US5397428A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Nucleation enhancement for chemical vapor deposition of diamond
Assignee: University of North Carolina at Chapel Hill
•
Filing: 1992-08-28
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Granted: 1995-03-14
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Expires: 2012-08-28
Abstract
Abstract A method and apparatus for enhancing the nucleation of diamond by pretreating a substrate by electrically biasing a diamond film adjacent the substrate while exposing the substrate and the thus biased diamond film to a carbon-containing plasma. The bias pretreatment may be maintained for a time period in the range of about 1 hour to 2 hours to achieve a high diamond nucleation density. Alternatively, the biasing may be continued until diamond film formation is indicated by a change in reflectivity of the surface of the substrate. The biasing pretreating may be used to nucleate diamond heteroepitaxially on a substrate having a surface film formed of a material having a relatively close lattice match to diamond, such as beta -silicon carbide. The apparatus includes a laser reflection interferometer to monitor the surface of the substrate. The laser reflection interferometer is used to monitor growth of the diamond film and cooperates with a controller to control the processing parameters during the diamond growing process.
Inventors
- 👤 Brian R. Stoner
- 👤 Jeffrey T. Glass
- 👤 William M. Hooke
- 👤 Bradley E. Williams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 04:25
CPC Classifications
C; C23; C23C; C23C16/00; C23C16/22; C23C16/26; C23C16/27; C23C16/274; C23C16/02; C23C16/44; C23C16/458; C23C16/4581; C30; C30B; C30B25/00; C30B25/02; C30B25/10; C30B25/105; C30B29/00; C30B29/02; C30B29/04
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
78 words
A method for pretreating a substrate for the growth of a diamond film thereon, the method comprising the steps of: providing a diamond film adjacent the substrate such that the diamond film and the substrate are relatively positioned to both be exposed to a carbon-containing plasma; and electrically biasing the diamond film while exposing both the substrate and the thus biased diamond film to the carbon-containing plasma to thereby produce a high diamond nucleation density of the substrate.
Claim 2
Independent Claim
78 words
A method for pretreating a substrate for the growth of a diamond film thereon, the method comprising the steps of: providing a diamond film adjacent the substrate such that the diamond film and the substrate are relatively positioned to both be exposed to a carbon-containing plasma; and electrically biasing the diamond film while exposing both the substrate and the thus biased diamond film to the carbon-containing plasma to thereby produce a high diamond nucleation density of the substrate.
Claim 3
Dependent Claim
32 words
A method according to claim 1 further comprising the step of electrically biasing the substrate while exposing both the thus biased substrate and the thus biased diamond film to the carbon-containing plasma.
Claim 4
Dependent Claim
42 words
A method according to claim 1 wherein the substrate is positioned on a substrate holder, and wherein the step of providing the diamond film adjacent the substrate comprises the step of forming the diamond film on a portion of the substrate holder.
Claim 5
Dependent Claim
21 words
A method according to claim 3 wherein the step of electrically biasing the diamond film comprises electrically biasing the substrate holder.
Claim 6
Dependent Claim
35 words
A method according to claim 4 wherein the step of electrically biasing the substrate holder comprises biasing same at a peak absolute value of not less than about 250 volts negative with respect to ground.
Claim 7
Dependent Claim
52 words
A method according to claim 5 wherein the step of exposing both the substrate and the diamond film to the carbon-containing plasma gas comprises exposing both the substrate and the diamond film to the carbon-containing plasma gas for a period of time in the range of about 1 hour to 2 hours.
Claim 8
Dependent Claim
49 words
A method according to claim 1 wherein the step of exposing both the substrate and the diamond film to the carbon-containing plasma comprises exposing both the substrate and the diamond film to the carbon-containing plasma having an atomic percentage of carbon of not more than about 0.3 atomic percent.
Claim 9
Dependent Claim
52 words
A method according to claim 7 wherein the step of exposing both the substrate and the diamond film to the carbon-containing plasma gas comprises exposing both the substrate and the diamond film to a methane gas plasma mixture having a percentage of methane of not more than about 5 percent by weight.
Claim 10
Dependent Claim
44 words
A method according to claim 1 further comprising the steps of monitoring the reflectivity of the substrate, and discontinuing the electrical biasing responsive to a change in reflectivity of the substrate indicative of the start of growth of a diamond film on the substrate.
Claim 11
Dependent Claim
28 words
A method according to claim 1 further comprising the step of maintaining the pressure of the carbon-containing plasma in the range of about 1 torr to 100 torr.
Claim 12
Dependent Claim
31 words
A method according to claim 1 further comprising the step of maintaining the temperature of the substrate and the diamond film in the range of about 350° C to 1000° C.
Claim 13
Independent Claim
99 words
A method for pretreating a substrate for the growth of a heteroepitaxial diamond film thereon, the method comprising the steps of: forming a surface film on a substrate of a non-diamond material having a relatively close lattice match to diamond; providing a diamond film adjacent the substrate surface film such that the diamond film and the substrate surface film are relatively positioned to both be exposed to a carbon-containing plasma; and pretreating the substrate surface film by electrically biasing the diamond film while exposing both the substrate surface film and the thus biased diamond film to the carbon-containing plasma.
Claim 14
Independent Claim
99 words
A method for pretreating a substrate for the growth of a heteroepitaxial diamond film thereon, the method comprising the steps of: forming a surface film on a substrate of a non-diamond material having a relatively close lattice match to diamond; providing a diamond film adjacent the substrate surface film such that the diamond film and the substrate surface film are relatively positioned to both be exposed to a carbon-containing plasma; and pretreating the substrate surface film by electrically biasing the diamond film while exposing both the substrate surface film and the thus biased diamond film to the carbon-containing plasma.
Claim 15
Dependent Claim
34 words
A method according to claim 12 wherein the non-diamond material of the substrate is selected from the group consisting of refractory metals and their carbides, cubic-boron nitride, α-silicon carbide, β-silicon carbide, copper, and nickel.
Claim 16
Dependent Claim
36 words
A method according to claim 13 further comprising the step of electrically biasing the substrate surface film while exposing both the thus biased substrate surface film and the thus biased diamond film to the carbon-containing plasma.
Claim 17
Dependent Claim
44 words
A method according to claim 12 wherein the substrate is positioned on a substrate holder, and wherein the step of providing the diamond film adjacent the substrate surface film comprises the step of forming the diamond film on a portion of the substrate holder.
Claim 18
Dependent Claim
21 words
A method according to claim 15 wherein the step of electrically biasing the diamond film comprises electrically biasing the substrate holder.
Claim 19
Dependent Claim
35 words
A method according to claim 16 wherein the step of electrically biasing the substrate holder comprises biasing same at a peak absolute value of not less than about 250 volts negative with respect to ground.
Claim 20
Dependent Claim
49 words
A method according to claim 17 wherein the step of exposing the substrate surface film and the diamond film to the carbon-containing plasma comprises exposing the substrate surface film and the diamond film to the carbon-containing plasma for a period of time of not more than about 0.5 hours.
Claim 21
Dependent Claim
43 words
A method according to claim 12 wherein the step of pretreating the substrate surface film is performed in an evacuable chamber, and wherein the step of forming the substrate surface film comprises depositing the substrate surface film in situ in the evacuable chamber.
Claim 22
Dependent Claim
53 words
A method according to claim 12 wherein the step of exposing both the substrate surface film and the diamond film to the carbon-containing plasma comprises exposing both the substrate surface film and the diamond film to the carbon-containing plasma having an atomic percentage of carbon of not more than about 0.3 atomic percent.
Claim 23
Dependent Claim
56 words
A method according to claim 20 wherein the step of exposing both the substrate surface film and the diamond film to the carbon-containing plasma gas comprises exposing both the substrate surface film and the diamond film to a methane gas plasma mixture having a percentage of methane of not more than about 5 percent by weight.
Claim 24
Dependent Claim
50 words
A method according to claim 12 further comprising the steps of monitoring the reflectivity of the substrate surface film, and discontinuing the electrical biasing responsive to a change in reflectivity of the substrate surface film indicative of the start of growth of a diamond film on the substrate surface film.
Claim 25
Dependent Claim
28 words
A method according to claim 12 further comprising the step of maintaining the pressure of the carbon-containing plasma in the range of about 1 torr to 100 torr.
Claim 26
Dependent Claim
33 words
A method according to claim 12 further comprising the step of maintaining the temperature of the substrate surface film and the diamond film in the range of about 350° C. to 1000° C.
Claim 27
Dependent Claim
39 words
A method according to claim 12 further comprising the steps of polishing the substrate surface film, oxidizing the thus polished film to remove polishing damage, and stripping the oxide from the film to prepare same for the pretreating step.
Claim 28
Independent Claim
109 words
A method for forming a diamond film on a mirror finish substrate, said method comprising the steps of: providing a first diamond film adjacent the mirror finish substrate such that the first diamond film and the mirror finish substrate are relatively positioned to both be exposed to a carbon-containing plasma; pretreating the mirror finish substrate by electrically biasing the first diamond film while exposing both the mirror finish substrate and the thus biased first diamond film to the carbon-containing plasma; and growing a second diamond film on the thus pretreated mirror finish substrate while monitoring a relatively smooth growth surface of the second diamond film by laser reflection interferometry.
Claim 29
Independent Claim
109 words
A method for forming a diamond film on a mirror finish substrate, said method comprising the steps of: providing a first diamond film adjacent the mirror finish substrate such that the first diamond film and the mirror finish substrate are relatively positioned to both be exposed to a carbon-containing plasma; pretreating the mirror finish substrate by electrically biasing the first diamond film while exposing both the mirror finish substrate and the thus biased first diamond film to the carbon-containing plasma; and growing a second diamond film on the thus pretreated mirror finish substrate while monitoring a relatively smooth growth surface of the second diamond film by laser reflection interferometry.
Claim 30
Dependent Claim
37 words
A method according to claim 26 further comprising the step of electrically biasing the mirror finish substrate while exposing both the thus biased mirror finish substrate and the thus biased first diamond film to the carbon-containing plasma.
Claim 31
Dependent Claim
48 words
A method according to claim 26 wherein the mirror finish substrate is positioned on a substrate holder, and wherein the step of providing the first diamond film adjacent the mirror finish substrate comprises the step of forming the first diamond film on a portion of the substrate holder.
Claim 32
Dependent Claim
22 words
A method according to claim 28 wherein the step of electrically biasing the first diamond film comprises electrically biasing the substrate holder.
Claim 33
Dependent Claim
35 words
A method according to claim 29 wherein the step of electrically biasing the substrate holder comprises biasing same at a peak absolute value of not less than about 250 volts negative with respect to ground.
Claim 34
Dependent Claim
55 words
A method according to claim 26 wherein the step of exposing both the mirror finish substrate and the first diamond film to the carbon-containing plasma comprises exposing both the mirror finish substrate and the first diamond film to a carbon-containing plasma having an atomic percentage of carbon of not more than about 0.3 atomic percent.
Claim 35
Dependent Claim
57 words
A method according to claim 31 wherein the step of exposing both the mirror finish substrate and the first diamond film to the carbon-containing plasma comprises exposing both the mirror finish substrate and the first diamond film to a methane gas plasma mixture having a percentage of methane of not more than about 5 percent by weight.
Claim 36
Dependent Claim
78 words
A method according to claim 26 wherein the step of growing the second diamond film on the pretreated mirror finish substrate comprises growing the second diamond film by chemical vapor deposition, and further comprising the step of controlling the chemical vapor deposition responsive to monitoring the relatively smooth growth surface of the second diamond film by laster reflection interferometry to achieve at least one of a desired growth rate and a desired quality of the second diamond film.
Claim 37
Dependent Claim
51 words
A method according to claim 26 further comprising the steps of monitoring the surface of the substrate by laser reflection interferometry during the pretreating step, and discontinuing the electrical biasing responsive to a change in the reflectivity of the substrate indicative of the start of growth of the second diamond film.
Claim 38
Dependent Claim
28 words
A method according to claim 26 further comprising the step of maintaining the pressure of the carbon-containing plasma in the range of about 1 torr to 100 torr.
Claim 39
Dependent Claim
34 words
A method according to claim 26 further comprising the step of maintaining the temperature of the mirror finish substrate and the first diamond film in the range of about 350° C. to 1000° C.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-03-13 | 1998-09-12 | 1999-03-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-03-13 | 2002-09-12 | 2003-03-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-03-13 | 2006-09-12 | 2007-03-14 | $7700.00 | Window Closed / Lapsed |