Magnetically Levitated Linear Stage for EUV Lithography
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Solution Overview
Problem
The challenge in extreme ultraviolet (EUV) lithography machines is to transport photomasks or reticles within a vacuum environment without causing vibrations or contamination, while also fitting within the constrained spaces of complex lithography machines, as traditional robotic manipulator systems are too large and generate particles and friction.
Innovation Solution
A magnetically levitated linear stage (MLLS) using hysteresis motors for vibration-free movement, eliminating the need for mechanical bearings and allowing for precise positioning within the EUV lithography tools, which includes a stage driven by hysteresis motors and equipped with shock absorption systems and magnetic encoders for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional robotic manipulator systems are used to transport reticles, then the transport function is achieved, but the system size becomes too large to fit within constrained lithography machine spaces and mechanical bearings generate particles and friction causing contamination and vibrations
Solution Approach 1:
The patent replaces traditional mechanical robotic manipulator systems with a magnetically levitated linear stage system. The reticle carrier is suspended by magnetic fields from permanent magnets in the stator assembly, eliminating mechanical bearings and contacts. This substitution removes the sources of particle generation and friction, thereby reducing contamination and vibrations while enabling a more compact system design without large mechanical components
Solution Approach 2:
The patent introduces magnetic fields as an intermediary between the stator assembly and the reticle carrier. Instead of direct mechanical contact, the magnetic field acts as a mediator to suspend and transport the carrier. This intermediary approach allows for contactless operation, eliminating mechanical wear and particle generation while maintaining precise control over the reticle transport
2Reliability
If mechanical bearing systems are used in reticle transport mechanisms, then mechanical support is provided, but friction and particle generation cause contamination within the vacuum environment
Solution Approach 1:
The patent replaces mechanical bearing systems with a magnetic levitation system. The reticle carrier is suspended by magnetic fields rather than mechanical bearings, eliminating friction and the generation of contaminating particles. The magnetic suspension provides stable support through electromagnetic forces while maintaining a clean vacuum environment free from mechanical contamination
Solution Approach 2:
The patent operates the reticle transport system within a vacuum environment and uses magnetic fields that do not interact with or contaminate this inert atmosphere. The magnetic levitation system maintains the purity of the vacuum environment by eliminating mechanical components that would otherwise introduce contaminants, thereby preserving the inert environment required for EUV lithography operations
3Power
If large motors and gears are used in robotic manipulator systems, then sufficient power is provided for reticle transport, but the system becomes too large to fit within constrained areas of lithography machines
Solution Approach 1:
The patent replaces large motors and gears with a magnetic levitation system using permanent magnets and electromagnetic coils. This substitution eliminates the need for bulky mechanical transmission components while providing sufficient power for reticle transport through direct electromagnetic forces. The system achieves high power density in a compact form factor, fitting within the constrained volumes of EUV lithography machines
Solution Approach 2:
The patent transitions from mechanical power transmission through gears and motors to electromagnetic field-based power transmission. By utilizing the electromagnetic dimension rather than mechanical dimensions, the system achieves the required transport power without the volumetric constraints of traditional mechanical components, enabling compact integration into lithography machine spaces
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
The MLLS effectively transports reticles within EUV lithography machines without generating significant vibrations or contaminants, maintaining ultra-tight contamination requirements and fitting within the constrained spaces, thereby improving the accuracy and quality of IC feature creation.
Implementation Method 1
A magnetically levitated linear stage (MLLS) using hysteresis motors for vibration-free movement, eliminating the need for mechanical bearings
Implementation Method 2
hysteresis motors for vibration-free movement
Implementation Method 3
equipped with shock absorption systems and magnetic encoders for precise control
Data Source
AI summary
Described herein is a magnetically levitated linear transportation stage which utilizes a permanent magnet bias flux to generate a passive magnetic/suspension force/torque in a first set of directions orthogonal to a direction of transportation stage travel, a motor flux which forms a traveling wave along a direction of transportation stage travel and a suspension control force orthogonal to the direction of transportation stage travel. Such a magnetically levitated linear transportation stage is suitable for use in in-vacuum transportation tasks such as in conjunction with photo lithography systems (e.g. extreme ultra violet (EUV) machines).