Trench gate of trench type device preparation method and trench gate of trench type device

Abstract

The invention provides a trench type device trench gate preparation method and a trench type device trench gate. The method comprises the steps: growing a mask layer on a substrate (10), and etching the mask layer to form an opening (41); etching the mask layer at the opening (41) by adopting a wet etching process, and then etching the substrate (10) to form a trench (40) and a cutting surface atthe top of the trench (40); and removing the mask layer, sequentially growing a gate oxide layer (50) and a gate (60) on the side wall of the trench (40), the cutting surface and the front surface ofthe substrate (10). By forming the trench (40) and the cutting surface at the top of the trench (40), sharp corners are prevented from being formed at the top of the trench, the breakdown voltage at the cutting surface is improved, the breakdown voltage of the trench type device is improved, the probability that the trench type device is broken down and fails is greatly reduced, the service life of the trench type device is prolonged, and the cost is saved.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a preparation method for a trench gate of a trench type device and the trench gate of a trench type device. Background technique [0002] Power devices mainly include high-power transistors, thyristors, bidirectional thyristors, GTOs, metal semiconductor field effect transistors MOSFETs, insulated gate bipolar transistors IGBTs, etc., in which both MOSFETs and IGBTs use gates to control devices to realize device switching. According to its structural characteristics, the gate can be divided into planar type and trench type. The planar type gate is placed on the substrate surface and the trench type gate is usually perpendicular to the substrate surface. [0003] In the planar gate structure, the gates are distributed on the surface of the substrate, the channels with open channels are below the gates and parallel to the gates, and there are JEFT regions between adjacent ch...

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Problems solved by technology

[0004] In the prior art, in the process of preparing the trench gate of the trench device, after the dielectric layer is formed, the trench is formed by photolithography and dry etching. The apex angle of the formed trench is usually very sharp, close to At a 90° right angle, charges are easy to accumulate and form a strong electric field. When an external voltage is applied, electric field breakdown is likely to occur, resulting in gate leakage. On the sidewalls and bottom of the trench, it is not easy to form charge accumulation. Prone to breakdown, i.e. low breakdown voltage at trench corners

The breakdown voltage of the top corner of the trench also determines the breakdown voltage of the trench device. Due to the low breakdown voltage of the top corner of the trench, the trench device is easily broken down and fails.

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