Laminate with Photochromic Release Layer for Wafer Separation
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Solution Overview
Problem
Firm adhesion between a semiconductor wafer and a support plate makes it difficult to separate the support plate without damaging the wafer, as strong adhesives used for thinning can cause damage when the support plate is removed.
Innovation Solution
A laminate comprising a light transmissive supporting member, a supported substrate with an adhesive layer, and a release layer made of inorganic material that changes properties upon light absorption, allowing for easy separation by irradiating the release layer with light, which reduces its strength and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a strong adhesive is used to firmly adhere the wafer to the support plate for thinning, then the adhesion strength is improved, but the ease of separation deteriorates as the support plate becomes difficult to remove without damaging the wafer
Solution Approach 1:
The adhesive layer is segmented into multiple functional layers: a first adhesive layer providing strong adhesion between the wafer and support plate, and a second adhesive layer with lower adhesion strength that facilitates separation. This segmentation allows the adhesive system to provide both strong bonding and easy release, resolving the contradiction between adhesion strength and ease of separation.
Solution Approach 2:
Different regions of the adhesive system have different adhesion properties. The first adhesive layer (near the wafer) has high adhesion strength to secure the wafer during processing, while the second adhesive layer (near the support plate) has low adhesion strength to enable easy separation. This local differentiation of adhesive properties resolves the contradiction between firm fixing and easy release.
2Length of moving object
If the wafer is thinned to 25-150 μm for high integration, then the chip size and thickness are reduced for better integration, but the strength of the wafer decreases making it prone to cracks and warpage
Solution Approach 1:
The support plate acts as a counterweight or reinforcement structure that compensates for the reduced strength of the thinned wafer. By adhering the thin wafer to the rigid support plate, the system provides mechanical support that prevents cracks and warpage, enabling the wafer to be handled automatically despite its reduced thickness and strength.
Solution Approach 2:
The system creates a composite structure combining the thinned wafer with a support plate and multi-layer adhesive system. This composite material approach allows the thin wafer (25-150 μm) to gain the mechanical strength and rigidity of the support plate, enabling both thinning for integration and maintenance of structural integrity for automated handling.
3Productivity
If the wafer is thinned to 150 μm or less, then the integration density is improved, but the reliability of handling deteriorates due to increased susceptibility to damage
Solution Approach 1:
The support plate provides mechanical reinforcement that counteracts the fragility of thinned wafers, enabling reliable automated handling. The support plate acts as a protective backing that prevents damage during transportation and processing, thereby maintaining high handling reliability even as wafer thickness is reduced to 150 μm or less for improved integration density.
Solution Approach 2:
The composite structure of thinned wafer plus support plate plus multi-layer adhesive creates a reliable handling system. The composite material approach allows the thin wafer to be handled with the same reliability as thicker wafers, enabling automated processing while maintaining high integration density through thinning.
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
Enables firm temporary fixing and easy separation of the support plate from the semiconductor wafer without damaging the wafer, facilitating automated handling and processing.
Implementation Method 1
a release layer which is made of an inorganic material and is provided between the supporting member and the supported substrate, the release layer having a property that changes when the release layer absorbs light coming through the supporting member
Data Source
AI summary
A laminate including a supporting member which is light transmissive; a supported substrate supported by the supporting member; an adhesive layer provided on a surface of the supported substrate which surface faces toward the supporting member; and a release layer which is made of an inorganic material and is provided between the supporting member and the supported substrate, the release layer having a property that changes when the release layer absorbs light coming through the supporting layer, and the release layer having a flat surface which faces the adhesive layer.