Interferometer Thermal Control via Periodic Fan Cycling
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Solution Overview
Problem
Interferometric measurement systems face challenges in achieving stable temperature control and minimizing acoustic noise and vibration, which are essential for precise measurements but often result in measurement errors due to the need for fast air circulation that generates noise and vibration.
Innovation Solution
A thermally stable mini-environment with controlled air circulation is created, where the fan speed is set to a low speed during data acquisition to minimize noise and vibration, and increased during other times, using multiple temperature sensors and heating/cooling elements to maintain a desired temperature range, synchronized with air circulation control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fast air circulation is used to maintain temperature stability, then temperature control is improved, but acoustic noise and vibration increase
Solution Approach 1:
The system implements periodic action by cycling the air circulation fan between active and inactive states. During measurement phases, the fan is turned off to eliminate noise and vibration. Between measurements, the fan activates to restore thermal equilibrium. This periodic operation resolves the contradiction by providing temperature stability only when necessary, while eliminating harmful noise during sensitive measurement periods.
Solution Approach 2:
The system dynamically adjusts fan operation based on real-time thermal conditions and measurement requirements. Temperature sensors continuously monitor the environment, and the control system adjusts fan speed or operation timing accordingly. This dynamic approach allows the system to maintain temperature stability during non-measurement periods while completely shutting down air circulation during measurement to eliminate acoustic noise and vibration.
2Object-affected harmful factors
If air circulation is turned off during measurement, then acoustic noise and vibration are minimized, but temperature stability may be compromised
Solution Approach 1:
The system performs preliminary temperature stabilization before measurement begins. The air circulation fan operates in advance to establish thermal equilibrium and stabilize the temperature environment. Once stability is achieved, the fan is turned off before measurement starts, ensuring both temperature stability has been established and acoustic noise will be minimized during the actual measurement process.
Solution Approach 2:
The system uses thermal mass and heat capacity of the enclosure and its components to maintain temperature stability passively during measurement periods. The enclosure is designed to retain heat and maintain stable temperatures without active cooling or heating during measurement, allowing the fan to remain off while preserving temperature stability through the system's inherent thermal properties.
3Measurement precision
If multiple temperature sensors and heating/cooling elements are added to maintain temperature range, then temperature control precision is improved, but device complexity increases
Solution Approach 1:
The system applies local quality by placing temperature sensors at specific critical locations within the enclosure where temperature variations most affect measurement accuracy. Rather than uniformly distributing sensors throughout the entire volume, the invention positions them strategically near the measurement zone and thermal sources. This selective approach provides sufficient temperature control precision with fewer sensors and control elements, reducing overall system complexity while maintaining measurement accuracy.
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 approach enhances measurement repeatability and precision by maintaining temperature stability and reducing acoustic noise and vibration, improving the system's ability to meet stringent requirements in microlithography at the 11 nm node and beyond.
Implementation Method 1
using multiple temperature sensors and heating/cooling elements to maintain a desired temperature range
Implementation Method 2
using multiple temperature sensors and heating/cooling elements to maintain a desired temperature range
Implementation Method 3
using multiple temperature sensors and heating/cooling elements to maintain a desired temperature range
Implementation Method 4
A thermally stable mini-environment with controlled air circulation is created
Data Source
AI summary
Disclosed herein is a method and system for providing environmental control for a vibration sensitive system such as an interferometric measurement system, while minimizing acoustic noise during data acquisition.