Polysiloxane Temporary Adhesive for Void-Free Wafer Bonding
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Solution Overview
Problem
Existing temporary adhesives for semiconductor wafers fail to provide adequate stress resistance during polishing, easy detachment after polishing, and prevent void formation between the support and wafer, while maintaining heat resistance and spin coating properties.
Innovation Solution
A temporary adhesive comprising a polysiloxane component cured by hydrosilylation reaction, a polymerization inhibitor with a 5% mass decrease temperature of 80°C or higher, and a solvent, which inhibits premature curing and allows easy separation and removal after polishing, ensuring heat resistance and void-free attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a temporary adhesive is designed to have high adhesion force during polishing, then stress resistance during polishing is improved, but detachment force during separation becomes too high making easy detachment difficult
Solution Approach 1:
The adhesive system is segmented into two functional layers: a lower adhesive layer providing strong bonding to the support, and an upper separation layer with weak adhesion to the wafer. This segmentation allows the lower layer to provide high stress resistance during polishing while the upper layer enables easy detachment after polishing, resolving the contradiction between strong adhesion and easy separation.
Solution Approach 2:
Different regions of the adhesive system are assigned different adhesive properties: the lower layer near the support has high adhesion force for stress resistance, while the upper layer near the wafer has low adhesion force for easy detachment. This local differentiation of quality allows simultaneous achievement of both high stress resistance and easy separation.
2Ease of manufacture
If a polymerization inhibitor with low boiling point is used, then spin coating properties are improved, but heat resistance during processing deteriorates due to premature curing
Solution Approach 1:
The polymerization inhibitor is selected with specific parameter ranges: boiling point of 80-180°C and 5% mass decrease temperature of 100-180°C. This parameter optimization allows the inhibitor to remain effective during spin coating while maintaining stability during subsequent heating processes, preventing premature curing and ensuring heat resistance.
Solution Approach 2:
The adhesive composition is formulated as a composite system combining polysiloxane base resin, polymerization inhibitor, and solvent in specific ratios. This composite formulation synergistically achieves both good spin coating properties (through appropriate solvent and inhibitor selection) and heat resistance (through stable polysiloxane matrix and high-temperature-stable inhibitor).
3Manufacturing precision
If the adhesive cures completely before attachment, then manufacturing precision is improved, but void formation occurs preventing proper attachment
Solution Approach 1:
The adhesive is designed to undergo preliminary solvent removal and partial curing after coating but before wafer attachment. This preliminary action prepares the adhesive layer for optimal bonding while preventing complete curing that would cause void formation. The controlled timing of curing stages ensures both manufacturing precision and attachment quality.
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 adhesive maintains excellent spin coating properties and heat resistance, enabling easy separation and void-free attachment, thus facilitating three-dimensional wafer integration with minimal deformation.
Implementation Method 1
a component (A) that is cured by a hydrosilylation reaction
Implementation Method 2
a polymerization inhibitor (B) having a 5% mass decrease temperature of 80° C. or higher
Implementation Method 3
a solvent (C)
Data Source
AI summary
A temporary adhesive without the formation of voids between a support and a wafer. A temporary adhesive for separatably attaching a support to a circuit side of a wafer to process a rear surface of the wafer, the temporary adhesive including a component (A) that is cured by a hydrosilylation reaction; a polymerization inhibitor (B) having a 5% mass decrease temperature of 80° C. or higher as measured using a Tg-DTA; and a solvent (C). The component (A) may include a polysiloxane (A1) including a polyorganosiloxane (a1) containing a C1-10 alkyl group and a C2-10 alkenyl group, and a polyorganosiloxane (a2) containing a C1-10 alkyl group and a hydrogen atom; and a platinum group metal-based catalyst (A2). The polymerization inhibitor (B) may be a compound of formula (1):(wherein R7 and R8 are each a C6-40 aryl group, or a combination of a C1-10 alkyl group and a C6-40 aryl group).