Operating Procedure
Filmetrics F20
Thin-Film Analyzer
Abbreviated Lab Manual
Revision 1.0
June 4, 2008
Filmetrics F20 Thin-Film Analyzer
The Filmetrics F20 (shown in Figure 1) is fiber optics spectrometer that can be used to determine the
thickness, and/or optical constants (n and k) of semiconductor and dielectric thin films. Such films must be
optically smooth, and within the thickness range set by the system configuration requirements listed in
Table 1.
Commonly measured films include semiconductor process such as oxides, nitrides, resists, polysilicon,
optical coatings, and polyamides. Please note that the thickness of metal or optically rough films cannot be
determined using the Filmetrics F20.
This abbreviated lab manual provide a set of instructions on how to determine the thickness of a layer of
silicon dioxide deposited on a silicon substrate.
Table 1: Thickness ranges
F20
F20-UV
F20-NIR
F20-EXR
F20-CP
F20-HC
F20-XT
Thickness Range
Thickness Range when
measuring n and k
150 Å to 5 µm
30 Å to 20 µm
1000 Å to 250 µm
150 Å to 250 µm
1000 Å to 50 µm
1000 Å to 50 µm
1000 Å to 5 µm
500 Å to 5 µm
3000 Å to 10 µm
1000 Å to 10 µm
N/A
1000 Å to 5 µm
2000 Å to 450 µm
N/A
Fiber Optic Cable
F20 Spectrometer
PC Monitor showing a
measurement
Stage Arm
Sample or Reference (face up)
Figure 1: Filmetrics F20
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Filmetrics F20
Preparation
1.
2.
Turn on the light source located in front of the computer at least fifteen minutes before taking a
measurement.
Lauch the FILMeasure program by double clicking on the “FILMeasure” icon on the computer
desktop (Figure 2).
Figure 2: “FilMeasure” icon on the computer desktop.
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3.
Take a Base line Measurement
a.
b.
Type in the Sample ID and the Operator
Make sure that the selected structure is “SiO2 on Si” as shown in Figure 3.
i. If not, select the ““SiO2 on Si” structure using the pop-up menu (Figure 3).
Figure 3: make sure that the selected structure is “SiO2 on Si”.
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Filmetrics F20
c.
Make sure that the software is set in “Reflection Mode”, and that the “Show Measured
Spectrum” box is checked as shown in Figure 4.
Figure 4: make sure that the software is set in “Reflection Mode”, and that the “Show Measured Spectrum” box is checked.
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d.
e.
Click on “Setup”, and select “Data Acquisition”. The menu shown in Figure 5 will be
displayed.
Select silicon “Si” as the “Reference and Dark”.
Figure 5: “Setup”, and “Data Acquisition Menu.
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Filmetrics F20
f.
Place the “Si Reference Wafer” under the probe, as shown in Figure 6.
Figure 6: the “Si Reference Wafer” under the probe.
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g.
Press the “Take Reference” button, so that the reflectance spectrum of the Si reference
can be taken, as shown in Figure 7.
Figure 7: the reflectance spectrum of the “Si Reference Wafer”.
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Filmetrics F20
h.
Remove the “Si Reference Wafer” and press the “Take Dark” button. Make sure that
both the options “Subtract Dark” and “Use Reference” are activated (Figure 8).
Figure 8: Steps necessary to take a “Dark Reference”.
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i.
Remove the “Si Reference Wafer” and press the “Take Dark” button. Make sure that
both the options “Subtract Dark” and “Use Reference” are activated (Figure 8).
Figure 9: Steps necessary to measure the thickness of the SiO2 on Si Test Wafer.
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Filmetrics F20
j. Remove the “Si Reference Wafer” and press the “Take Dark” button. Make sure that
both the options “Subtract Dark” and “Use Reference” are activated (Figure 8). Also
make sure that the value for the thickness “d” of the SiO2 layer is 7331.0 Å (Figure 8).
Figure 10: Steps necessary to measure the thickness of the SiO2 on Si Test Wafer (continued).
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Measuring Thickness
1.
Select film structure to be measured from the “STRUCTURE” list on the main screen (#10 in
Figure 13 – APPENDIX A)
**If structure to be measured doesn’t exist refer to “Editing Film Structures” section on pages 1621 in the operation manual**
2.
Edit the film structure
a. Click “EDIT STRUCTURE” button (#11 in Figure 13 – APPENDIX A)
b. A dialogue box will appear
c. Check the unit box and make sure it matches the units that you will use to enter your
guess for the thickness (#13 in Figure 14 – APPENDIX A)
d. Enter your best guess for the thickness of film to be measured
(#9 in Figure 14 – APPENDIX A)
e. Make sure the medium is set on air
f. Select material to be measured (#11 in Figure 14 – APPENDIX A)
g. Select substrate that material is on
h. Make sure only “d” is checked (#6 in Figure 14 – APPENDIX A)
i. Select “OPTIONS” tab (#2 in Figure 14 – APPENDIX A)
j. Make sure only the “Grid Search for thickness” in “Solving Details” tab is checked
k. Make sure only “Reflectance” is checked in “Measurement Type” tab
l. Select the “Save” button (#10 in Figure 14 – APPENDIX A)
m. Select the “OK” button
3.
Make the Measurement
a. Place sample on stage where the light is gleaming on the place of measurement as shown
in Figure 11: .
b. Click on the “Measure” button (#8 in Figure 13 – APPENDIX A)
c. The Measurement will be displayed on the Main Window (#6 in Figure 13 –
APPENDIX A)
Figure 11: A wafer with Si + SiO2 ready to be measured.
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Filmetrics F20
Post Measurement
1. Assure Proper Measurement
Figure 12: Correctly Measured and Calculated Reflectance Spectra
a.
b.
2.
3.
If the measurement was successful, the minima and the maxima of the calculated reflectance (the
red line on graph) will coincide in wavelength with the minima and maxima of the measured
reflectance (the blue line on graph). In most cases they will not overlap, but will be separated in
amplitude.
If the measurement doesn’t appear to be successful, refer to the “Troubleshooting” section on page
51 in operation manual.
Turn off light source
Shut down the computer
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APPENDIX A
1
2
3
4
6
7
8
9
10
11
12
13
15
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Figure 13: FILMeasure Main Window
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
File: Standard Windows “File” menu for saving and retrieving data, printing, etc.
Edit: The “Edit” menu is used for viewing and editing the material library.
Set up: Used to set up reflectance acquisition parameters and the graphic display.
Acquire: For starting and stopping continuous reflectance acquisition and data measurement.
Convenient for setting up hardware.
Graphical display for measured and calculated reflectance, as well as measured optical constants.
Change display limits by double-clicking in the display area. A right click while the curser is
within the graphical display activates a blue line (one click for measured curve) and re line (2
clicks for calculated curve) for easy reading of cursor values in the main FILMeasure window.
Keyboard up/down and right/left arrows move the line to a desired location.
The measured film thickness is displayed here.
The baseline measurement sequence is initiated by pressing the “Baseline” button.
This button causes a reflectance spectrum to be acquired and then analyzed in one step.
Performs analysis on the displayed reflectance spectrum.
Used to select the film structure that is to be measured.
This is where the selected film structure is described, and the analysis i parameters are set.
Used to select the information displayed in the results box below.
The results box summarizes the most recent measurement results.
Statistical tabulation of all measurement results is accessed by pushing this button.
Complete calculated results of the most recent measurement are accessed by pushing this button.
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Filmetrics F20
2
3
4
1
13
5
12
6
11
9
8
10
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Figure 14: Edit Structure Window
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
The name of the film structure is listed here.
Advanced measurement parameters can be accessed by clicking on the “Options” tab.
Constraints on the possible measured values are selected here.
Author, as defined by user login name, and structure modification date are indicated here.
A very robust thickness measurement routine is enabled by selecting this box
The values to be measured are selected by checking the appropriate boxes.
“OK” closed the “Edit Structure” box, retaining any changes made. Changes will not be
permanently saved unless “Save” or “Save As” is selected. The “Cancel” button closes the “Edit
Structure” box without retaining changes.
Known film roughness for films not being measured, and the initial guess for the film(s) being
measured are entered in this column.
Known film thicknesses for films not being measured, and the initial guess for the film(s) being
measured are entered here.
The structure can be saved as a new structure, deleted, or changes can be saved.
The film layers are listed here. Common films can be selected from the pull-down menus.
Layers can be added using this button. Up to 8 layers may be present in the structure.
The thickness (length) units are chosen here. The choices include nanometers (nm, 10^-9 m),
microns (µm, 10^-6m), angstroms (A, 10^-10m), and
kilo-angstroms (kA, 10^-7 m)
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