Plasma-enhanced chemical vapor deposition of boron nitride thin films from B2H6–H2–NH3 and B2H6–N2 gas mixtures

Abstract

Highly transparent and stoichiometric boron nitride ͑BN͒ films were deposited on both electrodes ͑anode and cathode͒ of a radio-frequency parallel-plate plasma reactor by the glow discharge decomposition of two gas mixtures: B 2 H 6 -H 2 -NH 3 and B 2 H 6 -N 2 . The chemical, optical, and structural properties of the films, as well as their stability under long exposition to humid atmosphere, were analyzed by x-ray photoelectron, infrared, and Raman spectroscopies; scanning and transmission electron microscopies; and optical transmittance spectrophotometry. It was found that the BN films grown on the anode using the B 2 H 6 -H 2 -NH 3 mixture were smooth, dense, adhered well to substrates, and had a textured hexagonal structure with the basal planes perpendicular to the film surface. These films were chemically stable to moisture, even after an exposition period of two years. In contrast, the films grown on the anode from the B 2 H 6 -N 2 mixture showed tensile stress failure and were very unstable in the presence of moisture. However, the films grown on the cathode from B 2 H 6 -H 2 -NH 3 gases suffered from compressive stress failure on exposure to air; whereas with B 2 H 6 -N 2 gases, adherent and stable cathodic BN films were obtained with the same crystallographic texture as anodic films prepared from the B 2 H 6 -H 2 -NH 3 mixture. These results are discussed in terms of the origin of film stress,the effects of ion bombardment on the growing films, and the surface chemical effects of hydrogen atoms present in the gas discharge.

Gas Phase Chemistry of Trimethylboron in Thermal Chemical Vapor Deposition

“…Thin film synthesis of boron-containing materials, especially carbides (B 4 C), nitrides (BN), and metal borides (e.g., TiB 2 ), have been studied by chemical vapor deposition (CVD) methods using boron halides and hydrides as boron precursors in a hydrogen ambient. − Boron hydrides, mainly diborane (B 2 H 6 ), have been widely used for semiconductor applications as they require lower deposition temperatures and provide films with a low level of contamination. However, diborane is highly toxic and explosive, making its handling and storing troublesome.…”

Flexible Borane–Nitrogen Frustrated Lewis Pair Organic Microsphere for Selective Alkyne Hydrogenation

“…At the same time, new peaks formed at 1156 cm –1 for BNP-1 in both cases, which were ascribed to the bending vibration of B–H bond . Together with the perceived weak stretching vibration signal of B–H centered around 2590 cm –1 , a transformation of B–OH­(R) to hydroborane B–H was envisioned. This is in line with the previously reported mechanism and can well explain our experimental observation of the inflection point in the reaction evolution chart, during which the truly active B–H species was constantly formed and accumulated (B–H formation stage), thus resulting in a low but increasing substrate conversion rate.…”

Elastic Electron Scattering by Diborane(6) and Diborane(4) Molecules

“…One of the most important applications of diboranes is in the area of plasmas, for example, the B 2 H 6 [diborane(6)] molecule is used as a precursor for the plasma-assisted deposition of cubic boron nitride films of high hardness and high chemical resistance. , In addition, doping of silicon with boron is used in applications for semiconductor devices, where it is successfully achieved by different methods in gas mixtures containing diborane . Diborane gas has been widely used for either conventional ion implantation or plasma doping to form a p + /n junction .…”