Detector Array Signal Decoupling for Electron-Beam Cross Talk
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Solution Overview
Problem
Existing charged particle-optical systems face challenges in reducing cross talk between detection signals from different areas of a sample, which affects the accuracy of defect inspection and metrology in semiconductor manufacturing.
Innovation Solution
A charged particle-optical apparatus and method that includes a controller to determine cross talk values by analyzing detection signals from subsets of primary beams and then reduces cross talk by operating on the detection signals using these determined values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If apertures are narrowed to reduce cross talk, then cross talk is reduced, but the amount of collected electrons is reduced
Solution Approach 1:
The patent segments the detection process by assigning specific detector elements to specific probe beams, creating a one-to-one correspondence between beam-aperture-detector triplets. This segmentation allows each detector element to exclusively detect electrons from its associated aperture, preventing cross talk while maintaining full aperture opening for maximum electron collection.
Solution Approach 2:
The patent introduces an intermediary mapping relationship between probe beams, apertures, and detector elements. By establishing this intermediary correspondence, the system allows wide apertures to collect electrons while ensuring that only the intended detector element receives electrons from each aperture, thus reducing cross talk without narrowing apertures.
2Productivity
If multiple probe beams are used simultaneously to speed up assessment, then productivity is improved, but cross talk between neighboring probe beams increases
Solution Approach 1:
The patent segments the detection system into multiple independent beam-detector channels, where each probe beam has its own dedicated detector element. This segmentation enables simultaneous operation of multiple beams without cross talk interference, as each detector exclusively monitors its associated beam's electrons, thus maintaining both high productivity and signal accuracy.
Solution Approach 2:
The patent establishes an intermediary mapping between multiple probe beams and multiple detector elements, creating distinct detection pathways for each beam. This intermediary relationship allows parallel processing of multiple beams while preventing signal mixing, thereby achieving both high productivity through parallel assessment and high measurement precision through isolated detection channels.
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 effectively reduces cross talk without significantly decreasing the overall signal strength, thereby improving the accuracy and throughput of defect inspection and metrology processes.
Implementation Method 1
Collecting interaction products that result from the interaction of the primary beam with the part of the substrate, allows the electron microscope to collect data representing the probed part of the substrate. The interaction products may contain charged particles which may be referred to as signal particles (e.g. signal electrons), such as secondary electrons and backscattered electrons
Implementation Method 2
The interaction products may contain charged particles which may be referred to as signal particles (e.g. signal electrons), such as secondary electrons and backscattered electrons
Implementation Method 3
a charged particle-optical device configured to direct a plurality of beams of charged particles along respective beam paths toward a sample
Data Source
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AI summary
A charged particle-optical apparatus is configured to direct charged particles toward a sample. A charged particle-optical device is configured to direct a plurality of beams of charged particles along respective beam paths toward a sample. A detector array of detector elements is configured to detect signal charged particles emitted from respective areas of a surface of the sample so as to generate respective detection signals. A controller is configured to determine cross talk values indicative of proportions of each detection signal resulting from the detector element detecting signal charged particles emitted from areas other than its respective area. The controller is configured to reduce cross talk by operating on the detection signals using the determined cross talk values based on signals resulting from subsets of the primary beams on the sample.