SiC Semiconductor Side Wall {03-3-8} Plane Orientation Control
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Solution Overview
Problem
The channel mobility of semiconductor devices is significantly decreased when the plane orientation of the side wall deviates from the {03-3-8} plane, leading to deteriorated device characteristics due to multiplicity of steps on the side wall surface, which disperses electrons and reduces mobility.
Innovation Solution
A silicon carbide single-crystal surface corresponding to the {03-3-8} plane is formed under specific conditions, allowing it to be used as an active region in the semiconductor device, thereby achieving high channel mobility and stability, even when exposed to heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the side wall plane orientation is deviated by not less than 1° relative to the {03-3-8} plane, then the manufacturing flexibility is improved, but the channel mobility is significantly decreased due to formation of multiple steps on the side wall surface
Solution Approach 1:
The invention changes the critical parameter from plane orientation angle to etching condition parameters (temperature, gas composition, etching time) to control the formation of the {03-3-8} plane. By adjusting etching temperature to 700-1000°C and using specific gas compositions (Cl2-O2 mixed gas), the process achieves precise control over side wall crystal plane formation without requiring tight angular tolerances, thus maintaining high channel mobility while providing manufacturing flexibility.
2Reliability
If a protective cap layer is formed on the side wall before heat treatment, then the side wall is protected from oxidation, but the device structure becomes more complex and additional manufacturing steps are required
Solution Approach 1:
The invention applies self-service by forming a protective silica film directly on the side wall surface through in-situ oxidation during the etching process itself. The side wall surface automatically forms its own protective layer (silica film) when exposed to oxidizing atmosphere at elevated temperatures, eliminating the need for separate cap layer deposition steps while still providing oxidation protection during subsequent heat treatment processes.
3Ease of manufacture
If the side wall surface has multiple steps due to plane orientation deviation, then the manufacturing process is simpler, but electron dispersion increases and channel mobility decreases
Solution Approach 1:
The invention transforms the control approach by changing from geometric parameter control (angle precision) to process parameter control (etching conditions). By precisely controlling etching temperature (700-1000°C), gas composition (Cl2-O2 ratios), and etching time, the process achieves uniform {03-3-8} plane formation across the entire side wall surface, eliminating steps while maintaining process simplicity through automated parameter control.
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
This approach results in a high-quality semiconductor device with enhanced channel mobility and reduced leakage current, eliminating the need for a protective cap layer during activation annealing and enabling higher integration and performance.
Implementation Method 1
by processing a silicon carbide single-crystal under predetermined conditions, a surface corresponding to a {03-3-8} plane (so-called 'semi-polar plane') can be formed as a spontaneously formed surface
Implementation Method 2
even when exposed to heat treatment
Data Source
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AI summary
There are provided a high-quality semiconductor device having stable characteristics and a method for manufacturing such a semiconductor device. The semiconductor device includes: a substrate (1) having a main surface; and a silicon carbide layer (2-5) formed on the main surface of the substrate (1) and including a side surface inclined relative to the main surface. The side surface substantially includes a {03-3-8} plane. The side surface includes a channel region.