Charged Particle Beam Control Device Noise Subtraction
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Solution Overview
Problem
Existing charged particle beam control devices face challenges in accurately detecting signals from deep grooves or holes in semiconductor patterns due to noise interference, particularly in signal wiring between detectors and amplifier circuits, which reduces the signal-to-noise ratio and measurement accuracy.
Innovation Solution
A charged particle beam control device configuration that includes a detector for secondary electrons, signal wiring for electric signals, noise detection wiring for noise signals, and an arithmetic circuit to subtract noise signals from the electric signals, with a termination circuit adjusting impedance to equalize noise and signal wiring noise levels, and optional noise waveform adjustment circuits to refine noise removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a main detector is used to detect secondary electrons from deep grooves or holes, then the detection signal is obtained, but the noise generated in the device mixes in the signal wiring and reduces the signal-to-noise ratio
Solution Approach 1:
The detection system is segmented into two separate detection paths: one for the main signal (secondary electrons from the sample) and one for noise detection. The noise detection wiring is physically separated from the signal wiring to independently detect noise components generated in the device, allowing subsequent noise removal through arithmetic operations.
Solution Approach 2:
A dedicated noise detection wiring acts as an intermediary that specifically detects noise signals generated in the device without carrying the main detection signal. This intermediary path allows the noise component to be separately identified and subtracted from the main signal, improving the overall signal-to-noise ratio.
2Object-affected harmful factors
If the detection circuit uses an antenna to detect electromagnetic wave noise, then electromagnetic noise is removed, but noise in the signal wiring between the detector and amplifier circuit cannot be removed
Solution Approach 1:
The approach changes from detecting electromagnetic waves in the air (antenna method) to directly detecting electrical noise signals in the signal wiring itself. By placing the noise detection wiring in parallel with the signal wiring, the system detects noise at the electrical signal level rather than the electromagnetic wave level, enabling removal of noise that mixes in the wiring.
Solution Approach 2:
The noise detection wiring creates a copy of the signal wiring path to detect noise components. By having a parallel detection path that mirrors the signal path, the system can detect the same noise components that affect the main signal, allowing for accurate noise subtraction.
3Measurement precision
If electrons are emitted from the bottom of deep grooves or holes, then dimension measurement data is obtained, but most electrons collide with side surfaces and are scattered reducing detection amount
Solution Approach 1:
The system uses feedback by detecting noise components and feeding this information back to the arithmetic circuit for noise removal. This feedback mechanism allows the system to compensate for the weak detection signal by actively subtracting noise components, effectively improving the signal-to-noise ratio even when the detection signal is weak due to electron scattering.
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 significantly improves signal detection accuracy by effectively removing noise from the signal wiring, maintaining high signal detection precision even in deep features, and reducing noise interference.
Implementation Method 1
a detector that detects secondary electrons emitted from a sample by irradiating the sample with a charged particle beam and outputs an electrical signal based on the detected secondary electrons
Data Source
AI summary
Provided is a charged particle beam control device having improved signal detection accuracy. The charged particle beam control device (detection block) includes: a detector provided in a charged particle beam device, and configured to detect secondary electrons emitted from a sample by irradiating the sample with a charged particle beam and output an electric signal based on the detected secondary electrons; a signal wiring configured to transmit the electric signal; a noise detection wiring configured to detect a noise signal generated in the charged particle beam device; and an arithmetic circuit configured to generate a signal obtained by subtracting the noise signal from the electric signal.