Classifications

• • H10P32/1204—
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
  • C30B29/02—Elements
  • C30B29/04—Diamond
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B31/00—Diffusion or doping processes for single crystals or homogeneous polycrystalline material with defined structure; Apparatus therefor
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B31/00—Diffusion or doping processes for single crystals or homogeneous polycrystalline material with defined structure; Apparatus therefor
  • C30B31/06—Diffusion or doping processes for single crystals or homogeneous polycrystalline material with defined structure; Apparatus therefor by contacting with diffusion material in the gaseous state
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D62/00—Semiconductor bodies, or regions thereof, of devices having potential barriers
  • H10D62/80—Semiconductor bodies, or regions thereof, of devices having potential barriers characterised by the materials
  • H10D62/83—Semiconductor bodies, or regions thereof, of devices having potential barriers characterised by the materials being Group IV materials, e.g. B-doped Si or undoped Ge
  • H10D62/8303—Diamond
• • H10P95/92—
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S438/00—Semiconductor device manufacturing: process
  • Y10S438/914—Doping

Definitions

• the present invention relates to a method for manufacturing n-type diamonds.
• Document JP-10- 247 624 describes an example of a method as mentioned above.
• an n-type doped diamond film is obtained by simultaneous deposition on a carbon diamond substrate, of an electron acceptor, such as boron (B) and of an electron donor, like nitrogen
• the properties of such a diamond film make it possible to use it as a semiconductor at a temperature above about 400 ° C.
• the electrical conductivity of these films decreases with temperature, and at room temperature, which is the normal temperature of use for almost all semiconductors, the components thus obtained no longer exhibit advantageous semiconductor properties.
• the object of the present invention is in particular to provide a method of manufacturing such a diamond of type n.-
• an n-type diamond comprising an n doping step, in which a donor species is diffused under vacuum.
• a diamond initially doped with an acceptor, to form donor groups containing the donor species, at a temperature less than or equal to the temperature of dissociation of complexes formed between the acceptor and the donor species.
• an n-type diamond film is obtained having a high electrical conductivity of the order of 1 ⁇ ⁇ 1 .cm ⁇ 1 at room temperature.
• This film can therefore be used in any component and electronic device operating at a temperature below the dissociation temperature of the complexes between the acceptor and the donor species, in particular ambient temperature.
• the doping step n comprises diffusing the donor species for a time long enough for the concentration of donor species in the n-type diamond obtained to be at least equal to the concentration of acceptors; the doping step n is carried out in an enclosure by forming around the diamond a plasma containing the donor species, introduced in gaseous form into the enclosure;
• the method further comprises, prior to the doping step n, a p doping step in which, under vacuum, carbon atoms and acceptor are deposited simultaneously on a diamond substrate, contained in a plasma formed around diamond substrate, to form the diamond doped with an acceptor;
• the p doping step is carried out on a diamond buffer film placed on the diamond substrate; the p doping step is carried out in an enclosure by forming around the diamond substrate a plasma comprising the acceptor and carbon, introduced in gaseous form into the enclosure; - the donor species is hydrogen; - the acceptor is boron; the acceptor is boron, and the diffusion of the hydrogen donor species is carried out at a temperature between 500 ° C and 600 ° C, and preferably of the order of 550 ° C.
• the invention relates to a diamond of type n, characterized in that it has a conductivity at 300K greater than or substantially equal to 1 ⁇ ⁇ .c ⁇ f 1 .
• the diamond thus obtained is doped with boron and hydrogen.
• FIG. 1 represents the process for the diffusion of the donor species according to the invention
• FIG. 2 represents a prior step for obtaining a film of diamond doped by an acceptor.
• FIG. 1 represents an embodiment of the method according to the invention.
• a process for obtaining n-type diamond by exposure of a diamond doped with an acceptor to a microwave hydrogen plasma could also implement other conventional methods used to generate an atomic source of the hydrogen donor species (RF plasma, continuous plasma, hot filament, or other).
• RF plasma RF plasma, continuous plasma, hot filament, or other
• another donor species could be used, for example, lithium or sodium, or the like.
• a diamond doped by an acceptor 12 is placed in a vacuum enclosure 2, on a support 6 of the enclosure, consisting for example of graphite, and possibly covered with a silicon plate, and brought to a certain temperature.
• This acceptor doped diamond 12 can be a natural or synthetic solid diamond, monocrystalline or polycrystalline, or for example a monocrystalline or polycrystalline diamond film.
• the enclosure further comprises on its side walls 8 or at its top 9 an injection nozzle 5, through which a gas containing a donor species is emitted.
• the donor species can be hydrogen in the form of one or other of its isotopes, namely normal hydrogen, deuterium or tritium, in which case the gas is for example molecular hydrogen (H 2 ).
• the gas is subjected to dissociation energy, coming from an energy source 10, in order to generate a plasma 4, containing the donor species or radicals of the donor species, around the diamond doped by an acceptor 12.
• the donor species then diffuses into the diamond doped by an acceptor 12, and forms with the acceptor atoms contained in the diamond doped by an acceptor 12 complexes between acceptor and donor species.
• Donor groups containing an atom of the donor species are formed in the diamond doped with an acceptor 12.
• the diamond heating due to the power source 10 is controlled so as to that the temperature of the diamond remains equal to or less than the temperature of dissociation of the complex between the acceptor and the donor species.
• the plasma heats the diamond doped by an acceptor 12 subjected to diffusion of the donor species.
• An external cooling / heating system 11 can optionally be used to control the temperature of the diamond so that it does not exceed the said dissociation temperature of the complex between the acceptor and the donor species.
• this dissociation temperature of the complex is around 550 ° C for the complex between boron and hydrogen.
• concentration at least equal to the concentration of boron atoms. It should be noted that hydrogen diffuses much more easily, as an H + ion, in boron-doped diamond 12, as used in the invention, than in an n-type diamond film, as produced by the methods of the prior art.
• this diffusion is carried out for 8 hours in a diamond film doped with boron 12 with a thickness of 0.5 ⁇ m and doped with 5.10 19 cm -3 atoms of boron acceptor.
• This diffusion time depends on the experimental conditions, and here makes it possible to obtain a concentration of donor species at least equal to the concentration of acceptors over the entire thickness of the diamond film. For diamonds of greater thickness or with a higher concentration of boron, obtaining a concentration of donor species at least equal to the concentration of acceptors over the entire thickness of the diamond requires a longer diffusion time.
• An n-type diamond is then obtained, as shown by the sign of the Hall effect, and having a high electrical conductivity at room temperature. If we want to dop n only a fraction of the thickness of the boron doped diamond, we adjust the hydrogen diffusion time.
• the hydrogen diffusion conditions described here are the conditions implemented in the embodiment presented, but other techniques allowing hydrogen to diffuse in a diamond doped with an acceptor, such as boron, exist and could be applied to obtain the desired distributions of the hydrogen donor species in the diamond doped with a acceptor.
• an acceptor such as boron
• the boron concentration can be high in diamonds thanks to its high solubility, it is possible to obtain in boron-doped diamond 12 a high concentration of hydrogen H donor species. In addition, this donor species easily migrates into a diamond of the type p doped with boron 12. These two characteristics make it possible to generate donor groups, comprising the donor species, at the origin of electrons made free at a temperature of 300 K with low thermal energy.
• the diffusion coefficient of hydrogen in a boron doped diamond decreases when the boron concentration in this diamond increases. If the diamond is heavily doped with boron, it is therefore only possible to obtain a concentration of the donor species at least equal to the concentration of boron over the entire thickness of the diamond, after a longer diffusion step.
• the process makes it possible to obtain a n-doped diamond of high conductivity electric at room temperature.
• the n-doped diamond obtained by the process according to the invention is also very advantageous (very conductive) for use at high temperatures, below the dissociation temperature of the complexes between acceptor and donor species, for which the films are used. n-type diamond from the prior art processes.
• n-type diamond Other steps are sometimes necessary for the implementation of an n-type diamond, depending on the use that one wishes to make of this diamond, such as for example annealing, a step of oxidizing the surface of the diamond, cleaning with acids, or others. During these operations, care should be taken not to exceed the dissociation temperature of the complexes between acceptor and donor species.
• FIG. 2 represents the production of a diamond film doped with an acceptor, such as boron by a chemical vapor deposition technique assisted by a microwave plasma (MPCVD).
• MPCVD microwave plasma
• a similar film could also be obtained by a hot filament growth technique for example.
• a substrate 1 is used, which can be a natural or synthetic diamond, for example of the monocrystalline type Ib, for example (100), or polycrystalline.
• any other type of synthetic diamond can optionally be used, and one can even have recourse to a non-diamond substrate, for example a silicon substrate, polarized or not, a SiC substrate, or an iridium substrate, for example.
• This substrate is placed in a vacuum enclosure 2, on a support 6 of the enclosure, as described above.
• This enclosure can now include on its side walls 8 or on its top 9 one or more injection nozzles 5. If one has a single injection nozzle 5, which can emit several gases simultaneously in enclosure 2, among which there is commonly found a gas containing carbon, such as CH 4 or C0 2 , and H 2 , and possibly 0 2 or N 2 . It is also possible optionally to have a single nozzle for each gas.
• the quantities of the emitted species are checked using the flow rates of each of the gases emitted.
• the gas containing carbon is methane CH 4
• the content of CH 4 relative to H 2 is 4 mol%, and can vary between 0.01% and 10%, without this value is limiting as to the scope of the invention.
• the total pressure of the gases in the enclosure is for example 10 Torr, but can vary between 1 and 100 Torr approximately.
• the gases contained in the enclosure are then subjected to an energy coming from a microwave energy source 10, which dissociates these gases and generates a plasma 4, in the enclosure, and mainly around the substrate.
• the microwave power delivered to the gas is greater than or equal to the power necessary for triggering the plasma, and may for example be of the order of 300 W in the context of a chemical vapor deposition assisted by microwave plasma. as shown here.
• the plasma heats the substrate and an external cooling / heating system 11 makes it possible to control the temperature of the substrate which is in the range from 700 ° C to 1000 ° C, and for example from 820 ° C.
• This plasma mainly contains radicals of the species present in the gases and dissociated by the energy source 10.
• the diamond film 3 is formed on the substrate by the deposition of carbon atoms resulting from the dissociation of the carbon radicals present in the plasma. 4.
• the duration of the plasma is from a few minutes to a few hours depending on the growth rate obtained and the desired thickness.
• a gas containing the acceptor For example, to obtain a diamond film doped with boron, it is common to emit diborane B 2 H 6 in gaseous form by the single injection nozzle 5, or by a nozzle specific to this gas.
• Other dopants can be emitted within the framework of the invention, typically all the elements of column III of the Mendeleev classification, such as Gallium (Ga), Aluminum (Al), Indium (In) .
• the plasma of atoms surrounding the diamond substrate then contains acceptor dopant radicals, which allows the growth of the diamond film by simultaneously incorporating carbon atoms and atoms of the acceptor dopant.
• the implementation of the above step gives a boron-doped diamond film having a concentration of approximately between 1.10 19 cm -3 to 5.10 19 cm -3 over a thickness of 0 , 5 ⁇ m.
• This diamond film doped with an acceptor can optionally be produced by deposition on a synthetic diamond buffer film (not shown), of the order of a micron or less, generally little or not doped with boron, but possibly doped with another species, which is placed between the substrate and the doped film 12 subjected to growth in order to provide this film subjected to growth an initial surface comprising fewer defects.
• the emission of the carbon-containing gas, and the gas containing the acceptor is interrupted, and the system is cooled.
• the emission of the gas containing hydrogen can then be cut, and the diamond obtained can be transported in another device, as shown in - Figure 1, in which it can be subjected to a diffusion of the donor species, using one of the techniques previously listed.
• the same enclosure can be used to distribute the donor species.
• the diamond film doped with the acceptor obtained may remain in enclosure 2 of FIG. 2 and the flow of gas containing hydrogen may not be interrupted, and only the temperature of the substrate is adapted using, for example, the external cooling / heating system 11. It is optionally possible to consider leaving the diamond film 3 doped by the acceptor in the enclosure, to cut off the flow of hydrogen containing gas, and emit the gas containing the donor species in its place, if the hydrogen is not the donor species.

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• 2002
  • 2002-12-06 FR FR0215453A patent/FR2848335B1/fr not_active Expired - Fee Related
• 2003
  • 2003-12-04 AU AU2003298415A patent/AU2003298415A1/en not_active Abandoned
  • 2003-12-04 EP EP03796163A patent/EP1568072A1/de not_active Withdrawn
  • 2003-12-04 JP JP2004558172A patent/JP4823523B2/ja not_active Expired - Fee Related
  • 2003-12-04 WO PCT/FR2003/003592 patent/WO2004053960A1/fr not_active Ceased
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