Charged Particle Beam Static Charge Measurement via Mirror Reflection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing scanning electron beam devices face challenges in accurately measuring samples due to static charges caused by primary charged particle beam irradiation, leading to focusing errors and astigmatisms, which are exacerbated as sample sizes decrease, making it difficult to obtain accurate secondary or reflected electron distribution data.
Innovation Solution
The method involves adjusting the primary charged particle beam to a 'mirror reflection state' where it does not reach the sample surface, allowing for the estimation of localized voltage by analyzing the returned beam, thereby minimizing secondary static charge induction and compensating for beam deviations caused by static charges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the primary charged particle beam irradiates the sample to measure static charge, then static charge quantity can be estimated, but secondary static charge is induced on the sample surface
Solution Approach 1:
The patent introduces a retarding voltage as an intermediary mechanism between the charged particle beam and the sample. By applying retarding voltage to the sample, the primary beam is repelled before reaching the sample surface, acting as a mediator that enables voltage measurement without direct beam-sample contact that would cause secondary charging
Solution Approach 2:
The patent applies retarding voltage to the sample before the primary charged particle beam reaches it. This preliminary application of voltage creates a repulsive field that prevents the beam from contacting the sample surface, thereby measuring the static charge state without inducing additional secondary charges
2Measurement precision
If the primary charged particle beam reaches the sample surface, then secondary electron or reflected electron distribution data can be obtained, but focusing errors and astigmatisms occur due to static charge
Solution Approach 1:
The patent employs a feedback mechanism where the static charge voltage measured through the retarding voltage method is used to adjust and compensate for beam focusing and tracking. The measured voltage information feeds back to correct the beam path and focusing parameters, maintaining reliable beam performance despite the presence of static charges on the sample
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 enables more accurate measurement of localized voltage and reduces the impact of static charges on the charged particle optical system, improving measurement precision and reducing secondary static charge effects, allowing for accurate surface voltage estimation and compensation.
Implementation Method 1
a retarding voltage Vr is applied to a sample 10 and the primary charged particle beam is made to reflect in a mirror state by the retarding voltage
Data Source
AI summary
A charged particle beam device including a function for measuring localized static charges on a sample. A primary charged particle beam scans a sample positioned in a mirror state to acquire an image. The acquired image may be an image of the sample or may be an image of a structural component in the charged particle optical system. The acquired image is compared with a standard sample image and the localized static charge is measured.