Scanning Electron Microscope Angle-Resolved Secondary Electron Detection
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Solution Overview
Problem
Conventional charged particle beam devices struggle to accurately determine step patterns, particularly those with combinations of materials for grooves and projections, leading to ineffective pattern alignment.
Innovation Solution
A scanning electron microscope is designed with a detection unit comprising a first and second detector to capture secondary electrons at specific angles, calculating a ratio between their signals to determine step patterns regardless of material combinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If difference operation is performed on images from two or more detectors to determine edge regions, then pattern alignment can be performed, but step patterns with certain material combinations cannot be properly determined
Solution Approach 1:
The invention changes the detection parameter from simple image intensity difference to secondary electron emission angle. By detecting secondary electrons at different emission angles (first detection unit for smaller angles, second detection unit for larger angles) and calculating the ratio between their signals, the system can determine step patterns regardless of material combinations, as the angle-dependent emission characteristics are more universal across materials than intensity differences
Solution Approach 2:
The invention adds a new dimension to the detection by introducing angle-resolved secondary electron detection. Instead of only analyzing intensity differences in the image plane, the system now incorporates the emission angle dimension by using multiple detectors positioned at different angles, creating a ratio image that encodes both intensity and angular information for more robust step pattern determination
2Loss of information
If at least two detectors are used to detect charged particles, then more information can be obtained for image processing, but the device complexity increases
Solution Approach 1:
The detection system is segmented into two specialized detection units, each optimized for detecting secondary electrons at specific emission angles. This segmentation allows the system to capture angle-resolved information without requiring a single complex detector, as each unit has a simpler, more focused function
Solution Approach 2:
The ratio image obtained from the two detectors serves multiple functions: it enables step pattern determination, provides material-independent analysis, and works for various material combinations. This multi-functionality compensates for the added detector complexity by delivering versatile information that solves multiple measurement challenges
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 precise determination of step patterns, improving pattern alignment and material-independent analysis.
Implementation Method 1
a beam source that irradiates a primary electron beam
Implementation Method 2
a detection unit that detects secondary electrons generated from a measurement object by irradiation of the primary electron beam to the measurement object
Data Source
AI summary
A scanning electron microscope capable of properly determining a step of a step pattern formed on a sample regardless of combination of material of a groove of the step pattern and material of a projection of the step pattern, the scanning electron microscope includes a beam source, a detection unit having a first detection unit that detects a secondary electron emitted from the sample at an angle between an optical axis direction of the primary electron beam which is equal to or less than a predetermined value, and a second detection unit that detects a secondary electron emitted from the sample at an angle between the optical axis direction of the primary electron beam which is greater than the predetermined value, and a processing unit to obtain information on the step pattern using the information on a ratio between signals outputted from the first and the second detection unit.