Charged Particle Beam Aperture Control for Nanometer Resolution
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Solution Overview
Problem
The apparent beam width (ABW) of existing charged particle beam devices, such as CD SEM systems, limits their ability to measure line widths below 10 nm due to factors like beam divergence, diffraction, and limited depth of field, making it difficult to accurately inspect and structure specimens at the micrometer and nanometer scale.
Innovation Solution
A charged particle beam device with an optical aberration correction device and an objective lens system that adjusts the beam aperture angle to reduce diffraction, combined with a tilting device that tilts the beam by an angle equal or less than the corrected beam aperture angle, improving the beam spot size and reducing blur caused by beam divergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the beam aperture angle is increased to reduce diffraction, then measurement precision improves, but beam divergence increases causing blur and reducing manufacturing precision
Solution Approach 1:
The patent applies dynamics by making the beam aperture angle adjustable rather than fixed. The system can dynamically change the beam aperture angle depending on the measurement or structuring task, allowing optimization between reducing diffraction (larger angle) and minimizing beam divergence blur (smaller angle) based on real-time requirements
Solution Approach 2:
The patent changes the parameter of beam aperture angle to resolve the contradiction. By adjusting this parameter, the system can optimize the balance between diffraction reduction (improving measurement precision) and beam divergence control (maintaining manufacturing precision) for different application scenarios
2Measurement precision
If the beam spot size is reduced to improve resolution, then measurement precision improves, but the beam becomes more susceptible to diffraction and beam divergence
Solution Approach 1:
The system dynamically adjusts the beam aperture angle based on the desired beam spot size and measurement requirements. When a smaller beam spot size is needed for higher resolution, the system can increase the beam aperture angle to compensate for increased susceptibility to diffraction and beam divergence effects
Solution Approach 2:
The patent changes multiple parameters including beam aperture angle and tilt angle to optimize the beam characteristics. By adjusting these parameters, the system can achieve small beam spot sizes for high resolution while compensating for the increased effects of diffraction and beam divergence
3Measurement precision
If optical aberration correction is applied to reduce diffraction, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent corrects optical aberrations by adjusting parameters of the objective lens device and introducing a beam tilt angle. This approach to reducing diffraction and improving measurement precision avoids the need for additional complex correction devices, thereby limiting the increase in device complexity
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 configuration allows for the achievement of beam spot sizes as small as 1 nm, enhancing the capability to measure and structure specimens with improved resolution and accuracy, particularly in semiconductor manufacturing and nanometer-scale inspections.
Implementation Method 1
defining a corrected beam aperture angle adjusted to reduce diffraction
Implementation Method 2
reducing blur caused by beam divergence
Data Source
AI summary
A charged particle beam device is provided, including: a charged particle beam source adapted to generate a charged particle beam on an axis; an optical aberration correction device and an objective lens device, which define a corrected beam aperture angle adjusted to reduce diffraction; and a charged particle beam tilting device; wherein the optical aberration correction device and the objective lens device are adapted to provide the charged particle beam with a beam aperture angle smaller than the corrected beam aperture angle; and wherein the charged particle beam tilting device is adapted to provide a beam tilt angle which is equal or less than the corrected beam aperture angle. Further, a method of operating a charged particle beam device is provided.