Time-resolved evolution of collisional transient sheath in plasma source ion implantation

Abstract

In this work, an analytical model for the time-resolved dynamics of the collisional transient sheath in the plasma source ion implantation (PSII) process is developed. The presented model can forecast the temporal dependence of the implanted ion flux and sheath width in the collisional transient sheath. During the PSII process, the effects of some physical parameters such as applied voltage and gas pressure on the pattern of sheath growth are discussed. It is found that the ion flux can get higher values by increasing the gas pressure during the matrix sheath while the dynamics of ions in the expanding sheath are restricted to the collisionality condition, and ion flux is reduced impressively. Moreover, these results are demonstrated that the increase of the applied voltage causes the high rate of sheath expansion and electric field and then ion flux. The final value of the ion velocity in the expanded sheath tends to the ion Bohm velocity.