Comparson of Elastic Modulus of Very Thin DLC Films …：的非常薄的类金刚石薄膜的弹性模量比较…

150 100
100
166
50 20
0 0 100 200 300 400 500 600
Thickness (nm)
Biaxial Elastic Modulus
200
Residual Compressive Stress (GPa)
Biaxial Elastic Modulus (GPa)
3.0 2.5 2.0 1.5 1.0 0.5
x
c
4 2D 2t
Stain of the Buckled Thin Films (II)
x
1 W 2 x
2
x
1
2
1 W
2 dx
2 2 x
x
Ao
2
From
c
4 2D 2t
,
E
1
3 1 2
t 2 2
c
c o
1
1
3 1
Ao
2
0
t
1EAo2oc
Advantages of This Method
– Simple – Completely Exclude the Substrate Effect – Can Be Used for Very Thin Films
✓ The possibility of elastic modulus measurement in very thin film
1525
1520
0 50 100 150 200 250
0 50 100 150 200 250
V / P1/2 (V/mTorr1/2)
V / P1/2 (V/mTorr1/2)
b
b
Biaxial Elastic Modulus
200
Residual Compressive Stress (GPa)
Thickness (nm)
Biaxial Elastic Modulus
200
Residual Compressive Stress (GPa)
Biaxial Elastic Modulus (GPa)
3.0 2.5 2.0 1.5 1.0 0.5
0
50 100 150 200 250
V / P1/2 (V/mTorr1/2) b
Self Delamination of DLC Films
• K.-R. Lee et al., Diam. Rel. Mater. 2 (1993) 208. • M.-W. Moon et al., Acta Mater., 50 (2019) 1219.
Key Idea of the Method
Preparation of DLC Bridge by Micro Fabrication
DLC film Deposition ( on SiO2 )
DLC Patterning
SiO2 Isotropic Wet Etching
Wet Cleaning
Strain Estimation
Microstructure of DLC Bridges
• ta-C films showed insignificant structural evolution during the initial period of deposition.
Comparison of Elastic Modulus of Very Thin DLC Films Deposited by
r.f.Biblioteka BaiduPACVD and FVA
Jin-Won Chung, Churl-Seung Lee, Dae Hong Ko*, Jun-Hee Hahn** and Kwang-Ryeol Lee
G-peak Position (c -m1)
200
150
100
100
166
233
50
20
0 0 100 200 300 400 500 600
Thickness (nm)
1560
1550
233
1540
166
100
1530
20
1520 0
300 600 900 1200
Thickness (nm)
Schematic Film Structure
Applications of DLC Film
High Residual Compressive Stress of DLC Films
DLC Coating
• Causes the Instability of the Coating • Affects the Physical Properties in Some Cases
0
35 V 300 V
100 200 300 400 500
Thickness (nm)
Elastic Modulus of ta-C film
Residual Compressive Stress (GPa) Biaxial Elastic Modulus (GPa)
7 6 5 4 3 2 1 0
Biaxial Elastic Modulus (GPa)
3.0 2.5 2.0 1.5 1.0 0.5
0
50 100 150 200 250
V / P1/2 (V/mTorr1/2) b
150 100
50 20
0 0 100 200 300 400 500 600
Thickness (nm)
Biaxial Elastic Modulus
Biaxial Elastic Modulus (GPa) G-peak Position (c -m1)
200
Si Substrate
150
100
50
Si Substrate
0
0 100 200 300 400 500 600
Thickness (nm)
Si Substrate
1560
1550
1540
0 100 200 300 400 500 600
Negative Bias Voltage (V)
900 800 700 600 500 400 300 200 100
0
GND 35 V 300 V
100 200 300 400 500
Thickness (nm)
Raman Spectra
16 nm 86 nm 91 nm 132 nm 238 nm 302 nm
100 200 300 400 500 600
N egative B ias V oltage (V )
2 50
Nanoindentation t>1.0 ㎛
2 00
1 50
1 00
50
0 0 100 200 300 400 500 600 700 800
N e g a tiv e B ia s V o lta g e (V )
0
50 100 150 200 250
V / P1/2 (V/mTorr1/2) b
150 100
100
166
233
50 20
0 0 100 200 300 400 500 600
Thickness (nm)
G-peak Position of Raman Spectra
Biaxial Elastic Modulus (GPa)
Strain Measurement
E / ( 1-) ( G P a ) P la n e S t ra in M o d u lu s ( G P a )
Elastic Modulus for Various Ion Energies
200
150
100
50 B ridge M ethod
0 F reehang M ethod
150mm
C6H6, 10mTorr, -400V, 0.5mm
Strain of the Buckled Thin Films (I)
z
D
4W x 4
ct
2W x 2
0
x
at x
W
, W
0
2
x
c
2A0
c
at x , 2
W
W
0
x
oc (1 E)x
W
(x)
A o 1 cos
2
1530
1520 0
233 166 100
20
300 600 900 1200
Thickness (nm)
Synthesis of ta-C Films
• ta-C films on Si (100) Wafer • Vb : from 0 to –500V
Elastic Modulus of ta-C film
– Sufficient Adhesion
– df << ds
– ds << R
b f
Y fd s 2R
b f
f
3 Y fd f Y sd s
Measurement of Curvature
K d sin
dx
Key Idea of the Method
E 1
For Isotropic Thin Films
200
Residual Compressive Stress (GPa)
Biaxial Elastic Modulus (GPa)
3.0 2.5 2.0 1.5 1.0 0.5
0
50 100 150 200 250
V / P1/2 (V/mTorr1/2) b
150 100
100
50 20
0 0 100 200 300 400 500 600
Residual Compressive Stress (GPa) Biaxial Elastic Modulus (GPa)
7 6 5 4 3 2 1 0
0 100 200 300 400 500 600
Negative Bias Voltage (V)
900 800 700 600 500 400 300 200 100
E 1
For Isotropic Thin Films
Measurement of Residual Stress
ds df
R
f
1 6R
Y
s
d
2 s
df
1
Efdf Esds
f
1 6R
Y
s
d
2 s
df
for
df
ds
• Assumption
– 1-D Treatment of Elastic Equilibrium
Intensity (A.U.)
1000
1500
2000
2500
Raman Shift (cm-1)
Summary
• Presently suggested method for the elastic modulus measurement enabled us to compare the mechanical properites and thus the atomic bond structures of very thin amorphous carbon films.
E
1
Ao
2
o
Preparation of Free-overhang by Anisotropic Substrate Etching
DLC film Deposition
Cleavage along [011] Direction
Si Etching (by KOH Solution)
Wet Cleaning
Residual Stress & G-peak Position of Raman Spectra
Residual Compressive Stress (GPa)
G-peak Position (cm-1)
3.0 1555
2.5
1550
2.0
1545
1540 1.5
1535
1.0
1530
0.5
Future Technology Research Division, Korea Institute of Science and Technology * Department of Ceramics, Yonsei University
** Korea Research Institute of Standard Science
T h ick n e s s (n m )
a-C:H, C6H6 -400V
ta-C (-50Vb)
J.-W. Chung et al, Diam.Rel. Mater. 10 (2019) 2069.
Synthesis of DLC Film by r.f.-PACVD
• RF PACVD (13.56MHz) • Precursor : CH4 • Vb/ P1/2 : 20 ~ 233 Vb/mTorr1/2 • Substrate : P type (100) Si • Film Thickness : ~ 50nm
B ia x ia l E la s t ic M o d u lu s (G P a )
Elastic Modulus of Very Thin Films
1 00
75
50 25
0
on S i on W / S i o n S iO / S i
2
2 00 4 00 6 00 8 00 10 00 12 00