SiC Wafer Bevel Geometry for Edge Altered Layer Separation

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Solution Overview

Problem

The existing methods for manufacturing silicon carbide (SiC) wafers face challenges in properly forming an altered layer for chip separation due to laser beam scattering caused by non-orthogonal beveling portions, which hinders efficient separation of chip formation wafers from processed wafers with beveling portions.

Innovation Solution

A method involving the preparation of a silicon carbide wafer with a beveling portion where the area of one side is larger than the other, allowing for easier laser beam irradiation to form an altered layer along the surface direction, facilitating the separation of chip formation wafers from processed wafers using the altered layer as a boundary, and reusing the recycle wafer as a silicon carbide wafer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If a beveling portion is formed at the outer edge portion of the processed wafer, then the area of one side is larger than the other side, but laser beam scattering occurs and the altered layer cannot be properly formed

Engineering Contradiction:

Improvebeveling portion shapeVSAvoidaltered layer formation precision

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

The patent applies asymmetry by designing a beveling portion where the area of one side is intentionally made larger than the other side. This asymmetric configuration allows the laser beam to be irradiated orthogonally to the larger area side, preventing laser beam scattering and enabling proper altered layer formation while maintaining the beneficial beveling shape for chip separation.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent resolves the contradiction by introducing a dimensional consideration - by making the area of one side larger than the other side in the beveling portion, it creates a surface that is orthogonal to the laser beam direction, thereby eliminating scattering issues while preserving the asymmetric shape benefits.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of manufacture

If laser beam is irradiated to form altered layer in processed wafer with beveling portion, then chip separation can be achieved, but laser beam scattering prevents proper altered layer formation

Engineering Contradiction:

Improvechip separationVSAvoidaltered layer formation

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The asymmetric beveling portion design with one side having a larger area than the other enables the laser beam to strike orthogonally at the larger area side, preventing scattering. This ensures reliable altered layer formation while maintaining the asymmetric shape that facilitates easy chip separation along the altered layer boundary.

Inventive Principle:

Principle #4Asymmetry

3Ease of operation

If non-orthogonal beveling portion is used, then chip separation is facilitated, but laser beam scattering occurs hindering altered layer formation

Engineering Contradiction:

Improvechip separation easeVSAvoidlaser beam scattering

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent employs asymmetric geometry where one side of the beveling portion has a larger area than the other. This asymmetric design creates a surface that is orthogonal to the laser beam, eliminating scattering while preserving the beveling shape that facilitates easy chip separation. The larger area side serves as the optimal surface for laser irradiation.

Inventive Principle:

Principle #4Asymmetry

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 enables effective formation of the altered layer up to the edge of the processed wafer, allowing for easy separation of chip formation wafers and efficient reuse of the recycle wafer, thereby improving the manufacturing process and reducing material wastage.

Implementation Method 1

irradiating a laser beam into the processed wafer from the other side of the processed wafer so as to form an altered layer along a surface direction of the processed wafer

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS11881407B2Processed wafer and method of manufacturing chip formation wafer

Publication Date: 2024.01.23 DENSO CORP

AI summary

A method of manufacturing a chip formation wafer includes: forming an epitaxial film on a first main surface of a silicon carbide wafer to provide a processed wafer having one side adjacent to the epitaxial film and the other side; irradiating a laser beam into the processed wafer from the other side of the processed wafer so as to form an altered layer along a surface direction of the processed wafer; and separating the processed wafer with the altered layer as a boundary into a chip formation wafer having the one side of the processed wafer and a recycle wafer having the other side of the processed wafer. The processed wafer has a beveling portion at an outer edge portion of the processed wafer, and an area of the other side is larger than an area of the one side in the beveling portion.