Pattern Data Alteration for Lithographic Aberration Compensation
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Solution Overview
Problem
Conventional lithographic systems face errors in feature formation due to aberrations and distortions in projection systems and non-uniformities in illumination, which are not adequately compensated by existing rasterization techniques.
Innovation Solution
A method and system that measure and alter pattern data to account for aberrations and distortions in the projection system, as well as non-uniformities in the illumination field and pupil, to generate corrected control signals for individually controllable elements in the patterning device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional rasterization techniques are used, then the lithographic system can operate with standard optical elements, but aberrations and distortions cause errors in feature formation
Solution Approach 1:
The patent applies preliminary action by pre-characterizing the optical system's aberrations and distortions through measurement, then using this characterization data to correct pattern data before lithographic exposure. This allows the system to compensate for optical imperfections in advance, improving feature formation accuracy without requiring complex real-time corrections during exposure.
Solution Approach 2:
The patent changes parameters by measuring actual optical characteristics (aberrations, distortions, illumination uniformity) and using these measured parameters to adjust and correct the pattern data. This transforms the static rasterization process into a dynamic one that adapts to the specific optical system's characteristics, thereby improving manufacturing precision.
2Manufacturing precision
If perfect optical elements are assumed in rasterization, then the computational process is simplified, but actual optical imperfections cause image formation errors
Solution Approach 1:
The patent replaces the mechanical/optical approach of using perfect optical elements with a computational approach. Instead of relying on physically perfect optics, the system uses measured optical characteristics to computationally correct pattern data, substituting physical perfection with informational correction.
Solution Approach 2:
The patent implements feedback by measuring the actual optical characteristics of the projection system and using this feedback information to correct subsequent pattern data. The measured aberrations and distortions feed back into the rasterization process, allowing the system to continuously compensate for optical imperfections.
3Manufacturing precision
If uniform illumination is assumed, then the rasterization algorithm is simpler, but illumination non-uniformities cause errors in the formed features
Solution Approach 1:
The patent changes the illumination parameter from an assumed uniform distribution to an actually measured non-uniform distribution. By characterizing the real illumination profile and using this information to adjust pattern data, the system compensates for illumination non-uniformities and improves feature uniformity across the substrate.
Data Source
AI summary
A system and method are used to compensate for distortions or aberrations in an image formed in a projection system. Pattern data is generated corresponding to features to be formed on a substrate. At least one of aberrations and distortions of a projection optical system are measured. The pattern data is altered based on the measuring step. The altered pattern data is transmitted to a patterning device to control individually controllable elements coupled to the patterning device. Non uniformities in one or both of a field and pupil of an illumination system can also be measured and used to alter the pattern data.