The Study Of The Effect Of Strain On NMOSFET Characteristics

The high speed development of computers, communications, sensors, etc technology , which greatly promote the miniaturization of electronic device .Therefore, more and more manpower and material have been invested by many nations. Then,micro-electromechanical system (MEMS) and nanoelectromechanical system (NEMS) processing technology, molecular beam extension ( MBE) technology have experienced rapid growth. Kinds of new microelectronic device are produced. The narrowing of the size of devices, producing all sorts of effects, quantum effect is one of the most important effects. It will make the performance and characteristics of device change. This paper mainly studies the mosfet (FET).Extending the theory based on Mesoscopic piezo-resistive effect, the author puts Meso-transconductance Effect forward, can be simply defined as "the current modulation on the stress". The physical process consists of four components: (1)Under certain condition, the distribution stress of nano structure changes caused by uniform stress; (2)Stress change may cause the built-in electric generation; (3)Built-in electric field will lead to the conduction band level of FET channel change; (4)The change of the conduction band level of channel will cause decreasing of carrier concentration ,which leads to changes of channel current ID. Through the above process, may put a weak mechanical signal that is converted to a high electrical signal.The uniaxial stress is applied on NMOSFET will make I_D-V_DS characteristic, I_D-V_GS characteristic, G_tr-V_GS characteristic change. This is a specific implementation guidance on Meso- transconductance Effect . Using MATLAB software, analysis the impact of stress on NMOSFET characteristics. Finding the G_tr-V_GS characteristic is the best research object. According to the G_tr-V_GS property designs the micro displacement sensor based on Mesoscopic transconductance. Finally the author calculates the sensor's input/output characteristics and sensitivity, as well as compares with classic piezoresistive displacement sensor. The main research contents are as follows:(1) Finding the supporting theory for the Meso-transconductance Effect from the band theory.(2) Studying the influence for the channel curren caused by strain, and analysising the Meso-transconductance Effect.(3) Analysising the stess of the material in order to design reasonable sensors.(4) Calculating sensors sensitivity ,output and input relations of the beam, and making a simple comparison with resemble sensor.This paper proves theoretically the Meso-transconductance effect can improve the sensitivity of sensor ,and for the design of the new type of sensor, provides a train of thought.