Undulating SiC Substrate Groove Design for Warpage Control

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Solution Overview

Problem

The challenge is to create a single crystal substrate for silicon carbide (SiC) that minimizes crystal defects and warpage, enabling the growth of high-quality SiC growth layers, which is difficult due to the high crystallization temperature of SiC and the non-uniform curvature of undulated substrates.

Innovation Solution

A single crystal substrate with a foundation substrate featuring a plurality of grooves, including first and second grooves with specific transverse cross-sectional shapes and orientations, which are formed in a displaced manner to reduce individual differences and promote reproducibility, thereby minimizing deformation and crystal defects in the SiC growth layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If undulations are provided on the substrate to eliminate plane defects, then crystal defects are reduced, but the curvature becomes non-uniform causing warpage and deformation

Engineering Contradiction:

Improvequality of silicon carbide growth layerVSAvoiduniformity of substrate curvature

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The substrate surface is segmented into multiple regions with different groove patterns. First grooves extend in a first direction with specific curvature, while second grooves extend in a second direction (orthogonal or oblique to the first) with different curvature characteristics. This segmentation allows different regions to compensate for each other's deformation, achieving overall uniformity while maintaining the defect-eliminating undulations.

Inventive Principle:

Principle #1Segmentation

2Area of stationary object

If heteroepitaxial growth is used to form SiC on Si substrate, then large diameter substrates can be formed, but crystal defects such as anti-phase boundaries are generated

Engineering Contradiction:

Improvediameter of SiC substrateVSAvoidcrystal defect density

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The invention applies local quality by creating regions with different groove orientations and curvatures across the substrate surface. Each local region has optimized groove patterns tailored to its position, with first grooves having one curvature and second grooves having different curvature. This local optimization allows the entire large-diameter substrate to achieve uniform curvature control and reduced crystal defects simultaneously.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11404269B2Single crystal substrate with undulating ridges and silicon carbide substrate

Publication Date: 2022.08.02 SEIKO EPSON CORP

AI summary

A single crystal substrate is provided and is characterized in that the single crystal substrate has a foundation substrate provided with a plurality of first grooves, which include a first crystal face and a second crystal face opposed to the first crystal face in an inner face thereof, and the extending direction of which is a<110> direction, and a plurality of second grooves, the extending direction of which intersects with the first grooves, and in which the first grooves are formed in a displaced manner in a depth direction, and a transverse cross-sectional shape of the second groove is a shape in which straight lines are open at an opening angle less than 180°. Further, it is preferred that an angle formed by the first crystal face and the second crystal face is more than 70.6°.