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Haloalkanes as a Carbon Source for Growth of Si: and Amphoteric Doping of Si:Ge

IP.com Disclosure Number: IPCOM000122655D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 80K

Publishing Venue

IBM

Related People

Buchan, NI: AUTHOR [+4]

Abstract

Wide bandgap emitters or narrow bandgap bases are desirable features in Heterojunction Bipolar Transistors (HJBTs) (1). Current materials considered for these applications in silicon devices are silicon carbide (Si:C) for the wide bandgap emitter (2) and Si:Ge for the narrow bandgap base (3). These carbon-containing silicon materials may be grown using ultrahigh vacuum chemical vapor deposition (UHV/CVD). In this technique high uniformity of growth and doping is achieved due to low efficiencies of the growth and doping reactions, respectively. Current research in UHV/CVD uses methane (CH4) to grow the Si:C, but the efficiency of the carbon doping reaction is too low (4). Unpublished results using ethane (C2H6) to grow Si:C, or to reduce strain at the Si-Si:Ge interface, demonstrate poor crystallinity.

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Haloalkanes as a Carbon Source for Growth of Si: and Amphoteric Doping
of Si:Ge

      Wide bandgap emitters or narrow bandgap bases are
desirable features in Heterojunction Bipolar Transistors (HJBTs) (1).
Current materials considered for these applications in silicon
devices are silicon carbide (Si:C) for the wide bandgap emitter (2)
and Si:Ge for the narrow bandgap base (3).  These carbon-containing
silicon materials may be grown using ultrahigh vacuum chemical vapor
deposition (UHV/CVD). In this technique high uniformity of growth and
doping is achieved due to low efficiencies of the growth and doping
reactions, respectively.  Current research in UHV/CVD uses methane
(CH4) to grow the Si:C, but the efficiency of the carbon doping
reaction is too low (4).  Unpublished results using ethane (C2H6) to
grow Si:C, or to reduce strain at the Si-Si:Ge interface, demonstrate
poor crystallinity.  The use of molecular beam epitaxy (MBE) to grow
these materials may also be useful.  Improved growth and doping
characteristics in carbon-containing silicon materials by UHV/CVD and
MBE might result from using a class of compounds in which the
carbon-ligand bond strength is lower.  Compounds in which the
carbon-ligand bond is also readily-adjustable would allow an easy
path for process optimization.

      Potential sources of carbon with weakly bound ligands are
halomethanes (CHyX4-y, y=0-3). The doping efficiency is easily tuned
by both the substitution of halogens, X, for hydrogen in these
methane- based compounds, and by the choice of halogen. Carbon doping
with halomethanes in metalorganic CVD (5) and MBE (6) of GaAs has
been shown to be tunably increased to levels far exceeding that
possible with methane or ethane (7).  By analogy, the increased
carbon doping efficiency achieved with h...