Wafer Processing Using Adhesive-Free Polyester Sheet
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Solution Overview
Problem
The existing wafer processing methods generate cutting dust from adhesive layers during wafer cutting, which adheres to device chips and degrades their quality, making it difficult to remove and leading to quality issues in device chips.
Innovation Solution
A wafer processing method using a polyester sheet without an adhesive layer for thermocompression bonding with the wafer and ring frame, allowing for clean cutting and easy removal of cutting dust, where the polyester sheet is heated and applied under pressure to form a frame unit, and air is used to push up and pick up device chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive tape is used to hold the wafer during cutting, then the wafer can be securely held and processed, but cutting dust from the adhesive layer adheres to device chips and degrades quality
Solution Approach 1:
The invention extracts and removes the adhesive layer from the holding structure. Instead of using adhesive tape that generates harmful cutting dust, the patent uses a double-sided tape-free holding method where the wafer is held by mechanical means (chuck table with suction or mechanical clamps) that do not produce adhesive dust during cutting.
Solution Approach 2:
The invention introduces an intermediary holding mechanism (chuck table with suction cups or mechanical clamps) that mediates between the wafer and the cutting blade. This intermediary holds the wafer securely without using adhesive materials, thus preventing cutting dust adhesion while maintaining holding strength.
2Reliability
If adhesive layer is present during cutting, then wafer can be held firmly, but cleaning becomes difficult and device quality degrades
Solution Approach 1:
The invention extracts the adhesive layer from the process, eliminating the source of cleaning difficulties. By using mechanical or suction-based holding methods without adhesive tape, the wafer and device chips remain free of adhesive residues, making cleaning straightforward and maintaining high device quality.
Solution Approach 2:
The invention segments the holding function from the adhesive material. Instead of using a unified adhesive tape solution, the patent separates the holding function into distinct mechanical or suction-based components that do not leave residues, enabling easier cleaning and quality maintenance.
3Productivity
If adhesive tape is used for wafer holding, then processing can be performed, but cutting dust adheres to devices and requires extensive cleaning
Solution Approach 1:
The invention extracts the adhesive layer that causes cleaning time loss. By using adhesive-free holding methods, the cutting process generates no adhesive dust, eliminating or significantly reducing the cleaning step and associated time loss while maintaining processing efficiency.
Solution Approach 2:
The invention converts the potential harm of adhesive dust generation into a benefit by using holding methods that produce no dust at all. The adhesive-free approach transforms a problematic process into a clean, efficient operation where cutting dust does not adhere to devices, reducing or eliminating cleaning requirements.
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 prevents cutting dust from adhering to device chips, reducing the risk of quality degradation and facilitating reliable cleaning, as the polyester sheet's absence of an adhesive layer ensures that cutting dust is diffused and removed effectively.
Implementation Method 1
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
Implementation Method 2
blowing out air from the polyester sheet side to push up each device chip and picking up the device chip from the polyester sheet
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 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 cutting the wafer by using a cutting apparatus to thereby divide the wafer into individual device chips, and a pickup step of blowing out air to push up each device chip and picking up each device chip from the polyester sheet.