Yasunori Ando

EL2, EL3, and EL6 defects in GaAs highly implanted with sulfur

Sulfur ions were implanted into a semi-insulating GaAs wafer at 50 keV at a dose of 1×1015 cm−2. The implanted GaAs wafer was annealed at temperatures of 650–1000 °C for 15 min. Deep levels were measured in regions with carrier concentrations lower than 3×1017 cm−3, after layers of various thicknesses were removed from the surface of the wafer. The dominant defects in samples annealed at temperatures lower than 850 °C were EL2 and EL6, while 1000 °C annealed samples exhibited isolated EL2 and EL3 defects. Isolated EL2 defects were observed in regions of carrier concentrations lower than 1×1017 cm−3, and EL3 defects were observed in regions of carrier concentrations higher than 2×1017 cm−3.

Increase of Beam Current Mass‐Separated by Long Gap Dipole Sector Magnet for S/D Process in FPD manufacturing

A mass analyzing ion implantation system (called Ion Doping iG4) was developed for FPD manufacturing. One of most important concept of iG4 is to transport a sheet ion beam maintaining its current density profile from the ion source to the target, which leads good mass resolution and simple control of the beam profile. The system has a bucket type ion source which provides a sheet ion beam whose longer dimension of the cross section is 800 mm the 4th generation FPD glass substrate generally sized 730mm × 920mm. The sheet ion beam is mass‐analyzed with a dipole sector magnet with a long pole gap. In order to enhance through‐put for Source Drain implantation processes, we modified the ion source to increase high beam currents and obtained 300μA/cm for Boron ion beams and 500μA/cm for Phosphorus ion beams. Better uniformity and higher mass resolution were achieved by optimizing shape of the analyzing magnet pole faces.

Hydrogenation of High-Concentration Arsenic-Doped Silicon Using Radio Frequency Hydrogen Plasma

n-type layers in silicon with high carrier concentrations have been formed by high-dose (1×1015–1×1016 cm-2) As-ion implantation and subsequently 950°C-annealing. The n-type layers containing many As clusters were exposed to radio-frequency hydrogen plasma for 30 min. While the hydrogenated samples had the same As-atom concentration profile as the as-annealed samples, the carrier concentration profiles approached the As atom concentration profile with increasing substrate temperature. The activation energy obtained from the Arrhenius plot of the carrier concentration agreed well with that of the diffusivity of H atoms in silicon. Thus, the increase in the carrier concentration is a result of H atoms reacting with As clusters.