RESEARCH PROJECTS IN MATERIAL SYNTHESIS AND PROCESSING

[Plasma Synthesis] [Combustion Synthesis] [Vapor Synthesis]

Plasma Synthesis of Materials Plasmas (both low and atmospheric pressure) can be used as a rich source of reactive radical species which can interact with surfaces to either transport condensable species (plasma deposition) or modify microstructure and composition (etching). This heterogeneous chemistry can result in the synthesis of highly valuable metastable solid phases such as diamond, the deposition of thin insulating films on silicon, or the etching of silicon to form microelectronic features . We have ongoing experimental and theoretical programs that involve the study of the basic gas-phase and surface mechanisms responsible for diamond synthesis, the synthesis and deposition of both thin film oxides, nitrides, and refractory metals, and the etching of silicon. Facilities include atmospheric pressure RF and DC arc sources, low pressure arcjets, RF and microwave glow discharges, and a spark ablation reactor. A major emphasis is on the diagnostics of the gas phase and surface during deposition on and etching, using laser-induced fluorescence and degenerate four-wave mixing spectroscopies.

Combustion Synthesis of Diamond The use of combustion sources in the synthesis of diamond is becoming increasingly more popular. Combustion synthesis provides a number of advantages over plasma technologies in the growth of diamond films. An improved understanding of the flame and heterogeneous chemistry under very fuel rich conditions will provide the basis for future reactor designs. We have ongoing experimental and theoretical programs to study diamond synthesis in low pressure flames.

Vapor Synthesis Processes in Microelectronic Device Fabrication The fabrication of microscopic features on silicon in the production of microelectronic devices requires an improved understanding of the transport and reactivity of gas-phase species in microscopic vias and trenches. In the synthesis of insulating layers such as silicon dioxide on patterned silicon, for example, or in the fabrication of metal interconnects, it is important to successfully predict the deposit profile evolution. As scale lengths in emerging technologies get smaller (<1 mm), the flow of species within such structures is essentially free molecular. We have an ongoing program that involves the detailed modeling of the transport and synthesis of thin films in such microsc opic structures. Emphasis is placed on the coupling of the transport to detailed surface chemistry, and the numerical techniques employed to accommodate a continuously evolving surface.

A list of current and recent projects in Material Synthesis and Processing along with the name of the faculty and Ph.D students involved is given here. (The last item is the name of the sponsor.)

Prof. Mark Cappelli