The Preparation And Research On Large Area Diamond Thick Films Deposited By Hot Filament Chemical Vapor Deposition

The artificial diamond films have great use value in production, and plays very importantrole in aspects of mechanism, thermology, optics, or semiconductor, acoustics and modernmilitary affairs.The large area diamond thick films of hot filament chemical vapor deposition (HFCVD)is new type of product developing on the basis of CVD diamond thin films. It has receivedgreat attention because it has higher growth efficiency, better use performance as one kind ofcutting tool, and stronger market competition ability.This paper applies HFCVD method to produce large area diamond thick films, studiesand discusses systematically from the aspects of design and alteration of equipments,technique methods, and the form mechanism of diamond thick films and the effect factors ofits quality.1. We enlarge the size of equipment on the basis of early small equipment of diamondthin films, alternate the previous single-coil filament with large area temper filament grid;change the base and enable it to rotate when working; change the tungsten filament withtungsten surrounding tantalum wire, improve the working temperature of filament fromprevious2300℃to2600℃needed in experiments; and increase pulsed plasma, accelerate thedissociation of hydrogen molecule into hydrogen atom greatly; improve the air flow system,and propose precise flow of complete technique of experiment.2. With study and discussion on the growth rate and quality of diamond films, we findthe carbon hydrogen rate of gas of input system has an optimum value under a certainfilament temperature, for example, when the filament temperature is2600℃, and the carbonhydrogen rate of input gas is about10.6%.3. Under the same filament temperature2000℃, the growth rate and quality of diamondfilms produced under different substrate temperatures are different markedly. When thesubstrate temperature is improved from850℃to950℃, the growth rate and quality ofdiamond advance greatly.4. This paper discusses the important role of hydrogen atom in growth of diamond filmsand earlier substance of diamond growth deeply on the basis of theoretical studies includingdiamond structure, bond energy of carbon atom, base point energy and environment effect andother aspects.