SiC Device Gate Dielectric Shielding via Segmented Doping
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Solution Overview
Problem
Silicon carbide (SiC) devices are vulnerable to breakdown across the gate dielectric, and existing solutions do not provide effective shielding, leading to undesirable results.
Innovation Solution
A silicon carbide device design featuring a gate dielectric with a P-type doped region and an N-type doped region, where the N-type doped region has two portions with different widths and alignments to enhance shielding, reducing electric fields and on-resistance, and improving voltage blocking capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gate dielectric structures are used in SiC devices, then manufacturing is simpler, but the gate dielectric is vulnerable to breakdown due to high electric fields
Solution Approach 1:
The device is segmented into multiple doped regions with different conductivity types (first doped region, second doped region with first and second portions, body region) to distribute and manage electric fields across distinct zones, preventing concentration at any single point that would cause gate dielectric breakdown
Solution Approach 2:
Different portions of the second doped region have different widths and positions tailored to local electric field requirements - the first portion has width less than the first doped region to modulate field distribution, while the second portion is positioned between the first doped region and gate dielectric to provide localized shielding where breakdown risk is highest
2Reliability
If the second doped region has uniform width, then manufacturing is easier, but electric field distribution and on-resistance optimization are compromised
Solution Approach 1:
The second doped region is designed with asymmetric width variation - the first portion has a width less than the first doped region, creating an asymmetric profile that optimizes electric field distribution and on-resistance characteristics while maintaining manufacturability through standard photolithography patterning
3Reliability
If higher doping concentrations are used to reduce on-resistance, then conductivity improves, but electric fields across the gate dielectric increase causing breakdown risk
Solution Approach 1:
The second doped region acts as an intermediary structure between the first doped region and the gate dielectric, with its specific width profile and positioning serving to buffer and redistribute electric fields, allowing higher doping concentrations in the first doped region for low on-resistance while preventing excessive field intensity at the gate dielectric interface
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 design effectively reduces maximum electric fields across the gate dielectric, minimizes on-resistance, and facilitates faster switching by optimizing the trade-off between on-resistance and oxide electric field during high voltage blocking.
Implementation Method 1
The design effectively reduces maximum electric fields across the gate dielectric
Implementation Method 2
a first doped region having a first conductivity type, a body region of the first conductivity type, and a second doped region having a second conductivity type
Data Source
AI summary
In one general aspect, an apparatus can include a silicon carbide (SiC) device can include a gate dielectric, a first doped region having a first conductivity type, a source, a body region of the first conductivity type, and a second doped region having a second conductivity type. The second doped region can have a first portion and a second portion. The first portion can be disposed between the first doped region and the body region and the second portion can be disposed between the first doped region and the gate dielectric. The first portion of the second doped region can have a width less than a width of the first doped region.