Charged Particle Beam Pre-Dose Control for Electrostatic Breakdown Prevention
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Solution Overview
Problem
Existing methods for determining pre-dose conditions in charged particle radiation apparatuses struggle to efficiently raise secondary electrons from deep holes without causing electrostatic breakdown, and current techniques cannot verify the optimal charged state until after the observation beam is scanned, leading to potential damage and inefficiencies in semiconductor inspection.
Innovation Solution
A charged particle radiation apparatus that switches between a first and a second charged particle beam, where the second beam is used for pre-dosing and the control device acquires data to determine the optimal pre-dose conditions by stopping the beam when a predetermined state is reached, preventing electrostatic breakdown and ensuring proper charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sample is excessively charged to raise secondary electrons from deep holes, then the efficiency of secondary electron detection is improved, but electrostatic breakdown occurs causing damage to the sample
Solution Approach 1:
The patent implements a feedback mechanism where the observation beam continuously monitors the charged state of the sample during pre-dosing. The system detects changes in secondary electron emission and automatically adjusts the pre-dose beam conditions or stops irradiation when the optimal charged state is reached, preventing electrostatic breakdown while maximizing secondary electron detection efficiency.
Solution Approach 2:
The patent applies preliminary action by using the observation beam to pre-assess the sample's charged state before applying full pre-dosing. This allows the system to determine safe pre-dose conditions in advance, ensuring that subsequent charging operations will not cause electrostatic breakdown while still achieving sufficient secondary electron emission.
2Measurement precision
If the observation beam is used to verify the pre-dosed state, then the charged state can be determined, but the verification cannot occur until after pre-dosing is complete leading to delayed detection of optimal state
Solution Approach 1:
The patent makes the observation beam perform dual functions continuously: it serves both as the verification tool for charged state detection and as a monitoring tool during pre-dosing. This continuous dual-use eliminates the need to stop pre-dosing for verification, allowing real-time assessment while maintaining the charging process without interruption.
Solution Approach 2:
The observation beam is designed to perform multiple functions simultaneously: it verifies the charged state, monitors for electrostatic breakdown risks, and guides the pre-dosing process. This multi-functionality eliminates the need for separate verification steps and enables continuous operation throughout the pre-dosing sequence.
3Measurement precision
If the pre-dose beam irradiation time is extended to maximize secondary electron emission, then the detection efficiency is improved, but the risk of electrostatic breakdown increases
Solution Approach 1:
The patent implements dynamic control where the pre-dose beam parameters (current, voltage, duration) are continuously adjusted based on real-time feedback from the observation beam. This dynamic adjustment allows the system to extend irradiation time when safe to maximize secondary electron emission, while automatically reducing or stopping irradiation when approaching electrostatic breakdown thresholds, thus maintaining sample integrity.
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 real-time determination of pre-dose conditions, preventing electrostatic breakdown and maximizing secondary electron detection efficiency, thereby enabling precise and efficient measurement and inspection of semiconductor samples without damage.
Implementation Method 1
a beam having a secondary electron emission efficiency (electrons emitted from a sample/electrons incident on the sample) of higher than 1
Implementation Method 2
acquiring signal waveform data or image data of a pattern formed on a sample in accordance with charged particles, which are obtained by scanning a charged particle beam emitted from a charged particle source
Data Source
AI summary
A charged particle radiation apparatus includes a control device that switches between a first charged particle beam and a second charged particle beam, the first charged particle beam being scanned to acquire an image and a waveform signal, the second charged particle beam being scanned over a sample before the scan of the first charged particle beam and used to charge the sample more than the first charged particle beam; wherein the control device is configured to acquire at least one of signal waveform data and image data about a pattern formed on the sample in accordance with a scan performed on the sample by the second charged particle beam, and to stop, when the acquired data has proved to be indicative of a predetermined state, the scan of the second charged particle beam.