Thin Film Characterization¶
You have deposited a film and need to know whether it came out right. This page is organised by the question rather than by the instrument.
What can be measured, and with what¶
| Your question | Technique | Instrument | Sample survives |
|---|---|---|---|
| How thick is it? | Ellipsometry (optical) | Ellipsometer | Yes |
| How thick is it, exactly, in cross-section? | TEM | JEOL JEM-F200 | No |
| How rough is the surface? | AFM (small patch) or optical profilometry (mm-scale) | AFM Workshop B-2 / Keyence VK-X3000 | Yes |
| Is it continuous, or has it islanded? | SEM | JEOL JSM-IT710HR | Usually |
| What is it made of? | SEM-EDS | JEOL JSM-IT710HR | Usually |
| Are there trace elements or dopants? | SIMS | Hiden SIMS Workstation | No |
| Is it crystalline or amorphous? | XRD or TEM diffraction | Rigaku SmartLab / JEM-F200 | Yes / No |
| How abrupt is the interface? | TEM cross-section | JEOL JEM-F200 | No |
| What is the grain size? | SEM, or TEM for fine grains | Both | Varies |
| Does it emit, and at what energy? | Photoluminescence | Edinburgh Instruments FLS1000 | Yes |
| Is the surface electrically uniform? | On-wafer probing | MPI TS200 | Yes |
| What does a defect look like in colour? | Digital microscopy | Keyence VHX-7000 | Yes |
| Can I copy a nano-pattern into this film? | Nanoimprint lithography | NIL Technology CNI v3.0 | Patterning, not metrology |
Recommended order¶
Run non-destructive measurements first. The film is easier to replace than the information.
- Ellipsometry - optical thickness and refractive index on a blanket area. Fast, contactless, no preparation.
- AFM - roughness across a 50 by 50 micrometre area, and step height if a patterned step is available. Ambient air, no coating. Use optical profilometry first if the survey is millimetres, not micrometres.
- SEM - continuity, morphology, defect density over a wide area, plus EDS composition. Insulating films image in low-vacuum mode without a coating.
- XRD - phase and crystallinity averaged over a large volume.
- TEM cross-section - layer thicknesses, interface abruptness, and local crystallography. Destructive, and preparation takes days, so it is the last step and reserved for questions the earlier steps could not answer.
Practical notes by film type¶
Oxides and nitrides. Insulating, so SEM either needs a thin conductive coating or low-vacuum mode. AFM needs neither, which is why roughness is usually measured before anything is coated. Coating first destroys the roughness measurement.
Metals. Straightforward for SEM with no preparation. Thin metal films roughen visibly with thermal treatment, and AFM quantifies that change where SEM only suggests it.
Polymers and organics. Beam-sensitive. Low accelerating voltage on SEM, or AFM in tapping mode to avoid dragging the tip across a soft surface.
Multilayer stacks. Only TEM resolves individual layers and their interfaces. Budget several days for TEM sample preparation - disk grinding, dimpling, then ion milling.
What to send¶
- A witness coupon from the same deposition run, if the production sample cannot be released
- The substrate material and nominal film thickness
- The deposition method and any post-deposition thermal treatment
- Whether the sample must be returned unaltered
- The decision the measurement will inform, which often changes which technique is appropriate
Thin film characterization in Flagstaff, Arizona¶
The MPaCT Lab at Northern Arizona University holds ellipsometry, AFM, optical profilometry, photoluminescence, field-emission SEM with EDS, XRD, SIMS, on-wafer probing, and analytical TEM with full sample preparation in one facility in Flagstaff, Arizona. A film can therefore move through the full sequence as a single project rather than being shipped between facilities.
The lab is open to NAU researchers, external academic users, and industry partners, on a fee-for-service basis or as a trained hands-on user.
MPaCT Lab - Building 98E, South Engineering Lab
561 E Pine Knoll Dr, Flagstaff, AZ 86001
Phone: 928-523-2343 · Email: mpct.nano@nau.edu