Lateral implantation homogeneity of wedge-shaped samples treated by plasma immersion ion implantation

Plasma immersion ion implantation (PIII) is a rapidly developing technique for ion implantation in metallurgical and semiconductor applications. In contrast to conventional beam-line ion implantation, the treatment of three-dimensional samples does not require complicated workpiece and ion beam manipulation. However, recent results have shown that, in addition to the shape of the workpiece, treatment homogeneity is strongly dependent on process parameters such as ion density and gas pressure. Knowledge of homogeneity is of great importance for the further development of PIII. In the present paper, homogeneity measurements of a model system are discussed. Wedge-shaped silicon specimens with different angles (30 degrees to 90 degrees) were treated by plasma immersion ion implantation with argon ions with 45 kV high-voltage pulses. The samples were analyzed for lateral implantation concentration by Rutherford backscattering measurements. The implanted concentration, the projected range and their gradient are a strong function of the edge angle. The results show that for acute angles (30 degrees), gradients in implantation concentration up to a factor five develop. (C) 1997 Elsevier Science S.A.