RF Sputtering Technique
Presented at the
Nanomaterials Workshop for
High School Science Teachers
University of Tulsa
Summer 2004
Facilitators:
Dr. Winton Cornell
Dr. Saibal Mitra
Lab Assistants:
Michael Deshazer
Lauren Hutter
CurriculumWritten by:
Lindsay Jones
Deer Creek-Lamont High School
Lamont, Oklahoma
Table of Contents
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
Introduction-------------------------------------------------------------- Page 1
Basic sputtering process diagram-------------------------------------- Page 2
Nanomaterials applications--------------------------------------------- Page 3
University of Tulsa sputtering apparatus----------------------------- Page 3
Operation procedure for sputtering apparatus----------------------- Page 4
Analysis of substrate plates-------------------------------------------- Page 4
Conclusions-------------------------------------------------------------- Page 4
References---------------------------------------------------------------- Page 5
I.
Introduction:
Sputtering, commonly known as physical vapor deposition, is a physical process by
which atoms of one material are deposited onto another material called the substrate. It occurs
when atoms of one material become ionized and move at high speed to the surface of the other
material, called the target, to “knock” individual atoms of the target material free, allowing
them to drop onto the substrate to coat it. An apparatus commonly known as an RF Sputter is
used to form substrate plates upon which to grow materials such as Nanocarbontubes.
The RF sputter derives its name form using energy waves in the radio wave spectrum range.
This process is widely used by industry to form coated materials that are used in various
applications of materials science. Many of materials used daily have been produced by the
sputtering method. Some examples of these materials are: semiconductors, microchips,
mirrors, colored glass, and cosmetics.
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II.
Basic Sputtering Process Diagram: (Graphics obtained from http://icknowledge.com/ )
1. An atom collides with an energized particle to become ionized.
2. In the reactivity chamber the
ions and electrons moving
toward oppositely charged
plates.
3. The high speed charged
ions knock the target atoms
loose, allowing them to drop
onto the substance to be
coated.
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III.
Nanomaterial Applications:
In the field of Naonmaterial Technology, extremely small structures ( ~ 1-100M ) are
formed by this process. The sputtering technique lends itself well to this field because it
involves a process using individual atoms. This allows for the coating of small substrates
which are used in the building of nanomaterials such as nanocarbon tubes.
The field of Nanomaterials focuses on building small servo motors, data storage
systems, structural components, and composite materials with unique properties.
IV.
RF Sputtering Apparatus used at the University of Tulsa:
Magnet
Source
Vacuum Plasma
Chamber
Target
Plate
Shield
Shield
Substrate
Gas
Supply
Power
Supply
Vacuum
Pump
Substrate
Holder
Thickness
Monitor
Sputter Coat Monitor
3/
V.
Operation of the RF Sputter Coating Apparatus:
1. Place the material source used for the deposition of desired atoms on the target plate.
2. Swing the shield around to cover the target plate until plasma field is ready.
3. Place the substrate plate to be coated on the substrate plate on the bottom of the
chamber.
4. Use the vacuum pump to evacuate the air from the plasma chamber.
5. Turn on the power supply to activate the magnets.
6. Turn on the gas supply.
7. Initiate the plasma energy source.
8. Monitor the rate of milliamps to obtain the desired sputter pattern.
9. Stop process after desired time is reached.
10. Turn off gas supply.
11. Turn off power source.
12. Pressurize the plasma chamber.
13. Remove substrate plate.
VI.
Analysis of Substrate Plate:
The substrate plates formed by the RF Sputtering process can be analyzed for
the desired effect by different means. One method is to directly observe the substrate
plate by using a Scanning Electron Microscope to observe the surface of the substrate.
This would allow the experimenter to see such features as uniformity of deposition,
irregularities in the substrate surface, irregularity in the deposition pattern, and
deposition of foreign particles. The scale bar on the Scanning Electron microscope
would also allow the observer to determine the approximate size of the particular
feature being observed.
Another method of analyzing the substrate plate would be to use the Atomic
Force Microscope. This instrument would give the experimenter a graphic view of the
uniformity of the surface of the substrate plate and as well as irregular features. It
would also allow the experimenter to determine the thickness of the area of deposition
compared to the surface of the substrate plate.
A third method of analyzing the substrate plate would be to subject it to X-Ray
Diffraction. This instrument would provide the experimenter with an analysis of the
materials in the substrate plate by giving a characteristic diffraction pattern for each
material in the substrate plate.
VII.
Conclusions:
RF sputter deposition has many practical uses both in industrial and scientific
applications. In the field on Nanotechnology, working with small objects to achieve the
desired pattern of deposition and thickness of a substrate requires advanced technology
to be able to produce substrates that are usable for a nucleated growth surface for
desired substances such as Nanocarbontubes. This technology is rapidly expanding to
the point where it will be possible to produce the desired Nanomaterials within the
future.
4/
References
1. Magnetron Sputtering, http://www.gencoa.com/tech/whatsputtering.html
2. Overview of Sputtering, http:// www.angstromsciences.com/technology/sputtering.htm
3. Sputtering,
http://www.mse.vt.edu/faculty/hendricks/mse4206/GaAs/GAsaTEK/metallization/sputteringa.htm
4. New Advances in RF Sputtering, http://www.aultimut.com/rf_sput.html
5. Sputtering, http://en.wikipedia.org/wiki/Sputtering
6. Magnetron Magnetic Enhancement, http://www.soleras.com/magntrn/enhance.htm
7. Fundamentals of Sputter Deposition, http://icknowledge.com/
8. Sputtering, http://www.fact-index.com/s/sp/sputtering.html
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