CA2015513A1 - Apparatus for synthetic diamond deposition including spring-tensioned filaments and substrate cooling means - Google Patents
Apparatus for synthetic diamond deposition including spring-tensioned filaments and substrate cooling meansInfo
- Publication number
- CA2015513A1 CA2015513A1 CA 2015513 CA2015513A CA2015513A1 CA 2015513 A1 CA2015513 A1 CA 2015513A1 CA 2015513 CA2015513 CA 2015513 CA 2015513 A CA2015513 A CA 2015513A CA 2015513 A1 CA2015513 A1 CA 2015513A1
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- filaments
- substrates
- diamond
- deposition
- chamber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
APPARATUS FOR SYNTHETIC DIAMOND
DEPOSITION INCLUDING SPRING-TENSIONED
FILAMENTS AND SUBSTRATE COOLING MEANS
Abstract Diamond is deposited by chemical vapor deposition on two parallel substrates, by means of a plurality of filaments between said substrates. The substrates and filaments are in vertical configuration and the filaments are linear and spring-tensioned to compensate for thermal expansion and expansion caused by filament carburization.
The apparatus includes at least one and preferably two heat sinks to maintain substrate temperature in the range of 900-1000°C, for optimum rate of diamond deposition.
DEPOSITION INCLUDING SPRING-TENSIONED
FILAMENTS AND SUBSTRATE COOLING MEANS
Abstract Diamond is deposited by chemical vapor deposition on two parallel substrates, by means of a plurality of filaments between said substrates. The substrates and filaments are in vertical configuration and the filaments are linear and spring-tensioned to compensate for thermal expansion and expansion caused by filament carburization.
The apparatus includes at least one and preferably two heat sinks to maintain substrate temperature in the range of 900-1000°C, for optimum rate of diamond deposition.
Description
2 ~ . 3 ~ L~S _~C~IC~G s~R~ ED
_~:2lC~L~ uL~ LL~TE COO~ING ME~S
This invention relates to the chemical vapor depo-sition of diamond, and more particularly to an apparatus foruse in such deposition.
Various methods are known for the synthetic pro-duction of diamond. In particular, the deposition of diamond coatings on substrates to produce cutting and abrasive tools is known.
One cl ss of methods developed in recent yeaxs for synthetic diamond deposition consists of the chemicai vapor deposition (hereinafter sometimes "CVD") methods. For a general summaxy of various diamond deposition methods including CVD methods, reference is made to Sh5~LJUaL_~
En~ineerinq~e~a, ~ QL, 24-39 (May 15, 1989) In the CVD methods, a mixture of hydrogen and a hydrocarbon gas such as methane is thermally activated and passed into contact with a substrate. The hydrogen gas is converted to atomic hydrogen which reacts with the hydro-carbon to form elemental carbon, which deposits on ~he`
substrate in the form of diamond. Many of the CVD diamond coating methods, hereinafter referred to as "filament"
methods, employ one or more re~cistance heating units includ-ing heated wires or filaments, typically at temperatures of at least 2000 C, to provide the high activation temperatures at which th se conversions take place.
Various problems have been encountered in filament methods of CVD diamond deposition, and they have inhibited to a considerable extent the usefulness thereof on a commercial scal~. For example, it is difficult to create conditions under which the deposition rate of diamond is high enough to . , .
, . , -, , 2 ~ 3 be commercially feasible. Numerous methods employing a horizontal configuration of the substrate(s) and filaments, with helically wound filaments, have been disclosed, but for ~he most part the deposition rate afforded thereby is low.
Also, the high substrate temperature usually produced is incompatible with a high rate of diamond deposi-tion. At the filament temperatures which produce atomic hydrogen in the necessary proportions, the substrate reaches a temperature higher than about 1000-C. Optimum substrate temperatures for diamond deposition are in the range of 900-1000 C, and thus the substrate temperatures generated are too high for rapid deposition.
Finally, numerous problems with the filaments have been observed. Substantial expansion thereof occurs at the aforementioned high temperatures; this is, in part, thermal expansion but to a greater extent, in the case of the tungsten filaments frequently employed, is the result of carburization, forming tungsten carbide with concomitant expansion to the extent of about 20%. If such expansion is uncontrolled, filament breakage and/or contact between the filaments and substrate can occur, either of which will terminate diamond deposition.
The damage resulting from carburization is particularly severe when a helical filament configuration is employed. Carburization is accompanied by cracking of the tungsten carbide, often in a spiral configuration which can cause deformation of a helically wound filament in unpredict-able directions. The deposition operation is thus usually prematurely ~borted, much short of the 30-40 day period normally required for the deposition of a diamond film of 0.5-1.0 mm. in thickness.
The present invention is based on several discoveries of conditions which promote optimum diamond deposition on substrates. In the first place, it has been 2 0 ~ 3 found that nucleation and growth o~ diamond is maximized when the reactor configuration includes two substantially parallel substrates on opposite sides of a plurality of filaments, rather than substrates horizontally configured, or vertically S in a square or cylindrical array or one substrate between banks of filaments. In the second place, long filament life is attained with linear filaments which are spring-tensioned to compensate for thermal expansion and expansion caused by carburization. In the third place, employment of at least one heat sink to regulate substrate temperature permits control of the deposition reaction to optimize diamond growth rates.
The invention provides an apparatus for impro~ed production of CVD diamond coatings by the filament method.
The features of the invention permit closer control of fila-ment configuration than has previously been possible, as well as control of substrate temperature for maximization of deposition rate. One result is an illcrease in filament life, which enables the deposition pro~ess to be continued until a coating of substantial thickness is produced.
Accordingly, the invention is directed to apparatus for deposition of diamond on substrat:es by chemical vapor deposition, comprising:
a closed reaction chamber having at least one gas ~5 inlet and at least one exhaust means~ said chamber being capable of being maintained at a pressure below atmospheric;
support means for supporting said substrates in said chamber parallel to each other and spaced apart to permit gas flow between said substrates;
resistance heating means comprising a plurality of vertically extending linear, electrically conduc~ive filaments situated substantially equidistant from said substrates, each of said filaments being secured at one end to a fixed electrode and at the other to a moveable electrode 2 ~ 3 for supplying power to said filaments and thereby heating them;
a plurality of spring means attached to said moveable electrodes, for holding said filaments taut and substantially parallel to said substrates without causing breakage of said filaments; and substrate cooling means situated adjacent one of said substrates on the opposite side from said filaments.
The invention will be described in detail with reference to the drawings, in which:
FIGURE l is a schematic side view of an illustrative apparatus according to the present invention;
FIGURE 2 is a cutaway view of said apparatus on the line 2-2 of FIGURE l;
FIGURE ~ is a further cutaway view on the line 3-3 of FIGURE 2; and FIGURE 4 is a detail view of certain aspects of the filament tensioning mechanism which forms part of the inven-tion.
Referring now to the drawings, there are depicted the interior features of a CVD diamond deposition unit according to the present invention. All of said features are enclosed in a reaction chamber (not shown) which is air-tight and thus capable of being main-tained at reduced pressure and is fitted with a suitable gas inIet and an exhaus~ port. All portions of the apparatus which are present in the reaction chamber are constructed of suitable heat-resistant materials, as necessary to wi~hstand filament temperatures on the order of abou~ 2000 C and substrate temperatures up to about ~0 lOOO C. Quartz is an illustrative non-conductive heat-resistant material suitable for this purpose.
The features of the apparatus and associated articles which are shown in the drawings include a pair of substrates 1, which are normally planar although they may be ~;
2 ~ 3 gently curved. Any substrate material suitable for diamond deposition thereon may be employed; examples of such materials are boron, boron nitride, platinum, graphite, molybdenum, copper, aluminum nitride, silver, iron, nickel, silicon, alumina and silica, as well as combinations thereof.
Metallic molybdenum substrates are particularly suitable under many conditions and are often preferred. Supports 2 serve as support means for holding substrates 1 in position parallel to each other and at a suitable spacing for deposition to take place.
The apparatus also contains resistance heating means comprising two electrodes and a number of vertically extending linear, electrically conductive filaments or wires (hereinafter generically designated "filaments"3, and otherwise being of conventional design and circuitry. The material of which said filaments are comprised is not critical, any material known in the art as suitable for this purpose being acceptable. Illustrative materials are metallic tungsten, tantalum, molybdenum and rhenium; because of its relatively low cost and particular suitability, tungsten is often preferred. Filament diameters of about 0.2-l.0 mm. are typical, with about 0.8 mm~ frequently being preferred.
The filaments are located between said substrates, parallel to and substantially equi~istant therefrom.
Distances from filaments to substrates are generally on the order of 5-lO mm.
In the drawings, fixed electrode 4 is grounded and is fixedly attached to a number of said filaments, one of which is designated 5. Since a plurality of filaments and associated structure are present, reference thereto hereinafter and in the drawings will be to only one; it should be understood that the total number thereof is not critical to the invention.
S ~ 3 Insulator 6 separates the fixed electrode and its base from conducting element 7. The latter is conductively connected via conductor 8, typically of copper braid, to moveable electrode 9.
Said moveable electrode is shown as connected to filament 5 via a bearing. The bearing construction depicted in the drawings, and especially in FIGURE 4, includes rod 30 fixedly attached to moveable electrode 9 and passing through holes ll in the bottom portion of support frame 15 and in conducting element 7; and plug 12 fixedly fastened to rod 30 by set screw 13, said plug 12 having sufficient clearance from conducting element 7 to permit filament 5 to be maintained taut as described hereinafter, but insufficient to permit overtensioning thereof, which could cause breakage of the filament.
Filament 5 is held taut and substantially parallel to substrates l by spring lO, fixedly fastened to support frame 15 by rod 16 and fastening nuts 17. Although the spring is depicted as being an extension coil spring providing tension in the stretching rnode, it will be apparent to one skilled in the art that similar results could be obtained employing other types of springs. For example, compression coil springs operating in he compressiYe mode o~
cantilevered flat or coil springs operating in the bending 2S mode could be used.
It is within the scope of the invention for springs lO to comprise an insulating material or one with conductive properties so diff~rent from those of the resistance heating means that no appreciable conduction of current through said springs occurs. Most often, however, it will be desired to make said springs from readily available metal such as steel.
It may then be necessary to electrically isolate spring lO
and frame 15 from the resistance heating means, in order to avoid overheating thereof.
.
2 ~ 3 Accordingly, the attachment shown between spring 10 and moveable electrode 9 is achieved via insulating ring 14, comprising a suitable non-conductive material such as quartz or high temperature-resistant plastic. Likewise, insulator 31, typically of temperature-resistant plastic such as poly-tetrafluoroethylene, is located between conductor 7 and frame 15 .
It is highly desirable to maintain substrates 1 at temperatures in the range of about 900-lOOO C, since within this range minimum reaction occurs between the hydrogen pre-sent in the gas mixture and the elemental carbon formed from the hydrocarbon therein; thus, said elemental carbon remains available to deposit as diamond at a high growth rate on the substrate. Absent any provisions for independently controlling substrate temperature, said temperature frequently exc~eds lOOQ C and the diamond growth rate decreases substantially.
According to the invention, the desired temperature control is achieved by substrate cooling means comprising at least one and preferably two heat sinks 18. Each heat sink is typically made of metallic copper and cooled by attached serpentine tubing 21 (also usually of copper) fitted with cooling water inlet and outlet 19 and 20, respectively. The distance of heat sink 18 from substrate 1 is adjusted by a conventional screw mechanism controlled by crank 22, and said distance and the flow rate of wa~er through the tubing are ad~usted, either manually or automatically via suitable sensors, to maintain the substrate within the desired temperature range.
In operation, the reaction chamber of the apparatus of this invention is maintained at a pressure up to About 760 torr, typically on the order of 10 torr. A mixture of hydro gen and a hydrocarbon, most often methane and generally present in an amount up to about 2% by weight based on total : . ' . ' , 2 ~
gases, is passed into the chamber and a current is passed through the electrodes and filaments to heat the filaments to a temperature of at leas~ about 2000 C. With the substrate configuration employed, gas diffusion between the substrates and in contact with the filaments promotes excellent nucleation and growth of diamond particles.
The heat sink(s) is maintained at a distance from the substrate and water passage through the tubing associated therewith is maintained at a rate to pro~ide a substrate temperature in the range of about 900-lOOO C, most often about 950 C. At such temperatures, diamond growth rate approaches its highest value. Spring tension is maintained on the filaments as previously described, whereby they remain in substantially planar configura~ion even with the occurrence of thermal expansion and expansion due to carburization. Using this combination of elements, it is possible to grow diamond films with thicknesses up to about 1 mm., or even greater on occasion, within a time span of 30-40 days without filament breakage or other untoward events occurring.
.~ -,' ':' . ................ '.~ . .
; .
_~:2lC~L~ uL~ LL~TE COO~ING ME~S
This invention relates to the chemical vapor depo-sition of diamond, and more particularly to an apparatus foruse in such deposition.
Various methods are known for the synthetic pro-duction of diamond. In particular, the deposition of diamond coatings on substrates to produce cutting and abrasive tools is known.
One cl ss of methods developed in recent yeaxs for synthetic diamond deposition consists of the chemicai vapor deposition (hereinafter sometimes "CVD") methods. For a general summaxy of various diamond deposition methods including CVD methods, reference is made to Sh5~LJUaL_~
En~ineerinq~e~a, ~ QL, 24-39 (May 15, 1989) In the CVD methods, a mixture of hydrogen and a hydrocarbon gas such as methane is thermally activated and passed into contact with a substrate. The hydrogen gas is converted to atomic hydrogen which reacts with the hydro-carbon to form elemental carbon, which deposits on ~he`
substrate in the form of diamond. Many of the CVD diamond coating methods, hereinafter referred to as "filament"
methods, employ one or more re~cistance heating units includ-ing heated wires or filaments, typically at temperatures of at least 2000 C, to provide the high activation temperatures at which th se conversions take place.
Various problems have been encountered in filament methods of CVD diamond deposition, and they have inhibited to a considerable extent the usefulness thereof on a commercial scal~. For example, it is difficult to create conditions under which the deposition rate of diamond is high enough to . , .
, . , -, , 2 ~ 3 be commercially feasible. Numerous methods employing a horizontal configuration of the substrate(s) and filaments, with helically wound filaments, have been disclosed, but for ~he most part the deposition rate afforded thereby is low.
Also, the high substrate temperature usually produced is incompatible with a high rate of diamond deposi-tion. At the filament temperatures which produce atomic hydrogen in the necessary proportions, the substrate reaches a temperature higher than about 1000-C. Optimum substrate temperatures for diamond deposition are in the range of 900-1000 C, and thus the substrate temperatures generated are too high for rapid deposition.
Finally, numerous problems with the filaments have been observed. Substantial expansion thereof occurs at the aforementioned high temperatures; this is, in part, thermal expansion but to a greater extent, in the case of the tungsten filaments frequently employed, is the result of carburization, forming tungsten carbide with concomitant expansion to the extent of about 20%. If such expansion is uncontrolled, filament breakage and/or contact between the filaments and substrate can occur, either of which will terminate diamond deposition.
The damage resulting from carburization is particularly severe when a helical filament configuration is employed. Carburization is accompanied by cracking of the tungsten carbide, often in a spiral configuration which can cause deformation of a helically wound filament in unpredict-able directions. The deposition operation is thus usually prematurely ~borted, much short of the 30-40 day period normally required for the deposition of a diamond film of 0.5-1.0 mm. in thickness.
The present invention is based on several discoveries of conditions which promote optimum diamond deposition on substrates. In the first place, it has been 2 0 ~ 3 found that nucleation and growth o~ diamond is maximized when the reactor configuration includes two substantially parallel substrates on opposite sides of a plurality of filaments, rather than substrates horizontally configured, or vertically S in a square or cylindrical array or one substrate between banks of filaments. In the second place, long filament life is attained with linear filaments which are spring-tensioned to compensate for thermal expansion and expansion caused by carburization. In the third place, employment of at least one heat sink to regulate substrate temperature permits control of the deposition reaction to optimize diamond growth rates.
The invention provides an apparatus for impro~ed production of CVD diamond coatings by the filament method.
The features of the invention permit closer control of fila-ment configuration than has previously been possible, as well as control of substrate temperature for maximization of deposition rate. One result is an illcrease in filament life, which enables the deposition pro~ess to be continued until a coating of substantial thickness is produced.
Accordingly, the invention is directed to apparatus for deposition of diamond on substrat:es by chemical vapor deposition, comprising:
a closed reaction chamber having at least one gas ~5 inlet and at least one exhaust means~ said chamber being capable of being maintained at a pressure below atmospheric;
support means for supporting said substrates in said chamber parallel to each other and spaced apart to permit gas flow between said substrates;
resistance heating means comprising a plurality of vertically extending linear, electrically conduc~ive filaments situated substantially equidistant from said substrates, each of said filaments being secured at one end to a fixed electrode and at the other to a moveable electrode 2 ~ 3 for supplying power to said filaments and thereby heating them;
a plurality of spring means attached to said moveable electrodes, for holding said filaments taut and substantially parallel to said substrates without causing breakage of said filaments; and substrate cooling means situated adjacent one of said substrates on the opposite side from said filaments.
The invention will be described in detail with reference to the drawings, in which:
FIGURE l is a schematic side view of an illustrative apparatus according to the present invention;
FIGURE 2 is a cutaway view of said apparatus on the line 2-2 of FIGURE l;
FIGURE ~ is a further cutaway view on the line 3-3 of FIGURE 2; and FIGURE 4 is a detail view of certain aspects of the filament tensioning mechanism which forms part of the inven-tion.
Referring now to the drawings, there are depicted the interior features of a CVD diamond deposition unit according to the present invention. All of said features are enclosed in a reaction chamber (not shown) which is air-tight and thus capable of being main-tained at reduced pressure and is fitted with a suitable gas inIet and an exhaus~ port. All portions of the apparatus which are present in the reaction chamber are constructed of suitable heat-resistant materials, as necessary to wi~hstand filament temperatures on the order of abou~ 2000 C and substrate temperatures up to about ~0 lOOO C. Quartz is an illustrative non-conductive heat-resistant material suitable for this purpose.
The features of the apparatus and associated articles which are shown in the drawings include a pair of substrates 1, which are normally planar although they may be ~;
2 ~ 3 gently curved. Any substrate material suitable for diamond deposition thereon may be employed; examples of such materials are boron, boron nitride, platinum, graphite, molybdenum, copper, aluminum nitride, silver, iron, nickel, silicon, alumina and silica, as well as combinations thereof.
Metallic molybdenum substrates are particularly suitable under many conditions and are often preferred. Supports 2 serve as support means for holding substrates 1 in position parallel to each other and at a suitable spacing for deposition to take place.
The apparatus also contains resistance heating means comprising two electrodes and a number of vertically extending linear, electrically conductive filaments or wires (hereinafter generically designated "filaments"3, and otherwise being of conventional design and circuitry. The material of which said filaments are comprised is not critical, any material known in the art as suitable for this purpose being acceptable. Illustrative materials are metallic tungsten, tantalum, molybdenum and rhenium; because of its relatively low cost and particular suitability, tungsten is often preferred. Filament diameters of about 0.2-l.0 mm. are typical, with about 0.8 mm~ frequently being preferred.
The filaments are located between said substrates, parallel to and substantially equi~istant therefrom.
Distances from filaments to substrates are generally on the order of 5-lO mm.
In the drawings, fixed electrode 4 is grounded and is fixedly attached to a number of said filaments, one of which is designated 5. Since a plurality of filaments and associated structure are present, reference thereto hereinafter and in the drawings will be to only one; it should be understood that the total number thereof is not critical to the invention.
S ~ 3 Insulator 6 separates the fixed electrode and its base from conducting element 7. The latter is conductively connected via conductor 8, typically of copper braid, to moveable electrode 9.
Said moveable electrode is shown as connected to filament 5 via a bearing. The bearing construction depicted in the drawings, and especially in FIGURE 4, includes rod 30 fixedly attached to moveable electrode 9 and passing through holes ll in the bottom portion of support frame 15 and in conducting element 7; and plug 12 fixedly fastened to rod 30 by set screw 13, said plug 12 having sufficient clearance from conducting element 7 to permit filament 5 to be maintained taut as described hereinafter, but insufficient to permit overtensioning thereof, which could cause breakage of the filament.
Filament 5 is held taut and substantially parallel to substrates l by spring lO, fixedly fastened to support frame 15 by rod 16 and fastening nuts 17. Although the spring is depicted as being an extension coil spring providing tension in the stretching rnode, it will be apparent to one skilled in the art that similar results could be obtained employing other types of springs. For example, compression coil springs operating in he compressiYe mode o~
cantilevered flat or coil springs operating in the bending 2S mode could be used.
It is within the scope of the invention for springs lO to comprise an insulating material or one with conductive properties so diff~rent from those of the resistance heating means that no appreciable conduction of current through said springs occurs. Most often, however, it will be desired to make said springs from readily available metal such as steel.
It may then be necessary to electrically isolate spring lO
and frame 15 from the resistance heating means, in order to avoid overheating thereof.
.
2 ~ 3 Accordingly, the attachment shown between spring 10 and moveable electrode 9 is achieved via insulating ring 14, comprising a suitable non-conductive material such as quartz or high temperature-resistant plastic. Likewise, insulator 31, typically of temperature-resistant plastic such as poly-tetrafluoroethylene, is located between conductor 7 and frame 15 .
It is highly desirable to maintain substrates 1 at temperatures in the range of about 900-lOOO C, since within this range minimum reaction occurs between the hydrogen pre-sent in the gas mixture and the elemental carbon formed from the hydrocarbon therein; thus, said elemental carbon remains available to deposit as diamond at a high growth rate on the substrate. Absent any provisions for independently controlling substrate temperature, said temperature frequently exc~eds lOOQ C and the diamond growth rate decreases substantially.
According to the invention, the desired temperature control is achieved by substrate cooling means comprising at least one and preferably two heat sinks 18. Each heat sink is typically made of metallic copper and cooled by attached serpentine tubing 21 (also usually of copper) fitted with cooling water inlet and outlet 19 and 20, respectively. The distance of heat sink 18 from substrate 1 is adjusted by a conventional screw mechanism controlled by crank 22, and said distance and the flow rate of wa~er through the tubing are ad~usted, either manually or automatically via suitable sensors, to maintain the substrate within the desired temperature range.
In operation, the reaction chamber of the apparatus of this invention is maintained at a pressure up to About 760 torr, typically on the order of 10 torr. A mixture of hydro gen and a hydrocarbon, most often methane and generally present in an amount up to about 2% by weight based on total : . ' . ' , 2 ~
gases, is passed into the chamber and a current is passed through the electrodes and filaments to heat the filaments to a temperature of at leas~ about 2000 C. With the substrate configuration employed, gas diffusion between the substrates and in contact with the filaments promotes excellent nucleation and growth of diamond particles.
The heat sink(s) is maintained at a distance from the substrate and water passage through the tubing associated therewith is maintained at a rate to pro~ide a substrate temperature in the range of about 900-lOOO C, most often about 950 C. At such temperatures, diamond growth rate approaches its highest value. Spring tension is maintained on the filaments as previously described, whereby they remain in substantially planar configura~ion even with the occurrence of thermal expansion and expansion due to carburization. Using this combination of elements, it is possible to grow diamond films with thicknesses up to about 1 mm., or even greater on occasion, within a time span of 30-40 days without filament breakage or other untoward events occurring.
.~ -,' ':' . ................ '.~ . .
; .
Claims (12)
1. Apparatus for deposition of diamond on substrates by chemical vapor deposition, comprising:
a closed reaction chamber having at least one gas inlet and at least one exhaust means, said chamber being capable of being maintained at a pressure below atmospheric;
support means for supporting said substrates in said chamber parallel to each other and spaced apart to permit gas flow between said substrates;
resistance heating means comprising a plurality of vertically extending linear, electrically conductive filaments situated substantially equidistant from said substrates, each of said filaments being secured at one end to a fixed electrode and at the other to a moveable electrode for supplying power to said filaments and thereby heating them;
a plurality of spring means attached to said moveable electrodes, for holding said filaments taut and substantially parallel to said substrates without causing breakage of said filaments; and substrate cooling means situated adjacent one of said substrates on the opposite side from said filaments.
a closed reaction chamber having at least one gas inlet and at least one exhaust means, said chamber being capable of being maintained at a pressure below atmospheric;
support means for supporting said substrates in said chamber parallel to each other and spaced apart to permit gas flow between said substrates;
resistance heating means comprising a plurality of vertically extending linear, electrically conductive filaments situated substantially equidistant from said substrates, each of said filaments being secured at one end to a fixed electrode and at the other to a moveable electrode for supplying power to said filaments and thereby heating them;
a plurality of spring means attached to said moveable electrodes, for holding said filaments taut and substantially parallel to said substrates without causing breakage of said filaments; and substrate cooling means situated adjacent one of said substrates on the opposite side from said filaments.
2. Apparatus according to claim 1 including a pair of substrate cooling means on the opposite side from said filaments of each of said substrates.
3. Apparatus according to claim 2 further comprising means for electrically isolating said spring means from said filaments.
4. Apparatus according to claim 3 wherein said fixed electrode is located below the space between said substrates.
5. Apparatus according to claim 4 wherein the filaments comprise metallic tungsten.
6. Apparatus according to claim 4 wherein the substrate cooling means comprise metallic copper with provision for passage of cooling water.
7. Apparatus according to claim 4 further comprising means for adjusting the distance from the substrates to the substrate cooling means.
8. Apparatus according to claim 4 wherein the spring means comprise extension coil springs.
9. Apparatus according to claim 4 wherein the spring means comprise compression coil springs.
10. Apparatus according to claim 4 wherein the spring means comprise cantilevered springs.
11. Apparatus for deposition of diamond on a pair of planar vertical substrates by chemical vapor deposition, comprising:
a closed reaction chamber having at least one gas inlet and at least one exhaust means, said chamber being capable of being maintained at a pressure below atmospheric;
support means for supporting said substrates in said chamber, parallel to each other and spaced apart to permit gas flow between said substrates;
resistance heating means comprising a plurality of vertically extending linear tungsten filaments situated substantially equidistant from said substrates, each of said filaments being secured at the lower end to a fixed electrode and at the upper end to a moveable electrode for supplying power to said filaments and thereby heating them;
a plurality of extension coil springs attached to said moveable electrodes, for holding said filaments taut and substantially parallel to said substrates without causing breakage of said filaments;
means for electrically isolating said springs from said filaments; and a pair of moveable heat sinks situated adjacent said substrates on the opposite side from said filaments, said heat sinks comprising metallic copper with provision for passage of cooling water.
a closed reaction chamber having at least one gas inlet and at least one exhaust means, said chamber being capable of being maintained at a pressure below atmospheric;
support means for supporting said substrates in said chamber, parallel to each other and spaced apart to permit gas flow between said substrates;
resistance heating means comprising a plurality of vertically extending linear tungsten filaments situated substantially equidistant from said substrates, each of said filaments being secured at the lower end to a fixed electrode and at the upper end to a moveable electrode for supplying power to said filaments and thereby heating them;
a plurality of extension coil springs attached to said moveable electrodes, for holding said filaments taut and substantially parallel to said substrates without causing breakage of said filaments;
means for electrically isolating said springs from said filaments; and a pair of moveable heat sinks situated adjacent said substrates on the opposite side from said filaments, said heat sinks comprising metallic copper with provision for passage of cooling water.
12. The invention as defined in any of the preceding claims including any further features of novelty disclosed.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US38921089A | 1989-08-03 | 1989-08-03 | |
| US389,210 | 1989-08-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2015513A1 true CA2015513A1 (en) | 1991-02-03 |
Family
ID=23537313
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2015513 Abandoned CA2015513A1 (en) | 1989-08-03 | 1990-04-26 | Apparatus for synthetic diamond deposition including spring-tensioned filaments and substrate cooling means |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2015513A1 (en) |
| ZA (1) | ZA905695B (en) |
-
1990
- 1990-04-26 CA CA 2015513 patent/CA2015513A1/en not_active Abandoned
- 1990-07-19 ZA ZA905695A patent/ZA905695B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| ZA905695B (en) | 1991-07-31 |
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