SIMS Metrology with Low Extraction Field and Charge Compensation
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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.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional SIMS systems are used for surface analysis, then measurement sensitivity is achieved, but measurement time is excessive and cost is high
Solution Approach 1:
The patent segments the measurement process by implementing multiple detectors that operate in parallel to measure different species simultaneously. This allows the system to divide the total measurement task across multiple detection channels, significantly reducing the time required to achieve comprehensive compositional analysis while maintaining high sensitivity through the specialized detection capabilities of each detector type
Solution Approach 2:
The patent implements periodic action through pulsed ion beam operation and time-of-flight mass analysis. By using short, intense ion pulses and measuring ion arrival times, the system achieves rapid sequential measurement of different mass-to-charge ratios, enabling fast dynamic SIMS measurements that maintain high sensitivity while reducing total measurement time compared to continuous scanning methods
2Measurement precision
If conventional SIMS systems are used for surface analysis, then measurement sensitivity is achieved, but system cost and maintenance complexity increase
Solution Approach 1:
The patent merges multiple detection functions into a unified time-of-flight mass spectrometer system with parallel detector array. By combining static SIMS and dynamic SIMS capabilities in a single instrument with integrated charge compensation and multiple detector types, the system achieves high sensitivity measurement while reducing operational complexity and cost compared to requiring multiple separate specialized instruments
Solution Approach 2:
The patent implements universality by designing a multi-functional SIMS system that can perform both static surface analysis and dynamic depth profiling measurements using the same primary ion beam and mass spectrometer. The system can analyze a wide range of materials and compositional ranges through configurable detector selection and measurement mode switching, reducing the need for multiple specialized systems and associated maintenance costs
3Productivity
If high extraction voltage is used in SIMS, then ion collection efficiency is improved, but sample charging and depth resolution deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the extraction voltage to a specific range (1-10 eV) that balances ion collection efficiency with depth resolution preservation. This parameter optimization, combined with low-energy primary ion beam selection (5-50 keV), achieves sufficient ion yield for sensitive detection while maintaining the shallow penetration and sharp depth profiles needed for high-resolution surface and interface analysis
4Measurement precision
If conventional SIMS measurement approaches are used, then compositional analysis is achieved, but sample charging effects increase
Solution Approach 1:
The patent introduces charge compensation as an intermediary mechanism that counteracts sample charging effects. By implementing electron or ion flood guns that deposit opposite charge during measurement, the system maintains electrical neutrality of the sample surface, preventing charging-induced beam deflection and energy shifts that would compromise compositional accuracy, while allowing high-sensitivity SIMS analysis of insulating and semi-conducting materials
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 enables faster, more accurate measurements with improved depth resolution and reduced sample charging, making it suitable for inline process control in semiconductor manufacturing.
Implementation Method 1
SIMS is a technique used to analyze the composition of solid surfaces and thin films 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).