Si/Mo Calibration Reference for SEM Precision
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Solution Overview
Problem
Conventional calibration references for scanning electron microscopes, such as GaAs super lattices and Si/SiO2, face issues like contamination, astigmatic shifts due to level differences, and reduced precision due to electrification, making high-precision magnification calibration challenging, especially for miniaturized semiconductor devices.
Innovation Solution
A standard reference component with a multiple-layer structure of silicon and molybdenum (Si/Mo) is used, featuring a lamination structure with periodic pitch sizes measured by light- or X-ray diffraction, mounted on a silicon wafer with surface polishing to eliminate level differences and prevent contamination, allowing precise magnification calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GaAs super lattice is used as calibration reference, then micro-precision feature with pitch size of 100 nm or less is achieved, but GaAs compound becomes impurity element contaminating silicon wafer
Solution Approach 1:
The patent changes the material composition parameters by replacing GaAs with Si/Mo multiple-layer structure, maintaining the micro-precision feature while eliminating contamination. The Si/Mo structure provides similar diffraction characteristics for calibration but uses materials that do not contaminate silicon wafers.
Solution Approach 2:
The patent uses a composite multiple-layer structure of Si and Mo films with alternating layers. This composite structure creates the necessary micro-precision diffraction pattern while using materials (Si and Mo) that are compatible with silicon wafer processing and do not introduce contamination.
2Measurement precision
If cross-section sample is used for calibration, then micro-precision feature is achieved, but level difference generates localized surface electric field distribution causing astigmatic shift
Solution Approach 1:
The patent applies surface polishing to eliminate level differences between the calibration reference and substrate surface. By creating an equipotential surface, the localized electric field distribution is eliminated, preventing astigmatic shift while maintaining the micro-precision diffraction features.
Solution Approach 2:
The patent changes the surface topology parameter by polishing the surface to achieve flatness. This parameter change eliminates the level difference that causes electric field concentration, thereby preventing astigmatic shift during electron beam scanning.
3Adaptability or versatility
If Si/SiO2 is used as calibration reference material, then alternative to GaAs is provided, but electrification is generated to electron beam deteriorating calibration precision
Solution Approach 1:
The patent changes the material composition from Si/SiO2 to Si/Mo multiple-layer structure. This parameter change eliminates the electrification problem caused by SiO2 while maintaining material compatibility with silicon wafers. The metallic Mo layers provide good electrical conductivity, preventing charge accumulation.
Solution Approach 2:
The patent uses a composite structure combining Si and Mo materials. This composite approach provides both electrical conductivity (from Mo) to prevent electrification and compatibility with silicon processing, while the multiple-layer structure maintains the necessary diffraction characteristics for calibration.
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 Si/Mo standard reference component achieves calibration precision of 0.5 nm or less, reducing astigmatism and contamination risks, and improves secondary electron signal contrast, enabling reliable and reproducible measurements.
Implementation Method 1
The lamination period of the standard reference component is obtained in advance by light- or X-ray diffraction
Implementation Method 2
The lamination period of the standard reference component is obtained in advance by light- or X-ray diffraction
Implementation Method 3
measures a length of a pattern in an observation area from information on the intensity of secondary electrons or reflected electrons generated by scanning an incident electron beam
Implementation Method 4
generated by scanning an incident electron beam in the observation area on an object to be inspected
Data Source
AI summary
The present invention provides a standard reference component for calibration for performing magnification calibration used in the scanning electron microscope with high precision, and provides a scanning electron microscope technique using it. Provided is a standard reference component for calibration for calibrating a scanning electron microscope that measures a length of a pattern in an observation area from information on the intensity of secondary electrons or reflected electrons generated by scanning an incident electron beam in the observation area on a measuring sample, having: a first substrate on which a multiple-layer is laminated and a second substrate with a recess for holding the first substrate, wherein the first substrate is held in the recess of the second substrate so that a normal direction of the multiple-layer surface may be roughly perpendicular to a normal direction of the second substrate surface, and the multiple-layer has a multiple-layer structure of a film containing silicon and a film containing molybdenum.