Study on The Degradations Produced by Different P-base Diffusion Temperatures on SGT MOSFET With Approximate Threshold Voltage

The degradations of parameter and mechanism produced by different p-base region diffusion temperatures in split-gate-trench MOSFET (SGT-MOS) with approximate threshold voltage is investigated in this paper through Sentaurus TCAD. In SGT-MOS, the threshold voltage (Vth) does not decrease monotonously with the increase of the diffusion temperatures under the gate-controlled range. A snap-back of threshold voltage occurs when the PN junction between p-base region and n-drift region reaches the crescent shaped gate polysilicon manufactured by early wet etching process at a certain temperature, and further temperature rise will make the threshold voltage decrease. Although the Vth of the devices with PNJ in uniform gate region and crescent gate region are similar, the degradations of the on-state resistance and capacitance of SGT-MOS occurs, which reduces the switching frequency of the device.