Wafer Processing Using Polyolefin Sheet Bonding
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Solution Overview
Problem
The existing wafer processing methods generate cutting dust from adhesive tapes, which adheres to device chips, leading to quality degradation during the cutting process.
Innovation Solution
A wafer processing method using a polyolefin sheet without an adhesive layer for thermocompression bonding with the wafer and ring frame, allowing for clean cutting and easy removal of cutting dust, and facilitating the separation of device chips with reduced load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive tape is used to bond wafer to ring frame, then wafer can be held and processed, but cutting dust from adhesive layer adheres to device chips causing quality degradation
Solution Approach 1:
The patent removes the adhesive layer from the bonding structure by replacing adhesive tape with a double-sided tape-less bonding method. The wafer is bonded to the ring frame using mechanical clamping force from the ring frame structure itself, eliminating the source of adhesive cutting dust that would contaminate device chips during dicing.
Solution Approach 2:
The patent introduces a double-sided tape as an intermediary bonding layer between the wafer and ring frame. This double-sided tape is specifically designed to be cut along with the wafer without generating harmful dust, serving as a clean intermediary that maintains bonding strength while preventing contamination.
2Reliability
If cutting blade depth is increased to ensure complete wafer division, then division reliability improves, but adhesive layer cutting dust generation increases
Solution Approach 1:
The patent eliminates the adhesive layer that generates harmful cutting dust by removing traditional adhesive tape and replacing it with a double-sided tape bonding method. This allows the cutting blade to cut through the wafer with minimal depth below the wafer surface, ensuring complete division without cutting through thick adhesive layers that would generate excessive dust.
Solution Approach 2:
The patent changes the bonding method parameters from using thick adhesive tape to using thin double-sided tape, which alters the cutting depth requirements. The cutting blade can now operate at optimal depth to ensure reliable wafer division while minimizing dust generation from the reduced adhesive layer thickness.
3Ease of manufacture
If conventional adhesive tape is used, then bonding process is simple, but cleaning step becomes difficult and time-consuming
Solution Approach 1:
The patent removes the problematic adhesive layer from conventional adhesive tape by implementing a double-sided tape bonding system. This extraction of the harmful adhesive component eliminates the need for extensive cleaning steps, as the double-sided tape material is designed to be cleanly removed or does not generate adhering dust particles during cutting.
Solution Approach 2:
The patent employs a disposable double-sided tape bonding solution where the bonding material is designed for single-use and easy removal. The double-sided tape is sacrificed during the cutting process, and its material properties ensure it does not leave residue requiring time-consuming cleaning, making the process both simple and clean.
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 cutting dust adherence to device chips, thereby suppressing quality degradation and enabling reliable cleaning and efficient chip separation.
Implementation Method 1
heating the polyolefin sheet as applying a pressure to the polyolefin sheet after performing the polyolefin sheet providing step, thereby uniting the wafer and the ring frame through the polyolefin sheet by thermocompression bonding
Implementation Method 2
cooling the polyolefin sheet in each of the plurality of separate regions corresponding to each device chip, pushing up each device chip through the polyolefin sheet
Data Source
AI summary
A wafer processing method includes a polyolefin sheet providing step of positioning a wafer in an inside opening of a ring frame and providing a polyolefin sheet on a back side of the wafer and on a back side of the ring frame, a uniting step of heating the polyolefin sheet as applying a pressure to the polyolefin sheet to thereby unite the wafer and the ring frame through the polyolefin 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 cooling the polyolefin sheet, pushing up each device chip through the polyolefin sheet, and then picking up each device chip from the polyolefin sheet.