Evolution of arsenic in high fluence plasma immersion ion implanted silicon: Behavior of the as-implanted surface

• Published in: Applied surface science Vol. 355; no. C; pp. 792 - 799
• Main Authors: Vishwanath, V., Demenev, E., Giubertoni, D., Vanzetti, L., Koh, A.L., Steinhauser, G., Pepponi, G., Bersani, M., Meirer, F., Foad, M.A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.11.2015; Elsevier
• Subjects: Arsenic; Arsenic implantation; As-implanted silicon; Deposition; Enhanced oxidation; Exposure; Fluence; Immersion; Low energy; Plasma immersion ion implantation (PIII); Silicon; Silicon oxides; Arsenic implantation; Plasma immersion ion implantation (PIII); Arsenic; As-implanted silicon; Enhanced oxidation
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2015.07.068

•Samples prepared by high fluence, low-energy PIII of AsH3+ on Si(100) were studied.•PIII is of high technological interest for ultra-shallow doping and activation.•We used a multi-technique approach to study the As-implanted surface.•We show that PIII presents a new set of problems that needs to be tackled.•The presented study goes toward understanding the root mechanisms involved. High fluence (>1015ions/cm2) low-energy (<2keV) plasma immersion ion implantation (PIII) of AsH3+ on (100) silicon was investigated, with the focus on stability and retention of the dopant. At this dose, a thin (∼3nm) amorphous layer forms at the surface, which contains about 45% arsenic (As) in a silicon and oxygen matrix. The presence of silicon indicates that the layer is not only a result of deposition, but predominantly ion mixing. High fluence PIII introduces high concentration of arsenic, modifying the stopping power for incoming ions resulting in an increased deposition. When exposed to atmosphere, the arsenic rich layer spontaneously evolves forming arsenolite As2O3 micro-crystals at the surface. The micro-crystal formation was monitored over several months and exhibits typical crystal growth kinetics. At the same time, a continuous growth of native silicon oxide rich in arsenic was observed on the exposed surface, suggesting the presence of oxidation enhancing factors linked to the high arsenic concentration at the surface.