Optimum Design of LPCVD Reactors

A general mathematical model for the description of heat transfer and mass transport processes in a hotwall multiple-wafer horizontal tube LPCVD reactor is developed. Investigations on the influence of the geometric characteristics of the reactor system on the thickness uniformity of the layers and on the economically expedient performance of the processes are carried out by the model. In this way, information about the optimum geometry of the reactor is obtained. Technical modifications of the conventional LPCVD systems are analyzed which allow the obtainment of uniform layers under conditions of mass production without applying temperature difference along the reaction zone. A model of injection-fed reactors is built that helps make conclusions about the optimum design of the injectors when they are used in a regime of maintaining constant concentration in the system

Kinetics of the initial stages of film formation during low pressure chemical vapour deposition of polysilicon by pyrolysis of silane

A kinetic model for description of the process of silicon film formation on silica by thermal decomposition of silane at reduced pressure has been proposed. The model is based on the concept of kinetic interdependence between heterogeneous catalytic chemical reaction and fundamental structure forming phenomena - nucleation and nuclei growth. A number of experimental data for deposition rates and polysilicon grains sizes have been mathematically processed in order to derive kinetic equations for the rates of nucleation and nuclei growth as functions of reactor operating conditions (pressure and temperature) as well as process duration. Furthermore, based on both the good correspondence achieved between the experimental results and the model, and the deductions of thermodynamic theory of nucleation, the kinetic equations derived were analysed in regard to the general description of silicon film structure evolution. The analysis of the model, by confïrming the general trends established between the arrival and the surface diffusion rates of silicon adspecies, contributes to clarify the mechanism of the initial stages of film microstructure formation. The results obtained show that kinetics of structure evolution can be successfully described by developing the existing CVD phenomenological kinetic models further to an atomistic level

Characterization of low-dielectric constant SiOCN films synthesized by low pressure chemical vapour deposition

Films composed of Si, C, O and N have been deposited by low pressure chemical vapour deposition (LPCVD) from different chemical systems : pyrolysis of C3N3Cl2N(SiMe3)2 and interaction between SiCl4, C2Cl4, NH3 and H2O vapour. The composition, chemical bonding and structure of the films were investigated by a variety of analytical techniques. The physicochemical and electrical properties of the layers were also studied and it was found that films exhibit low static dielectric constants in the ranges of 2.8 - 3.5 and 1.7 - 2.5 for the two chemical systems, respectively. These low-k values combined with the high density, good adhesion and chemical inertness of the films, make them very attractive for future device technology application

Physical properties of carbon nitride films synthesized using atomic transport reactions

Inductively coupled plasma chemical vapour deposition (ICP-CVD) has been used for the preparation of thin CNx films from a solid carbon source (at floating potential) and a nitrogen plasma. Volatile CN species generated via atomic transport reactions are the film forming particles. The deposited layers have a rather smooth surface; their deposition rate and thickness, respectively, depend on the substrate position due to a gradient in the precursor species concentration. The nitrogen fraction is at about 50% and exhibits almost no dependence on the deposition parameters. Emphasis was placed on a detailed study of the bonding structure by different analytical techniques. Based on these investigations, a probable structure of the CNx films is proposed. Since no identification of tetragonally bonded carbon atoms was found, it is supposed that the bonding network is composed of imine-like units and only to a small part of nitrile-type elements. The films are insulating with resistivity of up to 1011Ωcm. © 2000 Elsevier Science S.A.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Investigation of the thermal stability of nitrogen-rich amorphous carbon nitride films

The thermal stability of nitrogen-rich amorphous carbon nitride films (N/C≥1) is investigated from room temperature up to 600 °C. The films were deposited by three different methods, namely pulsed laser deposition (PLD), inductively coupled plasma chemical vapour deposition (ICP-CVD) with gaseous precursors, and ICP-CVD utilizing transport reactions. As-deposited and annealed films were characterized with respect to their thickness, composition and bonding structure by a variety of methods including wavelength dispersive X-ray analysis (WDX), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR). Annealing at 200 °C leads to desorption of surface contaminants while in the range between 200 and 400 °C a significant densification is observed. Above 400 °C a drastic loss of film material, especially nitrogen-rich groups, sets on, leading to the total destruction of the films at 600-700 °C. These observations are compared with the annealing behaviour of films with lower nitrogen content.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Comparative characterization of nitrogen-rich CNx films prepared by different ICP-CVD techniques

Thin amorphous nitrogen-rich CNx films (N/(C+N) ≥ 0.5) have been prepared by two inductively coupled plasma chemical vapour deposition (ICP-CVD) techniques: using transport reactions from a solid carbon source and from CCl4/NH3/Ar and CCl4/N2/H2/Ar gas mixtures. Optical emission spectroscopy (OES) and quadrupole mass spectrometry were used to derive information about the plasma properties. The composition of the films was investigated by Anger electron spectroscopy (AES), wavelength dispersive X-ray (WDX) and elastic recoil detection (ERD) analyses, and the chemical bonding structure by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. In addition, several application relevant properties (mechanical, optical, electrical) of the nitrogen-rich CNx films were studied. The results of both deposition methods were compared and discussed on the base of the specificities of the processes.13th European Conference on Chemical Vapor Deposition (EUROCVD 13); Athens; Greece; 26 August 2001 through 31 August 2001.info:eu-repo/semantics/publishe