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Rudolph Ellipsometer AutoEL III, ellipsomter

The Rudolph Ellipsometer AutoELIII (single wavelength 6328Å) allows measurement of the thickness and refractive index of one or two thin transparent films on a substrate.

Picture and Location

 Rudolph

This tool is located at A3 on the Lab Map:

 

Process Capabilities

Cleanliness Standard

 The Rudolph Ellipsometer appears in all three equipment groups (clean, semiclean, and gold).


 

How to Become a User

  1. Read all material on the SNF website concerning the Rudolph Ellipsometer.
  2. Contact SNF training contact on the Equipment Summary page.

Operating Procedures

 

Single wavelength 6328Å

Introduction:

This procedure will describe how to obtain accurate thickness measurements of various thin films. The ellipsometer is best used on a single light penetrable film such as nitride on a silicon substrate or oxide on gallium arsenide; two layers can be measured on the ellipsometer (you should know the thickness and refractive index of the lower layer). The instrument can give extremely accurate measurements, but the user must know roughly the thickness of the film to be measured, as the calculated results are cyclic.

Instructions:

Initialization (main manual page 6 - 21):

  1. Turn on the AutoEL AC power with the key lock switch and wait 15 minutes for warm-up.
  2. If the power is already on: RESET (every 24 hours)
  3.   “Insert Sample
    Place a control wafer ( ~1000 Å oxide on silicon) on the stage.
    Press Continue
  4.   “Align Sample,(page 6-18)
    The spot to be measured needs to be clean and smooth, i.e. doesn’t scatter light.
    Adjust sample height to reflect light beam into analyzer entrance aperture.
    Use the z-axis and tilt adjustments to center the focusing light: the white circle is in the middle of the black ring.

    Press Continue

  5. Up comp:   push it up Cont
  6. Down comp:   push it down Cont

Program setup:

1. Press LEARN   Enter
2. Prog File 01 Enter
3. Measuring Routine (page 4 - 42) speed: slow; accuracy: high 02 Enter
4. Calculating Routine (page 4 - 50)    
  to calculate T and N for one unknown transparent film on Si substrate 10 Enter
5. Printer Format (page 4 – 31), TU, delta, PSI 2 Enter
6. Serial Output Format 0 Enter
7. Enter ID Option 0 Enter
8. Spec Thickness (film thickness in Å)                                              approx.   Enter

 

1. Press RUN 91  
  Pattern            (page 4 –14)                                                          manual    
  (Don’t use “Auto”, use manual and “Align” between each measurement!)    
  Program (= Prog File #2 above) 01 Enter
2. Position Sample: use joystick, align sample see #4 above   Cont
3. Shutdown                                                                                                              ESC

                                                                     

Helpful Hints:

  • Measure the SiO2 control wafer before measuring "real" samples. The result should be about 1000 angstroms in the very center.
  • The PSI result should not be below 20.

    N = refractive index
    NU = refractive index, upper film
    NL = refractive index, lower film
    NS = refractive index, substrate

    List of refractive indices at wavelength 6328A:

     

    Si = 3.858
    SiO2 = 1.46
    Si-Nitride = 2.0
    Low stress nitride = 2.3
    Pt = 2.5 - 2.53

    T = thickness
    TU = thickness, upper film
    TL = thickness, lower film
    KS = extinction, substrate

    Poly on Quartz:

    Calculating Routine: 31 - 33
    KS = 0.0
    NS = 1.46

    Substrate GaAs:

    Calculating Routine 12 or 13:
    NS = 3.823
    KS = 0.378

 

Comments:

  • Wear facemask to protect clean wafers!
  •  Beam Diameter and Spot Sizes page 3 -19

Printer Test:

RUN

00            99            Enter

7                    Enter

E will printout until:

            Escape

Shutdown Procedures:

  • Shutdown: ESC
  • Clean up around the area.
  • Report problems and notify the responsible people of any machine problems.

 

 

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