Trench type MOSFET (metal-oxide-semiconductor field effect transistor) device

Abstract

The invention discloses a novel trench type MOSFET (metal-oxide-semiconductor field effect transistor) device and a manufacturing method thereof. A concave interface is formed between a body area and a semiconductor substrate, so that the part under source metal contact, of the body area is thinner than other parts of the body area. The most concave position E of the concave interface is positioned under the source metal contact so as to lead a reversed electric field to be gathered at the most concave position. A heavily doped region positioned under the source metal contact also can be formed in the body area so as to reduce the resistance. When the MOSFET is shut off, a reverse current is generated, flows through the heavily doped region from the most concave position and reaches the source metal contact, so that the influence of an equivalent parasitic transistor B on the shutoff of the MOSFET is reduced and the lower voltage drop is generated. In the novel trench type MOSFET device disclosed by the invention, the parasitic transistor is effectively controlled, and the UIS performance of the trench type MOSFET is improved.

Description

technical field [0001] The present invention relates to a MOSFET device, more specifically, to a trench gate MOSFET device. Background technique [0002] Trench-gate metal-oxide-semiconductor field-effect transistor (MOSFET) devices are widely used in the field of power management due to their high performance and low cost. When trench gate MOSFET devices are used in circuits with inductive loads, their unclamped inductive switching (UIS) performance is an important parameter affecting the performance of trench gate MOSFET devices. [0003] Such as figure 1 As shown, when the MOSFET M is turned on, the inductor L discharges through the MOSFET M. When the MOSFET M is turned off, since the inductor current cannot change suddenly, the parasitic diode A in the MOSFET M is broken down, and the inductor current is discharged through the parasitic diode A. UIS means that when the output terminal of the MOSFET is connected with an inductive device that cannot be clamped by other ...

AI Technical Summary

Problems solved by technology

Since the P-type body region is lightly doped, its resistance is large, so the forward voltage drop is also large, which is greater than the base-emitter turn-on voltage drop V of the equivalent parasitic transistor B BEon , so that the parasitic transistor B is turned on, and the current is amplified, resulting in runaway

At this point, the gate voltage will no longer be able to turn off the MOSFET device, making the MOSFET device permanently damaged

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