Silicon Carbide Ingot Nitrogen Gradient Warpage Control

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Solution Overview

Problem

Silicon carbide ingots cut using the fixed abrasive grain method often result in substrates with significant warpage, making them unsuitable for practical use, despite efforts to suppress warpage.

Innovation Solution

A silicon carbide ingot with a nitrogen concentration gradient between 1×10^16 cm^-4 and 1×10^18 cm^-4 is used, where the gradient is controlled to suppress warpage and prevent cracking during cutting with a wire saw, and the ingot is cut using a diamond abrasive grain wire saw with a specific nitrogen concentration profile to minimize substrate warpage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the fixed abrasive grain method is employed to cut a silicon carbide ingot, then cutting cost is significantly reduced, but warpage of the substrate occurs

Engineering Contradiction:

Improvecutting costVSAvoidsubstrate warpage

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention changes the chemical composition parameters of the silicon carbide ingot by controlling the nitrogen concentration gradient (1×10^16 to 1×10^18 cm^-4) in the growth direction. This parameter modification suppresses warpage during fixed abrasive grain cutting while maintaining the cost advantages of this cutting method.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a non-uniform nitrogen concentration distribution within the silicon carbide ingot, with different nitrogen concentrations at different positions along the growth direction. This local quality variation compensates for cutting-induced stress and reduces substrate warpage.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If the fixed abrasive grain method is employed to cut a silicon carbide ingot, then cutting cost is reduced, but a plurality of substrates with large warpage are produced making them unsuitable for practical use

Engineering Contradiction:

Improvecutting costVSAvoidsubstrate usability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

By modifying the nitrogen concentration gradient parameter in the silicon carbide ingot, the invention ensures that all substrates cut using the fixed abrasive grain method maintain suitable warpage levels for practical use, thereby improving substrate reliability without increasing cutting costs.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If a silicon carbide ingot is cut using a wire saw according to the loose abrasive grain method, then substrate warpage can be suppressed, but cutting cost increases

Engineering Contradiction:

Improvesubstrate warpageVSAvoidcutting cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention modifies the silicon carbide ingot's nitrogen concentration gradient to enable successful cutting using the more cost-effective fixed abrasive grain method, thereby achieving both low cutting cost and acceptable substrate warpage without needing to use the expensive loose abrasive grain method.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10427324B2Silicon carbide ingot and method for manufacturing silicon carbide substrate

Publication Date: 2019.10.01 SUMITOMO ELECTRIC INDUSTRIES LTD

AI summary

A silicon carbide ingot includes an end surface and an end surface opposite to the end surface. In the silicon carbide ingot, the end surface and the end surface face each other in a growth direction, and a gradient of a nitrogen concentration in the growth direction is not less than 1×1016 cm−4 and not more than 1×1018 cm−4.