Folded Trench Gate Layout for Lower Channel Resistance

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Solution Overview

Problem

Existing trench transistors face challenges in reducing the high channel body resistance, particularly in low voltage applications, which affects their efficiency and energy consumption.

Innovation Solution

The design incorporates a nonlinear gate-oxide-semiconductor boundary, increasing the channel width by altering the gate shape to a piecewise linear or periodic rectangular form, while maintaining the same die-size, thereby enhancing the length of the conductive channel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the channel body region is scaled down to reduce resistance, then the transistor resistance decreases, but the channel body region becomes too small to effectively control the drift region

Engineering Contradiction:
Improvetransistor resistanceVSAvoidchannel body control capability
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The patent transitions from a conventional planar gate structure to a three-dimensional folded gate structure. The gate is folded back on itself multiple times within the trench, creating a serpentine path that increases the gate-oxide-semiconductor boundary length without increasing the planar footprint. This dimensional transformation allows the channel body region to maintain adequate size while providing extended control over the drift region through the folded configuration.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The folded gate structure nests multiple gate segments within the same trench volume. Each fold creates additional gate-oxide-semiconductor boundaries that are nested within the three-dimensional space of the trench, effectively multiplying the control interface without requiring additional lateral or vertical space that would reduce the channel body dimensions.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Length of moving object

If the gate shape is altered to increase channel width, then the conductive channel length increases, but the gate structure becomes more complex

Engineering Contradiction:
Improveconductive channel lengthVSAvoidgate structure complexity
Core Design Contradiction:
Length of moving objectVSDevice complexity

Solution Approach 1:

The gate structure is segmented into multiple folded sections, each contributing to the overall gate-oxide-semiconductor boundary length. The gate is divided into discrete segments that are folded back sequentially, with each segment providing additional control boundary while maintaining a modular fabrication approach that manages complexity through repetition of standardized segments.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The gate structure employs curved or angled folds rather than sharp corners, creating a serpentine pattern that smoothly increases the boundary length. The curved geometry of the folded gate segments provides extended channel width while maintaining manufacturability through continuous deposition processes that can accommodate curved patterns.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Data Source

PatentEP4391073A1Nonlinear gate vertical transistor
Publication Date: 2024.06.26 NEXPERIA BV
  • EP4391073A1 patent drawingFigure 1~2
  • EP4391073A1 patent drawingFigure 3~4A
  • EP4391073A1 patent drawingFigure 4B~5

AI summary

A trench transistor with nonlinear gate-oxide-semiconductor boundary layout, and method of manufacture. The trench transistor comprises a gate region, an oxide region adjacent to the gate region, and a semiconductor region adjacent to the oxide region. The semiconductor region comprises a channel region along a gate-oxide-semiconductor boundary. The channel region configured to conduct current along the gate-oxide-semiconductor boundary when the transistor is turned on. The gate-oxide-semiconductor boundary has a nonlinear shape.