Lithography Apparatus ZX Bar Mirror Height Error Correction
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Solution Overview
Problem
In lithography apparatuses, relative errors between ZX bar mirrors on different stations cause focusing and leveling errors, leading to reduced positioning precision and image blur, especially due to shape changes over time that cannot be corrected by existing zero-point matching methods.
Innovation Solution
A lithography apparatus with a substrate holder and multiple measuring devices that measure and correct for height and shape errors between ZX bar mirrors, using a controller to obtain correction values and adjust for high-order errors, ensuring precise positioning and focusing by averaging measurements from multiple interferometers and adjusting for high-order shape deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple ZX bar mirrors are used on different stations to enable parallel measurement and exposure operations, then productivity is improved, but measurement precision deteriorates due to relative errors between mirror shapes
Solution Approach 1:
The system continuously measures the relative error between ZX bar mirrors using laser interferometers and automatically generates correction values that are applied to the measurement data. This feedback mechanism compensates for shape deviations in real-time, maintaining measurement precision while enabling parallel operations on multiple stations
Solution Approach 2:
The system changes the measurement parameters by introducing correction values that adjust the raw measurement data from multiple ZX bar mirrors. By applying these parameter corrections based on measured relative errors, the system eliminates the deteriorating effect of mirror shape variations while preserving the productivity benefits of multiple stations
2Measurement precision
If zero-point matching is used to correct low-order errors between ZX bar mirrors, then measurement precision is improved for low-order components, but high-order shape errors remain uncorrected causing positioning errors
Solution Approach 1:
The correction process is segmented into different error components: zero-point matching handles low-order errors (zeroth and first order), while a separate correction mechanism using measured relative errors addresses high-order shape errors (second order and above). This segmentation allows each correction method to target its specific error range effectively
Solution Approach 2:
The system performs preliminary zero-point matching to correct low-order errors before applying the additional correction values for high-order errors. This preliminary action ensures that both low-order and high-order errors are systematically addressed in sequence, achieving comprehensive precision correction
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 enhances positioning precision by correcting for high-order shape errors in ZX bar mirrors, reducing defocus and blur, and enabling self-correction during operation without reducing throughput, thus improving the accuracy of pattern projection on substrates.
Implementation Method 1
a measuring device that is capable of measuring the distance between the top surface (top plate surface) of a stage and a surface plate on which a projection optical system is secured and includes a laser interferometer exhibiting excellent linearity and high resolution
Data Source
AI summary
A lithography apparatus includes a measuring station that includes a first measuring device configured to measure a height of a substrate holder, and a second measuring device configured to measure a height of a surface of a substrate held by the holder, and a patterning station that includes a third measuring device configured to measure a height of the holder, and patterns the substrate held by the holder based on an output of the second measuring device. The patterning station includes a fourth measuring device configured to measure a height of a surface of a substrate held by the holder. The lithography apparatus includes a controller configured to obtain a correction value for an output obtained from at least one of the first and third measuring devices based on outputs of the second and fourth measuring devices with respect to a substrate held by the holder.