AVS 63rd International Symposium & Exhibition
    Plasma Science and Technology Thursday Sessions
       Session PS1-ThM

Paper PS1-ThM3
Three Dimensional Monte Carlo Simulation of Surface Charging on a Contact Hole during Pulsed Plasma Etching

Thursday, November 10, 2016, 8:40 am, Room 104C

Session: Modeling of Plasmas and Plasma-Surface Interactions
Presenter: Yugo Osano, Samsung R&D Institute Japan
Authors: Y. Osano, Samsung R&D Institute Japan
Y. Higuchi, Samsung R&D Institute Japan
Y. Nishizawa, Samsung R&D Institute Japan
M.H. Cha, Samsung Electronics, Republic of Korea
H. Kubotera, Samsung R&D Institute Japan
K.H. Lee, Samsung Electronics, Republic of Korea
Correspondent: Click to Email
Three-dimensional (3D) simulation model has been developed to analyze the surface charging on a contact hole during plasma etching process, with emphasis placed on surface charging mitigated by employing pulse-time-modulated (TM) plasma. Surface charging and its influence on the trajectories of ions and electron are investigated with Monte Carlo (MC) procedure in level-set represented 3D-polygon geometries under uniform square lattice. The distribution of steady state surface charging is achieved by recursive calculation of charge accumulation from the ion/electron transport under the self-consistent electric field, and electric field is calculated by solving Poisson’s equation for the accumulated charge. For the plasma description, time averaged ion/electron flux is used for continuous wave (CW) plasma, and the TM plasma is modeled by alternating two different sets of fluxes and incident energies of ions and electrons which corresponds to pulse-on and pulse-off states. The incident energy of electrons is set to be significantly lower in pulse-off state than in pulse-on state, to simulate decreased electron temperature during pulse-off. Calculations are performed for a silicon oxide contact hole with mask, where the surface geometry is shaped in an inversed truncated circular cone of aspect ratio ~10. Numerical results reproduced accumulation of surface charging showing distinct difference between CW and TM plasma. In a CW condition, surface charging is simply accumulated until the fluxes of electrons and ions become locally equivalent owing to their deflection by local electric field. Meanwhile, the distribution of surface charging varies at all time in a TM condition and exhibits significant contrast to CW (including sign of charging) upon TM plasma conditions such as duty ratio, frequency, etc. In accordance with charging distribution, the potential distribution is also significantly different between CW and TM plasma. The potential increases deeper in the contact hole with its maximum shown near at the bottom of the hole in a CW condition, whereas it shows fluctuating distribution in a TM condition.