Charged Particle Beam Device High-Frequency Noise Measurement
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Solution Overview
Problem
Current charged particle beam devices, such as scanning electron microscopes, face challenges in measuring high-frequency electrical noise due to the miniaturization of semiconductor processes, which affects the accuracy of electron beam stability and length measurement, and existing methods are inadequate for in-line high-speed measurement of such noise.
Innovation Solution
A charged particle beam device with an electron source, stage, detector, and control unit that continuously irradiates a specific sample portion to calculate the time-series change in electron beam position and determine the frequency spectrum of the beam's shake, enabling high-accuracy measurement of high-frequency electrical noise up to several hundred kHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional scanning methods are used to measure electron beam shake, then measurement can be performed, but high-frequency electrical noise of several hundred kHz or higher cannot be measured due to scanning shake-back time
Solution Approach 1:
The patent extracts the electron beam from the scanning motion and holds it stationary at a specific position on the sample. By eliminating the scanning component, the measurement system can detect high-frequency beam shake up to several hundred kHz without the limitations imposed by scanning shake-back time, thus extending the measurable frequency range.
Solution Approach 2:
The patent employs periodic ON/OFF switching of the electron beam at high speed while the beam is held stationary. This periodic action allows the system to capture high-frequency shake characteristics that would be missed during continuous scanning, enabling measurement of electrical noise in the several hundred kHz range and higher.
2Measurement precision
If scanning is repeated only in X or Y direction to analyze deviation, then frequency characteristics can be obtained, but high-frequency electrical noise of several hundred kHz or higher cannot be measured
Solution Approach 1:
The patent maintains continuous irradiation of a specific sample position by holding the electron beam stationary. This continuous action allows for uninterrupted detection of high-frequency beam shake, enabling the system to capture frequency characteristics up to several hundred kHz without the time losses associated with repeated scanning operations.
3Measurement precision
If a thick electron beam of several micrometers is used for shake measurement, then measurement can be performed, but a thin electron beam diameter of a few nanometers cannot be used
Solution Approach 1:
The patent uses a specific sample position with high secondary electron emission as an intermediary reference point. By holding the thin electron beam stationary at this reference position and detecting secondary electrons, the system can accurately measure beam shake while maintaining the thin beam diameter of a few nanometers, thus preserving manufacturing precision.
4Adaptability or versatility
If switching power supply is used in charged particle beam devices, then device functionality is improved, but electrical noise increases to several hundred kHz affecting electron beam stability
Solution Approach 1:
The patent replaces the conventional scanning mechanical system with a stationary beam holding system. By eliminating the scanning mechanism and holding the electron beam fixed at a specific position, the system can detect high-frequency electrical noise from switching power supplies that would otherwise be masked by scanning motion, enabling identification and mitigation of noise sources affecting beam stability.
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 allows for precise and rapid measurement of high-frequency electrical noise, improving the stability of the electron beam and enabling quick recovery of device performance by identifying and mitigating noise sources, thus enhancing the quality of SEM images.
Implementation Method 1
an electron source configured to generate an electron beam; when the sample is mounted on the stage and a specific portion of the sample is continuously irradiated with the electron beam from the electron source
Implementation Method 2
a detector configured to detect secondary electrons emitted from the sample
Implementation Method 3
the control unit can calculate a time-series change in irradiation position of the electron beam based on an amount of the secondary electrons emitted from the specific portion
Data Source
AI summary
To provide a technique capable of measuring high-frequency electrical noise in a charged particle beam device. A charged particle beam device 100 includes an electron source 2 for generating an electron beam EB1, a stage 4 for mounting a sample 10, a detector 5 for detecting secondary electrons EB2 emitted from the sample 10, and a control unit 7 electrically connected to the electron source 2, the stage 4, and the detector 5 and can control the electron source 2, the stage 4, and the detector 5. Here, when the sample 10 is mounted on the stage 4, and a specific portion 11 of the sample 10 is continuously irradiated with the electron beam EB1 from the electron source 2, the control unit 7 can calculate a time-series change in irradiation position of the electron beam EB1 based on an amount of the secondary electrons EB2 emitted from the specific portion 11, and can calculate a feature quantity for a shake of the electron beam EB1 based on the time-series change in irradiation position. Further, the feature quantity includes a frequency spectrum.