Wafer Dicing Tape Adhesion Detection via Optical Imaging
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Solution Overview
Problem
In wafer processing, poor adhesion of die attach film (DAF) to chips can lead to bubbles between the DAF and the wafer, causing inefficient chip mounting and wastage, as conventional methods rely on post-mounting checks for adhesion issues.
Innovation Solution
A method involving imaging the wafer through a dicing or expansion tape with a UV-curable adhesive layer to detect and store positions of poor adhesion, followed by selective separation and pickup of chips with well-adhered DAF, ensuring only properly bonded chips are mounted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional post-mounting adhesion checks are used, then chip mounting can proceed with simple process, but chips with poor adhesion are mounted causing wastage and reduced efficiency
Solution Approach 1:
The patent applies preliminary imaging and detection of poor adhesion positions before chip mounting. The DAF adhesion state is checked in advance using optical imaging through the tape, and chips with poor adhesion are identified and excluded before the mounting process begins, preventing wastage while maintaining efficient production
Solution Approach 2:
The patent implements a feedback mechanism where the imaging system detects poor adhesion positions and provides this information back to the pickup system. The pickup system then uses this feedback information to selectively pick only chips with good adhesion, creating a closed-loop quality control system that improves both reliability and productivity
2Reliability
If imaging through dicing tape is performed to detect poor adhesion, then adhesion quality can be assessed beforehand, but process complexity increases
Solution Approach 1:
The patent uses the transparent dicing tape itself as an intermediary medium for imaging. By imaging through the tape rather than requiring separate transparent windows or complex sample preparation, the system leverages the existing tape structure to enable adhesion detection, reducing overall system complexity while maintaining reliability
Solution Approach 2:
The patent replaces complex mechanical adhesion testing methods with optical imaging detection. Instead of using mechanical probes or complex physical tests to check adhesion, the system uses non-contact optical imaging through the tape to detect poor adhesion positions, simplifying the detection system while improving reliability
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 approach eliminates the risk of mounting chips with poor adhesion, improving working efficiency by preventing wastage and ensuring reliable chip bonding.
Implementation Method 1
an adhesive layer curable by the application of ultraviolet light... applying ultraviolet light to this tape to thereby cure the adhesive layer
Implementation Method 2
imaging the wafer through the dicing tape to obtain an image of the wafer after performing the tape attaching step, detecting the positions of poor adhesion where the DAF does not adhere to the wafer, from the image
Data Source
AI summary
Disclosed herein is a wafer processing method including the steps of attaching a dicing tape to the back side of a wafer, the dicing tape being composed of a base tape, a DAF, and an adhesive layer for uniting the base tape and the DAF, imaging the wafer through the dicing tape to obtain an image of the wafer, detecting the positions of poor adhesion of the DAF from the image, storing the positions of poor adhesion detected above, dividing the wafer and the DAF into individual chips each having the DAF, curing the adhesive layer of the dicing tape by the application of ultraviolet light, selectively separating the chips with the DAF well adhered, at the boundary between the adhesive layer and the DAF according to the positions of poor adhesion stored above, and then picking up the chips with the DAF well adhered.