Energy-Ray Curable Adhesive Sheet for Wafer Protection
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Solution Overview
Problem
In semiconductor manufacturing, especially during the DBG process, the increasing fragility of wafers due to larger diameters and thinner thicknesses makes it challenging to adhere protection sheets effectively, leading to water penetration and kerf shift issues due to poor adhesion and cohesion of existing adhesive materials on uneven chip surfaces.
Innovation Solution
An adhesive sheet with an energy-ray curable acrylic copolymer and urethane acrylate layer, incorporating dialkyl(meth)acrylamide, phenol EO modified (meth)acrylate, (meth)acryloyl morpholine, or (meth)acrylate with an aceto-acetoxyl group, providing strong adhesion and followability to uneven surfaces to prevent water penetration and kerf shift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the adhesion of a protection sheet is increased to be firmly adhered to the circuit surface of the wafer, then water penetration is prevented, but adhesion residue remains on the circuit surface after the protection sheet is stripped away
Solution Approach 1:
The patent changes the chemical parameters of the adhesive by specifying precise compositional ratios (component A at 1-30 wt%, component B at 1-50 wt%, component C at balance) to achieve optimal adhesion strength that prevents water penetration while enabling clean removal without residue. This parameter optimization resolves the contradiction between strong adhesion and residue-free removal.
Solution Approach 2:
The patent employs a composite adhesive system combining three distinct components (A, B, and C) with specific functional properties. Component A provides adhesion, component B modifies rheology and curing characteristics, and component C serves as the base resin. This composite formulation achieves both strong adhesion for water prevention and controlled removal properties.
2Reliability
If the followability to bond to the uneven circuit surface is improved, then water penetration is prevented, but the cohesion of the adhesive is lowered, causing kerf shift
Solution Approach 1:
The patent adjusts the rheological parameters of the adhesive by controlling the ratio of component B (rheology modifier) to achieve optimal balance between followability and cohesion. The specified composition ranges enable the adhesive to flow into uneven surfaces while maintaining sufficient internal strength to prevent kerf shift during processing.
Solution Approach 2:
The composite adhesive system combines components with complementary properties: component A for adhesion and followability, component B for rheological control and cohesion enhancement, and component C as the structural base. This composite approach resolves the contradiction between surface conformability and internal strength.
3Productivity
If the wafer diameter is increased and thickness is decreased to achieve higher integration, then manufacturing capacity is improved, but the wafer becomes increasingly breakable
Solution Approach 1:
The patent applies a protection sheet with optimized adhesive properties before the wafer undergoes processing steps that could cause breakage. The adhesive layer acts as a cushioning layer that distributes mechanical stresses and prevents crack propagation, enabling handling of larger, thinner wafers without increasing breakage risk.
Solution Approach 2:
The patent modifies the mechanical properties of the interface between the protection sheet and wafer surface by optimizing adhesive composition. This creates a compliant bonding layer that accommodates the reduced stiffness of thin wafers while maintaining sufficient bond strength to prevent delamination and breakage during processing.
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 sheet maintains sufficient adhesion strength and followability to prevent water penetration and kerf shift, ensuring effective protection and easy removal without residual adhesive damage during the DBG process.
Implementation Method 1
an energy-ray curable adhesive layer formed on the substrate. The energy-ray curable adhesive layer includes an energy-ray curable acrylic copolymer
Data Source
AI summary
An adhesive sheet includes a substrate and an energy-ray curable adhesive layer formed on the substrate. The energy-ray curable adhesive layer includes an energy-ray curable acrylic copolymer and a urethane acrylate. The energy-ray curable acrylic copolymer is formed by copolymerizing at least one of either a dialkyl(meth)acrylamide that has an alkyl group with carbon number of not more than 4, a phenol EO modified (meth)acrylate that has an ethylene glycol chain with a phenyl group bonded to the ethylene glycol chain, a (meth)acryloyl morpholine, or a (meth)acrylate that has an aceto-acetoxyl group, in total of 1 to 30 weight percent of all monomers to form the energy-ray curable acrylic copolymer. The energy-ray curable acrylic copolymer further includes a side chain with an unsaturated group.