Feasibility study of plasma doping using B<inf>2</inf>H<inf>6</inf> and PH<inf>3</inf> for shallow junction

Abstract

Several features of plasma doping (PD) are discussed. First, the performance of PD is compared to conventional ion implantation for characteristics such as dose uniformity, repeatability, particles, metal contamination, photo-resist (PR) removal and charging performance. The numerical results are as follows:(1) doping uniformity of boron and phosphorous is about 1.5% and 1%, respectively, within a 300-mm wafer and using practical throughput. (2) Particles is more than three per wafer at 0.15μm or larger during a 2,000 wafer test run. (3) Metal contamination is below 1E10/cm 2 for all of the major metals including aluminum.Secondly, we discovered a means to eliminate dimples normally created during anneal of He-based PD.Finally, we found a mechanism whereby helium atoms physically drive boron and phosphorous atoms more deeply into the silicon substrate. The mechanism is quite different from conventional ion implantation and enhances abruptness of dopant depth profiles. Thus, we concluded that this type of PD system is a leading candidate for doping at the 22nm node and beyond as well as for 450-mm wafer fabrication.