Phosphorus diffusion and deactivation during SiGe oxidation

Journal Article · Fri Apr 07 00:00:00 EDT 2023 · Journal of Applied Physics

DOI:https://doi.org/10.1063/5.0145730· OSTI ID:1968108

Thornton, Chappel S. ^[1]; Shen, Xiao  ^[2]; Tuttle, Blair  ^[3]; Li, Xuebin ^[4]; Law, Mark E.  ^[5]; Pantelides, Sokrates T.  ^[6]; Wang, George T.  ^[7]; Jones, Kevin S.  ^[1]

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1. Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611, USA
2. Department of Physics and Materials Science, University of Memphis, Memphis, Tennessee 38152, USA
3. Department of Physics, The Pennsylvania State University-Behrend, Erie, Pennsylvania 16563, USA, Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, Tennessee 37235, USA
4. Applied Materials, Sunnyvale, California 94085, USA
5. Department of Electrical and Computer Engineering, University of Florida, Gainesville, Florida 32611, USA
6. Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, Tennessee 37235, USA, Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37212, USA
7. Advanced Electronic and Optoelectronic Materials Department, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA

Dopant profiles near the semiconductor–oxide interface are critical for microelectronic device performance. As the incorporation of Si _1−x Ge _x into transistors continues to increase, it is necessary to understand the behavior of dopants in Si _1−x Ge _x . In this paper, the diffusion and electrical activation of phosphorus within a strained, single-crystal Si _0.7 Ge _0.3 layer on Si during oxidation are reported. Both layers were uniformly doped, in situ, with an average phosphorus concentration of 4 × 10 ¹⁹  atoms/cm ³ . After high-temperature oxidation, secondary ion mass spectrometry measurements revealed that the bulk of the phosphorus diffuses out of only the SiGe layer and segregates at the oxidizing SiGe–SiO ₂ interface. Hall effect measurements corroborate the observed phosphorus loss and show that the phosphorus diffusing to the oxidizing interface is electrically inactive. Through density functional theory (DFT) calculations, it is shown that phosphorus interstitials prefer sites near the SiGe–SiO ₂ interface. Finally, based on a combination of experimental data and DFT calculations, we propose that the phosphorus atoms are displaced from their lattice sites by Ge interstitials that are generated during SiGe oxidation. The phosphorus atoms then migrate toward the SiGe–SiO ₂ interface through a novel mechanism of hopping between Ge sites as P–Ge split interstitials. Once they reach the interface, they are electrically inactive, potentially in the form of interstitial clusters or as part of the reconstructed interface or oxide.

• Sponsoring Organization: USDOE
• OSTI ID: 1968108
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Vol. 133 Journal Issue: 13; ISSN 0021-8979
• Publisher: American Institute of Physics
• Country of Publication: United States
• Language: English