Preliminary Research On Micro Vacuum Sensor Based On Field Emission Of Silicon Tip

In this thesis,the MEMS vacuum sensor based on field emission of silicon tips array is brought forward firstly by integration of the MEMS technology and vacuum microelectronics technology at the situations of few researches and no usable product at present.This vacuum sensor fabricated by MEMS techniques utilizes the field emission phenomena as its sensing mechanism.It consists of cathode silicon tips array,brace and anode,and is characterized of high sensitivity,easiness for integration and mass production etc.This vacuum sensor has very promising market potential and wide applications,which can be applied in vacuum equipments,aerospace equipments, medical instruments etc.or any place where vacuum testing is required,especially used in reliability test by integrating into those vacuum packaged micro devices.The research mainly focuses on the following six aspects:(1) Bring forward a prototype of the MEMS vacuum sensor based on field emission of silicon tips array.(2) Design the vacuum sensor's structure and complete fabrication technique. The masks shapes and templates used for experiment are also designed based on the sensor's structure and fabrication technique.After analyzing the requirements and key points of sensor fabrication,the fabrication parameters were optimized by systematic experiments on sensor's fabrication processes, and get the sample sensor with silicon tip which diameter is 70nm(3) Study the fabrication process of the gated silicon tips array and get it with 3μm aperture by means of self-align technology,laying foundations for further researches on the field emission vacuum sensor.(4)Ⅰ-Ⅴcharacteristics of the sample under ordinary pressure condition were tested.It can be observed that this sensor has a initial emission voltage of 10V and a average current of 8.3μA for every silicon tip.The input/output characteristics,hysteresis and degree characteristics of the sample sensor at different degree of the pressure were tested.When the relationships between the output current and degree of the pressure were analyzed,the equation between them was set up,where a lower error less than 10 percent with the range of 10V-15V can be achieved.