Characteristics of sub-100-nm p+/n junctions fabricatedby plasma immersion ion implantation

Plasma immersion ion implantation (PIII) is an efficient method for fabricating high-quality p⁺/n diodes with junction depths below 100 nm. SiF₄ is implanted to create an amorphous Si layer to retard B channeling and diffusion, and then BF₃ is implanted. Ultrashallow p⁺/n junctions are formed by annealing at 1060 °C for 10 s. With the shallow implants, no extended defects are observed in device or peripheral areas due to rapid outdiffusion of fluorine. Diode electrical characteristics yield forward ideality factor of 1.05-1.06 and leakage current density below 2 nA/cm ² in the diode bulk. Minority-carrier lifetime below the junction is greater than 250 μs