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General Calibration Procedure

1. TCAL background and tips

TCAL calibrates small feature sizes by using the device's inherent (self-) heating together with a known temperature of an adjacent reference region.

For TCAL to work well, the device pulse needs to be long enough to produce measurable heating, but short enough to limit heat spreading and thermal expansion to roughly the top 10–100 µm of the sample.

Keep the following in mind when planning a TCAL measurement:

  • Higher pulse power produces a larger temperature change for short pulses and gives better signal-to-noise ratio (SNR).
  • Longer averaging time per frame lowers noise and improves the quality of the resulting calibration images.
  • A pulse that is too long shows more edge effects from thermal expansion; a pulse that is too short is too spatially localized to support a uniform-temperature assumption. Choose a pulse width between these extremes for your device.

2. Stage/chuck-based calibration with SanjVIEW and TCAL software

This workflow uses a temperature-controlled chuck to establish a hardware calibration reference, then applies it to a pulsed "Movie Mode" image series of the device using the standalone TCAL software.

A. Perform the hardware calibration in SanjVIEW 7

  1. Open SanjVIEW 7 from the desktop (SV7.exe).
  2. Center the sample in the Project Manager and focus on the device of interest.
  3. Uncheck the "INT Vo 20mA Range" box (green = checked, grey = unchecked).
  4. Set up the thermocouple probe, if used: a. Click File → Options → Hardware. b. Set "TC 1 Type" to "K". c. Close the window.
  5. Click Calibration.
  6. Configure Hardware settings: a. Set "High Temp" and "Base Temp" for your chuck ramp (a "High Temp" of 75 °C and a "Base Temp" of 120 °C are typical starting values — see the Qorvo notes below). b. Turn "TC-100 State" ON. c. Click SET to initialize the chuck to the base temperature. d. Set "Use TC-100 Chuck Sensor" OFF (grey) to use an external thermocouple probe as the temperature reference, or ON (orange) to use the chuck's own sensor if no external probe is available.
  7. Configure Timing/Illumination settings: a. Set "Stage Heating Time" to 40. b. Set "Image Averages" to 50.
  8. Perform 3D Alignment — Focus ROI: a. Using the rectangle tool, select a region on the CCD image over a unique, identifiable feature (an edge or scratch mark works well). b. Click Focus ROI to set the selection as your region of interest. c. Wait for the region to focus; the Focus ROI indicator turns green when complete.
  9. Note: the selected ROI region is displayed in green. Use the magnifying glass tool to zoom — hold Shift to zoom out, Shift+click to zoom in.
  10. Perform 3D Alignment — Capture Reference: a. Once the ROI is focused, click Capture Reference to set the selected region as your reference region. b. Wait for the Capture Reference indicator to turn green. c. If available, set initial Focus Tolerance, Alignment %, and Vibration Filter values — the corresponding indicators turn green when the image is within range. Increasing Alignment % and decreasing the Vibration Filter improves alignment accuracy. A previously saved reference image can also be loaded to simplify alignment.
  11. Click Start Measurement: a. Choose a save path and file name (for example, C:\Data\Cal_120_75C). b. Wait for "Loop Iterations" to change from 0 to 1. c. Click Save Data. d. Click Return to Project Manager.

B. Record a Movie Mode image series of the pulsed device

  1. Click File → Options → Software and set "Movie Mode Length" to "Very Long (30 sec)". Close the Options window.
  2. On the TC-100 tab, set the chuck Set Point (for example, 80 °C) and confirm "TC-100 State" is ON.
  3. Click Movie Mode.
  4. Set the device drive voltage (for example, "Voltage Out"/"Voltage to Device (V)") and click Update V to apply it.
  5. Set the DUT pulse width (for example, "DUT Pulse (s)") and click Update Timing.
  6. Click Start Movie. The status bar fills in green as each averaging cycle completes and continues averaging until you exit Movie Mode. You may leave SanjVIEW running to average longer for more accurate results — you will need to save and reprocess again afterward.
  7. Choose (or create) a save path and file name for the image series. Movie Mode saves a series of 105 images, so use a dedicated folder to keep the files together.
  8. Wait until the status bar completes at least one full averaging cycle, then click Save Image.

C. Generate the coefficient map in TCAL software

Open the TCAL software from the desktop, or from C:\Program Files\SanjVIEW\TCAL.exe. If TCAL.exe is not present in that folder, download the current software using the EZ500 Software Update Instructions guide.

  1. Click File → Browse Folder and select the first image of the Movie Mode series you saved above. Wait for the progress bar to finish loading.
  2. Select the region of interest: a. Select a bright, uniform region of interest (ROI) close to the area you want to measure. Choose an area that does not span multiple material types and where the material is uniform within the box. b. Set Calibration Method to "Calibrated from File". c. Click 2d. Load CAL Map and load the calibration file saved during the hardware calibration step above.
  3. Click 3. Generate Coefficient Map and wait for the progress bar to finish.
  4. Save the result: a. Choose a file save path and name. b. Click 4. Save Calibration Image.

3. Transient (pulsed) calibration with SanjANALYZER+

This workflow performs the calibration directly from a fast electrical pulse and its thermal decay, using SanjANALYZER+, without a separate chuck-heated calibration step.

A. Acquire the data

  1. Set up the device for high-speed pulsed bias (a rise/fall time under 1 µs is preferable).
  2. Apply a device pulse — around 50 µs is typical, adjusted for the power and size of the device.
  3. Set a starting delay of 50 µs and an end time of 260 µs; only the thermal decay portion of the curve is needed.

B. Process the data

  1. Select and open the first image of the series in SanjANALYZER+.
  2. Draw a region of interest (R1) to monitor the temperature of the hottest area of the device (typically the gate or channel).
  3. Draw a second region of interest (R2) over a region of known thermoreflectance coefficient (for example, a gold pad or other known material).
  4. Go to Data → TransientCAL.
  5. Click Process Data.
  6. Set the low end of the time range to a point where a uniform-temperature assumption is valid across the imaged area (60–70 µs in a typical example) and set the high end of the range (400 µs in a typical example).
  7. Enter a path and filename, then click Save Cth Map.

The saved TCAL (Cth) map can be loaded and used as a normal calibration map for point-by-point calibration, the same as a standard calibration map.

4. Choosing a calibration method and reference sensor

When generating a coefficient map, you generally choose a calibration method and a calibration sensor/reference:

Calibration methods

  • Single Emissivity — use this when you know the emissivity of a reference region on the device (for example, a black-painted area, an emissivity sticker, or similar coating). You enter that emissivity value and it is used to calibrate the rest of the image.
  • Calibrated from File — use this when you have already obtained emissivity/coefficient data from a SanjVIEW hardware calibration. You load the saved calibration map file rather than entering a value directly.
  • Calibrated with TCAL — use this when you use the TCAL software/method to obtain emissivity from the device's own transient heating rather than from a separate calibration step.

Calibration sensors/reference regions

  • R1 Region on Graph/Image — uses a user-selected region on the captured image or graph as the reference.
  • External Thermocouple — uses an externally placed thermocouple probe as the reference temperature sensor.
  • External Sensor — uses another externally placed sensor as the reference.

General procedure for any of the above, once you have determined your method and sensor:

  1. Click File → Browse Folder and select the first image in your Movie Mode (or pulsed) series.
  2. Select your known calibration region (ROI), calibration method, and calibration sensor as described above. If entering emissivity directly, a value around 0.95 is typical for black paint or an emissivity sticker.
  3. Click 3. Generate Coefficient Map.
  4. Choose your file save path and click 4. Save Calibration Image.