Substrate Misalignment Detection via Suction-Stage Imaging
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Solution Overview
Problem
Existing substrate misalignment detection methods fail to accurately detect misalignment when the substrate is not held by suction, leading to potential misalignment during transfer, which can affect the stability and throughput of the inspection process.
Innovation Solution
A method that involves acquiring first and second image information or position information of the substrate at different height positions, comparing these to detect misalignment, and using this information to determine abnormality and correct misalignment, employing a camera to capture images and a controller to manage the suction state and pin positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If substrate misalignment detection is performed when substrate is held by suction, then misalignment can be detected during stable holding, but misalignment cannot be accurately detected when substrate is not held by suction during transfer
Solution Approach 1:
The system performs preliminary misalignment detection when the substrate is stably held by suction before transfer, capturing image information at this stable state. This preliminary detection allows the system to establish a reference state and predict potential misalignment issues before they occur during the transfer process, enabling proactive correction rather than reactive detection.
Solution Approach 2:
The system implements a feedback mechanism where misalignment detection results from the suction-held state are used to control the transfer process. The detected misalignment information is fed back to adjust transfer parameters or trigger correction actions, ensuring that misalignment issues are addressed based on prior detection data rather than attempting detection during the unstable transfer state itself.
2Productivity
If substrate is transferred from stage to holder, then substrate position changes during transfer, but this position change causes misalignment detection errors
Solution Approach 1:
The system performs misalignment detection and correction actions before the substrate transfer begins. By completing the detection cycle while the substrate is securely held on the stage, the system establishes accurate positioning data that can guide the transfer process, preventing position changes from causing detection errors.
Solution Approach 2:
The detection process is segmented into distinct phases: detection during stable suction holding, separate transfer execution, and post-transfer verification. This segmentation isolates the detection function from the transfer motion, allowing each process to optimize for its specific requirement without interference from the other.
3Loss of time
If misalignment detection is performed during substrate transfer, then real-time detection is achieved, but detection accuracy decreases due to substrate movement
Solution Approach 1:
The system performs misalignment detection as a preliminary action before substrate transfer begins. This timing strategy captures image information when the substrate is stationary and securely held, ensuring maximum measurement accuracy. The detection results are then used to guide subsequent transfer operations, achieving both accuracy and timely intervention.
Solution Approach 2:
The system cushions against potential misalignment issues by detecting and correcting them beforehand during the stable suction phase. This prior cushioning prevents misalignment from developing during transfer, eliminating the need for risky real-time detection during motion while maintaining both accuracy and process efficiency.
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 allows for accurate detection and correction of substrate misalignment, ensuring stable and high-throughput inspection processes by identifying misalignment even when the substrate is not held by suction, thereby improving the reliability of substrate transfer and inspection.
Implementation Method 1
acquiring first image information or first position information of a substrate held to a stage by suction at a first height position
Data Source
AI summary
A substrate misalignment detection method includes: acquiring first image information or first position information of a substrate held to a stage by suction at a first height position; delivering the substrate from the stage to a holder in a state in which the suction of the substrate is released and causing the holder to hold the substrate at the first height position; acquiring second image information or second position information of the substrate held at the first height position; and detecting misalignment of the substrate by comparing the first image information with the second image information or by comparing the first position information with the second position information.