Semiconductor Device Stabilizing Diode Voltage via Trench Gate
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Solution Overview
Problem
In semiconductor devices, the separation of anode and body regions requires a wide space, leading to a larger device size, and the forward voltage of diodes is influenced by the turn-on and off of pn junctions at the interface, causing voltage fluctuations.
Innovation Solution
A semiconductor device with a trench gate structure separates the anode and upper IGBT regions, incorporating a crystal defect region with higher defect density in the drift region above the cathode and collector regions, which enhances carrier recombination and stabilizes the forward voltage by reducing current flow through the interface pn junctions, while maintaining a compact device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wide space is secured between the anode region and the body region to separate them, then the separation of anode and body regions is achieved, but the size of the semiconductor device becomes large
Solution Approach 1:
The patent divides the semiconductor device into distinct functional regions separated by a trench structure. The trench physically segments the anode region and body region, allowing effective separation without requiring excessive lateral spacing. This segmentation enables compact device layout while maintaining proper electrical isolation between regions.
Solution Approach 2:
Instead of separating regions purely in the lateral plane (2D), the patent introduces vertical separation using a trench that extends downward into the substrate. This dimensional transition from 2D lateral separation to 3D vertical separation allows regions to be closer horizontally while maintaining electrical isolation through the deep trench structure.
2Area of stationary object
If the anode region and upper IGBT structure are separated by a trench gate structure, then device size is reduced, but the forward voltage of diode becomes influenced by gate potential causing voltage fluctuations
Solution Approach 1:
The patent introduces a crystal defect region with specific properties (higher defect density) localized in the drift region above the cathode and collector regions. This local modification of material quality creates a carrier recombination zone that stabilizes the forward voltage by reducing current flow through interface pn junctions, without affecting the overall compact device structure enabled by the trench gate.
Solution Approach 2:
The crystal defect region acts as an intermediary element that mediates between the trench gate structure and the diode operation. It provides a controlled carrier recombination mechanism that prevents the gate potential from excessively influencing the forward voltage, thereby stabilizing the electrical characteristics while maintaining the benefits of the compact trench gate design.
3Stability of the object's composition
If a crystal defect region is provided in the drift region, then carrier recombination is enhanced and forward voltage is stabilized, but on-voltage of IGBT may rise
Solution Approach 1:
The crystal defect region is strategically localized in specific areas of the drift region (above cathode and collector regions) rather than being uniformly distributed throughout. This localized placement enhances carrier recombination where needed for forward voltage stability while minimizing the impact on IGBT on-voltage, as the defect region does not extend into critical IGBT current paths.
Solution Approach 2:
The patent applies partial action by providing the crystal defect region in only portions of the drift region rather than throughout the entire drift region. This partial implementation achieves sufficient carrier recombination for forward voltage stabilization without excessive recombination that would unduly increase IGBT on-voltage, thus optimizing the trade-off between the two parameters.
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 stabilizes the forward voltage of the diode and suppresses the rise in on-voltage of the IGBT, achieving minimal voltage fluctuations and compact device design by strategically placing the crystal defect region within the drift region.
Implementation Method 1
The crystal defect region having a density of crystal defects higher than a density of crystal defects in a surrounding region of the crystal defect region
Data Source
AI summary
A small semiconductor device having a diode forward voltage less likely to change due to a gate potential is provided. An anode and an upper IGBT structure (emitter and body) are provided in a range in the substrate exposed at the upper surface. A trench, a gate insulating film, and a gate electrode extend along a border of the anode and the upper IGBT structure. Cathode and collector are provided in a range in the substrate exposed at the lower surface. A drift is provided between an upper structure and a lower structure. A crystal defect region extends across the drift above the cathode and the drift above the collector. When a thickness of the substrate is defined as x [μm] and a width of a portion of the crystal defect region that protrudes above the cathode is defined as y [μm], y≥0.007x2−1.09x+126 is satisfied.