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Ellipsometer
Gaertner Scientific Corporation
Model No. 1169-AK
Manufacture Date: July 1988


Contact Information:
  Faculty Contact:   Aaron Hawkins
  Staff Contact:   Jim Fraser
  Student Contact:   Michael Olson

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  1. General Information and Usage
    1. This equipment is used to measure the thickness and index of refraction for thin dielectric films.
  2. Measurement Procedure
    1. See Picture for Label
    2. Sequential List
      1. Initially set polarizer drum (P1) to read 85 and the analyzer drum (A1) to read 45. Adjust GAIN CONTROL until meter reads midway between and full scale (150 to 200).
      2. Rotate analyzer drum (A1) slowly within the red numbered segment (0 to 90) and set this drum to yield the lowest reading on the extinction meter.
      3. Rotate polarizer drum (P1) slowly within the red-numbered segment (315 to 135) and set this drum to yield a new and even lower meter reading. If meeting reading exceed 110, adjust GAIN CONTROL to bring maximum reading below 100. The numerical value on the meter is not important. Only the settings of the polarizer and analyzer drums yielding the lowest readings on the extinction meter are significant.
      4. Return to the analyzer drum and rotate the drum slowly to drive the meter pointer to a new and still lower position. The analyzer must be within the red numbered segment (0 to 90). If not, rotate the polarizer drum to a different setting within the red numbered segment (315 to 135). If the meter reading falls below 25 (1/8 full scale), use the GAIN CONTROL to bring the meter indicator reading up to 50.
      5. Return to the polarizer drum and rotate the drum slowly to drive the meter pointer to a still lower position. Work back and forth between new analyzer and polarizer drum settings until the lowest possible meter reading is obtained. These drum settings will correspond to true extinction.
      6. Record the first analyzer drum reading (A1) and then the first polarizer drum reading (P1) at extinction.
      7. Add 90 to the first polarizer drum reading (P1); i.e (P1+90). Rotate the polarizer drum to this sum.
      8. From 180, subtract the first analyzer drum reading (A1); i.e (180-A1). Rotate the analyzer drum to this difference.
      9. Slowly rotate the polarizer drum to obtain the lowest reading on the meter. (It will not be necessary to rotate the drum more than a few degrees).
      10. Slowly rotate the analyzer drum to obtain a still lower meter reading. Adjust GAIN CONTROL to bring meter pointer to approximately 50.
      11. Return to the polarizer drum and rotate the drum very slowly, attempting to drive the meter pointer to a lower reading. Set polarizer drum at setting at which the lowest meter reading is obtained.
      12. Return to the analyzer drum and rotate the drum very slowly, attempting to drive the meter pointer to a lower reading. Set polarizer drum at setting at which lowest meter reading is obtained.
      13. Work back and forth between new polarizer and analyzer drum settings to obtain final lowest reading on meter.
      14. Record analyzer and polarizer readings (A2 and P2). This second set of values will vary slightly from the calculated P1+ 90 and 180-A1 values from steps h and I, but should not differ by more than 4 for accurate measurements.
  3. Data Conversion
    1. A set of five graphs and a document consisting of Ellipsometric Tables for measuring single-layer, transparent (non-absorbing) film thickness on a silicon substrate are supplied with L117 Ellipsometer as Standard Data Conversion accessories.
  4. Film Thickness and Index Graphs
    1. Film thickness and index graphs 1,2 and 3 are used for measurement taken at 70 angle of incidence.
    2. Film Thickness and Index Graph 1
      1. See Chart 1
    3. Film Thickness and Index Graph 2
      1. See Chart 2
    4. Film Thickness and Index Graph 3
      1. See Chart 3
    5. Film Thickness and Index Graph 4
      1. See Chart 4
    6. Film Thickness and Index Graph 5
      1. See Chart 5

Ellipsometry Calculator
This calculator uses the P1, A1, P2, and A2 angles found using an ellipsometer to calculate delta, psi, index and thickness. A "Time and Rate Calculator" is also included; it uses the thickness calculated from the Ellipsometry calculator along with the test wafer growth time and desired thickness to calculate the rate of growth and the time needed to grow the desired thickness at that rate.


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