Sensing Element Counting Circuitry for Low-Current Electron Detection
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Solution Overview
Problem
Existing detection systems for charged particle beam tools face challenges with signal-to-noise ratio (SNR) and system throughput, particularly at low beam currents, due to the stochastic nature of electron arrival events, leading to high miscounting rates.
Innovation Solution
The implementation of a detector with a layer of circuitry configured for charged particle counting, including an analog pipeline and multiple converters, to temporarily store and process signals related to electron arrival events, reducing miscounting and improving processing rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If basic circuitry is used for electron counting, then the detector can count charged particles, but the miscounting rate becomes high due to the stochastic nature of electron arrival events
Solution Approach 1:
The detector is divided into multiple sensing elements arranged in an array, with each sensing element having dedicated circuitry for charged particle counting. This segmentation allows independent processing of electron arrival events at each sensing element, reducing miscounting caused by stochastic electron arrival by distributing the counting burden across multiple independent channels rather than using a single basic circuitry system.
2Measurement precision
If lower beam currents are used for miniaturized semiconductor inspection, then the signal-to-noise ratio improves, but the system throughput decreases
Solution Approach 1:
The detector enables continuous electron counting operation by implementing circuitry that can process electron arrival events in real-time without requiring interruption or averaging. Each sensing element continuously monitors and counts individual electron arrivals, maintaining high signal-to-noise ratio at low beam currents while sustaining system throughput through uninterrupted detection operation.
3Measurement precision
If electron counting is implemented to enhance signal-to-noise ratio at low beam currents, then measurement precision improves, but the complexity of the detection system increases
Solution Approach 1:
The circuitry implemented in each sensing element is designed to perform multiple functions: detecting electron arrivals, counting individual events, and processing signals. This multi-functional design reduces overall system complexity by eliminating the need for separate dedicated circuits for each function, while still achieving enhanced signal-to-noise ratio through electron counting capability.
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 enhances the ability of the detector to accurately count charged particles, improve signal-to-noise ratio, and increase throughput, even at low beam currents, while reducing miscounting rates.
Implementation Method 1
a sensing element configured to generate a signal in response to a charged particle event
Data Source
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AI summary
A charged particle beam detector may include a circuit with a storage cell configured to receive a signal representing an output of a sensing element; a storage cell multiplexer configured to selectively transmit the signal representing the output of the sensing element to the storage cell; a threshold detector configured to compare the signal representing the output of the sensing element to a threshold; and a converter configured to perform signal processing on a signal transmitted from the storage cell.