Computer simulations of plasma immersion ion implantation of a patterned surface

Using a two-dimensional implementation of a hybrid Particle In Cell/Monte Carlo (PIC/MC) algorithm, the transient effects during plasma immersion ion implantation (PIII) of a patterend surface have been investigated. For the surface a periodic layout has been chosen, consisting of edges of width 2 mm and height 5 mm and trenches of depth 5 mm and alternating width 1 mm and 10 mm. An Ar plasma of neutral gas density nneutral = 2.57 x 1013 cm-3 has been simulated. The plasma density was chosen to be roughly nplasma = 2 x 1010 cm-3. The electron temperature was kTe = 8 eV, and the ion temperature 300 K throughout the simulation. As initial condition for the PIII simulation a fully established floating potential sheath with the target biased to -40 V compared to the plasma bulk has been used for the first time. Therefore the plasma density was nonhomogeneous and the ions drifted towards the target with a velocity of the order of the Bohm velocity uB = 4400 m/s.

By switching the target potential suddenly from value of the floating potential to the negative high voltage -1000 V at time t = 0, the electrons are repelled from and the ions are attracted to the target surface. The following movies show the temporal evolution of the ion and electron density ni and ne, of the electrical potential and of the electrical field close to the patterend surface of the target. Furthermore the distribution of the ion current density ji, the ion dose and the angle of impingment on the target surface developing in time are shown.

Movies (showing temporal evolution during 2 µs) of:

  1. ion density ni
  2. ion density ni in the vicinity of the target only
  3. electron density ne
  4. electrical potential
  5. electrical field
  6. ion current density ji on the target surface
  7. ion dose on the target surface (during 10 µs)
  8. ion angle of impingment on the target surface

June 17 2002