Substrate Inspection Stage Alignment via Quadrant Axis Deviation Correction
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Solution Overview
Problem
In substrate inspection apparatuses, inaccuracies in stage alignment occur due to deviations in the rotational direction of the camera's coordinate system axes relative to the stage's movement directions, leading to incorrect displacement calculations and misalignment.
Innovation Solution
The method involves calculating and correcting deviations of the X and Y axes in each quadrant of the camera's coordinate system, allowing for precise alignment of the stage by adjusting the position of the target mark based on calculated rotation correcting angles and conversion coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the camera is installed to photograph the stage for alignment, then the stage position can be detected, but the coordinate system axes of the camera may deviate from the stage movement directions due to installation errors or lens aberration, causing alignment inaccuracy
Solution Approach 1:
The patent applies parameter changes by calculating rotation correcting angles for each quadrant and using these parameters to transform the coordinate system. The control part computes correction values based on the photographed target position and applies rotational transformation to align the camera coordinate system with the stage movement directions, thereby resolving the axis deviation issue
Solution Approach 2:
The patent handles the asymmetric deviation of coordinate axes by calculating different rotation correcting angles for each of the four quadrants. This asymmetric approach allows precise correction of axis misalignment in each region, improving overall alignment accuracy despite installation errors or lens aberrations
2Ease of operation
If the distance from the target position to the origin is calculated and converted to displacement amount for alignment, then the stage can be positioned, but the displacement amount becomes inaccurate due to rotational deviation of the coordinate system axes
Solution Approach 1:
The patent transforms the simple distance calculation approach into a more complex but accurate method by calculating rotation correcting angles and applying coordinate transformation. The control part uses these angular parameters to compute corrected displacement amounts that account for axis deviation, maintaining ease of operation while improving precision
Solution Approach 2:
The patent introduces rotation correcting angles as an intermediary parameter between the camera coordinate system and the stage movement directions. This intermediary allows accurate translation of target position to stage displacement by compensating for coordinate system misalignment, ensuring both ease of operation and measurement precision
Data Source
AI summary
A method of controlling a substrate inspection apparatus, which includes a stage configured to mount a substrate thereon and move in first and second moving directions and a camera configured to photograph the stage. The method includes: calculating in each quadrant divided by X and Y axis defining a coordinate system of an image photographed by the camera, a deviation of the X axis in a rotational direction with respect to the first moving direction or a deviation of the Y axis in the rotational direction with respect to the second moving direction; correcting a position of a photographed target in the coordinate system of the image photographed by the camera based on the calculated deviation in the rotational direction; and performing an alignment of the stage based on the corrected position of the target.