilicon film-Poly 0. 4. the coating of the wafers with photoresist
5. Exposure of the photoresist with the appropriate mask 6. Developing the exposed photoresist to create the desired etch mask for subsequent pattern
7. Transfer into the underlying layer －The Poly 0 layer is then etched in an RIE system
只刻蚀多晶硅而不刻蚀硅，需要细致选择刻蚀剂和刻蚀工艺 8. After etch, the photoresist is chemically stripped in a solvent bath.
9. A 2.0 μm phosphosilicate glass (PSG) sacrificial layer is then deposited by LPCVD
