Wafer Groove Alignment Using Dual-Side Imaging Correction
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Solution Overview
Problem
Existing methods for cutting silicon wafers to create device chips face challenges with misalignment of center lines on both sides of the workpiece, leading to issues like oblique cutting and failure to meet specification requirements for chip shape.
Innovation Solution
A processing method that involves forming processing grooves on both sides of the workpiece, using imaging units to detect and correct the alignment of center lines, and then connecting these grooves to ensure precise cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If alignment marks are imaged through transparent holding table windows, then alignment can be performed, but distortion in the shape of alignment marks causes misalignment of center lines
Solution Approach 1:
The patent creates a virtual copy of the alignment mark by projecting light through the transparent holding table to form an image of the mark on the workpiece. This optical copying method allows alignment without direct contact with the physical alignment mark, eliminating distortion issues while maintaining alignment accuracy.
Solution Approach 2:
The patent introduces light as an intermediary medium between the alignment mark and the workpiece. By projecting light through the transparent holding table, the system creates an optical pathway that transfers the alignment mark information without the physical distortion that would occur with direct imaging through the table material.
2Manufacturing precision
If V-shaped grooves are formed on both sides of the workpiece, then cutting accuracy can be improved, but misalignment of center lines causes oblique cutting
Solution Approach 1:
The patent implements a feedback mechanism where the positions of V-shaped grooves on both sides of the workpiece are measured and compared. When misalignment is detected, the system adjusts the cutting parameters to correct the center line alignment, ensuring that subsequent cuts are properly aligned and oblique cutting is prevented.
Solution Approach 2:
The patent performs preliminary alignment of the center lines by forming V-shaped grooves and measuring their positions before completing the final cutting operation. This preliminary action allows the system to detect and correct misalignment issues before they affect the final cut quality, preventing oblique cutting.
3Productivity
If the cutting blade cuts into the workpiece obliquely, then cutting can proceed, but center line misalignment occurs between face side and reverse side
Solution Approach 1:
The patent introduces dynamic adjustment capability to the cutting system, allowing the cutting blade position and angle to be adjusted in real-time based on detected misalignment. This dynamic adjustment enables the system to maintain high cutting speed while correcting center line alignment issues that would otherwise cause oblique cutting.
Solution Approach 2:
The patent changes cutting parameters such as blade position, angle, and depth based on detected misalignment conditions. By dynamically adjusting these parameters, the system can compensate for center line misalignment and prevent oblique cutting while maintaining efficient cutting speeds.
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 improves processing accuracy by directly observing and correcting misalignments between center lines on the face and reverse sides of the workpiece, allowing for accurate alignment and reducing the occurrence of oblique cutting.
Implementation Method 1
imaging the first processing groove by a first imaging unit, in a state in which the workpiece is held by a holding table having an area formed with a transparent material
Data Source
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AI summary
A processing method for a workpiece includes forming a first processing groove by a first processing unit, imaging the first processing groove by a first imaging unit and imaging, by a second imaging unit provided on an opposite side of the first imaging unit with respect to the holding table, a predetermined line that is formed in a position corresponding to that of the first processing groove in a thickness direction of the workpiece, detecting whether or not a position of a first center line of the first processing groove and a position of a second center line of the predetermined line are aligned in a predetermined plane, and correcting the processing position in such a manner as to make the positions of the two center lines aligned when the detected positions of the first center line and the second center line are not being aligned.