Trench type power semiconductor element and manufacturing method thereof

Abstract

The invention discloses a groove power semiconductor element and manufacture method thereof. A gate structure of the groove power semiconductor element includes a gate insulation layer, a lamination layer and a gate. The gate insulation layer covers the inner wall face of a groove. The lamination layer covers the lower half part of the gate insulation layer. The gate is disposed in the groove andis isolated from the lamination layer and an epitaxial layer through the gate insulation layer. The gate includes a lower doping zone surrounded by the lamination layer and an upper doping zone disposed on the lamination layer and the doping zone. A PN interface is formed between the upper doping zone and the lower doping zone. The impurity concentration in the upper doping zone decreases gradually from the outer periphery of the upper doping zone towards the inner part of the upper doping zone. Since the PN interface can generate an interface capacitor connected with a parasite capacitor in series under reverse biased voltage, the equivalent capacitance of the gate / drain can be reduced.

Description

technical field [0001] The invention relates to a power semiconductor element and a manufacturing method thereof, in particular to a trench power transistor and a manufacturing method thereof. Background technique [0002] The existing power metal oxide semiconductor field effect transistor (Power Metal Oxide Semiconductor Field Transistor, Power MOSFET) mostly adopts a vertical structure design to increase device density. The operating loss of power MOSFETs can be divided into two categories: switching loss and conducting loss. The gate / drain capacitance (Cgd) is an important parameter affecting switching loss. . If the gate / drain capacitance value is too high, the switching loss will increase, which will limit the switching speed of the power MOSFET, which is not conducive to the application in high-frequency circuits. Contents of the invention [0003] The technical problem to be solved by the present invention is to reduce the gate / drain capacitance value of the tren...

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Problems solved by technology

[0003] The technical problem to be solved by the present invention is to reduce the gate / drain capacitance value of the trench power semiconductor element, and to avoid conductive impurities in the upper and lower doped regions of the gate caused by multiple thermal diffusion processes Mutual diffusion prevents the gate from having a PN junction and affects device characteristics

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