Element Six Gmbh

Element Six Technologies Limited

Paul Nicolas Inglis

Joseph Michael Dodson

Geoffrey Alan Scarsbrook

Christopher John Howard Wort

John Robert Brandon

Timothy Peter Mollart

Neil Perkins

Charles Simon James Pickles

Carlton Nigel Dodge

Steven Edward Coe

Alexander Lamb Cullen

Gruffudd Trefor Williams

Christopher John Kelly

Christopher John Wort

Charles Simon Pickles

The present disclosure relates to substrates for use in microwave plasma reactors. Certain substrates include a cylindrical disc of a carbide forming refractory metal having a flat growth surface on which CVD diamond is to be grown and a flat supporting surface opposed to said growth surface. The cylindrical disc may have a diameter of 80 mm or more. The growth surface may have a flatness variation no more than 100 mm The supporting surface may have a flatness variation no more than 100 mm.

Microwave plasma reactors and substrates for synthetic diamond manufacture

A method of fabricating a polycrystalline CVD synthetic diamond material having an average thermal conductivity at room temperature through a thickness of the polycrystalline CVD synthetic diamond material of at least 2000 WmK, the method comprising: loading a refractory metal substrate into a CVD reactor; locating a refractory metal guard ring around a peripheral region of the refractory metal substrate, the refractory metal guard ring defining a gap between an edge of the refractory metal substrate and the refractory metal guard ring having a width 1.5 mm to 5.0 mm; introducing microwaves into the CVD reactor at a power such that the power density in terms of power per unit area of the refractory metal substrate is in a range 2.5 to 4.5 W mm; introducing process gas into the CVD reactor wherein the process gas within the CVD reactor comprises a nitrogen concentration in a range 600 ppb to 1500 ppb calculated as molecular nitrogen N2, a carbon containing gas concentration in a range 0.5% to 3.0% by volume, and a hydrogen concentration in a range 92% to 98.5% by volume; controlling an average temperature of the refractory metal substrate to lie in a range 750&#xb0; C. to 950&#xb0; C. and to maintain a temperature difference between an edge and a centre point on the refractory metal substrate of no more than 80&#xb0; C. growing polycrystalline CVD synthetic diamond material to a thickness of at least 1.3 mm on the refractory metal substrate; and cooling the polycrystalline CVD synthetic diamond material to yield a polycrystalline CVD synthetic diamond material having a thickness of at least 1.3 mm, an average thermal conductivity at room temperature through the thickness of the polycrystalline CVD synthetic diamond material of at least 2000 WmKover at least a central area of the polycrystalline CVD synthetic diamond material, wherein the central area is at least 70% of a total area of the polycrystalline CVD synthetic diamond material, a single substitutional nitrogen concentration no more than 0.80 ppm over at least the central area of the polycrystalline CVD synthetic diamond material, and wherein the polycrystalline CVD synthetic diamond material is substantially crack free over at least the central area thereof such that the central area has no cracks which intersect both external major faces of the polycrystalline CVD synthetic diamond material and extend greater than 2 mm in length.

Thick polycrystalline synthetic diamond wafers for heat spreading applications and microwave plasma chemical vapour depositon synthesis techniques

A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapor deposition, the microwave plasma reactor comprising: a microwave generator configured to generate microwaves at a frequency f; a plasma chamber comprising a base, a top plate, and a side wall extending from said base to said top plate defining a resonance cavity for supporting a microwave resonance mode between the base and the top plate; a microwave coupling configuration for feeding microwaves from the microwave generator into the plasma chamber; a gas flow system for feeding process gases into the plasma chamber and removing them therefrom; a substrate holder disposed in the plasma chamber and comprising a supporting surface for supporting a substrate; and a substrate disposed on the supporting surface, the substrate having a growth surface on which the synthetic diamond material is to be deposited in use, wherein the substrate dimensions and location within the resonance cavity are selected to generate a localized axisymmetric Eelectric field profile across the growth surface in use, the localized axisymmetric Eelectric field profile comprising a substantially flat central portion bound by a ring of higher electric field, the substantially flat central portion extending over at least 60% of an area of the growth surface of the substrate and having an Eelectric field variation of no more than &#xb1;10% of a central Eelectric field strength, the ring of higher electric field being disposed around the central portion and having a peak Eelectric field strength in a range 10% to 50% higher than the central Eelectric field strength.

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Ascot, United Kingdom

Paul Nicolas Inglis