Split gate trench power semiconductor device

Abstract

The present invention discloses a split-gate trench power semiconductor device which comprises: an active region arranged on a semiconductor substrate, wherein the active region comprises a first well region and a second well region which are longitudinally stacked in the direction from the surface of the semiconductor substrate to the bottom of the semiconductor substrate; and one or more than one true gate grooves which are formed by etching and penetrate through the first well region and the second well region, wherein split type polycrystalline silicon true gates are arranged in the true gate grooves and comprise polycrystalline silicon main true gates and polycrystalline silicon auxiliary true gates, and the polycrystalline silicon main true gates and the polycrystalline silicon auxiliary true gates are arranged close to the tops and the bottoms of the grooves in a separated mode respectively. The polycrystalline silicon main true gates are control gates used for being connected with an external gate drive circuit, and the polycrystalline silicon main true gates and the polycrystalline silicon auxiliary true gates, the polycrystalline silicon true gates and the side wall of the true gate grooves and the polycrystalline silicon true gates and the bottom of the true gate grooves are isolated through interlayer media. According to the invention, the polysilicon gate in the strip-shaped groove is split to form the split gate, so that the stray capacitance is reduced, different electric connections are adopted, and the thickness of the oxide layer is set, so that the overall optimization of the chip performance is realized.

Description

technical field [0001] The invention relates to the technical field of power semiconductor devices, in particular to a split gate trench power semiconductor device. Background technique [0002] Insulated gate bipolar transistor (IGBT) is the only semiconductor device that combines MOSFET and bipolar transistor so far. It has the characteristics of high input impedance and fast response of MOSFET tube, and is widely used in rail transit, smart grid, electric Automobiles, new energy development and other fields. [0003] With the rapid development of IGBT technology, the trench gate can change the current channel from the surface horizontal to the vertical in the body, effectively eliminate the JFET effect in the planar gate body, and reduce the cell size so that the channel density is no longer limited by the chip surface area. The limit greatly increases the cell density, thereby greatly increasing the chip current density and reducing the chip on-state loss. However, as ...

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Problems solved by technology

However, as the trench gate density increases, it will lead to higher parasitic capacitance of the chip, which will have an adverse effect on the turn-on and turn-off of the chip, increase the switching loss of the chip, and lead to a compromise between the on-state loss and switching loss of the chip. out of balance

[0004] In addition, during the long-term use of power semiconductor devices, the oxide layer at the bottom of the trench is under high pressure for a long time, and the plasma in the body will repeatedly impact the oxide layer at the bottom of the trench during the chip switching process, affecting the reliability of the chip for long-term use

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