Lithography Beam Profile Control for Thermal Aberration Compensation
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Solution Overview
Problem
Existing lithographic apparatuses face challenges in maintaining optimal operating conditions due to thermal aberrations caused by electromagnetic radiation, which are difficult to compensate without detailed knowledge of the mask's diffraction pattern, a proprietary detail often unavailable to the control system.
Innovation Solution
A method and system that generate control actions for thermal aberration compensation by processing profile information to estimate the diffraction pattern, allowing for accurate control of the lithographic apparatus without requiring detailed mask information, using a beam-shaping device and a programmable mirror array to shape the radiation beam based on encoded mask properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the control system uses a mathematical model to predict wave front errors caused by thermal aberrations, then the accuracy of thermal compensation improves, but the system requires detailed knowledge of the mask which is often proprietary and unavailable
Solution Approach 1:
The patent creates a virtual copy of the mask diffraction pattern by using the known illumination profile and optical system parameters to simulate and estimate the diffraction pattern that would be produced by the actual mask. This estimated diffraction pattern serves as a substitute for the proprietary mask information, allowing the mathematical model to function without direct access to the actual mask details.
Solution Approach 2:
The patent introduces an intermediary estimation process that mediates between the available information (illumination profile, optical parameters) and the required information (mask diffraction pattern). This intermediary step generates the estimated diffraction pattern that bridges the gap between what the control system knows and what the mathematical model needs.
2Manufacturing precision
If the lithographic apparatus operates at high precision for low k1 lithography, then smaller features can be printed, but thermal aberrations from electromagnetic radiation become more significant and harder to control
Solution Approach 1:
The patent applies preliminary anti-action by predicting the thermal aberrations using the mathematical model with the estimated diffraction pattern, and then pre-compensating for these aberrations by adjusting the illumination profile or optical parameters before the actual lithography process. This proactive approach counteracts the thermal effects before they degrade the imaging quality.
Solution Approach 2:
The patent implements a feedback mechanism where the estimated diffraction pattern and predicted wave front errors are used to generate control actions that adjust the illumination system or optical components. This closed-loop control continuously monitors and corrects thermal aberrations to maintain manufacturing precision.
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
Enables more accurate control of thermal aberrations in lithographic apparatuses, improving image fidelity and reducing distortions without needing proprietary mask details, thus enhancing the overall performance and reliability of the apparatus.
Implementation Method 1
the spatial distribution of the electromagnetic radiation on a mirror that reflects an optical image from a mask is generally determined by the diffraction pattern of the mask
Implementation Method 2
Thermal aberration of this kind may be compensated for by selective heating and/or cooling of the optical surfaces
Implementation Method 3
Thermal aberration of this kind may be compensated for by selective heating and/or cooling of the optical surfaces
Data Source
AI summary
A computer-implemented method of generating one or more control actions for controlling a lithographic apparatus. The lithographic apparatus comprises an illumination system for illuminating a mask with a non-uniform radiation beam. The illumination system is configured to receive from a radiation source a radiation beam, and comprising a beam-shaping device configured to receive data specifying profile information, and shape a transverse profile of the radiation beam based on the profile information to form the non-uniform radiation beam. The method comprises processing the profile information to generate an estimated diffraction pattern produced by illuminating the mask with the non-uniform radiation beam, and processing the estimated diffraction pattern to generate one or more control actions for a control system of the lithographic apparatus.