Transient diffusion of ion-implanted B in Si: Dose, time, and matrix dependence of atomic and electrical profiles

Abstract

The time evolution of B diffusion and electrical activation after ion implantation and annealing at 800 and 900 °C is studied using secondary-ion mass spectrometry and spreading-resistance profiling. The time evolution at 800 °C is observed in both crystalline and post-amorphized samples. Amorphized samples show near-normal concentration enhanced diffusion. Crystalline samples show anomalous transient diffusion, with a rapidly diffusing low-concentration region and a static peak region above a critical concentration Cenh=3.5×1018 cm−3. The peak region above Cenh is shown to be electrically inactive. The static, inactive B is released over a period of many hours, compared with the transient diffusion enhancement which relaxes to near-normal within 30 min. The time evolution of B diffusion at 900 °C is observed as a function of implantation dose. A critical concentration for transient diffusion, Cenh=8×1018 cm−2, independent of dose, is observed at this temperature. The transient diffusion enhancement in the diffusing part of the B profile increases with dose, up to a dose of ∼5×1014 cm−3, and saturates at higher doses. A comparison with published data shows that Cenh∼ni within a factor 2 over the temperature range 550–900 °C. We interpret our observations in terms of a nonequilibrium point-defect model of diffusion and intermediate defect formation.

Below-band-gap electroluminescence related to doping spikes in boron-implanted siliconpndiodes

“…Taking into account the unavoidable boron clustering during the ramp up of the heating above 700°C in the very early stage of furnace annealing of our samples, the value of C enh is in the range of 1 -2 ϫ 10 19 cm −3 at a temperature of 900°C and then increases close to the boron solubility limit at 1050°C. 15,34 This is the same concentration as the threshold boron concentration of 1.0ϫ 10 19 cm −3 for the observation of EL from the bound exciton peaks P I TO and P II TO in our boron implanted diodes [ Fig. 3(b)].…”

First-principles calculations of interstitial boron in silicon

“…Zhu et al 9 calculated the energy barriers and binding energies for the kickout process for the neutral charge state. They also calculated binding energies for a complex containing two B atoms, which may be involved in the immobile 10 and electrically inactive 11 B regions observed in TED experiments at higher doses of B. Additional calculations by Zhu 12 were reported for the positive and negative charge states of the ground-state configuration of B i and for some interstitial positions.…”

Enhancement of phosphorus activation in vacancy engineered thin silicon-on-insulator substrates

“…Source/Drain Extensions (SDE) are vital components within the device architecture, helping reduce detrimental phenomena such as short channel effects. However, the ability to produce such Ultra-Shallow Junctions (USJs) to the required specification in terms of sheet resistance (R s ) and junction depth (X j ) with a traditional implantation and anneal process, is significantly reduced due to dopant-defect interactions which result in anomalous diffusion [2] and clustering behavior [3] that increases the junction depth and sheet resistance, respectively.…”