2. Secondary ion mass spectrometry (SIMS)
By:
Mohsen Mahmoudi
Supervisor:
Dr. Kolahdoz
School of Electrical and Computer Engineering
College of Engineering
University of Tehran
Fall 91

3. Secondary ion mass spectrometry (SIMS)
Outline
Introduction to MassSpectrometer
Introduction & Application of SIMS
How does SIMS work?
Limitations of SIMS
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Secondary ion mass spectrometry (SIMS)

4. Mass Spectrometer (MS)
MS Application
Determining masses of particles
Determining the elemental composition of a sample or molecule
Elucidating the chemical structures of molecules, such as peptides and other chemical compounds
Is a kind of machine which uses an analytical technique to measure the mass-to-charge ratio of charged particles(ions)
This analytical technique is also known as Mass Spectrometry.
MS works by ionizing chemical compounds to generate charged molecules or molecule fragments and measuring their mass-to-charge ratios
خیلی سریع ردش کن.
Secondary ion mass spectrometry (SIMS)

5. General Structure of Mass Spectrometer
Generally, a typical Mass Spectrometer consists of three parts: an ion source, a mass analyzer and a detector
The function of the ion source is to produce ions from the sample.
The function of the Mass Analyzer is to separate ions with different mass-to-charge ratios
Then the numbers of different ions are detected by the detector
Finally, the mass spectrum is generated after all the data have been collected
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The output, i.e. mass spectrum, is an intensity vs. m/z (mass-to-charge ratio) graph
Secondary ion mass spectrometry (SIMS)

6. Types of Mass Spectrometers
For example:
ICP-MS (Inductively coupled plasma-mass spectrometry)
AMS (Accelerator mass spectrometry)
TIMS (Thermal ionization-mass spectrometry)
SSMS (Spark source mass spectrometry)
IRMS (Isotope ratio mass spectrometry)
SIMS( Secondary ion mass spectrometry)
Due to the differences in ionization techniques, various analyzers and detectors, the mass spectrometers can be divided into several types.
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Secondary ion mass spectrometry (SIMS)

7. Secondary ion mass spectrometry (SIMS)
Introduction to SIMS
SIMS is based on the observation that charged particles (Secondary Ions) are ejected from a sample surface when bombarded by a primary beam of heavy particles.
خیلی سریع ردش کن.
Secondary ion mass spectrometry (SIMS)

8. Secondary ion mass spectrometry (SIMS)
Structure of SIMS
Typically, a secondary ion mass spectrometer consists of:
Primary ion gun generating the primary ion beam primary ion column, accelerating and focusing the beam onto the sample
High vacuum sample chamber holding the sample and the secondary ion extraction lens
Mass analyzer separating the ions according to their mass- to- charge ratio
Ion detection unit.
خیلی سریع ردش کن.
Secondary ion mass spectrometry (SIMS)

9. Secondary ion mass spectrometry (SIMS)
How Does SIMS Work?
Typical schematic of a SIMS instrument.
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Secondary ion mass spectrometry (SIMS)

10. Secondary ion mass spectrometry (SIMS)
Step 1, 2
High energy ions are supplied by an ion gun
SIMS Primary Ion Sources:
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Secondary ion mass spectrometry (SIMS)

11. Secondary ion mass spectrometry (SIMS)
Step 3, 4
Accelerating and focusing the beam onto the target sample
Which ionizes and sputters some atoms off the surface
This leads to the ejection (or sputtering) of both neutral and charged (+/-) species from the surface.
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Secondary ion mass spectrometry (SIMS)

12. Static and dynamic modes
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Secondary ion mass spectrometry (SIMS)

13. Secondary ion mass spectrometry (SIMS)
Sputtering Effects
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Secondary ion mass spectrometry (SIMS)

14. Secondary ion mass spectrometry (SIMS)
Step 5, 6
These secondary ions are then collected by ion lenses
Ions generated by this process form the secondary beam and are subsequently transmitted within a continuous high vacuum environment to a mass spectrometer
Filtered according to atomic mass
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Secondary ion mass spectrometry (SIMS)

15. Secondary ion mass spectrometry (SIMS)
Mass analyzers
Depending on the SIMS type, there are three basic analyzers available:
time-of-flight
sector
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Quadrupole
Secondary ion mass spectrometry (SIMS)

16. Secondary ion mass spectrometry (SIMS)
Step 7
Then projected onto an electron multiplier (top), Faraday cup ( bottom)
Ion detectors
Electron multiplier
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Faraday cup
Secondary ion mass spectrometry (SIMS)

17. Secondary ion mass spectrometry (SIMS)
Step 8
3D Image
Depth of profiling
CCD screen
Mass spectrum diagram
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Secondary ion mass spectrometry (SIMS)

18. Secondary ion mass spectrometry (SIMS)
Limitations
Generally does not produce quantitative analyses
Optical capabilities are typically limited
Charging may be a problem in some samples
There is commonly an image shift when changing from positive to negative ion data collection mode;
Too much data
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Secondary ion mass spectrometry (SIMS)

19. Secondary ion mass spectrometry (SIMS)
A Typical SIMS
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Secondary ion mass spectrometry (SIMS)

20. Secondary ion mass spectrometry (SIMS)
References
[1] J. D. Plummer, M. D. Deal, and P. B. Griffin.“Silicon VLSI Technology: Fundamentals, Practice, and Modeling,” Prentice Hall, 2000 [2] L, Cheng. “Introduction to Mass Spectrometer,” Helsinki, [3] P. K. Chu. “Secondary Ion Mass Spectrometry,” University of Hong Kong [4] [5] [6] [7] [8]
خیلی سریع ردش کن.
Secondary ion mass spectrometry (SIMS)

21. Thanks for Your Attention.
University of Tehran
School of Electrical and Computer Engineering
Fall 91