Remote Microwave Plasma Chemical Vapor Research Articles

Point‐Arc Remote Plasma Chemical Vapor Deposition for High‐Quality Single‐Crystal Diamond Selective Growth

Selective growth techniques are believed to be the most effective approaches in the fabrication of diamond devices. Herein, the contamination from antenna and mask damage that causes poor performance in electronic applications is overcome with a high‐quality diamond film on Ib (100) substrate, obtained by utilizing point‐arc remote microwave plasma chemical vapor deposition (MPCVD). Scanning electron microscope (SEM) images and energy dispersive X‐ray (EDX) mapping suggest that the diamond nucleation and selective growth occurred only in unmasked regions. Crystalline quality is evaluated by Raman spectra. Mo concentration from the antenna is detected with secondary ion mass spectroscopy (SIMS) at only a background level in the selectively grown diamond, indicating that the films are free of contaminant from the antenna, at three orders of magnitude lower than the impurity concentration in films selectively grown by typical hot filament CVD. Moreover, the moderate growth rate (approximately 50 nm h−1) enables high reproducibility, which is of great importance for the precise control thickness of the selective growth layer, and thus the proposed method offers significant potential for the architecture modification of diamond devices.

Reactivity of organosilicon precursors in remote hydrogen microwave plasma chemical vapor deposition of silicon carbide and silicon carbonitride thin‐film coatings

AbstractA number of organosilicon precursors for silicon carbide and silicon carbonitride thin‐film coatings, such as silanes, carbosilanes, aminosilanes, and disilazane, respectively, were characterized in terms of their reactivity in a remote microwave plasma chemical vapor deposition process, which was induced using hydrogen as plasma generating gas. The process displayed high selectivity with respect to the activating species and the chemical bonds in the molecular structure of the precursors. In view of very short life times of excited hydrogen plasma species the activation step takes place with an exclusive contribution of ground‐state hydrogen atoms. The CH, CC, SiC, SiN, CN and NH bonds present in the molecules of the precursors are non‐reactive and only the SiH or SiSi bonds play a key role in the activation step. The reactivity of the precursors was characterized in a quantitative way by the yield of the film growth parameter. The yield parameter expressing the mass of film per unit mass of the precursor fed to the reactor was calculated from the slopes of linear plots of time dependencies of film mass and precursor mass, which were determined for each investigated precursor. The reactivity of the precursors was found to be strongly dependent on the number of the SiH units present in their molecules and those containing two SiH units appeared to be most reactive. Copyright © 2009 John Wiley & Sons, Ltd.

Photolytic absorbate removal during the growth of aluminium nitride by remote microwave plasma chemical vapour deposition

Filtered ultraviolet (UV) light was used to desorb impurities present at the growth front of aluminium nitride prepared by remote plasma enhanced chemical vapour deposition at room temperature. Trimethylaluminium and trimethylamine alane were used as metalorganics. Unfiltered ultraviolet light from a mercury arc lamp was found to inhibit film growth entirely; a glass plate with a short wavelength 10% transmission cutoff of 330 nm was therefore used as a UV filter. Substantial improvements in the insulating properties of the AlN films were observed for films grown with the filtered UV light present. Improvements in film morphology and an increase in breakdown fields were also observed. Further experiments with pyrex filtered UV light with a short wavelength 10% transmission cutoff of 283 nm were carried out, though better results were achieved with glass filtering.

Diffuse Reflectance Fourier Transform Infrared Spectrometry of BN Films Deposited on Steels by Remote Microwave Plasma CVD from Borazine

The diffuse reflectance Fourier transform infrared spectra of the boron nitride (BN) films deposited on steels by remote microwave plasma chemical vapour deposition (CVD) from borazine with nitrogen, hydrogen and argon were investigated in the wavenumber range of 400-4000 cm-1. It was found that the cubic BN formation depends on production of the intermediate species of cyclotriborazane ((BH2NH2)3) and its dehydrogenation. The structural bonds of cyclotriborazane are similar to that of cubic BN. Optimum conditions for deposited BN films were found to be the borazine-nitrogen mixture at the substrate temperature of 550°C. The BN films were a mixture of crystalline cubic BN accounting for the major content and hexagonal BN with relatively low hydrogen content.

Stability of ultrathin silicon nitride films on Si(100)

Ultrathin silicon nitride films on Si(100) have been studied using x-ray photoelectron spectroscopy, medium energy ion scattering, Raman spectroscopy, and variable-energy positron annihilation spectroscopy. Films ∼10-nm-thick were prepared by remote microwave plasma chemical vapor deposition. A compressive stress of about 0.4 GPa was found by measuring the Raman shift of the fifth-harmonic LO mode of the silicon substrate. The film properties, however, changed significantly upon vacuum annealing. Annealing at 100 °C for 1 h resulted in an increase of nitrogen concentration near the film surface, probably because of nitrogen surface segregation. Annealing at 100–500 °C also released film induced stress and a complete stress release was achieved by annealing at 500 °C for 1 h. Positron annihilation results showed that vacuum annealing only affected the film but not the substrate.

Reduced interface state densities for remote microwave plasma silicon nitride

The interface state density and fixed charge density of films of a-Si3N4:H deposited on silicon substrates by remote microwave plasma chemical vapour deposition have been studied as a function of deposition and annealing temperature. Interface state densities (Dit as low as 9 × 1010 cm−2 eV−1 have been obtained for films deposited at 215 °C and annealed for 15 min at 500 °C. The films exhibited positive fixed charge levels (QN/q)> 1013 cm−2, increasing slightly with deposition temperature and decreasing slightly with annealing at temperatures from 500 to 700 °C. Fourier transform infrared spectroscopy and Auger depth profiling were used to study the impurities in the films and at the interface. Metal–insulator–silicon field effect transistors made with these films showed room temperature effective channel hole mobilities of 37 cm2 V−1 s−1.

Properties of Ultrathin Amorphous Silicon Nitride Films on III V Semiconductors

ABSTRACTProperties of ultrathin (— lOnm) silicon nitride films on single crystal Si, InP and GaAs have been studied using Raman spectroscopy, medium energy ion scattering (MEIS), variable-energy positron annihilation spectroscopy and x-ray photoelectron spectroscopy (XPS). The silicon nitride films were prepared by remote microwave plasma chemical vapour deposition (RPCVD). The results showed that oxidation of the film due to air exposure was restricted to the near surface with an oxygen penetration depth no greater than 2 nm. The residual stress in the as-grown films was substrate-dependent. For films on Si (100), the film induced residual stress was compressive with a value of 0.5GPa. Annealing at 500°C for 60 minutes resulted in a complete release of the residual stress. Vacuum annealing at a temperature below 500° C also led to changes of the electrical properties in the films but not the substrate.

Growth and characterization of silicon nitride films produced by remote microwave plasma chemical vapor deposition

Films of silicon nitride have been grown in an ultrahigh vacuum system by the reaction of silane with nitrogen remotely excited in a microwave plasma at pressures in the range 0.1–0.9 Torr with substrate temperatures in the range 70–350 °C. Growth rates have been determined as a function of silane–nitrogen flow ratio, pressure, microwave power, and substrate temperature in order to give some insight into the growth mechanism. Results indicate that the rate of film deposition is governed by the arrival rate of active nitrogen species at the surface. The films have been characterized by 15N nuclear reaction profiling and Rutherford backscattering analysis to determine the hydrogen, silicon, and nitrogen contents. Hydrogen contents are comparable to those obtained with parallel-plate plasma enhanced chemical vapor deposition reactors while near stoichiometric, nitrogen rich films can be obtained over a wide range of deposition parameters. Floating double probe measurements used to obtain the electron temperatures and ion densities verify that substrate bombardment by charged or energetic particles is not a factor in the growth of these films.