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Process to Inhibit Recrystallization of N-mc-si:h During Rapid Thermal Annealing

IP.com Disclosure Number: IPCOM000102690D
Original Publication Date: 1990-Dec-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 3 page(s) / 120K

Publishing Venue

IBM

Related People

Jeng, SJ: AUTHOR [+6]

Abstract

Disclosed is a process which has been shown to inhibit the crystallization of in-situ doped hydrogenated microcrystalline silicon (n-mc-Si:H) during rapid thermal annealing (RTA) at temperatures of up to 900oC for duration of 30 seconds.

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Process to Inhibit Recrystallization of N-mc-si:h During Rapid Thermal Annealing

       Disclosed is a process which has been shown to inhibit
the crystallization of in-situ doped hydrogenated microcrystalline
silicon (n-mc-Si:H) during rapid thermal annealing (RTA) at
temperatures of up to 900oC for duration of 30 seconds.

      In-situ doped n-mc-Si:H consists of a mixed phase
microstructure containing both amorphous-Si and small crystalline-Si
grains with diameter & 40 Angstroms.  As deposited, the wide band-gap
(> 1.2 eV) and high conductivity of n-mc-Si:H make it an attractive
material for use as an emitter in a heterojunction bipolar transistor
(HBT).  But, the structural stability of this material degrades when
subjected to high temperature (>650oC) heat cycles, making this
material incompatible with current device processing.

      Films of in-situ phosphorus-doped mc-Si:H were deposited by
plasma-enhanced chemical vapor deposition (PECVD) on Si(100)
substrates from a reactive gas mixture containing PH3/SiH4/H2 .  The
Si substrates were cleaned. The substrates were loaded in a reaction
chamber which was pumped down to 10-6 Torr.  The n-mc-Si:H film was
deposited.  A deposition rate of 70 Anstroms/sec. was obtained, and a
4-minute deposition was used to produce a 280-Angstrom-thick film for
the annealing experiments described below.

      Other techniques, such as ECR-CVD, Photo-CVD, sputtering, etc.,
can also be used for the preparation of this material.  Similar
results are expected to be obtained for the films prepared by these
alternative techniques, as well as films deposited by PECVD at
different substrate temperatures, reactive gas pressures, RF power
densities, and PH3/SiH4/H2 dilutions.

      Cross-sectional lattice image transmission electron microscopy
(TEM) confirmed that the as-deposi...