Analytically modeling electric field of shielded gate trench metal-oxide-semiconductor field effect transistor

Abstract

SGT-MOSFET introduces a longitudinal shielding gate connected to the source inside the body, which can assist in depleting the drift region. Its voltage withstand principle is different from traditional VUMOSFET. SGT-MOSFET will generate two electric field peaks inside the body, which will further optimize the electric field strength distribution of the device and increase the breakdown voltage of the device. Therefore, SGT-MOSFET not only has the advantages of low conduction loss of CCMOSFET, but also has lower switching loss. The influence of structural parameters such as the width of the mesa, the thickness of the field oxygen, the depth of the trench and the doping concentration on the electric field strength distribution of SGT-MOSFET is not independent of each other. The more parameters are, the more complex the correlation of their influence on the electric field strength distribution is. In this paper, 110V SGT-MOSFET is taken as the research object. Through numerical simulation, theoretical analysis and analytical modeling, the withstand voltage principle of different structures and the correlation between structural parameters and electric field strength distribution are studied; the analytical model of the electric field related to various structural parameters of the device is established, which provides a theoretical basis for the design of the device structure. The analytical model of electric field under low current is modified by introducing avalanche carriers, so that the modified analytical results can better match the simulation results. The field oxygen thickness at the optimal electric field is extracted as 0.68µm by the modified analytical model of the electric field. Compared with the product of SGTMOSFET with 0.58µm field oxygen thickness, at the optimal field oxygen thickness of 0.68µm, the on-resistance of the device is reduced because the on-area of the device is increased; the electric field distribution is more uniform, so the device breakdown voltage increases; the gate-source capacitance decreases and the gate-drain capacitance is almost no change, so the gate-source charge decreases and the gate-drain charge is almost no change, while the total gate charge decreases. As a result, the optimal value parameter FOM<sub>1</sub> of the device is increased by 18.9%, and the optimal value parameter FOM<sub>2</sub> is reduced by 8.5%. Therefore, the static and dynamic characteristics of the device are significantly promoted, and the performance of the corresponding products is greatly improved.

Establishment of analytical model for electrostatic discharge gate-to-source capacitance of power metal-oxide-semiconductor field-effect transistor

“…SGT-MOSFET在HBM模型下仿真的正反 1.0T10 20 3.9T10 16 1.5T10 13 5.9T10 9 2.3T10 6 9.0T10 2 hDensity/cm -3 7.0T10 18 1.9T10 15 5.1T10 11 1.4T10 8…”