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

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

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)

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 خیلی سریع ردش کن. The output, i.e. mass spectrum, is an intensity vs. m/z (mass-to-charge ratio) graph Secondary ion mass spectrometry (SIMS)

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. خیلی سریع ردش کن. Secondary ion mass spectrometry (SIMS)

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)

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)

Secondary ion mass spectrometry (SIMS) How Does SIMS Work? Typical schematic of a SIMS instrument. خیلی سریع ردش کن. Secondary ion mass spectrometry (SIMS)

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

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. خیلی سریع ردش کن. Secondary ion mass spectrometry (SIMS)

Static and dynamic modes خیلی سریع ردش کن. Secondary ion mass spectrometry (SIMS)

Secondary ion mass spectrometry (SIMS) Sputtering Effects خیلی سریع ردش کن. Secondary ion mass spectrometry (SIMS)

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 خیلی سریع ردش کن. Secondary ion mass spectrometry (SIMS)

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

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

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

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 خیلی سریع ردش کن. Secondary ion mass spectrometry (SIMS)

Secondary ion mass spectrometry (SIMS) A Typical SIMS خیلی سریع ردش کن. Secondary ion mass spectrometry (SIMS)

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, 2007. http://www.bioacademy.gr [3] P. K. Chu. “Secondary Ion Mass Spectrometry,” University of Hong Kong [4] http://www.chm.bris.ac.uk [5] http://serc.carleton.edu [6] http://en.wikipedia.org [7] http://www.eaglabs.com [8] http://researcher.watson.ibm.com خیلی سریع ردش کن. Secondary ion mass spectrometry (SIMS)

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