Substrate Alignment Using Dual Sensors for Warped Wafer Positioning
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Solution Overview
Problem
Existing substrate processing methods face challenges in accurately positioning and aligning substrates, especially when they are warped or have translucent materials, leading to misalignment and potential damage during processing.
Innovation Solution
A substrate processing apparatus equipped with a first sensor to detect the outer shape and a second sensor to detect pre-formed characteristic points on the substrate, along with an adjusting system and controller to ensure accurate alignment, allowing for precise adjustment and attachment to a substrate holder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sensor detects corner positions to determine substrate position, then the positioning process is simple, but positioning accuracy is insufficient when substrate is significantly warped or translucent
Solution Approach 1:
The positioning system is segmented into two independent detection stages: first detecting outer shape characteristics (corners, edges) to establish preliminary position, then detecting internal characteristic points (patterns, markers) to refine positioning accuracy. This segmentation allows each sensor to focus on specific features, achieving high accuracy even with warped or translucent substrates.
Solution Approach 2:
The outer shape detection is performed as a preliminary action before final positioning. By first establishing the substrate's basic position and orientation through corner detection, the system creates a preliminary alignment that guides subsequent high-precision characteristic point detection, ensuring accurate positioning even when the substrate has complex warping or transparency issues.
2Measurement precision
If light is used to illuminate the substrate for corner detection, then corner positions can be detected with high accuracy, but light may penetrate through translucent substrates causing detection failure
Solution Approach 1:
The system uses the substrate's outer shape characteristics (corners, edges) as an intermediary to establish preliminary positioning. These geometric features serve as reliable intermediate markers that can be detected regardless of material transparency, providing a foundation for subsequent high-precision characteristic point detection.
Solution Approach 2:
The detection system changes detection parameters by switching from detecting material-dependent optical properties to detecting geometry-based physical boundaries. By focusing on corner positions and edge shapes rather than relying solely on light absorption or reflection from the substrate material, the system achieves reliable detection across different material types including translucent ones.
3Ease of operation
If the substrate is transferred by a transporter, then the substrate can be moved to the processing position, but the substrate cannot be held at a constant position and angle leading to misalignment
Solution Approach 1:
The system implements feedback control by detecting the substrate's actual position and orientation after transfer using both outer shape and internal characteristic points. The detected positional deviations are fed back to the adjusting system, which automatically corrects misalignment by adjusting the substrate holder's position and angle, ensuring precise alignment despite variations in transfer accuracy.
Solution Approach 2:
The system replaces reliance on purely mechanical transfer precision with an optical-detection-based correction system. Instead of depending on the transporter's mechanical accuracy to maintain constant position and angle, the system uses sensor detection and automated adjustment to achieve precise alignment, substituting mechanical precision requirements with detection and correction capabilities.
Data Source
AI summary
An adjusting system is controlled such that an arrangement of the substrate is adjusted based on detection by a first sensor, and a second sensor is controlled to detect a characteristic point formed in advance on a plate surface of the substrate, wherein the arrangement of the substrate has been adjusted based on the detection by the first sensor. Moreover, it is checked whether a position of the characteristic point detected by the second sensor is within an allowable range, and the adjusting system is controlled to adjust the arrangement of the substrate based on the detection by the second sensor when the position of the characteristic point detected by the second sensor is within the allowable range, and the attaching/detaching system is controlled to attach the substrate to the substrate holder after the arrangement of the substrate is adjusted based on the detection by the second sensor.