Adaptive Substrate Placement via Fiducial Tracking
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Solution Overview
Problem
Substrate processing systems face challenges in achieving precise and repeatable substrate placement due to factors like vibration, thermal effects, and sensor variability, leading to inaccuracies in substrate transfer and placement.
Innovation Solution
A substrate transport robot equipped with a system that determines the location of a fiducial on a substrate using image sensors or cameras, compares it to a reference location, and adjusts the end effectors' movement to ensure precise placement, utilizing a controller with processors and memory to execute algorithms for adaptive placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sensors and algorithms are added to detect and correct placement variables, then placement precision is improved, but device complexity increases
Solution Approach 1:
The system performs preliminary measurement of the substrate's actual position and orientation using image sensors before the placement operation. This advance detection allows the control algorithm to calculate and apply correction values to the robot's movement commands, ensuring precise placement despite initial positioning errors or environmental disturbances.
Solution Approach 2:
The system implements a feedback mechanism where image sensors continuously monitor the substrate's position and orientation during transport. The measured deviations from the reference fiducial location are fed back to the controller, which adjusts the robot's placement commands in real-time to compensate for errors and achieve accurate substrate placement.
2Measurement precision
If calibration accuracy is increased to reduce placement error, then measurement precision is improved, but the system becomes more sensitive to calibration errors
Solution Approach 1:
The system performs self-calibration by using the substrate's own fiducial markers as reference points. The image sensors capture images of these fiducials, and the control algorithm automatically calculates the substrate's position and orientation relative to the reference frame without requiring external calibration equipment or manual intervention, thereby reducing sensitivity to external calibration errors.
Solution Approach 2:
The system dynamically adjusts measurement and placement parameters based on real-time feedback from image sensors. By continuously monitoring fiducial locations and recalculating placement parameters during operation, the system adapts to calibration variations and maintains accurate placement without being constrained by fixed calibration settings.
3Manufacturing precision
If substrate transport is performed with high precision requirements, then placement accuracy is improved, but productivity decreases
Solution Approach 1:
The system captures images of the substrate's fiducial markers during transport at predetermined positions, allowing measurement and correction calculations to be performed in advance or during movement. This eliminates the need for slow, step-by-step positioning adjustments and enables high-speed transport while maintaining placement precision through pre-calculated correction values.
Solution Approach 2:
The image sensors and control algorithms operate continuously during substrate transport, performing real-time measurement and correction without interrupting the robot's movement. This continuous operation allows high-speed substrate handling to proceed uninterrupted while maintaining accurate placement through ongoing feedback and adjustment.
Data Source
AI summary
A method including moving a substrate, located on a first end effector of a robot, from a first location towards a second location by the robot; determining location of a fiducial on the substrate while the substrate is being moved from the first location towards the second location; comparing the determined location of the fiducial with a reference fiducial location while the robot is moving the substrate from the first location towards the second location.