A trench gate electrode self-alignment forming method

By employing the growth and etching of first and second mask sidewalls in the trench gate MOSFET, the problems of over-etching or under-etching in the etching process are solved, achieving effective protection of the gate electrode and improving device reliability, making it suitable for mass production.

CN121772309BActive Publication Date: 2026-06-05NANJING THIRD GENERATION SEMICON TECH INNOVATION CENT CO LTD +2
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
NANJING THIRD GENERATION SEMICON TECH INNOVATION CENT CO LTD
Filing Date
2026-03-03
Publication Date
2026-06-05

AI Technical Summary

Technical Problem

In the traditional trench gate MOSFET manufacturing process, the etching process is prone to over-etching or under-etching, which affects the uniformity and reliability of the device threshold voltage, and the photolithography overlay precision limits the reduction of the device cell size.

Method used

By using the growth and etching of the first and second mask sidewalls, and taking advantage of the self-alignment of the sidewall process, the gate electrode in the trench is effectively protected and the gate electrode at the mesa is fully etched, thus avoiding the impact on photolithography accuracy.

Benefits of technology

It achieves effective protection of the gate electrode in the trench and sufficient etching of the gate electrode at the mesa, improving the reliability of the device and allowing for reduction in unit cell size, making it suitable for mass production line applications.

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Abstract

The application discloses a trench gate electrode self-alignment forming method, which comprises the following steps: forming a trench on a semiconductor epitaxial layer drift region; sequentially forming a gate medium and a gate electrode on the semiconductor epitaxial layer drift region, the side wall of the trench and above the trench, and the gate electrode forms a small recess in the middle of the trench; growing a first mask material on the gate electrode and etching, and the first mask is remained at the small recess in the middle of the trench; etching the gate electrode by using the first mask, and the edge of the first mask remained at the small recess forms a local step; growing a second mask material on the gate electrode on the trench and etching, and the second mask side wall is formed at the local step, and the gate electrode is further etched by using the first mask and the second mask side wall formed twice, and the gate electrode on the mesa outside the trench is removed. By growing and etching the first mask and the second mask side wall, the self-alignment advantage of the side wall process is utilized, the effective protection of the gate electrode in the trench and the sufficient etching of the gate electrode at the mesa are realized.
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