Download Ion Bombardment

2007년 추계 금속재료학회 전산재료과학분과 심포지엄
분자동역학을 이용한 금속표면의 Kinetic
Roughening 현상에 대한 재 증착 효과 연구
Sang-Pil Kim1,2, Kwang-Ryeol Lee1, Jae-Sung Kim3 and Yong-Chae Chung2
1. Computational Science Center, KIST, Seoul, Korea
2. Division of Advanced Materials Science Engineering, Hanyang University, Seoul, Korea
3. Department of Physics, Sook-Myung Women’s University, Seoul, Korea
Ion Bombardment (Sputtering)
Sputter deposition
Ion bombardment
Morphological evolution
of the sputtered surface
 We focused on the structural evolution in Ion Bombardment
T.C. Kim et al., PRL 92, 246104 (2001).
Kinetic Roughening (Patterning)
 “Quantum dots” on GaSb, fabricated by normalincidence sputter patterning using 420 eV Ar+.
Dots sizes ~ 15 nm.
Facsko et al., SCIENCE (1999)
Under some conditions of uniform ion irradiation,
spontaneously-arising sputter pattern
topography arises that takes the form of 1-D
ripple or 2-D arrays of dots.
Theoretical Approach
Sigmund’s theory
•
Limitation in linear theory
 Agreement: ripple formation/ orientation
 Disagreement: wavelength coarsening, multi-ion beam sputtering
•
Toward improvement
 Nonlinear terms considered
 New terms included to the equation
(ex. shadowing effect, surface anisotropy, re-deposition effect…)
Re-deposition Effect
Ion
Sputtering Process
 Erosion (conventional
concept)
+ Redeposition
Sputtered atoms
Adatoms (or redeposited atoms)
10 keV Ar ion impacts on Au(001)
Calculation Procedure
Ion
Ar+
Materials
Au & Pd(001)
Incident Energy
0.5 keV
Incident Angle
(Ө)
0, 30, 45, 60, 75°
 Φ = 0°
 Temperature: 300 K
 damping layer included
 Force field
 EAM1) + ZBL2)
1)
2)
S.M. Foiles et al., PRB 33, 7983 (1986).
J.F. Ziegler et al., The Stopping and Range of
Ions in Matter, Pergamon, New York, (1985).
Sputter Yield & Redeposition
20
Redeposition Yield (atoms/ion)
Sputtering Yield (atoms/ion)
4
3
2
0.5keV Ar
1
Au
Pd
0
16
12
8
0.5keV Ar
4
Au
Pd
0
0
10
20
30
40
50
60
Incident Angle (degrees)
70
80
90
0
10
20
30
40
50
60
Incident Angle (degrees)
70
80
90
Sputter Yield vs. Redeposition
6.0
5.5
Ratio = Yredeposition / YSputtering
5.0
Au
Pd
4.5
Ratio
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0
10
20
30
40
50
60
Incident Angle (degrees)
70
80
90
Redeposition Distribution
60
Au
0.5keV Au 30
0.5keV Au Normal
40
Y
20
0
-20
-40
-60
60
-60
-40
-20
0
20
40
60
40
Y
20
0
-20
-40
0.5keV Au 60
0.5keV Au 45
-60
-60
-40
-20
0
X
20
40
-60
60
-40
-20
0
Y
20
40
60
Redeposition Distribution
60
Pd
0.5keV Pd Normal
0.5keV Pd 30
0.5keV Pd 45
0.5keV Pd 60
40
Y
20
0
-20
-40
-60
60
40
Y
20
0
-20
-40
-60
-60
-40
-20
0
X
20
40
-60
60
-40
-20
0
X
20
40
60
Summary & Future works
• The effect of redeposition clearly shown on
Au, Pd surface.
• From MD calculation, we could obtain
quantitative parameters of redeposition effect
(ratio, distribution).
• Based on MD calculation, we could improve
kinetic roughening equation.
+α