Charged Particle Beam Lithography Edge Slope Optimization
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Solution Overview
Problem
Charged particle beam lithography faces challenges in achieving accurate pattern transfer due to short-range and long-range effects, leading to dimensional inaccuracies and increased complexity in reticle manufacturing, particularly when dealing with sub-wavelength features and high circuit density in integrated circuits.
Innovation Solution
The method involves generating overlapping shots with varying dosages and sizes to improve the fidelity and critical dimension variation of the pattern, using simulation to determine the optimal shot placement and dosage distribution, which can enhance edge slope and reduce backscatter effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional charged particle beam lithography is used to transfer patterns, then the manufacturing process can be completed, but dimensional inaccuracies occur due to short-range and long-range effects
Solution Approach 1:
The patent applies preliminary action by pre-calculating and applying proximity effect corrections to the shot dosages before the actual pattern writing process. The system computes correction factors based on the expected backscatter and forward scatter effects, then adjusts the dosage of each shot in advance to compensate for these anticipated distortions, thereby achieving accurate pattern dimensions despite the inherent physical effects
Solution Approach 2:
The patent implements feedback through an iterative simulation and optimization process. The system simulates the charged particle beam interactions with the resist and substrate, measures the resulting pattern distortions, and uses this information to refine and adjust the shot dosages and parameters. This closed-loop approach continuously improves pattern accuracy by learning from simulated or measured outcomes
2Manufacturing precision
If overlapping shots with varying dosages are used to improve pattern accuracy, then manufacturing precision improves, but device complexity increases
Solution Approach 1:
The patent applies local quality by assigning different dosages and parameters to different shots based on their specific location and role in the pattern. Rather than using a uniform approach, the system tailors each shot's characteristics (dosage, size, overlap) to its local requirements, with shots in different regions having optimized parameters to achieve the desired pattern fidelity while managing overall complexity
Solution Approach 2:
The patent employs parameter changes by systematically varying shot dosages, sizes, and overlap parameters to optimize pattern formation. The system adjusts these parameters based on the local pattern geometry, material properties, and expected scattering effects, transforming a complex multi-parameter optimization problem into a manageable process through simulation-guided parameter selection
3Manufacturing precision
If higher dosages are applied to improve edge slope, then pattern definition improves, but backscatter effects increase causing more dimensional inaccuracies
Solution Approach 1:
The patent applies parameter changes by optimizing the shot dosage and size parameters to achieve the desired edge slope while minimizing backscatter. The system simulates different dosage scenarios and selects parameters that produce sharp edges without excessive backscatter, rather than simply increasing dosage uniformly
Solution Approach 2:
The patent converts the harmful backscatter effect into a beneficial tool by deliberately using overlapping shots where the backscatter from one shot contributes to the proper exposure of adjacent regions. The system calculates and exploits these interactions to achieve uniform pattern formation, turning what would normally be a source of distortion into a mechanism for improving pattern fidelity
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 improves the accuracy and edge slope of the pattern transferred to the surface, reducing critical dimension variation and manufacturing errors, while maintaining or reducing the overall writing time and cost.
Implementation Method 1
charged particle beam lithography is used to transfer patterns to a substrate
Implementation Method 2
expose a resist-coated surface with these simple shapes
Implementation Method 3
overlapping shots are generated to increase dosage in selected portions of a pattern
Implementation Method 4
reduce backscatter effects
Implementation Method 5
short-range and long-range effects
Data Source
AI summary
A method and system for fracturing or mask data preparation are presented in which overlapping shots are generated to increase dosage in selected portions of a pattern, thus improving the fidelity and/or the critical dimension variation of the transferred pattern. In various embodiments, the improvements may affect the ends of paths or lines, or square or nearly-square patterns. Simulation is used to determine the pattern that will be produced on the surface.