Multibeam Charged Particle Inspection Apparatus with Independent Energy and Current Control
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Solution Overview
Problem
Conventional multibeam-type and multicolumn-type charged particle beam inspection apparatuses face challenges in freely controlling irradiation conditions such as beam current and incident energy, leading to difficulties in maintaining stable and precise inspection due to fluctuations in field of view and resolution.
Innovation Solution
A charged particle beam applied apparatus with a beam-forming section featuring plural aperture patterns and a control unit that independently controls the incident energy, beam current, and arrangement of charged particle beams, utilizing a beam splitting electrode, lens array, and deflectors to select desired aperture patterns for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of beams is increased to improve inspection speed, then productivity increases, but control of irradiation current and incident energy becomes difficult
Solution Approach 1:
The patent divides the beam control system into multiple independent column systems, each capable of controlling its own beam's irradiation current and incident energy. This segmentation allows each beam to be controlled independently while maintaining high inspection speed through parallel processing of multiple beams simultaneously.
Solution Approach 2:
The patent employs dynamic control mechanisms including variable aperture diaphragms and adjustable lens excitations that can be independently tuned for each beam. These dynamic elements allow real-time adjustment of irradiation conditions for each beam according to specific inspection requirements, maintaining ease of operation despite increased beam count.
2Device complexity
If conventional control methods are used for irradiation current and incident energy, then device complexity is reduced, but field of view and resolution stability deteriorate
Solution Approach 1:
The patent implements feedback control mechanisms where the state of each beam (position, current, energy) is continuously monitored and adjusted. This feedback ensures stable field of view and resolution by compensating for drifts and variations, while the automated nature of the feedback maintains reasonable device complexity through integrated control circuits.
3Measurement precision
If aperture patterns are changed to control beam current, then beam current control precision improves, but device complexity increases
Solution Approach 1:
The patent designs aperture diaphragms that serve multiple functions: controlling beam current through variable aperture sizes, selecting specific beam paths, and defining field of view. This multi-functionality allows precise beam current control without proportionally increasing device complexity, as the same aperture structures perform multiple control tasks simultaneously.
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
Enables high sensitivity and speed in defect detection while maintaining resolution and field of view stability, allowing for flexible adjustment of irradiation conditions.
Implementation Method 1
a beam-forming section forming plural charged particle beams on the sample and including plural aperture patterns having apertures with intervals that are different from each other
Implementation Method 2
a retarding method is generally used in which negative (or positive) voltage is applied to a lens tube of a sample to control energy immediately before irradiation
Implementation Method 3
combinations of the intensities of lenses provided in front of and behind the diaphragm are changed, so that the density of current passing through the diaphragm is controlled
Data Source
AI summary
Provided is a charged particle beam applied apparatus for observing a sample, provided with: a beam-forming section that forms a plurality of charged particle beams on a sample; an energy control unit that controls the incident energy of the plurality of charged particle beams that are irradiated onto the sample; a beam current control unit that controls the beam current of the plurality of charged particle beams that are irradiated onto the sample; and a beam arrangement control unit that controls the arrangement in which the plurality of charged particle beams is irradiated onto the sample. The beam-forming section includes a beam splitting electrode, a lens array upper electrode, a lens array middle electrode, a lens array lower electrode and a movable stage, and functions as the beam current control unit or the beam arrangement control unit through selection, by the movable stage, of a plurality of aperture pattern sets.