Projection Lens Pressure Compensation for Lithography Exposure
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Solution Overview
Problem
Lithographic apparatuses are affected by environmental pressure changes, which lead to inaccuracies in pattern projection onto substrates.
Innovation Solution
A method and apparatus that measure differential pressures across lenses, calculate imaging errors due to lens movement, and apply compensatory adjustments to lens elements, storing information on affected exposure areas to correct for these errors in subsequent exposures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If environmental pressure changes are monitored and lens adjustments are applied to compensate for imaging errors, then manufacturing precision is improved, but device complexity increases due to additional sensors and control mechanisms
Solution Approach 1:
The system performs preliminary identification and storage of exposure areas affected by pressure changes before subsequent exposures. By pre-calculating and storing imaging errors for specific exposure areas, the system enables faster compensation during production without requiring complex real-time calculations for every exposure, thus improving precision while managing complexity.
Solution Approach 2:
The system creates a copy or fingerprint of the imaging error pattern for each affected exposure area and stores it for later use. During subsequent exposures, this stored error pattern is applied to compensate for similar pressure-induced deviations, eliminating the need for repeated complex measurements and calculations, thereby maintaining high precision with reduced operational complexity.
2Manufacturing precision
If lens element adjustments are calculated and applied in real-time during exposure, then manufacturing precision is improved, but productivity decreases due to exposure delays
Solution Approach 1:
The system identifies and stores information about affected exposure areas during the delay period before lens adjustments are applied. This preliminary identification allows the system to prepare compensation strategies in advance, reducing the computational burden during actual exposure and minimizing delays, thus maintaining precision while improving throughput.
Solution Approach 2:
The system uses the stored exposure area information to automatically apply appropriate compensation for subsequent exposures without requiring complex real-time analysis. By serving itself with pre-stored error patterns, the system reduces processing time for each exposure while maintaining high precision compensation.
3Manufacturing precision
If differential pressure measurements are taken across multiple lenses, then manufacturing precision is improved through better error detection, but device complexity increases due to additional measurement points
Solution Approach 1:
The system divides the pressure measurement task into segments by measuring differential pressure across specific critical lenses rather than all lenses. By identifying key measurement points where pressure changes have the most significant impact on imaging, the system achieves high detection accuracy with a reduced number of sensors, balancing precision with manageable 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
Subsequent exposures account for imaging errors caused by pressure changes, improving pattern projection accuracy by compensating for lens element movements.
Implementation Method 1
obtaining a measurement signal of a change of a differential pressure across one or more lenses of a projection system
Data Source
AI summary
A method of controlling a projection system during exposure of a substrate by a lithographic apparatus, the method comprising obtaining a measurement signal of a change of a differential pressure across one or more lenses of a projection system of the lithographic apparatus, calculating an imaging error caused by movement of one or more lens elements of the projection system due to the change of measured differential pressure during the exposure, calculating lens element adjustments which compensate for the calculated imaging error, applying the lens element adjustments, identifying which exposure areas of the substrate were exposed during a delay between the change of differential pressure occurring and the lens element adjustments being applied, and storing information of the identified exposure areas together with the calculated imaging error.