SiC Trench Gate Thermal Oxidation Insulation
Solution Overview
Problem
Conventional SiC semiconductor devices face challenges in ensuring accurate insulation separation between the gate and source electrodes, leading to potential gate-source leakage due to misalignment and stress-induced cracks in the interlayer insulation film, which complicates mass production.
Innovation Solution
A silicon carbide semiconductor device with a trench gate structure utilizing a thermal oxidation film as the interlayer insulation, which is formed by thermally oxidizing part of the gate electrode, ensuring insulation separation and accurate contact between the source and gate electrodes while minimizing the risk of stress-induced cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PSG or BPSG is used as interlayer insulation film to cover the gate electrode, then insulation between gate and source electrodes is achieved, but misalignment and stress-induced cracks occur leading to gate-source leakage
Solution Approach 1:
The gate electrode itself serves as the source of the interlayer insulation film through thermal oxidation. By oxidizing the gate electrode surface, the insulation film is formed in situ, eliminating the need for separate film deposition and alignment processes. This self-service approach ensures perfect alignment between the gate electrode and the insulation film, preventing misalignment-induced leakage while reducing manufacturing complexity.
Solution Approach 2:
The mechanical process of depositing and patterning separate insulation films is replaced by a thermal oxidation process that chemically transforms the gate electrode surface. This substitution eliminates the mechanical alignment steps and reduces stress-induced cracks associated with film deposition, achieving more reliable insulation separation.
2Ease of manufacture
If conventional interlayer insulation films are used, then gate electrode coverage is achieved, but stress-induced cracks complicate mass production
Solution Approach 1:
The gate electrode serves as both the structural element and the source material for the insulation film. Through thermal oxidation, the gate electrode surface transforms into an insulating layer, eliminating the need for separate film deposition processes that introduce stress and cracks. This approach simplifies manufacturing while improving reliability.
Solution Approach 2:
The physical and chemical parameters of the gate electrode are changed through thermal oxidation, transforming it from a conductive metal to an insulating oxide layer. This parameter change occurs in situ without introducing external films that could cause stress-induced cracks, thereby improving mass production capability while maintaining reliability.
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 thermal oxidation film effectively insulates the gate and source electrodes, preventing leakage and allowing for accurate source electrode contact, thereby enhancing the reliability and manufacturability of SiC semiconductor devices.
Implementation Method 1
A silicon carbide semiconductor device with a trench gate structure utilizing a thermal oxidation film as the interlayer insulation, which is formed by thermally oxidizing part of the gate electrode
Data Source
AI summary
A silicon carbide semiconductor device includes a semiconductor element with a MOS structure having: a substrate; a drift layer on the substrate; a base region on the drift layer; a source region on the base region; a trench gate structure having a gate insulation film and a gate electrode in a gate trench disposed from a surface of the source region to be deeper than the base region; an interlayer insulation film covering the gate electrode and the gate insulation film; a source electrode on the interlayer insulation film, the source region and the base region; and a drain electrode. The semiconductor element flows a current when a gate voltage is applied to the gate electrode and a channel region is provided in a portion of the base region in contact with the trench gate structure.