A method for depositing a film on a substrate is provided. In one aspect, the method includes providing a metal-containing precursor to an activation zone, and activating the metal-containing precursor to form an activated precursor. The activated precursor gas is transported to a reaction chamber, and a film is deposited on the substrate using a cyclical deposition process, wherein the activated precursor gas and a reducing gas are alternately adsorbed on the substrate. Also provided is a method of depositing a film on a substrate using an activated reducing gas.

Method of film deposition using activated precursor gases

Silent-discharge driven excimer UV sources and their applications

It is now a widespread view that a high-Jc superconducting wire with a high performance under strong magnetic fields at liquid-nitrogen temperature needs to be realized by the material Y-123. However, because of the weak linking nature of this material, the fabrication of the wire must be based on a coated-conductor process to achieve a highly textured Y-123 thin film on a long starting wire tape. Various attempts to obtain a textured substrate with sizable length have been made by various methods, with or without the aid of buffer layers. Approaches to the fabrication of an epitaxial thin film of Y-123 have also been made from vapour, liquid, or solid phases by different methods. Therefore, combinations of these proposed processes in each category have led to several promising on-going worldwide approaches to achieve the realization of practical coated superconducting wires in the near future. This review focuses on the most outstanding achievements in Japan.

https://iopscience.iop.org/article/10.1088/0953-2048/13/1/310/pdf

High-temperature-superconductor coated conductors: technical progress in Japan

Fundamental Aspects of Photochemical Vapor Deposition Reactors, Optical Sources, and Associated Equipment Metal Films Semiconductors Dielectrics Miscellaneous Materials and Applications Surface Processing Future Prospects and Conclusions References Index

Photochemical vapor deposition

Monolayer atomic layer epitaxy of GaAs has been achieved between 430 and 500 °C by using alternating pulses of AsH3, Ga(CH3)3, and atomic hydrogen Maintaining the susceptor temperature below 500 °C suppresses the unfavorable thermal decomposition of Ga(CH3)3 to Ga in the gas phase The basic point of our growth method is that, notwithstanding these low temperatures, sufficiently fast surface kinetics for growth are maintained by activation with the atomic hydrogen pulses

Atomic layer epitaxy of gallium arsenide with the use of atomic hydrogen

The downstream region of a near afterglow plasma (Δt=100 μs) has been used to decompose trimethylgallium (TMGa) and the products analyzed using a mass spectrometer. The major TMGa dissociation products with a hydrogen plasma were identified as methane and ethane while with a helium plasma ethane, ethylene, and acetylene were the main dissociation species. Time‐resolved optical emission originating from the downstream reaction zone shows that decomposition of TMGa occurs primarily via photodissociation with the hydrogen plasma while both photon and metastable species (He 21 S and 23 S) contributed to the TMGa decomposition with the helium plasma. VUV transmitting and VUV absorbing windows placed between the upstream hydrogen plasma and the downstream TMGa source provided further direct evidence of the role of VUV photodissociation in the TMGa decomposition.

Decomposition of trimethylgallium in the downstream region of a near afterglow plasma

A windowless helium lamp is employed to assist chemical vapor deposition of hydrogenated amorphous silicon from disilane feedstock gas at a film growth rate greater than 200 A/min. Material properties in this preliminary study are comparable to the best hydrogenated amorphous silicon (a‐Si:H) films produced by conventional bulk plasma CVD techniques. The amount of photoconductivity degradation under long‐time illumination is more than plasma‐deposited a‐Si‐H thin films. Photoconductivity as high as σp =4×10−4 (Ω cm)−1 has been obtained.

Windowless helium lamp assisted chemical vapor deposition of hydrogenated amorphous silicon

Soft-vacuum-generated electron beams employed to create a large-area plasma for assisting chemical vapor deposition (CVD) of thin films are reviewed. The electron-beam plasma is used directly, where electron-impact dissociation of feedstock gases plays a dominant role, and indirectly in a downstream afterglow, where electron-impact dissociation of feedstock reactants plays no role. Photodissociation and metastable atom-molecule reactions dominate in the downstream afterglow. The transmitted beam spatial-intensity profiles are quantified from initial generation at a slotted line-shaped cold cathode through acceleration in the cathode sheath and propagation in the ambient gas. The vacuum ultraviolet (VUV) output spectrum and VUV generation efficiency from electron-beam-excited plasmas are measured. The properties of films deposited by direct electron-beam-generated plasma-assisted CVD and downstream afterglow CVD are reviewed and compared to conventional plasma-assisted CVD films. >

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A review of microelectronic film deposition using direct and remote electron-beam-generated plasmas

A ring shaped cold cathode electron gun provides a large area disc shaped vacuum ultraviolet (VUV) light source up to 20 cm in diameter. The windowless disc plasma is also a source of radical and excited atomic gas species. VUV photons, excited species, and radicals can all assist dissociation of CVD feedstock reactants via volume photo-absorption and sensitized atom-molecule collisions, respectively. In addition, the excited radical flux and VUV impingement on the film may also assist heterogeneous surface reactions and increase surface mobility of absorbed species. Thin films of aluminum nitride, Si3N4, and hydrogenated amorphous silicon have been deposited at temperatures between 100°C - 400°C. The deposited films show significant improvement over other photoassisted CVD processes in the film quality achieved, the substrate temperature required and the maximum deposition rates.

Windowless Wide Area Vuv Lamp for Energy Assisted CVD

A wide area disc shaped plasma source of 20cm in diameter generated by a ring shaped cathode electron beam is used to decompose Trimethylgallium (TMGa) and Trimethylarsenic (TMAs). Volume photo-absorption of VUV photons and sensitized atom-molecule collisions with excited species and radicals can all assist dissociation of the organometallic feedstock reactants. In addition, the excited radical flux and VUV impingement on the film may also assist heterogeneous surface reactions and increase surface mobility of absorbed species. Mass spectrometry studies using deuterium as a replacement for hydrogen as a trace gas allowed for the elicidation of decomposition pathways of TMGa and TMAs. Byproducts of hydrogen and helium plasmas were also studied.

Z. Yu

Papers

Decomposition of trimethylgallium in the downstream region of a near afterglow plasma

Windowless helium lamp assisted chemical vapor deposition of hydrogenated amorphous silicon

A review of microelectronic film deposition using direct and remote electron-beam-generated plasmas

Windowless Wide Area Vuv Lamp for Energy Assisted CVD

In-Situ Gas Conversion Using a Wide Area Disc Shaped He-H2 Plasma and Organometallic Feedstocks