분자동역학을 이용한 금속표면의 분자동역학을 이용한 금속표면의 Kinetic Kinetic Roughening Roughening 현상에 대한 재 증착 효과 연구현상에 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, Korea2. Division of Advanced Materials Science Engineering, Hanyang University, Seoul, Korea3. Department of Physics, Sook-Myung Women’s University, Seoul, Korea

2007 년 추계 금속재료학회 전산재료과학분과 심포지엄

Ion Bombardment (Sputtering)Ion Bombardment (Sputtering)

T.C. Kim et al., PRL 92, 246104 (2001).

Ion bombardmentIon bombardment

Sputter deposition

Morphological evolution of the sputtered surface

We focused on the structural evolution in Ion Bombardment

“Quantum dots” on GaSb, fabricated by normal-incidence 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.

Kinetic Roughening (Patterning)Kinetic Roughening (Patterning)

Theoretical ApproachTheoretical ApproachSigmund’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…)

Sputtering Process Erosion + Redeposition

Re-deposition EffectRe-deposition EffectIon

Sputtered atoms

Adatoms (or redeposited atoms)

Sputtering Process Erosion (conventional concept)

10 keV Ar ion impacts on Au(001)

Calculation ProcedureCalculation Procedure

Au & Pd(001)

0.5 keV

0, 30, 45, 60, 75°

Materials

Incident Angle(Ө)

Incident Energy

Φ = 0°

Ar+Ion

Force field EAM1) + ZBL2) 1) S.M. Foiles et al., PRB 33, 7983 (1986).

2) J.F. Ziegler et al., The Stopping and Range of Ions in Matter, Pergamon, New York, (1985).

Temperature: 300 K damping layer included

Sputter Yield & RedepositionSputter Yield & Redeposition

0 10 20 30 40 50 60 70 80 900

1

2

3

4

Sput

terin

g Yi

eld

(ato

ms/

ion)

Incident Angle (degrees)

Au Pd

0.5keV Ar

0 10 20 30 40 50 60 70 80 900

4

8

12

16

20

Red

epos

ition

Yie

ld (a

tom

s/io

n)Incident Angle (degrees)

Au Pd

0.5keV Ar

Sputter Yield vs. RedepositionSputter Yield vs. Redeposition

0 10 20 30 40 50 60 70 80 901.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

R

atio

Incident Angle (degrees)

Au Pd

Ratio = Yredeposition / YSputtering

Redeposition DistributionRedeposition Distribution

-60 -40 -20 0 20 40 60-60

-40

-20

0

20

40

60

0.5keV Au Normal

Y

0.5keV Au 30

-60 -40 -20 0 20 40 60-60

-40

-20

0

20

40

60

0.5keV Au 45

Y

X-60 -40 -20 0 20 40 60

Y

0.5keV Au 60

Au

Redeposition DistributionRedeposition DistributionPd

-60

-40

-20

0

20

40

60

0.5keV Pd Normal

Y

0.5keV Pd 30

-60 -40 -20 0 20 40 60

0.5keV Pd 60

X-60 -40 -20 0 20 40 60

-60

-40

-20

0

20

40

60

0.5keV Pd 45

Y

X

Summary & Future worksSummary & 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.

+ + αα