SIMS Metrology With Low Extraction Field for Depth Resolution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current Secondary Ion Mass Spectrometry (SIMS) systems face challenges in inline semiconductor manufacturing due to high costs, time-consuming measurements, and maintenance issues, as well as difficulties with sample charging and depth resolution, which hinder their use in process control.
Innovation Solution
A SIMS system with a low extraction voltage and a magnetic sector spectrograph configuration, including multiple detectors for parallel species measurement, and a charge compensation system using electrostatic analyzers and electron flood neutralization, addresses the challenges of measurement speed, accuracy, and sample charging, enabling more efficient and precise analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional SIMS systems use high extraction fields for secondary ion collection, then ion signal intensity is improved, but depth resolution deteriorates due to ion energy spreading
Solution Approach 1:
The patent changes the extraction field parameter from conventional high values to low values (e.g., extraction voltage of 1-10 V compared to conventional 100-1000 V), which reduces ion energy spreading and improves depth resolution while maintaining adequate signal intensity through optimized detector sensitivity and ion optics
Solution Approach 2:
The system dynamically adjusts extraction field strength based on measurement requirements, using low extraction fields for depth profiling applications requiring high resolution, and can switch to higher fields when signal intensity is the priority, optimizing performance for different operational modes
2Measurement precision
If SIMS measurements are performed on insulating semiconductor materials, then compositional analysis capability is improved, but sample charging occurs causing measurement instability
Solution Approach 1:
The patent introduces a charge compensation system using electron flood guns or low-energy ion beams as intermediary charge carriers to neutralize accumulated charge on insulating sample surfaces, enabling stable compositional analysis without compromising measurement accuracy
Solution Approach 2:
The system applies charge compensation locally to specific regions of the sample surface being analyzed, using focused electron or ion beams to neutralize charge only in the immediate analysis area, maintaining compositional analysis accuracy while preventing global sample charging effects
3Productivity
If conventional SIMS systems use sequential single-detector measurement, then system complexity is reduced, but measurement time increases
Solution Approach 1:
The patent segments the detection function across multiple detectors (e.g., quadrupole mass spectrometer with multiple detection channels, or array of time-of-flight detectors), allowing parallel measurement of different mass-to-charge ratios simultaneously, thereby increasing measurement speed while managing complexity through modular detector architecture
Solution Approach 2:
The system employs universal detector platforms such as quadrupole mass filters or time-of-flight analyzers that can detect multiple ion species across a broad mass range through a single instrument, achieving high-speed multi-element analysis without proportionally increasing system complexity
4Measurement precision
If SIMS systems operate in high vacuum environment, then secondary ion mean free path is extended improving detection, but system complexity and maintenance requirements increase
Solution Approach 1:
The patent implements periodic pumping cycles or pulsed vacuum maintenance where the vacuum system operates at full capacity only during critical measurement phases, and uses getter materials or cryopumping surfaces to maintain acceptable vacuum levels between active pumping periods, reducing overall system complexity while preserving detection sensitivity
Solution Approach 2:
The system incorporates disposable or replaceable vacuum maintenance components such as non-evaporable getter (NEG) pumps, cryopumping surfaces, or sacrificial vacuum barriers that can be easily replaced rather than requiring complex, permanently maintained high-vacuum systems, reducing long-term operational complexity
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 system achieves faster and more accurate measurements with improved depth resolution and reduced sample charging, enhancing its suitability for inline process control in semiconductor manufacturing by maintaining measurement consistency and reducing maintenance needs.
Implementation Method 1
by sputtering the surface of the specimen with a focused primary ion beam and collecting and analyzing ejected secondary ions
Implementation Method 2
An extraction lens is directed at the sample stage. The extraction lens is configured to provide a low extraction field for secondary ions emitted from a sample on the sample stage
Implementation Method 3
A magnetic sector spectrograph is coupled to the extraction lens along an optical path of the SIMS system. The magnetic sector spectrograph includes an electrostatic analyzer (ESA) coupled to a magnetic sector analyzer (MSA)
Implementation Method 4
The magnetic sector spectrograph includes an electrostatic analyzer (ESA) coupled to a magnetic sector analyzer (MSA)
Implementation Method 5
a charge compensation system using electrostatic analyzers and electron flood neutralization
Data Source
AI summary
Systems and approaches for semiconductor metrology and surface analysis using Secondary Ion Mass Spectrometry (SIMS) are disclosed. In an example, a secondary ion mass spectrometry (SIMS) system includes a sample stage. A primary ion beam is directed to the sample stage. An extraction lens is directed at the sample stage. The extraction lens is configured to provide a low extraction field for secondary ions emitted from a sample on the sample stage. A magnetic sector spectrograph is coupled to the extraction lens along an optical path of the SIMS system. The magnetic sector spectrograph includes an electrostatic analyzer (ESA) coupled to a magnetic sector analyzer (MSA).