Laser Parameter Determination for Photolithographic Mask Error Correction
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Solution Overview
Problem
Current methods for correcting errors in photolithographic masks and templates lack a quantitative description of the effects caused by laser beams, making it difficult to accurately determine the necessary parameters for error correction in nanoimprint lithography.
Innovation Solution
A method is developed to determine unknown laser beam parameters by inducing persistent modifications in the material, measuring these modifications, and using a deformation model to calculate the required parameters, allowing for precise correction of errors in photolithographic masks and templates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a library of pixel arrangements is used for error correction, then some errors can be corrected, but the process requires significant effort and lacks quantitative description of laser beam effects
Solution Approach 1:
The patent applies parameter changes by systematically varying laser beam parameters (energy, pulse duration, repetition rate, numerical aperture, focus size) to create different pixel configurations in the transparent material. This allows quantitative control over the correction process rather than relying on pre-defined libraries, directly resolving the contradiction between correction capability and process complexity
Solution Approach 2:
The patent implements feedback by measuring the actual displacement errors in the mask or template, using these measurements to calculate the required pixel arrangement and laser parameters, then applying the correction and verifying the result. This closed-loop approach eliminates the need for extensive pre-computed libraries while ensuring accurate correction
2Manufacturing precision
If femtosecond laser pulses are used to create local density variations, then pattern element displacements are achieved, but the quantitative relationship between laser parameters and correction effects is unknown
Solution Approach 1:
The patent replaces the trial-and-error mechanical approach with a physics-based model that calculates the relationship between laser beam parameters and the resulting pixel characteristics. This theoretical model substitutes empirical experimentation with deterministic calculation, recovering the lost information about parameter effects through scientific principles
Solution Approach 2:
The patent systematically investigates how changes in laser beam parameters (energy, pulse duration, repetition rate, numerical aperture, focus size) affect pixel size, density, and resulting displacement. This parameter study establishes the quantitative relationships that were previously unknown, enabling precise control of manufacturing precision
3Manufacturing precision
If photolithographic masks are manufactured with higher resolution, then smaller structures can be projected, but the manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent applies preliminary action by correcting errors in the mask or template after fabrication but before use. By measuring and correcting displacement errors at this stage, the method prevents the need to re-manufacture entire masks, thereby reducing overall manufacturing complexity and cost while maintaining high projection resolution
Solution Approach 2:
The patent implements local quality by applying corrections only to specific regions of the mask or template where errors are detected, rather than re-manufacturing the entire component. The laser beam creates localized pixel modifications precisely where needed, reducing waste and simplifying the manufacturing process
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 direct correction of measured errors in photolithographic masks and templates, increasing the yield of the fabrication process by allowing for accurate control of laser beam parameters, including pixel arrangement and optical transmission modifications.
Implementation Method 1
the laser source applies a huge local energy density on the transparent material of a substrate of a photolithographic mask or of a template which leads to a local melting of the transparent material
Implementation Method 2
The generation of pixels in a transparent material by high intensity femtosecond light pulses induces a local nonlinear optical process at the interaction zone of the photons of the light pulses with the electrons of the material
Data Source
AI summary
The invention relates to a method for determining at least one unknown laser beam parameter of a laser beam used for correcting errors of a transparent material including inducing a first persistent modification in the material by an interaction with the laser beam having a first set of laser beam parameters, measuring the induced first persistent modification of the material, calculating a second persistent modification in the material using a model describing persistent modifications in the material with a second set of laser beam parameters, wherein the first set of laser beam parameters comprises the second set of laser beam parameters and the at least one unknown laser beam parameter, setting up a target functional including the first persistent modification and the second persistent modification, and determining the at least one unknown laser beam parameter by minimizing the target functional.