Microcrystalline Silicon Growth: Deposition Rate Limiting Factors

Abstract

Microcrystalline silicon films were deposited on corning glass substrates both by the standard hydrogen dilution and the layer-by-layer (LBL) technique. In-situ UV-visible spectroscopic ellipsometry measurements were performed to analyze the evolution of the composition of the films.The change of the hydrogen plasma conditions by increasing the pressure in the LBL process leads to a faster kinetic of crystallization and to an increase of the deposition rate by a factor of two. The increase of the pressure and the decrease of the inter-electrode distance allowed to increase the deposition rate from 0.26 to 3 A/s in the hydrogen dilution technique. Interestingly enough, the crystalline fraction of the films remains higher than 50%. However, as the deposition rate increases the growth process results in a slower kinetic of crystallization with a long range evolution of the film composition (up to 0.5 ýtm).

Stable microcrystalline silicon thin-film transistors produced by the layer-by-layer technique

“…This deposition rate can be increased up to 1 Å/s by an appropriate choice of the plasma conditions. 22 In principle, all of the plasma processes could have been carried out in a single PECVD system, but at the moment, we have different processes optimized in different deposition systems.…”

Highly Microcrystalline Phosphorous‐Doped Si:H Very Thin Films Deposited by RF‐PECVD

“…In undoped μc‐Si:H, an increase in R H is known to impact strongly X c until a sharp transition from amorphous to crystalline phase occurs, [ 12,13 ] usually for R H > 20 in our conditions. High compressive stress was observed in P doped μc‐Si:H by Wei et al [ 14 ] in similar experimental conditions.…”

“…It must be pointed out that thinner amorphous incubation layers have been obtained for μc-Si:H by using a two-step, layer-by-layer process. [9,13,17] However, these layers were undoped and as seen in Figure 1a the addition of phosphine to the gas mixture prevents crystalline phase nucleation. Thinner incubation layers may also be obtained by further increasing the hydrogen dilution factor R H , at the cost of a low deposition rate.…”

New approaches for the production of nano‐, micro‐, and polycrystalline silicon thin films

“…If the deposition rate is too high or the hydrogen flux too low, the critical concentration for nucleation will not be reached at the beginning of deposition but after some time and an amorphous or partly crystallized interface will be left behind. Thus, the higher the deposition rate, the thicker the interface layer, which can reach a fraction of a micron for high rates [55]. This evolution of the film properties during growth has been studied by in situ ellipsometry and leads to the so-called protocrystalline silicon thin films [56], which corresponds to the incubation and nucleation phases of microcrystalline silicon [57].…”