Effect of hydrogen implantation on low-temperature activation of boron in silicon

Abstract

Understanding the behavior of dopant activation at low temperatures is necessary for three-dimensional integration of transistors. In this work, the impact of hydrogen coimplantation on boron activation was investigated at implantation doses below the amorphization threshold. The carrier depletion effect due to substrate doping was simulated to accurately characterize the initial activation behavior of boron. At temperatures higher than 400 °C, the boron activation level decreased as the hydrogen dose increased. The deactivation caused by hydrogen diminished after extended annealing at 500 °C. This indicated the passivation of boron by hydrogen. However, the boron activation in the sample implanted with hydrogen at a dose of 1 × 1015 cm−2 was first degraded and then enhanced during annealing at 300 °C. The time-dependent activation behavior suggested the elimination of isolated defects via reactions associated with hydrogen migration.