Microwave plasma reactor for manufacturing synthetic diamond material

Patent metadata

Field	Value
Publication number	US-10403477-B2
Application number	US-201113994880-A
Country	US
Kind code	B2
Filing date	Dec 14, 2011
Priority date	Dec 23, 2010
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

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, wherein the resonance cavity has a central rotational axis of symmetry extending from the base to the top plate, and wherein the top plate is mounted across said central rotational axis of symmetry; 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; and a substrate holder disposed in the plasma chamber and comprising a supporting surface for supporting a substrate on which the synthetic diamond material is to be deposited in use; wherein the resonance cavity is configured to have a height, as measured from the base to the top plate of the plasma chamber, which supports a TM011 resonant mode between the base and the top plate at said frequency f, and wherein the resonance cavity is further configured to have a diameter, as measured at a height less than 50% of the height of the resonance cavity as measured from the base, which satisfies the condition that a ratio of the resonance cavity height/the resonance cavity diameter is in the range 0.3 to 1.0.

First claim

The invention claimed is:

1. A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapor deposition, the microwave plasma reactor comprising:
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, wherein the resonance cavity has a central rotational axis of symmetry extending from the base to the top plate, and wherein the top plate is mounted across said central rotational axis of symmetry;
a microwave coupling configuration for feeding microwaves from a microwave generator into the plasma chamber;
a gas flow system for feeding synthetic diamond material process gases into the plasma chamber and removing them therefrom; and
a substrate holder disposed in the plasma chamber and comprising a supporting surface for supporting a substrate on which the synthetic diamond material is to be deposited in use;
wherein the resonance cavity is configured to have a height, as measured from the base to the top plate of the plasma chamber, which supports a TM011 resonant mode between the base and the top plate at a frequency in the range 400 to 500 MHz, 800 to 1000 MHz, or 2300 MHz to 2600 Mz,
wherein the resonance cavity is further configured to have a diameter, as measured at a height less than 50% of the height of the resonance cavity as measured from the base, which satisfies the condition that a ratio of the resonance cavity height/the resonance cavity diameter is in the range 0.3 to 1.0,
wherein the resonance cavity comprises internal walls configured to be exposed to a plasma formed within the resonance cavity in use, said internal walls comprising metallic surfaces forming at least 75% of a total surface area of said internal walls within the resonance cavity,
wherein a portion of said internal walls is formed by an annular dielectric window, formed in one or several sections, said annular dielectric window forming no more than 25% of the total surface area of the internal walls within the resonance cavity; and
wherein the plasma chamber does not contain a quartz process gas confinement element,
and wherein the annular dielectric window is positioned such that microwaves are coupled into the plasma chamber in a direction parallel to the central rotational axis.

2. A microwave plasma reactor according to claim 1 , wherein the ratio of the resonance cavity height/the resonance cavity diameter is in the range 0.4 to 0.9 or 0.5 to 0.8.

3. A microwave plasma reactor according to claim 1 , wherein the resonance cavity height, as measured from the base to the top plate of the plasma chamber, is in a range:
300 mm to 600 mm, 300 mm to 500 mm, or 400 mm to 500 mm at a microwave frequency fin the range 400 MHz to 500 MHz;
150 mm to 300 mm, 150 mm to 250 mm, or 200 mm to 250 mm at a microwave frequency fin the range 800 MHz to 1000 MHz; or
50 mm to 110 mm, 50 mm to 90 mm, or 70 mm to 90 mm at a microwave frequency fin the range 2300 MHz to 2600 MHz.

4. A microwave plasma reactor according to claim 1 , wherein the resonance cavity diameter is in the range:
400 mm to 1000 mm, 500 mm to 900 mm, or 600 mm to 800 mm at a microwave frequency fin the range 400 MHz to 500 MHz;
200 mm to 500 mm, 250 mm to 450 mm, or 300 mm to 400 mm at a microwave frequency fin the range 800 MHz to 1000 MHz; or
70 mm to 180 mm, 90 mm to 160 mm, or 110 mm to 150 mm at a microwave frequency fin the range 2300 MHz to 2600 MHz.

5. A microwave plasma reactor according to claim 1 , wherein the resonance cavity has a volume in a range:
0.018 m 3 to 0.530 m 3 , 0.062 m 3 to 0.350 m 3 , 0.089 m 3 to 0.270 m 3 , or 0.133 m 3 to 0.221 m 3 at a microwave frequency fin the range 400 to 500 MHz;
0.002 m 3 to 0.06 m 3 , 0.007 m 3 to 0.04 m 3 , 0.01 m 3 to 0.03 m 3 , or 0.015 m 3 to 0.025 m 3 at a microwave frequency fin the range 800 MHz to 1000 MHz; or
9.8×10 −5 m 3 to 2.9×10 −3 m 3 , 3.4×10 −4 m 3 to 1.96×10 −3 m 3 , 4.9×10 −4 m 3 to 1.47×10 −3 m 3 , or 7.35×10 −4 m 3 to 1.23×10 −3 m 3 at a microwave frequency fin the range 2300 to 2600 MHz.

6. A microwave plasma reactor according to claim 1 , wherein the resonance cavity is cylindrical.

7. A microwave plasma reactor according to claim 1 , wherein an upper portion of the resonance cavity has a larger diameter than a lower portion of the resonance cavity, the upper portion of the resonance cavity being configured to support at least one secondary microwave mode which at least partially eliminates a high electric-field anti-node in the upper portion of the resonance cavity in use.

8. A microwave plasma reactor according to claim 7 , wherein a ratio of a lower diameter/an upper diameter of the resonance cavity is greater than 0.4 and less than 1, wherein the lower diameter is measured at a height less than 50% of the height of the resonance cavity as measured from the base and the upper diameter is measured at a height greater than 50% of the height of the resonance cavity as measured from the base.

9. A microwave plasma reactor according to claim 8 , wherein said ratio is in a range 0.5 to 0.9, 0.6 to 0.9, or 0.7 to 0.8.

10. A microwave plasma reactor according to claim 8 , wherein:
at a microwave frequency fin the range 400 to 500 MHz the lower diameter lies in a range 400 mm to 900 mm, 500 mm to 900 mm, 600 mm to 800 mm, or 650 mm to 800 mm, and the upper diameter may lie in a range 600 mm to 1000 mm, 700 mm to 1000 mm, 700 mm to 900 mm, or 800 mm to 900 mm;
at a microwave frequency fin the range 800 MHz to 1000 MHz the lower diameter lies in a range 200 mm to 450 mm, 250 mm to 450 mm, 300 mm to 400 mm, or 330 mm to 400 mm, and the upper diameter lies in a range 300 mm to 500 mm, 350 mm to 500 mm, 350 mm to 450 mm, or 400 mm to 450 mm; or
at a microwave frequency fin the range 2300 to 2600 MHz the lower diameter lies in a range 70 mm to 160 mm, 90 mm to 160 mm, 100 mm to 150 mm, or 120 mm to 150 mm, and the upper diameter may lie in a range 100 mm to 200 mm, 120 mm to 200 mm, 130 mm to 170 mm, or 150 mm to 170 mm.

11. A microwave plasma reactor according to claim 1 , wherein the metallic surfaces of the internal walls of the resonance cavity form at least 75%, 80%, 85%, 90% or 95% of a total surface area of said internal walls within the resonance cavity.

12. A microwave plasma reactor according to claim 11 , wherein said metallic surfaces are made of aluminium or an alloy thereof comprising at least 80%, 90%, 95%, or 98% by weight of aluminium.

13. A microwave plasma reactor according to claim 11 , wherein the annular dielectric window forms no more than 25%, 20%, 15%, 10%, or 5% of the total surface area of the internal walls within the resonance cavity.

14. A microwave plasma reactor according to claim 1 , wherein the microwave plasma reactor further comprises an electrically conductive surface located within the plasma chamber over a high electric field anti-node region which would exist in a corresponding plasma chamber which did not comprise the conductive surface.

15. A microwave plasma reactor according to claim 14 , wherein the conductive surface is cone-shaped.

16. A microwave plasma reactor according to claim 15 , wherein the cone-shaped conductive surface comprises a rounded tip.

17. A microwave plasma reactor according to claim 15 , wherein the cone-shaped conductive surface forms an annular recess in the plasma chamber and the annular dielectric window is disposed in said recess.

Assignees

• Brandon John Robert
• Cullen Alexander Lamb
• Williams Stephen David
• Dodson Joseph Michael
• Wilman Helen
• Wort Christopher John Howard
• Element Six Tech Ltd

Inventors

• Brandon John Robert
• Cullen Alexander Lamb
• Williams Stephen David
• Dodson Joseph Michael
• Wilman Jonathan James
• Wort Christopher John Howard

Classifications

• H01J37/32458 Primary

  Vessel · CPC title

• H01J37/32284

  Means for controlling or selecting resonance mode · CPC title

• C23C16/511

  using microwave discharges · CPC title

• C23C16/274 Primary

  using microwave discharges · CPC title

• H01J37/32192

  Microwave generated discharge (H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence) · CPC title