Comparative Study of Self-Sputtering Effects of Different Boron-Based Low-Energy Doping Techniques

Angle-resolved X-ray photoelectron spectroscopy method was used to study self-sputtering effects of different p-type (boron-based) low-energy doping techniques, including conventional monoatomic ¹¹B beam-line ion implant, molecular beam-line ion implants, cluster B beam-line ion implant, and plasma doping (PLAD). It has been found that the self-sputtering effects of the beam-line implants correlate with the mass of ion species except for BF₂ implant. Cluster B implant shows severe self-sputtering effect and surface roughness due to its very heavy and very large cluster ions. BF₂ implant shows severe sputtering/etching effect but comparable roughness due to a combination of the physical sputtering and reactive ion etching. PLAD processes using B₂H₆ and BF₃ gas species have no sputtering effects but have deposition under certain process conditions.