Wafer Processing Using Thermoplastic Polymer Sheet Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing wafer processing methods result in chipping and degradation of device chips during dicing due to inadequate support and adhesion, leading to abnormal contact with the cutting blade and potential residue from adhesives left on the chips.
Innovation Solution
A wafer processing method using a thermoplastic polymer sheet to thermocompression bond the wafer to a rigid substrate, providing sufficient support during cutting and preventing chipping, while avoiding the use of adhesives that could leave residues on the chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a dicing tape with a soft adhesive layer is used to support the wafer, then the wafer can be transferred while keeping its form, but the device chips move during dicing causing abnormal contact with the cutting blade and chipping
Solution Approach 1:
The invention changes the physical state of the polymer sheet from unheated to heated, transforming it from a rigid state to a softened state during bonding, then back to rigid upon cooling. This parameter change enables the sheet to conform to the wafer surface during bonding while providing rigid support during dicing, resolving the contradiction between wafer form stability and device chip quality
Solution Approach 2:
The invention uses a composite structure consisting of a polymer sheet and a rigid substrate (glass or metal plate). The polymer sheet provides conformal bonding capability while the rigid substrate provides stable support during dicing. This composite material approach allows the system to simultaneously achieve wafer form stability and prevent device chip movement, eliminating chipping
2Manufacturing precision
If a substrate with rigidity is used to support the wafer during dicing, then chipping is prevented, but adhesive residues are left on the device chips after separation
Solution Approach 1:
The invention introduces a polymer sheet as an intermediary between the wafer and the rigid substrate. This intermediary layer provides the necessary adhesion during bonding while allowing clean separation after dicing, as the polymer sheet itself is removed along with the substrate. This eliminates adhesive residues on the device chips while maintaining the rigidity needed to prevent chipping during the dicing process
Solution Approach 2:
The polymer sheet is designed as a disposable component that is used once for bonding and then discarded during the separation step. This approach allows the use of a material with good bonding properties without concern for residue, as the polymer sheet is removed entirely after serving its purpose, leaving no harmful adhesive residues on the valuable device chips
3Ease of operation
If a porous ceramic chuck table is used to hold the wafer under suction, then the wafer can be positioned, but the dicing tape is sucked causing reduction of holding force on device chips
Solution Approach 1:
The polymer sheet acts as an intermediary layer between the porous ceramic chuck table and the wafer. It allows the chuck table to position the wafer through suction while preventing the dicing tape from being sucked into the pores. The polymer sheet's impermeability to gas flow blocks the harmful suction effect from reaching the dicing tape, maintaining adequate holding force on the device chips
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
Prevents chipping during dicing and eliminates the risk of adhesive residues on device chips, ensuring higher quality and integrity of the chips post-processing.
Implementation Method 1
heating the polymer sheet, and pressing the wafer toward the polymer sheet to pressure-bond the wafer through the polymer sheet to the substrate
Implementation Method 2
evacuating an enclosing environment in which the wafer is provided through the polymer sheet on the substrate
Implementation Method 3
positioning a cutting blade on the front surface of the wafer and cutting the wafer along the division lines to divide the wafer into individual device chips
Data Source
AI summary
A wafer processing method includes: a wafer providing step of providing a wafer by placing a thermoplastic polymer sheet on an upper surface of a substrate on which the wafer is supported and positioning a back surface of the wafer on an upper surface of the polymer sheet; a sheet thermocompression bonding step of evacuating an enclosing environment in which the wafer is provided through the polymer sheet on the substrate, heating the polymer sheet, and pressing the wafer toward the polymer sheet to pressure-bond the wafer through the polymer sheet to the substrate; and a dividing step of positioning a cutting blade on the front surface of the wafer and cutting the wafer along the division lines to divide the wafer into individual device chips.