ALBEMET and INVAR Mirror Support Structure for Resonance Control
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Solution Overview
Problem
At the nanometer and picometer levels, equipment vibrations and irregularities pose significant challenges for precise operations due to resonance issues, which are difficult to mitigate with existing technologies that rely on increasing size or reducing energy input, as these approaches often result in reduced natural frequency and increased sensitivity to thermal vibrations.
Innovation Solution
A high stiffness, low mass supporting structure with ALBEMET fingers and an INVAR annulus is employed, along with sensors to detect input energy and monitor natural frequency, triggering an alarm to prevent resonance by adjusting the structure's configuration or halting operations when resonance is imminent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the size of mechanical elements is increased to achieve higher stiffness, then the natural frequency of the structure increases, but the mass of the structure increases
Solution Approach 1:
The patent employs ALBEMET (a beryllium-copper alloy) and INVAR (a nickel-iron alloy) to construct the supporting structure. ALBEMET provides high stiffness-to-weight ratio for the arms and fingers, while INVAR offers low thermal expansion and high stiffness for the annular ring and chuck. This composite material approach achieves high stiffness without proportionally increasing mass, thereby increasing natural frequency while minimizing weight penalties.
2Weight of moving object
If the size of mechanical elements is decreased to reduce mass, then the natural frequency of the structure decreases, but the stiffness is reduced
Solution Approach 1:
By using ALBEMET and INVAR, the patent achieves high stiffness in compact components. These materials have inherently high elastic moduli, allowing small-diameter arms, thin fingers, and compact annular rings to maintain high stiffness. This enables the structure to be miniaturized while preserving natural frequency characteristics.
3Reliability
If sensors and monitoring systems are added to detect resonance, then the ability to prevent damage improves, but the device complexity increases
Solution Approach 1:
The patent incorporates sensors that continuously monitor the supporting structure for vibrations and resonance conditions. When resonance is detected, the system provides feedback through an alarm or to a control system that can adjust operating parameters or halt operations. This feedback mechanism prevents catastrophic failure while maintaining operational efficiency, and the automated nature of the monitoring minimizes the operational burden despite the added complexity.
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 effectively increases the natural frequency of the supporting structure, reducing resonance-induced disruptions and maintaining operational accuracy at extremely small dimensions by using advanced materials and real-time feedback mechanisms.
Implementation Method 1
The fingers can be made of ALBEMET to achieve high stiffness at a low mass, to increase the overall natural frequency of the structure
Implementation Method 2
The annulus can be constructed of INVAR
Implementation Method 3
sensors can be employed to detect input energy sources and the frequency of such input
Implementation Method 4
If input energy approaches the natural frequency of the system such that resonance is likely
Data Source
AI summary
Systems and methods of providing support to a mirror assembly including a high-stiffness, low mass structure. An L-shaped support, in conjunction with a shelf member and a plurality of fingers, provides support to a chuck upon which an operation (such as a wafer inspection) can be carried out. Materials such as ALBEMET and INVAR can be used to reduce mass and increase stiffness to avoid resonance in the system. Sensors and actuators can be employed to sense input energy and adjust the structure, respectively, if resonance is deemed likely.