Shield gate groove type field effect transistor with variable doping concentration structure and preparation method of shield gate groove type field effect transistor

Abstract

The invention relates to a shield gate groove type field effect transistor with a variable doping concentration structure. The shield gate groove type field effect transistor comprises a substrate region, a drift region, a base body region, a source region, a groove region, a drain electrode and a source electrode, the trench region comprises a shield gate, a control gate, an insulating layer and a metal gate; the shield grid and the drift region are of a variable doping concentration structure, the doping concentration of the drift region is gradually reduced from top to bottom, and the doping concentration of the shield grid is gradually reduced from top to bottom. When the transistor is blocked in the forward direction, the electric field between the third-stage drift region and the corner of the trench region is weakened. Therefore, the shield gate trench type field effect transistor with the variable doping concentration structure can balance the peak electric field of the voltage withstanding layer at the interface of the substrate region and the drift region, so that the peak value of the electric field is improved, the breakdown voltage is improved, and the specific on-resistance is reduced.

Description

technical field [0001] The present application relates to the technical field of power semiconductor devices, and in particular, to a shielded gate trench field effect transistor with a variable doping concentration structure and a preparation method thereof. Background technique [0002] Shielded gate trench field effect transistors (Split Gate Trench, SGT) have been widely used in important low-voltage fields such as power management. SGT has high channel density and good charge compensation effect. In addition, the shielded gate structure effectively isolates the coupling between the control gate and the drain, thereby significantly reducing the transfer capacitance. [0003] Therefore, SGT has lower specific on-resistance, smaller conduction and switching losses, and higher operating frequency. [0004] In the SGT device, due to the electric field concentration effect and the high polysilicon doping concentration of the shielding gate, when the SGT device is blocked in...

AI Technical Summary

Problems solved by technology

[0004] In the SGT device, due to the electric field concentration effect and the high doping concentration of polysilicon in the shield gate, when the SGT device is forward-blocked, the charge flux emitted by the ionized donor in the withstand voltage region is concentrated in the trench region shield At the corner of the gate, the peak voltage at the corner of the shield gate in the trench area is higher, and it is easier to be broken down here

Images