Calibration Component for Electron-Beam Scale-Factor Accuracy
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Solution Overview
Problem
Conventional superlattice samples used for scale-factor calibration in electron-beam systems face challenges such as contamination adhesion and pattern deformation due to high beam dosage, leading to reduced calibration accuracy, and difficulty in identifying the calibration position within the beam-unirradiated area.
Innovation Solution
A standard component with a superlattice pattern and calibration position identification marks formed using heavy metals like aluminum, tungsten, or molybdenum, arranged at fixed intervals on the substrate surface, allowing for precise positioning and high-contrast secondary electron imaging, enabling accurate calibration regardless of stage and beam deflection inaccuracies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a superlattice sample is used for scale-factor calibration with high magnification (100,000 or more), then measurement precision is improved, but contamination adhesion increases and pattern deformation occurs due to accumulated beam dosage
Solution Approach 1:
The calibration sample is divided into multiple independent calibration areas (first calibration area, second calibration area, etc.) arranged in different regions. This segmentation allows the electron beam to irradiate different calibration areas sequentially, preventing accumulated beam dosage in a single area and thereby reducing contamination adhesion and pattern deformation while maintaining measurement precision.
Solution Approach 2:
After a calibration area has been irradiated and contaminated, the system automatically switches to a different calibration area for subsequent measurements. The previously irradiated area is effectively discarded and not used again, while a fresh calibration area is activated. This approach recovers the calibration function by continuously providing uncontaminated calibration regions.
2Device complexity
If a continuous line pattern is used in the superlattice sample, then the sample structure is simple, but position identification becomes difficult in the beam-unirradiated area
Solution Approach 1:
Within the calibration marks, specific local structures are introduced: first calibration marks include first line patterns extending in a first direction, while second calibration marks include second line patterns extending in a second direction different from the first. These directional differences create distinct local qualities that enable easy position identification and orientation recognition without significantly increasing overall sample complexity.
Solution Approach 2:
The calibration marks are designed with asymmetric characteristics through the use of line patterns in different directions. The first calibration marks have line patterns oriented in one direction, while second calibration marks have line patterns oriented in another direction, creating asymmetric features that facilitate unambiguous position and orientation identification.
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 enables high-accuracy scale-factor calibration by facilitating easy identification of the calibration position and reducing pattern deformation, maintaining calibration accuracy even with repeated use, and allowing for precise linewidth measurement.
Implementation Method 1
a formed mark is required to be one that gives sufficient contrast on a secondary charged particle (secondary electron, reflected electron, etc.) image by electron beam irradiation
Implementation Method 2
by the mark using a metal material, such as aluminum (Al), tungsten (W), tantalum (Ta), molybdenum (Mo), and copper (Cu), especially a heavy metal, the mark is free from electrification and can obtain a secondary electron signal whose contrast is high to the superlattice substrate
Data Source
AI summary
The invention provides a standard component for calibration that enables a calibration position to be easily specified in order to calibrate accurately a scale factor in the electron-beam system, and provides an electron-beam system using it. The standard component for calibration is one that calibrates a scale factor of an electron-beam system based on a signal of secondary charged particles detected by irradiation of a primary electron beam on a substrate having a cross section of a superlattice of a multi-layer structure in which different materials are deposited alternately. The substrate has linear patterns on the substrate surface parallel to the multi-layers and are arranged at a fixed interval in a direction crossing the cross section of the superlattice pattern, and the cross sections of the linear patterns are on substantially the same plane of the superlattice cross section, so that the linear patterns enable a position of the superlattice pattern to be identified.