Comparison of Microstructure and Crystal Structure of Polycrystalline Silicon Exhibiting Varied Textures Fabricated by Microwave and Very High Frequency Plasma Enhanced Chemical Vapor Deposition and Their Transport Properties
Micro- and crystal structures of polycrystalline silicon ( poly -Si) films fabricated by low temperature (≤360°C) plasma enhanced chemical vapor deposition (PECVD) were examined. Crystal orientation could be controlled by varying the source gas ratio SiF 4 /H 2 . (220) oriented films were obtained a...
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Veröffentlicht in: | Japanese Journal of Applied Physics 1999, Vol.38 (10R), p.5750 |
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Hauptverfasser: | , , , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Micro- and crystal structures of polycrystalline silicon
(
poly
-Si) films fabricated by low temperature
(≤360°C) plasma enhanced chemical vapor
deposition (PECVD) were examined. Crystal orientation could be
controlled by varying the source gas ratio SiF
4
/H
2
. (220)
oriented films were obtained at low gas flow rate ratios while (400)
preferentially oriented films were obtained at higher
SiF
4
/H
2
ratios either by a remote-type microwave PECVD or a
capacitive coupled parallel electrode very high frequency (VHF)
PECVD. It was found that micro- and crystal structures were a strong
function of orientation; that is, the crystal lattice in the (220)
oriented film was under tensile strain and the crystalline grain had
strong anisotropy of grain size. In contrast, the crystal lattice in
the (400) oriented film was under compressive strain and evident
anisotropy in the grain size could not be found. Furthermore, it was
confirmed that the deposition of SiH
n
and/or
SiH
n
F
m
and etching by fluorinated species and their
competition played an important role in the selective
growth. Fluorine-related species were also effective in growing large
crystalline grains. Hall mobility of electron for (400) oriented films
showed a monotonic increase with carrier density and achieved a large
mobility of ∼10 cm
2
/Vs. |
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ISSN: | 0021-4922 1347-4065 |
DOI: | 10.1143/JJAP.38.5750 |