ABSTRACT The paper measures the magnetic properties of NdFeB thin films developed under the effects of magnetic field. The samples exhibited a larger residual inductance, saturation magnetization and energy product than those treated without field or with weaker field. Magnetic MEMS was introduced with application of the NdFeB film to micro device such as pumps and gear transmission system

Mohammad Kilani

Pan Zheng

Professor and Dean, Ching-Jen Chen

Yousef S Haik

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DownloadProceedings of IMECE2002 
ASME International Mechanical Engineering Congress & Exposition 
November 17-22, 2002, New Orleans, Louisiana 
IMECE2002-33401 
FABRICATION OF NdFeB THIN FILM AND ITS APPLICATION IN MEMS  
 
 
Pan Zheng 
Mechanical Engineering Department Florida State 
University, Tallahassee, FL 32310 
E-mail: panzheng@eng.fsu.edu 
Mohammad Kilani 
Mechanical Engineering Department Florida State 
University, Tallahassee, FL 32310 
E-mail: kilani@eng.fsu.edu  
 
 
Yousef S. Haik 
Associate Scientist, FAMU-FSU College of Engineering 
Tallahassee, FL 32310 
E-mail: haik@eng.fsu.edu 
Ching-Jen Chen 
Professor and Dean, Florida A&M University-Florida 
State University College of Engineering, Tallahassee, FL 
32310 E-mail: cjchen@eng.fsu.edu  
 
ABSTRACT 
The paper measures the magnetic properties of NdFeB thin 
films developed under the effects of magnetic field. The 
samples exhibited a larger residual inductance, saturation 
magnetization and energy product than those treated without 
field or with weaker field. Magnetic MEMS was introduced 
with application of the NdFeB film to micro device such as 
pumps and gear transmission system. 
 
INTRODUCTION 
This study investigates the process of fabricating NdFeB 
(Neodymium-Iron-Boron) thin film on a silicon substrate of 
micro device.  The purpose of the study is demonstrating the 
feasibility of MEMS (Micro-Electro-Mechanical-Systems) 
devices driven by wireless and remote magnetic field.  In order 
to achieve the magnetically driven MEMS devices it is first 
demonstrated that the magnetic material such as NdFeB may be 
deposited in a thin film on the silicon micro device.  The study 
also shows that a sufficient force and torque can be generated 
from the coupling of the magnetic film with the external 
magnetic field generated by a high field permanent magnet. 
Compound Nd2Fe14B, is considered an ideal material 
for magnetic MEMS due to its high B-H product. Nd2Fe14B 
film has already found wide applications in compact recording 
devices, magnetic sensors, actuators and other integrated 
electromagnetic components. Much work has been done on the 
film deposition composed of this tetragonal crystalline [1,2].  
The idea of using magnetic force to drive the micro-
machine has several obvious advantages. One important merit 
is that it does not need the physical contact between the 
external magnets and the micro device. This study showed that 
the coupling of high field strength, in the order of one tesla and 
above, permanent magnet could create a substantial torque 
when the separation between the devices is within centimeters  
ed From: https://proceedings.asmedigitalcollection.asme.org on 06/29/2019 Terms of Use: or less. In magnetic MEMS, one couple of magnets is usually 
driven by an external source while the other one is the magnetic 
film coated on the micro devices, shown as figure 1. As the 
driving magnet rotates, it transfers torque to the magnetic film 
and forces the micro device to rotate once the torque overcomes 
the loading drag and internal forces [3,4]. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 1. The schematic of Magnetic MEMS 
 
DEPOSITION OF THE THIN UNDER THE MAGNETIC 
FIELD AND DISCUSSIONS 
The magnetic material, film thickness, fabricating and 
processing methods play important roles in producing high-
performance magnetic coupling. Many investigations about the 
effects of the different annealing temperature, target 
composition and processing time for different magnetic 
materials were reported in the past years [5,6]. In this work, we 
use laser-sputtering method to deposit a NdFeB thin film on the 
silicon substrate. We also study the properties of the film when 
different magnetic fields are applied on the substrate during the 
deposition. 1 Copyright © 2002 by ASME 
http://www.asme.org/about-asme/terms-of-use
DownloadThe experiment of laser-sputtering was made with the 
target Nd2Fe14B residual induction of 11,400 Gauss, coercive 
force of 10,400 Oersted, and intrinsic coercive force of 13,500 
Oersted. NdFeB films were grown on silicone substrates by 
pulsed laser deposition (PLD) employing a KrF excimer laser 
(λ=248 nm). The films were deposited in a vacuum chamber. 
The laser beam output energy is 250 mJ at a pulsed rate of 20 
Hz. The separating distance between the target and substrate is 
3cm. The substrate temperatures were set to 100°C. Film 
thickness was measured by using the profilometry and the 
magnetic properties of the film were obtained by SQUID. 
Magnetic properties of the films developed with and without 
magnetic fields were compared. 
Samarium cobalt is used as the magnet source to 
create the magnetic field during the deposition. The maximum 
operation temperature of SmCo is 350°C. Its residual induction 
of 10,500 Gauss, coercive force is 9,200 Oersted, and intrinsic 
coercive force is 10,000 Oersted. The gap between the silicon 
and the top surface of the SmCo magnet is 5 mm. The 
experiment settings and magnetic field distributions are shown 
as figure 2,3,4,5 respectively. The (a) parts of figure 3,5 are the 
magnetic field contours that perpendicular to the substrates,  (b) 
parts represent the magnetic field in the plane of the substrate 
(parallel to the surface). The Chamber vacuum of the 
deposition chamber maintains around 6 mtorr. 
 
 (a)  (b) 
Figure 2. Magnetic field distribution on the silicon 
surface induced by SmCo Permanent Magnet (setting 1). 
 
 
                (a)                  (b) 
Figure 3. Field distribution in normal direction and 
field distribution in the plane of setting 1.  
 
ed From: https://proceedings.asmedigitalcollection.asme.org on 06/29/2019 Terms of Use:  (a)   (b) 
Figure 4. Magnetic field distribution on the silicon 
surface induced by SmCo Permanent Magnet (setting 2). 
  (a)   (b) 
Figure 5. Field distribution in normal direction and 
field distribution in the plane of setting 2. 
 
Figure 6 shows perpendicular demagnetization 
hysteresis loops of the thin film deposited to the silicon 
substrate at 100°C. The magnetic properties of film samples 
measured by SQUID are cut from the middle part of the 
substrates. Compared the figure 3(a) and figure 5(a), The SmCo 
permanent magnet creates different magnetic field in normal 
direction in these two experiment settings. The magnetic field 
of former setting is larger than that of the later one in the 
central part of the substrate. That makes magnetized domains of 
the thin film easier to align the normal direction under stronger 
normal magnetic field than under weaker magnetic field. 
Similarly, figure 7 shows parallel demagnetization hysteresis 
loops of the thin film.  
 
MAGNETIC MEMS 
 Mechanical system driven remotely by magnetic field 
has special advantages for certain working circumstances. In 
the new development of blood screw pump driven by magnet 
coupling [7]. The power is transmitted to the pump from an 
outside operating motor by magnetic coupling.  The advantage 
of a magnetically driven pump is that the rotating part is sealed 
inside the pump house and self-contained. The pump works 
without a shaft that crosses its housing.  In blood flow 
applications this eliminates the possibility of blood leakage 
through the seals.  The pump can be driven remotely by 
magnetic coupling.  This allows the pump to be designed so 
that it is disposable and eliminates the possibility of bio-2 Copyright © 2002 by ASME 
 http://www.asme.org/about-asme/terms-of-use
Downloadcontamination. Those advantages will be kept when to apply 
the magnetic coupling to the micro device such as micro 
pumps. 
100°C Pa rpend ic ula r
-3.00E+03
-1.50E+03
0.00E+00
1.50E+03
3.00E+03
-6.00E+02 -3.00E+02 0.00E+00 3.00E+02 6.00E+02
Field  (Oe)
4*
3.
14
*M
 (G
)
No fie ld
Setting  1
Setting  2
Figure 6. Hysteresis loops along the perpendicular direction of 
the NdFeB thin film deposited with different magnetic field 
conditions. 
-1.50E+04
-7.50E+03
0.00E+00
7.50E+03
1.50E+04
-4.00E+02 -2.00E+02 0.00E+00 2.00E+02 4.00E+02
Field(Oe)
4*
3.
14
*M
  (
G
No field
Setting
1
 
Figure 7. Hysteresis loops along the parallel direction of the 
NdFeB thin film deposited with different magnetic field 
conditions. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 8. Typical micro engines to drive the work parts by 
electrostatic input. 
500µm
Torsional 
Ratchet 
Actuator 
Comb 
Actuator 
Transmission 
Gear train 
Work Parts
(Pump)  
 
ed From: https://proceedings.asmedigitalcollection.asme.org on 06/29/2019 Terms of Use: Figure 8 shows the typical driving actuators (micro 
engines) for MEMS application. These designs usually need 
electrical wiring circuits to provide the electrical voltage or 
current to the micro engine for creating mechanical motion or 
use micro battery cell and integrated circuit (IC) to provide the 
energy for the MEMS. The requirement of electrostatic field for 
these MEMS actuators makes the construction of MEMS 
complicated and limits their applications. For example, in some 
microsurgery, it is often desirable to avoid electrical current 
that has electron or ionic motion and also desirable sometimes 
to avoid the insertional wires. The major advantage and 
uniqueness of the magnetic MEMS is obviously the wireless 
transmission of magnetic torque that replaces the complex 
micro mechanical design to bring the electrical motive force to 
the MEMS. To let the concept of magnetic MEMS be a realistic 
practice, the magnetic force and torque induced between the 
driving and driven magnetic parts must be sufficient strong to 
transfer the mechanical motion. The NdFeB thin film deposited 
under the effect of the magnetic field can provide relative 
strong magnetization than usual one. This property enables us 
to construct some magnetic MEMS such as the spiral pump 
shown as figure 9.  
 
 
 
         
Rotating disk 
Spiral 
protrusion 
Stationary plate 
Magnetic 
Thin Film 
Outlet 
Inlet 
Pin joint 
 
Figure 9. Spiral pump with the magnetic film on the rotating 
top disk. 
 
Figure 9 illustrates a micro spiral pump works by 
rotating a disk over a spiral groove on a stationary plate with a 
close proximity. Fluid is contained in the channel created by the 
groove between the rotating disk and the stationary plate.  Due 
to non-slip conditions, a velocity profile develops in the 
channel with fluid velocity increasing from zero at the 
stationary plate to the rotating plate velocity at the top.  Viscous 
stresses on the upper and lower surfaces of the channel allow 
the fluid to be transported against an imposed pressure 
difference.  Two holes at the ends of the spiral channel provide 
the required inlet and outlet for the pumped fluid. Combing the 
basic mciro fabrication technology such as mask pattern, 
deposition and etching, The NdFeB can be deposited on the top 
of the rotating disk. Outside the micro system, put two 
permanent magnets with the motor, then we can transfer the 
torque to micro spiral pump to overcome the viscous force and 
fluid head pressure. The scale-up model shows this design is 
applicable.   
 
CONCLUSIONS 
 This paper shows the magnetic properties of NdFeB 
thin film get to be improved under the effect of magnetic field. 
A way to drive the micro device by magnetic coupling is 3 Copyright © 2002 by ASME 
http://www.asme.org/about-asme/terms-of-use
 
Downloadintroduced and discussed. The advantages of the remote driving 
system by magnetic coupling are indicated. The idea and the 
practice of using the magnetic thin film to the MEMS design 
are verified to be applicable and valuable.   
ACKNOWLEDGMENTS 
This work is supported by Sandia National Laboratory and 
Florida State University Research Foundation. 
REFERENCES 
[1] T.-S. Chin, Permanent magnet films for application in 
microelectromechanical systems, J. Magn. Magn. Mater. 209, 
2000, 75-79. 
 
[2] A.S. Kim and F.E. Camp, High performance NdFeB 
magnets, J. Appl. Phys. 79(8), 1996, 5035-5039. 
 
[3] E.P. Furlani, Formulas for the force and torque of axial 
couplings, IEEE, Trans. Magn., Vol. 29, No.5, Sept., 1993, 
2295-2301.  
ed From: https://proceedings.asmedigitalcollection.asme.org on 06/29/2019 Terms of Use:  
[4] S. Yamashita and J. Yamasaki, Anisotropic Nd-Fe-B thin-
film magnets for milli-size motor,  J. Appl. Phys. 70(10), 15 
November 1991, 6627-6629. 
 
[5] C. J. Yang, S. W. Kim and J. S. Kang, Magnetic properties 
of NeFeB thin films grown by pulsed laser deposition, J. 
Magn. Magn. Mater., 188, 1998, 100-108. 
 
[6] Wei Tang, Zhi-Qiang Jin, etc., Effect of composition on 
crystalline texture and magnetic properties of Nd2Fe14B thin 
films, J. Magn. Magn. Mater., 185 (1998), 241-245. 
 
[7] Pan Zheng, Yousef Haik, Mohammad Kilani and Ching-Jen 
Chen, Force and torque characteristics for magnetically driven 
blood pump, J. Magn. Magn. Mater.. 241 (2002), 292-302. 4 Copyright © 2002 by ASME 
 
http://www.asme.org/about-asme/terms-of-use


IMECE2002-33401 FABRICATION OF NdFeB THIN FILM AND ITS APPLICATION IN MEMS

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IMECE2002-33401 FABRICATION OF NdFeB THIN FILM AND ITS APPLICATION IN MEMS

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