Wafer Centering Robot Compensation for Thermal Position Drift
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Solution Overview
Problem
Existing substrate processing systems face challenges in achieving precise substrate positioning due to thermal effects such as expansion and contraction of robot components, leading to inaccurate placement, which can be exacerbated by the reliance on encoder data for position correction, thereby slowing down processing time.
Innovation Solution
An imaging system is employed to capture images of robot arms at a predetermined position and compare them to calibration images to determine positional variances, allowing for independent position compensation without relying on encoder data, thereby enhancing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If encoder data is used for position correction, then substrate placement accuracy can be improved, but processing time increases due to the cumbersome correction process
Solution Approach 1:
The patent replaces the mechanical encoder-based position measurement system with an optical imaging system. The imaging system captures images of the substrate and robot arm, using optical fields instead of mechanical encoders to determine position. This substitution eliminates the cumbersome encoder data processing while maintaining measurement precision, thereby reducing processing time without sacrificing substrate placement accuracy.
2Productivity
If thermal effects are not compensated, then processing speed is maintained, but substrate placement accuracy deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the imaging system continuously monitors the actual position of the substrate and robot arm, comparing it against the commanded position. Thermal-induced deviations are detected through this feedback loop, and real-time corrections are applied to subsequent movements. This allows the system to maintain both high processing speed and accurate substrate placement by dynamically compensating for thermal effects without slowing down the overall process.
3Manufacturing precision
If encoder-based position correction is used, then manufacturing precision can be improved, but device complexity increases
Solution Approach 1:
The patent extracts the position measurement function from the mechanical encoder system and relocates it to an independent optical imaging system. This separation removes the complexity of encoder data processing, interpolation, and correction algorithms from the control system. The imaging system independently captures images and calculates position, simplifying the overall system architecture while maintaining or improving position accuracy through direct optical measurement rather than mechanical sensing.
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 handling accuracy by correcting for thermal-induced positional errors, ensuring precise substrate placement and reducing processing time by eliminating the need for cumbersome encoder-based corrections.
Implementation Method 1
thermal expansion and contraction of the substrate transport robot may shift a position of the substrate from the desired position
Implementation Method 2
thermal expansion and contraction of the substrate transport robot may shift a position of the substrate from the desired position
Data Source
Figure 1A~1F
Figure 1C~1E
Figure 2A
AI summary
A substrate transport apparatus including a transport chamber, a drive section, a robot arm having an end effector at a distal end configured to support a substrate and being connected to the drive section generating at least arm motion in a radial direction extending and retracting the arm, an imaging system with a camera mounted in a predetermined location to image at least part of the robot arm, and a controller connected to the imaging system to image the arm moving to a predetermined repeatable position, the controller effecting capture of a first image of the robot arm proximate to the repeatable position decoupled from encoder data of the drive axis, wherein the controller calculates a positional variance of the robot arm from comparison of the first image with a calibration image, and from the positional variance determines a motion compensation factor changing the extended position of the robot arm.