Bonded Wafer Separation Using Laser-Decomposed Curable Adhesive

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Solution Overview

Problem

Current methods for separating bonded wafers with epitaxial functional layers face challenges in maintaining the integrity of the device structure portion, particularly when using curable bonding materials, as thermal processes can lead to permanent bonding and make separation difficult, resulting in a low survival rate of the device structure.

Innovation Solution

A method involving the use of a laser beam to decompose the curable bonding material and separate the support from the device structure portion, which includes irradiating the bonded wafer with a laser beam, allowing for the absorption of the laser by the curable bonding material and/or the surface of the device structure portion, thereby facilitating separation with minimal stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If thermal process is applied to create ohmic contact after removing starting substrate, then electrical contact quality is improved, but bonding strength increases making separation difficult

Engineering Contradiction:

Improveelectrical contact qualityVSAvoidbonding strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent changes the separation method from thermal/mechanical processes to laser beam irradiation. The laser beam parameters (wavelength, intensity, duration) are controlled to selectively decompose the curable bonding material without damaging the device structure, thereby achieving separation while maintaining electrical contact quality.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces traditional mechanical or thermal separation methods with laser beam irradiation. The laser energy is absorbed by the curable bonding material, causing decomposition and separation without applying mechanical stress or excessive heat that would damage the device structure or strengthen the bond further.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If traditional machining or etching method is used to remove support, then separation is achieved, but device structure portion is damaged

Engineering Contradiction:

Improveseparation processVSAvoiddevice structure integrity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces mechanical machining or chemical etching methods with laser beam irradiation. The laser energy is selectively absorbed by the curable bonding material, causing decomposition and separation without mechanical contact or harsh chemicals that would damage the device structure portion.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The laser beam acts as an intermediary that transfers energy selectively to the curable bonding material. This intermediary approach allows separation to occur through energy-mediated decomposition rather than direct mechanical or chemical action on the device structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If curable bonding material is used to firmly bond wafer, then bond strength is improved, but separation becomes difficult under thermal conditions

Engineering Contradiction:

Improvebond strengthVSAvoidseparation process

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the separation approach from thermal conditions to laser beam irradiation. The laser parameters are optimized to match the absorption characteristics of the curable bonding material, enabling decomposition and separation without the thermal constraints that would otherwise prevent separation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces thermal separation methods with laser beam irradiation. The laser energy directly decomposes the curable bonding material through photochemical or photothermal mechanisms, bypassing the need for thermal cycling that would be required for thermosetting materials and making separation feasible.

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

This method significantly increases the survival rate of the device structure portion by reducing mechanical stress during separation, compared to traditional machining or etching methods, and is suitable for wafers with epitaxial functional layers bonded to foreign substrates using thermosetting, UV-curable, or room temperature-curable materials.

Implementation Method 1

the curable bonding material and/or at least a portion of the surface of the device structure portion that comes into contact with the curable bonding material absorb(s) the laser beam to decompose the curable bonding material and/or the surface of the device structure portion

Methodology Applied

Scientific EffectLaser absorption: Absorption (EM radiation)

Implementation Method 2

by irradiating the bonded wafer with a laser beam, the curable bonding material and/or at least a portion of the surface of the device structure portion that comes into contact with the curable bonding material absorb(s) the laser beam to decompose the curable bonding material and/or the surface of the device structure portion

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS20240413264A1Method for separating a bonded wafer

Publication Date: 2024.12.12 SHIN ETSU HANDOTAI CO LTD

AI summary

The present disclosure provides a method for separating a bonded wafer, including separating a support from a bonded wafer.