ECI Digital Archives

Title

Langmuir-type mechanism for in-situ doping in CVD Silicon and Germanium Epitaxial Growth

Authors

Junichi Murota, Tohoku University, SendaiFollow

Conference Dates

May 19-23, 2019

Abstract

High performance Si-based devices require atomically ordered interface of heterostructures and doping profiles as well as strain engineering due to the introduction of Ge into Si. The fabrication of atomic-level steep doping profiles needs the suppression of dopant segregation during epitaxial growth [1]. In this work, in-site doping of P and B in CVD Si, Ge and Si_1-xGe_x epitaxial growth using SiH₄-GeH₄-dopant (PH₃ and B₂H₆)-H₂-He gas mixtures [1, – 7] is reviewed based on the Langmuir-type surface adsorption and reaction scheme.

Anomalous heavy doping of P is explained, assuming that GeH₄ adsorbs/reacts partially at the sites where PH₃ molecules have been adsorbed on (100) surface, although the sites become inactive for both the SiH₄ and GeH₄ adsorption/reactions on the surface [2]. Based on the experimental results that P atoms of 3, 2, 1 atomic layer is formed self-limitedly on the Si-Si, Si-Ge, Ge-Ge sites by PH₃ at the epitaxial growth temperature [2 – 4], the adsorption/reaction site density for PH₃ at each site is assumed. The adsorption and desorption rate constants of PH₃ and the incorporation rate constant of P atoms into the epitaxial layer from the adsorbed PH₃ molecules at each site are obtained numerically by fitting the experimental data for low PH₃ partial pressure region to the modified Langmuir-type mechanism. The segregation coefficient between surface coverage of PH₃ molecules and the concentration of P incorporated into the grown film at each site and growth rate constant of GeH₄ on adsorbed PH₃ molecules are also obtained numerically from the data for high PH₃ partial pressure region. The adsorption rate constant of SiH₄ and GeH₄ and reaction rate constant of SiH₄ at each site in refs. 2 are used.

Anomalous heavy doping of B is explained, assuming that SiH₄, GeH₄ and B₂H₆ adsorb/react partially at the sites where B₂H₆ molecules have been adsorbed on (100) surface [5]. It was confirmed that B atoms deposit continuously without self-limitation at the Si_1-xGe_x epitaxial growth temperature [6] and B atoms enhances the SiH₄ adsorption/reaction [7]. Therefore, it is also assumed that there is no segregation of B on the grown surface.

Please click Additional Files below to see the full abstract.

Recommended Citation

Junichi Murota, "Langmuir-type mechanism for in-situ doping in CVD Silicon and Germanium Epitaxial Growth" in "Semiconductor Technology for Ultra Large Scale Integrated Circuits and Thin Film Transistors VII (ULSIC VS TFT 7)", Yue Kuo, Texas A&M University, USA Junichi Murota, Tohoku University, Japan Yukiharu Uraoka, Nara Advanced Institute of Science and Technology, Japan Yasuhiro Fukunaka, Kyoto University, Japan Eds, ECI Symposium Series, (2019). https://dc.engconfintl.org/ulsic_tft_vii/37