Segmented Aberration Corrector for Electron Beam Trajectory Control
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Solution Overview
Problem
Existing multiple electron beam inspection apparatuses face challenges in correcting aberration and distortion due to high voltage requirements, leading to potential electrical discharges and difficulties in high-speed operation, which affects the accuracy and efficiency of pattern inspection on semiconductor wafers.
Innovation Solution
The apparatus employs an electromagnetic lens with an aberration corrector capable of individually applying bias and deflection potentials to each electron beam, allowing for trajectory correction and focusing onto a target object, thereby reducing aberration and distortion while minimizing voltage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high voltage is applied to the correction electrode of the aberration corrector to correct beam blur, then the correction precision is improved, but electrical discharge occurs at the electrode which causes difficulty in changing potentials at high speed
Solution Approach 1:
The correction electrode is divided into multiple independent electrodes (first correction electrode and second correction electrode) that can be controlled separately. This segmentation allows the system to apply different potentials to different regions, enabling precise correction while distributing the voltage stress to prevent discharge at any single point.
Solution Approach 2:
The patent changes the voltage application strategy by using multiple electrodes with different potentials rather than a single high-voltage electrode. The first correction electrode receives a first potential and the second correction electrode receives a second potential, allowing the system to achieve the same correction effect with lower individual voltages, thereby preventing electrical discharge.
2Area of stationary object
If multiple electron beams are used to extend the field of view, then the inspection area is increased, but beam blur increases due to aberration of the optical system
Solution Approach 1:
The patent segments the correction function into multiple correction electrodes positioned at different locations in the optical path. Each electrode independently corrects aberrations for specific beam regions, allowing the system to maintain tight beam focus across an extended field of view with multiple electron beams.
Solution Approach 2:
The multiple correction electrodes work together to provide universal correction across the entire field of view. The system achieves both extended coverage (multiple beams) and high precision (aberration correction) by having the correction system serve multiple functions simultaneously - correcting chromatic aberration, spherical aberration, and other optical distortions across the expanded inspection area.
3Manufacturing precision
If correction of blur is performed for each beam individually, then the manufacturing precision is improved, but the voltage applied to the correction electrode becomes large causing discharge
Solution Approach 1:
The correction electrode is segmented into multiple independently controllable electrodes. Instead of applying high voltage to a single electrode for each beam, the system distributes the correction function across multiple electrodes, each operating at lower voltage levels, thereby achieving the same precision without electrical discharge.
Solution Approach 2:
The patent merges the correction functions of multiple electrodes working together to achieve the overall beam correction. By combining the effects of several low-voltage electrodes, the system achieves the same trajectory accuracy that would require a single high-voltage electrode, but without the risk of electrical discharge.
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 solution enables high-speed and accurate correction of electron beam trajectories, reducing aberration and distortion, and preventing electrical discharges, thus enhancing the inspection process's efficiency and accuracy.
Implementation Method 1
an electromagnetic lens configured to refract multiple electron beams incident
Implementation Method 2
an objective lens configured to focus the multiple electron beams
Implementation Method 3
configured to be able to individually apply a bias potential and a deflection potential to each of the multiple electron beams
Data Source
AI summary
A multiple electron beam irradiation apparatus includes an electromagnetic lens configured to refract multiple electron beams incident, an aberration corrector arranged in the magnetic field of the electromagnetic lens and configured to be able to individually apply a bias potential and a deflection potential to each of the multiple electron beams, and an objective lens configured to focus the multiple electron beams, a trajectory of the each of which has been individually corrected by the bias potential and the deflection potential, onto a target object.