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Time-resolved Cavity Ringdown Spectroscopy as a Monitoring Technique of Nanoparticles in Pulsed VHF Plasmas

Published online by Cambridge University Press:  01 February 2011

Takehiko Nagai ,
Arno H. M. Smets  and
Michio Kondo
Takehiko Nagai
Affiliation:
[email protected], National Institute of Advanced Industrial Science and Technology (AIST), Research Center for Photovoltaics, Central 2, 1-1-1 Umezono, Tsukuba, 305-8568, Japan, +81-29-861-3449, +81-29-861-3367
Arno H. M. Smets
Affiliation:
[email protected], National Institute of Advanced Industrial Science and Technology (AIST), Research Center for Photovoltaics, Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
Michio Kondo
Affiliation:
[email protected], National Institute of Advanced Industrial Science and Technology (AIST), Research Center for Photovoltaics, Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
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Abstract

Time-resolved cavity ringdown (τ-CRD) spectroscopy has been applied to monitor the sylil (SiH3) radicals and nano-particles in pulsed very high frequency (VHF) silane (SiH4)/hydrogen (H2) plasmas under microcrystalline silicon (μc-Si:H) deposition conditions. After the plasma ignition, a small constant cavity loss (~100 ppm) on timescales smaller than ~1 s has been observed, whereas on time scales larger than ~1 s after plasma ignition, an additional cavity loss is observed. By variation of the wavelength of the CRD laser pulse, we demonstrate that the cavity loss on time scales smaller than ~1 s reflects the SiH3 absorption. On time scales larger than ~1 s, the additional cavity loss corresponds to the loss of light due to mainly scattering at the nano-particles. Under the conditions studied, the light scattering at nano-particles can be described by Rayleigh scattering during its initial growth. After ~ 2.5 s, the cavity loss reflects the transition of the scattering mechanism from dominant Rayleigh to dominant Mie-scattering. These results are discussed in terms of nano-particles growing in time and further confirmed by additional scanning electron microscopy analyses on the nano-particles created in the plasma pulse.

Keywords

absorptionamorphousplasma-enhanced CVD (PECVD) (chemical reaction)
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 989: Symposium A – Amorphous and Polycrystalline Thin-Film Silicon Science and Technology-2007 , 2007 , 0989-A25-02
Copyright
Copyright © Materials Research Society 2007

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