분자동역학을 이용한 금속표면의 Kinetic Roughening 현상에 대한 재 증착 효과 연구 Sang-Pil Kim 1,2, Kwang-Ryeol Lee 1, Jae-Sung Kim 3 and Yong-Chae Chung 2 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 2007 년 추계 금속재료학회 전산재료과학분과 심포지엄

Ion Bombardment (Sputtering) T.C. Kim et al., PRL 92, (2001). Ion 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)

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…)

Sputtering Process  Erosion + Redeposition Re-deposition Effect Ion Sputtered atoms Adatoms (or redeposited atoms) Sputtering Process  Erosion (conventional concept) 10 keV Ar ion impacts on Au(001)

Calculation Procedure Au & Pd(001) 0.5 keV 0, 30, 45, 60, 75 ° Materials Incident Angle (Ө) Incident Energy  Φ = 0 ° Ar + Ion  Force field  EAM 1) + ZBL 2) 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 & Redeposition

Sputter Yield vs. Redeposition

Redeposition Distribution Au

Redeposition Distribution Pd

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