SiC Semiconductor Device Trench Orientation for High Channel Mobility
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Solution Overview
Problem
Existing silicon carbide semiconductor devices do not achieve sufficiently high channel mobility, which is essential for improved performance in MOS devices.
Innovation Solution
A silicon carbide semiconductor device with a silicon carbide layer having a surface covered by an insulation film, featuring trenches with specific plane orientations that provide high channel mobility, including first to sixth side faces with off orientations to the {0001} and {03-38} planes within specific ranges, and a gate electrode structure for enhanced control and mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a {0001} plane is used for the silicon carbide surface, then the device structure is simple and easy to manufacture, but the channel mobility is insufficient due to high density of dangling bonds and increased interface states
Solution Approach 1:
The patent changes the crystallographic plane orientation parameter from the conventional {0001} plane to the {03-38} plane (or planes within ±5° of this orientation). This parameter change in plane orientation reduces the density of dangling bonds at the surface, thereby reducing interface state density and improving channel mobility while maintaining manufacturing feasibility through controlled off-angle cutting.
2Reliability
If a {03-38} plane is used to increase channel mobility, then electron mobility improves due to reduced dangling bonds, but the manufacturing precision requirements become more stringent to maintain the specific off-angle orientation
Solution Approach 1:
The patent introduces an asymmetric off-angle orientation relative to the ideal {03-38} plane, specifying a range of ±5° from the (000-1) plane direction. This asymmetric approach allows manufacturing tolerance while maintaining the essential benefit of reduced dangling bonds, balancing performance requirements with manufacturing capabilities.
Solution Approach 2:
The patent defines a specific range for the off-angle parameter (within ±5° to the <11-20> direction and within 3° of the {03-38} plane) that optimizes channel mobility while accommodating manufacturing variations. This parameter specification provides a practical window for production while ensuring performance targets are met.
3Reliability
If multiple different plane orientations are provided in the trench structure, then channels with high mobility in different directions are achieved, but the device complexity increases
Solution Approach 1:
The patent divides the trench structure into multiple side faces, each with different plane orientations (first side face with one orientation, second side face with another orientation). This segmentation allows each face to provide high mobility channels in different directions, achieving omnidirectional high mobility performance while using a relatively simple trench geometry that can be manufactured with standard processes.
Data Source
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AI summary
A silicon carbide semiconductor device (100) includes an insulation film (126), and a silicon carbide layer (109) having a surface covered with the insulation film (126). The surface includes a first region (R1). The first region (R1) has a first plane orientation at least partially. The first plane orientation is any of a (0-33-8) plane, (30-3-8) plane, (-330-8) plane, (03-3-8) plane, (-303-8) plane, and (3-30-8) plane.