特集2 日仏マイクロメカトロニクス国際共同研究組織(LIMMS

HOSHI Yasuo

IKEDA Kokichi

KAWAKATSU Hideki

KIM Beomjoon

MICHIHATA Masahiro

MUTSUO Tae

NAKAZAWA Tomonori

NIINO Toshiki

YAMAMOTO Akio

UTokyo Repository

研究速報 : Making five atomic force microscope
for 200,000yen each : A student project
journal or
publication title
生産研究
volume 56
number 1
page range 121-123
year 2004
URL http://hdl.handle.net/2261/00078635
doi: info:doi/10.11188/seisankenkyu.56.121
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研 究 速 報
56巻1号 (2004)
1. Introduction
At the Graduate School of University of Tokyo, a lecture and
technical training course was newly opened from the summer term
of year zOO3.Its aim was acquisition of the basics of scientific
instrumentation, circuitry and programming. Eighteen students
supervised by four professors built five atomic force micro-
scopes with a budget of just under 200,000 yen per microscope.
The paper describes the details of the microscope, how the
course was organized,and what was achieved.
2. Purposes
The atomic force microscope (AFM) can acquire images by
scanning the trp and measuring the displacement of the cantilever
caused by atomic force between the tip of the cantilever and the
sample surface (Fig. 1). The AFM can also be applied to insula-
tors, is an advantage over the scanning tunneling microscope.
This course's purpose was to learn the principles of AFM, ana-
log circuitry, programming by CJanguage and basis of
microcomputer conffol.
SEISAN‐KENKYU
速
3. Instrumentation
Operational mode of conventional AFM
Can be classified as follows,
(1) Contact modet) -Tips contact surfaces of samples and figures
of surfaces are measured by displacement of cantilevers.
(2) Tapping mode2) -Tips contact surfaces of samples periodi-
cally and figures of surfaces are measured by amplitude shift of
cantilevers.
(3) Non-contact mode') -Tips are vibrated close to surfaces of
samples and figures of surfaces are measured by frequency shift of
cantilevers.
We applied contact mode as the operation mode of AFM that we
made, because contact mode AFM is the basic mode and is easv to
implement.
We applied an optical lever methodo) to measure displacement
of cantilevers. We show the schematic of an optical lever method
in Fig. 2. An optical lever method is the measuring way of can-
tilever's behaviors by irradiating the back of the cantilever with a
laser and detecting the reflection with a photodetector. The spot of
reflection moves with the cantilever's displacemelt caused by sur-
報究
Making Five Atomic Force Microscope
for 200,000 yen each
― A student proJect―
Tac MUTSUO*,Tomono五NAKAZAWA*,TOshiki NIINO*,Akio YAMAMOTO**,
BeomJoon KIM*,Yasuo HOSHI*,KokichiIKEDA*,Masahiro MICHIHATA*and Hideki KAWAKATSU*
* Institute of Industrial Science, The University of Tokyo
* *Graduate 
school of Engineering, The University of Tokyo
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$u  r  f ace
Fig. I Schismatic of principle of AFM.
Fig. 2 The AFM head composed in the class.
研 究
56巻1号 (2004) SEISAN―KENKYU
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Fig. 3 Schematic of the system.
face topography. Thus the output power of a photodetector
changes, and the surface comrgation could be obtained.
In this way, the principle and the composition of the optical
lever method is simple and can be low-cost. We applied a four-seg-
ment photodiode as a photodetector.
We show the entire composition of the AFM which we made in
Fig. 3. The analog circuit processes the signals from AFM head
and the H8 microprocessor receives the signals and sends them to
PC. The rough and fine positoneres of AFM head are composed of
piezoelectric element and are controlled by the H8 microprocessor
via the analog circuit.
In this course, the parts which students made are,
(1) Data acquisition and scanning conffol programs: We made
data acquisition programs based on sample programs given by pro-
fessor. The program for PC saves signals which are sent from HB
microprocessor. And, the program for H8 microprocessor inter-
faces signal-processing circuit with PC and controls driving of
piezoelectric element on AFM head.
(2) Signal processing circuit: This circuit calculates 4-segment
photodiode signals to deflection (AFM) and friction (FFM) signals.
The circuits adapt the signal voltage for PC. The compositions are
I/V converters, adding operators, an integrator, and amplifiers.
(3) AFM head: This is a main component of this AFM unit.
(4) Samples: We made micro-patterns on Si chips by etching Au
deposited Si wafers. The mask is SAM (Self assembly monolayer)
with a PDMS stamp. Cleaved mica was used for atomic level
imaging.
4. Course contents and cost
This class was held 180min a week, a total of 14 times. Fig. 4
shows the course content and its flow. The class was divided into
5 groups which consisted of three to five students. Each group
made one AFM. Fig.5 is the scene of the class.
Total cost was 200,000 yen each AFM including PC, machine
parts, electrical circuits, etc. Its approximative breakdown is
shown in Table 1.
Fig.4
Fig. 5 Scene of the class and group photo.
Thble I Approximative breakdown.
Item Price L¥」
PC 50.000
H8Microcomputr Kit 5.000
Sisnal processing circuil 281450
Walker driver circuit 17.443
AFM head 97.152
sampled 1.840
Toセコl 1991885
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122
Cl rcui t  Classes
I-|d Cunrrerter
I nt egrat nr
Addine $peratnr
Anrp l i f p r
Prsgraming Classes
0 r i r r i n e  $ l a l k e r
F r e .
$cann ing  Frg .
t l ieger  Frg ,
Lecture ahout
samp I Bs
l|lakine fiamples
56巻1号 (2004) SEISAN¨KENKYU
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5. Results
We observed surface of samples with AFM we made. Au
deposited on silicon wafer, crystal plane of mica and SAM were
used as samples. The results of observation on Au deposited and
mica are shown in Fig. 6 and Fig.7 respectively.
The scan area size was 300nm X 300nm in Au observation. We
could confirm typical gold comrgations.
We observed cleaved mica surface with attenuator to narrow
scan area.It was 30nm X 30nm. This narrowing was done to use
the greatest dynamic range of the AFM considering D/A output of
H8 microcomputer is 8 bit. D/A output was used as driving voltage
of the stage so that it moves in256 steps. Hence it is necessary to
narrow the scan area when we observe smaller patterns with this
AFM. In Fig. 7 ,there are 63light and shade patterns in single hor-
izontal row. Number of the patterns should be 60 when scan was
done 30nm X 30nm area because crystal distance of mica is
0.5nm. Therefore, we considered that crystal face of mica could be
observed.
It was difficult to observe SAM because of PZT driving voltage,
dynamic range, etc. scanning rougher plane,lager area is an issue
in the future.
6. Conclusion
For the pu{pose of learning principles of scientific instru-
inents, a class of technical exercises including mechanics, optics,
electronics, measurements and control was held at the graduate
school, the University of Tokyo. A contact mode AFM was chosen
as the system to be implemented. Au deposited on silicon wafer
and cleaved mica were observed. The class was held three hours a
week, a total of 14 times, conducted with four professors and eigh-
teen students. The total cost was just under 200,000 yen per AFM.
Five AFMs were made in total. Good mechanical design and
optics made the low-cost AFM highly performant. It was an effec-
tive course where students learned about teamwork,leadership and
rewarding moments. Class recommences April 2004.
Acknowledgement
We thank TODAI SEIKEN-KAI for financial support.
(Manuscript received, November 17 ,2003)
References
1) Binnig G., C. F. Quate, and Ch. Gerber 1986 Atomic Force
Microscopy. Phys. Rev. Lett.56: 930
2) Zhong Q.,Innis D., Kjoller K., Elings V.8., 1993 Surf. Sci. 290,
L688
Martin Υ,Williams C.C.,Wickramasinghe H.K.,1987J.Appl.
Phys.61:4723
4) Gerhand M., Nabil M.A. 1988 Apple. Phys. Lett. 53: 1045
Fig.7 Cleaved mica (30 nm X 30 nm).
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Fig. 6 Au deposited (300 nm X 300 nm).


研究速報 : Making five atomic force microscope for 200,000yen each : A student project

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研究速報 : Making five atomic force microscope for 200,000yen each : A student project

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