Static Secondary Mass Spectrometry Range of elements H to U: all isotopes Destructive Yes. if sputtered long enough ° Chemical bonding Y ° Depth probed Outer I or 2 monolayers Lateral resolution Down below 100 nm Imaging/mapping Yes Quantification Possible with suitable standards Mass range Typically up to 1000 amu: 10,000 amu( TOF) e Sample requirements Solid, liquids, powder; must be vacuum compatible Main use Surface chemical analysis, organics, polymers Instrument cost USS500,000-750,000
Mass Spectrum si 05 100 150 200 Mass-to-charge ratio Aluminum ore
Dynamic Secondary Ion Mass spectrometry Dynamic SIMS involves the use of a much higher energy primary beam(larger amp beam current). It is used to generate sample depth profiles. The higher ion flux eats away at the surface of the sample, burying the beam steadily deeper into the sample and generating secondary ions that characterize the composition at varying depths The beam typically consists of t or Cst ions and has a diameter of less than 10 um. The experiment time is typically less than a second. lon yield changes with time as primary particles build up on the material effecting the ejection and path of secondary ions Range of element H to U: all isotopes Destructive Yes, material removed during sputtering Chemical bonding In rare cases. from molecular cluster: see StatiC SIMS Quantification Standard usually needed Accuracy 2% Detection limits 1012-1016 atoms/cm(ppb-ppm Depth probed Yes; sputtering; resolution 2-30 nI Imaging/mapping Yes ° Sample requirements Solid;dia≤2.5cm/ thick≤6mm;vac. compatible Cost USS500,000-1,500,000
Dynamic SIMS involves the use of a much higher energy primary beam (larger amp beam current). It is used to generate sample depth profiles. The higher ion flux eats away at the surface of the sample, burying the beam steadily deeper into the sample and generating secondary ions that characterize the composition at varying depths. The beam typically consists of O2 + or Cs+ ions and has a diameter of less than 10 μm. The experiment time is typically less than a second. Ion yield changes with time as primary particles build up on the material effecting the ejection and path of secondary ions. Dynamic Secondary Ion Mass Spectrometry
Dynamic sims- Depth profiling I+ B+c B B C C B Time Factors affecting Crater edge rejection Raster beam for flat bottomed crater depth resolution Accept ions only from center of crater I lon beam mixing Primary ion mass Impact energy Impact angle Surface roughening http:/www.youtube.com/watch?v=7gsbasircu&feature=relatedmetalsworsethansinglecrystalmateria
Dynamic SIMS – Depth Profiling Factors affecting depth resolution http://www.youtube.com/watch?v=-7gSbaslRCU&feature=related
CRATER EFFECT The shape of the depth profile a B can be affected by a) Redeposition by sputtering from the crater wall onto the analysis area B b) Direct sputtering from the crater wall Depth