Growth of Amorphous and Crystalline Silicon by HR-CVD (Hydrogen Radical Enhanced CVD)

Microcrystalline Silicon by Dc Magnetron Sputtering: Growth Mechanisms

We have used real-time, in situ spectroscopie ellipsometry (SE) and infrared reflectance (IR) to study microcrystalline silicon (μc-Si) formation in reactive magnetron sputtering (RMS). μc-Si growth occurs at high hydrogen partial pressures and moderate substrate temperatures. We use IR studies and SE studies of film growth on rough surfaces, respectively, to show that these conditions lead to high hydrogen coverage of the film surface and high effective surface diffusivity. The interface region is amorphous and its thickness decreases with deposition rate. For a fixed growth flux, we observe a 30% decrease in the deposition rate of μc-Si relative to the amorphous interface region. This could be due to increased etching or decreased sticking coefficients during microcrystalline growth.

Nucleation and Growth in Vicinity of Growing Surface in Making Microcrystalline Silicon

A close study was conducted on microcrystalline Silicon (μc-Si) prepared by PE-CVD (Plasma Enhanced CVD) from SiF4 with the assistance of atomic hydrogen. The atomic hydrogen played a major role in either making precursors, SiFnHm (n+m=3), by gas phase reactions with the fragments, SiFn (≤3), or constructing Si-network in the vicinity of the growing surface. Proper conditions of nucleation were markedly different from those of growth with respect to parameters, flow of atomic hydrogen and substrate temperature.

Control of Chemical Reactions for Growth of Crystalline Si at Low Substrate Temperature

A systematic study has been made on the formation of Si-network of amorphous(a-), microcrystalline(μc-) and epitaxial (epi)-Si prepared by Plasma-Enhaced (PE-) CVD under control of flow of atomic hydrogen. The control of the Si-network structures requires a deliberate selection of the precursor, i.e., SiHn (n≤53) and SiFnHm (n+m≤53), as well as an intentional acceleration of the chemical reactions for the propagation of Si-network in the vicinity of the growing surface by impinging of atomic hydrogen. A plausible interpretation was given to the growing mechanism of c-Si at low temperature.

Role of Surface and Growth-Zone Reactions in the Formation Process of µc-Si:H

The role of the surface reaction is discussed in the formation process of µc-Si:H in comparison to that of a-Si:H. It is suggested that the responsible radicals for the formation of µc-Si:H are SiH3 as same in the case of a-Si:H depositions. On the top film-growing surface, a lot of H atoms reach the surface during the course of the μc-Si:H growth giving rise to the change in the surface condition, i. e. the loss probability of SiH3 radicals is increased. At the same time, a full H-coverage of the surface is expected which enhances the surface diffusion of SiH3 radicals, leading to the appearance of a gc nucleus. Moreover, it is speculated that the reaction in the growth zone is not necessary for the nucleation process in µc-Si:H.