多晶硅薄膜低温生长中晶粒大小的控制

以SiCl4H2为气源,用等离子体增强化学气相沉积(PECVD)方法低温快速沉积多晶硅薄膜.实验发现,在多晶硅薄膜的生长过程中,气相空间各种活性基团的相对浓度是影响晶粒大小的重要因素,随功率、H2/SiCl4流量比的减小和反应室气压的增加,晶粒增大.而各种活性基团的相对浓度依赖于PECVD工艺参数,通过工艺参数的改变,分析生长过程中空间各种活性基团相对浓度的变化,指出“气相结晶”过程是晶粒长大的一个重要因素. 关键词： 气相结晶 多晶硅薄膜 晶粒生长 SiCl4     

Evolution of the fractal surface of amorphous lead zirconate-titanate films during crystallization

The recrystallization kinetics of amorphous lead zirconate-titanate films prepared by sol-gel technology are investigated experimentally using elastic scattering of light. Sequences of elastic dependences of the scattered light intensity are recorded directly during thermal annealing. The evolution of the morphology of the film surface during annealing is described in terms of the variation of their fractal dimensionalities D _s. The experimental dependences D _s(t) are compared with the results of a computer simulation of the phase transition kinetics in a thin plate (film). Fiz. Tverd. Tela (St. Petersburg) 41, 306–309 (February 1999)     

Photothermal detection of surface states in amorphous silicon films

A new method for the determination of surface states in amorphous silicon films is proposed. The method is based on the observation of enhancement of the interference fringe amplitude in photothermal deflection spectra, due to the presence of surface states.A theoretical approach is presented, together with the experimental results and an evaluation of the density of surface states. The method proves to be adequate, in most cases, to yield results in good agreement with those reported in literature.     

Repolarization studies in amorphous and polycrystalline silicon

A procedure has been developed to extract qualitative and quantitative information on the muonium fractions, in particular the Mu^* fraction, in polycrystalline and amorphous materials from their longitudinal field repolarization curves. Preliminary results for amorphous silicon suggests that both the Mu^* and Mu^* fractions here are generally lower than in crystalline silicon at temperatures below 200K, but the Mu^* fraction may survive to room temperature in this disordered host.     

Evolution of microstructure in polycrystalline silicon thin films upon excimer laser crystallization

Polycrystalline silicon (poly-Si) films fabricated by pulsed excimer laser crystallization (ELC) have been investigated using time-resolved optical measurements, scanning-electron microscopy, and cross-sectional transmission-electron microscopy. Detailed crystallization mechanisms are proposed to interpret the microstructure evolution of poly-Si films for both frontside and backside ELC. It is found that the backside ELC is a good candidate for the manufacturing of low-temperature polycrystalline silicon because of the high laser efficiency and low surface roughness of the poly-Si films.     

Temperature dependence of the surface reactivity of SiH3 radicals and the surface silicon hydride composition during amorphous silicon growth

For hydrogenated amorphous silicon (a-Si:H) film growth governed by SiH₃ plasma radicals, the surface reaction probability β of SiH₃ and the silicon hydride (-SiH_x) composition of the a-Si:H surface have been investigated by time-resolved cavity ringdown and attenuated total reflection infrared spectroscopy, respectively. The surface hydride composition is found to change with substrate temperature from -SiH₃-rich at low temperatures to SiH-rich at higher temperatures. The surface reaction probability β, ranging from 0.20 to over 0.40 and with a mean value of β=0.30±0.03, does not show any indication of temperature dependence and is therefore not affected by the change in surface hydride composition. It is discussed that these observations can be explained by a-Si:H film growth that is governed by H abstraction from the surface by SiH₃ in an Eley-Rideal mechanism followed by the adsorption of SiH₃ at the dangling bond created.     

Specific heat of amorphous and polycrystalline lead-bismuth films

The specific heat of Pb₇₀Bi₃₀-films produced by quench condensation has been measured in the amorphous and the polycrystalline phase at temperatures between 0.5 K and 2 K. No evidence could be found for theT-proportional term which has been observed on many amorphous dielectrics.These results completely agree with the observations on amorphous Bi-films and confirm once more the assumption that the existence of covalent bonds in addition to the structural disorder is essential for the occurrence of a linear term in the temperature dependence of the lattice heat.     

Analyzing in-plane magnetic anisotropy from surface morphology for amorphous films

A method is developed to analyze the in-plane magnetic anisotropy from surface morphology for amorphous films. The lateral sizes along radial direction (R_RD) and tangent direction (R_TD) of rotational substrate, which are extracted from the surface morphology of Co_66.3Zr_33.7 amorphous films, are used to calculate stress anisotropy energy E_σ. It is found that E_σ is consistent with the magnetic anisotropy energy K_μ for the samples deposited on Si (1 0 0) substrate and then a relationship K_μ ∝ 1/R_RD − 1/R_TD can be obtained. This method is sensitive to the initial state of substrate so its application range is discussed.     

The study of amorphous incubation layers during the growth of microcrystalline silicon films under different deposition conditions

<正>The structural un-uniformity of μc-Si:H films prepared using a very high frequency plasma-enhanced chemical vapour deposition method has been investigated by Raman spectroscopy,spectroscopic ellipsometer and atomic force microscopy.It was found that the formation of amorphous incubation layer was caused by the back diffusion of SiH_4 and the amorphous induction of glass surface during the initial ignition process,and growth of the incubation layer can be suppressed and uniformμc-Si:H phase is generated by the application of delayed initial SiH_4 density and silane profiling methods.     

Cobalt-induced polycrystalline silicon film growth

Cobalt (Co)-induced crystalline silicon (Si) growth was investigated. The Co catalyst reacted to dc magnetron sputtered Si at 600 °C forming a Co silicide layer. The polycrystalline Si (poly-Si) was epitaxially grown above the Co silicide template, which has a small lattice misfit to Si. Annealing followed to improve the Si crystallinity. X-ray diffraction was performed to trace Co silicide phase formation and transition. The Co-rich silicide phase transitioned to CoSi₂ by annealing. The crystallinity of Si films was identified using reflection absorption Fourier transform-infrared spectroscopy, which detected unique peaks at 689 and 566 cm⁻¹ after the annealing process. The thin poly-Si film was used to fabricate a Schottky diode to prove the electronic quality. A good quality Si thin film was achieved by the metal-induced Si growth.     

Doping of evaporated amorphous silicon films

It is shown that evaporated amorphous silicon films can be doped interstitially by ion implantation and in-diffusion of lithium. The doping effect is smaller than for glow discharge silicon films, and the doped state is less stable at elevated temperature. This is explained by precipitation as well as out-diffusion effects in connection with the high defect concentration in evaporated films.     

Plasma deposition of hydrogenated amorphous silicon: Studies of the growth surface

This review focusses on the plasma-surface interactions and surface processes involved in a-Si: H thin film growth. We restrict our discussion of growth fluxes to a summary, and do not address plasma kinetics. In recent years, powerful in situ experiments have been carried out on the growing film surface, which reveal the adsorption, penetration, reaction, and elimination of precursor species, as well as the atomic-scale morphology and composition of the growth zone. Good data sets are available both for PACVD and reactive magnetron sputter deposition. These form an interesting comparison, since the former process is dominated by the hydrogen-rich radical SiH₃ at low energy, and the latter by energetic atomic Si and H. We review the key experiments and conclusions, underlining those aspects which are well established and those which remain qualitative; and we discuss the transition from amorphous to fine-grained polycrystalline film growth at high hydrogen pressures in terms of the surface mechanisms. This field is now entering a scientific stage where a detailed theory of low-temperature, plasma-assisted growth can be developed.     

Crystallization of amorphous silicon beyond the crystallized polycrystalline silicon region induced by metal nickel

Crystallization of amorphous silicon(a-Si) which starts from the middle of the a-Si region separating two adjacent metal-induced crystallization(MIC) polycrystalline silicon(poly-Si) regions is observed. The crystallization is found to be related to the distance between the neighboring nickel-introducing MIC windows. Trace nickel that diffuses from the MIC window into the a-Si matrix during the MIC heat-treatment is experimentally discovered, which is responsible for the crystallization of the a-Si beyond the MIC front. A minimum diffusion coefficient of 1.84×10~(-9)cm~2/s at 550℃ is estimated for the trace nickel diffusion in a-Si.     

Specific features of morphology and the structure of nanocrystalline cubic silicon carbide films grown on a silicon surface

Physics of the Solid State - The composition, surface morphology, and crystal structure of nanocrystalline cubic silicon carbide films grown on a silicon surface through chemical conversion from...     

Effect of oligomers on the growth of amorphous silicon films in a PECVD reactor

A plasma-chemical model of processes in a PECVD reactor is constructed that is an extension of the earlier model and takes into account the formation of oligomers Si_nH_m (n ≤ 5). The corresponding scheme of chemical reactions is developed, and simulation of film growth is carried out. It is found that Si₂H₅ and Si₃H₇ components strongly influence the film growth. It is of interest to obtain more reliable experimental data dramatizing these effects.     

Effect of the amorphous thin layer on the surface growth of amorphous/crystalline binary multilayer films

The effect of the amorphous thin layer on the surface growth of amorphous/crystalline binary multilayer films has been studied by using a continuum model. It is shown that both the surface roughness and the growth exponent of amorphous/crystalline binary multilayer films decrease with increasing thickness ratio between amorphous and crystalline layers. Our simulations have also revealed, in contrast to the monotonous rise in surface roughness observed in single-layer films grown on flat substrates, the surface growth of a multilayer film consists of two processes: interface smoothing and roughening, namely the film roughness decreases during the growth of amorphous thin layers but increases monotonously during the growth of crystalline thin layers. The observed interface smoothing and roughening can be obviously influenced by the change in the thickness ratio between amorphous and crystalline layers. The rise in thickness ratio between amorphous and crystalline layers enhances the interface smoothing effect but lowers the interface roughening effect and consequently shows a marked smoothing effect on the surface roughness.