Diffusion of Phosphorus and Boron from Atomic Layer Deposition Oxides into Silicon

• Published in: Physica status solidi. A, Applications and materials science Applications and materials science, 2019-09, Vol.216 (17), p.n/a
• Main Authors: Beljakowa, Svetlana, Pichler, Peter, Kalkofen, Bodo, Hübner, René
• Format: Article
• Language: English
• Subjects: Annealing; Antimony oxides; atomic layer deposition; Atomic layer epitaxy; Boron; Boron oxides; Clustering; cross-sectional transmission electron microscopy; Crystal structure; Crystallinity; Diffusion layers; dopant clusters; dopant diffusion; dopant-containing oxides; Dopants; Doping; Interstitials; Ions; Phosphorus; Phosphorus pentoxide; Photoelectrons; Precipitates; Secondary ion mass spectrometry; silicon doping; Silicon oxides; Silicon substrates; Solid solubility; Transmission electron microscopy; Transport phenomena; X ray photoelectron spectroscopy
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.201900306

Oxides containing group III or group V elements (B2O3/Sb2O5 and P2O5/Sb2O5) are grown by plasma‐assisted atomic layer deposition (ALD) on 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) are 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, and partially crystalline particles form in the oxide, and Si‐P precipitates at the oxide–Si interface. After diffusion annealing at 1000 °C, the SIMS analyses reveal phosphorus and boron concentration profiles in the silicon substrate with maximum 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. Transmission electron microscopy (TEM) investigations show that dopant‐oxide stacks such as P2O5/Sb2O5 and B2O3/Sb2O5 grown by atomic layer deposition (ALD) on silicon transfer during annealing to silicon oxide with embedded spherical, partially crystalline particles. Dopant diffusion from these layers leads to shallow profiles with high phosphorus (>1 × 1020 cm−3) and boron (>1 × 1021 cm−3) concentrations in silicon. A numerical analysis of the diffusion process is provided.