WO2022135627A1 - A semiconductor having increased dopant concentration, a method of manufacturing thereof and a chemical reactor - Google Patents

A semiconductor having increased dopant concentration, a method of manufacturing thereof and a chemical reactor Download PDF

Info

Publication number
WO2022135627A1
WO2022135627A1 PCT/CZ2021/050154 CZ2021050154W WO2022135627A1 WO 2022135627 A1 WO2022135627 A1 WO 2022135627A1 CZ 2021050154 W CZ2021050154 W CZ 2021050154W WO 2022135627 A1 WO2022135627 A1 WO 2022135627A1
Authority
WO
WIPO (PCT)
Prior art keywords
gas
semiconductor
reactor
injecting
dopant element
Prior art date
Application number
PCT/CZ2021/050154
Other languages
French (fr)
Inventor
Vincent Mortet
Andrew Taylor
Marina DAVYDOVA
Nicolas Lambert
Miroslav LAMAC
Original Assignee
Fyzikalni Ustav Av Cr, V.V.I.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Fyzikalni Ustav Av Cr, V.V.I. filed Critical Fyzikalni Ustav Av Cr, V.V.I.
Publication of WO2022135627A1 publication Critical patent/WO2022135627A1/en

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02612—Formation types
    • H01L21/02617—Deposition types
    • H01L21/0262—Reduction or decomposition of gaseous compounds, e.g. CVD
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/26—Deposition of carbon only
    • C23C16/27—Diamond only
    • C23C16/271—Diamond only using hot filaments
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/26—Deposition of carbon only
    • C23C16/27—Diamond only
    • C23C16/278—Diamond only doping or introduction of a secondary phase in the diamond
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/455—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
    • C23C16/45523—Pulsed gas flow or change of composition over time
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
    • C23C16/511—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using microwave discharges
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02518—Deposited layers
    • H01L21/02521—Materials
    • H01L21/02524—Group 14 semiconducting materials
    • H01L21/02527—Carbon, e.g. diamond-like carbon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02518—Deposited layers
    • H01L21/0257—Doping during depositing
    • H01L21/02573—Conductivity type

Definitions

  • the present invention pertains to material science, more particularly to semiconductor materials suitable for electronics and/or electrochemistry.
  • the present invention relates to deposition of epitaxial layers or polycrystalline semiconductor layers with appropriate seeding pre-treatment, e.g. deposition of diamond seed, on a substrate.
  • the present invention relates to a method of doped semiconductor production, in particular via activated chemical vapour deposition, such as microwave plasma enhanced CVD or hot filament CVD methods.
  • the present invention relates to a chemical reactor suitable for production such semiconductor suitable for electronics and/or electrochemical electrodes.
  • Diamond possesses physical and electrical properties such as high breakdown voltage, high thermal conductivity, small dielectric constant, wide band gap and excellent radiation hardness which qualifies its suitability for industrial application in high power electronics. Besides that, diamond is also chemically stable and is considered as a one of the biocompatible material. It is known, e.g. from WO2019042484, that diamond can be used as a part of chemically stable electrochemical electrodes, heat spreaders with extreme thermal conductivity, radiation hard particle physics detectors, and high frequency surface acoustic wave filters.
  • Diamond Electrical properties of diamond are controlled by the addition of boron (p-type) and phosphorous (n-type) impurities.
  • Diamond is also a unique material for quantum application with easily interrogable and controllable qubits at room temperature using the nitrogen vacancy or silicon vacancy defects.
  • the key technology in the use of diamond for the fabrication of the next generation of quantum technologies and electronics is doping, i.e. the careful addition of impurities in diamond.
  • Significant progresses have been achieved in the synthesis of doped diamond, yet the level of dopant incorporation remains limited depending on the substrate orientation, deposition conditions and the type of dopant (B, P, N, Si, Ge, etc.).
  • the diamond growth process uses activated vapor or gas of organic compounds (generally methane) as carbon precursor for the diamond growth.
  • the carbon precursor is generally (but not limited) diluted in hydrogen at different concentrations.
  • the vapor (or gas) of the dopant elements’ precursors are added in the gas mixture for the incorporation of the element during the growth process.
  • CVD reactors for diamond deposition. They have in common a reaction cavity with different controlled precursor gas inputs, a pressure control system and a gas activation system.
  • the gas mixture needs to be activated to produce the chemicals at the origin of the diamond growth and the incorporation of dopants.
  • the gases activation is carried out either electrically by creating an electrical discharge (i.e. a plasma) using generally microwave energy or thermal energy using hot filaments.
  • the temperature of the substrate is generally above 600 °C, although diamond deposition at temperature as low as room temperature has been reported.
  • the substrates are either diamond crystals for epitaxial growth or pre-treated materials that can withstand the process parameters (high temperature, reactive atomic hydrogen species, etc.), i.e.
  • the diamond growth by CVD methods is directly related to the concentration of reactive species present in the gas phase. Although the exact process of diamond growth is not exactly known, it is acknowledged that atomic hydrogen (possibly halogen, e.g. chlorine) and CH X radical (with x ⁇ 3) present in the activated process gas are essential for the diamond growth. Although the mechanism of dopant incorporation is not fully understood, the dopant (B, P, N, Si, etc.) incorporation also results from the activated species present in the gas phase.
  • atomic hydrogen possibly halogen, e.g. chlorine
  • CH X radical with x ⁇ 3
  • the example, shown in Fig. 1 represents unwanted cross-reactions in the gas phase that can result of the addition of the dopant precursor in process gas used for the growth of undoped diamond.
  • these unwanted reactions severely limit the incorporation of phosphorus in diamond and decrease the deposition rate at high concentration of the phosphorus precursor as illustrated below.
  • the cross-reactions between the carbon precursor and the dopant precursor is not limited to phosphorus doping.
  • US20170330746 discloses an apparatus and a method for manufacturing diamond electronic devices.
  • the method comprises the step of positioning a substrate of diamond electronic device to a plasma enhanced chemical vapour deposition (PECVD) reactor, wherein the condition in the reactor is modulated, in particular controlling temperature of the substrate by manipulating microwave power, chamber pressure, and gas flow rates.
  • the modulation of temperature is above 600 °C and is pulsed.
  • the pulsed variation of temperature is provided within 6 cycles in the range from 600 °C up to 1000 °C.
  • increase of dopant concentration in a diamond electronic device can be observed due to pulsed modulation of temperature.
  • the flow rate of methane precursor, resp. phosphorus precursor is stable, i.e. there is a continues flow of both precursors.
  • W00000677 relates to a method for doping semiconductor materials.
  • One of the semiconductor materials is diamond.
  • an increased dopant concentration with nitrogen or boron can be observed according to a method disclosed therein.
  • the method comprises steps of controlling of a dopant concentration introduced into an epitaxial film during CVD by controlling energy of dopant atoms impinged on the film.
  • the energy of dopant can be modulated via flow condition which can be continues or pulsed.
  • pulse regime was used, both precursors in a gas sources were introduced in pulsed regime simultaneously.
  • US8017182 discloses a method for an epitaxy layer formation.
  • the layers comprise metal and semi-metal oxides and nitrides deposited on a wafer substrate.
  • the layers are deposited on the substrate using atomic layer deposition (ALD) method and chemical vapour deposition (CVD) method.
  • ALD atomic layer deposition
  • CVD chemical vapour deposition
  • Document further discloses combination of ALD and CVD in pulse regime.
  • the present invention relates to a method of production an extrinsic semiconductor by chemical vapour deposition.
  • doping is the intentional introduction of impurities into an intrinsic semiconductor for modulating its electrical, optical and structural properties.
  • the doped material is referred to as an extrinsic semiconductor.
  • the method according to the present invention comprises the step of exposure of a substrate to chemical vapour of at least one semiconductor precursor and at least one dopant element.
  • the substrate is further exposed to a hydrogen gas under constant flow in a reactor chamber.
  • the substrate is further exposed to the semiconductor precursor under pulse flow and exposed to the dopant element under constant flow.
  • dopant element and semiconductor precursor are both introduced under pulse flow, however the pulses of injection are alternating.
  • the method according to the present invention increases incorporation of dopant in semiconductor via controlling the flow of precursors in time to limit the unwanted cross reaction in the gas phase between the different precursors by the separation in time.
  • the precursors’ gas injection i.e. to pulse the injection of the precursors
  • An alternative technical effect of the method according to present invention is reduction of non-diamond (i.e. sp 2 -carbon) in deposited diamond layer by pulsing the carbon precursor gas. It is further provided increasing the active hydrogen species in the gas phase responsible for the etching of s p2 -carbon, or by pulsing the injection of oxygen gas that is also known to etch s p2 -carbon.
  • Flow is the volume of fluid that passes in a unit of time. Flow is often measured in units of standard cubic centimeters per minute (seem) in standard conditions for temperature and pressure of a given fluid. A skilled person knows the method how to measure the flow of the gas being introduced into the reaction chamber.
  • the semiconductor precursor is selected from the group of: methane, ethane, silane, Si 2 H 6 , GeH 4 .
  • the dopant element is selected from the group of:
  • - acceptor atoms such as boron, aluminium, gallium, indium
  • - donor atoms such as phosphorus, arsenic, antimony, bismuth; or
  • shape of the pulse of semiconductor precursor is squared, harmonics or sawtooth wave shapes.
  • the total gas flow is preferably between 200 and 2000 seem.
  • time period of the process is up to 30 min depending on the gas flow dynamic of the reactor, typically few minutes.
  • the duration of the gas injection is from 1 % - 50% of the time period of the process (duty cycle).
  • the second aspect of the present invention concerns a reactor for production of an extrinsic semiconductor.
  • the reactor is especially suitable for carrying out the method in accordance with the present invention.
  • the reactor comprises:
  • the holder is capable to hold a sample, wherein the sample is configured to receive plasma from a chemical vapour deposition system;
  • At least one gas injecting system capable to inject hydrogen gas, semiconductor precursor and dopant element into the vacuum chamber, wherein the gas injecting system is capable to inject the hydrogen gas at constant flow;
  • the reactor further comprises:
  • the gas activation system is microwave plasma enhanced chemical vapour deposition reactor.
  • Microwave plasma enhanced CVD reactor is more convenient to use compared to hot filament. Filaments need to be replaced regularly, the element of the filament can also contaminate the diamond layer. Yet, microwave plasma is limited in size, which is not the case for hot filament gas activation.
  • the gas activation system is hot filament chemical vapour deposition reactor.
  • a product obtainable by the method according to the present invention is disclosed.
  • the product is a layer of phosphorus doped diamond obtainable by the method according to the invention, wherein the phosphorus dopant concentration is higher than 2E20 phosphorus atoms I cm -3 .
  • the layer can have thickness from 10 nm to 100p.m.
  • the product can be used as a semiconductor used for electronics as source, drain in a transistor, or interlayer to form a low resistive ohmic contact in diamond-based diodes or transistors.
  • the product obtainable by the method according to the present invention can be used as working electrode, preferably working electrode in electrochemistry.
  • Fig. 1a represents optical emission spectra of PH and the variation of the intensity of the maximum line of the PH spectrum as a function of the added methane flow in hydrogen plasma.
  • Fig. 1 b represents optical emission spectra of PH and the variation of the intensity of the maximum line of the CH line as a function of the methane concentration in the gas phase.
  • Fig. 1c represents normalized intensity of the atomic phosphorus emission lines (213 nm and 253 nm), the PH line and the CH line as a function of the methane concentration in hydrogen plasma in a log-log scale.
  • Fig. 2a is time dependent variation of the H, at. P, PH and CH species light emission in pulsed injection of methane (1 min) over one period of time (5 min) at a concentration of phosphine in hydrogen of 6 E-6.
  • Fig. 2b Time dependent variation of the H, at. P, PH and CH species light emission in pulsed injection of methane (1 min) over one period of time (5 min) at concentration of phosphine in hydrogen of 1.2 E-3.
  • Fig. 2c schematically represents an embodiment, wherein the dopant element and semiconductor precursors are alternating in time periods.
  • Fig. 3a shows phosphorus concentration in diamond as function of the depth as measured by secondary ion mass spectroscopy depending on the flow of phosphine (continuous) in the reactor and the methane (pulse) injection mode.
  • Fig. 3b shows increase in the incorporation efficiency of the pulsed injection compared to the continuous injection of CH 4 methods and the phosphorus concentration in diamond as a function of the nominal ratio of PH 3 and CH 4 flow rate and the methane injection mode: continuous (black squares) or pulsed (red dots).
  • Fig. 4 shows comparison of the deposition rate of phosphorus doped diamond for continuous and pulsed methane injection.
  • Fig. 5 schematically represents a reactor for carrying out a method in accordance with the present invention.
  • Fig. 6 schematically represents a preferred embodiment of the rector according to present invention having enhanced pumping system.
  • Fig. 7 schematically represents a preferred embodiment of the reactor according to the present invention having injected system.
  • Fig. 8 schematically represents a preferred embodiment of the reactor according to the present invention having enhanced gas activation system.
  • Fig. 9 schematically represents a preferred embodiment of the reactor according to the present invention comprising all of the above-mentioned enhanced systems.
  • Fig. 1a represents the decreasing PH radical emission line intensity at constant concentration of phosphine gas with the increasing concentration of methane in the hydrogen plasma in a NIRIM type microwave plasma enhanced chemical vapour deposition system. Simultaneously, the CH radical emission line increases consistently with the methane concentration as shown in Fig. 1b.
  • Fig. 1c The disappearing of the PH radical and atomic phosphorus and the increasing CH concentrations in the plasma are summarized in Fig. 1c where are reported their respective emission line intensity with the increasing concentration of methane in the plasma.
  • Fig. 1a - 1c represents prior art solution for constant flow injection.
  • Figure 2a and 2b represents the time dependent evolution of the normalized light intensity of the emission wavelengths of the atomic hydrogen, CH radical, PH radical and atomic phosphorus (at. P) from an H 2 -CH 4 -PH 4 plasma in a NIRIM type microwave plasma enhanced chemical vapor deposition system over one period of time (5 mins) and a pulsed injection of methane of 1 min also illustrate the variation of the chemical species in the reactor due to chemical reaction between precursors. While the intensity of the hydrogen line remains nearly constant over the period of time, one can observe a clear simultaneous drop of the intensity of the PH and at. P emission lines to their background level with the addition of methane in the gas phase and the rise of the intensity of the CH radical emission line.
  • increase of the dopant in an extrinsic semiconductor can be provided by the exposure of a substrate by hydrogen gas at constant flow.
  • the pulses of the dopant element and semiconductor can be alternating, i.e. in a first time period ti a pulse of the dopant element is injected into a reaction chamber while the semiconductor precursor gas is not injected therein.
  • the step of injection is opposite, i.e. the dopant element is not injected into the reaction chamber while the semiconductor precursor is injected therein.
  • the alternation of the pulses is schematically shown in Fig. 2c.
  • the time periods h and t 2 can be 60 s.
  • Fig. 3a shows the in-depth chemical phosphorus concentration in a multilayer diamond sample prepared with different phosphorus concentrations/flows using either continuous or pulsed injection of methane in the reactor as measured by secondary ion mass spectroscopy.
  • Fig. 3b shows the higher incorporation of phosphorus in diamond using the pulsed injection of methane compared to the continuous injection.
  • the increase of phosphorus incorporation varies with the increasing ratio of the flow of PH 3 and CH (setting point for the methane when the flow is on).
  • the semiconductor precursor can be silicon or diamond, such as CVD diamond.
  • Example of dopant element can be boron, phosphorus or any other element from III B or V B column of periodic table of elements.
  • Fig. 4 represents a result of phosphorus dopant increase incorporated in diamond semiconductor precursor.
  • the results show (i) the logical lower deposition rate using the pulsed method due to the lower used amount of carbon precursor (1/5) and (ii) the faster drop of the growth rate in continuous injection mode compared to the pulsed injection mode.
  • the use of the pulse gas injection is not limited to the increase of dopant concentration, but it can be used for the reduction of non-diamond (i.e. sp 2 -carbon) in deposited diamond layer by pulsing the carbon precursor gas, i.e. that is equivalent to increasing the active hydrogen species in the gas phase responsible for the etching od sp 2 carbon, or by pulsing the injection of oxygen gas that is also known to etch sp 2 carbon.
  • FIG. 5 a gas activation system 6, a gas injecting system 7 and a pumping system 8 employed in a reactor 1 according to the invention is shown.
  • a vacuum chamber 2 is further employed in the reactor 1 in accordance with the present invention.
  • the vacuum chamber 2 contains a substrate holder 3 therein and a sample 4 positioned on the holder 3 as a skilled person in the art would normally use it.
  • the vacuum chamber 2 can communicate with other systems 6, 7, 8 as described in the present disclosure through gate valves.
  • a reaction space can be surrounded by collars made of stainless steel and/or an insulator so that excited reactant gas does not spread out to the inside of the structure and does not accumulate the product which can cause flakes to be present therein.
  • Gas injecting system 7 is configured to inject a semiconductor precursor and dopant gas in accordance with the present invention.
  • the gas activation system 6 is capable to active gasses to form a plasma 5 therefrom.
  • the gas activation system 6 is further configured to activate the gasses near to the sample 4 so that, desired chemical reactions are triggered nearby a resonance space.
  • the gas activation system 6 can be a microwave chemical vapour deposition system (MCVD) or plasma enhanced chemical vapour deposition system (PECVD).
  • MCVD microwave chemical vapour deposition system
  • PECVD plasma enhanced chemical vapour deposition system
  • the gas injecting system 7 is introducing the hydrogen gas into the reactor 1 at constant flow.
  • the gas injecting system 7 can introduce the gases of dopant element and semiconductor precursor in two regimes.
  • the dopant element is introduced at constant flow and semiconductor is introduced at pulsed flow, such as shown in Fig. 3a.
  • the gas injecting system 7 is configured to introduced the dopant element and semiconductor precursor in alternating pulses, such as shown in Fig. 2c.
  • the gas activation system 6 is configured to active the gasses and form plasma 5 from the gasses being presented at vacuum chamber 2 near to the sample 4 in the particular time.
  • the pump system 8 can be a turbomolecular pump used for pumping cycles. The pumping system 8 is used in order to minimize the system background gases, in particular the gasses that were present in the vacuum chamber in previous loop of the cycle.
  • non-reactive gas can be introduced into the reaction space into the vacuum chamber 2 through conduit a pipe.
  • the non-reactive gas can be activated via microwaves radiated into the resonance space from a microwave oscillator comprised in the gas activation system 6 through a window made of synthetic quartz.
  • Fig. 6 discloses a preferred embodiment of the reactor 1, wherein the pumping system 8 comprises at least three pumps, in particular a rotary oil pump 81 , a turbo-molecular pump 82 and a membrane pump 83.
  • the rotary oil pump 81 is connected to the vacuum chamber 2 through a first pipe wherein the first pipe comprises a valve 841 and throttle valve 842 serving for the selection of the pumping configuration valve 841 and the control of the pumping speed and therefor the pressure in the reactor.
  • the rotary oil pump 81 is also connected to the vacuum chamber 2 through a second pipe comprising a second valve 851. Gas is exhausted through the rotary oil pump 81.
  • the turbo molecular pump 82 is connected to the membrane pump 83 through a pipe comprising valve 862.
  • the turbomolecular pump 82 is connected to the second pipe connected to the vacuum chamber 2 through a valve 861. Gases can also be exhausted through a system of the turbomolecular pump 82 and the membrane pump 83.
  • the pumping system 8 as described above provides three pumping configurations to evacuate the system to a base pressure below 1 E-6 mbar via a first pumping using the rotary pump followed by the turbomolecular pumping to control the pressure in the reactor through the Throttle valve 842.
  • the embodiment may further comprise an optical window for optical scanning of the sample 4 positioned on the substrate holder 3 in close proximity of the plasma 5 created by a gas activation system 6.
  • Fig. 7 discloses a preferred embodiment of the reactor 1, wherein the gas injecting system 7 further comprises mass flow controllers 711 and valves 712 connected to gas sources 71 , 72, 73 and 74.
  • the gas source 74 is directly connected to a gas valve 741 without a mass controller.
  • Gas source 71 contains hydrogen and through mass flow controller 711 , which is used to control the flow rate of the gas from the gas source 71, the gas to the vacuum chamber. Any of the herewith disclosed mass flow controller 711 can advantageously maintain the flow rate of the gases at a setpoint value for a period of time before the flow rate begins to drop.
  • Gas source 72 contains the semiconductor gas precursor (usually methane for diamond deposition, silane for silicon).
  • Gas source 73 contains the dopant gas precursor.
  • Gas source 74 contains nitrogen, argon or air.
  • the gas source 74 is used to vent the reactor. All of the herewith described sources 71 72 73 74 are connected to the vacuum chamber 2 via gas valves 712, 741 which serves for isolation of the gas lines during the evacuation of the reactor and its base pressure prior to the semiconductor deposition.
  • the present embodiment of the reactor further comprises an optical window 21 for optical scanning a sample 4.
  • the reactor further comprises a vacuum chamber 2 which can be a quartz tube.
  • a substrate holder 3 is further provided to hold the sample 4 and in proximity of plasma 5 created by the gas activation system 6.
  • the pumping system 8 enables to evacuate gasses which are not desired to be present in the vacuum chamber.
  • Fig. 8 discloses a preferred embodiment of the reactor 1 , wherein the gas activation system 6 is microwave plasma enhanced CVD system.
  • the microwave CVD activation system, microwave electric discharge power 61 is directly introduced into the vacuum chamber 2 thereby causing glow discharge plasmas 5 in close proximity of the sample 4.
  • the waveguide 62 serves for the microwave controlled propagation.
  • the waveguide 62 is connected to sliding microwave short circuit 63 which serves for the adjustment of the plasma position in the reactor (quartz tube).
  • the embodiment further comprises a pumping system 8.
  • Fig. 9 discloses a preferred embodiment of the reactor 1 comprising all of the above- mentioned preferred embodiments according to Fig. 6, 7 and 8. Industrial applicability
  • the present invention can be used in the fabrication of diamond (silicon) unipolar and bipolar electronic devices in the formation of low contact resistivity ohmic contacts in diodes and transistor, or as drain and source in metal-oxide-semiconductor field effect transistor (MOSFET) for layers with atomic phosphorus concentration in diamond above 2E20 cm-3. They can be used also in the fabrication of electrochemical electrodes and electrochemical sensors.
  • diamond silicon
  • MOSFET metal-oxide-semiconductor field effect transistor

Abstract

The present invention relates to a method for an extrinsic semiconductor manufacturing by chemical vapour deposition. A substrate is exposed by at least one semiconductor precursor and at least one dopant element. The method comprises steps of: injecting a hydrogen gas at constant flow; and injecting a gas containing the dopant element to a reaction chamber under constant flow rate, and injecting gas of the semiconductor precursor under pulsed flow rate; or injecting the dopant element and the semiconductor precursor under pulse flow rate, wherein pulse of the dopant element and the semiconductor precursor are alternating. In another aspect, product capable to be produced by the method is disclosed. The product is a layer of phosphorus dopes diamond deposited on a substrate, characterized in the phosphorus dopant concentration is higher than 2E20 phosphorous / cm-3. In a third aspect, a reactor for carrying out the method is provided.

Description

A semiconductor having increased dopant concentration, a method of manufacturing thereof and a chemical reactor
Technical field
[001] The present invention pertains to material science, more particularly to semiconductor materials suitable for electronics and/or electrochemistry. In particular, the present invention relates to deposition of epitaxial layers or polycrystalline semiconductor layers with appropriate seeding pre-treatment, e.g. deposition of diamond seed, on a substrate.
[002] In a second aspect, the present invention relates to a method of doped semiconductor production, in particular via activated chemical vapour deposition, such as microwave plasma enhanced CVD or hot filament CVD methods.
[003] In yet another aspect, the present invention relates to a chemical reactor suitable for production such semiconductor suitable for electronics and/or electrochemical electrodes.
Background of the invention
[004] Diamond possesses physical and electrical properties such as high breakdown voltage, high thermal conductivity, small dielectric constant, wide band gap and excellent radiation hardness which qualifies its suitability for industrial application in high power electronics. Besides that, diamond is also chemically stable and is considered as a one of the biocompatible material. It is known, e.g. from WO2019042484, that diamond can be used as a part of chemically stable electrochemical electrodes, heat spreaders with extreme thermal conductivity, radiation hard particle physics detectors, and high frequency surface acoustic wave filters.
[005] Electrical properties of diamond are controlled by the addition of boron (p-type) and phosphorous (n-type) impurities. Diamond is also a unique material for quantum application with easily interrogable and controllable qubits at room temperature using the nitrogen vacancy or silicon vacancy defects. The key technology in the use of diamond for the fabrication of the next generation of quantum technologies and electronics is doping, i.e. the careful addition of impurities in diamond. Significant progresses have been achieved in the synthesis of doped diamond, yet the level of dopant incorporation remains limited depending on the substrate orientation, deposition conditions and the type of dopant (B, P, N, Si, Ge, etc.). In particular, the incorporation efficiency of phosphorus and nitrogen in diamond are known to be very low compared to the relatively easy boron incorporation. Various approaches for increased doping efficiency have been studied, for instance, use of off-axis surfaces or different crystalline orientations, and microwave plasma pulsing [1], However, these approaches have suffered from repeatability and reliability issues for phosphorus doping. Therefore, there is a need for new methods for increasing doping efficiency in diamond. [006] Artificial diamonds can be produced by at least two methods: (i) high pressure and high temperature method that reproduces the natural formation process of diamond and (ii) chemical vapor deposition (CVD) method. The CVD method is carried out in the gas phase at low pressure and high temperature. The diamond growth process uses activated vapor or gas of organic compounds (generally methane) as carbon precursor for the diamond growth. The carbon precursor is generally (but not limited) diluted in hydrogen at different concentrations. The vapor (or gas) of the dopant elements’ precursors are added in the gas mixture for the incorporation of the element during the growth process.
[007] There exists a large variety of CVD reactors for diamond deposition. They have in common a reaction cavity with different controlled precursor gas inputs, a pressure control system and a gas activation system. For the diamond growth to occurs, the gas mixture needs to be activated to produce the chemicals at the origin of the diamond growth and the incorporation of dopants. The gases activation is carried out either electrically by creating an electrical discharge (i.e. a plasma) using generally microwave energy or thermal energy using hot filaments. The temperature of the substrate is generally above 600 °C, although diamond deposition at temperature as low as room temperature has been reported. The substrates are either diamond crystals for epitaxial growth or pre-treated materials that can withstand the process parameters (high temperature, reactive atomic hydrogen species, etc.), i.e. silicon, SiO2, metals, etc. The diamond growth by CVD methods is directly related to the concentration of reactive species present in the gas phase. Although the exact process of diamond growth is not exactly known, it is acknowledged that atomic hydrogen (possibly halogen, e.g. chlorine) and CHX radical (with x < 3) present in the activated process gas are essential for the diamond growth. Although the mechanism of dopant incorporation is not fully understood, the dopant (B, P, N, Si, etc.) incorporation also results from the activated species present in the gas phase.
[008] The latest results show, see Fig. 1 , that atomic phosphorus and PH radical in the plasma of microwave plasma enhanced chemical vapor deposition systems are directly involved in the incorporation of phosphorus in diamond [2], These results also show the drop of the atomic phosphorus and the PH radical concentration with the minute addition of methane. This effect is attributed to the unwanted crossed chemical reactions between the carbon and phosphorus precursors’ radicals in the gas phase, which produce methinophosphide, which contributes to neither the phosphorus incorporation nor the diamond growth.
[009] The example, shown in Fig. 1 , represents unwanted cross-reactions in the gas phase that can result of the addition of the dopant precursor in process gas used for the growth of undoped diamond. In the particular case of phosphorus doping, these unwanted reactions severely limit the incorporation of phosphorus in diamond and decrease the deposition rate at high concentration of the phosphorus precursor as illustrated below. The cross-reactions between the carbon precursor and the dopant precursor is not limited to phosphorus doping. Previous studies describes the complex chemical reactions between activated mixture of PH3 or NH3 and CH for the understanding of the asthenosphere of Jovian planets [3]-[5] and report the formation of methylidynephosphane (HCP) and hydrogen cyanide (HCN), respectively [3], [4], Optical emission spectroscopy studies of plasmas used for diamond growth also report the presence of CN radical by the addition of nitrogen in the gas phase.
[010] US20170330746 discloses an apparatus and a method for manufacturing diamond electronic devices. The method comprises the step of positioning a substrate of diamond electronic device to a plasma enhanced chemical vapour deposition (PECVD) reactor, wherein the condition in the reactor is modulated, in particular controlling temperature of the substrate by manipulating microwave power, chamber pressure, and gas flow rates. In one embodiment, the modulation of temperature is above 600 °C and is pulsed. The pulsed variation of temperature is provided within 6 cycles in the range from 600 °C up to 1000 °C. According to the document, increase of dopant concentration in a diamond electronic device can be observed due to pulsed modulation of temperature. The flow rate of methane precursor, resp. phosphorus precursor is stable, i.e. there is a continues flow of both precursors.
[011] W00000677 relates to a method for doping semiconductor materials. One of the semiconductor materials is diamond. In view of the W00000677, an increased dopant concentration with nitrogen or boron can be observed according to a method disclosed therein. The method comprises steps of controlling of a dopant concentration introduced into an epitaxial film during CVD by controlling energy of dopant atoms impinged on the film. In an embodiment, the energy of dopant can be modulated via flow condition which can be continues or pulsed. However, when pulse regime was used, both precursors in a gas sources were introduced in pulsed regime simultaneously.
[012] US8017182 discloses a method for an epitaxy layer formation. The layers comprise metal and semi-metal oxides and nitrides deposited on a wafer substrate. The layers are deposited on the substrate using atomic layer deposition (ALD) method and chemical vapour deposition (CVD) method. Document further discloses combination of ALD and CVD in pulse regime.
Citation of non-patent literature
[1] F. A. Koeck, S. Chowdhury, and R. J. Nemanich, “Phosphorus incorporation for n-type doping of diamond with (100) and related surface orientation,” US 2017/0330746 A1 , Nov. 16, 2017.
[2] M. A. Lobaev, D. B. Radishev, A. M. Gorbachev, A. L. Vikharev, and M. N. Drozdov, “Investigation of Microwave Plasma during Diamond Doping by Phosphorus Using Optical Emission Spectroscopy,” Phys. Status Solidi A, vol. 216, no. 21 , p. 1900234, Nov. 2019, doi: 10.1002/pssa.201900234.
[3] J. P. Ferris, J. Y. Morimoto, R. Benson, and A. Bossard, “Photochemistry of NH3, CH4 and PH3. Possible applications to the Jovian planets,” Origins of Life, vol. 12, no. 3, pp. 261- 265, Sep. 1982, doi: 10.1007/BF00926895. [4] A. R. Bossard, R. Kamga, and F. Raulin, “Gas phase synthesis of organophosphorus compounds and the atmosphere of the giant planets,” Icarus, vol. 67, no. 2, pp. 305-324, Aug. 1986, doi: 10.1016/0019-1035(86)90111-9.
[5] A. Bossard, R. Kamga, and F. Raulin, “Quantitative gas chromatographic analysis of low- molecular-weight alkylphosphines in the presence of phosphine and hydrocarbons,” Journal of Chromatography A, vol. 330, pp. 400-402, Jan. 1985, doi: 10.1016/S0021- 9673(01)82003-3.
Summary of the invention
[013] In view of the prior art drawbacks, there is a need for a method for increasing dopant concentration in whole bulk of the semiconductor and thus increase doping efficiency of the CVD process in semiconductor materials such as silicon and more preferably diamond.
[014] In a first aspect, the present invention relates to a method of production an extrinsic semiconductor by chemical vapour deposition. In semiconductor production, doping is the intentional introduction of impurities into an intrinsic semiconductor for modulating its electrical, optical and structural properties. The doped material is referred to as an extrinsic semiconductor.
[015] The method according to the present invention comprises the step of exposure of a substrate to chemical vapour of at least one semiconductor precursor and at least one dopant element. The substrate is further exposed to a hydrogen gas under constant flow in a reactor chamber. In a first alternative, the substrate is further exposed to the semiconductor precursor under pulse flow and exposed to the dopant element under constant flow. Alternatively, dopant element and semiconductor precursor are both introduced under pulse flow, however the pulses of injection are alternating.
[016] The method according to the present invention increases incorporation of dopant in semiconductor via controlling the flow of precursors in time to limit the unwanted cross reaction in the gas phase between the different precursors by the separation in time. The precursors’ gas injection (i.e. to pulse the injection of the precursors) maximizes the concentration of active dopant precursor in the gas phase.
[017] An alternative technical effect of the method according to present invention is reduction of non-diamond (i.e. sp2-carbon) in deposited diamond layer by pulsing the carbon precursor gas. It is further provided increasing the active hydrogen species in the gas phase responsible for the etching of sp2-carbon, or by pulsing the injection of oxygen gas that is also known to etch sp2-carbon.
[018] Flow is the volume of fluid that passes in a unit of time. Flow is often measured in units of standard cubic centimeters per minute (seem) in standard conditions for temperature and pressure of a given fluid. A skilled person knows the method how to measure the flow of the gas being introduced into the reaction chamber. [019] In a preferred embodiment, the semiconductor precursor is selected from the group of: methane, ethane, silane, Si2H6, GeH4.
[020] In another preferred embodiment, the dopant element is selected from the group of:
- acceptor atoms such as boron, aluminium, gallium, indium; or
- donor atoms such as phosphorus, arsenic, antimony, bismuth; or
- or others elements as germanium, silicon, chromium, nickel, tin, cobalt, sulphur, gold and platinum.
[021] In another preferred embodiment, shape of the pulse of semiconductor precursor is squared, harmonics or sawtooth wave shapes.
[022] In another preferred embodiment, the total gas flow is preferably between 200 and 2000 seem.
[023] In yet another embodiment, time period of the process is up to 30 min depending on the gas flow dynamic of the reactor, typically few minutes. The duration of the gas injection is from 1 % - 50% of the time period of the process (duty cycle).
[024] The second aspect of the present invention concerns a reactor for production of an extrinsic semiconductor. The reactor is especially suitable for carrying out the method in accordance with the present invention.
[025] The reactor comprises:
- a vacuum chamber;
- a substrate holder inside the vacuum chamber, the holder is capable to hold a sample, wherein the sample is configured to receive plasma from a chemical vapour deposition system;
- at least one gas injecting system capable to inject hydrogen gas, semiconductor precursor and dopant element into the vacuum chamber, wherein the gas injecting system is capable to inject the hydrogen gas at constant flow; and
- inject the dopant element to the reactor under constant flow, and the semiconductor precursor under pulsed flow; or
- inject both, the dopant element and the semiconductor precursor under pulse flow rate, wherein pulse injection of the dopant element and the semiconductor precursor are alternating; and wherein the reactor further comprises:
- a pumping system capable to evacuate the gases from the reaction chamber; and
- gas activation system configured to activate the gases introduced by the gas introducing system to form reactive species for the doped semiconductor growth. [026] In a preferred embodiment, the gas activation system is microwave plasma enhanced chemical vapour deposition reactor. Microwave plasma enhanced CVD reactor is more convenient to use compared to hot filament. Filaments need to be replaced regularly, the element of the filament can also contaminate the diamond layer. Yet, microwave plasma is limited in size, which is not the case for hot filament gas activation.
[027] In another preferred embodiment, the gas activation system is hot filament chemical vapour deposition reactor.
[028] In a third aspect of the present invention, a product obtainable by the method according to the present invention is disclosed. The product is a layer of phosphorus doped diamond obtainable by the method according to the invention, wherein the phosphorus dopant concentration is higher than 2E20 phosphorus atoms I cm-3. The layer can have thickness from 10 nm to 100p.m.
[029] In another aspect of the present invention, the product can be used as a semiconductor used for electronics as source, drain in a transistor, or interlayer to form a low resistive ohmic contact in diamond-based diodes or transistors.
[030] In another aspect, the product obtainable by the method according to the present invention can be used as working electrode, preferably working electrode in electrochemistry.
Brief description of drawings
Fig. 1a represents optical emission spectra of PH and the variation of the intensity of the maximum line of the PH spectrum as a function of the added methane flow in hydrogen plasma.
Fig. 1 b represents optical emission spectra of PH and the variation of the intensity of the maximum line of the CH line as a function of the methane concentration in the gas phase.
Fig. 1c represents normalized intensity of the atomic phosphorus emission lines (213 nm and 253 nm), the PH line and the CH line as a function of the methane concentration in hydrogen plasma in a log-log scale.
Fig. 2a is time dependent variation of the H, at. P, PH and CH species light emission in pulsed injection of methane (1 min) over one period of time (5 min) at a concentration of phosphine in hydrogen of 6 E-6.
Fig. 2b Time dependent variation of the H, at. P, PH and CH species light emission in pulsed injection of methane (1 min) over one period of time (5 min) at concentration of phosphine in hydrogen of 1.2 E-3.
Fig. 2c schematically represents an embodiment, wherein the dopant element and semiconductor precursors are alternating in time periods. Fig. 3a shows phosphorus concentration in diamond as function of the depth as measured by secondary ion mass spectroscopy depending on the flow of phosphine (continuous) in the reactor and the methane (pulse) injection mode.
Fig. 3b shows increase in the incorporation efficiency of the pulsed injection compared to the continuous injection of CH4 methods and the phosphorus concentration in diamond as a function of the nominal ratio of PH3 and CH4 flow rate and the methane injection mode: continuous (black squares) or pulsed (red dots).
Fig. 4 shows comparison of the deposition rate of phosphorus doped diamond for continuous and pulsed methane injection.
Fig. 5 schematically represents a reactor for carrying out a method in accordance with the present invention.
Fig. 6 schematically represents a preferred embodiment of the rector according to present invention having enhanced pumping system.
Fig. 7 schematically represents a preferred embodiment of the reactor according to the present invention having injected system.
Fig. 8 schematically represents a preferred embodiment of the reactor according to the present invention having enhanced gas activation system.
Fig. 9 schematically represents a preferred embodiment of the reactor according to the present invention comprising all of the above-mentioned enhanced systems.
Detailed description of the preferred embodiments
[031] Fig. 1a represents the decreasing PH radical emission line intensity at constant concentration of phosphine gas with the increasing concentration of methane in the hydrogen plasma in a NIRIM type microwave plasma enhanced chemical vapour deposition system. Simultaneously, the CH radical emission line increases consistently with the methane concentration as shown in Fig. 1b. The disappearing of the PH radical and atomic phosphorus and the increasing CH concentrations in the plasma are summarized in Fig. 1c where are reported their respective emission line intensity with the increasing concentration of methane in the plasma. Fig. 1a - 1c represents prior art solution for constant flow injection.
[032] Figure 2a and 2b represents the time dependent evolution of the normalized light intensity of the emission wavelengths of the atomic hydrogen, CH radical, PH radical and atomic phosphorus (at. P) from an H2-CH4-PH4 plasma in a NIRIM type microwave plasma enhanced chemical vapor deposition system over one period of time (5 mins) and a pulsed injection of methane of 1 min also illustrate the variation of the chemical species in the reactor due to chemical reaction between precursors. While the intensity of the hydrogen line remains nearly constant over the period of time, one can observe a clear simultaneous drop of the intensity of the PH and at. P emission lines to their background level with the addition of methane in the gas phase and the rise of the intensity of the CH radical emission line. Once the flow of the methane is stopped, one can observe the simultaneous exponential 1- drop of the intensity of the CH radical emission line and 2- increase of the intensity of the PH and at. phosphorous emission lines. These exponential increase and decreases are function of the gas flow dynamic of the CVD reactor and dependent of the total gas flow and the reactor’s volume. One can also observe the lower amplitude of the CH line intensity due to these reactions in the gas phase at equivalent concentration of methane and phosphine. These figures show the possibility to control the concentration of the carbon and phosphorus radical in the reactor in time. This method has been used to test the incorporation of phosphorus in diamond depending on the continuous or pulsed flow of methane. The difference between examples of the method shown in Fig. 2a and 2b is concentration of precursors. In a first example, Fig. 2a, the concentration of precursor in hydrogen was 6 E-6. In an example according to Fig. 2b was 1.6 E-3.
[033] In an example, increase of the dopant in an extrinsic semiconductor can be provided by the exposure of a substrate by hydrogen gas at constant flow. The pulses of the dopant element and semiconductor can be alternating, i.e. in a first time period ti a pulse of the dopant element is injected into a reaction chamber while the semiconductor precursor gas is not injected therein. At the time period t2, the step of injection is opposite, i.e. the dopant element is not injected into the reaction chamber while the semiconductor precursor is injected therein. The alternation of the pulses is schematically shown in Fig. 2c. In some example, the time periods h and t2 can be 60 s.
[034] Fig. 3a shows the in-depth chemical phosphorus concentration in a multilayer diamond sample prepared with different phosphorus concentrations/flows using either continuous or pulsed injection of methane in the reactor as measured by secondary ion mass spectroscopy. One can observe the higher concentration of phosphorus in domains of pulsed methane injection in each interval of constant flow/concentration of phosphine.
[035] Fig. 3b shows the higher incorporation of phosphorus in diamond using the pulsed injection of methane compared to the continuous injection. The increase of phosphorus incorporation varies with the increasing ratio of the flow of PH3 and CH (setting point for the methane when the flow is on).
[036] In some embodiment, the semiconductor precursor can be silicon or diamond, such as CVD diamond. Example of dopant element can be boron, phosphorus or any other element from III B or V B column of periodic table of elements.
[037] Fig. 4 represents a result of phosphorus dopant increase incorporated in diamond semiconductor precursor. The results show (i) the logical lower deposition rate using the pulsed method due to the lower used amount of carbon precursor (1/5) and (ii) the faster drop of the growth rate in continuous injection mode compared to the pulsed injection mode. These results obtained by a simple control of only the injection of methane in the gas phase illustrate the technical effect of the method according to the present invention increasing the incorporation of dopant in diamond.
[038] The use of the pulse gas injection is not limited to the increase of dopant concentration, but it can be used for the reduction of non-diamond (i.e. sp2-carbon) in deposited diamond layer by pulsing the carbon precursor gas, i.e. that is equivalent to increasing the active hydrogen species in the gas phase responsible for the etching od sp2 carbon, or by pulsing the injection of oxygen gas that is also known to etch sp2 carbon.
[039] Referring to FIG. 5, a gas activation system 6, a gas injecting system 7 and a pumping system 8 employed in a reactor 1 according to the invention is shown. A vacuum chamber 2 is further employed in the reactor 1 in accordance with the present invention. The vacuum chamber 2 contains a substrate holder 3 therein and a sample 4 positioned on the holder 3 as a skilled person in the art would normally use it. The vacuum chamber 2 can communicate with other systems 6, 7, 8 as described in the present disclosure through gate valves. Between the gas injecting system 7 and pumping system 8, a reaction space can be surrounded by collars made of stainless steel and/or an insulator so that excited reactant gas does not spread out to the inside of the structure and does not accumulate the product which can cause flakes to be present therein. Gas injecting system 7 is configured to inject a semiconductor precursor and dopant gas in accordance with the present invention. The gas activation system 6 is capable to active gasses to form a plasma 5 therefrom. The gas activation system 6 is further configured to activate the gasses near to the sample 4 so that, desired chemical reactions are triggered nearby a resonance space. In some embodiment, the gas activation system 6 can be a microwave chemical vapour deposition system (MCVD) or plasma enhanced chemical vapour deposition system (PECVD). Besides the others, the gas injecting system 7 is introducing the hydrogen gas into the reactor 1 at constant flow. The gas injecting system 7 can introduce the gases of dopant element and semiconductor precursor in two regimes. In a first regime, the dopant element is introduced at constant flow and semiconductor is introduced at pulsed flow, such as shown in Fig. 3a. In a second regime, the gas injecting system 7 is configured to introduced the dopant element and semiconductor precursor in alternating pulses, such as shown in Fig. 2c. In both regime, the gas activation system 6 is configured to active the gasses and form plasma 5 from the gasses being presented at vacuum chamber 2 near to the sample 4 in the particular time. The pump system 8 can be a turbomolecular pump used for pumping cycles. The pumping system 8 is used in order to minimize the system background gases, in particular the gasses that were present in the vacuum chamber in previous loop of the cycle.
[040] As above suggested, non-reactive gas can be introduced into the reaction space into the vacuum chamber 2 through conduit a pipe. In some embodiments, the non-reactive gas can be activated via microwaves radiated into the resonance space from a microwave oscillator comprised in the gas activation system 6 through a window made of synthetic quartz.
[041] Fig. 6 discloses a preferred embodiment of the reactor 1, wherein the pumping system 8 comprises at least three pumps, in particular a rotary oil pump 81 , a turbo-molecular pump 82 and a membrane pump 83. The rotary oil pump 81 is connected to the vacuum chamber 2 through a first pipe wherein the first pipe comprises a valve 841 and throttle valve 842 serving for the selection of the pumping configuration valve 841 and the control of the pumping speed and therefor the pressure in the reactor. The rotary oil pump 81 is also connected to the vacuum chamber 2 through a second pipe comprising a second valve 851. Gas is exhausted through the rotary oil pump 81. The turbo molecular pump 82 is connected to the membrane pump 83 through a pipe comprising valve 862. The turbomolecular pump 82 is connected to the second pipe connected to the vacuum chamber 2 through a valve 861. Gases can also be exhausted through a system of the turbomolecular pump 82 and the membrane pump 83. The pumping system 8 as described above provides three pumping configurations to evacuate the system to a base pressure below 1 E-6 mbar via a first pumping using the rotary pump followed by the turbomolecular pumping to control the pressure in the reactor through the Throttle valve 842. The embodiment may further comprise an optical window for optical scanning of the sample 4 positioned on the substrate holder 3 in close proximity of the plasma 5 created by a gas activation system 6.
[042] Fig. 7 discloses a preferred embodiment of the reactor 1, wherein the gas injecting system 7 further comprises mass flow controllers 711 and valves 712 connected to gas sources 71 , 72, 73 and 74. The gas source 74 is directly connected to a gas valve 741 without a mass controller. Gas source 71 contains hydrogen and through mass flow controller 711 , which is used to control the flow rate of the gas from the gas source 71, the gas to the vacuum chamber. Any of the herewith disclosed mass flow controller 711 can advantageously maintain the flow rate of the gases at a setpoint value for a period of time before the flow rate begins to drop. Gas source 72 contains the semiconductor gas precursor (usually methane for diamond deposition, silane for silicon). Gas source 73 contains the dopant gas precursor. Gas source 74 contains nitrogen, argon or air. The gas source 74 is used to vent the reactor. All of the herewith described sources 71 72 73 74 are connected to the vacuum chamber 2 via gas valves 712, 741 which serves for isolation of the gas lines during the evacuation of the reactor and its base pressure prior to the semiconductor deposition. The present embodiment of the reactor further comprises an optical window 21 for optical scanning a sample 4. The reactor further comprises a vacuum chamber 2 which can be a quartz tube. A substrate holder 3 is further provided to hold the sample 4 and in proximity of plasma 5 created by the gas activation system 6. The pumping system 8 enables to evacuate gasses which are not desired to be present in the vacuum chamber.
[043] Fig. 8 discloses a preferred embodiment of the reactor 1 , wherein the gas activation system 6 is microwave plasma enhanced CVD system. The microwave CVD activation system, microwave electric discharge power 61 is directly introduced into the vacuum chamber 2 thereby causing glow discharge plasmas 5 in close proximity of the sample 4. The waveguide 62 serves for the microwave controlled propagation. The waveguide 62 is connected to sliding microwave short circuit 63 which serves for the adjustment of the plasma position in the reactor (quartz tube). The embodiment further comprises a pumping system 8.
[044] Fig. 9 discloses a preferred embodiment of the reactor 1 comprising all of the above- mentioned preferred embodiments according to Fig. 6, 7 and 8. Industrial applicability
[045] The present invention can be used in the fabrication of diamond (silicon) unipolar and bipolar electronic devices in the formation of low contact resistivity ohmic contacts in diodes and transistor, or as drain and source in metal-oxide-semiconductor field effect transistor (MOSFET) for layers with atomic phosphorus concentration in diamond above 2E20 cm-3. They can be used also in the fabrication of electrochemical electrodes and electrochemical sensors.

Claims

Claims
1. A method of an extrinsic semiconductor manufacturing by chemical vapour deposition, wherein a substrate is exposed to a semiconductor precursor and a dopant element, wherein the method is characterized in that, it further comprising:
- injecting hydrogen gas into a reactor chamber at constant flow; and
- injecting of the semiconductor precursor is pulsed flow injecting and injecting the dopant element under is constant flow injecting; or
- injecting of both, the dopant element and the semiconductor precursor are pulse flow, wherein pulse of the dopant element and the semiconductor precursor are alternating.
2. The method according to claim 1 , wherein the semiconductor precursor is selected from the group of: methane, ethane, silane, Si2H6, GeH4.
3. The method according to anyone of the preceding claims, wherein the dopant element is selected from the group of:
- acceptor atoms such as boron, aluminium, gallium, indium; or
- donor atoms such as phosphorus, arsenic, antimony, bismuth or lithium; or
- germanium, silicon, chromium, nickel, tin, cobalt, sulphur, gold and platinum.
4. The method according to anyone of the preceding claims, wherein shape of the pulse injection of the semiconductor precursor is harmonics or sawtooth wave shape.
5. The method according to anyone of the preceding claims, wherein total gas flow is below 2000 seem, preferably between 200 - 2000 seem.
6. The method according to anyone of the preceding claims, wherein the duration of the gas injection is 1 % - 50% of the time period.
7. The method according to anyone of the preceding claims, the time period of the gas injection is below 30 min, preferably between 1 - 5 min.
8. A reactor (1) for production of an extrinsic semiconductor wherein the reactor (1) comprises:
- a vacuum chamber (2); - a substrate holder (3) inside the vacuum chamber (2), the substrate holder (3) is capable to hold a sample (4), wherein the sample (4) is configured to receive plasma (5) from a chemical vapour deposition system;
- at least one gas injecting system (7) capable to inject hydrogen gas, semiconductor precursor and dopant element into the vacuum chamber, wherein the gas injecting system (7) is capable to inject the hydrogen gas at constant flow; and
- inject the dopant element to the reactor (1) under constant flow, and the semiconductor precursor under pulsed flow; or
- inject both, the dopant element and the semiconductor precursor under pulse flow rate, wherein pulse injection of the dopant element and the semiconductor precursor are alternating; and wherein the reactor further comprises:
- a pumping system (8) capable to evacuate the gases from the reaction chamber (2); and
- gas activation system (6) configured to activate the gases introduced by the gas injecting system (7) to form reactive species for the doped semiconductor growth. The rector (1) according to claim 8, wherein the gas activation system (6) is microwave plasma enhanced chemical vapour deposition reactor. The rector (1) according to claim 8, wherein the gas activation system (6) is hot filament chemical vapour deposition reactor. A layer of phosphorus doped diamond obtainable by the method according to anyone of the claims 1 - 6, wherein the phosphorus dopant concentration is higher than 220 dopant element I cm-3. Use of the layer according to claim 10 as a source or drain in a transistor or an interlayer to form an ohmic contact in a diamond-based diode or a transistor. An electrode comprising the layer according to claim 11 .
PCT/CZ2021/050154 2020-12-21 2021-12-20 A semiconductor having increased dopant concentration, a method of manufacturing thereof and a chemical reactor WO2022135627A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
LU102344A LU102344B1 (en) 2020-12-21 2020-12-21 A semiconductor having increased dopant concentration, a method of manufacturing thereof and a chemical reactor
LU102344 2020-12-21

Publications (1)

Publication Number Publication Date
WO2022135627A1 true WO2022135627A1 (en) 2022-06-30

Family

ID=74672383

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CZ2021/050154 WO2022135627A1 (en) 2020-12-21 2021-12-20 A semiconductor having increased dopant concentration, a method of manufacturing thereof and a chemical reactor

Country Status (2)

Country Link
LU (1) LU102344B1 (en)
WO (1) WO2022135627A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000000677A1 (en) 1998-06-26 2000-01-06 Extreme Devices, Inc. Method for doping semiconductor materials
US8017182B2 (en) 2007-06-21 2011-09-13 Asm International N.V. Method for depositing thin films by mixed pulsed CVD and ALD
US20170330746A1 (en) 2016-05-10 2017-11-16 Arizona Board Of Regents On Behalf Of Arizona State University Phosphorus incorporation for n-type doping of diamond with (100) and related surface orientation
WO2019042484A1 (en) 2017-08-29 2019-03-07 Fyzikalni Ustav Av Cr, V.V.I. Method of manufacturing a porous diamond layer and a nanofiber supported thick porous diamond layer

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000000677A1 (en) 1998-06-26 2000-01-06 Extreme Devices, Inc. Method for doping semiconductor materials
US8017182B2 (en) 2007-06-21 2011-09-13 Asm International N.V. Method for depositing thin films by mixed pulsed CVD and ALD
US20170330746A1 (en) 2016-05-10 2017-11-16 Arizona Board Of Regents On Behalf Of Arizona State University Phosphorus incorporation for n-type doping of diamond with (100) and related surface orientation
WO2019042484A1 (en) 2017-08-29 2019-03-07 Fyzikalni Ustav Av Cr, V.V.I. Method of manufacturing a porous diamond layer and a nanofiber supported thick porous diamond layer

Non-Patent Citations (9)

* Cited by examiner, † Cited by third party
Title
A. BOSSARD, R. KAMGAF. RAULIN: "Quantitative gas chromatographic analysis of low-molecular-weight alkylphosphines in the presence of phosphine and hydrocarbons", JOURNAL OF CHROMATOGRAPHY A, vol. 330, January 1985 (1985-01-01), pages 400 - 402, XP026557055, DOI: 10.1016/S0021-9673(01)82003-3
A. R. BOSSARDR. KAMGAF. RAULIN: "Gas phase synthesis of organophosphorus compounds and the atmosphere of the giant planets", ICARUS, vol. 67, no. 2, August 1986 (1986-08-01), pages 305 - 324
J. P. FERRISJ. Y. MORIMOTOR. BENSONA. BOSSARD: "Photochemistry of NH3, CH4 and PH3. Possible applications to the Jovian planets", ORIGINS OF LIFE, vol. 12, no. 3, September 1982 (1982-09-01), pages 261 - 265
KATO H ET AL: "Characterization of specific contact resistance on heavily phosphorus-doped diamond films", DIAMOND AND RELATED MATERIALS, ELSEVIER SCIENCE PUBLISHERS , AMSTERDAM, NL, vol. 18, no. 5-8, May 2009 (2009-05-01), pages 782 - 785, XP026155221, ISSN: 0925-9635, [retrieved on 20090213], DOI: 10.1016/J.DIAMOND.2009.01.033 *
KATO HIROMITSU ET AL: "Heavily phosphorus-doped nano-crystalline diamond electrode for thermionic emission application", DIAMOND AND RELATED MATERIALS, ELSEVIER SCIENCE PUBLISHERS , AMSTERDAM, NL, vol. 63, 11 August 2015 (2015-08-11), pages 165 - 168, XP029431728, ISSN: 0925-9635, DOI: 10.1016/J.DIAMOND.2015.08.002 *
KOIZUMI SATOSHI ET AL: "Phosphorus-doped chemical vapor deposition of diamond", DIAMOND AND RELATED MATERIALS, ELSEVIER SCIENCE PUBLISHERS , AMSTERDAM, NL, vol. 9, no. 3, 15 June 2017 (2017-06-15), pages 935 - 940, XP085073130, ISSN: 0925-9635, DOI: 10.1016/S0925-9635(00)00217-X *
LESKELÄ M ET AL: "4.05 - Atomic Layer Deposition", January 2014, COMPREHENSIVE MATERIALS PROCESSING, ELSEVIER, NL, PAGE(S) 101 - 123, ISBN: 978-0-08-096604-5, XP009516575 *
M. A. LOBAEVD. B. RADISHEVA. M. GORBACHEVA. L. VIKHAREVM. N. DROZDOV: "Investigation of Microwave Plasma during Diamond Doping by Phosphorus Using Optical Emission Spectroscopy", PHYS. STATUS SOLIDI A, vol. 216, no. 21, November 2019 (2019-11-01), pages 1900234
MACKUS ADRIAAN J. M. ET AL: "Synthesis of Doped, Ternary, and Quaternary Materials by Atomic Layer Deposition: A Review", CHEMISTRY OF MATERIALS, vol. 31, no. 4, 26 February 2019 (2019-02-26), US, pages 1142 - 1183, XP055830203, ISSN: 0897-4756, DOI: 10.1021/acs.chemmater.8b02878 *

Also Published As

Publication number Publication date
LU102344B1 (en) 2022-06-21

Similar Documents

Publication Publication Date Title
US6015459A (en) Method for doping semiconductor materials
EP0478984A1 (en) Plasma enhanced chemical vapor processing system using hollow cathode effect
Brodsky Plasma preparations of amorphous silicon films
CN111916341B (en) Gallium oxide thin film crystal growth method
JPH06196424A (en) Formation method of silicon carbide layer
Tokuda Homoepitaxial diamond growth by plasma-enhanced chemical vapor deposition
Oda et al. Hydrogen radical assisted chemical vapor deposition of ZnSe
Ohmagari et al. Growth and characterization of freestanding p+ diamond (100) substrates prepared by hot-filament chemical vapor deposition
LU102344B1 (en) A semiconductor having increased dopant concentration, a method of manufacturing thereof and a chemical reactor
JP2016113303A (en) Synthesis method of diamond thin film by microwave plasma cvd method
US7255744B2 (en) Low-resistivity n-type semiconductor diamond and method of its manufacture
US5903015A (en) Field effect transistor using diamond
GB2228949A (en) Silicon doped diamond films
JP5574126B2 (en) Heterogeneous element bond formation method
CN112877674A (en) Growth method of Sn-doped gallium oxide film material with accurately-controllable content
US5306660A (en) Technique for doping mercury cadmium telluride MOCVD grown crystalline materials using free radical transport of elemental indium and apparatus therefor
RU2624754C2 (en) Method for creating doped delta-layers in cvd diamond
Koizumi N-type diamond growth
WO2010082120A1 (en) Amorphous carbon, method of manufacturing the same, and solar cell including the same
JPH0428680B2 (en)
Giorgis et al. Growth, characterization, and physical properties of noncrystalline and nanostructured silicon-based alloys
US6113691A (en) Ultra-low pressure metal-organic vapor phase epitaxy (MOVPE) method of producing II-IV semiconductor compounds and II-VI semiconductor compounds thus produced
CN115074825A (en) Silicon carbide epitaxial structure, pulse type growth method and application thereof
Vlaskina et al. Properties of SiC on Si Substrate Films Obtained Using the Plasma‐Chemical Method
Sun et al. Growth direction, Sn content and crystallinity of Au-Sn catalyzed Ge1-xSnx nanowires

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 21844952

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 21844952

Country of ref document: EP

Kind code of ref document: A1