Plasma immersion ion implantation is a new technique pertaining to ion implantation. Different from the case of exterior surface treatment

plasma immersion ion implantation of interior surface possesses dimension effects. Consequently it is a challenge to implant the inner wall of a cylindrical bore due to this finite dimension. The ion energy cannot be linearly changed with applied voltage and there exists a saturation value due to overlap effect of plasma sheath. The plasma in the bore may rapidly be depleted

which is attributed to finite plasma volume and plasma-sheath conflowing effect. For instance the plasma depletion time is about 0.55 μs when a bore with a diameter of 20cm is treated under conditions of applied voltage of 30kV and plasma density of 2×10 15 ions/cm 3. Interior plasma-source hardware may be an effective solution.