Trench Gate Power Device with Conductive Bridges
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Solution Overview
Problem
Existing power devices with trench gate structures face limitations in switching control due to high gate resistance and gate charge, which affect their performance, especially at high switching speeds.
Innovation Solution
A method for manufacturing a power device with a trench gate structure that includes a conductive gate structure made by covering the trench sidewalls and bottom with a first insulating material, followed by a second conductive coating layer and a conductive central region of different resistivity, interconnected by conductive bridges to separate and intercouple the gate electrode and signal transmission line, allowing for adjustable gate resistance and optimized performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a trench gate structure is used to increase integration scale and current density, then device conductance is improved, but gate resistance and gate charge increase, worsening switching control
Solution Approach 1:
The gate structure is segmented into multiple conductive regions with different materials and resistivities. The gate electrode is divided into a first conductive region (lower resistivity) and a second conductive region (higher resistivity), allowing independent optimization of current conduction and switching control characteristics.
Solution Approach 2:
Different regions of the gate structure are assigned different material properties and resistivities to perform different functions. The first conductive region provides low resistance for current conduction, while the second conductive region provides higher resistance for improved switching control, achieving local optimization of electrical characteristics.
2Speed
If the gate electrode extension is limited to trench vertical walls to reduce gate-drain capacitance, then switching speed is improved, but the conductive path and current density are reduced
Solution Approach 1:
The gate structure utilizes both vertical and horizontal dimensions effectively. The gate electrode extends along the trench vertical walls to minimize capacitance, while additional conductive regions are positioned at the trench bottom and connected via conductive bridges, creating a three-dimensional conductive network that maintains current density without increasing gate-drain capacitance.
Solution Approach 2:
Conductive bridges serve as intermediary elements connecting the gate electrode on trench walls to the conductive regions at the trench bottom. These bridges provide additional current paths without requiring the gate electrode to extend horizontally, thus maintaining low gate-drain capacitance while improving current density.
3Ease of manufacture
If a single conductive material is used for the gate structure, then manufacturing is simplified, but the ability to independently optimize gate resistance and conductance is limited
Solution Approach 1:
The gate structure employs composite materials with different electrical properties. The first conductive region uses a material with lower resistivity for efficient current conduction, while the second conductive region uses a material with higher resistivity for improved switching control, creating a composite gate structure that achieves multiple electrical performance targets simultaneously.
Data Source
AI summary
A power device integrated on a semiconductor substrate and having a plurality of conductive bridges within a trench gate structure. In an embodiment, a semiconductor substrate includes a trench having sidewalls and a bottom, the walls and bottom are covered with a first insulating coating layer which then also includes a conductive gate structure. An embodiment provides the formation of the conductive gate structure with covering at least the sidewalls with a second conductive coating layer of a first conductive material. This results in a conductive central region of a second conductive material having a different resistivity than the first conductive material forming a plurality of conductive bridges between said second conductive coating layer and said conductive central region.