Charged Particle Beam Focusing via Astigmatic Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing charged particle beam focusing systems require patterned samples and can introduce aberrations and charging artifacts, limiting their effectiveness in wide area operations and electron beam inspection.
Innovation Solution
A system that generates both astigmatic and non-astigmatic charged particle beams simultaneously, using an aberrating element to introduce astigmatism for focus adjustment, allowing for precise focusing without interrupting normal operation and minimizing aberrations, even in the presence of charging artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If scanning method is used to maximize contrast in scanned image, then focusing can be achieved, but patterned sample with sharp features is required and normal wide area operation is interrupted
Solution Approach 1:
The beam is divided into two separate beams: a first beam used for focus measurement and a second beam used for normal processing operations. This segmentation allows the focus measurement function to be performed independently without interrupting the productive processing operations.
Solution Approach 2:
The focus measurement function is extracted from the main processing beam by using a separate first beam. This extracted measurement beam can operate continuously alongside the processing beam, eliminating the need to interrupt normal operations for focusing.
2Measurement precision
If scanning method is used to maximize contrast, then focusing can be achieved, but charging artifacts are introduced
Solution Approach 1:
By segmenting the beam into a measurement beam and processing beam, the charging artifacts generated by the measurement beam can be isolated from the processing area. The first beam performs focus measurement while the second beam handles processing, separating the harmful charging effects from the productive work area.
3Measurement precision
If stigmator is used to reduce astigmatism, then astigmatism correction is achieved, but additional complexity is introduced to the system
Solution Approach 1:
The system uses the charged particle beam itself to measure and determine focus conditions through the patterns it generates on the substrate. This self-service approach eliminates the need for external stigmator devices or separate focus measurement apparatus, reducing system complexity while maintaining measurement precision.
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
Enables accurate and efficient focusing of charged particle beams on specimens without requiring patterned samples or interrupting normal system operation, while minimizing aberrations and charging artifacts, thus improving the quality of imaging and inspection processes.
Implementation Method 1
a charged particle beam generator, typically an electron beam generator operating in an electron microscope, generates two types of beams simultaneously
Implementation Method 2
The released electrons are received by an imaging detector, which forms images of the locations from the electrons
Data Source
AI summary
A charged particle beam focusing apparatus includes a charged particle beam generator configured to project simultaneously at least one non-astigmatic charged particle beam and at least one astigmatic charged particle beam onto locations on a surface of a specimen, thereby causing released electrons to be emitted from the locations. The apparatus also includes an imaging detector configured to receive the released electrons from the locations and to form images of the locations from the released electrons. A processor analyzes the image produced by the at least one astigmatic charged particle beam and in response thereto adjusts a focus of the at least one non-astigmatic charged particle beam.