Buried Defect Depth Estimation Using Energy-Resolved BSE Scans
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Solution Overview
Problem
Current methods for examining defects in semiconductor specimens, particularly those buried within multiple layers, face challenges in accurately determining the depth of defects without destructive measures and often require multiple scans using different landing energies, leading to low throughput and unreliable results.
Innovation Solution
A computerized system that uses an electron beam with a given landing energy to scan a semiconductor specimen and collect backscattered electrons at a specific escape energy, selected based on a relationship derived for different expected depths, allowing for a single scan to estimate the actual depth of the defect with improved accuracy and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple scans with different landing energies are used to determine defect depth, then measurement precision is improved, but productivity deteriorates due to low throughput
Solution Approach 1:
The system pre-calculates and stores a database of simulated BSE signals for defects at various depths and compositions before actual examination. During scanning, the measured signal is directly compared against this pre-prepared database to rapidly determine defect depth and composition, eliminating the need for multiple iterative scans with different landing energies while maintaining high measurement precision
Solution Approach 2:
The system utilizes the energy spectrum distribution of backscattered electrons as an additional measurement parameter. By analyzing the BSE signal at a fixed landing energy across different energy channels, the system can simultaneously determine both defect depth and composition from a single scan, rather than requiring multiple scans at different landing energies
2Reliability
If multiple scans with different landing energies are performed to accurately determine defect depth, then reliability is improved, but loss of time increases
Solution Approach 1:
The system performs comprehensive simulations and pre-calculates BSE signals for various defect depths, compositions, and landing energies before actual examination. This pre-computed database enables rapid and reliable defect characterization during scanning by direct comparison, eliminating the need for time-consuming multiple scans while ensuring accurate depth determination
Solution Approach 2:
The system achieves multi-functionality by using a single scanning configuration (fixed landing energy) to simultaneously extract multiple parameters including defect depth, composition, and size from the energy-resolved BSE signal spectrum, rather than requiring separate scans for each parameter
3Productivity
If a single scan is used to improve throughput, then productivity is improved, but measurement precision deteriorates for buried defect depth determination
Solution Approach 1:
The system adds the energy dimension to the BSE signal analysis by resolving the signal into an energy spectrum distribution. This additional dimensional information allows the system to distinguish between signals from different depths and compositions within a single scan, maintaining high measurement precision for buried defects while achieving improved throughput
Solution Approach 2:
The system pre-calculates comprehensive databases of BSE signals for defects at various depths, compositions, and sizes before examination. During single-scan operation, the measured energy-resolved signal is compared against this pre-prepared database to accurately determine defect parameters without requiring multiple scans
4Device complexity
If conventional examination methods are used without energy-resolved detection, then device complexity is reduced, but measurement precision deteriorates for buried defect analysis
Solution Approach 1:
The system introduces energy-resolved detection by adding energy discrimination capability to the BSE detection system. This allows the examination tool to measure not only the intensity but also the energy distribution of backscattered electrons, providing additional information about defect depth and composition without significantly increasing overall system complexity
Solution Approach 2:
The system uses an energy filter or energy-resolved detector as an intermediary between the specimen and the detection system. This intermediary component separates and measures BSEs at different energy levels, enabling precise depth determination of buried defects while maintaining relatively simple system architecture
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 enables accurate depth estimation of defects in semiconductor specimens with improved throughput by selecting an optimal escape energy for defect depth determination, reducing the need for multiple scans and enhancing the reliability of defect depth analysis.
Implementation Method 1
an examination tool configured to scan the semiconductor specimen using an electron beam with a given landing energy (LE), and generate image data by collecting backscattered electrons (BSEs) emitted from the specimen
Data Source
AI summary
There is provided a system and method of examining a defect buried in a semiconductor specimen. The method comprises: scanning the semiconductor specimen using an electron beam with a given landing energy (LE); generating image data by collecting backscattered electrons (BSEs) emitted from the specimen at a specific escape energy (EE), wherein the specific EE is selected from a series of EEs corresponding to the given LE based on a relationship representative of expected measurements obtained at the series of EEs for different expected depths of the defect in the specimen; obtaining a measurement related to the defect based on the image data; and estimating an actual depth of the defect in the specimen based on the measurement and the relationship.