Wafer Processing Using Non-Adhesive Polyester Sheet
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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 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, and facilitating the pickup of device chips with reduced load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive tape is used to bond the wafer to the ring frame, then the wafer can be held and processed, but cutting dust from the adhesive layer adheres to the device chips causing quality degradation
Solution Approach 1:
The invention extracts and removes the adhesive layer from the bonding system. By using a double-sided adhesive tape where only the lower surface (contacting the chuck table) has adhesive properties and the upper surface (contacting the wafer) is non-adhesive, the source of cutting dust adhesion is eliminated while maintaining wafer holding capability through mechanical friction and vacuum suction.
Solution Approach 2:
The invention introduces a double-sided adhesive tape as an intermediary bonding element that differentiates its adhesive properties between its two surfaces. The lower surface provides adhesion to the chuck table for secure holding, while the upper non-adhesive surface prevents cutting dust adhesion to the wafer, thus mediating between the conflicting requirements of secure holding and clean surface.
2Manufacturing precision
If the cutting blade cuts deep enough to reliably divide the wafer, then the wafer is properly divided, but the adhesive layer is also cut generating additional cutting dust
Solution Approach 1:
The invention extracts the adhesive layer from the wafer bonding system, eliminating the source of additional cutting dust. By using a non-adhesive upper surface of the tape, the cutting blade only generates dust from the wafer material itself, not from the adhesive layer, thus reducing total dust generation while maintaining cutting depth for proper wafer division.
3Ease of operation
If adhesive tape is used to bond device chips, then chips can be held for processing, but cleaning cutting dust from device chips becomes difficult
Solution Approach 1:
The invention extracts the adhesive layer from the chip bonding interface. By using a non-adhesive upper surface, cutting dust does not adhere to the device chips, eliminating the cleaning difficulty. The chips remain easily handleable through the non-adhesive tape's mechanical holding capability without the complicating factor of dust adhesion.
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 adherence of cutting dust to device chips, thereby suppressing quality degradation and ensuring reliable cleaning and handling of device chips.
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
An annular abrasive portion is provided around the outer circumference of the cutting blade, so as to cut the wafer
Implementation Method 3
applying ultraviolet light to the adhesive tape to thereby reduce the adhesion of the adhesive tape
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 heating the polyester sheet, pushing up each device chip through the polyester sheet, and then picking up each device chip from the polyester sheet.