Multi-Beam Electron Alignment Using Beam Spot Feedback
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Solution Overview
Problem
Conventional multi-beam electron inspection systems suffer from low inspection accuracy due to misalignments and cross-talk between electron beams, which can be caused by improper alignment of electron optical elements, leading to aberrations and reduced image quality.
Innovation Solution
A particle beam inspection apparatus with an improved alignment mechanism, utilizing a second electron detection device to generate images of secondary electron beam spots and determine alignment characteristics, allowing for real-time adjustments to ensure accurate beam alignment and focus quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-beam electron inspection systems are used to increase inspection speed, then productivity is improved, but misalignments and cross-talk between electron beams occur leading to reduced measurement precision
Solution Approach 1:
The patent implements a feedback mechanism where a second electron detection device continuously monitors beam spot positions and feeds this information back to an alignment control system. This real-time feedback enables dynamic correction of beam misalignments, allowing multi-beam systems to maintain high inspection speed while compensating for alignment drift and cross-talk between beams.
Solution Approach 2:
The patent replaces mechanical alignment adjustment mechanisms with an electronic/optical alignment system. Instead of physically adjusting electron optical elements, the system uses electronic detection of beam positions and software-based correction algorithms to achieve precise beam alignment, thereby maintaining high productivity while improving measurement precision.
2Measurement precision
If electron optical elements are adjusted to improve beam alignment, then measurement precision is improved, but device complexity increases due to additional alignment mechanisms
Solution Approach 1:
The patent implements a self-aligning system where the electron beams automatically indicate their own alignment status through the second electron detection device. The system uses the beam spots themselves as reference markers, eliminating the need for external alignment fixtures or complex mechanical adjustment mechanisms, thereby improving precision without significantly increasing device complexity.
Solution Approach 2:
The patent creates an optical copy or image of the electron beam spots using the second electron detection device. This copied information is then used for alignment verification and correction, allowing the system to monitor and adjust beam alignment without requiring direct physical access to or manipulation of the complex electron optical elements.
3Measurement precision
If real-time beam alignment monitoring is implemented, then measurement precision is improved, but loss of time occurs due to additional detection and processing steps
Solution Approach 1:
The patent merges the inspection function and alignment monitoring function into a single integrated system. The second electron detection device performs both beam spot detection for alignment monitoring and contributes to the overall inspection process, eliminating separate alignment verification steps and reducing time loss while maintaining measurement precision.
Solution Approach 2:
The patent implements continuous beam alignment monitoring throughout the inspection process rather than performing discrete alignment checks. This continuous monitoring allows for real-time correction of alignment drift without interrupting the inspection workflow, thereby maintaining measurement precision while minimizing time loss.
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
Enhances inspection accuracy by reducing misalignments and cross-talk, enabling high-speed, high-precision imaging of micro and nano-sized defects on semiconductor wafers, thereby improving overall yield and throughput in IC chip manufacturing.
Implementation Method 1
a first electron detection device to detect a plurality of secondary electron beams for inspection of the wafer
Data Source
AI summary
An improved charged particle beam inspection apparatus, and more particularly, a particle beam inspection apparatus including an improved alignment mechanism is disclosed. An improved charged particle beam inspection apparatus may include a second electron detection device to generate one or more images of one or more beam spots of the plurality of secondary electron beams during the alignment mode. The beam spot image may be used to determine the alignment characteristics of one or more of the plurality of secondary electron beams and adjust a configuration of a secondary electron projection system.