Multi-Aperture Beam Selector for Uniform Resolution in Inspection
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Solution Overview
Problem
Conventional charged particle multi-beam inspection systems face challenges in achieving uniform resolution and high throughput due to variations in beam quality, with some beams not reaching the object or having deficiencies, which affects the quality of the images obtained.
Innovation Solution
The system employs a multi-aperture plate and a selector to generate and direct multiple primary charged particle beams, allowing for the selection of apertures to ensure that only high-quality beams are imaged onto detection elements, and incorporates scanning strategies to average out differences in beam intensities and focusing properties, thereby improving resolution and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a plurality of primary charged particle beams is directed onto the object using a multi-aperture plate, then the throughput is improved, but the uniformity of resolution deteriorates due to variations in beam quality
Solution Approach 1:
The system divides the beam generation into multiple independent beam paths through the multi-aperture plate, allowing each beam to be individually characterized and managed. This segmentation enables the system to handle beam quality variations by treating each beam as a separate entity that can be evaluated and selected independently.
Solution Approach 2:
The system dynamically changes operational parameters by selecting different combinations of beams and detection elements based on real-time beam quality measurements. The controller adjusts which beams are active and which detection elements receive signals, optimizing the system performance based on actual beam conditions rather than operating with fixed parameters.
2Productivity
If all apertures in the multi-aperture plate are used to generate beams, then the throughput is maximized, but the image quality deteriorates due to deficient beams not reaching the object
Solution Approach 1:
The system implements a feedback mechanism where beam quality is measured for each beam generated by the multi-aperture plate. Based on this feedback information, the controller selectively activates only those beams that meet quality criteria, preventing deficient beams from degrading image quality while maintaining maximum possible throughput with functional beams.
Solution Approach 2:
The system dynamically adjusts which beams are active based on real-time quality assessments. Rather than statically configuring all beams to be always active or all to be inactive, the system flexibly enables or disables specific beams depending on their measured performance, optimizing both throughput and reliability adaptively.
3Productivity
If the number of apertures is increased beyond the number of detection elements, then more beams can be generated for higher throughput, but the system complexity increases
Solution Approach 1:
The multi-aperture plate serves multiple functions: it acts as a beam divider to create multiple primary beams, provides an array of lenses for focusing, and enables dynamic reconfiguration of beam paths. This multi-functionality reduces the need for separate components, managing system complexity while enabling high throughput through multiple beams.
Solution Approach 2:
The controller acts as an intermediary that manages the complexity between the multi-aperture plate and the detection elements. It processes beam quality information, makes selection decisions, and coordinates beam activation with detection element assignment, thereby managing system complexity centrally rather than requiring complex distributed control.
4Productivity
If beams with different intensities and focusing properties are used, then higher throughput is achieved, but the measurement precision deteriorates
Solution Approach 1:
The system compensates for variations in beam intensity and focusing properties by dynamically adjusting operational parameters. The controller selects and combines signals from multiple detection elements in a way that accounts for the specific characteristics of each beam, effectively normalizing the data to achieve uniform resolution despite inherent beam variations.
Solution Approach 2:
The system achieves homogeneous image quality by processing and combining data from multiple beams with different characteristics. Through appropriate signal processing and selection strategies, the system produces a unified image with uniform resolution across the field of view, effectively masking the underlying heterogeneity of individual beam qualities.
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 the production of high-resolution images with improved throughput by ensuring that only high-quality beams contribute to the data, even if some beams have deficiencies, and allows for uniform resolution across the object, particularly beneficial for stitching techniques and three-dimensional imaging.
Implementation Method 1
The multi-aperture plate of the beam generator may have a function of a beam divider which produces the plurality of primary charged particle beams from one single beam having a large diameter which is incident on the multi-aperture plate, wherein particles of the incident beam traversing individual apertures provided in the multi-aperture plate form the plurality of small diameter primary charged particle beams downstream of the multi-aperture plate.
Implementation Method 2
the multi-aperture plate may have a function of providing an array of lenses for the plurality of primary charged particle beams, wherein each charged particle beam traverses one lens and wherein each lens is provided by an aperture of the multi-aperture plate.
Implementation Method 3
charged particle imaging optics configured to image the array of beam spots onto the array of detection elements such that electrons generated by the primary charged particle beams at each beam spot are directed onto a corresponding detection element
Data Source
AI summary
A charged particle multi-beam inspection system comprises a beam generator directing a plurality of primary charged particle beams onto an object to produce an array of beam spots; an array of a first number of detection elements generating detection signals upon incidence of electrons; imaging optics imaging the array of beam spots onto the array of detection elements; wherein the beam generator includes a multi-aperture plate having an array of a second number of apertures greater than the first number; wherein the beam generator includes a selector having plural different states, wherein, in each of the plural different states, the apertures of a different group of apertures are each traversed by one primary charged particle beam, wherein a number of the apertures of the different group of apertures is equal to the first number.