Wafer Division via Laser Modified Layers and Chemical Etching

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Solution Overview

Problem

The existing wafer dividing method using laser-induced modified layers results in fine particles being generated, which can stick to device surfaces, reducing quality and die strength due to residual modified layers on side surfaces.

Innovation Solution

A wafer dividing method that forms modified layers inside the wafer using a laser beam with a transmission wavelength and then employs an etching step with gas or liquid to erode these layers, preventing particle generation and residual strength reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If external force is applied to break the wafer along modified layers, then wafer division is achieved, but fine particles are generated and stick to device surfaces reducing quality

Engineering Contradiction:

Improvewafer division efficiencyVSAvoidfine particle contamination on device surfaces

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical breaking method with a chemical etching method. Instead of applying external force to break the wafer along modified layers, an etching solution is used to chemically remove the modified layers, thereby dividing the wafer without generating fine particles that would contaminate device surfaces.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the method parameter from mechanical force to chemical etching. By transforming the division mechanism from physical breaking to chemical removal, the harmful effect of fine particle generation is eliminated while maintaining effective wafer division.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If external force is applied to break the wafer along modified layers, then wafer division is achieved, but modified layers remain on side surfaces reducing die strength

Engineering Contradiction:

Improvewafer division efficiencyVSAvoiddie strength

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The patent replaces mechanical breaking with chemical etching to remove modified layers completely. The etching solution penetrates and removes the modified layers along the division lines, preventing their retention on device side surfaces and thereby maintaining die strength.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and removes the modified layers from the wafer structure using chemical etching. By completely removing the modified layers rather than leaving them on the side surfaces, the die strength is preserved while achieving effective wafer division.

Inventive Principle:

Principle #2Taking out (Extraction)

3Manufacturing precision

If laser beam is applied to form modified layers inside the wafer, then division lines are created, but modified layers must be subsequently removed to prevent quality reduction

Engineering Contradiction:

Improvedivision line precisionVSAvoidquality reduction due to modified layer remnants

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces mechanical removal methods with chemical etching to remove modified layers. The etching solution selectively removes the modified layers created by the laser beam, achieving complete removal without damaging the precise division lines and preventing quality reduction from residual layers.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Prevents fine particles from adhering to device surfaces, maintaining quality and die strength by removing modified layers through etching, thereby ensuring high-quality device separation.

Implementation Method 1

applying a laser beam having a transmission wavelength to the wafer in the condition where the focal point of the laser beam is set inside the wafer at the positions corresponding to the division lines, thereby forming a plurality of modified layers inside the wafer along the division lines

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 2

supplying an etching gas or an etching liquid to the wafer to erode the modified layers, thereby dividing the wafer into the individual devices

Methodology Applied

Scientific EffectChemical etching: Chemical Bonding

Data Source

PatentUS8673743B2Wafer dividing method

Publication Date: 2014.03.18 DISCO CORP

AI summary

A wafer is divided by setting the focal point of a laser beam inside the wafer at positions corresponding to division lines, thereby forming modified layers inside the wafer along the division lines. Each modified layer has a thickness ranging from the vicinity of the front side of the wafer to the vicinity of the back side of the wafer. An etching gas or an etching liquid is supplied to the wafer to erode the modified layers, thereby dividing the wafer into individual devices. The modified layers are not crushed, so fine particles are not generated in dividing the wafer. Accordingly, fine particles do not stick to the surface of each device and cause a reduction in quality. Further, since the modified layers are removed by etching, it is possible to prevent a reduction in die strength of each device due to the remainder of the modified layers.