Wafer Singulation Grooves to Prevent Hybrid Bonding Debris
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Solution Overview
Problem
In device wafer processing, debris from laser processing grooves protrudes upward from the device layer surface, causing bonding failures in hybrid bonding due to foreign matter adherence during the singulation process.
Innovation Solution
A method involving a protective film forming step, followed by laser beam application to create a mask with grooves along streets, and subsequent plasma etching using specific gases to form etching grooves that do not reach the base member surface, along with a laser processing step to form narrower grooves that divide the remaining device layer and prevent debris protrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser beam is applied to form processing grooves by removing protective film and device layer, then singulation is achieved, but debris protrudes upward from device layer surface causing bonding failures
Solution Approach 1:
The singulation process is divided into two distinct stages: first plasma etching to form initial grooves, then laser processing to complete the grooves and remove debris. This segmentation allows each process to be optimized independently, with plasma etching doing the bulk material removal and laser processing doing the final cleaning and precision work.
Solution Approach 2:
Plasma etching is performed as a preliminary action before laser processing to pre-form the grooves and remove the majority of the device layer material. This preliminary action reduces the amount of material that needs to be removed by the laser, thereby minimizing debris generation while maintaining singulation effectiveness.
2Ease of manufacture
If laser processing grooves are formed by removing device layer, then singulation is achieved, but foreign matter adherence occurs during hybrid bonding
Solution Approach 1:
The patent converts the potentially harmful laser processing debris into a beneficial situation by using plasma etching to remove the bulk of material first, leaving minimal material for laser processing. This transforms the debris problem into an advantage where the two-process approach eliminates more debris than either process could alone.
Solution Approach 2:
Plasma etching acts as an intermediary process between the protective film removal and final laser grooving. It mediates the material removal process by handling the bulk removal task, allowing the laser to focus on precision work with minimal debris generation.
3Manufacturing precision
If plasma etching is performed on device layer, then grooves are formed, but debris is generated on groove edges
Solution Approach 1:
The groove formation process is segmented into plasma etching for bulk removal and laser processing for final precision work. This segmentation allows plasma etching to be optimized for high-rate material removal while the laser completes the grooves with minimal debris.
Solution Approach 2:
The patent changes the processing parameters by switching from plasma etching to laser processing at the optimal point in groove formation. This parameter change allows the transition from a process that generates debris (plasma etching) to one that removes debris with minimal generation (laser processing).
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 effectively restrains debris from protruding from the device layer surface, ensuring successful bonding in hybrid bonding by controlling the formation and depth of etching and laser processing grooves.
Implementation Method 1
a laser beam is applied, thus removing a protective film and a device layer along streets and forming a mask
Implementation Method 2
performing plasma etching on the device layer of the device wafer by device layer gas through the mask
Implementation Method 3
applying a laser beam to the remaining portion of the device layer and forming laser processing grooves that divide the remaining portion
Data Source
AI summary
A device wafer processing method includes a protective film forming step of forming a protective film that covers a face side of a device wafer, a mask forming step of, after the protective film forming step is carried out, applying a laser beam along streets and forming, in the protective film, a mask that has grooves extending along the streets, a device layer plasma etching step of, after the mask forming step is carried out, performing plasma etching on a device layer of the device wafer by device layer gas through the mask, and a base member plasma etching step of, after the device layer plasma etching step is carried out, performing plasma etching on the base member by base member gas through the mask.