Transparent Chuck Table Kerf Detection for Semiconductor Wafers
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Solution Overview
Problem
Existing dividing apparatuses face challenges in confirming whether dividing grooves, or kerfs, extend completely through semiconductor wafers between upper and lower surfaces, making it difficult to reattempt the dividing process if the grooves are incomplete.
Innovation Solution
A dividing apparatus with a chuck table featuring a transparent plate and suction ports, equipped with illumination units and an image capturing system to detect and measure the presence and width of kerfs, allowing for real-time assessment of kerf formation and adjustment to ensure complete separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light is applied to the wafer from one surface side after the wafer is separated from the chuck table, then the dividing grooves can be confirmed, but it becomes difficult to perform the dividing process again if the grooves are incomplete
Solution Approach 1:
The patent applies preliminary action by performing the image capture and groove verification process while the wafer is still held on the chuck table, before the wafer is separated. This allows the dividing process to be confirmed or corrected while the workpiece remains in position, enabling easy rework if grooves are incomplete without requiring repositioning or re-clamping operations
2Ease of operation
If the wafer is separated from the chuck table before inspection, then the wafer can be handled independently, but the dividing process cannot be reattempted if grooves are defective
Solution Approach 1:
The inspection is performed as a preliminary action before wafer separation, ensuring that groove completeness is verified while the wafer remains secured on the chuck table. This sequence allows defective grooves to be detected and corrected while the wafer is still in position, maintaining both independent handling capability and dividing groove reliability
3Device complexity
If traditional illumination methods are used, then the setup is simple, but accurate confirmation of kerf formation and width is difficult
Solution Approach 1:
The patent applies local quality by positioning the illumination unit specifically between the chuck table and base to provide targeted illumination from below, while the image capturing unit captures images from above. This localized illumination arrangement optimizes light transmission through the transparent chuck table and workpiece, enabling accurate kerf detection and width measurement without requiring complex overall system redesign
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 confirmation of kerf formation and width, allowing for appropriate processing of semiconductor wafers into device chips, preventing defective divisions and ensuring proper kerf alignment within the wafer's streets.
Implementation Method 1
a lower illumination unit disposed between the transparent plate and the base for illuminating the holding surface
Implementation Method 2
suction ports providing fluid communication between the upper surface and a suction source to cause the upper surface to function as a holding surface
Data Source
AI summary
A dividing apparatus includes a table having a transparent plate having a holding surface for holding a workpiece thereon and a lower illumination unit for illuminating the holding surface from below, a first storage section for storing a first image including a white portion where illumination light from the lower illumination unit is transmitted through the workpiece and displayed as white and a black portion where the illumination light is blocked by the workpiece and displayed as black when an image of a kerf defined by a dividing unit in the workpiece held on the holding surface is captured by an image capturing unit with the lower illumination unit being energized, and a white pixel detecting section for detecting whether or not there are pixels in the white portion of the first image in directions perpendicular to directions along which a street extends.