SiC Trench Gate Body Doping for DIBL and Threshold Stability
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Solution Overview
Problem
Silicon carbide (SiC) devices face challenges in improving device parameters, particularly in reducing the contribution of channel resistance to on-state resistance and mitigating drain-induced barrier lowering (DIBL) effects.
Innovation Solution
A trench gate structure in silicon carbide devices is enhanced by forming a heavily doped body portion with a dopant concentration at least 150% of the reference concentration and a horizontal extension of at least 20% of the body region, using a tilted implantation method to reduce depletion region penetration and maintain gate threshold voltage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional SiC device structure is used, then the device can achieve high breakdown field strength and lower on-state resistance, but the channel resistance contribution to overall on-state resistance remains high and drain-induced barrier lowering effects are significant
Solution Approach 1:
The patent applies local quality by creating a heavily doped body portion with dopant concentration at least 150% of the reference concentration in a specific region of the body region, rather than uniformly doping the entire body. This localized heavy doping directly below the source zone and distant from the active sidewall targets the specific area where depletion region penetration causes DIBL effects, improving device parameters without uniformly increasing channel resistance throughout the entire device structure
Solution Approach 2:
The patent changes the dopant concentration parameter in the body region by forming a heavily doped body portion with dopant concentration at least 150% of the reference dopant concentration. This parameter change in the specific horizontal plane reduces the depletion region penetration and mitigates DIBL effects while maintaining the overall device structure and other doping parameters unchanged
2Object-affected harmful factors
If the dopant concentration in the body region is increased to reduce depletion region penetration, then DIBL effects are mitigated, but the gate threshold voltage stability may be compromised
Solution Approach 1:
The patent applies local quality by restricting the heavy doping (at least 150% reference concentration) to a specific body portion that is distant from the active sidewall and located directly below the source zone. This localized approach increases dopant concentration only where needed to reduce depletion region penetration, while leaving other regions with standard doping levels, thereby maintaining gate threshold voltage stability
Solution Approach 2:
The patent segments the body region into different portions with different doping levels: a heavily doped body portion (at least 150% reference concentration) located directly below the source zone, and other body region areas with reference dopant concentration. This segmentation allows the heavily doped portion to reduce depletion region penetration and DIBL effects, while the rest of the structure maintains proper electrical characteristics and gate threshold voltage stability
3Reliability
If a heavily doped body portion is formed with extended horizontal coverage, then DIBL effects are reduced and electrical characteristics improve, but the manufacturing complexity increases
Solution Approach 1:
The patent changes the dopant concentration parameter in a specific horizontal plane to at least 150% of the reference concentration, creating a heavily doped body portion with defined horizontal extension (at least 20% of total body region extension). This parameter change achieves improved electrical characteristics by reducing DIBL effects while maintaining a clear, quantifiable manufacturing specification that limits process complexity
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 drain-induced barrier lowering and improves the electrical characteristics of silicon carbide devices by minimizing depletion region extension and maintaining stable gate threshold voltage.
Implementation Method 1
Dopants are implanted into a first body portion of the body region, wherein the first body portion is located directly below the source zone and distant from the active sidewall
Data Source
AI summary
A silicon carbide device includes a silicon carbide body with a trench gate structure that extends from a first surface into the silicon carbide body. A body region is in contact with an active sidewall of the trench gate structure. A source region is in contact with the active sidewall and located between the body region and the first surface. The body region includes a first body portion directly below the source region and distant from the active sidewall. In at least one horizontal plane parallel to the first surface, a dopant concentration in the first body portion is at least 150% of a reference dopant concentration in the body region at the active sidewall and a horizontal extension of the first body portion is at least 20% of a total horizontal extension of the body region.