Multi-Beam SEM Common and Individual Optics for Wafer Inspection
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Solution Overview
Problem
Current multi-beam electron microscopes face challenges in efficiently scanning and inspecting semiconductor wafers due to limitations in beam spacing, individual beam corrections, and overlap issues, which affect throughput and image quality in high-resolution imaging.
Innovation Solution
A multi-beam scanning electron microscope with a multi-beam emitter, common and individual electron beam optics, and a detection assembly that allows for simultaneous inspection of multiple beams with improved beam separation and focusing, enabling high-resolution imaging and efficient data collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single column with an array of beams is used, then a high number of beams can be used for fast wafer inspection, but individual corrections of the beams become difficult
Solution Approach 1:
The patent divides the beam control system into common optics for all beams and individual optics for each beam. The common objective lens assembly focuses all beams simultaneously, while individual objective lenses provide beam-specific corrections. This segmentation allows maintaining high productivity through parallel multi-beam operation while enabling individual beam corrections when needed.
Solution Approach 2:
The common objective lens assembly serves multiple functions: it provides primary focusing for all beams and enables parallel inspection of multiple areas. Individual objective lenses supplement this with beam-specific corrections. This multi-functional design achieves both high throughput and individual beam control capability.
2Measurement precision
If electron beams are focused with high resolution, then spatial resolution is improved, but electron-electron interaction and overlap effects increase
Solution Approach 1:
The patent uses individual objective lenses for each electron beam to provide independent focusing and control. This segmentation allows optimizing focus for each beam separately, maintaining high spatial resolution while minimizing overlap between beams. The separate control paths reduce electron-electron interactions by allowing independent beam positioning and timing.
Solution Approach 2:
Each electron beam is given individual optical elements with properties optimized for its specific requirements. This local quality approach allows each beam to achieve optimal focus and positioning without being constrained by uniform system-wide settings, thereby maintaining high resolution while reducing harmful interactions through customized beam parameters.
3Productivity
If multiple beams are scanned simultaneously, then throughput is improved, but beam separation and overlap control become more difficult
Solution Approach 1:
The patent employs individual scanning deflectors for each electron beam, allowing independent scanning control. This segmentation enables simultaneous scanning of multiple beams across different regions with customized scan patterns, achieving high throughput while maintaining precise beam separation. Each beam's scan parameters can be independently optimized to avoid overlap.
Solution Approach 2:
The patent utilizes multiple spatial dimensions and temporal sequencing for beam separation. Beams are separated not only in space through individual deflectors but also in time through synchronized scanning sequences. This multi-dimensional approach allows simultaneous operation of multiple beams while maintaining clear separation and avoiding overlap.
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
The solution enhances throughput and image quality by allowing individual beam control and separation, reducing electron-electron interaction, and minimizing overlap effects, thereby improving the scanning efficiency and resolution of semiconductor wafer patterns.
Implementation Method 1
a multi-beam emitter for emitting a plurality of electron beams
Implementation Method 2
a common objective lens assembly for focusing the plurality of electron beams... adapted for focusing the plurality of electron beams onto a specimen
Data Source
AI summary
A multi-beam scanning electron beam device (100) is described. The multi-bea scanning electron beam device having a column, includes a multi-beam emitter (110) for emitting a plurality of electron beams (12,13,14), at least one common electron beam optical element (130) having a common opening for at least two of the plurality of electron beams and being adapted for commonly influencing at least two of the plurality of electron beams, at least one individual electron beam optical element (140) for individually influencing the plurality of electron beams, a common objective lens assembly (150) for focusing the plurality of electrons beams having a common excitation for focusing at least two of the plurality of electron beams, and adapted for focusing the plurality of electron beams onto a specimen (20) for generation of a plurality of signal beams (121, 131,141), and a detection assembly (170) for individually detecting each signal beam on a corresponding detection element.