Semiconductor Electron Detector With Diode Reset for Low-Current SNR
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Solution Overview
Problem
Current charged particle detection systems, particularly in scanning electron microscopes, face challenges with poor signal-to-noise ratio (SNR) at low electron beam currents, limited durability, and increased complexity due to energy filters, which hinder accurate defect detection in semiconductor manufacturing.
Innovation Solution
A detector system utilizing diodes with integrated voltage monitoring and reset devices, operating in open-circuit mode, and a diode architecture with an avalanche region, allows for efficient electron counting and improved SNR, reducing power consumption and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an amplifier is used to amplify current from the detector, then the detection signal is enhanced, but the power consumption increases and signal-to-noise ratio deteriorates
Solution Approach 1:
The patent removes the amplifier component from the detection system entirely. Instead of using an amplifier to enhance the detection signal, the system directly counts individual electron events using a semiconductor detector connected to a counter, eliminating the source of amplifier noise and its associated power consumption.
Solution Approach 2:
The patent replaces the electronic amplification system with a direct electron counting method. Individual electron events are detected and counted digitally without requiring analog signal amplification, substituting a mechanical/electronic amplification process with a direct digital counting approach.
2Measurement precision
If image averaging or extended integration time is used to improve signal-to-noise ratio, then the detection sensitivity increases, but the electron dose on the sample surface increases causing surface charging artifacts
Solution Approach 1:
The semiconductor detector serves itself by directly counting individual electron events without requiring external signal enhancement techniques. Each electron event is independently detected and counted, providing immediate signal information that eliminates the need for image averaging or extended integration that would otherwise increase electron dose and cause surface charging.
3Measurement precision
If a scintillator and photomultiplier tube are used for particle counting, then good signal-to-noise ratio is achieved at low probe currents, but the scintillator light yield degrades with accumulated electron dose limiting lifetime
Solution Approach 1:
The patent employs a semiconductor detector that is more resistant to radiation damage and has longer operational lifetime compared to scintillator-based systems. The solid-state detector can withstand accumulated electron doses without significant performance degradation, making it suitable for continuous operation in production environments.
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
The solution provides stable quantum efficiency and long lifetime with high SNR, even at low probe currents, and eliminates the need for energy filters, enhancing detection sensitivity and throughput in semiconductor inspection.
Implementation Method 1
a sensing element including a diode; and a circuit configured to detect an electron event caused by an electron impacting the sensing element
Implementation Method 2
a diode architecture with an avalanche region
Data Source
AI summary
A detector may be provided for a charged particle apparatus comprising:a sensing element including a diode; anda circuit configured to detect an electron event caused by an electron impacting the sensing element,wherein the circuit comprises a voltage monitoring device and a reset device,wherein the reset device is configured to regularly reset the diode by setting a voltage across the diode to a predetermined value,and wherein the voltage monitoring device is connected to the diode to monitor a voltage across the diode in between resets.