The crystallization of undoped amorphous silicon films deposited by low‐pressure chemical vapor deposition in the temperature range 580–530 °C and annealed from 550 to 950 °C has been studied by transmission electron microscopy. The average grain size of the crystallized films depends on the annealing temperature and the deposition conditions. The nucleation rate of new grains during annealing decreases as the deposition temperature decreases from 580 to 545 °C and/or when the deposition rate increases. The final grain size is also influenced by the annealing temperature with the largest grain size obtained at low annealing temperatures. A simple model is described which explains the dependence of grain size on the annealing temperature. An average grain size of 500 nm has been obtained in a 200‐nm film deposited at 545 °C and annealed at 550 °C.

Large grain polycrystalline silicon by low‐temperature annealing of low‐pressure chemical vapor deposited amorphous silicon films

We present a thorough study of the microstructure, texture, intrinsic stress, surface, and interface morphology of transition metal nitride (mainly TiN but also CrN) films grown on Si by reactive sputter deposition, with emphasis to the mechanisms of adatom migration on the surface and subplantation of energetic species. In order to study the effects of adatom mobility and the subplantation probability we vary the ion energy and growth temperature. For the experimental part of this work we used nondestructive, statistically reliable x-ray techniques (diffraction, reflectivity, scattering). The x-ray results are compared and correlated with supporting data of in situ spectroscopic ellipsometry as well as Monte Carlo simulations of the irradiation effects and surface diffusion of adatoms. We found that the texture and the surface and interface morphology are sensitive to the mechanism of dissipation of the impinging ions. If the energy is enough to overcome the subplantation threshold (∼50eV), then the film...

Surface kinetics and subplantation phenomena affecting the texture, morphology, stress, and growth evolution of titanium nitride films

Evolution with thickness of the structure of the polycrystalline silicon (poly‐Si) films prepared at 300 °C has been studied by plasma decomposition of SiF4/SiH4/H2 source gases. The poly‐Si films with varied thickness are characterized mainly by Raman spectroscopy, x‐ray diffraction (XRD), and supplementarily by reflection high‐energy electron diffraction, transmission electron microscopy, Fourier‐transform infrared (FT‐IR) spectroscopy, electron‐spin resonance (ESR), and secondary‐ion‐mass spectroscopy (SIMS) measurements. The crystalline fraction of the film was calculated to be 87% by deconvoluting the Raman spectra. The grains indicated a strong 〈110〉 preferred orientation by XRD. The thickness (d) dependence of the diffracted (220) intensity is divided into three regions: an incubation region (d<200 nm, region 1), a linear region (200 nm ≤d<300–500 nm, region 2) where the deposition parameter (SiF4 flow rate, substrate temperature, and rf power) dependence is weak, and a linear region with steeper (or more moderate) slopes (300–500 nm≤d, region 3) where the deposition parameter dependence is large. The measurements of the angular distribution of the 〈110〉 grains reveal that they contain slanting ones by more than 4° in region 2, while they disappear in region 3. The FT‐IR and SIMS measurements for typical samples (Ts = 300 °C, 300 Pa) indicate that the grain boundaries are passivated by hydrogen in the bonding configurations of Si—Hn (n=1–3) and its concentration is approximately 3 at. %. The residual fluorine in the film is found to be much fewer (6×1019 cm−3) than hydrogen. It is found that the density of unpassivated dangling bonds indicates a low value of 1.1×1017 cm−3 for the film with d=280 nm by ESR measurements. The origin of the preferred orientation is also discussed on the basis of a model in which nucleation, ledge formation, and etching processes are considered.

Structural properties of polycrystalline silicon films prepared at low temperature by plasma chemical vapor deposition

Structure and crystal growth of undoped, as‐deposited, and annealed silicon films prepared by chemical vapor deposition (CVD) and low‐pressure chemical vapor deposition (LPCVD) of silane have been studied with use of x‐ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM). The grain size and a complete texture analysis are performed on CVD films grown at atmospheric pressure and temperature range 600≤Td≤805 °C, LPCVD films grown in the pressure range 0.1≤Pd≤2 Torr and temperature range 500≤Td≤650 °C and annealed amorphous CVD and LPCVD films near Ta=600 °C. We obtain systematically amorphous, strong 〈220〉 polycrystalline, and inhomogeneous partially crystallized films 〈111〉 or 〈311〉 oriented depending on the deposition conditions. The presence of a given texture is explained by a model which takes into account the specific free surface energies of the starting equilibrium forms and the extinction of some crystalline planes by {111} slow growing facets. The appearance of the 〈220〉 tex...

Structure and crystal growth of atmospheric and low-pressure chemical-vapor-deposited silicon films

Solid phase crystallization of thin films of undoped amorphous Si prepared by plasma enhanced chemical vapor deposition has been studied by transmission electron microscopy (TEM). From the TEM images, the thermodynamic parameters for the amorphous and crystalline phases were extracted. These parameters were compared with those previously reported for evaporated, chemical vapor deposited, and self‐implanted amorphous Si. We conclude that the thermodynamic parameters are very similar for different amorphous Si films, although the initial structure of the films is comparatively different from one to another. To explain this, the existence of an intermediate amorphous state is assumed and discussed.

Solid phase crystallization of thin films of Si prepared by plasma‐enhanced chemical vapor deposition

Crystallization study of chemically vapour-deposited amorphous silicon films by in situ x-ray diffraction

We have examined the structural properties of films grown by CVD in the range of temperatures 600-750°C. with particular emphasis on the volume repartition of crystals for films deposited around the crystallization temperature. We find that the general crystallization mechanism which determines the structure is one of deposition of an amorphous material followed by subsequent solid phase crystallization during the deposition time. This solid phase process occurs through a dominant nucleation at the film-substrate interface. The implications of this on the physical properties and morphology of these films will be discussed. We present a study of the crystallization process for silicon films prepared by chemical vapor deposition (CVD) from silane.(SiH4) at atmospheric pressure on fused silica substrates. The study concerns crystallization during deposition and by subsequent annealing, which has been the subject of a number of previous reports [l-31 describing X-ray texture, crystallization rates, conductivity changes, etc... Relatively minor attention has been paid to volume repartition of crystals within the film [ 41 . In this study, we have concentrated on this question and found that partially crystallized films are, under many conditions, inhomogeneous in depth with a repartition indicative of the dominance of an heterogeneous nucleation mechanism at the filmsubstrate interface. We discuss the implications of these findings as regards measurements of crystallization rates and morphology of polycrystalline films. The films have been prepared in a CVD reactor (Applied Materials AMV 800) industrially used for classical Si/Si epitaxy at atmospheric Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1982137 C 1 2 7 2 JOURNAL DE PHYSIQUE pressure. Pure silane (1 1 min-1) was diluted in hydrogen (32 1 min-l) into a vertical open-flow reactor with a silicon carbide susceptor heated by induction. n-type doping has been achieved by mixing phosphine (pH3) with silane. Films thicknesses are of the order of 1 pm. The growth rates of undoped and lightly doped films ([PH31/CSiH41 = 20 ppm) as a function of the deposition temperature are shown in figure 1. An activation energy of 2.2 eV is obtained for the growth rate. This value is higher than that reported in experiments at higher deposition temperature C51 or using nitrogen or helium as carrier gas C2, 31 but is very near of the value recently reported by Beers and Bloem C61 under similar experimental conditions.

R. Bisaro

Papers

Structure and crystal growth of atmospheric and low-pressure chemical-vapor-deposited silicon films

Crystallization study of chemically vapour-deposited amorphous silicon films by in situ x-ray diffraction

Structural and electronic properties of cvd silicon films near the crystallization temperature