Diffusion of phosphorus and boron from Atomic Layer Deposition oxides into silicon

Oxides containing group III or group V elements (B2O3/Sb2O5 and P2O5/Sb2O5) were grown by plasma-assisted atomic layer deposition (ALD) onto single-crystalline silicon and serve as dopant sources for conformal and shallow doping. Transport phenomena in ALD-oxide-Si structures during rapid thermal annealing (RTA) were investigated subsequently by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS). The XPS and TEM analyses of the annealed ALD-oxide-Si structures demonstrate that the ALD oxide converts to a silicon oxide and partially evaporates during annealing. In addition, dopant-containing, spherical, partially crystalline particles were found to form in the oxide, and Si-P precipitates at the oxide/Si interface. In the silicon substrate, phosphorus and boron were observed to diffuse in at high concentrations, exceeding their solid solubility limits by roughly one order of magnitude. Experimental doping profiles of phosphorus and boron in silicon are compared with simulation results considering a slight injection of self-interstitials and dynamical defect clustering.