Adhesive Sheet for Semiconductor Wafer Backgrinding
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Solution Overview
Problem
During the backgrinding of semiconductor wafers, adhesive sheets used to prevent damage and contamination often cause damage to thinner wafers due to increased adhesive strength over time, leading to residual glue and contamination of the circuit-forming surface.
Innovation Solution
An adhesive sheet with a substrate of ethylene/vinyl acetate copolymer and an adhesive layer containing a (meth)acrylate ester copolymer, a cross-linker, and a silicone compound, which reduces infiltration, maintains stable adhesive strength, and minimizes residual glue, thereby reducing wafer damage and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an adhesive sheet is used to prevent damage and contamination during backgrinding, then the semiconductor wafer is protected from damage and contamination, but the adhesive strength increases over time causing damage to thinner wafers and residual glue on the circuit-forming surface
Solution Approach 1:
The patent modifies the adhesive composition by incorporating a silicone compound with specific functional groups (epoxy, carboxyl, hydroxyl, amino, or vinyl) that can form cross-linking structures. This chemical parameter change enables the adhesive to maintain stable bonding strength over time without excessive increase, resolving the contradiction between providing adequate protection and avoiding damage to thin wafers during peeling
Solution Approach 2:
The adhesive sheet combines a substrate made of ethylene/vinyl acetate copolymer with an adhesive layer containing (meth)acrylate ester copolymer and silicone compound. This composite structure leverages the protective properties of the substrate while the silicone-modified adhesive provides controlled bonding characteristics that prevent both insufficient protection and excessive adhesion strength
2Strength
If the adhesive strength increases over time, then the attachment to the semiconductor wafer becomes tighter, but the semiconductor wafer is damaged during peeling
Solution Approach 1:
The silicone compound content (0.05 to 5 parts by mass per 100 parts of (meth)acrylate ester copolymer) and its functional group composition are optimized to control the adhesive's curing characteristics. This parameter optimization ensures the adhesive achieves sufficient bonding strength while maintaining flexibility and reducing stress concentration during peeling, thereby preventing wafer damage
Solution Approach 2:
The silicone compound acts as an intermediary that modifies the adhesive's interaction with the wafer surface. Its functional groups create a bonding mechanism that is strong enough to prevent contamination but gentle enough to allow clean peeling without damaging thin wafers, mediating between the need for tight attachment and safe removal
3Object-affected harmful factors
If washing water infiltrates the circuit-forming surface, then contamination occurs on the semiconductor wafer, but using an adhesive sheet with high adhesive strength prevents infiltration
Solution Approach 1:
The adhesive composition parameters, particularly the silicone compound content and functional group types, are adjusted to achieve optimal bonding strength that prevents water infiltration during backgrinding while avoiding excessive strength that would cause damage during peeling. The ethylene/vinyl acetate copolymer substrate also contributes to water resistance
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 effectively prevents wafer damage and contamination by reducing infiltration, maintaining consistent thickness, and minimizing adhesive strength increase over time, even for thin wafers, ensuring reliable backgrinding without significant residual glue.
Implementation Method 1
an adhesive sheet including a substrate and an adhesive layer disposed on the substrate... the sheet having an adhesive layer used for pressure-sensitive bonding
Implementation Method 2
the adhesive layer contains 100 parts by mass of a (meth)acrylate ester copolymer, 1 to 10 parts by mass of a cross-linker
Implementation Method 3
0.05 to 5 parts by mass of a silicone compound... the adhesive strength has a small increase rate over time... after peeling of the adhesive sheet, the circuit-forming surface of the semiconductor wafer has a little residual glue
Data Source
AI summary
After an adhesive sheet is pasted on a semiconductor wafer, an adhesive of the sheet increases tight attachment to the semiconductor wafer because wetting spreads over time. Due to this, at the time of peeling the adhesive sheet from the ground semiconductor wafer, the semiconductor wafer used to be damaged. This phenomenon is likely to occur for a thinner semiconductor wafer. The present invention resides in an adhesive sheet including a substrate and an adhesive layer disposed on the substrate. The substrate is formed of an ethylene/vinyl acetate copolymer having a vinyl acetate content of 10% by mass or less. The adhesive layer contains 100 parts by mass of a (meth)acrylate ester copolymer, 1 to 10 parts by mass of a cross-linker, 0.05 to 5 parts by mass of a silicone compound. The (meth)acrylate ester copolymer is formed of a copolymer produced by polymerizing a (meth)acrylate ester monomer and a functional-group-containing monomer.