The Electrical Characteristics Research And Simulation Design Of Strained SGT MOSFET

Strained silicon technology is a key technology of modern semiconductors,which can effectively improve the carrier mobility and performance of the device.Strained silicon technology has been applied to advanced CMOS technology on a large scale.At the same time,power semiconductor devices can also use strained silicon technology to optimize the trade-off relationship between on-resistance and breakdown voltage,breaking the"silicon limit".SGT(Shield Gate Trench)MOSFET has important applications in the field of discrete power semiconductors.At present,most researchers improve the electrical performance by changing the structure and process of SGT MOSFET.Corresponding to the application of silicon technology in SGT MOSFET and its Process realization has not been reported.This thesis will focus on the study of the impact of mechanical strain on the key electrical characteristics of SGT MOSFETs,and strained silicon technology will be simulated and designed in SGT MOSFET devices.In this thesis,the method of bending the wafer is used to study the changes of key electrical parameters of 40V SGT MOSFET under four forms of mechanical strain(including biaxial tensile strain,biaxial compressive strain,uniaxial tensile strain,and uniaxial compressive strain).Under uniaxial and biaxial compressive strain,the current of the device increases,and under uniaxial and biaxial tensile strain,the current of the device decreases,and the effect of strain is opposite to that of traditional CMOS devices.The effect of biaxial strain is more significant than uniaxial strain.Under200 MPa biaxial compressive strain,the current is increased by 6.93%,and under 200 MPa biaxial tensile strain,the current is reduced by 7.05%.At the same time,the experiment also shows that the four forms of mechanical strain have almost no effect on the threshold voltage,breakdown voltage,gate capacitance,and switching characteristics of the SGT MOSFET.Subsequently,the multiphysics simulation software CMOSL is also combined in this thesis to simulate the distribution of mechanical strain in the device during the experiment,and brought the strain distribution data into the TCAD simulation software to verify the accuracy of the experimental results.The simulation results show that when the device is subjected to uniaxial and biaxial compressive strain,the current density of the vertical channel region and part of the drift region has increased significantly.It is revealed that the fundamental reason for the mechanical strain to change the static electrical characteristics of the device is to change the carrier mobility of the vertical channel region and part of the drift region of the SGT MOSFET device.Furthermore,the design of SGT MOSFET using strained silicon technology is simulated in this thesis.By optimizing the existing process,a Si N layer containing 2GPa compressive stress is introduced into the trench gate,which can introduce a local area of the order of 10~8Pa in the vertical channel and part of the drift region to improve the electron mobility.The on-resistance of the original SGT MOSFET device can be effectively reduced without changing the breakdown voltage and threshold voltage.When the gate voltage is 5V,the on-resistance of the device is reduced by 15%,which meets the design requirements.