Wafer Dicing Sequence With Reverse-Side Grooves and In-Place Laser Split
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Solution Overview
Problem
In device wafer processing, there is a challenge in reducing foreign matter adherence to the face side of wafers during hybrid bonding, which can lead to bonding failures, and existing methods like laser processing can cause breakage and poor productivity due to limitations in cutting depth and chipping/cracking issues.
Innovation Solution
A method and apparatus that involve holding the device wafer on a table, cutting with a blade from the reverse side to form grooves that do not reach the functional layer, followed by laser processing along these grooves without unloading the wafer, using a liquid layer for laser beam application to reduce adherence and breakage risks, and additional steps like water-soluble resin coating and tape affixing for enhanced cleaning and handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser processing is applied to the same street multiple times for full cutting, then the wafer can be divided into individual devices, but productivity deteriorates due to repeated processing
Solution Approach 1:
The cutting process is divided into two stages: first, a cutting blade forms grooves that segment the wafer structure; second, laser processing completes the division along these pre-formed grooves. This segmentation of the cutting process allows the laser to follow predetermined paths rather than creating grooves from scratch, reducing processing time and improving productivity while maintaining cutting completeness.
Solution Approach 2:
The cutting blade performs preliminary action by forming grooves in the wafer before laser processing occurs. These pre-formed grooves serve as guides for the laser beam, allowing the laser to complete the cutting more efficiently by following the established paths rather than creating grooves de novo, thereby improving productivity without sacrificing cutting precision.
2Productivity
If a cutting blade is used to divide the wafer, then productivity improves, but chipping and cracking occur on the face side
Solution Approach 1:
Instead of cutting from the face side where devices are located, the cutting blade cuts from the reverse side of the wafer. This inversion of the cutting direction allows the blade to form grooves without directly contacting the face side, preventing chipping and cracking while maintaining processing speed. The laser then completes the cutting from the reverse side as well, further protecting the face side integrity.
Solution Approach 2:
The cutting blade acts as an intermediary that prepares the wafer structure by forming grooves from the reverse side without directly affecting the face side quality. This intermediary action creates a pathway that guides subsequent laser processing, allowing the final cut to be made with precision while protecting the face side from mechanical damage.
3Adaptability or versatility
If the wafer is unloaded between cutting and laser processing, then different processing can be performed, but breakage risk increases during attachment and detachment
Solution Approach 1:
The cutting and laser processing operations are merged into a single continuous process where the wafer remains loaded in the same apparatus. The cutting blade forms grooves, and then the laser beam follows these grooves to complete the cutting, all without unloading the wafer. This merging eliminates the risk of breakage during transfer while maintaining processing flexibility through the coordinated sequence of operations.
Solution Approach 2:
The useful action of cutting continues uninterrupted from the blade forming grooves to the laser completing the division. The wafer remains in place throughout this continuous process, eliminating idle transfer time and reducing breakage risk. The seamless transition between cutting stages maintains productivity while ensuring wafer integrity through continuous support.
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 effectively reduces foreign matter adherence and breakage risks by continuous laser processing on the held wafer, improving productivity and bonding success rates.
Implementation Method 1
a laser processing step of applying a laser beam having a wavelength absorbable by the device wafer to the device wafer from the reverse side of the device wafer along the cutting grooves and dividing the device wafer into individual devices
Implementation Method 2
applying a laser beam having a wavelength absorbable by the device wafer
Implementation Method 3
a liquid layer is formed on the reverse side of the device wafer, and the laser beam is applied to the device wafer through the liquid layer
Data Source
AI summary
A device wafer processing method includes a holding step of holding a face side of a device wafer by a holding table, a cutting step of cutting the device wafer by a cutting blade from a reverse side of the device wafer along streets and forming cutting grooves that do not reach a functional layer, and a laser processing step of applying a laser beam having a wavelength absorbable by the device wafer to the device wafer from the reverse side of the device wafer along the cutting grooves and dividing the device wafer into individual devices. The laser processing step is carried out in a state in which the device wafer is continuously held on the holding table without being unloaded from the holding table, after the cutting step is carried out.