Wafer Center Detection Using End Effector Aperture Sensing
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Solution Overview
Problem
Wafer transfer robots in semiconductor fabrication facilities face challenges in securely and efficiently transferring wafers, balancing speed and safety to prevent damage to valuable wafers.
Innovation Solution
The implementation of a wafer transfer robot system equipped with end effectors featuring vacuum ports, wafer edge detection modules, and a networked environment for precise control and communication between nodes, enabling secure and efficient wafer transfer operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wafer transfer robot operates at high speed, then productivity is improved, but the risk of wafer damage increases
Solution Approach 1:
The system performs preliminary detection of the wafer center position using optical sensors before the transfer operation begins. This advance detection allows the robot to plan and execute the transfer motion with precise positioning, enabling high-speed operation while maintaining wafer safety through pre-planned accurate placement.
Solution Approach 2:
The optical detection module provides real-time feedback on wafer position and center location. This feedback loop allows the control system to adjust transfer parameters dynamically, ensuring that even at high speeds, the wafer is transferred securely to the correct position without damage.
2Reliability
If vacuum port pressure is increased to secure wafer, then transfer reliability is improved, but wafer damage risk increases
Solution Approach 1:
Instead of applying uniform high vacuum pressure across the entire wafer surface, the system uses multiple vacuum ports that apply localized suction at specific contact points. This localized approach provides secure holding while distributing the force to prevent damage to the wafer surface.
Solution Approach 2:
The system uses just enough vacuum pressure to securely hold the wafer during transfer, avoiding excessive pressure that would cause damage. The vacuum level is optimized to provide sufficient holding force for reliable transfer while remaining below the threshold that could harm the wafer.
3Measurement precision
If detection precision is increased to locate wafer center, then transfer accuracy is improved, but device complexity increases
Solution Approach 1:
The system replaces complex mechanical measurement systems with optical detection methods. Optical sensors and image processing algorithms are used to detect the wafer center position with high precision, avoiding the need for complex mechanical probing or contact-based measurement systems.
Solution Approach 2:
The optical detection system creates an optical image or representation of the wafer position and uses image processing to determine the center location. This copying approach allows precise measurement without physical contact or complex mechanical structures.
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 ensures fast and secure wafer transfer, minimizing the risk of damage and optimizing productivity in semiconductor fabrication facilities by utilizing precise detection and control mechanisms.
Implementation Method 1
Located on each end effector 102 are one or more vacuum ports 114. The vacuum ports 114 are used to secure an item such as a wafer 116 on top of the end effector 102.
Implementation Method 2
Two up-firing sensors 506 are spaced laterally apart and fire upwardly transverse to the direction of movement of the end effector 102. A central up-firing sensor 504 fires upwardly in the direction of movement of the end effector 102.
Data Source
AI summary
A robot system includes a robot arm and an end effector coupled to the robot arm for receiving an item, the end effector having an aperture defined therein that is partially covered by an item when the item is received by the end effector. The system may include data processors in communication with the robot arm and an input to receive data from a sensor that can detect obstruction thereof as the end effector is moved past the sensor with the aperture aligned with the sensor. The robot system is able to determine a center of the item from positional information captured during sensor transitions. The robot system can then place the item such that the determined center of the item is received at an intended center location. Also disclosed is an end effector coupled to the robot arm for receiving an item, the end effector having sensor regions that are obscured when an item is received by the end effector, and a sensor module directed at the sensor regions on the end effector, the sensor module and the sensor regions in combination being operable to detect when the item obscures the sensor regions.