Thin Semiconductor Transfer Bonding for Low-Defect Thinning

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Solution Overview

Problem

Conventional methods for thinning semiconductor elements to 10 µm or less result in decreased strength and increased defect rates due to cracking, breakage, or film detachment during polishing or detachment of the support substrate.

Innovation Solution

The method involves forming an electrode protection layer and a detachment layer on the semiconductor substrate, followed by atomic diffusion joining with a support substrate in a vacuum, which enhances bonding strength and reduces defects during thinning and detachment processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the semiconductor substrate is thinned to 10 µm or less by removing the back surface substrate, then the semiconductor element can be packed at high density and performance can be increased, but the strength of the semiconductor element decreases and defects such as cracks, breakage, or film detachment occur

Engineering Contradiction:
Improvethickness of semiconductor elementVSAvoidstrength of semiconductor element
Core Design Contradiction:
Volume of moving objectVSStrength

Solution Approach 1:

A protection layer is formed on the semiconductor substrate before thinning to provide preliminary protection. This protection layer prevents cracks and breakage during the thinning process and subsequent handling, allowing the substrate to be thinned to 10 µm or less while maintaining sufficient strength

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The protection layer acts as a cushioning layer that absorbs stress and prevents crack propagation during the thinning process. By providing this protective barrier beforehand, the semiconductor element can be thinned to the required thickness without suffering from strength degradation and defect formation

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Volume of moving object

If the semiconductor substrate is thinned to 10 µm or less, then high-density packing and downsizing can be achieved, but the defect rate increases due to cracking, breakage, or film detachment during polishing and detachment

Engineering Contradiction:
Improvethickness of semiconductor elementVSAvoiddefect rate of semiconductor element
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The protection layer is formed in advance before thinning to prevent defects during subsequent processing steps. This preliminary protective measure ensures that cracks, breakage, and film detachment do not occur during polishing and detachment operations, maintaining low defect rates even when the substrate is thinned to 10 µm or less

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The protection layer serves as an intermediary between the semiconductor substrate and the external environment during thinning and handling. This intermediate layer protects the fragile thinned substrate from mechanical damage and stress, thereby reducing the defect rate during polishing and detachment processes

Inventive Principle:
Principle #24Intermediary (Mediator)

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 significantly reduces defects such as cracking, detachment, or breakage during the thinning process, maintaining mechanical strength and achieving a low defect rate in the semiconductor element.

Implementation Method 1

a metal thin film 6 is formed on each of an electrode protection layer 3 on the circuit element substrate 7 and the support substrate 8 in vacuum, and the metal thin films 6 are attached by an atomic diffusion joining method to join the circuit element substrate 7 and the support substrate 8

Methodology Applied
Scientific EffectAtomic diffusion joining: Diffusion Welding

Data Source

PatentEP4138116B1Method for manufacturing semiconductor element
Publication Date: 2024.03.13 MITSUBISHI ELECTRIC CORP
  • EP4138116B1 patent drawingFigure 1
  • EP4138116B1 patent drawingFigure 2
  • EP4138116B1 patent drawingFigure 3~6

AI summary

It is an object of the present invention to provide a method of manufacturing a thin semiconductor element having a low defect rate. A method of manufacturing a semiconductor element according to the present invention includes: preparing a circuit element substrate (7) including a semiconductor substrate (1) and a circuit element (2) on the semiconductor substrate (1); forming an electrode protection layer (3) on the circuit element (2); preparing a support substrate (8); forming a metal thin film (6) on the electrode protection layer (3) of the circuit element substrate (7) and the support substrate (8) in vacuum; attaching the metal thin film (6) of the circuit element substrate and the metal thin film (6) of the support substrate by an atomic diffusion joining method, thereby joining the circuit element substrate (7) and the support substrate (8); removing the semiconductor substrate (1) by polishing to expose the circuit element (2); joining a transfer substrate (10) to an exposed surface of the circuit element (2); and detaching the support substrate (8) from the circuit element (2) after joining the transfer substrate (10).