Patternable Adhesive for 3D Semiconductor Stacking
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Solution Overview
Problem
Current patternable adhesives for semiconductor packages lack sufficient heat resistance, patternability, and dimensional stability, especially when used in through-silicon-via (TSV) techniques, which require adhesives that are both adhesive and capable of high-temperature bonding while maintaining structural integrity.
Innovation Solution
A patternable adhesive composition comprising an alkali soluble resin with an alkali soluble group and acryloyl group, a radically polymerizable compound, a thermosettable compound, and a photo-radical initiator, which can be patterned and adhered at high temperatures, providing excellent heat resistance and dimensional stability, and is developed using a process involving UV exposure and alkali treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional patternable adhesives are used for TSV technique, then basic adhesion is achieved, but heat resistance and dimensional stability are insufficient
Solution Approach 1:
The adhesive composition combines multiple resin components (alkali-soluble resin with carboxyl groups, radically polymerizable compound, and thermosettable compound) to create a composite material that simultaneously achieves high heat resistance, dimensional stability, and adhesion. The synergistic interaction between different resin types resolves the contradiction between heat resistance and dimensional stability.
Solution Approach 2:
The patent optimizes specific parameters including the glass transition temperature (Tg) of the alkali-soluble resin (100°C or higher), acid value (30-100 mg KOH/g), and molecular weight (5-30 kDa) to achieve the desired balance between heat resistance and dimensional stability. These parameter adjustments directly address the technical contradiction.
2Reliability
If high Tg resin is used to improve heat resistance, then heat resistance improves, but patternability deteriorates
Solution Approach 1:
The adhesive composition exhibits different properties in exposed and unexposed regions after photolithography. The unexposed portions remain alkali-soluble for pattern formation, while exposed portions undergo crosslinking for heat resistance. This local differentiation resolves the contradiction between heat resistance and patternability.
Solution Approach 2:
The photolithography process is performed before final curing to pre-establish the pattern structure. This preliminary action allows the adhesive to be patterned when it has good solubility, while the subsequent thermal curing provides the heat resistance needed for high-temperature processing.
3Strength
If high adhesion at high temperature is achieved, then bonding strength improves, but thickness variation increases
Solution Approach 1:
The patent controls the glass transition temperature (Tg) at 100°C or higher and optimizes the acid value and molecular weight parameters to maintain dimensional stability during high-temperature curing. This prevents excessive thickness variation while achieving strong adhesion at elevated temperatures.
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 composition exhibits high shear bond strength, reliable bonding between semiconductor dies, and minimal thickness variation, enabling efficient 3D stacking and reliable thermal curing, while also being environmentally friendly due to the use of an aqueous alkali developing solution.
Implementation Method 1
at least one photo-radical initiator D
Implementation Method 2
the patternable adhesive composition has a total acid value of about 40 to about 60 mgKOH/g and a film of the patternable adhesive composition has a dissolution rate of about 0.1 micrometer per second (μm/sec) or more when contacted with a 2.38 percent by weight of a tetramethylammonium hydroxide ('TMAH') developing solution
Implementation Method 3
providing excellent heat resistance and dimensional stability, and is developed using a process involving UV exposure and alkali treatment
Data Source
AI summary
A patternable adhesive composition including at least one alkali soluble resin including an alkali soluble group and an acryloyl group, at least one radically polymerizable compound, at least one thermosettable compound, and at least one photo-radical initiator.