Lithography Optics Motion Compensation for Wafer Thermal Deformation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithographic apparatuses using extreme ultraviolet (EUV) radiation suffer from printing errors due to optical aberrations and thermal deformation of the substrate, which distort the image formed on the wafer, leading to degraded optical performance.
Innovation Solution
A method to determine movement parameters for optical elements of the imaging system to correct for thermal deformation of the substrate by dynamically adjusting the image formation process, using models or direct measurements to predict and minimize optical aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the radiation beam is used to expose the substrate, then the image formation is achieved, but thermal deformation of the substrate occurs causing printing errors
Solution Approach 1:
The patent applies preliminary action by determining movement parameters of optical elements before actual exposure occurs. The system calculates required movements based on expected thermal deformation from the radiation beam, and pre-positions optical elements to compensate for upcoming thermal effects, thereby maintaining image accuracy despite thermal deformation.
Solution Approach 2:
The patent implements preliminary anti-action by introducing counteracting movements of optical elements that oppose the expected thermal deformation. The control system determines movement parameters that create compensatory image shifts opposite to the predicted thermal distortion direction, effectively canceling out the harmful thermal effects before they degrade image quality.
2Manufacturing precision
If optical aberrations are present in the projection system, then image distortion occurs on the wafer, but adjusting projection optics requires measurement and correction procedures
Solution Approach 1:
The patent replaces complex mechanical adjustment procedures with a computational approach. Instead of physically measuring and manually adjusting projection optics to correct aberrations, the system uses a control device that calculates movement parameters based on mathematical models of thermal deformation and optical aberrations, then automatically positions optical elements accordingly, substituting mechanical complexity with computational algorithms.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the movement parameters of optical elements based on calculated thermal deformation models. The system varies positional parameters of optical elements in response to changing thermal conditions during exposure, allowing real-time correction of image distortion without complex mechanical intervention.
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
The method reduces printing errors and optimizes imaging performance by canceling thermal distortions of the wafer with a matching distortion of the image, ensuring accurate image formation once the thermal load is removed.
Implementation Method 1
the radiation beam B' used to expose the wafer W may cause (time-dependent) thermal deformation of the wafer W
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A method for determining a value of one or more movement parameters for an imaging system (e.g. of a lithographic apparatus) that is for forming one or more images of an object (e.g. a reticle) on a substrate (e.g. a wafer) using radiation is disclosed. The method comprises: determining a deformation of the substrate due to exposure to the radiation; and determining a value of one or more movement parameters of at least one optical element of the imaging system during the formation of one of the one or more images, the value of the one or more movement parameters being determined in dependence on the determined deformation of the substrate due to the exposure to the radiation (e.g. such that a deformation of the image during the formation of that image at least partially corrects for a deformation of the substrate due to exposure to the radiation).