Workpiece Temperature Differential for Lithography Chuck Alignment
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Solution Overview
Problem
In lithography systems, particularly EUV or electron-beam systems, the workpiece can slip relative to the chuck during the transition from atmospheric pressure to vacuum, leading to alignment issues and degradation of feature quality due to differential thermal expansion between the workpiece and the chuck.
Innovation Solution
A temperature controller is used to create a predetermined temperature differential between the workpiece and the chuck by pre-heating the workpiece or pre-chilling the chuck, ensuring balanced heat flow and predictable thermal expansion during exposure, thereby maintaining alignment and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the workpiece and chuck are clamped at atmospheric pressure and then transitioned to vacuum, then the workpiece can be retained by the chuck, but the workpiece may slip relative to the chuck during pressure transition due to differential thermal expansion
Solution Approach 1:
The patent applies preliminary action by pre-heating the workpiece or pre-chilling the chuck before the pressure transition to vacuum. This advance temperature adjustment ensures that thermal expansion or contraction occurs before clamping, preventing differential expansion during the critical pressure transition phase and thereby preventing workpiece slippage while maintaining alignment precision.
2Manufacturing precision
If temperature control is applied to prevent differential thermal expansion, then alignment precision is improved, but system complexity increases due to additional temperature control mechanisms
Solution Approach 1:
The patent applies local quality by implementing temperature control specifically at the workpiece-chuck interface rather than controlling the entire system uniformly. Temperature control is localized to either the workpiece or the chuck, creating a targeted temperature differential that compensates for differential thermal expansion only where needed, thereby improving alignment precision without proportionally increasing overall system 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 prevents workpiece slippage and maintains consistent thermal conditions, enhancing the overlay performance and accuracy of the lithography system by balancing heat flow and thermal expansion between the workpiece and the chuck.
Implementation Method 1
the problem of differential thermal expansion between the workpiece and the chuck during the exposure process is solved by pre-heating the workpiece and/or pre-chilling the chuck to achieve the predetermined temperature differential prior to exposure
Implementation Method 2
a heater that is secured to one of the chuck and the chuck temperature controller... the heater can be selectively controlled to compensate for variations in the illumination beam
Data Source
AI summary
An exposure apparatus (10) for transferring one or more features to a workpiece (22) includes an illumination source (44A); (ii) a chuck (40) that retains the workpiece (22); (iii) a chamber housing (28A) that encircles the chuck and the workpiece; and (iv) a temperature controller (32) (34) that adjusts the temperature of at least one of the chuck (40) and the workpiece (22) so that a predetermined temperature differential (309) exists between the chuck (40) and the workpiece (22) before transferring the features to the workpiece (22).