Multi-Electron Beam Deflection Calibration for Accurate Wafer Inspection
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Solution Overview
Problem
Existing multiple electron beam image acquisition methods require additional measurement means to correct for the movement of secondary electron beams, leading to increased apparatus size and cost, as well as potential inaccuracies in defect detection for ultrafine patterns on semiconductor waffers.
Innovation Solution
A method and apparatus that apply a representative primary electron beam to multiple positions within a preset deflection range, perform scanning with secondary electron beams based on temporary deflection conditions, and calculate secondary electron beam deflection conditions to cancel the movement of primary electron beams, allowing for accurate detection by a multi-detector without the need for additional measurement means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional measurement means are used to correct for the movement of secondary electron beams, then the accuracy of defect detection is improved, but the apparatus size and cost increase
Solution Approach 1:
The patent uses the multi-detector itself to acquire images for calculating deflection conditions, rather than requiring separate measurement means. The system performs self-calibration by utilizing its own detection capabilities to determine and correct beam position deviations, thereby avoiding additional hardware while maintaining high measurement precision
Solution Approach 2:
The multi-detector serves dual functions: it both acquires inspection images for defect detection and acquires images for calculating secondary electron beam deflection conditions. This multi-functionality eliminates the need for dedicated measurement devices, reducing apparatus complexity while preserving measurement accuracy
2Productivity
If multiple primary electron beams are scanned across the substrate, then the inspection coverage and productivity are improved, but the position accuracy of secondary electron beams deteriorates due to beam movement
Solution Approach 1:
The patent implements a feedback mechanism where the multi-detector continuously monitors the position of secondary electron beams during scanning. The acquired images are used to calculate actual beam positions, and deflection conditions are adjusted based on these calculations to compensate for position deviations, thereby maintaining measurement precision while enabling multi-beam scanning for improved productivity
Solution Approach 2:
The system performs preliminary acquisition of images at multiple positions to calculate deflection conditions before conducting the actual inspection scanning. This preliminary calibration establishes the necessary correction parameters in advance, allowing the multi-beam scanning to proceed with maintained position accuracy throughout the inspection process
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 solution enables accurate acquisition of secondary electron images by correcting for the movement of secondary electron beams, improving the precision of pattern defect detection on semiconductor wafers and reducing the size and cost of the inspection apparatus.
Implementation Method 1
irradiating an inspection target substrate with multiple electron beams and detecting a secondary electron corresponding to each beam emitted from the inspection target substrate
Implementation Method 2
deflection needs to be performed to swing back (return) a movement of the position of the multiple secondary electron beams
Data Source
AI summary
A multiple electron beam image acquisition method includes performing scanning with a representative secondary electron beam emitted, based on temporary secondary electron beam deflection conditions, for each of plural positions in a primary electron beam deflection range of a representative primary electron beam, acquiring plural coordinates corresponding to the plural positions, based on detected images of the representative secondary electron beam, each detected at any one of the plural positions in the primary electron beam deflection range of the representative primary electron beam, and calculating, using the plural coordinates acquired, secondary electron beam deflection conditions to cancel movement of the representative secondary electron beam due to movement of the representative primary electron beam in the primary electron beam deflection range of the representative primary electron beam and to fix the irradiation position of the representative secondary electron beam to the predetermined detection element.