Title of Invention

ULTRAHARD DIAMONDS AND METHOD OF MAKING THEREOF

Abstract A single Crystal diamond grown by microwave plasma chemical vapor deposition an-nealed at pressuer in excess of 4.0 GPa and healed to temparature in excess or 1500 degrees C that has a hardness of greater than 120GPa.A method for monufacture a hard single crystal diamond includes growing a single crystal diamond and annealing the single crystal diamond at pressures in excess of 4.0 GPa and a temperature in excess of 1500 degrees C to have a hardness in excess of 120 GPa.
Full Text WO 2005/007936 PCT/US2004/022611
[0001] The present invention claims the benefit of Provisional Application No.
60/486,435 filed on July 14, 2003, which is hereby incorporated by reference.
Statement of Government Interest
[0002] This invention was made with U.S. government support under grant number
EAR-0135626 from the National Science Foundation. The U .S. government has certain
rights in the invention.
BACKGROUND OF THE INVENTION
Field of the Invention
[0003] The present invention relates to diamonds, and more particularly, to an
ultrahard diamond produced using a Microwave Plasma Chemical Vapor Deposition.
(MFC VD) within a deposition chamber-
Description of Related Art
[0004] Large-scale production of synthetic diamond has long been an objective of both
research and industry. Diamond, in addition to its gem properties:, is the hardest known
material, has the highest known thermal conductivity, and is transparent to a wide variety
of electromagnetic radiation. Thus, diamond is valuable because of its wide range of
applications in a number of industries, in addition to its value as a gemstone.
[0005] For at least the last twenty years, a process of producing small quantities of
diamond by chemical vapor deposition (CVD) has been available. As reported by B. V.
Spitsyn et aL in "Vapor Growth of Diamond on Diamond and Other Surfaces," Journal of
Crystal Growth, vol. 52, pp. 219-226, the process involves CVD of diamond on a
substrate by using a combination of methane, or another simple hydrocarbon gas, and
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WO 2005/007936 PCT/US2004/022611
hydrogen gas at reduced pressures and temperatures of 800-1200° C. The inclusion of
hydrogen gas prevents the formation of graphite as the diamond nucleates and grows.
Growth rates of up to 1 µm/hour have been reported with this technique,
[0006] Subsequent work, for example, that of Kamo et al. as reported in "Diamond
Synthesis from Gas Phase in Microwave Plasma," Journal of Crystal Growth, vol. 62, pp.
642-644, demonstrated the use of Microwave Plasma Chemical Vapor Deposition
(MPCVD) to produce diamond at pressures of 1-8 Kpa in temperatures of 800-1000º C
with microwave. power of 300-700 W at a frequency of 2.45 GHz. A concentration of 1 -3
% methane gas was used in the process of Kamo et al. Maximum. growth rates of 3 µm/hour
have been reported using this MPCVD process.
[0007] Natural diamonds have a hardness between 80-120 GPa Most grown or
manufactured diamonds, regardless of the process, have a hardness of less than 110 GPa.
Other than type IIa natural diamonds which have been annealed, diamonds have not been
reported to have a hardness of greater than 120 GPa.
SUMMARY OF THE INVENTION
[0008] Accordingly, the present invention is directed to a. an apparatus and a. method
for producing diamond that substantially obviates one or more of the problems due to
limitations and disadvantages of the related art.
[0009] An object of the present invention, relates to an apparatus and method for
producing diamond in a microwave plasma chemical vapor deposition system having
increased hardness.
[0010] Another object of the present invention is to enhance the optical characteristics
of a single crystal diamond,
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[0011] Additional features and advantages of the invention will be set forth in the
description which follows, and in part will be apparent from the description, or may be
learned by practice of the invention. The objectives and other advantages of the
invention will be realized and attained by the structure particularly pointed out in the
written description and claims hereof as well as the appended drawings.
[0012] To achieve these and other advantages and in accordance with the purpose of
the present invention, as embodied and broadly described, a single crystal diamond
growth by microwave plasma chemical vapor depositiion annealed at pressures in excess
of 4.0 GPa and heated to temperature in excess of 1500 degrees C that has a hardness of
greater than 120 GPa.
[0013] In another embodiment, A single crystal diamond having a hardness of 160-180
GPa.
[0014] In accordance with another embodiment of the present invention, A method for
manufacture a. hard single crystal diamond includes growing a single crystal diamond and
annealing the single crystal diamond at pressures in excess of 4.0 GPa and a temperature
in excess of 1500 degrees C to have a hardness in excess of 120 GPa,
[0015] It is to be understood that both the foregoing general description and the
following detailed description are exemplary and explanatory and are intended to provide
further explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The accompanying drawings, which are included to provide a further
understanding of the invention and are incorporated in and constitute a part of this
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specification, illustrate embodiments of the invention and together with the description
serve to explain the principles of the invention.
[0017] FIG. 1 is a diagram of an indenter for testing the hardness of a diamond.
[0018] FIG, 2 is a picture of an indentation made on a diamond,
[0019] FIG- 3 is a graph showing the hardness and toughness of annealed microwave
plasma CVD-grown single-cryslal diamonds in comparison to type Ha natural diamonds
annealed type Ua natural diamonds, annealed type Ia natural diamonds and annealed type
Ib HPHT synthetic diamonds,
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] Reference will now be made in detail to the preferred embodiments of the
present invention, the results of which, are illustrated in the accompanying drawings
[0021] The microwave plasma CVD'growm single-crystal diamond referred to in this
application were grown with the apparatus described in U.S. patent application number
10/288,499 filed on November 6, 2002 entitled "Apparatus and Method for Diamond
Production," which is here by incorporated by reference. In general, a seed diamond is
placed in holder that moves the seed diamond/grown diamond as the diamond is grown.
The inventors of this application ate also inventors in U.S. patent application number
10/288,499
[0022] A microwave plasma CVD-grown single-crystal diamond having a thickness of
greater than 1 millimeter was deposited on type Ib {100} synthetic diamond. In order to
enhance the growth rate (50-150 µm/h) and promote smooth {100} face growth, single-
crystal diamonds ware grown in an atmosphere of N2/CH4 = 0.2-5.0%, CH4H2= 12-
20%, 120-220 torr total pressure and 900-1500 °C from a microwave indtuced plasma
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within a CVD chamber. Raman spectra show a small amount of hydiogenated
amorphous carbon (a-C:H)4 and nitrogen-containing a-C:H (Na-C:H)4 giving rise to
brown diamond at 1400 °C. Photoluminescence (PL) spectra indicate
nitrogen-vacancy (N-V) impurities. Single crystal diamonds up to 4.5 mm in thickness
have been fabricated at growth rates that are as much as two orders of magnitude higher
than conventional poly crystalline CVD growth methods.
[0023] The microwave plasma CVD-grown single-crystal diamonds were annealed at
pressures in excess of 4.0 GPa, such as 5-7 GPa, and heated to temperature in excess of
1500 degrees C, such as 1800-2900 degrees C, for 1-60 min in a reaction vessel using a
belt-type or anvil-type apparatus- The reaction vessel can be a cell, such as that
described in U.S. Pat, Nos. 3,745,623 or 3,913,280, which are hereby incorporated by
reference. Such an annealing treatment, reduces or eliminates the color in the microwave
plasma CVD-grown single-crystal diamond crystals, and lightening the tint of the type Ib
HPHT synthetic seed crystals. Further, the hardness of the annealed microwave plasma
CVD-grown single-crystal diamond annealed CVD diamond (at least -140 GPa) is
beyond that of annealed or unannealed type Ib HPHT synthetic diamond (~90 GPa),
annealed type Ia natural diamond ('-100 GPa), type II a natural diamond (-110 GPa),
and annealed type IIa natural diamond (-140 GPa) and sintered polycrystalline
diamond (120-140 GPa).
[0024] EXAMPLE #1
A single crystal CVD diamond was grown with a N2/CH4 ratio of 5% at a
temperature of approximately 1500 degrees C on a yellow type Ib HPHT synthetic

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diamond in a microwave CVD chamber. The dimension, of the microwave plasmaCVD-
grown single-crystal diamond was onec centimeter square and a little larger than one
millimeter in thickness. The color of the microwave plasma CVD-grown single-crystal
diamond was brown. The brown microwave plasma CVD-grown single'crystal diamond
on the type Ib HPHT synthetic seed diamond was then placed as a sample in the reaction
vessel.
[0025] The reaction'vessel '■was placed in a conventional HPHT apparatus, First, the
pressure was increased to a pressure of 5.0 GPa, and then the temperature was brought up
to 2200 degrees C. The sample was maintained at these annealing conditions for five
minutes, and then the temperature was decreased over a period of about one minute to
room temperature before the pressure was released.
[0026] The sample was removed from the reaction vessel and examined under an
optical microscope. The brown microwave plasma CVD-grown single-crystal diamond
had turned to a light green translucent color and remained firmly bonded to the yellow
type Ib HPHT synthetic diamond, The yellow COLOR of the type Ib HPHT synthetic
diamond became a. lighter yellow or a more translucent yellow. The bardness was about
160 GPa,
[0027] EXAMPLE #2
Same as example #1 abovet except the annealing conditions were maintained for 1
hour. The brown microwave plasma CVP-grown single-crystal diamond turned to a light
green color, which was more translucent than the light green color resulting in example #1,
and remained firmly bonded to the type Ib HPHT synthetic diamond. The yellow color of the
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WO 2005/007936 PCT/US2004/0226110
type Ib HPHT synthetic diamond became a lighter yellow or a more translucent yellow. The
hardness was about 180 GPa.
[0028] EXAMPLE #3
A single crystal CVD diamond was grown with a N2/CH4 ratio of 5% at a temperature
of approximately 1450 degrees C on a yellow type Ib HPHT synthetic diamond in a
microwave CVD chamber. The dimension of the microwave plasma CVD-grown single-
crystal diamond was one centimeter square and a little larger than one millimeter in thick.
The color of the microwave plasma CVD-grown single-crystal diamond was a light brown or
yellow. In other words, a yellow or light brown that was not as dark as the brown of the
microwave plasma CVD-grown single-crystal diamond in example #1 above. The yellow or
light brown microwave plasma CVD-grown single-crystal diamond on the type Ib HPHT
synthetic diamond was then placed as a sample in a reaction vessel. The hardness was greater
than 160 GPa.
[0029] The reaction vessel was placed in a conventional HPHT apparatus. The
pressure was increased to about to a pressure of 5.0 GPa, and then the temperature was
rapidly brought up to about 2000 degrees C. The sample was maintained at these
annealing conditions for five minutes, and then the temperature was decreased over a
period of about one minute to room temperature before the pressure was released,
[0030] The sample was removed from, the reaction vessel, and examined under an
optical microscope. The Light brown microwave plasma CVD-grown single-crystal
diamond had. become colorless and remained firmly bonded to the yellow type Ib HPHT
synthetic diamond- The yellow color of the type Ib HPHT synthetic diamond also
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became a lighter yellow or a more translucent yellow,
[0031] EXAMPLE #4
Same as example #1 except a colorless microwave plasma single-crystal CVD-grown
diamond in an atmosphere of N2/CH4 = 5% at a temperature of -1200 degree C was annealed.
After annealing, the microwave plasma single-crystal CVD-grown diamond was blue. This
blue microwave plasma single-crystal CVD-grown diamond had a very high toughness of >20
MPa m1/2. The hardness was shout ~140'GPa-
[0032] EXAMPLE #5
Same as example #1 except a colorless microwave plasma single-crystal CVD-grown
diamond in an atmosphere of N2/CH4 ~ ,5% at a temperture of-1200 degree C was
annealed. The microwave plasma single-crystal CVD-grown diamond was still colorless.
This colorless microwave plasma single-crystal CVD-grown diamond had a hardness of
-160 GPa and toughness of -10 MPa m1/2.
[0033] FIG. 1 is a diagram of an indenter for testing the hardness of a diamond., A
Vickers hardness test were performed on the annealed microwave plasma CVD-grown
single-crystal diamonds with the indenter 1 shown in FIG. 1 Theinvention 1 inFig.1has
an impinging material 2 positioned on a mount 3. The impinging material 2 can be
silicon carbide, diamond or some other hard material. The impinging material has a face
with a pyramidal Vickers indenter shape in "which the sides of the pyramidal Vickers
indenter shape have an angle of 136*.
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WO 2005/007936 PCT/US2004/0226110
[0034] The indenter applies a point load to the test diamond 2 until an indentation or
crack is formed in the test diamond 2. To prevent elastic deformation of the indenter, the
loads were varied from 1 to 3 kg on {100} faces in the direction of the test
diamonds. Dimensions of the indentation and the cracks associate with the indentation
are measured via optical microscopy. FIG. 2 is a picture of an indentation made on a
microwave plasma CVD-grown single-crystal diamond.
[0035] By measuring the length D and height h of the indentation, the hardness Hv of
the test diamond can be determined from the following equation (1)■
(1):HV=1.854XP/D2
P is the maximum load used on the indenter to form an indentation into the test diamond.
D is the length of the longest crack formed by the indenter in the test diamond andh h is
the depth of the indentation into the test diamond, as shown in FIG. 1.
[0036] The fracture toughness Kc of the test diamond can be determined by using the
hardness Hv from equation (1) in the following equation (2):
(2): Kc = (0.016±0.004)(E/Hv)l/2(P/C3/2)
E is the Young's modulus, which is assumed to be 1000 GPa. Pis the maximum load
used on the indenter to form the indentation into the test diamond. The term d is the
average length of the indentation cavity in the test diamond, as shown in FIG, 2 such that
d = (d1+d2)/2. The term c is -the average length of the radial cracks in the test diamond,
as shown in FIG, 2 such the c= (c1+c2)/2
[0037] Because of the uncertainties in determining hardness, identical measurements
were also performed on other diamonds. The measurements on other diamonds were
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WO 2005/007936 PCT/US2004/0226110
found to be in agreement with published data oil the other diamonds. The Vickers
bardness tests were done on the (,100) faces of the various types of diamonds in the (100)
direction.
[0038] The indented surfaces of the annealed microwave plasma CVD-grown single-
crystal diamonds as viewed by optical microscopy clearly differ from those of other
(softer) diamonds. The annealed microwave plasma CVD-grown single-cryatal diamond
exhibits square crack patterns along. or , no cross-like cracked lines along
, and a water-print-like deformation mark was produced on the surface of the
annealed microwave plasma CVD-grown single-crystal diamond by the pyramidal
Vickers indenter. In contrast, an annealed type IIa natural diamond has less square crack
patterns along (110) and (111) but still exhibits the cross-like (100) cracks of softer
diamonds. Such results indicate that annealed microwave plasma CVD-grown single-
crystal diamond is harder than the indenter, and the pressure due to plastic deformation
of the indenter causes slippage of the softer {111} faces.
[0039] The Vickers indenters typically cracked after -15 measurements on unannealed
microwave plasma CVD-grown single-crystal diamonds and type Ib natural diamonds.
Further, The Vickers indenters typically cracked after -5 measurements on annealed type
IIa natural diamonds, annealed type Ia natural diamonds and annealed type Ib HPHT
synthetic diamonds. However, the Vickers indenter cracked after only one or two
measurements on the amealed microwave plasma CVD-grown single-crystal diamonds.
These observations further indicate that th.e annealed microwave plasma CVD-grown
single-crystal diamonds are harder than the measured values indicate. Indeed, many
annealed microwave plasma CVD-grown single-crystal diamonds simply damaged the
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softer indenter. In such instances, the indentex Left no imprint whatsoever the
surface of the annealed microwave plasma CVD-grown single-crystal diamonds.
[0040] FIG. 3 is a graph showing the hardness and toughness of annealed microwave
plasma CVD-grown single-crystal diamonds in comparison to type IIa natural diamonds
annealed type IIa natural diamonds, annealed type Ia natural diamonds and annealed type
Ib HPHT synthetic diamonds. As shown in FIG, 3, the annexed microwave plasma.
CVD-grown single-crystal diamonds have much higher hardness than type IIa natural
diamond, as shown by the dotted square 10 in FIG. 3. All of the annealed microwave
plasma CVD-grown single-crystal diamonds also have a higher hardness than the
reported range the reported range of hardness for polyerystalline CVD diamonds, shown
by the dotted square 20 in FIG. 3. The microwave plasma CVD-grown single-crystal
diamonds represented in FIG. 3 have a fracture toughness of 6-10 MPa m1/2 with a
hardness of 140-180 GPa with indications that they may be harder.
[0041] As the present invention may be embodied in several forms without departing
from the spirit or essential characteristics thereof, it should also be understood that the
above-described embodiments ate not limited by any of the details of the foregoing
description, unless otherwise specified, but rather should be construed broadly within its
spirit and scope as defined in the appended claims, and therefore all changes and
modifications that fall within the metes and bounds of the claims,or equivalence of such
metes and bounds are therefore intended to be embraced by the appended claims.
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WO 2005/007936 PCT/US2004/0226110
What is claimed is:
1. A single crystal diamond grown by microwave plasma chemical vapor deposition
annealed at pressures in excess of 4.0 GPa and heated to temperature in escess of 1500
degrees C that has a hardness of greater than 120 GPa.
2. The single crystal diamond of claim 1, wherein the fracture toughness is 6-10 MPa
m12 .
3. The single crystal diamond of claim 1, wherein the hardness Is 160-180 GPa
4. The single crystal diamond of claim 1, wherein hardness is determined by the
equation of H— 1,854xP/D2 in which P is the maximum load used on the indenter to form an.
indentation into the single crystal diamond and D is the length of the longest crack formed by
the indeater in the single crystal diamond and h is the depth of the indentation into the single
crystal diamond
5. The single crystal diamond of claim 3 having a fracture toughness of 6-10 Mpa
m1/2
6. A single crystal diamond having a hardness of 160-180 GPa.
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WO 2005/007936 PCT/US2004/0226110
7. The single crystal diamond of claim 6 having a fracture toughness of 6-10 Mpa
m1/2
8. The single crystal diamond of claim 6, wherein hardness is determined by the
equation of Hv - 1 .854xP/D2 in which P is the maximum load used on the indenter to form an
indentation into the single crystal diamond and D is the length of the longest crack formed by
the indenter in the single crystal diamond and h is the depth of the indentation into the single
crystal diamond,
9 . A method for manufacture a hard single crystal diamond comprising:
growing a single crystal diamond; and
annealing the single crystal diamond at pressures in excess of 4.0 GPa and a
temperature in excess of 1500 degrees C to have a hardness in excess of 120 GPa.
10. The method of claim 9,whereing growing single crystal diamond includes
microwave plasma chemical vapor deposition-
11. The method of claim 9, wherein growing single crystal diamond occurs in an
atmosphere of N2/CH4 = 0.2-5.0% and CH4/H2 = 12-20% at a total pressure of 120-220 ton,
12. The method of claim 9, whetein annealing the single crystal diamond results in a
single crystal diamond having a hardness in excess of 160-180 GPa
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WO 2005/007936 PCT/US2004/0226110
13. The method of claim 9, wherein growiog single crystal diamond occurs in an
atmosphere having a temperture of 900-1500 degrees C.
14. The method of claim 9, wberein the annealing occurs for 1-60 minutes.
15. The method of claim 9t -wherein annealing the single crystal diamond results in a
single crystal diamond having a hardness in excess of 140- 180 GPa.
15

A single Crystal diamond grown by
microwave plasma chemical vapor deposition an-
nealed at pressuer in excess of 4.0 GPa and healed
to temparature in excess or 1500 degrees C that has
a hardness of greater than 120GPa.A method for
monufacture a hard single crystal diamond includes
growing a single crystal diamond and annealing the
single crystal diamond at pressures in excess of 4.0
GPa and a temperature in excess of 1500 degrees C
to have a hardness in excess of 120 GPa.

Documents:

00218-kolnp-2006-abstract.pdf

00218-kolnp-2006-claims.pdf

00218-kolnp-2006-description complete.pdf

00218-kolnp-2006-drawings.pdf

00218-kolnp-2006-form 1.pdf

00218-kolnp-2006-form 3.pdf

00218-kolnp-2006-form 5.pdf

00218-kolnp-2006-international publication.pdf

00218-kolnp-2006-pct forms.pdf

00218-kolnp-2006-priority document.pdf

218-KOLNP-2006-(02-01-2012)-FORM-27.pdf

218-KOLNP-2006-CORRESPONDENCE 1.1.pdf

218-KOLNP-2006-CORRESPONDENCE.pdf

218-KOLNP-2006-FORM 1 1.1.pdf

218-KOLNP-2006-FORM 27 1.1.pdf

218-KOLNP-2006-FORM 27.pdf

218-KOLNP-2006-FORM-27.pdf

218-kolnp-2006-granted-abstract.pdf

218-kolnp-2006-granted-assignment.pdf

218-kolnp-2006-granted-claims.pdf

218-kolnp-2006-granted-correspondence.pdf

218-kolnp-2006-granted-description (complete).pdf

218-kolnp-2006-granted-drawings.pdf

218-kolnp-2006-granted-examination report.pdf

218-kolnp-2006-granted-form 1.pdf

218-kolnp-2006-granted-form 18.pdf

218-kolnp-2006-granted-form 3.pdf

218-kolnp-2006-granted-form 5.pdf

218-kolnp-2006-granted-gpa.pdf

218-kolnp-2006-granted-reply to examination report.pdf

218-kolnp-2006-granted-specification.pdf

218-KOLNP-2006-OTHERS 1.1.pdf

abstract-00218-kolnp-2006.jpg


Patent Number 235659
Indian Patent Application Number 218/KOLNP/2006
PG Journal Number 31/2009
Publication Date 31-Jul-2009
Grant Date 29-Jul-2009
Date of Filing 30-Jan-2006
Name of Patentee CARNEGIE INSTITUTION OF WASHINGTON
Applicant Address 1530 P STREET, NW, WASHINGTON, DC 20005
Inventors:
# Inventor's Name Inventor's Address
1 HEMLEY RUSSELL J 5251 BROAD BRANCH ROAD, NW, WASHINGTON, DC 20015-1305
2 MAO HO-KWANG 5251 BROAD BRANCH ROAD, NW, WASHINGTON, DC 20015-1305
3 YAN CHIH-SHIUE 5251 BROAD BRANCH ROAD, NW, WASHINGTON, DC 20015-1305
PCT International Classification Number C30B 29/04
PCT International Application Number PCT/US2004/022611
PCT International Filing date 2004-07-14
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 60/486,435 2003-07-14 U.S.A.