Woollam M-2000 Ellipsometer

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Woollam M-2000 Ellipsometer
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Equipment Details
Technology Metrology
Materials Restriction Metals
Sample Size pieces up to 6" wafers
Equipment Manual
Overview System overview
Operating Procedure SOP
Supported Processes Supported Processes
Maintenance Maintenance


The Woollam M-2000 is a spectroscopic ellipsometer capable of extracting thickness and index of refraction for transparent and semi-transparent thin films or coatings. It is equipped with fully automated sample alignment with stage tip/tilt and focus. It has a high speed CCD detector for collection of data across the full spectral range of 193-1683 nm simultaneously. Typical acquisition time is 5 sec per site per angle.

Announcements

None at this time.

Capabilities

  • Thickness range: From 10 Å to several μm (Note: Maximum thickness is film dependent.)
  • For very thin films (less than ~150 Å), ellipsometry loses sensitivity to optical constants. To measure the thickness of these films, the model for n and k must be assumed or determined from a thicker sample (assuming the optical constants are the same for both thick and thin samples).
  • Since only two values are being measured at each wavelength, only two unknowns can independently be solved at each wavelength (thickness and n, n and k, thickness1 and thickness2, etc). This must be kept in mind when building and fitting a model to the data set. If too many unknowns are included in the model, the fitting result may not be valid or unique.
  • For absorbing films, the film must be thin enough so it is not opaque. Metals thicker than ~1000 Å are typically opaque for reflection measurements.
  • In addition to standard ellipsometry measurements, this tool can be used for:
    • Transmission intensity measurements for samples with transparent substrates
    • Angled reflection intensity measurements
    • Contact the tool owner by submitting a Helpdesk Ticket for support of these measurements.

System overview

Hardware details

  • Wavelength range: 193-1683 nm
  • Variable angle range: 45 to 90 degrees
  • Spot size: (3 mm diameter)
    • Without focusing optics is 3 mm x 12 mm @ 75 degree angle of incidence
    • With focusing optics is 300 μm x 1.2 mm @ 75 degree angle of incidence.
      • Note: Focusing optics are available for use with staff assistance.
  • Sample Stage Size: 6” for 150 mm wafers and smaller samples

Substrate requirements

  • Sample must be > 3 mm x 1.2 cm in size to accommodate beam size without focusing optics. (300um x 1.2mm with focusing optics)
  • Substrate types:
    • Material files for various substrates are available including silicon, germanium, GaAs, glass, and others.
    • Single side polished substrates should be used to avoid issues with backside reflections.

Material restrictions

The Woollam M-2000 Ellipsometer is designated as a Metals class tool. Below is a list of approved materials for the tool. Approved means the material is allowed in the tool under normal circumstances. If a material is not listed, please create a helpdesk ticket or email info@lnf.umich.edu for any material requests or questions.


  • No liquids or uncured spin on films.

Supported processes

  • There are automated recipes available on the tool for wafer map characterization of a number of thin film depositions in the LNF.
  • If there is a common use recipe you would like to have added to the tool, please submit a Helpdesk Ticket to contact the tool owner.


Standard operating procedure

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Checkout procedure

  1. Read through this page and the Standard Operating Procedure above.
  2. Create a Helpdesk Ticket requesting training.
  3. A tool engineer will schedule a time for initial training.
  4. Practice with your mentor or another authorized user until you are comfortable with tool operation.
  5. Schedule a checkout session with a tool engineer via the helpdesk ticket system. If this checkout is successful, the engineer will authorize you on the tool.

Maintenance

Lamps changed and system alignment calibrated as needed.