Linear Induction Wafer Transport Without Vacuum Bearings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional wafer handlers operating in vacuum environments face challenges such as lubricant outgassing, particle generation, and friction variability due to the use of bearings, and are not suitable for 'long' vacuum cluster tools like linear tool configurations, which require mechanical designs with low natural frequencies and increased sensitivity to thermal expansion.
Innovation Solution
The development of a magnetic levitated substrate transport apparatus based on linear induction technology, which uses a paramagnetic base and an array of electromagnets to provide lift, lateral stabilization, and propulsion, eliminating the need for bearings and allowing for scalable substrate handling without mechanical stroke limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bearings are used in vacuum environment, then mechanical support and motion control are achieved, but lubricant outgassing, particle generation, and friction variability occur
Solution Approach 1:
The patent replaces conventional mechanical bearings with a magnetic bearing system that uses magnetic fields to support and control the motion of the wafer handler. This substitution eliminates the need for lubricants in vacuum environment, thereby preventing lubricant outgassing and particle generation while maintaining reliable mechanical support and motion control.
Solution Approach 2:
The patent changes the operating parameters of the bearing system by transitioning from mechanical contact with lubricants to magnetic field-based support. This parameter change enables operation in vacuum environment without the harmful effects associated with conventional bearings, achieving both reliability and vacuum compatibility.
2Length of moving object
If long arm link lengths are used in linear tool configurations, then reach distance is increased, but mechanical positioning hysteresis and arm link deflection increase
Solution Approach 1:
The patent replaces the mechanical arm link structure with a magnetic field-based positioning system. This substitution eliminates mechanical positioning hysteresis and reduces arm link deflection by using magnetic forces for precise position control, thereby maintaining positioning accuracy even with increased reach distance in linear tool configurations.
3Productivity
If magnetic levitation is used for substrate transport, then mechanical deflection is reduced and throughput is increased, but system complexity increases
Solution Approach 1:
The patent implements a magnetic levitation system that performs multiple functions: substrate transport, positioning, and stabilization. By integrating these functions into a single magnetic field-based system, the patent achieves high substrate throughput while managing system complexity through multi-functionality rather than separate mechanical components.
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 enables high-speed substrate processing with reduced mechanical deflection and increased throughput, while maintaining contact between the wafer and the end effector without slippage, and allows for coordinated operation of multiple substrate handlers to avoid collisions and reduce the footprint of the substrate processing apparatus.
Implementation Method 1
magnetic levitated substrate transport apparatus based on linear induction technology, which uses a paramagnetic base and an array of electromagnets to provide lift
Implementation Method 2
magnetic levitated substrate transport apparatus based on linear induction technology
Implementation Method 3
array of electromagnets to provide lift, lateral stabilization, and propulsion
Implementation Method 4
array of electromagnets to provide lift, lateral stabilization, and propulsion
Data Source
AI summary
A linear electrical machine comprising a frame with a level reference plane and an array of electromagnets, connected to the frame to form a drive plane at a predetermined height relative to the reference plane. The array of electromagnets being arranged so that a series of electromagnets of the array of electromagnets define at least one drive line within the drive plane, and each of the electromagnets being coupled to an alternating current power source energizing each electromagnet. At least one reaction platen of paramagnetic, diamagnetic, or non-magnetic conductive material disposed to cooperate with the electromagnets of the array of electromagnets so that excitation of the electromagnets with alternating current generates levitation and propulsion forces against the reaction platen that controllably levitate and propel the reaction platen along at least one drive line, in a controlled attitude relative to the drive plane.