Effect of H2 dilution on the growth of low temperature as-deposited poly-Si films using SiF4/SiH4/H2 plasma

Abstract

We have studied the effect of H2 dilution on the growth of polycrystalline silicon (poly-Si) using SiF4/SiH4/H2 by a remote plasma chemical vapor deposition. With an increase of H2 dilution ratio the grain size decreases and the polycrystalline fraction increases, probably due to enhancement of the nucleation rate with H2 flow rate. We have deposited polycrystalline silicon films with a crystalline fraction of 89% at a substrate temperature of 330 °C. The peak of the deconvoluted Raman spectrum contributed from the microcrystalline (or amorphous) Si portion in the deposited poly-Si film increases and the full width at half maximum decreases with increasing H2 flow rate.

Characterization of structure and role of different textures in polycrystalline Si films

“…With an increase in the exposure time for the H 2 plasma, the d h1 1 0i values largely decreased and the d h1 1 1i values were unchanged, exhibiting roughly fixed I XRD values at the h1 1 0i direction and I XRD values at the h1 1 1i direction. These results suggest that the H 2 plasma exposure enhanced the h1 1 0i nucleation, in agreement with the previous result that showed that an increase in [H 2 ] for PECVD poly-Si films causes enhanced nucleation leading to both a decrease in d and an increase in the number of grains [11].…”

“…Furthermore, an increase in [H 2 ] decreased the grain sizes along with an increase in the nucleation rate [11]. On the other hand, Matsuda [12], suggested that H-coverage on the growing surface of poly-Si films assists the crystallization, through enhanced surface migration of adsorbates [3,12].…”

Origin of photoluminescence in nanocrystalline Si:H films

“…It has been reported that the enhanced nucleation on the growing surface during deposition of nc-Si can be achieved by increasing the hydrogen flow rate, [H 2 ] [51,52], or the deposition temperature, T d [53]. However, the increase in T d also caused an increase in d. Thus, the increase in [H 2 ] leads to reduction of d [51,52], while the increase in T d should lead to increase in d [53]. Furthermore, it has been reported that formation of nc-Si is due also to higher etching activity of hydrogen radicals for the amorphous phase than the crystalline one [26,27].…”

High quality nanocrystalline silicon thin film fabricated by inductively coupled plasma chemical vapor deposition at 350°C

“…High quality nc-Si film with high crystallinity and no incubation layer was fabricated by ICP-CVD without employing any additional techniques such as a deposition of a seed layer prior to the nc-Si deposition or a use of SiF 4 , SiH 2 Cl 2 or a plasma treatment on the surface [6,[13][14][15][16][17]. The fabrication of nc-Si film with dense crystalline structure in our experiment can be attributed to ICP-CVD which generates remote plasma of high density [10][11][12] and use of He as a dilution gas instead of H 2 [18].…”