Wafer Processing Using Adhesive-Free Polyester Sheet
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Solution Overview
Problem
The existing wafer processing methods using adhesive tapes for dividing wafers into device chips often result in the adhesive layer melting and adhering to the chips, leading to quality degradation due to the adherence of the adhesive layer on the device chips.
Innovation Solution
A wafer processing method utilizing a polyester sheet without an adhesive layer for thermocompression bonding with the wafer and ring frame, allowing the laser beam to form shield tunnels for division, and then using air to lift and pick up the device chips, thereby preventing adhesive layer adherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an adhesive tape is used to hold the wafer during laser processing, then the wafer can be securely fixed and processed, but the adhesive layer melts and adheres to the device chips, degrading their quality
Solution Approach 1:
The invention extracts and removes the adhesive layer from the tape structure. The patent uses a tape consisting only of a base layer without any adhesive layer, thereby eliminating the source of the harmful adhesion to chip surfaces while maintaining the holding function through alternative means
Solution Approach 2:
The invention introduces a release paper as an intermediary layer between the tape base layer and the wafer. This release paper serves as a mediator that allows the wafer to be held during processing but can be easily separated after processing without leaving adhesive residue on the chips
2Ease of operation
If ultraviolet light is applied to reduce adhesive tape adhesion for chip pickup, then chips can be released from the tape, but the previously melted adhesive layer remains on the chip surfaces, still degrading quality
Solution Approach 1:
The invention extracts the adhesive layer entirely from the system by using a tape with only a base layer and no adhesive layer. This eliminates the need for ultraviolet light treatment and prevents any adhesive residue from remaining on chip surfaces
Solution Approach 2:
The release paper is designed to self-release from the base layer after laser processing without requiring additional ultraviolet light treatment. The release paper naturally detaches, allowing easy chip pickup while leaving clean chip surfaces
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
This method effectively prevents the adhesive layer from adhering to the device chips, maintaining their quality by eliminating the issue of adhesive layer adherence during the division process.
Implementation Method 1
a laser beam is applied inside the wafer in order to form shield tunnels which serves as a division start point, inside the wafer
Implementation Method 2
heating the polyester sheet as applying a pressure to the polyester sheet after performing the polyester sheet providing step, thereby uniting the wafer and the ring frame through the polyester sheet by thermocompression bonding
Data Source
AI summary
A wafer processing method includes a polyester sheet providing step of positioning a wafer in an inside opening of a ring frame and providing a polyester sheet on a back side or a front side of the wafer and on a back side of the ring frame, a uniting step of heating the polyester sheet as applying a pressure to the polyester sheet to thereby unite the wafer and the ring frame through the polyester sheet by thermocompression bonding, a dividing step of applying a laser beam to the wafer to form shield tunnels in the wafer, thereby dividing the wafer into individual device chips, and a pickup step of blowing air to each device chip from the polyester sheet side to push up each device chip through the polyester sheet and picking up each device chip from the polyester sheet.