Multi-Beam Sample Scanning to Limit Thermal Distortion
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Solution Overview
Problem
Existing charged-particle inspection tools face challenges in maintaining throughput and position accuracy due to thermal loads applied on samples, which can cause distortion and reduce yield in semiconductor manufacturing.
Innovation Solution
A method using a multi-beam of charged particles is employed, where the sample is moved in a specific direction while the multi-beam is scanned in a perpendicular or oblique manner, with controlled displacement and repetition over elongate regions to minimize thermal impact and improve inspection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a beam of electrons is used to scan the sample surface, then inspection precision is improved, but thermal load on the sample increases causing distortion
Solution Approach 1:
The patent applies periodic action by scanning the electron beam in a structured pattern that systematically moves across different regions of the sample surface over time. The beam is repeatedly directed to different locations in a controlled sequence, allowing thermal diffusion between scans and preventing continuous concentration of thermal energy on a single spot, thereby reducing overall thermal load while maintaining inspection precision
Solution Approach 2:
The patent introduces a temporal dimension to the scanning process by implementing repeated scanning cycles with systematic displacement between scans. Instead of a single continuous scan, the method performs multiple scans with the beam returning to previously scanned areas after time intervals, allowing thermal effects to dissipate and reducing cumulative thermal damage while maintaining measurement precision
2Measurement precision
If the electron beam is focused on a small probing spot, then measurement precision is improved, but thermal concentration on that spot increases
Solution Approach 1:
The patent implements periodic scanning where the focused electron beam repeatedly visits different locations including previously scanned areas. By spacing scans in time and systematically moving the beam across the sample surface, the method allows thermal energy to dissipate from concentrated spots between scans, reducing peak temperatures while maintaining the precision benefits of beam focusing
Solution Approach 2:
The patent applies dynamics by making the scanning process adaptive and systematic rather than static. The beam scanning pattern dynamically adjusts to revisit previously scanned regions after displacement, creating a time-varying scan pattern that distributes thermal load over time and space while maintaining focused beam precision for measurement
3Productivity
If the sample is moved continuously during scanning, then throughput is improved, but position accuracy decreases due to thermal distortion
Solution Approach 1:
The patent implements periodic scanning with systematic displacement, where the sample or beam is moved in controlled increments between scanning cycles. This periodic movement pattern allows for systematic coverage of the sample surface while providing time intervals for thermal stabilization, thereby maintaining position accuracy across different scanned regions without sacrificing overall throughput
Solution Approach 2:
The patent adds a temporal dimension to the scanning process by performing repeated scans with systematic displacement between cycles. This multi-pass approach with time intervals allows thermal distortion to be managed between scans while maintaining continuous productivity through systematic coverage of the entire sample surface over multiple scanning cycles
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 enhances throughput and maintains position accuracy by reducing thermal stress on samples, thereby improving the yield and efficiency of defect detection in semiconductor manufacturing.
Implementation Method 1
The interactions between the material structure at the probing spot and the landing electrons from the beam of electrons cause signal electrons to be emitted from the surface, such as secondary electrons
Implementation Method 2
Exposing a sample to a beam of electrons can apply a thermal load to the sample. Such a thermal load may cause distortion in the sample resulting in position errors
Data Source
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AI summary
Methods of processing a sample and charged particle assessment systems are disclosed. In one arrangement, a sample is processed using a multi-beam of sub-beams of charged particles. At least a portion of a sub-beam processable area is processed with each sub-beam. The sub-beam processable area comprising an array of sections having rows of sections and columns of sections. Each row of sections defines an elongate region that is substantially equal to or smaller than a pitch at the sample surface of the sub-beams in the multi-beam. A plurality of the sections are processed.