MICROWAVE PLASMA REACTOR FOR MANUFACTURING SYNTHETIC DIAMOND MATERIAL

• US 20150030786A1
• Filed: 12/14/2011
• Published: 01/29/2015
• Est. Priority Date: 12/23/2010
• Status: Active Grant

• Current Assignee: Element Six Technologies US Corporation (Anglo American PLC)
• Original Assignee: Element Six (Holdings) Ltd. (Anglo American PLC)
• Inventors: Coe, Steven Edward, Wilman, Jonathan James, Twitchen, Daniel James, Scarsbrook, Geoffrey Alan, Brandon, John Robert, Wort, Christopher John Howard
• Granted Patent: US 11,371,147 B2
• Time in Patent Office: Days
• US Class Current: 427/575
• CPC Class Codes: C23C 16/274 using microwave discharges
• CPC Class Codes: C23C 16/45504 Laminar flow
• CPC Class Codes: C23C 16/45563 Gas nozzles
• CPC Class Codes: C23C 16/45565 Shower nozzles
• CPC Class Codes: C23C 16/511 using microwave discharges
• CPC Class Codes: C30B 25/105 by irradiation or electric discharge
• CPC Class Codes: C30B 29/04 Diamond
• CPC Class Codes: H01J 37/32 Gas-filled discharge tubes heating by discharge H05B
• CPC Class Codes: H01J 37/32192 Microwave generated discharge H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32238 Windows
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32449 Gas control, e.g. control of the gas flow

Abstract

A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapour deposition, the microwave plasma reactor comprising: a plasma chamber; a substrate holder disposed in the plasma chamber for supporting a substrate on which the synthetic diamond material is to be deposited in use; a microwave coupling configuration for feeding microwaves from a microwave generator into the plasma chamber; and a gas flow system for feeding process gases into the plasma chamber and removing them therefrom; wherein the gas flow system comprises a gas inlet nozzle array comprising a plurality of gas inlet nozzles disposed opposite the substrate holder for directing process gases towards the substrate holder, the gas inlet nozzle array comprising: at least six gas inlet nozzles disposed in a substantially parallel or divergent orientation relative to a central axis of the plasma chamber; a gas inlet nozzle number density equal to or greater than 0.1 nozzles/cm², wherein the gas inlet nozzle number density is measured by projecting the nozzles onto a plane whose normal lies parallel to the central axis of the plasma chamber and measuring the gas inlet number density on said plane; and a nozzle area ratio of equal to or greater than 10, wherein the nozzle area ratio is measured by projecting the nozzles onto a plane whose normal lies parallel to the central axis of the plasma chamber, measuring the total area of the gas inlet nozzle area on said plane, dividing by the total number of nozzles to give an area associated with each nozzle, and dividing the area associated with each nozzle by an actual area of each nozzle.

Claims

1. A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapour deposition, the microwave plasma reactor comprising:

a plasma chamber;

a substrate holder disposed in the plasma chamber for supporting a substrate on which the synthetic diamond material is to be deposited in use;

a microwave coupling configuration for feeding microwaves from a microwave generator into the plasma chamber; and

a gas flow system for feeding process gases into the plasma chamber and removing them therefrom;

wherein the gas flow system comprises a gas inlet nozzle array comprising a plurality of gas inlet nozzles disposed opposite the substrate holder for directing process gases towards the substrate holder, the gas inlet nozzle array comprising;

at least six gas inlet nozzles disposed in a substantially parallel or divergent orientation relative to a central axis of the plasma chamber;

a gas inlet nozzle number density equal to or greater than 0.1 nozzles/cm², wherein the gas inlet nozzle number density is measured by projecting the nozzles onto a plane whose normal lies parallel to the central axis of the plasma chamber and measuring the gas inlet number density on said plane; and

a nozzle area ratio of equal to or greater than 10, wherein the nozzle area ratio is measured by projecting the nozzles onto a plane whose normal lies parallel to the central axis of the plasma chamber, measuring the total area of the gas inlet nozzle area on said plane, dividing by the total number of nozzles to give an area associated with each nozzle, and dividing the area associated with each nozzle by an actual area of each nozzle,

wherein the gas inlet nozzle number density and the nozzle area ratio are calculated over at least 50% of all the gas inlet nozzles in the gas inlet nozzle array.

2. A microwave plasma reactor according to claim 1, wherein the gas inlet nozzle number density is equal to or greater than 10 nozzles/cm².

3. A microwave plasma reactor according to claim 1, wherein the gas inlet nozzle number density is equal to or less than 100, 50, or 10 nozzles/cm².

4. A microwave plasma reactor according to claim 1, wherein the nozzle area ratio is equal to or greater than 30, 100, 300, 1000, or 3000.

5. A microwave plasma reactor according to claim 1, wherein the nozzle area ratio is equal to or less than 100000, 30000, or 10000.

6. A microwave plasma reactor according to claim 1, wherein the gas inlet nozzle array comprises equal to or greater than 7, 9, 10, 15, 20, 30, 40, 60, 90, 120, 150, 200, 300, 500, 700, 1000, 1200, 1500 gas inlet nozzles.

7. A microwave plasma reactor according to claim 1, wherein each gas inlet nozzle has an outlet diameter in the range 0.1 mm to 5 mm, 0.2 mm to 3.0 mm, 2.0 mm to 3 mm, 0.2 mm to 2 mm, 0.25 mm to 2 mm, or 0.25 mm to 1.5 mm.

8. A microwave plasma reactor according to claim 1, wherein a ratio of total nozzle area/area of the gas inlet nozzle array is equal to or less than 0.5, 0.35, 0.3, 0.2, 0.1, 0.05, 0.02, 0.01, or 0.007.

9. A microwave plasma reactor according to claim 1, wherein a total area of nozzles in the gas inlet nozzle array, given in mm², is in a range 1 to 5000, 5 to 3000, 10 to 3000, 20 to 2750, 30 to 2750, or 50 to 2700.

10. A microwave plasma reactor according to claim 1, wherein a total area of the gas inlet nozzle array over which the gas inlet nozzles are spaced, given in mm², is in a range 100 to 15000, 200 to 15000, 400 to 10000, 800 to 10000, or 1000 to 8000.

17. A microwave plasma reactor according to claim 1, wherein a minimum distance D_c between the gas inlet nozzle array and the substrate holder is less than or equal to 6R_s, 4R_s, or 2R_s, where R_s is a radius of the substrate holder.

18. A microwave plasma reactor according to claim 1, wherein a maximum radius of the gas inlet nozzle array R_m meets the criteria:

R_m×

F_m is greater than or equal to R_s, where R_s is a radius of the substrate holder and Fm is equal to or greater than 0.5, 0.6, 0.7, 0.8, 0.9, or 1 and equal to or less than 1.5, 1.3, 1.2, or 1.1.

19. A microwave plasma reactor according to claim 1, wherein each gas inlet nozzle has an inlet portion having a first diameter and an outlet portion having a second diameter, the first diameter being larger than the second diameter.

20. A microwave plasma reactor according to claim 1, wherein the microwave coupling configuration for feeding microwaves from the microwave generator into the plasma chamber is disposed at an end of the plasma chamber upstream of the substrate holder, wherein the gas inlet array is disposed in a central region of said end and the microwave coupling configuration comprises a microwave window disposed in a ring around the gas inlet array.

27. A method of manufacturing synthetic diamond material using the microwave plasma reactor according to claim 1, the method comprising:

injecting process gases into the plasma chamber through the plurality of gas inlet nozzles;

feeding microwaves from a microwave generator into the plasma chamber through the microwave coupling configuration to form a plasma above a substrate disposed over the substrate holder; and

growing synthetic diamond material on a growth surface of the substrate.

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