TOF Time of Flight SIMS System Specifications
Ion Gun
The ion gun generates a focused ion beam used to sputter material from the sample.
- Beam energy of 5 keV
- Operates on inert gases (Ar, Kr, or Xe)
- Gases ionized with dual-filament electron impact source
- Blanking plates
- x, ydeflection and rastering
- Adjustable condenser lens settings for variable beam current
- High-speed pulser (5-200 ns width with ~2 ns rise and fall time) used to control blanking of ion beam
Pumping System
The pumping system (pumps and gauges) for the analysis chamber and ion gun are controlled and monitored by the computer.
- 500 l/s turbomolecular pump (TMP) on chamber and 60 l/s TMP on ion gun
- Turbo pumps backed by a 160 l/min roughing pump
- 60 l/s TMP on sample lock backed by 30 l/min roughing pump
- Controller for load-lock TMP conveniently located on rack panel
- >Dual-filament computer controlled ion gauges
Sample Loading
A four-compartment system allows high sample throughput.
- 1” x 2” sample holders transferred from parking tray to main transfer arm by magnetic transporter
- Samples transferred into analysis chamber by magnetic transporter
- Pneumatic valve separates analysis and load-lock chambers
Sample Manipulator
A computer controlled x, y, z manipulator is used for general sample manipulation and imaging.
- 25 mm travel in y and z, and 50 mm travel in x
- 5 mm step resolution
- Images collected by rastering ion beam, rastering sample, or combination of both
Time-Of-Flight Mass Spectrometer
The ion optics are designed to maximize throughput for a variety of sample configurations.
- Positive and negative ion modes
- Large extraction gap allows analysis of samples with different thicknesses
- Post acceleration improves mass resolution by greater than 4x
- x, y steering and lens
- Mass resolution (m/Dm) >800 at 41 amu and >2200 at 430 amu
- Linear Time-of-Flight analyzer allows parallel detection of all masses
- Optional reflectron analyzer available for higher mass resolution.
Data Acquisition and Imaging
A dual channel plate assembly and high-speed time-to-digital converter (TDC) are used for data acquisition.
- Multi-stop TDC
- Variable time resolution (time per TDC bin in multiples of 278 ps)
- Data inhibit mode with variable start time and time range
Computer Interface
The majority of systems on the SIMS instrument are controlled and monitored by a computer integrated LabView system.
- Monitors pirani gauge for roughing system and ion gauges for chamber and ion gun
- Pop-up controls for pumping system and gauges, manipulator, pulse timing, gun rastering, and spectrometer voltages
- Data acquisition program collects positive and negative ion spectra, converts time to mass spectrum with user-friendly calibration routine, and collects images by rastering ion gun, moving manipulator, or combination of the two
Charge Compensation (Optional)
Charge build-up on insulating samples is efficiently removed by flooding the sample with electrons between extraction cycles.
- Independently adjustable beam energy, beam current, and spot size
- Beam energy variable between 50 eV to 1500 eV
- Beam current range of 1 nA to 100 mA
- x, y deflection
The SIMS instrument is equipped with an optical microscope and camera for sample viewing.
- Optical microscope with x25 magnification
- Color CCD video camera allows live display on PC monitor
- Video frame grabber to capture and store images
