Laser Surface Ablation for Fragment Removal on Sliced Substrates

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Solution Overview

Problem

During the slicing of a single crystal ingot, fragments adhere to the substrate, leading to defects and surface irregularities that existing processing methods fail to effectively remove, resulting in substrate defects.

Innovation Solution

A laser processing apparatus comprising a holder, a light source, and a moving unit that controls the position of a laser beam to remove the surface layer of the substrate, ensuring fragments are eliminated and surface defects are minimized, utilizing a controller to manage the laser processing and movement for precise removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional slicing and processing methods are used, then substrate production is achieved, but fragments adhere to the substrate surface causing defects

Engineering Contradiction:
Improvesubstrate qualityVSAvoidfragment adhesion
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The laser processing step is performed early in the substrate processing sequence, before subsequent processing steps like etching or deposition. This preliminary removal of the surface layer prevents fragments from being embedded or causing defects in later processing stages, effectively eliminating the harmful effect of fragment adhesion at the source

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces mechanical cleaning or removal methods with laser processing. The laser beam selectively removes the surface layer containing adhered fragments through ablation, providing a non-contact, precise method that avoids the limitations of mechanical approaches and effectively eliminates fragment-related defects

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If the surface layer is removed to eliminate fragments, then fragment removal is achieved, but processing time increases

Engineering Contradiction:
Improvefragment removalVSAvoidprocessing time
Core Design Contradiction:
Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The laser processing is applied selectively only to the thin surface layer where fragments are located, rather than processing the entire substrate thickness. This localized approach removes fragments effectively while minimizing the total processing time by concentrating energy only where needed

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The laser processing parameters (power, pulse duration, scanning speed) are optimized to achieve efficient material removal rates. By adjusting these parameters, the process removes the surface layer containing fragments quickly while maintaining precision, thus reducing overall processing time

Inventive Principle:
Principle #35Parameter changes

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 effectively removes adhering fragments and suppresses substrate defects by controlled laser processing, improving surface flatness and reducing the occurrence of defects, while also allowing for precise control of the surface layer removal.

Implementation Method 1

The light source is configured to oscillate a laser beam to be radiated to a first main surface of the substrate... to remove a surface layer from an entire of the first main surface of the substrate

Methodology Applied
Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS20240030021A1Laser processing apparatus and laser processing method
Publication Date: 2024.01.25 TOKYO ELECTRON LTD

AI summary

A laser processing apparatus includes a holder configured to hold a substrate obtained by slicing a single crystal ingot; a light source configured to oscillate a laser beam to be radiated to a first main surface of the substrate; a moving unit configured to move a position of a radiation point of the laser beam on the first main surface of the substrate in a state that the substrate is held by the holder; and a controller configured to control the light source and the moving unit. The controller controls the light source and the moving unit to radiate the laser beam to the first main surface of the substrate to remove a surface layer of the first main surface of the substrate, so that fragment adhering to the first main surface during the slicing of the single crystal ingot is removed.