Microwave plasma reactors and substrates for synthetic diamond manufacture

• US 9,738,970 B2
• Filed: 09/11/2014
• Issued: 08/22/2017
• Est. Priority Date: 12/23/2010
• Status: Active Grant

• Current Assignee: Element Six (Holdings) Ltd. (Anglo American PLC)
• Original Assignee: Element Six (Holdings) Ltd. (Anglo American PLC)
• Inventors: Dodge, Carlton Nigel, Inglis, Paul Nicolas, Scarsbrook, Geoffrey Alan, Mollart, Timothy Peter, Pickles, Charles Simon James, Coe, Steven Edward, Dodson, Joseph Michael, Cullen, Alexander Lamb, Brandon, John Robert, Wort, Christopher John Howard
• Primary Examiner(s): Auer, Laura
• Application Number:
  US14/484,100
• Publication Number:
  US 20150061191A1
• Time in Patent Office: 1,076 Days
• CPC Class Codes: C01B 32/26 Preparation by using ultra-high pressure B01J3/06; by crystal growth C30B29/04
• CPC Class Codes: C23C 16/274 using microwave discharges
• CPC Class Codes: C23C 16/4586 Elements in the interior of the support, e.g. electrodes, heating or cooling devices
• CPC Class Codes: C23C 16/511 using microwave discharges
• CPC Class Codes: C23C 16/52 Controlling or regulating the coating process C23C16/45557, C23C16/279 take precedence
• CPC Class Codes: C23C 16/56 After-treatment
• CPC Class Codes: C30B 25/105 by irradiation or electric discharge
• CPC Class Codes: C30B 29/04 Diamond
• CPC Class Codes: H01J 37/32192 Microwave generated discharge H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32284 Means for controlling or selecting resonance mode
• CPC Class Codes: Y10T 428/12993 Surface feature [e.g., rough, mirror]

Abstract

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.

Claims

1. A substrate for use in a microwave plasma reactor, the substrate comprising:

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,

wherein the cylindrical disc has a diameter of 80 mm or more,

wherein the growth surface has a flatness variation no more than 100 μ

m, and

wherein the supporting surface has a flatness variation no more than 100 μ

m.

2. A substrate according to claim 1, wherein the flatness variation of the growth surface is no more than 75 μ

m, 50 μ

m, 40 μ

m, 30 μ

m, 20 μ

m, 10 μ

m, 5 μ

m, or 1 μ

m.

3. A substrate according to claim 1, wherein the flatness variation of the supporting surface is no more than 75 μ

m, 50 μ

m, 40 μ

m, 30 μ

m, 20 μ

m, 10 μ

m, 5 μ

m, or 1 μ

m.

4. A substrate according to claim 1, wherein the carbide forming refractory metal is selected from one of molybdenum, tungsten, niobium, or alloys thereof.

5. A substrate according to claim 1, wherein the cylindrical disc comprises no more than 0.5%, 0.1%, 0.075%, 0.05%, 0.025%, 0.01%, 0.005%, or 0.001% by weight of graphite forming impurities at the growth surface.

6. A substrate according to claim 1, wherein the cylindrical disc is formed of at least 99%, 99.5%, 99.9%, 99.95%, or 99.99% by weight of a carbide forming refractory metal.

7. A substrate according to claim 1, wherein the growth surface has a surface roughness R_a in the range 1 nm to 1 μ

m, 1 nm to 500 nm, 10 nm to 500 nm, 10 nm to 200 nm, 10 nm to 100 nm, 10 nm to 50 nm, 20 nm to 100 nm, or 50 nm to 100 nm.

8. A substrate according to claim 1, wherein an edge of the substrate around the growth surface is one of:

sharp;

chamfered;

or rounded.

9. A substrate according to claim 1, wherein a circular trench is provided in the growth surface separating an edge of the substrate growth surface from a central region.

10. A method of manufacturing synthetic diamond material using a chemical vapour deposition process, the method comprising:

providing a reactor configured for manufacturing synthetic diamond material;

locating a substrate according to claim 1 over a substrate holder within the reactor;

feeding process gases into the reactor; and

growing synthetic diamond material on the growth surface of the substrate,

wherein the synthetic diamond material is grown to form a polycrystalline diamond wafer having a diameter of at least 80 mm,

and wherein the polycrystalline diamond wafer is spontaneously delaminated from the substrate on cooling after the chemical vapour deposition process is completed to yield a free-standing polycrystalline diamond wafer which is substantially crack free over at least a central region thereof, wherein the central region is at least 70% of a total area of the free-standing polycrystalline diamond wafer, and wherein the central region has no cracks which intersect both external major faces of the free-standing polycrystalline diamond wafer and extend greater than 2 mm in length.

11. A method according to claim 10, wherein the central region is at least 80%, 80%, 90%, or 95% of a total area of the free-standing polycrystalline diamond wafer.

12. A method according to claim 10, wherein the polycrystalline diamond wafer has a diameter of at least 120 mm, 140 mm, 160 mm, 200 mm, or 250 mm.

13. A method according to claim 12, wherein the polycrystalline diamond wafer has a diameter no more than 400 mm or 300 mm.

14. A method according to claim 10, wherein the polycrystalline diamond wafer is grown to a thickness of at least 1.0 mm, 1.2 mm, 1.5 mm, 2.0 mm, or 2.5 mm.

15. A method according to claim 10, wherein the reactor is a microwave plasma reactor.