Embedded Vision Feedback for Thermal Compensation of Robot Arms
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Solution Overview
Problem
Conventional substrate handling systems in semiconductor automation face challenges in maintaining accuracy due to high temperature variations and corrosive environments, which can lead to undesirable changes in cluster tool configurations and insufficient feedback for thermal growth or contraction, affecting the precision of substrate placement.
Innovation Solution
A vision-based sensor system is employed outside the vacuum environment to measure arm link positions of the substrate transport apparatus, providing high accuracy feedback and thermal compensation without modifying the substrate processing apparatus or adding electronics to the vacuum environment, allowing for precise adjustments to the robot kinematic model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vision systems are used at process module stations to provide position feedback, then substrate handling accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The vision system is extracted from the vacuum environment (process module stations) and relocated to the atmospheric environment (outside the vacuum chamber). This removes the sensing equipment from the harsh vacuum environment, simplifying the vacuum system design while maintaining substrate handling accuracy through external optical measurement of the robot arm position.
Solution Approach 2:
A transparent window is introduced as an intermediary element that allows optical signals to pass from the atmospheric environment to the vacuum environment. This enables the vision system to measure the robot arm position without requiring sensors inside the vacuum chamber, reducing system complexity while maintaining measurement capability.
2Measurement precision
If sensors are placed inside the vacuum environment to measure robot position, then measurement accuracy is improved, but reliability decreases due to harsh environmental conditions
Solution Approach 1:
The vision sensors are extracted from the vacuum environment and placed in the atmospheric environment outside the vacuum chamber. This protects the sensitive optical sensors from harsh conditions (vacuum, high temperature, corrosive gases) while maintaining measurement accuracy through optical observation through a transparent window.
Solution Approach 2:
Instead of placing physical sensors inside the vacuum chamber, the system creates an optical copy/image of the robot arm position by capturing images through a transparent window. This allows accurate position measurement without exposing sensors to the harsh vacuum environment.
3Manufacturing precision
If additional position feedback devices are added to compensate for thermal effects, then substrate placement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The external vision system serves multiple functions: it provides position feedback for substrate placement accuracy, measures thermal expansion/contraction of the robot arm, and enables compensation for environmental effects. This single external system replaces multiple specialized sensors that would otherwise be needed inside the vacuum chamber.
Solution Approach 2:
The vision system continuously captures images of the robot arm to provide real-time position feedback. This feedback is used to detect thermal expansion or contraction of the robot arm and to compensate for these changes, maintaining substrate placement accuracy without requiring additional specialized sensors.
4Measurement precision
If sensing technology is placed in proximity to aggressive environments, then position feedback is obtained, but reliability and durability decrease
Solution Approach 1:
The vision sensors are extracted from the aggressive vacuum environment and placed in the benign atmospheric environment outside the vacuum chamber. This protects the sensors from corrosive gases, extreme temperatures, and vacuum conditions while maintaining position measurement accuracy through optical observation.
Solution Approach 2:
A transparent window serves as an intermediary that transmits optical signals from the vacuum environment to the atmospheric environment. This allows the vision system to measure robot arm position accurately without exposing sensors to the aggressive vacuum environment, ensuring sensor reliability and durability.
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 solution enhances substrate transport placement accuracy by compensating for thermal changes and maintaining precision without interfering with the semiconductor manufacturing process or altering the substrate transport apparatus design, ensuring reliable operation in high-temperature and corrosive environments.
Implementation Method 1
an imaging system with an imaging sensor mounted through the mounting interface in a predetermined location with respect to the vacuum chamber and disposed so as to image at least part of the robot arm
Data Source
AI summary
A substrate transport apparatus includes a transport chamber, a drive section, a robot arm, an imaging system with a camera mounted through a mounting interface of the drive section in a predetermined location with respect to the transport chamber and disposed to image part of the arm, and a controller connected to the imaging system and configured to image, with the camera, the arm moving to or in the predetermined location, the controller effecting capture of a first image of the arm on registry of the arm proximate to or in the predetermined location, the controller is configured to calculate a positional variance of the arm from comparison of the first image with a calibration image of the arm, and determine a motion compensation factor changing an extended position of the arm. Each camera effecting capture of the first image is disposed inside the perimeter of the mounting interface.