Laser Wafer Separation with Protective Layer for SiC Chip Thinning

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Solution Overview

Problem

Existing methods for processing wafers with high Mohs hardness, such as silicon carbide, result in significant wear of grindstones and require excessive processing time due to limitations in forming efficient separation start positions, which can damage devices on the wafer surface and necessitate inefficient grinding.

Innovation Solution

A method involving the formation of a protective layer using a first laser beam at a specific height within the wafer, followed by a second laser beam to create a separation start position, reducing the likelihood of device damage and allowing for more efficient thinning and division of the wafer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a laser beam is emitted onto the wafer to form a separation start position, then the wafer can be separated efficiently, but the laser beam components may travel through the wafer and cause damage to devices on the first surface

Engineering Contradiction:

Improvewafer separation efficiencyVSAvoiddevice damage from laser beam

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

A protective layer is formed at a first height within the wafer using a first laser beam, serving as an intermediary structure that intercepts and absorbs harmful laser beam components before they reach the devices on the first surface. This protective layer acts as a mediator that enables subsequent separation operations while protecting the devices from damage

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of substance

If the separation start position is formed at a height closer to the first surface, then material loss is reduced and chip yield increases, but the risk of device damage from laser beam increases

Engineering Contradiction:

Improvematerial loss during separationVSAvoiddevice damage risk

Core Design Contradiction:

Loss of substanceVSObject-affected harmful factors

Solution Approach 1:

The protective layer is formed in advance at a first height within the wafer before the separation start position is formed at a second height closer to the first surface. This preliminary action creates a safety barrier that enables the separation position to be optimally positioned for minimal material loss while protecting against device damage

Inventive Principle:

Principle #10Preliminary action

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

The method reduces grindstone wear, minimizes device damage, and enhances processing efficiency by allowing the separation start position to be formed closer to the device surface, resulting in reduced material loss and increased chip yield.

Implementation Method 1

positioning a first focal point of a first laser beam having a wavelength capable of penetrating the wafer at a first height within the wafer and emitting the first laser beam onto the wafer from a side on which the second surface lies while moving the first focal point and the wafer relative to each other along the first surface, thereby forming a protective layer at the first height in the wafer

Methodology Applied

Scientific EffectLaser melting and solidification: Laser Ablation

Implementation Method 2

positioning a second focal point of a second laser beam having a wavelength capable of penetrating the wafer at a second height within the wafer, the second height being more distant from the first surface than the first height, and emitting the second laser beam onto the wafer from the side on which the second surface lies while moving the second focal point and the wafer relative to each other along the first surface, thereby forming a modified layer at the second height in the wafer and forming a crack extending from the modified layer

Methodology Applied

Scientific EffectLaser-induced cracking: Laser Ablation

Data Source

PatentUS12527067B2Wafer processing method and device chip manufacturing method

Publication Date: 2026.01.13 DISCO CORP

AI summary

A wafer processing method for processing a wafer having a plurality of devices formed on a first surface thereof includes positioning a first focal point of a first laser beam at a first height and emitting the first laser beam onto the wafer from a side on which a second surface lies, thereby forming a protective layer, positioning a second focal point of a second laser beam at a second height being more distant from the first surface than the first height and emitting the second laser beam onto the wafer from the side on which the second surface lies, thereby forming a separation start position made up of a modified layer and a crack, and applying an external force to the wafer to divide the wafer at the separation start position and separating a piece including the second surface from the wafer.