Effect of argon on the structure of hydrogenated nanocrystalline silicon deposited from tetrachlorosilane/hydrogen/argon plasma

Abstract

Hydrogenated nanocrystalline silicon films (nc‐Si:H) have been deposited by the decomposition of tetrachlorosilane (SiCl4) diluted with hydrogen (H2) and argon (Ar) by a plasma‐enhanced chemical vapor deposition (PECVD) method. Basing on the structural characterization of nc‐Si:H, we have found that Ar affects the growth of films deposited at two substrate temperatures (Ts = 250 and 120 °C) in different ways. At Ts = 250 °C, the Ar gas deteriorates the crystallinity of nc‐Si:H, whereas, at Ts = 120 °C, the crystallization of nc‐Si:H films is promoted with increasing argon flow rate (Hf) from 10 to 30 sccm; however, the extremely high Ar dilution adversely affects the ordered structure of films. Meanwhile, the hydrogen concentration in the films is also controlled by Hf. Finally, the effects of Ar in the SiCl4/H2/Ar system have been discussed in related to the equilibrium of atomic hydrogen and ionized argon.

High rate deposition of nanocrystalline silicon by thermal plasma enhanced CVD

“…The measured lm thicknesses and the calculated deposition rates are listed in Table 1. The maximum deposition rates using SiH 4 /H 2 and SiCl 4 /H 2 were reported as 1.57 nm s À1 , 12 and 0.17 nm s À1 , 18 respectively. The deposition rate under our operating conditions is in the range of 2.11-9.78 nm s À1 , which is much higher than the deposition rate reported.…”

“…This can be attributed to the much higher plasma power density and higher precursor input rate than the ones in the literature. 12,18 In the SiCl 4 -H 2 deposition system, the formation of Cl related radicals SiCl x (x ¼ 1, 2, 3) in gas phase is known to be the prominent feature of the reaction. By increasing plasma power, the generation of electrons and ions is intensied and the energy level of the electrons and ions can be improved, which accordingly enhances the dissociation ability of the plasma.…”

“…Zhang et al 18 used SiCl 4 as the deposition precursor and achieved an enhanced deposition rate of 0.17 nm s À1 in cold plasma, which is still too low for industry application. Considering that the traditional cold plasma enhanced CVD process is hard to convert massive SiCl 4 quickly and high efficiently, we propose an atmospheric pressure thermal plasma enhanced CVD (APTPECVD) process for nc-Si:H fabrication.…”

Mixed phase silicon thin films grown at high rate using 60 MHz assisted VHF-PECVD technique

“…With increase in argon flow more atomic hydrogen (H n ) are generated with dissociation of H 2 molecules. These atomic hydrogen (H n ) proved to be energetic in dissociation of SiH 4 and in modification of microstructure [57]. Due to difference in reaction rate of Ar n and Ar þ the concentration of radicals (SiH 3 , SiH 2 , SiH) is different in plasma.…”

Optical emission spectroscopy diagnostic and thermodynamic analysis of thermal plasma enhanced nanocrystalline silicon CVD process

“…A nc-Si:H deposition rate up to 9.78 nm s À1 was achieved, which is much higher than the maximum deposition rate as reported. 1,15 The silicon deposition rate and product properties of SiCl 4 -H 2 system exhibit strong dependence on the input rate of SiCl 4 and the dilution ratio H 2 /SiCl 4 . Optical emission spectroscopy (OES) diagnostic and equilibrium calculation has been carried out in this work to better understand this relationship.…”