Ronald A. Rudder

Chemical vapor deposition of diamond films from water vapor rf-plasma discharges

Polycrystalline diamond films have been deposited from water vapor rf‐plasma discharges at 1.0 Torr containing various alcohol vapors. No other gases such as H2, F2, or Cl2 were admitted to the growth chamber. Scanning electron microscopy and Raman spectroscopy have been used to characterize the diamond films. In addition, a water‐ethanol mixture has been used for homoepitaxial deposition with a full‐width‐half‐maximum narrower than the bulk substrate (2.60 and 2.75 cm−1, respectively). This technique represents a remarkable new approach to the growth of diamond which does not depend on delivery of hydrogen, fluorine, hydrocarbon, or halocarbon gases that have been typically used by other workers. The nucleation density and topography of the polycrystalline diamond films deposited from the water alcohol mixtures are quite sensitive to the choice of alcohol. Water vapor discharges, by producing H atoms and OH radicals, become the functional equivalent to molecular H2 discharges producing H atoms characteri...

Two-dimensional model of a large area, inductively coupled, rectangular plasma source for chemical vapor deposition

A novel design for an inductively coupled, rectangular plasma source is described. The design encompasses several key issues of large area thin film growth by chemical vapor deposition: structural integrity, electrostatic screening, substrate temperature control and maximal growth surface. A test reactor has been utilized to grow diamond films over /spl sim/1800 cm/sup 2/ at 13 MHz and /spl sim/1 torr pressure with 45 kW coupled power. The design is readily scalable to larger areas. To analyze the axial plasma uniformity, a two-dimensional (2-D) simulation model is presented. The electromagnetic coupling, nonequilibrium plasma chemistry and multispecies diffusion are self-consistently treated. In this 2-D approach, the slotted Faraday screen behaves as a diamagnetic medium in transmitting the magnetic field. Results are compared with experimental data for the hydrogen plasma extent, electron and gas temperatures. Neutral gas thermal conduction and hydrogen recombination dominate the energy deposition to the wall and in turn govern the plasma length. A tradeoff between quality and growth area is predicted for the reactor as the pressure is decreased.

Growth Of Diamond-Like Films On Ni Surfaces Using Remote Plasma Enhanced Chemical Vapor Deposition

Remote plasma enhanced chemical vapor deposition has been used to investigate the nucleation and growth of diamond and diamond-like films on Ni surfaces. The primary results center around hydrogen dilution experiments. Hydrogen dilution when using the polycrystalline Ni substrates tends to reduce the growth rate and increase the electrical resistivity of the films (-107 Ω-cm), it is found that at even higher hydrogen dilutions (greater than 98% H2) the films become semicontinuous with sparse and sometimes no nucleation occurring. These films, like the ones grown at lower hydrogen dilution, do not show a 1332 cm-1 diamond Raman line but show graphitic and disordered carbon features. An attempt to grow heteroepitaxial diamond on Ni(111) surfaces under conditions of high hydrogen dilution (100:1) produced a sample with oriented hillocks which are heteroepitaxially in registration with the substrate. Raman analysis showed lines characteristic of graphite and disordered carbon with an additional line at 1398 cm-1. Transmission electron microscopy produced a diffraction pattern with the lattice spacing and symmetry of epitaxial graphite with some faint polycrystalline rings.

Contamination Of Remote Plasma Processes Upon Addition Of Hydrogen As A Downstream Reagent Gas

The flexibility of the remote plasma process qualifies it as a tool for multiple step processing. Cross-contamination of remote plasma processes via interactions of reactant gasses with the chamber wall deposits has been observed when hydrogen has been introduced as a downstream reagent gas. This has been observed for both substrate cleaning prior to epitaxy and during epitaxy. With proper precautions and chamber wall conditioning, the contamination problem can he eliminated. Thus, integration of multiple remote plasma processing steps into a single chamber is possible.

Ni Substrate Processing Using In-Vacuo Wafer Transfer To Integrate Surface Characterization, Surface Cleaning, And Ni-Cu Epitaxial Alloy Growth

Due to the rapid oxidation of metal surfaces, in vacuo preparation of metal substrates is needed to provide suitable growth surfaces. Surface characterization of the metal substrates or the subsequent epitaxial metal growths must also be performed under ultrahigh vacuum conditions. Transfers of the metal samples from preparation to growth to characterization facilities must be in vacuo to protect the highly reactive surfaces. This work has been performed with an in vacuo transfer system integrating a two-stage load lock, a remote plasma enhanced chemical vapor deposition chamber, a substrate preparation facility, a metals molecular beam epitaxy chamber, and a surface analysis system. This integrated process facility will be described with particular attention to the effects of sample preparation on the subsequent metals growth. Processing with the integrated facility has resulted in the growth of epitaxial metal films, alloys, multilayers, and superlattices. Processing with only in situ wafer processing has resulted in only textured polycrystalline growths. The metals molecular beam epitaxy system of the integrated facility will be described with special emphasis on epitaxial growths of metal thin films, alloys, multilayers, and superlattices from the Cu-Ni system.

High-Resolution Transmission Electron Microscopy: An Essential Characterization Technique for Optimization of Semiconductor Epitaxy and Interfaces

High-resolution transmission electron microscopy has been utilized to critically assess semiconductor-based epitaxial films and interfaces. These results then provide a sound, scientific basis for subsequent process modification. Materials optimization is therefore achieved more efficiently.