Charged Particle Beam Edge Slope Optimization
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Solution Overview
Problem
Charged particle beam lithography faces challenges in achieving accurate and precise pattern transfer due to short-range and long-range effects, leading to dimensional inaccuracies and increased manufacturing variations, particularly as feature sizes approach the resolution limit of optical lithography tools.
Innovation Solution
The method involves calculating and adjusting the edge slope of patterns by increasing the dosage of beamlets in multi-beam charged particle beam writers, allowing for overlapping shots to improve edge slope and accuracy, while maintaining dosages below a target level to manage manufacturing variations and proximity effect corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the dosage of beamlets is increased to improve edge slope and pattern accuracy, then manufacturing precision improves, but manufacturing variations and proximity effects increase
Solution Approach 1:
The patent applies local quality by differentiating dosage levels across different regions of the pattern. Beamlets targeting edges receive enhanced dosage to improve edge slope, while beamlets in other regions maintain standard dosage. This localized dosage adjustment resolves the contradiction by applying increased dosage only where needed for edge accuracy, rather than uniformly across the entire pattern, thereby minimizing the propagation of proximity effects.
Solution Approach 2:
The patent implements partial action by selectively enhancing dosage for specific beamlets that contribute to edge formation, rather than increasing dosage for all beamlets. This partial enhancement achieves the necessary edge slope improvement while limiting the overall increase in manufacturing variations and proximity effects that would result from universal dosage increase.
2Manufacturing precision
If overlapping shots are used to improve edge slope, then pattern accuracy improves, but shot count and exposure time increase
Solution Approach 1:
The patent applies local quality by implementing overlapping shots selectively only in regions where edge slope improvement is needed, rather than applying overlapping shots uniformly across the entire pattern. This localized approach achieves edge slope enhancement while minimizing the overall increase in shot count and exposure time.
Solution Approach 2:
The patent implements partial action by using overlapping shots partially - only for specific beamlets and shots that contribute to edge formation, rather than applying overlapping shots to all pattern elements. This partial application achieves the necessary edge slope improvement while limiting the time penalty associated with comprehensive overlapping shot implementation.
3Productivity
If feature sizes are reduced to approach optical lithography resolution limits, then device density increases, but dimensional accuracy and manufacturing precision deteriorate
Solution Approach 1:
The patent applies parameter changes by modifying the dosage parameter for beamlets exposing small features. By increasing dosage for beamlets targeting edges of reduced-size features, the patent compensates for the reduced signal strength and improved edge slope at smaller dimensions, thereby maintaining manufacturing precision even as device density increases through feature size reduction.
Solution Approach 2:
The patent implements partial action by applying enhanced dosage selectively to beamlets exposing small features and their edges, rather than uniformly increasing dosage for all features. This targeted approach maintains dimensional accuracy for critical small features while avoiding unnecessary dosage increases for larger features, thus supporting higher device density without universal precision degradation.
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 enhances the accuracy and resilience to manufacturing variations, improving critical dimension uniformity, line edge roughness, and line width roughness, while optimizing edge slope to meet 'good enough' standards for practical production purposes, thereby improving the overall precision of pattern transfer in charged particle beam lithography.
Implementation Method 1
charged particle beam lithography is used to transfer patterns to a substrate such as a semiconductor or silicon wafer
Data Source
AI summary
A method and system for fracturing or mask data preparation are presented in which a set of shots is determined for a multi-beam charged particle beam writer. The edge slope of a pattern formed by the set of shots is calculated. An edge of the pattern which has an edge slope below a target level is identified, and the dosage of a beamlet in a shot in the set of shots is increased to improve the edge slope. The improved edge slope remains less than the target level.