(1) Investigation of charge-up and ion reflection effects in SiO2
etching using a three-dimensional charge-up simulation

Sung Jin Kim (POSTECH, Korea)

A charge-up damage is one of plasma process induced damages and comes
from different motions of ions and electrons. We have performed a
three-dimensional charge-up simulation [1] to examine charge-up
effects. Kinetic results of particles obtained from 1D
particle-in-cell simulations [2] are used as input parameters of the
3D charge-up simulation. Charge-up potential and etching rates are
calculated according to ion energy distributions, aspect ratios of
trenches, and secondary electron emission coefficients. In ion
physical etching with etching rate less than 1 $\mu $m/min, since a
charge-up potential saturated time is shorter than a one-atomic layer
etched time, charge-up potential plays an important role in etching
profile evolution. Ion reflection coefficients calculated by trim code
and inequality of ion and electron fluxes on wafers are considered to
investigate ion reflection, which creates undesirable etching
profiles. *This work is supported by Tera-level nanodevices in Korea
Ministry of Science and Technology. 

[1] H.S. Park, S.J. Kim, J.K. Lee, IEEE Trans. Plasma Science, 31
(2003) 703 
[2] H.C. Kim, J.K. Lee, Phys. Rev. Lett., 93 (2004) 085003

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(2) Radially localized abnormal discharge

Gon Jun Kim (POSTECH, Korea)

Applying 100 MHz in the small electrode, 2 MHz in the large electrode,
by using several 2D PIC code, we obtain the radially localized density
profile. Initially the off-centered peak density profile is formed. As
time goes on, the peak density merges to the center. During merging,
it shows radially and axially nonlocalized plasma.