Comparison of trenches treated in PIII-systems

A total of four different implantations into trenches were performed in two different plasma immersion ion implantation (PIII) systems to compare the dose inhomogeneities observed in each experiment. The following experiments were performed: (i) Ne into Si; (ii) O into Ti; (iii) N into Al; and (iv) Ar into Ta2O5. These were chosen to encompass low dose implantation, phase formation and etching processes. In every system a high dose region along the centre of the trench bottom, separated from two low dose regions at the outside of the bottom was found. Additionally, a complex shaped structure along the sidewall connects this part with the upper corners of the trenches. Several different mechanisms are discussed, however, the only consistent explanation is that ions entering the trench from the side lead to these effects, which are not observed in two-dimensional simulations. For longer trenches this effect is weaker or no longer observable.