FILMETRICS F20 User manual

Operations Manual
for the
FILMETRICS F20
Thin-Film Analyzer
Revision 6.9.2
Copyright © 2012 by Filmetrics, Inc.
All Rights Reserved

Welcome
What is the F20 used for?
The Filmetrics F20 is used to measure the thickness and optical constants (nand k) of dielectric and
semiconductor thin films. Measured films must be optically smooth and within the thickness range
set by the system configuration requirements specified in Performance Specifications. Commonly
measured films include semiconductor process films such as oxides, nitrides, resists, and poly-
silicon, optical coatings such as hardness and anti-reflection coatings, flat panel display films such
as polyimides, resist, and cell gaps, and the various coatings used in CD and DVD manufacture.
Warning: Accurate measurements require suitable recipe settings and a valid baseline. Improper system setup or
an aged lamp may also lead to errors. It is the user’s responsibility to ensure that this instrument is being used
properly for its intended purpose. Please contact Filmetrics support for assistance with any questions.

Safety, Maintenance and Care
This symbol indicates information or instructions that must be read and carefully followed to pre-
vent hazards, injury to the operator, or damage to the instrument.
This symbol indicates a potential shock hazard. Areas marked with this symbol should be serviced
by a trained service technician.
This symbol indicates that the product conforms to the WEEE (Waste in Electrical and Electronic
Equipment) Directive 2002/96/EC.
This symbol indicates that the product meets the applicable EU safety, health and environmental
protection directive requirements.
This label indicates the Model Number and Serial Number of the instrument. This information may
be necessary when contacting Filmetrics for assistance.

Disclaimer:Use of this instrument in a manner inconsistent with the information and directions
included in this manual may impair the protections designed into the product resulting in danger to
the operator or damage to the instrument
Installation Location: When deciding on a location for the instrument, ensure that the instrument
in installed in a well-ventilated location. Enclosing the unit, or blocking the vent holes, may impair
the performance of the instrument of damage the internal components.
Cleaning:The need for periodic cleaning of the system is based on the cleanliness of the envi-
ronment in which the system is installed. Only the external surfaces are to be cleaned. Cleaning
and maintenance of all internal components is to be performed by a trained service technician. Do
not use aerosol, or spray, cleaners as they may contaminate the sensitive optical surfaces on the
instrument.
Before performing any service on the instrument ensure that the main power is disconnected.
Cleanroom, or low lint, wipes should be used to wipe down the system. A mixture of Isopropyl
Alcohol (IPA) and De-ionized Water (DI H2O) at 70% DI H2O: 30% IPA is to be used for clean-
ing. Undiluted IPA may be used, if the 70:30 DI and IPA mixture is not available, but extra care
must be taken. Avoid using stronger solvents, such as acetone, as these may compromise the sur-
face finish.
Avoid excessive pressure on any surface when cleaning. Excessive force may bend a component,
which would damage the system, or cause the system to be out of alignment.
Start with the top of the system and work down. Use slow motions, in a straight line, from the back
to the front of the surface being cleaned. Change the cleaning wipe periodically to avoid re-depos-
iting material back onto the surface being cleaned. Allow all cleaned surfaces to dry completely
before restoring power to the system.

CE Mandated Warnings
Please read the following instructions carefully to prevent potential shock or fire hazards. This
manual should be retained for future use
Bitte lesen Sie die nachstehende Anleitung sorgfältig durch um Stromschlag und Feuergefahr zu
vermeiden. Diese Betriebsanleitung sollte für späteren Gebrauch sorgfältig aufbewahrt werden.
Preghiamo di leggere accuratamente, le sequenti Instruzioni, per evitare Prossiomi Incendi e
Correnti.
Shock Hazard - Do Not Enter
Achtung Hochspannung - Nicht Berühren
Attenzione Corrent-Forte - Prego non toccare
The front panel’s switch is not the power disconnect device. The power cord should be removed
after use.
Der Kippschalter an der Vorderseite unterbricht nicht die Stromzuführung. Das Stromkabel sollte
nach Gebrauch aus dem Gerät herausgezogen werden.
L’interutore nella parete frontale non blocca le Corrente. La Corrente viene.
Never expose the unit to water or liquids. Avoid direct sun.
Bringe das Gerät nicht mit Wasser oder einer anderen Flüssigkeiten in Berührung. Vermeide
direkte Sonneneinstrahlung.

Evitare contatto con acqua oppure liquidi Infiammabili al Macchineggio. Auche entrate di Sole.
Do not insert any objects into the unit.
Keinen Gegenstand in das Gerät einbringen. Do non inseriamo any obietta into gli unità.
Non mettere ogetti dentro la Macchina.
Do not use near open flame or heat.
Das Gerät nicht in der Nähe einer offenen Flamme oder Hitze benutzen.
Non mettere la Macchina vicino a fuochi oppure Riscaldamenti.
The unit should never be enclosed or blocked.
Das Gerät darf nicht eingeschlossen oder blockiert werden.
La Macchina non chinderla per nessun motivo.
Connect unit only to a properly measured supply. Use only three wire cord which is provided
with the unit.
Schließen Sie das Gerät nur an eine ordnungsgemäss vermessene Stromsversorgung an.
Verwende nur ein dreiadriges Kabel, wie es auch mit dem Gerät ausgeliefert wird.
Montare solo con misura normata. Adoperando solo 3 cavi elettrici cosi come e fornita la
Macchina.

Software Overview
The way that light reflects off of a thin film is determined by the characteristics of the film, such as
its thickness, optical constants, and roughness. The F20 is able to determine thin-film char-
acteristics by first carefully measuring the amount of light reflected from the thin film over a range
of wavelengths (i.e., by measuring the reflectance spectrum), and then analyzing this data by com-
paring it to a series of calculated reflectance spectra. Most of the features of the FILMeasure soft-
ware that runs the F20 can be divided into reflectance acquisition and reflectance analysis
functions. The following pages outline the main features of the FILMeasure software.
The basic steps for any F20 measurement are selecting and editing the film structure, taking a base-
line measurement, and then making and evaluating the measurement. The details of each of these
steps are explained below, followed by descriptions of other FILMeasure functions.
Measure Tab
1. Standard Windows File menu for saving and retrieving data, printing, etc.

2. The Edit menu is used for viewing and editing the material library.
3. Used to Setup various parameters and the graphic display.
4. For starting and stopping continuous reflectance acquisition and data measurement.
5. Used to access the Help,Diagnostic and Support functions of the software.
6. Shows that the Measure tab is currently selected.
7. Used to select the History tab.
8. This is the thickness result from the measured spectrum.
9. This button causes spectra to be acquired and analyzed.
10. The baseline measurement sequence, which is required before measurements are made, is ini-
tiated by pressing the Baseline button.
11. This button analyzes the selected spectra.
12. This is used to select Recipe settings that correspond to different samples to be measured.
13. This is where the Recipe (the film stack definition and data acquisition and analysis settings) is
set. Hundreds of recipes can be saved and later recalled.
14. This box provides more details about the calculated thickness, as well as any additional param-
eters that were solved for, including Roughness,nand k, and Non-Uniformity as well as the
Goodness of Fit (GOF).
15. Graphical display for spectra. A click of the right mouse button while the cursor is within the
graphical display activates a blue line (one click for measured 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 graph limits can be changed by double-clicking on the graph display. The Horizontal Axis
Minimum and Maximum fields are used to control the wavelength range displayed on the screen.
Use the Vertical Axis Minimum and Maximum fields to control the vertical-axis display. Check
the Autoscale Maximum checkbox to activate y-axis autoscaling. The lower value is always 0 for
autoscaling; the maximum y-axis upper limit is 5000. Changing the Vertical Axis will change the
reflectance axis, the Vertical Axis 2 will change the transmittance axis. The axes can be set to dis-
play in percent or as a decimal value (100% = 1).

Graph Options can be accessed and edited by double-clicking on the main graph window.
16. This allows the user to enter information about the Operator and Sample for tracking purposes.

History Tab
1. Standard Windows File menu for saving and retrieving data, printing, etc.
2. The Edit menu is used for viewing and editing the material library.
3. Used to Setup various parameters and the graphic display.
4. For starting and stopping continuous reflectance acquisition and data measurement.
5. Used to access the Help,Diagnostic and Support functions of the software.
6. Used to select the Measure tab.
7. Shows that the History tab is currently selected.
8. Selecting the Measurement Trend tab will allow the user to see a plot of the measurement
results versus measurement number.

When the Measurement Trend tab is selected in the History window, the right side of the screens graphs the
results.
9. Displays the measurement results for the currently selected measurement number.
10. Displays the spectra for the currently selected measurement number.
11. Saves the history file.
12. Deletes the currently selected spectra.
13. Clears the history file.
14. Copies the selected data to the clipboard.
15. Sends the selected spectra and the associated recipe back to the measure tab.
16. Displays the statistics of all past measurements.
17. Shows all measurements numbers. Selecting a measurement number will cause the associated
spectrum and measurement results to be displayed on the right side.

Edit Recipe Window
The Edit Recipe Window is used to define the film stack and to set analysis and acquisition param-
eters.
A recipe defines the film to be measured and its approximate thickness, any other films present,
and the quantities to be measured:
1. Open a saved Recipe file.
2. Clear all settings and start a New Recipe.
3. Save the current recipe settings.
4. Save the current recipe settings as a new file.
5. Delete the current recipe.

6. Select from different recipes saved under the Recipes folder.
7. Author, as defined by user login name and recipe modification date are indicated here.
8. Additional solving options for Composition,Thickness, and Non-Uniformity can be hidden or
revealed by pressing the + or - buttons.
9. Constraints on the possible measured values are selected here.
10. OK closes the Edit Recipe box, retaining any changes made.
11. The Cancel button closes the Edit Recipe box without retaining changes.
12. Apply will not be permanently saved unless Save or Save As New… is selected.
13. These tabs allow the users to navigate to the various other recipe settings.
14. The thickness units are chosen here. The choices include angstroms (Å, 10e-10 m), nanometers
(nm, 10e-9 m), kilo-angstroms (kÅ, 10e-7 m), microns (µm, 10e-6 m), mils and microinches.
15. Adds a new layer.
16. Deletes the selected layer
17. This pulldown menu allows the user to select the desired material file. Also, left-clicking on the
text will open the Search Materials dialog box.
Editing Film Structures
The description of the nominal film structure, as well as the measurement parameters, is specified
in the Edit Recipe dialog box. Dozens of different film structures and their measurement spec-
ifications may be saved using the Edit Recipe dialog box.
The Edit Recipe dialog box is accessed with the Edit Recipe button on the Measure Tab. The
Edit Recipe dialog box lists an initial guess at the specifications of the film structure to be meas-
ured. These specifications include the name of the film structure (which identifies it in the Recipe:
list), the number of films in the structure, the specifications of individual films, and the quantities to
be measured.
Adding, Changing, or Deleting a Structure
When the Edit Recipe dialog box is opened, it shows the stored specifications of the structure
selected from the Recipe: list, along with any changes made since the program was started.
Changes to the structure selected can be permanently stored by making the desired changes and

then clicking on Save Changes. New structures may be added to the Recipe: list by opening the
Edit Recipe dialog box, setting the desired specifications, and then clicking on Save As. Similarly,
a structure may be deleted (removed from the Recipe: list) by clicking on the Delete Recipe but-
ton.
Edit Recipe>Film Stack window.

Film Stack
The Film Stack tab is used to define the film structure, as well as the starting guesses and con-
straints for thickness, nand k. This is also where you determine your analysis method, Grid,FFT ,
or None, as well as any Non-Uniformity that may be present in the sample. Additional options for
Composition,Thickness and Non-Uniformity can be selected or hidden by using the + and - but-
tons.
Setting Up a Film Stack
When measuring a layer, the specifications (d,n,k, and roughness) of the known films (including
the incident medium and substrate) must be entered into the proper fields in the Edit Recipe dialog
box, as well as initial guesses for the values to be measured. The refractive index (n) and extinction
coefficient (k) values for common materials can be selected automatically with the pull-down
menus on the left-hand side of the Edit Recipe dialog box, or by clicking on the box and using the
Search function.
If a material is being measured which is not present in the material library there are three possible
approaches:

a) choose a material in the library that is similar.
b) if the material is transparent (an insulator), select “Enter Refractive Index Value” from
the material list and enter a value for the refractive index (nwill automatically be varied by
FILMeasure to account for dispersion effects, with the entered value being n at 632 nm).
c) in the Edit>Material Library… dialog box, enter the refractive index values for nand kas
a function of wavelength and save the files so that they may be selected as in a). See Creating
and Editing nand kFiles for more information.
Choosing the Films to be Measured
To measure a film's thickness, check the Vary box on the right-hand side of the Film Stack field
in the Edit Recipe dialog box. When no boxes are checked, the theoretical spectrum for the spec-
ified layer stack and thicknesses will be displayed.
As with most measurements, the uncertainty of the measured data increases as the number of simul-
taneously measured values increases. Thus it is best to provide as much information about the film
structure as possible.
Constraints
By setting constraints, the user can limit the possible values of the measured film properties. The
constraints are set in conjunction with the values entered in the Range dialog box for thickness.
For example, if the initial guess of the measured thickness of a film is 100 nm and the thickness
constraint is set at 50%, FILMeasure will only consider possible thicknesses in the range 50 nm to
150 nm. The constraints for nand kare set using the nand kdialog boxes under Composition.
These boxes are only visible when the Composition option is expanded. You can select between
constraining by a percent of the thickness guess, or by a selected thickness by clicking on the % or
measurement unit above the constraints dialog box. Constraining the measurement range can speed
up the measurements and can also help exclude non-physical solutions.
nk Model
When measuring nand kfor a film, the general dependence of these values upon wavelength must
be specified. This dependence is determined by the type of material to be measured. For example,
insulators, semiconductors, and metals all have a unique type of nand kwavelength dependence.
Dozens of models for these different dependencies have been proposed and used over the years.
FILMeasure uses a few of the most versatile and accepted of these models. For insulators, the Cau-
chy model is used, for semiconductors, either the Amorphous or Bridge-Lorentzian model, and for
metals, the Drude model. There are also a number of special-purpose models for specific appli-
cations. These models, and starting coefficients values, are selected automatically when a material
is chosen from the Material lists in the Edit Recipe dialog box. Other models may also be spec-
ified by selecting them from the nk Model pulldown menu under the Composition tab which is
accessed by right clicking on the Vary checkbox.

Fourier search for thickness
The FFT option in the thickness dropdown is an alternative option to let FILMeasure choose an ini-
tial thickness for analysis. The Fourier Transform method analyzes the oscillations present in the
spectrum and determines the film thicknesses based on the periodicity of those oscillations. It is
somewhat less robust than the Grid method, but is better at finding the correct thickness in cases
where the shape of the initial theoretical spectrum is different than the measured data (i.e., the reflec-
tance spectrum is non-ideal in some way) or in cases where there is more than one film thickness is
being measured.
Grid search for thickness
There are a number of methods that FILMeasure can use to determine thickness. None is perfect –
each is a different trade-off between speed, accuracy, and robustness (i.e., the ability to find the
best solution among many that are nearly as good). Because thickness can vary over many orders
of magnitude and many near-solutions exist, it is often best to use a very robust method to get close
to the best solution, and then let a more accurate method take over. One very robust method is the
Grid method, which can be activated by selecting the Grid option in the thickness dropdown. The
Grid method searches the entire allowed thickness range (as defined by the initial guess and the
constraints) to find the best initial thickness. However, on some very complex multilayer spectra, it
is possible for the Grid method to become confused and give the wrong answer. In such cases it is
best to use the Fourier Transform method to determine initial thicknesses, or to provide them
manually.

Non-Uniformity
Selecting this option enables modeling of thickness non-uniformity within the measurement spot.
An initial guess for Non-Uniformity must first be made, and then solving can be enabled or dis-
abled by toggling the check box.

Search
The Search Materials dialog box is accessible by left clicking on a material name in the Edit
Recipe > Film Stack tab. This feature allows the user to search for materials by using either the
materials name, or a keyword for a certain class of materials. The search function will also show a
brief Description of the material selected, as well as any Synonyms or Keywords related to the
material file. The Similar Materials box will list any materials that may have similar optical prop-
erties.

Analysis Options
Correct setting of the following options will help ensure accurate measurements. Many of the
options are set automatically when film information is supplied in the Edit Recipe dialog box, and
all of them can be saved so that subsequent measurements can be made as quickly and easily as
possible. If Robust (Adaptive; Thickness Only) or FFT (Thickness Only) is checked, only the
Data Selection settings will be accessible.
Data Selection
Wavelength Range
This sets the wavelength range of data that is to be analyzed. It may be either the range displayed
on the current graph or a fixed range. Wavelength range may also be changed by dragging the
ends of the gray bar near the bottom of the graph area.
Smoothing
This function performs wavelength-dependent boxcar averaging on the measured spectra. This can
improve signal-to-noise levels and can filter out oscillations that correspond to optical thicknesses