Trench Power Semiconductor Shielding Electrode Field Distribution
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Solution Overview
Problem
Conventional power MOSFETs suffer from high drain-to-gate capacitance, leading to increased switching loss and limited suitability for high-frequency circuits, which is not effectively addressed by existing shielding electrode configurations.
Innovation Solution
A trench power semiconductor component with a shielding electrode and a trench gate structure that includes an intermediate dielectric layer with a bottom opening and an inner dielectric layer filling the bottom opening, made of different materials, to reduce the electric field distribution density at the bottom of the cell trench during reverse bias, thereby enhancing breakdown voltage without adversely affecting on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shielding electrode is located in the lower half part of the gate trench, then the gate-to-drain capacitance is reduced and breakdown voltage is increased, but the electric field distribution density at the bottom of the cell trench increases during reverse bias
Solution Approach 1:
A first dielectric layer is introduced as an intermediary between the shielding electrode and the n- type epitaxial layer. This intermediate dielectric structure mediates the electric field distribution, preventing direct high-field contact between the shielding electrode and the semiconductor material, thereby reducing peak electric field density while maintaining the shielding electrode's voltage-enhancing function
Solution Approach 2:
The patent changes the physical and material parameters of the interface between the shielding electrode and the epitaxial layer by introducing a dielectric layer with specific permittivity and thickness characteristics. This parameter modification alters the electric field distribution profile, spreading the field more evenly and reducing peak density at the trench bottom
2Ease of manufacture
If a conventional shielding electrode configuration is used, then manufacturing is simplified, but drain-to-gate capacitance remains high leading to increased switching loss
Solution Approach 1:
The gate trench structure is segmented into functional zones: the shielding electrode occupies the lower half for voltage control, while the upper half contains the gate electrode for signal control. The dielectric layers create additional segmentation that isolates electric fields. This spatial segmentation reduces capacitive coupling between gate and drain, lowering switching loss while maintaining manufacturability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces the electric field distribution density at the bottom of the cell trench, improving breakdown voltage and reducing on-resistance, thus enhancing switching efficiency and making the trench power semiconductor component more suitable for high-frequency applications.
Implementation Method 1
an intermediate dielectric layer having a bottom opening located at a bottom side of the at least one cell trench and an inner dielectric layer filling the bottom opening
Data Source
AI summary
The present disclosure provides a trench power semiconductor component and a manufacturing method thereof. The trench gate structure of the trench power semiconductor component is located in the at least one cell trench that is formed in an epitaxial layer. The trench gate structure includes a shielding electrode, a gate electrode disposed above the shielding electrode, an insulating layer, an intermediate dielectric layer, and an inner dielectric layer. The insulating layer covers the inner wall surface of the cell trench. The intermediate dielectric layer interposed between the shielding electrode and the insulating layer has a bottom opening. The inner dielectric layer interposed between the shielding electrode and the intermediate dielectric layer is made of a material different from that of the intermediate dielectric layer, and fills the bottom opening so that the space of the cell trench beneath the shielding electrode is filled with the same material.