Journal of Crystal Growth, Vol.445, 65-72, 2016
Very low temperature epitaxy of Ge and Ge rich SiGe alloys with Ge2H6 in a Reduced Pressure - Chemical Vapour Deposition tool
We have studied the very low temperature epitaxy of pure Ge and of Ge-rich SiGe alloys in a 200 mm industrial reduced pressure chemical vapour deposition tool. We have, first of all, benchmarked germane (GeH4) and digermane (Ge2H6) for the growth of pure Ge. Used Ge2H6 instead of GeH4 enabled us to dramatically increase the Ge growth rate at temperatures 425 degrees C and lower (5.6 nm min(-1) compared to 0.14 nm min(-1) at 350 degrees C with a Ge2H6 mass-flow one fourth that of GeH4). We have also evaluated at 400 degrees C, 100 Torr, the impact of the GeH4 or Ge2H6 mass-flow on the Ge growth rate. For a given Ge atomic flow, the higher surface reactivity of digermane yielded roughly five times higher growth rates than with germane. We have then combined digermane with disilane (Si2H6) or dichlorosilane (SiH2Cl2) in order to study the GeSi growth kinetics at 475 degrees C, 100 Torr. While the SiH2Cl2 mass-flow did not have any clear influence on the GeSi growth rate (with a 14 nm min(-1) mean value, then), a Si2H6 mass-flow increase resulted in a slight GeSi growth rate increase (from 11 nm min(-1) up to 14 nm min(-1)). Significantly higher Ge concentrations were otherwise accessed with dichlorosilane than with disilane, in the 77-82% range compared to the 39-53% range, respectively. (C) 2016 Elsevier B.V. All rights reserved.
Keywords:Growth models;High resolution X-ray diffraction;Atomic force microscopy;Chemical vapour deposition processes;Semiconducting germanium;Semiconducting silicon compounds