For example, adhesive wear occurs frequently during tribo-test under aqueous condition. Residual...
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For example, adhesive wear occurs frequently during tribo-te st under aqueous condition. Residual Stress of a-C:H Film in Humid Environment Young-Jin Lee 1), 2) , Tae-Young Kim 1) , Kwang-Ryeol Lee 1) , In-Sang Yang 2) 1) Future Technology Research Division, Korea Institute of Science & Technology, Korea 2) Department of Physics, Ewha Womans University, Korea 1000 1250 1500 1750 2000 1531.4cm -1 1538.7cm -1 T ypicalpolym eric film B enzene -100V M e th a n e -1 5 0 V M e tha n e -5 0 0 V In te n sity (a .u .) W ave N um ber (cm -1 ) G -p e a k p o sitio n M ore graphitic film 0 -200 -4 00 -6 00 -8 00 0.0 0.5 1.0 1.5 2.0 S tress(G P a) B ia s V olta g e (V ) 0 -200 -400 -600 -800 1.0 1.5 2.0 2.5 3.0 3.5 S tress(G P a) B ias V oltage (V ) C 6 H 6 CH 4 T. Ohana at al. Diamond Rel. Mater., 13 (2004) 1500 Tribo-test of a-C:H film in aqueous environment Critical issue of a-C:H film for bio-application : Film delamination is enhanced in humid and aqueous environment . a-C:H film has excellent physical and chemical properties such as high hardness, low friction, high wear resistance and chemical inertness. Various applications ranging from data storage to bio- materials have been investigated. Purposes of the Present Work • To check the possibility that the residual stress of a-C:H film is dependent on the humidity. • To characterize the humidity dependence of residual stress of a- C:H film of various atomic bond structures. • In situ stress measurement : kMO S (k-space Multi-beam Optical Se nsing) • Humidity control : 10~90% in air (±5%) step control. • Temperature : room temperature (19~26°C) • Measurement time : about 600sec for each step. • Resolution of kMOS : maximum 4km in radius (In this system 1MPa) Film Deposition • r.f. PACVD (13.56 MHz) • Precursor Gas : C 6 H 6 , CH 4 • Deposition Pressure : 1.33 Pa • Bias Voltage : -100V ~ -500V • Substrate : P-type (100) Si-wafer 525 ㎛ P-type (100) Si-wafer 200 ㎛ (5×50 ㎛ ) • Film Thickness : 500 ㎛ Result & Discussion Stress Measurement with Humid Change Residual Stress Raman spectroscopy Film Characterization -10 0 10 20 30 (M Pa) E lapsed T ime 75% 20% 90% 55% 20% D iam o n d -like F ilm Residual stress is independent of the humidity in the range fr om from 20% to 90% Max. 0 MPa Increase in the residual stress with humidity change from 20% to 90% Max. 12MPa Immediate and reversible change of the residual stress with humidity change. Observations • Residual stress of a-C:H film exhibits a humidity dependence, which is related to the atomic bond structure of the film. • In polymeric and graphitic film, the compressive residual stress increases as the humidity increases. • The residual stress of diamond- like film is independent of the humidity. • The change of the residual stress is immediate and reversible with humidity variation. The Role of Water Molecules in the Change of Stress 20 40 60 80 100 0 10 20 30 (M Pa) R e la tive H um id ity (% ) 400nm 500nm 1000nm P o lym eric film 400 600 800 1000 0 10 20 30 (M Pa) T h ickn e ss (n m ) s o f s o ff F t F t t 0 s F f t : Initial residual stress : added force : film thickness In the case of polymeric a-C:H film, for all thickness additional surface force caused by water molecule is 9.4±1.4 Nm -1 The most significant result of the present work is to show that the residual stress of a-C:H film is dependent on the humidity, which is related to the atomic bond structure of the film. The humidity dependence of the residual stress is due to the interfacial reaction with water molecule. 1) Immediate and reversible change with humidity variation 2) Change of the residual stress is inversely proportional to the film thickness Humidity dependence of the residual stress could be controlled by either changing the atomic bond structure or a simple surface treatment. Conclusions Increase in the residual stress with humidity change from 20% to 90%. Max. 16MPa Immediate and reversible change of the residual stress with humidity change. -1 0 0 10 20 30 E lapsed T ime (M Pa) 20% 50% 90% 80% 50% 20% P o lym eric F ilm -1 0 0 10 20 30 G rap h itic film (M Pa) E lapsed T ime 25% 90% 40% 20% The role of water molecules can be found by the relationship between the film thickness and variation of stress. In polymeric films, the variation of stress with humidity decreases as the film thickness increases. “Case 1. Reaction at surface” is predominant. C 6 H 6 -100V Polymeric film CH 4 –500V Graphitic film CH 4 –150V Diamond-like film From the residual stress and Raman spectroscopy, F 2 = substrate substrate F 1 Case 2. Penetration into film Case 1. Reaction at surface F 1 F 1 > substrate substrate
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Transcript of For example, adhesive wear occurs frequently during tribo-test under aqueous condition. Residual...
For example, adhesive wear occurs frequently during tribo-test under aqueous condition.
Residual Stress of a-C:H Film in Humid EnvironmentYoung-Jin Lee1), 2), Tae-Young Kim1), Kwang-Ryeol Lee1), In-Sang Yang2)
1) Future Technology Research Division, Korea Institute of Science & Technology, Korea 2) Department of Physics, Ewha Womans University, Korea
1000 1250 1500 1750 2000
1531.4cm-1
1538.7cm-1
Typical polymeric film
Benzene -100V
Methane -150V
Methane -500V
Inte
nsity
(a.
u.)
Wave Number (cm-1)
G-peak position
Moregraphitic film
0 -200 -400 -600 -8000.0
0.5
1.0
1.5
2.0
Str
ess
(GP
a)
Bias Voltage (V)0 -200 -400 -600 -800
1.0
1.5
2.0
2.5
3.0
3.5
Str
ess(
GP
a)
Bias Voltage (V)
C6H6 CH4
T. Ohana at al. Diamond Rel. Mater., 13 (2004) 1500
Tribo-test of a-C:H filmin aqueous environment
Critical issue of a-C:H film for bio-application : Film delamination is enhanced in humid and aqueous environment.
a-C:H film has excellent physical and chemical properties such as high hardness, low friction, high wear resistance and chemical inertness. Various applications ranging from data storage to bio-materials have been investigated.
Purposes of the Present Work• To check the possibility that the residual stress of a-C:H film is dependent on
the humidity.
• To characterize the humidity dependence of residual stress of a-C:H film of various atomic bond structures.
• In situ stress measurement : kMOS (k-space Multi-beam Optical Sensing)
• Humidity control : 10~90% in air (±5%) step control.
• Temperature : room temperature (19~26°C)
• Measurement time : about 600sec for each step.
• Resolution of kMOS : maximum 4km in radius (In this system 1MPa)
Film Deposition
• r.f. PACVD (13.56 MHz)
• Precursor Gas : C6H6, CH4
• Deposition Pressure : 1.33 Pa
• Bias Voltage : -100V ~ -500V
• Substrate :
P-type (100) Si-wafer 525 ㎛ P-type (100) Si-wafer 200 ㎛ (5×50 ㎜ )
• Film Thickness : 500 ㎚
Result & Discussion
Stress Measurement with Humid Change
Residual Stress Raman spectroscopy
Film Characterization
-10
0
10
20
30
(
MP
a)
Elapsed Time
75% 20%90%55%
20%
Diamond-like Film
Residual stress is independent of the humidity in the range from from 20% to 90% Max. 0 MPa
Increase in the residual stress with humidity change from 20% to 90% Max. 12MPaImmediate and reversible change of the residual stress with humidity change.
Observations• Residual stress of a-C:H film
exhibits a humidity dependence, which is related to the atomic bond structure of the film.
• In polymeric and graphitic film, the compressive residual stress increases as the humidity increases.
• The residual stress of diamond-like film is independent of the humidity.
• The change of the residual stress is immediate and reversible with humidity variation.
The Role of Water Molecules in the Change of Stress
20 40 60 80 100
0
10
20
30
(
MP
a)
Relative Humidity (%)
400nm 500nm 1000nm
Polymeric film
400 600 800 1000
0
10
20
30
(
MP
a)
Thickness (nm)
s o f so
f f
F t F
t t
0
sF
ft
: Initial residual stress
: added force
: film thickness
In the case of polymeric a-C:H film, for all thickness additional surface force caused by water molecule is
9.4±1.4 Nm-1
The most significant result of the present work is to show that the residual stress of a-C:H film is dependent on the humidity, which is related to the atomic bond structure of the film.
The humidity dependence of the residual stress is due to the interfacial reaction with water molecule.
1) Immediate and reversible change with humidity variation2) Change of the residual stress is inversely proportional to the film
thickness
Humidity dependence of the residual stress could be controlled by either changing the atomic bond structure or a simple surface treatment.
Conclusions
Increase in the residual stress with humidity change from 20% to 90%. Max. 16MPaImmediate and reversible change of the residual stress with humidity change.
-10
0
10
20
30
Elapsed Time
(
MP
a)
20%50%90%80%50%20%
Polymeric Film
-10
0
10
20
30
Graphitic film
(
MP
a)
Elapsed Time
25%90%40%20%
The role of water molecules can be found by the relationship between the film thickness and variation of stress.
In polymeric films, the variation of stress with humidity decreases as the film thickness increases. “Case 1. Reaction at surface” is predominant.
C6H6 -100V Polymeric film
CH4 –500VGraphitic film
CH4 –150VDiamond-like film
From the residual stress and Raman spectroscopy,
F2
=substrate substrate
F1
Case 2. Penetration into filmCase 1. Reaction at surface
F1 F1
>
substrate substrate
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