1. 금속이 혼입된 비정질 탄소막 (Me-DLC)에서의 응력감소 거동 ;실험적 분석과 제일원리계산
23, Sep., 2005
KAIST
열역학분과 심포지엄
금속이 혼입된 비정질 탄소막 (Me-DLC)에서의 응력감소 거동 ;실험적 분석과 제일원리계산
한국과학기술연구원 미래기술연구본부
최정혜, 안효신, 이승철, 왕애영, 이광렬

2. Diamond-like carbon (DLC) films
High hardness
High wear resistance
Low friction coefficient
Optical transparency
Chemical inertness
Smooth surface
Bio-compatibility
Protective coating
Bio materials
Video
Head Drum
Coronary
Artery Stent
Hard disk
Hip Joint

3. Disadvantages of DLC films
High residual compressive stress
(6~20 GPa)
poor adhesion
Hard disk
Before deposition
After deposition
Substrate bending
Delamination
M. W. Moon, Acta Mater., (2002).

4. Stress and sp3 bond fraction
Hardness

5. To reduce residual scomp in DLC films
Substrate biasing
Post-annealing
Metal atom incorporation
; Ti, W, Mo, Cr, Al….

6. W-incorporated DLC films
1.9 at % W
Mechanism ?
Not fully understood yet !!!
A.-Y. Wang APL (2005).

7. Purpose of this work DLC Diamond ; distorted sp3 ; ideal sp3 bonding
+ sp2, sp bonding
Known as a primary cause of
the residual stress in DLC structure
dependency of total energy of the system
on the bond angle & the electron density distribution
and its effects on the stress reduction behavior of DLC films

8. Tetrahedron bond modelC
109.5o Me
tetrahedral bonding of
carbon(or Me)-carbon
structure relaxation
total energy calculation
; reference state
DEC-C
DEMe-C
90o~
130o C
90o~
130o Me
Bond angle distortion
bond distance relaxation
total energy calculation

9. Calculation condition
Code; DMOL3
Exchange-correlation potential; GGA (PBE)
Atomic orbital; double-zeta polarization basis set
Cutoff radius of atomic orbitals; 9 Å
All electron calculation
Spin consideration

10. Total energy change by the bond angle distortion

11. Formation energy of Me-C tetrahedron
DEfM-C = (EtotM-C + EatomC) - (EtotC-C + EatomM) Me
DEfM-C Me

12. Isosurface of electron density; C-C-tetrahedron
0.5
1.5
1.0
90o C
1.5
1.0
0.5
Inset values are the electron density [Å-3] of the isosurface

13. Isosurface of electron density right before it is separatedV Ti Ni Si Mn W Cr Mo Co Fe C
109.5o

14. Isosurface of electron density right before it is separatedAg Ar Cd Au Al Zn Cu Pd C
109.5o

15. Electron density right before its isosurface is separated (res)
Weaker bonding
Lower angular dependency
of total energy
 stress reduction
Lower res
Lower shape anisotropy
of electron density

16. W-incorporated DLC films

17. Me-DLC films; Experimental
Hardness
Residual stress
Young’s modulus
By FCVA
P. Zhang, J. Vac. Sci. & Tech. A (2002).

18. Conclusion C Mn Au Al