WO2018181642A1 - Procédé de formation de films de nitrure et d'oxyde, et appareil associé - Google Patents

Procédé de formation de films de nitrure et d'oxyde, et appareil associé Download PDF

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WO2018181642A1
WO2018181642A1 PCT/JP2018/013082 JP2018013082W WO2018181642A1 WO 2018181642 A1 WO2018181642 A1 WO 2018181642A1 JP 2018013082 W JP2018013082 W JP 2018013082W WO 2018181642 A1 WO2018181642 A1 WO 2018181642A1
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target
substrate
film forming
film
laser
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Japanese (ja)
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上田　大助
ロムアルド アレハンドロ フェレーラ
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国立大学法人京都工芸繊維大学
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    • 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
    • H01L21/02538—Group 13/15 materials
    • H01L21/0254—Nitrides
    • 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
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • 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
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C23C14/08—Oxides
    • 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
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/24—Vacuum evaporation
    • C23C14/28—Vacuum evaporation by wave energy or particle radiation
    • 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
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
    • H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
    • H01L21/02123—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon
    • H01L21/02164—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material being a silicon oxide, e.g. SiO2
    • H—ELECTRICITY
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    • 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
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
    • H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
    • H01L21/02123—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon
    • H01L21/0217—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz
    • H—ELECTRICITY
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    • 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
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
    • H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
    • H01L21/02172—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing at least one metal element, e.g. metal oxides, metal nitrides, metal oxynitrides or metal carbides
    • 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
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
    • H01L21/0226—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process
    • H01L21/02263—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase
    • H01L21/02266—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by physical ablation of a target, e.g. sputtering, reactive sputtering, physical vapour deposition or pulsed laser deposition
    • H—ELECTRICITY
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    • 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
    • H01L21/02576—N-type
    • H—ELECTRICITY
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    • 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
    • H01L21/02631—Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation

Definitions

  • the present invention relates to a nitride and oxide film forming method and film forming apparatus, and more particularly to a film forming method and film forming apparatus for forming a nitride and an oxide on a group III nitride semiconductor substrate.
  • MBE Molecular Beam Epitaxy
  • the PLD method is a method in which a surface of a target made of a film forming material is irradiated with a short pulse laser beam (pulsed laser beam), the material is evaporated (ablated), and a film is formed on a substrate.
  • a short pulse laser beam of about picosecond or less
  • the material can be evaporated before the thermal energy diffuses to the deep part of the target. That is, short pulse laser light can evaporate the material without heating the target.
  • Patent Document 1 discloses a method for forming a group III nitride by using a Ga group III metal as a target in an ammonia or nitrogen radical atmosphere.
  • Patent Document 2 discloses a method for forming a group III nitride on a sapphire nitride substrate by a PLD method.
  • the conventional research is mainly related to the improvement of crystallinity of a group III nitride semiconductor to be formed.
  • the conventional research is mainly related to the improvement of crystallinity of a group III nitride semiconductor to be formed.
  • no study has been made on the influence on the underlying group III nitride semiconductor.
  • an FET field effect transistor
  • the interface state between the GaN surface on which the channel is formed and the gate insulating film has a great influence on the characteristics of the FET, and the drive current and response speed of the FET are degraded.
  • the contact resistance (contact resistance) between the contact electrode and the GaN surface is affected by the crystallinity of the GaN surface in contact with the contact electrode, and may increase the contact resistance.
  • the target surface is irradiated with a laser to evaporate the material, and thus the material evaporates from a local region (spot) irradiated with the laser. Therefore, there is a problem that it is difficult to form a film having a uniform thickness on a large-diameter substrate.
  • the present invention provides a method for forming a nitride, an oxide, or an oxynitride on a group III nitride semiconductor by performing regrowth and formation of nitride, oxide, or oxynitride that can obtain good electrical characteristics.
  • An object is to provide a film forming apparatus.
  • the film forming method according to the present invention includes a first step of heating a surface of a substrate having a group III nitride while irradiating the surface of the substrate with nitrogen radicals, and after the first step, And a second step of forming a film on the surface of the substrate.
  • the film forming method according to the present invention is characterized in that, in the second step, the surface of a target made of a film forming material is irradiated with a laser beam in a pulsed manner to deposit the film forming material on the substrate. To do.
  • the substrate in the second step, is nitrided with nitrogen radicals, oxygen radicals, or a mixture of nitrogen radicals and oxygen radicals while irradiating the surface of the substrate.
  • nitrogen radicals oxygen radicals
  • oxygen radicals or a mixture of nitrogen radicals and oxygen radicals while irradiating the surface of the substrate.
  • the reactivity with nitrogen radicals and oxygen radicals supplied to the substrate surface is controlled while adjusting the film formation rate by controlling the frequency of the laser light in the PLD method, and the quality is high.
  • a film can be formed.
  • the film forming method according to the present invention is characterized in that the laser beam applied to the target surface is a laser beam optically branched into a plurality.
  • a film forming apparatus includes a substrate supporting apparatus that supports a substrate that is a film forming target, a substrate heating apparatus that heats the substrate, a target container that stores a target made of a film forming material, and the target container.
  • a target support device for supporting, a radical irradiation device, and a laser irradiation device;
  • the radical irradiation apparatus generates nitrogen radicals and supplies nitrogen radicals to the surface of the substrate,
  • the laser irradiation apparatus irradiates the target surface with pulsed laser light.
  • the film forming apparatus is characterized in that an optical element that divides a laser beam into a plurality of parts is provided between the laser irradiation apparatus and the target.
  • the laser beam is optically branched by the optical element in this way, it is not necessary to provide a complicated device such as a substrate revolving device or a laser scanning device in the PLD device.
  • a complicated device such as a substrate revolving device or a laser scanning device in the PLD device.
  • the film thickness to be formed can be improved evenly by simply rotating the substrate. Can do. Therefore, film thickness uniformity can be realized with a simple apparatus configuration.
  • the film forming apparatus according to the present invention is characterized in that an unevenness is provided on a wall surface where the target container is in contact with the target.
  • the film forming apparatus is characterized in that a wall surface of the target container in contact with the target is made of a substance having poor wettability with a film forming material constituting the target.
  • the target support device in the film forming apparatus according to the present invention is characterized in that the target container can be swung or rotated.
  • FIG. 1 is a conceptual diagram of a film forming apparatus according to a first embodiment of the present invention.
  • the schematic diagram explaining the function of the optical element which branches a laser beam into plurality.
  • Sectional drawing which illustrates typically the film-forming method by the branched laser beam.
  • the conceptual diagram explaining the principle which film thickness uniformity improves.
  • the graph which shows the transistor characteristic of insulated gate FET.
  • the top view and sectional drawing which show the modification of a target container.
  • GaN is exemplified as a typical group III nitride semiconductor, but is not limited to GaN.
  • a mixed crystal of InN, GaN, AlN, BN, etc. is also included in the group III nitride semiconductor.
  • FIG. 1 is a conceptual diagram showing the main configuration of the PLD apparatus.
  • the PLD apparatus includes a substrate support device 2 and a target support device 3 inside a chamber 1 that is an airtight vacuum vessel.
  • a substrate 4 as an object for forming a film is placed on the substrate support apparatus 2, a substrate 4 as an object for forming a film is placed.
  • the substrate 4 is exemplified by a circular wafer having a GaN layer on the surface, but is not limited thereto.
  • the substrate support device 2 can maintain the substrate 4 at a constant temperature by heating the substrate 4 to 200 [° C.] or higher by a built-in heating device.
  • the heating device may be a method of heating by heat conduction from a heater that generates Joule heat or a method of heating by radiant heat such as a lamp.
  • a target container 5a is supported on the target support device 3.
  • the target container 5a stores a target 6a that is a film forming material. Therefore, the target support device 3 supports the target 6a via the target container 5a.
  • the target support device 3 includes a temperature control device. Therefore, the target support device 3 can maintain the temperature of the target 6a at a constant temperature via the target container 5a.
  • the temperature control device may include a heating device, and may be configured to heat the target 6a to a melting point or higher so that the target 6a can be used as a liquid target.
  • the temperature control device may include a cooling device such as a Peltier element or a heat exchanger, and may be configured to suppress the temperature rise of the target due to laser light.
  • both a heating device and a cooling device may be provided so that advanced temperature control is possible.
  • a target material when epitaxially growing an n-type doped group III nitride, a target material may be Ga, Al, In alone or an alloy with Ge added in an amount of 0.5 to 5 [mol%]
  • Mg or 0.5 to 5 mol% of the target material alone or an alloy can be used.
  • oxide targets such as Si and NiO and C12A7
  • FIG. 1 shows an example in which different targets 6a and 6b are stored in two target containers 5a and 5b, respectively.
  • the target container 5a or the target container 5b can be selected according to the material to be deposited, supported by the target support device 3, and kept at a constant temperature. Therefore, it is possible to continuously form a plurality of different types of films.
  • the number of target containers is not limited to two, but may be more or one.
  • the chamber 1 includes a light transmission window 7 for introducing laser light.
  • the pulsed laser emitted from the laser irradiation device 8 installed outside the chamber 1 is collected by the lens 9, introduced into the chamber 1 through the light transmission window 7, and irradiated onto the target 6a.
  • the frequency of the laser pulse is set to be equal to or higher than a threshold of a repetition frequency that can maintain continuous excitation on the film forming material on the surface of the target 6a.
  • the center wavelength of the pulsed laser, the energy of one pulse, and the pulse width can be, for example, on the order of 1064 [nm], 50 [ ⁇ J], and picoseconds, but are not limited thereto.
  • the laser irradiation area (spot) diameter on the target 6a is focused to, for example, 100 [ ⁇ m] or less, but is not limited thereto.
  • This PLD apparatus includes a diffractive optical element (DOE) between the laser irradiation device 8 and the lens 9, and the diffractive optical element 10 divides the laser light into a plurality of parts.
  • the branched laser light is collected by the lens 9.
  • FIG. 2 is a schematic diagram showing branching of the laser light by the diffractive optical element 10 and condensing of the laser light by the lens 9.
  • the laser beam 101 emitted from the laser irradiation device 8 is branched into a plurality of laser beams 102 by the diffractive optical element 10.
  • the branched laser beam 102 is condensed on the surface of the target 6 a by the lens 9.
  • the condensed laser beam 103 irradiates the surface of the target 6a and supplies light energy.
  • a commercially available diffractive optical element can be used as the diffractive optical element.
  • An F- ⁇ lens (telecentric F- ⁇ lens or non-telecentric F- ⁇ lens) is used as the lens 9 for condensing the branched laser beam.
  • each laser beam is incident on the surface of the target 6a at the same angle regardless of the position on the surface of the target 6a.
  • the branched laser beams can obtain the same spot shape on the surface of the target 6a, and the same energy per unit area can be supplied to a plurality of irradiated regions.
  • the lens 9 is a non-telecentric F ⁇ lens, the laser beam spreads, so that the region larger than the light transmission window 7 can be irradiated with the laser beam. Since the distance from the light transmission window 7 to the target 6a is sufficiently longer than the diameter of the target 6a, the branched laser light can be regarded as being incident on the surface of the target 6a at substantially the same angle.
  • the multi-branch irradiation that divides the laser beam into a plurality of parts can improve the film thickness distribution (film thickness uniformity) formed on the substrate 4 as described later.
  • a diffractive optical element is used as an optical element for branching laser light.
  • a so-called microlens in which minute lenses are arranged in a specific pattern after the beam diameter of the laser light is expanded by a beam expander.
  • the laser beam may be branched using an array.
  • each lens can be used as a condensing lens together with a laser branch.
  • the film forming material evaporates at the portion irradiated with the laser beam on the surface of the target 6a.
  • the film forming material released from the surface of the target 6 a forms a plume 11, and a film is formed by the film forming material that has reached the opposing substrate 4.
  • the chamber 1 includes a gas introduction port 12 and an exhaust port 13, and pressure control and atmosphere control are possible.
  • a vacuum pump is connected to the exhaust port 13 so that the inside of the chamber 1 can be exhausted and kept in a vacuum state.
  • the pressure inside the chamber 1 can be kept constant by controlling the opening degree of an APC (Auto Pressure Controller) valve installed between the exhaust port 13 and the vacuum pump and the rotation speed of the vacuum pump.
  • APC Automatic Pressure Controller
  • this apparatus has a load lock chamber for substrate replacement in order to prevent unnecessary oxidation of the target surface, and a turbo molecular pump is used for exhausting the film formation chamber 1 to provide base pressure.
  • a turbo molecular pump is used for exhausting the film formation chamber 1 to provide base pressure.
  • the nitrogen gas to be used is a high-purity gas corresponding to a semiconductor.
  • a gas purifier is used, and a gas having an oxygen concentration of 1 [ppb] or less is particularly preferably used.
  • the chamber 1 is provided with a radical irradiation device 14, for example, a radical gun.
  • the radical irradiation device 14 is supplied with nitrogen gas whose flow rate is controlled by an MFC (mass flow controller), for example, 2 [sccm] nitrogen (N 2 ) gas, and is supplied with high frequency power, for example, 13.56 [MHz]. .
  • the radical irradiation device 14 generates nitrogen radicals 18 from nitrogen gas by the supplied power energy, and irradiates the generated nitrogen radicals 18 on the surface of the substrate 4 from the nozzle 15 which is an outlet. Since nitrogen radicals are active, they have a nitriding action on the surface of the substrate 4 and the film forming material that has come from the target 6 a to the substrate 4. Note that the frequency of the applied power is not limited to the above.
  • the amount of film forming material released from the surface of the target 6a has an angular distribution depending on the angle ⁇ formed with the direction perpendicular to the surface of the target 6a (normal direction).
  • the angular distribution of the emission amount is maximized in the vertical direction, that is, in the direction where ⁇ is zero, and is zero (zero) in the horizontal direction, that is, ⁇ is 90 °.
  • the angular distribution of the discharge amount can be approximated by a cosine law, that is, an expression proportional to the nth power of cos ⁇ . (Normally n is a value of 1 or more.)
  • the film forming material having the angular distribution is emitted. For this reason, the film formation speed is highest at the intersection between the normal of the spot surface irradiated with the laser and the surface of the substrate 4, and the film formation speed decreases as the distance from the intersection increases.
  • the film formed on the substrate 4 is thicker at the central part and thinner at the outer peripheral part. Accordingly, as the size of the substrate 4 increases, the film thickness difference between the central portion and the outer peripheral portion increases.
  • FIG. 3 is a cross-sectional view schematically illustrating a situation in which a plurality of plumes are emitted from the surface of the target 6a by a laser beam branched into a plurality.
  • the laser light 103a, 103b, 103c branched into a plurality by the diffractive optical element 10 is irradiated to a plurality of spots (spots) on the surface of the target 6a.
  • Plumes 11a, 11b, and 11c of the film forming material are emitted from the plurality of spots irradiated with the laser light.
  • the generation location of the plume is determined by the irradiation position of the laser beam, and the irradiation position of the laser beam can be determined by the diffractive optical element 10 and the lens 9.
  • FIG. 4 shows a conceptual diagram when a film is formed on the substrate 4 by the plume 11.
  • FIG. 4A shows an example in which a film is formed on the substrate 4 by one plume
  • FIG. 4B shows an example in which a film is formed on the substrate 4 by nine plumes.
  • the plume generation points formed on the target 6a are arranged concentrically so as to surround the center and the center.
  • the film is formed around the region 16 in the central portion of the substrate 4 by one plume. Therefore, the film thickness is the thickest in the region 16 and gradually approaches the outer peripheral portion. The film thickness decreases.
  • the nine plumes are used to center the region 16a of the central portion of the substrate 4 and the regions 16b, 16c, 16d, 16e, 16f, 16g, 16h, and 16i of the outer peripheral portion. Since the film is formed, the film thickness at the outer peripheral portion is prevented from being reduced, and the film thickness is improved.
  • the regions 16 and 16a and the like conceptually indicate the regions where the film thickness is the thickest for the sake of explanation, and do not indicate that the film is formed only in these regions.
  • the number of branches is not limited to nine.
  • the number and arrangement of the laser branches by the diffractive optical element 10 may be determined from the requirements for the film thickness distribution (film thickness uniformity) formed on the substrate 4.
  • the film thickness distribution can be predicted by actually measuring the film thickness distribution data emitted from one central position on the surface of the target 6a and superimposing the actual measurement data. That is, first, the film thickness distribution data emitted from one irradiation spot on the target surface is actually measured with a laser beam that does not branch. Next, the actually measured film thickness distribution data is applied to each irradiation spot of the laser beam branched into a plurality, and these film thickness distributions are added together to obtain the entire film thickness distribution on the substrate 4. Alternatively, assuming that the distribution function emitted from the laser spot is proportional to the power n of cos ⁇ , the power n and the proportionality coefficient are calculated from the actually measured data of the film thickness distribution emitted from one irradiation spot. Next, the film thickness distribution can be obtained by applying the obtained distribution function to the angular distribution emitted from each irradiation spot of the laser beam branched into a plurality and integrating at the surface position of the substrate 4.
  • the laser by the diffractive optical element 10 is adapted to the requirements of the size of the substrate 4, the film thickness uniformity, the growth rate, and the processing capability (throughput) of the apparatus.
  • the light branching pattern can be determined.
  • various requirements can be met by exchanging the diffractive optical element 10.
  • the laser beam is branched so as to be arranged in a straight line, the film forming material is ablated from the irradiation spot arranged in a straight line on the target surface, and the substrate 4 is simply rotated (not revolved).
  • the film thickness uniformity can be improved. That is, film thickness uniformity can be realized with a simple apparatus configuration in which a mechanism for rotating the substrate 4, such as an electric motor, is provided in the substrate support device 2.
  • the substrate 4 supported by the substrate support device 2 is heated to a predetermined temperature of, for example, 200 [° C.] or higher by a heating device built in the substrate support device 2.
  • the method for heating the substrate 4 is, for example, a method in which the substrate 4 is placed on the substrate support device 2 held at a constant temperature and heated by heat conduction from the substrate support device 2, and after the substrate 4 is placed on the substrate support device 2, There is a method of increasing the temperature of the substrate support device 2 and heating it by heat conduction, or a method of irradiating the back surface of the substrate 4 from the substrate support device 2 side with a lamp and heating the substrate 4 by radiant heat. Any of the above methods may be used as the heating method, and the method is not limited to the above.
  • the radical irradiation device 14 irradiates the surface of the substrate 4 with nitrogen radicals.
  • the nitrogen radical has an effect of nitriding the surface of the substrate 4.
  • the nitrogen vacancies can be reduced by supplying active nitrogen to the nitrogen vacancies from which nitrogen has been removed from the surface.
  • Heating the substrate 4 can promote thermal diffusion into the GaN layer near the surface with nitrogen radicals, and can increase the reactivity of the nitrogen radicals with nitrogen vacancies.
  • crystal defects may occur in the GaN layer in a manufacturing process of an electronic device using a group III nitride semiconductor, for example, plasma processing such as dry etching or ion implantation.
  • Such crystal defects existing in the GaN layer can be recovered by performing a heat treatment, for example, 200 [° C.] or higher while irradiating nitrogen radicals.
  • a heat treatment for example, 200 [° C.] or higher while irradiating nitrogen radicals.
  • Nitrogen radicals may be irradiated after reaching a predetermined temperature, but the temperature can be raised while irradiating the nitrogen radicals and kept at the predetermined temperature to effectively prevent nitrogen desorption at the time of temperature increase. .
  • the substrate 4 may be supported on the substrate support device 2 and the substrate 4 may be irradiated with nitrogen radicals from the radical irradiation device 14 until the substrate 4 reaches a predetermined temperature.
  • the pulsed laser light emitted from the laser irradiation device 8 is branched into a plurality of parts by a diffractive optical element 10 which is an optical branching device of the laser light, and then condensed by a lens 9 and passes through a light transmission window 7. Then, the surface of the target 6a is irradiated.
  • a diffractive optical element 10 which is an optical branching device of the laser light
  • a lens 9 passes through a light transmission window 7.
  • the surface of the target 6a is irradiated.
  • the pulsed laser light for example, nanosecond pulse, picosecond pulse, or femtosecond pulse laser light can be used.
  • the material of the target 6a evaporates and is emitted toward the opposing substrate 4.
  • the growth rate of the film formed on the substrate 4 depends on the repetition frequency at which the laser light is emitted. When the repetition frequency becomes equal to or higher than the threshold value, the film formation rate starts to increase.
  • the center wavelength of the laser is 1064 [nm]
  • the pulse width is 24 [ps] (picoseconds)
  • the fluence is 1.1 [J / cm 2 ].
  • the pulse width of the short pulse laser is preferably picoseconds. If the energy of one laser pulse is too high, unevenness may occur on the target.
  • the film formation rate can be controlled by the energy (fluence) of the laser, but the film formation rate can be adjusted with high accuracy by adjusting the repetition frequency. Thereby, reaction with the nitrogen radical and oxygen radical supplied from the radical irradiation apparatus 14 can be adjusted.
  • the target 6a may be solid, but the Ge-doped Ga having a stable concentration can be evaporated by heating and liquefying above the melting point.
  • the film forming material is evaporated from the surface of the target 6a to the surface of the substrate 4 by laser light, and for example, when forming a nitride, the radical irradiation device 14 irradiates the surface of the substrate 4 with nitrogen radicals.
  • the film forming material evaporated from the surface of the target 6 a reacts with the nitrogen radicals to form a nitride, for example, a Ge-doped GaN film.
  • the nitriding reaction can be promoted by heating the substrate 4 to, for example, 200 [° C.] or higher.
  • the laser light is branched into a plurality of parts by the diffractive optical element 10 and irradiated onto the target 6a in accordance with the requirements for the size and film thickness uniformity of the substrate 4. Since the energy of the laser light is dispersed according to the number of branches, the repetition frequency depends on the number of branches.
  • Si silicon
  • Si silicon
  • Si may be evaporated by laser light, and reacted with nitrogen radicals on the surface of the substrate 4 to form a silicon nitride film.
  • the target container 5b containing the target 6b made of Si and the target container 5a are exchanged, and the target support device 3
  • the target container 5a may be supported by irradiating the target 6b with laser light to form a silicon nitride film on the GaN film.
  • Oxygen gas is supplied to the radical irradiation device 14 to irradiate oxygen radicals. Oxygen radicals supplied to the surface of the substrate 4 react with the film forming material evaporated from the target 6a to form an oxide.
  • a nitride such as a metal or an oxide can be formed by reacting with a substance such as a metal other than silicon and nitrogen or oxygen.
  • an evaporated film forming material to the surface of the substrate 4 and simultaneously supply nitrogen radicals and oxygen radicals together to form an oxynitride such as SiON.
  • the film forming method of the present embodiment can be advantageously applied to, for example, a gate insulating film of FET or a contact electrode to the source / drain region as described below.
  • the gate insulating film When a gate insulating film is formed on a channel region of a group III nitride semiconductor such as GaN, the gate insulating film can be formed while preventing generation of defects due to nitrogen desorption and recovery of the defects. Therefore, generation of unnecessary interface states can be prevented, and FET performance can be improved and variation can be suppressed.
  • the heating process while irradiating nitrogen radicals and the film forming process by the PLD method were performed in the same chamber, but each was performed in different chambers, and the substrate was separated between the different chambers by a vacuum transfer device. 4 may be transferred.
  • the apparatus used for the process of heating while irradiating nitrogen radicals the target 6a, the target container 5a, and the target support apparatus 3 are unnecessary, and the laser irradiation apparatus 8 that irradiates the target surface with laser light is unnecessary. is there.
  • a configuration in which laser light is used to heat the substrate 4 from the surface may be employed.
  • MOCVD is used on sapphire or silicon to continuously epitaxially grow a GaN layer of 1 [ ⁇ m] and an Al 0.2 Ga 0.8 N layer of 20 [nm], and then about 800 [° C.].
  • a substrate subjected to the high-temperature treatment was prepared.
  • the substrate is irradiated with nitrogen radicals at room temperature, sample A having a silicon nitride film of 20 [nm] formed by a PLD method using silicon as a target, and heated to 200 [° C.] while irradiating nitrogen radicals.
  • Sample B in which a silicon nitride film was formed to 20 [nm] by PLD method using silicon as a target was produced.
  • a gate electrode was formed on the channel region by depositing 20 nm thick Ni and 200 nm thick Au on the two types of samples A and B and patterning them by the lift-off method. . Thereafter, the silicon nitride film is removed by a combination of lithography and dry etching using, for example, CF 4 so that the substrate surface serving as the source and drain regions is exposed. Next, Ti with a thickness of 20 [nm] and Al with a thickness of 200 [nm] are vapor-deposited and patterned by a lift-off method to form contact electrodes on the regions to be the source and drain. Thereafter, heat treatment was performed at about 500 [° C.] in a nitrogen atmosphere to obtain ohmic contact between the contact electrode and the source and drain regions of the substrate.
  • FIG. 5 shows the transistor characteristics of an FET in which a silicon nitride film is formed as a gate insulating film on a Ga nitride semiconductor substrate by this device, and the change in drain current (Id ⁇ Vg when the gate voltage is boosted or lowered). Characteristic).
  • FIGS. 5A and 5B show the transistor characteristics of Sample A and Sample B, respectively.
  • FIG. 5A there is a clear difference in drain current between when the gate voltage is raised and when it is lowered, and hysteresis is observed in the Id-Vg characteristic.
  • FIG. 5B no hysteresis is observed in the Id-Vg characteristic.
  • the substrate by heating the substrate at 200 [° C.] while irradiating nitrogen radicals, the interface state between the surface of the Ga nitride semiconductor substrate and the silicon nitride film as the gate insulating film is reduced. It was verified that transistor characteristics were obtained. Further, it can be understood from the dependence of the substrate heating temperature that the nitrogen radicals promote the recovery of the group III nitride defects by heating the substrate to 200 [° C.] or higher.
  • FIG. 6 shows a modification of the target container 5a.
  • FIGS. 6 (a) and 6 (b) are top views of the target container 5a for accommodating the target 6a
  • FIG. 6 (c) is a cross-sectional view of the target container 5a.
  • the target 6 a accommodated (held) in the target container 5 a can be heated by the target support device 3.
  • the target 6a By heating and holding the target 6a at a temperature equal to or higher than the melting point, the target 6a can be used as a liquid target.
  • the target container 5a is used as a crucible.
  • a liquid target is used in the PLD method
  • oxynitride or the like may precipitate (or aggregate) as slag on the surface of the target 6a due to surface tension.
  • this slag (precipitate) is irradiated with laser light, the purity of the film deposited on the substrate 4 may be deteriorated.
  • a method for preventing the deterioration of the purity of the film due to the slag will be described.
  • This slag floats on the surface of the target 6a due to thermal energy and moves.
  • This slag By constraining this slag outside the laser light irradiation region, it is possible to prevent vapor deposition from the slag and to prevent deterioration of the purity of the formed film.
  • a groove is formed on the inner wall of the target container 5a.
  • the contact area between the target 6a and the inner wall of the target container 5a can be increased. it can.
  • the surface tension of the target 6a acts to reduce the contact portion with the inner wall of the target container 5a, and further swings the target 6a.
  • the outer edge of the target 6a becomes circular and is separated from the concave portion of the inner wall of the target container 5a.
  • the slag 7 on the surface of the target 6a moves to the concave portion of the inner wall.
  • the slag 7 is excluded from the surface of the target 6a irradiated with the laser light, and the surface of the target 6a becomes a smooth mirror surface.
  • the phenomenon that the surface of the target 6a is mirrored can also be confirmed by visual observation.
  • the target on which the surface without slag is obtained by this swinging and rotating operation can be deposited by the PLD method after stopping the swinging or rotating.
  • a group III metal is used as a target
  • a material containing Ge, Mg, and Si as impurities in advance can be used.
  • the melting point of these alloys (mixtures) may increase, and needless to say, the heating temperature needs to be changed depending on the impurity species and amount to be added.
  • the material of at least the inner wall surface of the target container 5a is a material that does not react with the target 6a and has poor wettability with the target 6a.
  • alumina, silica, P-BN (Pyrolytic Boron-Nitride: nitriding) By adopting ceramic such as boron) or DLC (Diamond Like Carbon), the movement of the slag 17 toward the inner wall surface side can be promoted.
  • the target container 5a does not need to be made of the above material.
  • the ceramic material may be coated on the inner wall of the target container 5a, for example, by ion plating.
  • FIG. 6C is a cross-sectional view of the target container 5a.
  • the inner wall of the target container 5a may be provided with a taper, or the inner wall may have a vertical shape.
  • a function of swinging (or rotating) the target container 6a may be added to the target support device 3 that supports the target. By swinging, the movement of the slag to the inner wall surface of the target container 5a can be promoted.
  • a motor is installed outside the chamber 1, and the swinging motion may be transmitted directly to the target support device 3 via the shaft, or indirectly via magnetic coupling, or the motor may be transmitted to the chamber 1. It may be installed inside. It may be a swinging motion within a predetermined angle range or a rotational motion.

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Abstract

La présente invention aborde le problème de la réalisation d'un procédé de formation d'un film de nitrure ou d'oxyde sur une surface d'un semiconducteur au nitrure du groupe III tel que le GaN ou similaire, tout en réduisant les défauts sur la surface du semiconducteur au nitrure du groupe III ; et un appareil associé. La solution selon l'invention porte sur un film de nitrure ou d'oxyde qui est formé par évaporation d'un matériau cible par le biais d'un procédé PLD et par réaction du matériau cible avec des radicaux d'azote ou des radicaux d'oxygène, les défauts dus aux lacunes d'azote étant supprimés par chauffage d'un semiconducteur au nitrure du groupe III tout en irradiant des radicaux d'azote sur le semiconducteur de nitrure du groupe III. De plus, l'uniformité de l'épaisseur du film à former peut être améliorée en divisant un faisceau laser en une pluralité de faisceaux.
PCT/JP2018/013082 2017-03-30 2018-03-29 Procédé de formation de films de nitrure et d'oxyde, et appareil associé WO2018181642A1 (fr)

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Citations (6)

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JP2002241930A (ja) * 2001-02-19 2002-08-28 Hamamatsu Photonics Kk 窒化物薄膜作製方法
JP2006059956A (ja) * 2004-08-19 2006-03-02 Matsushita Electric Ind Co Ltd 半導体装置の製造方法
JP2006237556A (ja) * 2005-01-31 2006-09-07 Kanagawa Acad Of Sci & Technol ＧａＮ膜生成方法及び半導体素子並びにＩＩＩ族窒化物の薄膜生成方法及びＩＩＩ族窒化物の薄膜を有する半導体素子
WO2011039853A1 (fr) * 2009-09-30 2011-04-07 キヤノン株式会社 Transistor à couches minces
JP2014173117A (ja) * 2013-03-07 2014-09-22 Jx Nippon Mining & Metals Corp インジウム製円筒形ターゲット部材及び円筒形ターゲット部材の製造方法
JP2016062956A (ja) * 2014-09-16 2016-04-25 アイシン精機株式会社 基板及びその製造方法、半導体素子及びその製造方法、並びにレーザ加工装置

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011181762A (ja) * 2010-03-02 2011-09-15 Tohoku Univ 半導体装置の製造方法

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002241930A (ja) * 2001-02-19 2002-08-28 Hamamatsu Photonics Kk 窒化物薄膜作製方法
JP2006059956A (ja) * 2004-08-19 2006-03-02 Matsushita Electric Ind Co Ltd 半導体装置の製造方法
JP2006237556A (ja) * 2005-01-31 2006-09-07 Kanagawa Acad Of Sci & Technol ＧａＮ膜生成方法及び半導体素子並びにＩＩＩ族窒化物の薄膜生成方法及びＩＩＩ族窒化物の薄膜を有する半導体素子
WO2011039853A1 (fr) * 2009-09-30 2011-04-07 キヤノン株式会社 Transistor à couches minces
JP2014173117A (ja) * 2013-03-07 2014-09-22 Jx Nippon Mining & Metals Corp インジウム製円筒形ターゲット部材及び円筒形ターゲット部材の製造方法
JP2016062956A (ja) * 2014-09-16 2016-04-25 アイシン精機株式会社 基板及びその製造方法、半導体素子及びその製造方法、並びにレーザ加工装置

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