SiC Trench Gate Current Spread Region for Low On-Resistance
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Solution Overview
Problem
Shrinking device geometries in semiconductor devices lead to challenges in reducing area-specific on-state resistance (RonxA) while maintaining electric device characteristics and reliability, particularly due to high electric fields in trench dielectrics.
Innovation Solution
A semiconductor device with a trench gate structure in a silicon carbide (SiC) semiconductor body, featuring a source region and a semiconductor region with specific sub-regions and a current spread region, where the doping concentration profile changes along the lateral direction, reducing on-state resistance without affecting channel width or short-circuit time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If device geometries are shrunk to reduce costs and increase device functionalities per unit area, then area-specific on-state resistance (RonxA) is reduced, but reliability deteriorates due to high electric fields in trench dielectrics
Solution Approach 1:
The patent applies local quality by creating a current spread region with a specific doping concentration profile in a localized area adjacent to the trench gate structure. This localized doping modification allows current to spread laterally, reducing the electric field concentration in the trench dielectric while maintaining the overall device geometry shrinkage benefits.
Solution Approach 2:
The patent changes the doping concentration parameter by introducing a current spread region with a doping concentration profile that transitions from a first doping concentration level adjacent to the trench gate structure to a second doping concentration level further away. This parameter change enables better current distribution and reduces peak electric fields without requiring larger device geometries.
2Loss of energy
If device geometries are shrunk to improve electric characteristics, then area-specific on-state resistance (RonxA) is reduced, but other electric device characteristics such as switching characteristics or short-circuit behavior are affected
Solution Approach 1:
The current spread region is localized adjacent to the trench gate structure, affecting primarily the on-state resistance through improved current distribution. The localized nature of this modification minimizes its impact on other electric device characteristics such as switching characteristics or short-circuit behavior, which are determined by other device regions and structures.
Solution Approach 2:
The patent segments the device into distinct functional regions: the trench gate structure, the current spread region with modified doping, and other device regions. This segmentation allows the current spread region to independently optimize on-state resistance without adversely affecting the performance of other device characteristics determined by separate regions.
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 static losses and maintains unchanged short-circuit time, with minimal impact on the gate-to-drain capacitance/gate-to-source capacitance ratio, by optimizing the current spreading and doping concentration profiles.
Implementation Method 1
A doping concentration profile defining the current spread region changes, along the first lateral direction, from a first doping concentration level in the first segment to a second doping concentration level in the second segment
Data Source
AI summary
A semiconductor device is provided. In an example, the semiconductor device includes a trench gate structure in a silicon carbide (SiC) semiconductor body. The semiconductor device includes a source region of a first conductivity type that adjoins the trench gate structure in a first segment. The semiconductor device includes a semiconductor region of a second conductivity type. The semiconductor region includes a first sub-region arranged below the source region in the first segment, and a second sub-region arranged in a second segment that adjoins the first segment. The semiconductor device includes a current spread region of the first conductivity type. The current spread region includes a first sub-region that adjoins the trench gate structure in the first segment at a vertical distance to a first surface of the SiC semiconductor body, and a second sub-region that is spaced from the trench gate structure in the second segment at the vertical distance to the first surface by a lateral distance.