EUV Mask Writing Positional Deviation Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in the EUV mask writing process is maintaining cleanliness and achieving precise positional accuracy due to the complexity of sub-resolution assistant features and the difficulty in managing particles caused by resist residues, especially when using electrostatic chucks, which can lead to positional deviations and image quality issues.
Innovation Solution
A method and apparatus that measure the topography of the substrate's backside without gravity sag influence, calculate positional deviations, and correct them using approximate expressions and coefficients, allowing for precise pattern writing on the frontside without relying on electrostatic chucks, thereby maintaining cleanliness and improving reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrostatic chucks are used to hold EUV masks, then positional accuracy can be maintained, but particle contamination and cleanliness issues arise due to resist residues
Solution Approach 1:
The patent extracts the mask holding function from the electrostatic chuck system and implements it through a three-point support mechanism. This separation removes the source of particle contamination (electrostatic chuck surface) while preserving the essential function of positional stability during mask writing and inspection processes
Solution Approach 2:
The patent introduces a three-point support mechanism as an intermediary between the mask and the writing/inspection system. This mediator provides stable positional reference without the contamination issues of direct electrostatic chuck contact, enabling clean mask handling while maintaining precision
2Manufacturing precision
If sub-resolution assistant features are added to correct optical proximity effects, then pattern accuracy improves, but writing time and pattern complexity increase
Solution Approach 1:
The patent performs preliminary topography measurement and gravitational deformation calculation before the actual mask writing process. By pre-determining the deformation characteristics and establishing correction algorithms in advance, the system can efficiently compensate for distortions without adding excessive writing time during production
Solution Approach 2:
The patent implements a feedback mechanism where topography measurement data is used to calculate gravitational deformation, which then feeds into the writing correction process. This closed-loop approach allows the system to automatically adjust writing parameters based on measured deformations, improving pattern accuracy without manual intervention
3Measurement precision
If backside topography is measured without gravity sag influence, then positional deviation calculation accuracy improves, but measurement and correction process complexity increases
Solution Approach 1:
The patent performs preliminary topography measurement to capture the mask backside shape before gravitational deformation occurs during holding. By measuring and recording the undeformed state in advance, the system can accurately calculate positional deviations without needing to physically eliminate gravity effects during measurement
Solution Approach 2:
The patent replaces physical mechanical correction of gravitational deformation with computational correction algorithms. Instead of mechanically supporting the mask to eliminate gravity sag, the system uses topography data and mathematical models to calculate and compensate for positional deviations in the writing process
Data Source
AI summary
A charged particle beam writing method includes measuring a topography of a backside of a substrate without an influence of a gravity sag, calculating a first positional deviation amount of a pattern written on a frontside of the substrate in a case of the backside of the substrate having been corrected to be flat, based on the the backside topography of the substrate, calculating a first coefficient of a first approximate expression indicating a positional deviation correction amount for correcting the first positional deviation amount, based on the first positional deviation amount, adding the first coefficient to a second coefficient of a second approximate expression indicating a positional deviation correction amount for correcting a second positional deviation amount of the pattern written on the frontside of the substrate in a case of the backside of the substrate having not been corrected to be flat, and writing the pattern on the frontside of the substrate utilizing a charged particle beam, based on one of a positional deviation correction amount obtained by a third approximate expression indicating a positional deviation correction amount using a third coefficient obtained as a result of the adding, and the positional deviation correction obtained by the second approximate expression.