Trench MOSFET provided with longitudinal shielding grid and processing method thereof

Abstract

The invention belongs to the technical field of semiconductor devices, and discloses a Trench MOSFET provided with a longitudinal shielding grid. The Trench MOSFET provided with the longitudinal shielding grid comprises a substrate, an epitaxial layer, a source adulteration region at the top of the epitaxial layer, a well region below the source adulteration region in the epitaxial layer, a polysilicon grid electrode growing on the upper portion of the epitaxial layer, a gate oxide which is located between the epitaxial layer and the polysilicon grid electrode, a polysilicon source electrode below the polysilicon grid electrode, a sidewall oxide which is located between the epitaxial layer and the polysilicon source electrode, an isolation oxide which is located between the polysilicon grid electrode and the polysilicon source electrode, a surface oxide which covers the polysilicon grid electrode and the source adulteration region, a source contact hole in the inner portion of the epitaxial layer, and a source second adulteration region which encircles the source contact hole and is connected with the well region, wherein the total width of the polysilicon source electrode and the sidewall oxide is larger than the total width of the polysilicon grid electrode and the gate oxide, and the vertical height of the bottom end of the source contact hole is less than the vertical height of the top end of the sidewall oxide. According to the Trench MOSFET provided with the longitudinal shielding grid and the processing method thereof, a longitudinal shielding grid is formed, and the corresponding capabilities of single event resistance are improved.

Description

technical field [0001] The invention relates to the technical field of semiconductor devices, in particular to a Trench MOSFET with a vertical shielding gate and a processing method thereof. Background technique [0002] In the field of semiconductors, a MOSFET device whose gate is fabricated by a trenching process is called a Trench MOSFET. Because of its higher power density and lower on-resistance than traditional VDMOS, it has been widely used. However, when it is applied in the aerospace field, due to the continuous heavy ion radiation in the space environment, it is very easy to induce single event effects, which will cause catastrophic accidents in space systems and limit its application. [0003] When heavy ions bombard the surface of a silicon wafer, a large number of electron-hole pairs will be generated on its moving path. Taking the traditional N-channel TrenchMOSFET as an example, when it is in the blocking state, the electric field in its body is directed to ...

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Problems solved by technology

On the one hand, when the hole current flowing into the well region is too large, so that the voltage drop of the well region exceeds 0.7V, the parasitic transistor composed of the source doped region-well region-epitaxial layer will be turned on. The parasitic triode will undergo secondary breakdown, which will cause excessive concentration of current density and cause single event burnout (SEB) of the device

On the other hand, if too many holes accumulate at the gate oxide Si / SiO2 interface, it is equivalent to adding a transient electric field on the gate dielectric layer, causing the electric field in the gate dielectric layer to exceed the critical breakdown electric field, and the gate dielectric Layer breakdown, that is, the occurrence of single event gate breakdown (SEGR), collectively referred to as the single event effect of the device; both can lead to device damage and failure

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