Split-gate MOS device and preparation method thereof

Abstract

The invention relates to the technical field of semiconductors, and discloses a split-gate MOS device and a preparation method thereof. The split-gate MOS device comprises a substrate, a first epitaxial layer, a second epitaxial layer and a third epitaxial layer of a first conduction type are sequentially arranged on the substrate from bottom to top, the doping concentration of the second epitaxial layer is greater than that of the first epitaxial layer, the doping concentration of the first epitaxial layer is larger than that of the second epitaxial layer, the doping concentration of the second epitaxial layer is larger than that of the third epitaxial layer, and the first epitaxial layer, the second epitaxial layer and the third epitaxial layer form a drift region of the split-gate MOS device. Firstly, the second epitaxial layer with high doping concentration can enhance the electric field modulation effect of the drift region and increase the withstand voltage of the split-gate MOS device; secondly, electric field lines can be prevented from being accumulated on two sides of the bottom of the groove, and the split-gate MOS device is prevented from being broken down on two sides of the bottom of the groove in advance when withstanding voltage; and thirdly, the on-resistance of the device is reduced.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a split gate MOS device and a preparation method thereof. Background technique [0002] In the traditional trench MOSFET structure, the gate and drain regions are only separated by gate oxide, so the traditional trench MOSFET will limit its application due to high switching loss caused by high gate-to-drain capacitance. [0003] In the evolution of MOSFETs, split-gate (SGT) devices reduce switching losses by adding a source electrode between the gate and drain. The trench of the split gate structure has two parts: the upper electrode is the control gate electrode, and the lower electrode is the shield gate source electrode, which is connected to the source through a separate contact, which is equivalent to extending the field plate inside the device to balance the charge in the drift region . Most of the existing split-gate devices grow one or two epitaxial layers on the...

AI Technical Summary

Problems solved by technology

Most of the existing split-gate devices grow one or two epitaxial layers on the substrate, and then fabricate MOS devices on one or both sides of the epitaxial layers, although compared with the existing traditional trench MOSFET, its performance parameters are obtained However, its parameters such as device withstand voltage, anti-breakdown capability and overall on-resistance still cannot meet the requirements of some occasions.

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