Bonded Wafer Edge Detection Using Through-Hole Imaging
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Solution Overview
Problem
Accurately detecting the outer peripheral edge position of a bonded wafer is challenging due to variations in the types, thicknesses, and sizes of components, as well as the positional relationship between the wafer and support plate, leading to potential errors in positioning the cutting blade for edge trimming.
Innovation Solution
A method involving a holding unit with a chuck table and irradiating means to illuminate the wafer's edge, capturing images through a through hole, and using imaging means to detect the edge position, allowing for precise positioning of a cutting blade to cut off an annular portion from the bonded wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the wafer is bonded to the support plate with the adhesive member sticking out, then the handleability of thin wafers is improved and warping is prevented, but the outer peripheral edge position of the bonded wafer becomes difficult to detect accurately
Solution Approach 1:
The patent divides the imaging process into two distinct stages: first capturing the entire bonded wafer structure (wafer, support plate, and adhesive member) to locate the outer peripheral edge, then capturing the inner peripheral edge after removing the adhesive member. This segmentation allows accurate detection of the outer edge position even when the adhesive member is present and sticking out, by treating the detection of different edges as separate tasks performed at different times.
Solution Approach 2:
The patent performs the imaging of the outer peripheral edge before removing the adhesive member, capturing this information in advance. This preliminary action ensures that the outer edge position is recorded while the adhesive member is still in place, eliminating the need to wait for adhesive removal before determining the outer edge location, thus improving overall process efficiency.
2Ease of operation
If the adhesive member sticks out on the outer peripheral edges, then the wafer can be handled more easily, but it is difficult to determine which edge represents the outer peripheral edge of the bonded wafer
Solution Approach 1:
The patent segments the edge detection task into two parts: detecting the outer peripheral edge when the adhesive member is present, and detecting the inner peripheral edge after adhesive removal. By capturing images at these two distinct stages, the system can clearly identify which edge corresponds to the outer peripheral edge of the bonded wafer, eliminating confusion caused by the adhesive member sticking out.
Solution Approach 2:
The patent uses feedback from the imaging process to identify edges. By capturing images at different stages (with and without adhesive member) and comparing the detected edge positions, the system can determine which edge represents the outer peripheral edge of the bonded wafer, providing a feedback mechanism that resolves the identification difficulty.
3Ease of manufacture
If imaging is performed from above to capture the bonded wafer, then the process is simple, but accurate detection of the outer peripheral edge position cannot be ensured
Solution Approach 1:
The patent performs preliminary imaging of the outer peripheral edge from above before removing the adhesive member. This preliminary action captures the outer edge position information in advance when the adhesive member is still providing structural context, ensuring accurate detection without requiring complex imaging procedures.
Solution Approach 2:
The patent segments the imaging process into two simple steps: first imaging from above to capture the outer peripheral edge position, then imaging after adhesive removal to capture the inner peripheral edge. This segmentation maintains the simplicity of top-down imaging while improving accuracy by performing detections at appropriate stages.
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
Enables accurate detection of the wafer's edge position, reducing errors and ensuring precise cutting, even with complex bonded wafer structures, by differentiating the edge from the support plate and adhesive member in the captured image.
Implementation Method 1
irradiating means for irradiating an outer peripheral edge of the bonded wafer with light through a through hole defined in the chuck table and extending vertically therethrough
Implementation Method 2
imaging the outer peripheral edge of the bonded wafer with imaging means disposed in facing relation to the irradiating means with the bonded wafer interposed therebetween, thereby to capture an image
Data Source
AI summary
A wafer is bonded to a support plate by cutting off, with a cutting blade, an annular portion of the bonded wafer which extends from the outer peripheral edge of the bonded wafer to a position that is spaced radially inwardly toward the center of the bonded wafer by a predetermined distance. Bonding is done by a method that includes a captured image forming step of irradiating the outer peripheral edge of the bonded wafer with light emitted from an irradiating unit and passing through a through hole, and imaging the outer peripheral edge of the bonded wafer with an imaging camera disposed in facing relation to the irradiating unit with the bonded wafer interposed therebetween, thereby to capture an image, and an outer peripheral edge position detecting step of detecting an outer peripheral edge position of the bonded wafer on the basis of the captured image.