Measured and Calculated Dose Distribution for 3-D Plasma Immersion Ion Implantation

Nitrogen was implanted into four cylinders (height 37
mm and diameter 4, 6, 8, and 12 mm) covered with aluminium foil using plasma
immersion ion implantation at 30 kV. The homogeneity of the implantation,
i.e. the spatial variation of the implanted dose, was determined for selected
points on the top and the side walls of the cylinders with sputter depth
profiling using Auger electron spectroscopy. Calculations approximating
the dynamic sheath evolution with discrete sheath positions were performed
to obtain the variation of the implanted dose and angle of incidence. Good
agreement is found between the calculations and the experimental data.
The ion dose exhibits a maximum on the top and decreases on the side walls.
A second maximum is formed on the wall of the cylinder. The total dose
variation is of the order of 50 %.