Pellicle Deflection Prediction Model for Lithographic Accuracy
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Solution Overview
Problem
Lithographic errors due to pellicle deflection in lithographic apparatuses are challenging to predict and correct, leading to inefficiencies and increased time in measuring errors, especially when switching between different exposure types like DUV and EUV.
Innovation Solution
A method involving a predictive model that takes into account the properties of the pellicle and its movement, using sub-models to estimate deflection components such as vibrations, inertia, and pressure variations, allowing for preemptive correction of lithographic errors and reduced measurement time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pellicle is attached to the reticle to prevent contamination, then the quality of image projection is improved, but lithographic errors occur due to pellicle deflection during movement
Solution Approach 1:
The patent applies preliminary action by predicting pellicle deflection before the lithographic exposure occurs. A model predicts the deflection based on pellicle properties and expected movement, allowing the system to preemptively determine and correct lithographic errors before they affect the actual exposure, thus maintaining both contamination protection and lithographic accuracy
Solution Approach 2:
The patent implements feedback by using a predictive model that continuously calculates pellicle deflection based on real-time parameters such as pellicle properties, movement characteristics, and environmental conditions. This feedback loop enables dynamic correction of lithographic errors, allowing the system to maintain precision despite the pellicle's presence
2Manufacturing precision
If traditional measurement methods are used to correct pellicle deflection errors, then lithographic accuracy can be maintained, but apparatus availability decreases due to increased measurement time
Solution Approach 1:
The patent performs deflection prediction and error correction in advance before the actual lithographic exposure. By calculating the expected deflection based on pellicle properties and movement parameters beforehand, the system eliminates the need for time-consuming measurements during exposure, thereby maintaining accuracy while improving apparatus availability
Solution Approach 2:
The patent replaces traditional mechanical measurement systems with a computational prediction model. Instead of physically measuring deflection during exposure, the system uses mathematical models that incorporate pellicle properties, movement characteristics, and environmental factors to predict and correct errors, significantly reducing measurement time and improving productivity
3Measurement precision
If measurements are performed for each exposure type (DUV and EUV), then accurate correction is achieved, but the process becomes complex and time-consuming when switching between exposure types
Solution Approach 1:
The patent creates a universal predictive model that can handle multiple exposure types (DUV and EUV) with a single unified approach. The model takes pellicle properties and movement parameters as inputs and generates corrections applicable to different exposure types, eliminating the need for separate measurement procedures for each type and reducing overall system complexity
Solution Approach 2:
The patent manages complexity by dynamically adjusting model parameters based on the specific exposure type and pellicle configuration rather than requiring complete remeasurement. The system modifies relevant parameters such as pellicle properties and movement characteristics to generate accurate predictions for different exposure scenarios, maintaining precision while simplifying the switching process between DUV and EUV modes
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 enables more flexible and efficient lithographic processes by predicting and correcting pellicle deflection, reducing matching errors between different exposure types and improving overall apparatus availability.
Implementation Method 1
the pellicle has a finite thickness and a refractive index which is greater than its environmental gas, for example air, and thus will cause some deflection of any radiation which is not perpendicularly incident upon the pellicle
Data Source
AI summary
A method of predicting deflection of a pellicle which will occur during movement of the pellicle in a lithographic apparatus, the method including receiving parameters regarding properties of the pellicle and receiving parameters regarding the expected movement of the pellicle. The parameters are applied to a model which predicts deflection of the pellicle as a function of those parameters. The model includes a plurality of sub-models which relate to different components of deflection of the pellicle. An output of the model may be used to predict.