ETREMA Products, Inc.
Integration of Thin-Film Galfenol with MEMS Cantilevers for Magnetic Actuation Rajneeta R. Basantkumar, Bethanie J. H. Stadler, William P. Robbins and Eric M. Summer* Department of Electrical and Computer Engineering, University of Minnesota * ETREMA Products, Inc
Neeta Basantkumar
www.ece.umn.edu/users/stadler
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ETREMA Products, Inc.
Outline Motivation Experimental Fabrication of Galfenol films Calculation of Magnetostriction
Galfenol Film Results Fabrication of Cantilever Beams Conclusions Neeta Basantkumar
www.ece.umn.edu/users/stadler
[email protected]
ETREMA Products, Inc.
Motivation Study properties of Galfenol at microscale MEMS devices Sensors
From NSWC-Carderock Division courtesy M. Wun-Fogle, J.B. Restorff, A.E. Clark, et al.
- magnetic field - chemical - acoustic
Medical (eg: opthalmology) Telecommunication Etc Neeta Basantkumar
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ETREMA Products, Inc.
RF-Sputtered Galfenol Films Glass substrates Galfenol targets (18.4%) Sputtering power – 60-100W, 20W increment Deposition time – 30 and 60 mins Glass flow rate – 10-50 sccm, 10 sccm increment Deposition rate – 2-4 nm/minute
Neeta Basantkumar
www.ece.umn.edu/users/stadler
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ETREMA Products, Inc.
Capacitance Bridge
Neeta Basantkumar
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ETREMA Products, Inc.
Capacitance Bridge b C2
C1 a
c
Vo
C4
C3 d
Vin
C1 and C2 – Fixed capacitors C3 – Variable capacitor C4 – Sample (Unknown)
Neeta Basantkumar
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ETREMA Products, Inc.
Calculation 1 ∆C Magnetostrictive coefficient, λm = k t f C02 k = [Esε0wtf2 (1+ νf)] / (EfL)
*
Es = Young’s Modulus of Glass Substrate = 65.0 GPa Ef = Young’s Modulus of Film (Galfenol) = 72.4GPa - 86.3GPa** ε0 = Dielectric constant of insulator (air) = 8.854x10-12 F/m νf = Poisson’s ratio of film (Galfenol) = 0.3 νs = Poisson’s ratio of substrate (Glass) = 0.17 w = width of substrate (glass) = 18 mm ts = thickness of substrate (Glass) = 0.125 mm L = length of substrate (Glass) = 18 mm tf = thickness of film (Galfenol) C0 = initial capacitance before magnetic field ∆C = | Cf - C0| = capacitance difference before and after magnetic field * ε = Ef(1- ν s)/Es(1-σf) 3 t l 2
Deflection, d =
f
ελ m
t s2
*E. Klokholm, IEEE Trans. Magnetics. 12 819 (1976) **E. M. Summers, A.T. Snodgrass, J.D. Jonathan, J.C. Slaughter, Proc. SPIE 5387 448 (2004)
Neeta Basantkumar
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ETREMA Products, Inc.
Outline
Motivation Experimental Fabrication of Galfenol films Calculation of Magnetostriction
Galfenol Films Results Fabrication of Cantilever Beams Conclusion Neeta Basantkumar
www.ece.umn.edu/users/stadler
[email protected]
ETREMA Products, Inc.
Crystallography
[110] orientation of Galfenol thin films Neeta Basantkumar
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ETREMA Products, Inc.
Sample Summary λm (ppm)
Deflection (µm)
30.1
35.0
0.14
75
21.4
32.3
0.19
30
133
19.4
16.3
0.17
20
60
92.4
26.6
109
0.81
80
20
60
146.5
23.8
147
1.71
100
20
60
211.7
19.5
35.6
0.25
80
30
60
130.8
23.3
60.0
0.55
100
30
60
195.2
15.2
120
1.86
Power (W)
GasFlow (sccm)
Time (mins)
tf (nm)
60
20
30
49
80
20
30
100
20
60
% Ga
Examples of experimental data showing the thickness, concentration of Ga, and magnetostriction Neeta Basantkumar
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ETREMA Products, Inc.
Magnetic Properties 1.25
Fe 0.75
0.25 M/Ms
60W60min 20sccm -0.25
80W60min 20sccm
-0.75
100W60min 20sccm
-1.25 -50
-30
-10
10
30
50
Field (Oe)
The hysteresis loops showing the dependence of coercivity on the forward power Neeta Basantkumar
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ETREMA Products, Inc.
Composition and Coercivity 35
2.5
%Ga for 20sccm,60 mins
25
1.5
20
15 50
60
70 80 90 Forward Power (W)
100
0.5 110
Coercivity (mT)
% Ga
30
%Ga for 20sccm,30 mins
Coercivity for 20sccm,60 mins
Atomic % Ga and coercivity dependences on the forward power Neeta Basantkumar
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ETREMA Products, Inc.
Recall – For bulk Galfenol
From NSWC-Carderock Division courtesy M. Wun-Fogle, J.B. Restorff, A.E. Clark, et al.
Neeta Basantkumar
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ETREMA Products, Inc.
Double Peak Trend – λs vs. %Ga 160 140
Magnetostriction (ppm)
120 100 80 60 40 20 0 0
5
10
15
20
25
30
35
%Ga
Neeta Basantkumar
www.ece.umn.edu/users/stadler
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ETREMA Products, Inc.
Outline Motivation Experimental Fabrication of Galfenol films Calculation of Magnetostriction
Galfenol Films Results Fabrication of Cantilever Beams Conclusions Neeta Basantkumar
www.ece.umn.edu/users/stadler
[email protected]
ETREMA Products, Inc.
Fabrication of Cantilever Beams Photolithography Reactive Ion Etch Remove PR
Galfenol
Si3N4
Si
Sputter Beam Material Wet Etching Neeta Basantkumar
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ETREMA Products, Inc.
Conclusions
Successfully deposited Galfenol thin films [110] on glass cover slides
Composition of films controlled by
forward power and magnetic properties controlled by the composition
Magnetostriction up to 147 ppm Fabricated cantilever beams Neeta Basantkumar
www.ece.umn.edu/users/stadler
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ETREMA Products, Inc.
Acknowledgements Office of Naval Research (ONR) for funding through ETREMA Products, Inc., Ames, Iowa through grant number N00014-05-C-0165
Prof. Joey Talghader for providing the cantilever masks
Neeta Basantkumar
www.ece.umn.edu/users/stadler
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ETREMA Products, Inc.
Questions?
Neeta Basantkumar
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ETREMA Products, Inc.
Sizes vary from 180microns to 950 microns
Neeta Basantkumar
www.ece.umn.edu/users/stadler
[email protected]
ETREMA Products, Inc.
Neeta Basantkumar
www.ece.umn.edu/users/stadler
[email protected]
ETREMA Products, Inc.
Neeta Basantkumar
www.ece.umn.edu/users/stadler
[email protected]
ETREMA Products, Inc.
Neeta Basantkumar
www.ece.umn.edu/users/stadler
[email protected]
