Trench type power transistor and manufacturing method thereof

Abstract

The invention provides a trench type power transistor, which includes a semiconductor substrate, wherein the semiconductor substrate comprises at least one active part, the at least one active part has a gate trench structure, and the gate trench structure is provided with a surrounding wall which extends downwards from the top surface and defines a gate trench, a first isolation layer which is made of an insulating material and extends to cover the surface of the surrounding wall, an isolation unit which is made of an insulating material, is filled in the gate trench and covers the first isolation layer, a shielding electrode located at the bottom of the gate trench, and a gate electrode located above the shielding electrode. By means of the structural design of the isolation unit, the fourth isolation layer wraps the peripheral face, adjacent to the shielding electrode, of the gate electrode so as to isolate the gate electrode from the nitride material, so that the defect that due tothe fact that the gate electrode makes contact with nitride or is too close to the nitride, interaction is generated, and element characteristics are affected can be overcome. The invention also provides a method for manufacturing the trench type power transistor.

Description

technical field [0001] The invention relates to a power transistor and a manufacturing method thereof, in particular to a trench type power transistor and a manufacturing method thereof. Background technique [0002] Power transistors (Power MOSFETs) can be applied to digital circuits or analog circuits. Therefore, they have become the mainstream of power components and are widely used in different electronic components. [0003] Power transistors can be divided into horizontal type and vertical type according to the current flow path. Among them, in terms of vertical power transistors, the current common ones are trench gate power MOSFETs (Trench Gate Power MOSFET, or UMOSFET), V-groove metal oxide half field effect transistor (VMOSFET), or vertical double diffused metal oxide half field effect transistor (VDMOSFET). As for the trench power transistor, because its U-shaped trench shape can effectively reduce the on-state resistance (on-state resistance) and improve the ter...

AI Technical Summary

Problems solved by technology

However, because the temperature of the thermal oxidation process is relatively high (usually between 950° C. and 1150° C.), when the number of thermal oxidations is high, the top region of the gate trench is likely to become larger due to oxidation, resulting in the adjacent gate trench The distance (mesa) becomes smaller, so that the distance between the adjacent gate trench and the adjacent gate trench is too close when the conductive plug is fabricated later, which affects the threshold voltage (threshold voltage, Vth) of the device and easily causes process variability. Not conducive to the production of high-density components

Images