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FEI Strata 235DB DualBeam FIB/SEM


The instrument is an FEI Strata 235DB dual-beam FIB/SEM, containing both a focused Ga+ ion beam column ("Magnum") and a high resolution field emission scanning electron ("Sirion") column. The utility of the columns is enhanced by the ability to selectively deposit Pt or insulator with either of the two beams and rapidly etch many insulating materials using XeF2. Further, there is an Omniprobe® micromanipulator within the chamber that can position devices with nanoscale precision as well as measure electrical properties. The instrument is located on the first floor of McCullough Building, Room 105.


  • Imaging: Secondary electrons or ions produced by the incoming electron or Ga+ beams are collected to form an image of the sample. Five different detectors (including a STEM detector) give users tremendous flexibility in achieving the proper imaging conditions for their sample.
    • Ion column
      • Accelerating voltage: 10 – 30 kV
      • Resolution: 7 nm
    • Electron column
      • Accelerating voltage: 0.5 – 30 kV
      • Resolution: 3 nm
  • Milling/Etching: The FIB can locally etch the sample surface with submicron precision. Many variables and material properties affect the sputtering rate of a sample. These include beam current, sample density, sample atomic mass, and incoming ion mass. The ion species used at SNSF is Ga+. Additionally, Insulator Enhanced Etching (IEE) using XeF2 gas is available. Additionally, Insulator Enhanced Etching (IEE) using XeF2 is available. When the gas is introduced near the surface of the sample during milling, the sputtering yield can increase depending on the chemistry between the gas and the sample. This results in less redeposition and more efficient milling.
  • Deposition: Conductive or insulator material can also be deposited with the aid of a gas in close proximity to the sample surface. Our system is equipped to deposit either metal (Pt) or insulator (combined tetraethyl orthosilicate (TEOS) and water vapor). These materials can be deposited with either the ion or electron beam.
  • Micromachining: The FIB can be utilized for micro- and nano-structural creation and/or modification. This can be accomplished by taking advantage of FIB's capability to very precisely remove material (via physical sputtering or using beam induced chemistry for enhancing material removal rate), to deposit material (using beam induced chemistry), to provide localized ion implantation, and to locally induce sample structural damage.
  • Microchemical analysis: Element mapping and energy dispersive X-ray spectrometry (EDS) are available.
  • Nanoscale manipulation: The system is capable of nanoscale manipulation of TEM membranes or other samples with an Omniprobe micromanipulator. This probe can also be used for localized electronic measurements.

Restrictions on samples
The sample material must be able to withstand a high vacuum environment without outgassing. It must be clean.It may be attached to the sample holder using SEM vacuum-quality C or Ag paint or clips. The sample must be electrically grounded to the sample holder to minimize sample charging. If the sample is nonconductive (plastic, fiber, polymer, or other substance with an electrical resistance greater than 1E10 ohms), the sample may be coated with a 200 – 300 Å layer of carbon or other conductor. Rough surfaced samples must be evenly coated from every direction. Biological, cloth and powder samples may require carbon or other conductive painting on portions of the sample that are hard to coat. The workstation can accommodate up to 150 mm (6") wafers.

For Au/Pd (60:40 ratio) coating on your samples, please do the following:

  • Bring your mounted sample(s) in a case (labeled with your contact info, any non-standard parameters, and the time of your scheduled microscope session) to the Sample Mounting Lab in McCullough 101.  The overhead cabinet to the right of the coater is labeled with one side where you will drop off your sample (“Samples to be coated”), and the other for where we will place the coated samples.
  • Email “” to let us know that you have dropped off your sample(s) - similarly indicate when your microscope session will be.  Please remember that we may not be able to get to it immediately, so last-second requests will be difficult.
  • When we are finished coating, we will put it back in the “Coated samples” side of the cabinet and you can pick it up.

Contact Information

Richard Chin
office: (650) 723-8142

Juliet Jamtgaard
office: (650) 736-1256

Ann Marshall
office: (650) 723-3572

McCullough Room 105
Phone: (650) 725-6921


Getting Started

In order to become a qualified user on the DB235, you need to follow these steps :

Training Information

It is recommended to have three training sessions (generally, 2 standard plus 1 final) to become authorized on the DB235.  Training sessions occur at routine times and dates on the calendar.  Please contact a trainer if you cannot make existing training sessions. 

To sign up for training on the DB235, please read and follow these instructions:

  • DB235 Sign-up calendar:
  • To edit fields on the calendar, you must log in (found on the right hand side).
    Username: DB235
    Password: fibD1000
    • Look for training slots on the sign-up calendar marked "training w/(trainer)" (note: "reserved for trainers" does not equal "training w/ (trainer)"; early entries into such slots will be deleted).
    • Click on the pencil icon to add your name (to the subject line) and contact info (further down the page). The final entries should look like:
      • "training w/ rich/ jane/ joe" for a regular training, and
      • "training w/ rich/ pat (final)" for a final training.
    • New training slots are posted Monday mornings. No more than two people per session, please, and only one person if it is a final. Furthermore, please do not sign up for successive trainings on the same day; from past experience, the information is not absorbed as well, and all too often people have to re-take their final.
    • For the first several sessions following the successful completion of a "final" training, you will be allowed to sign up by yourself, but only during business hours. Further details will be explained when you receive your Beginner's Permit. Full (24hrs/7days) access will be granted after successful completion of the permit.
    • Note: you will be charged for no-shows if you do not let us know at least 12 hours in advance of your scheduled time.

After you are qualified on the DB235, you may sign up for technique sessions, such as Omniprobe Training or EDS Training. These advanced sessions are offered about once per month or on an as-needed basis, and up to 6 people may sign up for each one. They are designed to provide a basic introduction to the technique, and further training may be required by the instructor. Note: you will be charged for no-shows if you do not let us know of a cancellation at least 24 hours in advance of your scheduled time.

Other information