Phase Change Heat Buffer for Lithography Vibration Control
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Solution Overview
Problem
High mass flow rates of thermal transfer fluids in lithography apparatuses generate vibrations that can lead to positioning errors and affect the accuracy of pattern projection and substrate measurement due to the need for high heat removal capacity to manage time-varying heat loads from active modules.
Innovation Solution
Incorporating a heat buffer with a phase change material in thermal contact with active modules, which absorbs heat during peak periods and releases it slowly, allowing for reduced thermal transfer fluid flow rates and minimizing vibrations by maintaining the phase change material's stationarity during critical operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the mass flow rate of thermal transfer fluid is increased to remove peak heat loads from active modules, then temperature control capability is improved, but vibrations are generated that affect positioning accuracy and pattern projection
Solution Approach 1:
The heat buffer is pre-positioned in thermal contact with active modules before they generate peak heat loads. The phase change material is prepared in advance to absorb heat when needed, allowing the system to respond to heat spikes without requiring high-velocity fluid flow that causes vibrations.
Solution Approach 2:
The phase change material acts as an intermediary between the active modules and the thermal transfer fluid system. It absorbs peak heat loads directly at the source through phase change, mediating the heat transfer process and eliminating the need for high mass flow rates that generate harmful vibrations.
2Manufacturing precision
If the mass flow rate of thermal transfer fluid is reduced to eliminate vibrations, then positioning accuracy is improved, but the ability to remove peak heat loads is compromised
Solution Approach 1:
The system changes the thermal management approach by utilizing phase change (latent heat) rather than relying solely on convective heat transfer through high-velocity fluid flow. This parameter change allows effective heat removal at low mass flow rates, maintaining positioning accuracy while managing peak heat loads.
Solution Approach 2:
The phase change material is pre-positioned and prepared to absorb heat at the moment of peak heat generation. This preliminary preparation allows the system to have high heat removal capacity available on-demand without requiring continuous high-velocity fluid flow, thus maintaining low vibrations and high positioning accuracy.
3Stability of the object's composition
If high mass flow rates are used to manage heat from multiple active modules, then temperature stability is maintained, but system complexity and vibration damping requirements increase
Solution Approach 1:
The phase change material provides self-service thermal management by automatically absorbing peak heat loads through phase change when active modules generate excess heat. This self-regulating mechanism maintains temperature stability without requiring complex vibration damping systems or high-velocity fluid flow control mechanisms.
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 reduces vibrations and maintains temperature stability within the lithography apparatus, enabling precise temperature control and improved accuracy in pattern projection and substrate measurement by moderating peak heat outputs and allowing for reduced mass flow rates of thermal transfer fluids.
Implementation Method 1
a heat buffer comprising a phase change material in thermal contact with the active module, the phase change material having a phase change temperature such that the phase change material is caused to undergo a phase change by the time-varying heat load
Implementation Method 2
the phase change material is caused to undergo a phase change by the time-varying heat load
Implementation Method 3
The temperature control system in a lithography apparatus may operate by circulating a thermal transfer fluid, e.g. water, through a conduit close to or in a component whose temperature is to be controlled
Data Source
AI summary
A lithography apparatus includes: a projection system configured to project a desired image onto a substrate; an active module that generates a time-varying heat load; a temperature conditioning system configured to maintain a component of the lithography apparatus at a predetermined target temperature; and a heat buffer including a phase change material in thermal contact with the active module, the phase change material having a phase change temperature such that the phase change material is caused to undergo a phase change by the time-varying heat load, and wherein the phase change material is stationary relative to the projection system during critical operations of the lithography apparatus.