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WO2010113928A1 - Procédé de formation d'un film de nitrure de silicium, procédé de fabrication d'un dispositif de mémoire à semi-conducteur et appareil de dépôt en phase vapeur assisté par plasma - Google Patents

Procédé de formation d'un film de nitrure de silicium, procédé de fabrication d'un dispositif de mémoire à semi-conducteur et appareil de dépôt en phase vapeur assisté par plasma Download PDF

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Publication number
WO2010113928A1
WO2010113928A1 PCT/JP2010/055654 JP2010055654W WO2010113928A1 WO 2010113928 A1 WO2010113928 A1 WO 2010113928A1 JP 2010055654 W JP2010055654 W JP 2010055654W WO 2010113928 A1 WO2010113928 A1 WO 2010113928A1
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Prior art keywords
silicon nitride
nitride film
gas
film
plasma cvd
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Ceased
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PCT/JP2010/055654
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English (en)
Japanese (ja)
Inventor
辰夫 西田
稔 本多
準弥 宮原
敏雄 中西
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Tokyo Electron Ltd
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Tokyo Electron Ltd
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D30/00—Field-effect transistors [FET]
    • H10D30/60—Insulated-gate field-effect transistors [IGFET]
    • H10D30/69—IGFETs having charge trapping gate insulators, e.g. MNOS transistors
    • 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
    • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
    • C23C16/34—Nitrides
    • C23C16/345—Silicon nitride
    • 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
    • C23C16/455—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
    • C23C16/45563—Gas nozzles
    • C23C16/45565—Shower nozzles
    • 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
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D64/00—Electrodes of devices having potential barriers
    • H10D64/01—Manufacture or treatment
    • H10D64/031—Manufacture or treatment of data-storage electrodes
    • H10D64/037—Manufacture or treatment of data-storage electrodes comprising charge-trapping insulators
    • H10P14/6336—
    • H10P14/69433—

Definitions

  • the present invention relates to a method for forming a silicon nitride film, a method for manufacturing a semiconductor memory device, and a plasma CVD apparatus used in these methods.
  • Nonvolatile semiconductor memory device represented by an EEPROM (Electrically Erasable and Programmable ROM) capable of electrical rewriting
  • a SONOS (Silicon-Oxide-Nitride-Oxide-Silicon) type or a MONOS (Metal-Oxide-Metal) is used as a nonvolatile semiconductor memory device represented by an EEPROM (Electrically Erasable and Programmable ROM) capable of electrical rewriting.
  • a SONOS Silicon-Oxide-Nitride-Oxide-Silicon
  • MONOS Metal-Oxide-Metal
  • Some have a laminated structure called a nitride-oxide-silicon type.
  • information is held by using one or more silicon nitride films (Nitride) sandwiched between silicon dioxide films (Oxide) as a charge storage region.
  • the nonvolatile semiconductor memory device by applying a voltage between the semiconductor substrate (Silicon) and the control gate electrode (Silicon or Metal), electrons are injected into the silicon nitride film in the charge storage region, and data is thus obtained. Data is stored and erased and rewritten by removing electrons accumulated in the silicon nitride film.
  • the data write characteristic is related to the ease of injection of electrons into the silicon nitride film, which is a charge storage region, and is particularly related to the charge trapping center (trap) present in the silicon nitride film. It is believed that there is.
  • Japanese Patent Application Laid-Open No. 5-145078 discloses that an intermediate portion of these films contains a large amount of Si for the purpose of increasing the trap density at the interface between the silicon nitride film and the top oxide film. The provision of a transition layer is described.
  • nonvolatile semiconductor memory devices With the recent high integration of semiconductor devices, the element structure of nonvolatile semiconductor memory devices is rapidly miniaturized. In order to miniaturize the nonvolatile semiconductor memory device, it is necessary to increase the number of traps in the silicon nitride film, which is a charge storage layer, in each nonvolatile semiconductor memory device to improve the data writing performance.
  • the low pressure CVD Chemical Vapor Deposition
  • the thermal CVD method it is possible to form many traps in the silicon nitride film by setting the processing pressure in the processing container to a high vacuum state (for example, 3 Pa or less) and strengthening the ionicity of the plasma.
  • a vacuum seal technology that can withstand the high vacuum state, a pressure vessel, a high-performance exhaust device, etc. For example, the load on the apparatus increases and the cost increases.
  • the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a nitridation useful as a charge storage layer of a nonvolatile semiconductor memory device, in which many traps exist and the distribution in the film thickness direction of the traps is controlled. It is to provide a method for forming a silicon film by a plasma CVD method.
  • the silicon nitride film forming method of the present invention is a silicon nitride film forming method in which a silicon nitride film is deposited on an object to be processed by a plasma CVD method in a processing vessel of a plasma CVD apparatus, Supplying a processing gas containing a silicon-containing compound gas and a nitrogen-containing gas into the processing container to generate plasma, and forming a silicon nitride film on the object to be processed; Oxygen atom-containing gas introduction step of stopping the plasma in the middle of the silicon nitride film forming step, introducing an oxygen atom-containing gas into the processing vessel, and exposing the silicon nitride film being formed to oxygen to form a trap And.
  • the silicon nitride film forming step includes a first step of growing a silicon nitride film by the plasma before the oxygen atom-containing gas introduction step, and the oxygen atom-containing step. It is preferable that a second step of growing a silicon nitride film by the plasma is provided after the gas introduction step. In this case, it is preferable that the oxygen atom-containing gas introduction step is performed at a stage where the silicon nitride film has grown to a thickness in the range of 30% to 70% with respect to the target film thickness.
  • the plasma CVD apparatus may be a plasma CVD apparatus that generates plasma by introducing microwaves into the processing vessel using a planar antenna having a plurality of holes. preferable.
  • a method for manufacturing a semiconductor memory device of the present invention is a method for manufacturing a semiconductor memory device in which a tunnel oxide film, a silicon nitride film as a charge storage layer, a block silicon oxide film, and a gate electrode are formed on a silicon layer.
  • Formation of a silicon nitride film as the charge storage layer Supplying a processing gas containing a silicon-containing compound gas and a nitrogen-containing gas into a processing vessel of a plasma CVD apparatus to generate plasma, and forming a silicon nitride film on the object to be processed by a plasma CVD method; Oxygen atom-containing gas introduction step of stopping the plasma in the middle of the silicon nitride film forming step, introducing an oxygen atom-containing gas into the processing vessel, and exposing the silicon nitride film being formed to oxygen to form a trap When, Is performed by a method of forming a silicon nitride film including
  • the plasma CVD apparatus of the present invention is A processing container for mounting and storing the object to be processed on the mounting table; A gas supply device for supplying a processing gas into the processing container; An exhaust device for evacuating the inside of the processing vessel;
  • a processing gas containing a silicon-containing compound gas and a nitrogen-containing gas is supplied into the processing container to generate plasma,
  • the plasma is stopped, an oxygen atom-containing gas is introduced into the processing container, and the silicon nitride film being formed is oxygenated.
  • An oxygen atom-containing gas introduction step for forming a trap by exposure to a control unit, and a control unit that controls so as to perform a method of forming a silicon nitride film, It has.
  • the plasma is temporarily stopped, the oxygen atom-containing gas is introduced into the processing container, and the film is formed.
  • the trap distribution in the film thickness direction of the silicon nitride film can be easily controlled by timing the introduction of oxygen.
  • a silicon nitride film in which many traps are present in a predetermined distribution can be manufactured by a simple method by controlling a gas system.
  • the silicon nitride film formed by the method of the present invention has many traps in the film and the distribution of traps in the film thickness direction is controlled to an optimum position, the film is formed into a non-volatile semiconductor. By using it as a charge storage layer of a memory device, a nonvolatile semiconductor memory device having excellent writing characteristics can be obtained.
  • the position of the introduction of O 2 in the thickness direction of the silicon nitride film is an explanatory view showing a.
  • 6 is a graph showing the measurement result of ⁇ Vfb in Test Example 1.
  • It is an energy band figure which shows distribution of the trap in the silicon nitride film formed by performing plasma CVD on normal conditions.
  • 6 is a graph showing a measurement result of ⁇ Vfb in Test Example 2. It is a schematic sectional drawing which shows the structural example of the semiconductor memory device which can apply the method of this invention.
  • FIG. 1 is a cross-sectional view schematically showing a schematic configuration of a plasma CVD apparatus 100 that can be used in the silicon nitride film forming method of the present invention.
  • the plasma CVD apparatus 100 generates a plasma by introducing a microwave into a processing container using a planar antenna having a plurality of slot-shaped holes, particularly an RLSA (Radial Line Slot Antenna). It is configured as an RLSA microwave plasma processing apparatus that can generate microwave-excited plasma having a density and a low electron temperature.
  • RLSA Random Line Slot Antenna
  • the plasma CVD apparatus 100 treatment with plasma having a plasma density of 1 ⁇ 10 10 to 5 ⁇ 10 12 / cm 3 and a low electron temperature of 0.7 to 2 eV is possible. Therefore, the plasma CVD apparatus 100 can be suitably used for the purpose of forming a silicon nitride film by plasma CVD in the manufacturing process of various semiconductor devices.
  • the plasma CVD apparatus 100 includes, as main components, an airtight processing container 1, a gas supply device 18 for supplying a processing gas into the processing container 1, and an exhaust mechanism for exhausting the processing container 1 under reduced pressure.
  • the processing container 1 is formed of a grounded substantially cylindrical container. Note that the processing container 1 may be formed of a rectangular tube-shaped container.
  • the processing container 1 has a bottom wall 1a and a side wall 1b made of a material such as aluminum.
  • a processing table 1 is provided with a mounting table 2 for horizontally supporting a silicon wafer (hereinafter simply referred to as a “wafer”) W as an object to be processed.
  • the mounting table 2 is made of a material having high thermal conductivity, such as ceramics such as AlN.
  • the mounting table 2 is supported by a cylindrical support member 3 extending upward from the center of the bottom of the exhaust chamber 11.
  • the support member 3 is made of ceramics such as AlN, for example.
  • the mounting table 2 is provided with a cover ring 4 that covers the outer edge portion thereof and guides the wafer W.
  • the cover ring 4 is an annular member made of a material such as quartz, AlN, Al 2 O 3 , or SiN.
  • a resistance heating type heater 5 as a temperature adjusting mechanism is embedded in the mounting table 2.
  • the heater 5 is heated by the heater power supply 5a to heat the mounting table 2 and uniformly heats the wafer W, which is a substrate to be processed, with the heat.
  • thermocouple (TC) 6 is inserted in the mounting table 2.
  • the heating temperature of the wafer W can be controlled in a range from room temperature to 900 ° C., for example.
  • the mounting table 2 has wafer support pins (not shown) for supporting the wafer W and moving it up and down.
  • Each wafer support pin is provided so as to protrude and retract with respect to the surface of the mounting table 2.
  • a circular opening 10 is formed at a substantially central portion of the bottom wall 1a of the processing container 1.
  • An exhaust chamber 11 that communicates with the opening 10 and projects downward is provided on the bottom wall 1a.
  • An exhaust pipe 12 is connected to the exhaust chamber 11 and is connected to an exhaust device 24 via the exhaust pipe 12.
  • a plate 13 having a function as a lid (lid) for opening and closing the processing container 1 is disposed on the upper part of the processing container 1.
  • the plate 13 has an opening, and the inner peripheral portion of the plate 13 protrudes toward the inside (the processing container internal space) to form an annular support portion 13a.
  • the gas introduction part is provided in the upper part of the processing container 1.
  • FIG. The gas introduction part is formed in the plate 13 and is formed under the gas introduction hole 14 as a “first gas introduction hole” for introducing at least one kind of gas, and at least one kind of gas.
  • a gas introduction hole 15 is provided as a “second gas introduction hole”. That is, the gas introduction holes 14 and 15 are provided in the upper and lower stages in the gas introduction part.
  • Each gas introduction hole is connected to a gas supply device 18 for supplying a processing gas via a gas introduction pipe.
  • the gas introduction holes 14 and 15 may be provided in a nozzle shape or a shower head shape. Further, the gas introduction hole 14 and the gas introduction hole 15 may be provided in a single shower head.
  • a loading / unloading port 16 for loading / unloading the wafer W between the plasma CVD apparatus 100 and a transfer chamber (not shown) adjacent to the plasma CVD apparatus 100 is provided on the side wall 1b of the processing container 1.
  • a gate valve 17 for opening and closing 16 is provided.
  • the gas supply device 18 includes a gas supply source (for example, a nitrogen (N) -containing gas supply source 19a, an oxygen atom-containing gas supply source 19b, a silicon (Si) -containing gas supply source 19c, an inert gas supply source 19d, and a cleaning gas supply.
  • a gas supply source for example, a nitrogen (N) -containing gas supply source 19a, an oxygen atom-containing gas supply source 19b, a silicon (Si) -containing gas supply source 19c, an inert gas supply source 19d, and a cleaning gas supply.
  • Source 19e gas introduction pipes (eg, gas introduction pipes 20a, 20b, 20c, 20d, 20e), flow control devices (eg, mass flow controllers 21a, 21b, 21c, 21d, 21e), and valves (eg, Open / close valves 22a, 22b, 22c, 22d, 22e).
  • the nitrogen-containing gas supply source 19a and the oxygen atom-containing gas supply source 19b are connected to the upper gas introduction hole 14 through gas introduction pipes 20a and 20b. Further, the Si-containing gas supply source 19c, the inert gas supply source 19d, and the cleaning gas supply source 19e are connected to the lower gas introduction hole 15 through gas introduction pipes 20c, 20d, and 20e.
  • the cleaning gas supply source 19e is used when an unnecessary film attached in the processing container 1 is cleaned.
  • the gas supply apparatus 18 may have a purge gas supply source used when replacing the atmosphere in the processing container 1, for example, as a gas supply source (not shown) other than the above.
  • oxygen O 2
  • ozone O 3
  • nitrogen monoxide NO
  • nitrogen dioxide NO 2
  • dinitrogen monoxide N 2 O
  • Examples of the silicon (Si) -containing gas include silane (SiH 4 ), disilane (Si 2 H 6 ), tetrachlorosilane (SiCl 4 ), hexachlorodisilane (Si 2 Cl 6 ), dichlorosilane (SiH 2 Cl 2 ), Trichlorosilane (Si 2 HCl 3 ), trisilane (Si 3 H 8 ), trisilylamine ((SiH 3 ) 3 N) and the like can be used, and among them, a compound gas composed of silicon atoms and chlorine atoms, for example, Tetrachlorosilane (SiCl 4 ) or hexachlorodisilane (Si 2 Cl 6 ) is preferably used.
  • nitrogen gas (N 2 ) nitrogen gas (N 2 ), ammonia (NH 3 ), hydrazine (N 2 H 4 ), monomethyl hydrazine (CH 6 N 2 ), etc. can be used. It is preferable to use N 2 gas which does not contain.
  • N 2 gas which does not contain.
  • the combination of tetrachlorosilane (SiCl 4 ) or hexachlorodisilane (Si 2 Cl 6 ) composed of silicon atoms and chlorine atoms and N 2 is a combination that can be preferably used in the present invention because it does not contain hydrogen in the source gas molecules. .
  • a rare gas as the inert gas
  • Ar gas, Kr gas, Xe gas, He gas, or the like can be used.
  • the purge gas is preferably an inert gas such as Ar gas or nitrogen gas.
  • the N-containing gas and the oxygen atom-containing gas reach the gas introduction hole 14 from the nitrogen-containing gas supply source 19a and the oxygen atom-containing gas supply source 19b of the gas supply device 18 through the gas introduction pipes 20a and 20b, respectively. It is introduced into the processing container 1 from the hole 14.
  • the Si-containing gas, the inert gas, and the cleaning gas are supplied from the Si-containing gas supply source 19c, the inert gas supply source 19d, and the cleaning gas supply source 19e through the gas introduction pipes 20c, 20d, and 20e, respectively. 15, and introduced into the processing container 1.
  • the gas introduction pipes 20a to 20e connected to the respective gas supply sources are provided with mass flow controllers 21a to 21e and front and rear opening / closing valves 22a to 22e.
  • the supplied gas can be switched and the flow rate can be controlled.
  • the rare gas for plasma excitation such as Ar gas is an arbitrary gas and does not necessarily need to be supplied at the same time as the processing gas (Si-containing gas, N-containing gas), but is added from the viewpoint of stabilizing the plasma. Is more preferable.
  • Ar gas it is more preferable to use Ar gas as a carrier gas for supplying the Si-containing gas into the processing container at a stable flow rate.
  • the exhaust device 24 includes a vacuum pump (not shown) such as a turbo molecular pump.
  • the vacuum pump is connected to the exhaust chamber 11 of the processing container 1 via an exhaust pipe 12.
  • the gas in the processing container 1 uniformly flows into the space 11a of the exhaust chamber 11, and is further exhausted to the outside through the exhaust pipe 12 from the space 11a.
  • the inside of the processing container 1 can be uniformly decompressed at a high speed, for example, to 0.133 Pa.
  • the microwave introduction mechanism 27 includes a transmission plate 28, a planar antenna 31, a slow wave material 33, a metal cover member 34, a waveguide 37, and a microwave generator 39 as main components.
  • the transmission plate 28 that transmits microwaves is provided on a support portion 13 a that protrudes toward the inner periphery of the plate 13.
  • the transmission plate 28 can be made of a dielectric material such as quartz or ceramics (Al 2 O 3 , AlN, etc.).
  • a gap between the transmission plate 28 and the support portion 13a is hermetically sealed through a seal member 29. Therefore, the inside of the processing container 1 is kept airtight.
  • the planar antenna 31 is provided above the transmission plate 28 so as to face the mounting table 2.
  • the planar antenna 31 has a disk shape.
  • the shape of the planar antenna 31 is not limited to a disk shape, and may be a square plate shape, for example.
  • the planar antenna 31 is disposed on the plate 13.
  • the planar antenna 31 is made of, for example, a copper plate, a nickel plate, a SUS plate or an aluminum plate whose surface is plated with gold or silver.
  • the planar antenna 31 has a number of slot-shaped microwave radiation holes 32 that radiate microwaves.
  • the microwave radiation holes 32 are formed through the planar antenna 31 in a predetermined pattern.
  • the microwave radiation hole 32 has an elongated rectangular shape (slot shape), for example, as shown in FIG. 2, and two adjacent microwave radiation holes form a pair.
  • a pair of adjacent microwave radiation holes 32 are typically arranged in a predetermined pattern in a “T” shape or a “V” shape.
  • the microwave radiation holes 32 arranged in combination in this way are arranged concentrically, and the microwaves are introduced into the processing container 1 by concentric polarization, and uniform plasma is formed.
  • the length and arrangement interval of the microwave radiation holes 32 are determined according to the wavelength ( ⁇ g) of the microwave.
  • the interval between the microwave radiation holes 32 is arranged to be ⁇ g / 4 to ⁇ g.
  • the interval between adjacent microwave radiation holes 32 formed concentrically is indicated by ⁇ r.
  • the microwave radiation hole 32 may have another shape such as a circular shape or an arc shape.
  • the arrangement form of the microwave radiation holes 32 is not particularly limited, and may be arranged in a spiral shape, a radial shape, or the like in addition to a concentric shape.
  • a slow wave material 33 having a dielectric constant larger than that of a vacuum is provided on the upper surface of the planar antenna 31.
  • the slow wave material 33 has a function of adjusting the plasma by shortening the wavelength of the microwave because the wavelength of the microwave becomes longer in vacuum.
  • planar antenna 31 and the transmission plate 28 and the slow wave member 33 and the planar antenna 31 may be brought into contact with or separated from each other, but are preferably brought into contact with each other.
  • a metal cover member 34 is provided on the upper portion of the processing container 1 so as to cover the planar antenna 31 and the slow wave material 33.
  • the metal cover member 34 is formed of a metal material such as aluminum or stainless steel, and constitutes a flat waveguide together with the planar antenna 31.
  • the upper end of the plate 13 and the metal cover member 34 are sealed by a seal member 35.
  • a cooling water channel 34 a is formed inside the metal cover member 34.
  • An opening 36 is formed in the center of the upper wall (ceiling part) of the metal cover member 34, and a waveguide 37 is connected to the opening 36.
  • the other end of the waveguide 37 is connected to a microwave generator 39 that generates a microwave via a matching circuit 38.
  • the waveguide 37 extends in the horizontal direction connected to the coaxial waveguide 37a having a circular cross section extending upward from the opening 36 of the metal cover member 34 and the upper end of the coaxial waveguide 37a. And a rectangular waveguide 37b.
  • An inner conductor 41 extends in the center of the coaxial waveguide 37a.
  • the inner conductor 41 is made of metal copper or the like, and is connected and fixed to the center of the planar antenna 31 at the lower end thereof. With such a structure, the microwave propagates through the inner conductor 41 of the coaxial waveguide 37a and is introduced into the planar antenna 31, and is efficiently propagated radially and uniformly to the flat waveguide.
  • the microwave generated by the microwave generator 39 is propagated to the planar antenna 31 via the waveguide 37 and further into the processing container 1 via the transmission plate 28. It has been introduced.
  • the microwave frequency for example, 2.45 GHz is preferably used, and 8.35 GHz, 1.98 GHz, or the like can be used.
  • the control unit 50 includes a computer, and includes, for example, a process controller 51 including a CPU, a user interface 52 connected to the process controller 51, and a storage unit 53 as illustrated in FIG.
  • the process controller 51 is a component related to process conditions such as temperature, pressure, gas flow rate, and microwave output (for example, heater power supply 5a, gas supply device 18, exhaust device 24, microwave). This is a control means for controlling the generator 39 and the like in an integrated manner.
  • the user interface 52 includes a keyboard on which a process administrator manages command input to manage the plasma CVD apparatus 100, a display that visualizes and displays the operating status of the plasma CVD apparatus 100, and the like.
  • the storage unit 53 stores a recipe in which a control program (software) for realizing various processes executed by the plasma CVD apparatus 100 under the control of the process controller 51 and processing condition data are recorded. Yes.
  • recipes such as the control program and processing condition data may be stored in a computer-readable storage medium such as a CD-ROM, hard disk, flexible disk, flash memory, DVD, or Blu-ray disk. Alternatively, it may be transmitted from other devices as needed via, for example, a dedicated line and used online.
  • FIG. 4 is a timing chart of introduction of microwaves, SiCl 4 gas, N 2 gas, and O 2 gas in the film forming process of the silicon nitride film.
  • N 2 gas is supplied from the nitrogen-containing gas supply source 19 a of the gas supply device 18 through the gas introduction hole 14, and the Si-containing gas supply source 19 c and the inert gas supply are supplied.
  • SiCl 4 gas and, if necessary, Ar gas are introduced into the processing container 1 through the gas introduction hole 15 at a predetermined flow rate (t 0 in FIG. 4).
  • the inside of the processing container 1 is set to a predetermined pressure. The conditions at this time will be described later.
  • a microwave having a predetermined frequency, for example, 2.45 GHz, generated by the microwave generator 39 is guided to the waveguide 37 through the matching circuit 38 (t 1 in FIG. 4).
  • the microwave guided to the waveguide 37 sequentially passes through the rectangular waveguide 37b and the coaxial waveguide 37a and is supplied to the planar antenna 31 constituting the flat waveguide through the inner conductor 41.
  • the microwaves propagate radially from the coaxial waveguide 37 a toward the planar antenna 31.
  • the microwaves are radiated as circularly polarized waves from the slot-shaped microwave radiation holes 32 of the planar antenna 31 to the space above the wafer W in the processing chamber 1 through the transmission plate 28.
  • An electromagnetic field is formed in the processing container 1 by the microwave transmitted through the transmission plate 28 from the planar antenna 31 and radiated into the processing container 1, and N 2 gas, SiCl 4 gas, and Ar gas are turned into plasma, respectively. Then, dissociation of the source gas efficiently proceeds in the plasma, and silicon nitride (SiN; where the composition ratio of Si and N is not always determined stoichiometrically by reaction of active species (ions, radicals, etc.). In this case, a thin film having a different value depending on the film forming conditions is applied. This plasma CVD process is performed in a section from t 1 to t 4 in FIG.
  • the plasma is stopped for a predetermined time (interval between t 2 and t 3 in FIG. 4) during the formation of the silicon nitride film by the plasma CVD process, and oxygen atoms
  • Oxygen atom-containing gas introduction step in this case, typically O 2 gas is used
  • an oxygen atom-containing gas such as O 2 gas into the processing container 1 from the contained gas supply source 19b through the gas introduction hole 14.
  • O 2 gas flow oxygen atom-containing gas
  • the purpose of this O 2 gas flow is to form a trap by exposing the silicon nitride film being formed to oxygen to generate Si—O bonds.
  • the silicon nitride film forming step causes the silicon nitride film to grow by plasma before the O 2 gas flow by interposing the O 2 gas flow.
  • the first step (from t 1 in FIG. 4 t 2 sections) and, O 2 after the gas flow, the second step (interval t 4 from t 3 in FIG. 4) growing a silicon nitride film by plasma And is divided into That is, a first silicon nitride film is formed by plasma, a trap is formed by exposing the first silicon nitride film to an oxygen atom-containing gas, and a second silicon nitride film is formed thereon by plasma. Further, in the oxygen atom-containing gas introduction step, Si—O bonds may be formed so as to be uniformly scattered in a plane, and traps may be uniformly scattered.
  • FIG. 5A to 5D are cross-sectional views of the vicinity of the surface of the wafer W showing the steps of forming a silicon nitride film performed in the plasma CVD apparatus 100.
  • FIG. 5A for example, an SiCl 4 / N 2 gas plasma is generated on an arbitrary underlayer (here, SiO 2 film 60) using a plasma CVD apparatus 100, and silicon nitride is formed by plasma CVD.
  • a film (SiN film) 70a is formed (first step).
  • the formation of the SiN film 70a in the first step can be performed under the following conditions by supplying a processing gas containing SiCl 4 gas as the Si-containing gas and N 2 gas as the nitrogen-containing gas into the processing chamber 1. In this case, a rare gas may be added to generate stable plasma and supply gas stably.
  • the treatment pressure is preferably in the range of 0.1 Pa to 6.7 Pa, and more preferably in the range of 0.1 Pa to 4 Pa.
  • the lower the processing pressure the better.
  • the processing pressure exceeds 6.7 Pa, the dissociation of SiCl 4 gas is small, the reaction with nitrogen does not proceed, and sufficient film formation cannot be performed, which is not preferable.
  • the flow rate of the SiCl 4 gas is preferably set to 0.5 mL / min (sccm) or more and 10 mL / min (sccm) or less, and is set to 0.5 mL / min (sccm) or more and 2 mL / min (sccm) or less. More preferably. The same applies when other types of Si-containing gas are used.
  • the ratio of N 2 gas flow rate (N 2 gas / percentage of total process gas flow rate) to the total process gas flow rate is preferably 5% or more and 99% or less, and 40% or more and 99% or less. Is more preferable.
  • the flow rate of N 2 gas is preferably set to 100 mL / min (sccm) or more and 5000 mL / min (sccm) or less, and more preferably set to 100 mL / min (sccm) or more and 2000 mL / min (sccm) or less. preferable. The same applies when other types of N-containing gas are used.
  • the flow rate ratio of Ar gas is preferably 10% or more and 90% or less, and preferably 10% or more and 60% or less with respect to the total process gas flow rate. More preferred.
  • the flow rate of rare gas such as Ar is preferably set to 10 mL / min (sccm) or more and 1000 mL / min (sccm) or less, and preferably set to 10 mL / min (sccm) or more and 500 mL / min (sccm) or less. Is more preferable.
  • the temperature of the plasma CVD process may be set so that the temperature of the mounting table 2 is 300 ° C. or higher, preferably 400 ° C. or higher and 600 ° C. or lower.
  • the microwave output in the plasma CVD apparatus 100 is preferably in the range of 0.25 to 2.56 W / cm 2 as the power density per area of the transmission plate 28.
  • the microwave output can be selected from the range of 500 to 5000 W, for example, so that the power density is within the above range according to the purpose.
  • the plasma is stopped and O 2 gas is supplied from the oxygen atom-containing gas supply source 19b for a short time (oxygen atom-containing gas introduction step). That is, the supply of microwaves, SiCl 4 and N 2 into the processing vessel 1 is temporarily stopped (between t 2 and t 3 in FIG. 4) to extinguish the plasma, and O 2 is put into the processing vessel 1.
  • a gas is introduced into the processing container 1, and the surface of the SiN film 70a formed by the plasma CVD process in the first step is exposed to oxygen. Thereby, a very small amount of oxygen can be introduced into the surface of the SiN film 70a.
  • oxygen atom-containing gas for example, O 3 gas, NO gas, NO 2 gas, N 2 O gas, or the like can be used instead of O 2 gas.
  • O 2 gas flow O 2 within a range that does not impair the effect of the gas flow can be introduced together with the O 2 gas as a rare gas or nitrogen gas or the like as a carrier gas.
  • the supply of N 2 gas is stopped in FIG. 4, the supply of N 2 gas may not be stopped.
  • O 2 gas flow O 2 in the range of 30 to 70% of the timing example target film thickness approaching the vicinity of the center of (the total thickness of the SiN film 70) target film thickness growth of the SiN film 70a is in the film thickness direction
  • a gas flow is preferably performed, and an O 2 gas flow is more preferably performed within a range of 40 to 60%. In this way, as will be described later, excellent data writing characteristics can be obtained when used as a charge storage layer in a nonvolatile semiconductor memory device.
  • the time for one O 2 gas flow is preferably in the range of 10 seconds to 300 seconds, for example, and more preferably in the range of 30 seconds to 120 seconds.
  • the flow rate of O 2 O 2 gas used in the gas flow for example, 10 mL / min (sccm) or 2000 mL / min (sccm) or less preferably, 100 mL / min (sccm) or 2000 mL / min (sccm ) Is more preferably set to 100 mL / min (sccm) or more and 1000 mL / min (sccm) or less.
  • oxygen-containing gas for example, 10 mL / min (sccm) or 2000 mL / min (sccm) or less preferably, 100 mL / min (sccm) or 2000 mL / min (sccm ) Is more preferably set to 100 mL / min (sccm) or more and 1000 mL / min (sccm) or less.
  • oxygen-containing gas for example, 10 mL / min (sccm) or 2000 mL / min
  • the pressure in the processing container 1 during the O 2 gas flow is determined by the first step (interval between t 1 and t 2 in FIG. 4) and the second step (t 3 in FIG. 4) of plasma CVD performed before and after that. equal or higher pressure and t 4 sections) from, for example, preferably set to 0.1 ⁇ 133.3 Pa. Note that by setting the pressure during the O 2 gas flow higher than the pressure during the formation of the silicon nitride film, the residence time of the O 2 gas in the processing vessel 1 is lengthened, and the effect of the O 2 gas flow is further enhanced. be able to.
  • the plasma CVD process is resumed under the same conditions as in the first step (second step). That is, as shown in FIG. 5C and FIG. 5D, the supply of microwaves, SiCl 4 and N 2 is resumed into the processing container 1 again to generate SiCl 4 / N 2 gas plasma.
  • a second SiN film 70b is deposited and laminated on the formed first SiN film 70a.
  • the SiN film 70 can be formed with a target film thickness, for example, in the range of 2 nm to 300 nm, preferably in the range of 2 nm to 50 nm.
  • the power of the microwave generator 39 is turned off to stop the plasma (t 4 in FIG. 4 ).
  • the supply of SiCl 4 and N 2 is stopped (t 5 in FIG. 4).
  • the wafer W is unloaded from the plasma CVD apparatus 100 in the reverse procedure.
  • FIG. 5D the position where the O 2 gas is introduced in the SiN film 70 formed to the target film thickness is indicated by a broken line. Since the introduction of the O 2 gas is performed while the plasma is stopped, the amount of oxygen mixed into the SiN film 70 is very small. The TEM (transmission electron microscope) or XPS (X-ray photoelectron spectroscopy) analysis of the SiN film 70 is performed. Etc., a clear layer structure is not observed. However, due to the O 2 gas flow, at the introduction position of the O 2 gas in the SiN film 70 shown in FIG. 5D, at least two-dimensionally, Si—O bonds are formed in a monolayer (Monolayer) or several monolayers and a high trap.
  • a monolayer monolayer
  • monolayer monolayer
  • a density region (trap layer) is formed.
  • the O 2 gas flow is performed at a timing approaching the center of the target film thickness (total film thickness of the SiN film 70), for example, within a range of 30 to 70% (preferably within a range of 40 to 60%) of the target film thickness.
  • the trap layer by the O 2 gas flow can be formed within a thickness within ⁇ 20%, preferably within ⁇ 10% from the center in the film thickness direction of the SiN film 70, and the SiN film 70.
  • the above conditions are stored as recipes in the storage unit 53 of the control unit 50. Then, the process controller 51 reads the recipe and sends a control signal to each component of the plasma CVD apparatus 100 such as the heater power supply 5a, the gas supply apparatus 18, the exhaust apparatus 24, the microwave generation apparatus 39, etc. Plasma CVD processing under conditions is realized.
  • the SiN film 70 obtained as described above has many traps, for example, when used as a charge storage layer of a semiconductor memory device, data write characteristics are improved. Further, for example, by applying a silicon nitride film formed by the method of the present invention as a charge storage region of a semiconductor memory device, a semiconductor memory device having excellent data writing characteristics can be manufactured.
  • FIG. 6 is a timing chart of introduction of microwaves, SiCl 4 gas, N 2 gas, and O 2 gas in the film forming process of the silicon nitride film in the present embodiment.
  • FIG. 7 shows the position of introducing O 2 gas in the silicon nitride film formed in this embodiment.
  • SiCl 4 gas and N 2 gas are used as the processing gas, but the same applies to the case where other Si-containing gas or N-containing gas is used.
  • the O 2 gas flow is performed only once (interval from t 2 to t 3 in FIG. 4) during the plasma CVD process, but in this embodiment, the O 2 gas flow is changed.
  • This is different from the first embodiment in that it is repeated twice or more.
  • This embodiment is the same as the first embodiment except that the O 2 gas flow is repeated two or more times. Therefore, the following description will focus on the differences. Also in FIGS. 6 and 7, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
  • the plasma CVD process in the present embodiment is performed in the section from t 11 to t 16 in FIG. 6 to form the SiN film 70.
  • a predetermined time only (interval t 15 from t 12 in FIG. 6 from the interval and t 14 of t 13), to implement the O 2 gas flow stops plasma. That is, the first step after (from t 11 in FIG. 6 t 12 interval) of microwave, SiCl 4 gas and N 2 gas oxygen atom-containing gas supply source 19b to stop the supply to the processing chamber 1
  • the O 2 gas is supplied into the processing container 1 for a short time (first O 2 gas flow; section from t 12 to t 13 in FIG. 6).
  • the microwave, SiCl 4 gas, and N 2 gas are supplied again into the processing container 1, and the SiN film 70 is formed by plasma CVD processing under the same conditions as in the first step. It resumes (second step; interval t 14 from t 13 in FIG. 6).
  • the supply of microwaves, SiCl 4 gas, and N 2 gas into the processing container 1 is stopped again, and O 2 gas is supplied into the processing container 1 from the oxygen atom-containing gas supply source 19b for a short time (second time) O 2 gas flow; t 14 to t 15 in FIG. 6).
  • the lengths of the sections t 12 to t 13 and the sections t 14 to t 15 may be the same or different, and are preferably 10 to 300 seconds, for example, 30 seconds to 120 seconds. Is more preferable.
  • the microwave, SiCl 4 gas, and N 2 gas are supplied again into the processing container 1, and the plasma CVD process is resumed under the same conditions as in the first step (third). steps; interval t 16 from t 15 in FIG. 6).
  • This third step is substantially the same as the second step except for the process time.
  • process purge gas respectively vessel 1 It is preferable that the residual film forming gas be removed by introducing the gas into the gas, thereby enhancing the effect of the O 2 gas flow.
  • FIG. 7 shows the O 2 gas introduction position in the film thickness direction of the SiN film 70 formed by performing the O 2 gas flow twice during the plasma CVD process. Even when the O 2 gas flow is performed twice or more, as in the first embodiment, the timing at which the growth of the SiN film 70 approaches the half of the target film thickness in the film thickness direction, for example, the target film for film formation
  • the O 2 gas flow is preferably performed within a range of 30 to 70% of the thickness, and more preferably O 2 gas flow is performed within a range of 40 to 60%.
  • the target film deposition More preferably, the second O 2 gas flow is performed at a timing before reaching 70% of the thickness.
  • the SiN film 70 having a trap is used as a charge storage layer in a nonvolatile semiconductor memory device, excellent data writing characteristics can be obtained.
  • the O 2 gas flow by performing the O 2 gas flow a plurality of times during the plasma CVD process, traps can be formed in layers in the SiN film 70, and the SiN film 70 having many traps can be formed. .
  • the writing characteristics when the SiN film 70 is used as a charge storage layer of the nonvolatile semiconductor memory device are further improved as compared with the case where the O 2 gas flow is performed only once. be able to.
  • the number of O 2 gas flows is not limited to two, and can be repeated three or more times. When the O 2 gas flow is repeated three or more times, the O 2 gas flow and the second step can be repeated as a set.
  • test device having a SONOS structure as shown in FIG. 8 was prepared.
  • reference numeral 60 is a SiO 2 film
  • reference numeral 70 is a silicon nitride film having a trap
  • reference numeral 80 is a block SiO 2 film
  • reference numeral 90a is a Si substrate made of single crystal silicon
  • reference numeral 90b is a polycrystalline silicon film.
  • the SiN film 70 functions as a charge storage layer
  • the polycrystalline silicon film 90b functions as a control gate electrode.
  • the silicon substrate 90a is grounded and applied to the polycrystalline silicon film 90b by changing the voltage within a predetermined range (forward), and then changing the voltage in the reverse direction (reverse).
  • the capacitance in the process was measured, and ⁇ Vfb (Vfb hysteresis) was determined from the forward and reverse CV curves (hysteresis curves).
  • the fact that the CV curve changes due to the reciprocal voltage application means that, as a result of the holes being trapped in the SiN film 70 by the voltage application, the voltage change occurs to cancel the charge, and Vfb It shows that the larger the hysteresis, the more traps in the SiN film 70 and the better the write characteristics.
  • a voltage in the range of 4 to 6 V was applied to the test device of FIG. 8 to measure ⁇ Vfb, and the data writing characteristics were evaluated.
  • Test example 1 In this test, the SiN film 70 is formed by 1-A) normal plasma CVD, 1-B) plasma CVD film formation + O 2 gas flow (once; center in the film thickness direction), 1-C) plasma CVD film formation + O Films were formed by four film formation methods: two gas flows (twice; near the interface), 1-D) plasma CVD (introduction of O 2 gas in all sections; SiON film formation). The conditions in each film forming method are as follows.
  • Plasma CVD All-section O 2 gas introduction; SiON film formation
  • a plasma CVD apparatus 100 was used.
  • Ar gas flow rate 40 mL / min (sccm)
  • N 2 gas flow rate 450 mL / min (sccm)
  • O 2 gas flow rate 1 mL / min (sccm) SiCl 4 gas flow rate; 1 mL / min (sccm)
  • Processing pressure 2.7 Pa (20 mTorr)
  • Processing temperature mounting table): 500 ° C
  • Microwave power 3kW Processing time: 150 seconds
  • Target film thickness 8 nm
  • FIG. 9 shows the measurement result of ⁇ Vfb indicating the writing characteristics to the silicon nitride film (including the silicon nitride oxide film) formed under the above conditions.
  • the horizontal axis in FIG. 9 is the data writing time, and the scales “1E ⁇ n” and “1E + n” (n is a number) mean “1 ⁇ 10 ⁇ n ” and “1 ⁇ 10 n ”, respectively. (The same applies to FIG. 11).
  • the O 2 gas flow was carried out at about half the target film thickness (near the center in the film thickness direction), a high ⁇ Vfb was shown in comparison with a normal silicon nitride film formed by plasma CVD without any oxygen introduction.
  • FIG. 10A shows a case where a silicon nitride film is formed by performing plasma CVD under normal conditions
  • FIG. 10B shows a case where a silicon nitride film is formed by performing one O 2 gas flow during the plasma CVD process
  • 10C shows the distribution modeling of traps in the silicon nitride film in the case where the O 2 gas flow is performed immediately before and after the formation of the SiN film 70 (two times in total), respectively, as in FIG. This is schematically shown in the energy band diagram of the laminated body having the SONOS structure.
  • FIG. 10B shows a case where the SiN film 70 is formed twice, and the O 2 gas flow is performed once during that time.
  • the meanings of reference numerals in FIGS. 10A to 10C are the same as those in FIG.
  • the traps T are concentrated and distributed in the vicinity of the interface with the adjacent SiO 2 film 60 of the underlying layer.
  • the trap T is located near the center in the film thickness direction of the SiN film 70 (in the film) as shown in FIG. 10B. Concentrated and distributed.
  • the trap T is formed on the underlying SiO 2 layer adjacent to the SiN film 70 as shown in FIG. 10C. Distributed near the interface with the two films 60.
  • the stacked body having the structure shown in FIGS. 10A to 10C is considered as a semiconductor memory device having a SONOS structure
  • a predetermined voltage is applied to the polycrystalline silicon film 90b serving as a gate electrode with reference to the potential of the silicon substrate 90a. Apply a positive voltage.
  • electrons are accumulated in a channel formation region (not shown) to form an inversion layer, and a part of the charge in the inversion layer moves to the SiN film 70 via the SiO 2 film 60 by a tunnel phenomenon.
  • the electrons that have moved to the SiN film 70 are captured by traps formed therein, and data is stored.
  • the structure shown in FIG. 10B has the highest writing speed and the most excellent writing characteristics.
  • the structure shown in FIG. 10C in which the O 2 gas flow was performed twice in total immediately before and after the formation of the SiN film 70 is equivalent to the structure shown in FIG. 10A and shown in FIG. 10B. Compared to the structure, the writing speed is slow and only low writing characteristics can be obtained.
  • the trapping layer may be formed by introducing the O 2 gas anywhere as long as the SiN film 70 deposited by plasma CVD is in the film thickness direction, particularly 30% of the target film thickness. It is considered preferable to form the trap layer at a timing when it grows within a range of ⁇ 70%. In this way, traps can be concentrated in the SiN film 70. That is, the method of the present invention has an advantage that the existence distribution in the film thickness direction of the trap in the SiN film 70 can be controlled by adjusting the timing of introducing the O 2 gas. Preferably, by concentrating the traps in the vicinity of the center of the SiN film 70 in the film thickness direction, it is possible to create a structure in which a trap layer is formed at that position.
  • the SiN film 70 having a trap distribution peak in the film can be used, for example, as a charge storage layer in a nonvolatile semiconductor memory device, whereby excellent data writing characteristics can be obtained.
  • Test example 2 In this test, the SiN film 70 was subjected to 2-A) normal plasma CVD, 2-B) plasma CVD + O 2 gas flow (once; center in the film thickness direction), 2-C) plasma CVD + O 2 gas flow (twice). A central portion in the film thickness direction), 2-D) a film was formed by four film forming methods of thermal CVD. The conditions in each film forming method are as follows.
  • FIG. 11 shows the measurement result of ⁇ Vfb indicating the writing characteristics to the silicon nitride film formed under the above conditions.
  • the silicon nitride films of Experiment 2-B and Experiment 2-C obtained by introducing oxygen into the silicon nitride film by performing the O 2 gas flow are silicon nitride films by normal plasma CVD (Experiment 2-A).
  • Example 2-D silicon nitride films formed by thermal CVD
  • Experiment 2-B In comparison between Experiment 2-B and 2-C in which O 2 gas flow was performed at about half of the target film thickness (near the center in the film thickness direction), Experiment 2-B in which one O 2 gas flow was performed In comparison, in Experiment 2-C in which the O 2 gas flow was performed twice, ⁇ Vfb was larger and more traps were formed.
  • the O 2 gas flow is performed at least once, preferably at least twice during the plasma CVD process. It was shown that it is effective to form a trap layer in the silicon nitride film.
  • the O 2 gas flow is preferably performed when the silicon nitride film is formed within a range of 30 to 70% of the target film thickness.
  • FIG. 12 is a cross-sectional view showing a schematic configuration of the semiconductor memory device 201.
  • the semiconductor memory device 201 includes a p-type silicon substrate 101 as a semiconductor layer, a plurality of insulating films stacked on the p-type silicon substrate 101, and a gate electrode 103 formed thereon. have. Between the silicon substrate 101 and the gate electrode 103, a first insulating film 111, a second insulating film 112, and a third insulating film 113 as a tunnel oxide film are provided. Among these, the second insulating film 112 is a silicon nitride film and forms a charge storage layer in the semiconductor memory device 201.
  • a first source / drain 104 and a second source / drain 105 which are n-type diffusion layers are formed on the silicon substrate 101 at a predetermined depth from the surface so as to be located on both sides of the gate electrode 103.
  • a channel forming region 106 is formed between the two.
  • the semiconductor memory device 201 may be formed in a p-well or p-type silicon layer formed in the semiconductor substrate.
  • an n-channel MOS device will be described as an example, but a p-channel MOS device may be used. Accordingly, the contents described below can be applied to all n-channel MOS devices and p-channel MOS devices.
  • the first insulating film 111 is, for example, a silicon dioxide film (SiO 2 film) formed by oxidizing the surface of the silicon substrate 101 by a thermal oxidation method.
  • the second insulating film 112 is a silicon nitride film (SiN film) formed on the surface of the first insulating film 111.
  • the third insulating film 113 is a silicon dioxide film (SiO 2 film) deposited on the second insulating film 112 by, for example, a CVD method.
  • the third insulating film 113 functions as a block layer (barrier layer) between the electrode 103 and the second insulating film 112.
  • the gate electrode 103 is made of, for example, a polycrystalline silicon film formed by a CVD method, and functions as a control gate (CG) electrode.
  • the gate electrode 103 is a layer containing a metal such as tungsten (W), titanium (Ti), tantalum (Ta), copper (Cu), aluminum (Al), gold (Au), or platinum (Pt). May be.
  • the gate electrode 103 is not limited to a single layer.
  • tungsten (W), molybdenum (Mo), tantalum (Ta), and the like are used for the purpose of reducing the specific resistance of the gate electrode 103 and increasing the operation speed of the semiconductor memory device 201.
  • a laminated structure including titanium (Ti), platinum (Pt), silicide thereof, nitride, alloy and the like can also be used.
  • the gate electrode 103 is connected to a wiring layer (not shown).
  • the second insulating film 112 is a charge storage region that mainly stores charges. Therefore, when the second insulating film 112 is formed, the silicon nitride film forming method of the present invention is applied to control the trap amount and its distribution, thereby improving the data writing performance and data holding performance of the semiconductor memory device 201. Can be adjusted.
  • a silicon substrate 101 on which an element isolation film (not shown) is formed by a technique such as a LOCOS (Local Oxidation of Silicon) method or an STI (Shallow Trench Isolation) method is prepared.
  • a first insulating film 111 is formed.
  • the first insulating film 111 is a SiO 2 film.
  • a second insulating film 112 is formed on the first insulating film 111 by plasma CVD using the plasma CVD apparatus 100.
  • an O 2 gas flow is performed at a predetermined timing in the course of plasma CVD, thereby forming many traps in the film and reducing the trap distribution in the film thickness direction. Control. Thereby, the writing characteristics and reading characteristics of the semiconductor memory device 201 can be improved.
  • the third insulating film 113 is a SiO 2 film and can be formed by, for example, a CVD method. Note that it may be formed by low-temperature plasma CVD. Further, a polysilicon film, a metal layer, a metal silicide layer, or the like is formed on the third insulating film 113 by, for example, a CVD method to form a metal film that becomes the gate electrode 103.
  • the metal film and the third insulating film 113 to the first insulating film 111 are etched by using the patterned resist as a mask by using a photolithography technique, so that the patterned gate electrode 103 and the plurality of gate electrodes 103 are formed.
  • a gate laminated structure having an insulating film is obtained.
  • an n-type impurity is ion-implanted at a high concentration into the silicon surface adjacent to both sides of the gate stacked structure to form the first source / drain 104 and the second source / drain 105. In this way, the semiconductor memory device 201 having the structure shown in FIG. 12 can be manufactured.
  • the semiconductor memory device 201 having the above structure will be described.
  • the first source / drain 104 and the second source / drain 105 are held at 0 V with reference to the potential of the silicon substrate 101, and a predetermined positive voltage is applied to the gate electrode 103.
  • a predetermined positive voltage is applied to the gate electrode 103.
  • electrons are accumulated in the channel formation region 106 to form an inversion layer, and a part of the charge in the inversion layer moves to the second insulating film 112 through the first insulating film 111 by a tunnel phenomenon.
  • the electrons that have moved to the second insulating film 112 are captured by traps that are charge trapping centers formed therein, and data is accumulated.
  • a voltage of 0 V is applied to either the first source / drain 104 or the second source / drain 105 with reference to the potential of the silicon substrate 101, and a predetermined voltage is applied to the other. Further, a predetermined voltage is also applied to the gate electrode 103.
  • a voltage of 0 V is applied to both the first source / drain 104 and the second source / drain 105 with reference to the potential of the silicon substrate 101, and a negative magnitude of a predetermined magnitude is applied to the gate electrode 103. Apply voltage. By applying such a voltage, the charge held in the second insulating film 112 is extracted to the channel formation region 106 of the silicon substrate 101 through the first insulating film 111. As a result, the semiconductor memory device 201 returns to the erased state where the amount of accumulated electrons in the second insulating film 112 is low.
  • the method of writing, reading, and erasing information in the semiconductor memory device 201 is not limited, and writing, reading, and erasing may be performed by a method different from the above.
  • the structure having the second insulating film 112 as the charge storage region is taken as an example.
  • the method of the present invention is a semiconductor having a structure in which two or more silicon nitride films are stacked as the charge storage layer. The present invention can also be applied when manufacturing a memory device.
  • an RLSA type microwave plasma processing apparatus is used for plasma processing, but other types of plasma processing apparatuses such as an ICP plasma system, an ECR plasma system, a surface wave plasma system, a magnetron plasma system, etc. Other types of plasma processing apparatuses can be used.

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Abstract

L'invention porte sur un procédé de formation d'un film de nitrure de silicium qui comporte une étape de formation de film de nitrure de silicium à laquelle un plasma est généré par apport d'un gaz de traitement qui contient un gaz composé contenant du silicium et d'un gaz contenant de l'azote dans un contenant de traitement, et un film de nitrure de silicium est formé sur un sujet devant être traité, et une étape d'introduction de gaz contenant des atomes d'oxygène à laquelle la génération de plasma est stoppée lors de l'étape de formation de film de nitrure de silicium, un gaz contenant des atomes d'oxygène est introduit dans le contenant de traitement, et un piège est formé par exposition du film de nitrure de silicium au gaz contenant des atomes d'oxygène, tandis que le film est en cours de formation. L'étape de formation de film de nitrure de silicium peut comporter : une première étape à laquelle un film de nitrure de silicium est développé au moyen d'un plasma avant l'étape d'introduction de gaz contenant les atomes d'oxygène, et une seconde étape à laquelle un film de nitrure de silicium est développé au moyen d'un plasma après l'étape d'introduction de gaz contenant des atomes d'oxygène.
PCT/JP2010/055654 2009-03-31 2010-03-30 Procédé de formation d'un film de nitrure de silicium, procédé de fabrication d'un dispositif de mémoire à semi-conducteur et appareil de dépôt en phase vapeur assisté par plasma Ceased WO2010113928A1 (fr)

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WO2015108558A1 (fr) * 2014-01-17 2015-07-23 Applied Materials, Inc. Revêtement de chambre en ligne pour réguler l'écaillage de particules

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JPS6489371A (en) * 1987-09-29 1989-04-03 Matsushita Electronics Corp Manufacture of semiconductor storage device
JP2007250582A (ja) * 2006-03-13 2007-09-27 Fujitsu Ltd 不揮発性半導体記憶装置
WO2008123289A1 (fr) * 2007-03-26 2008-10-16 Tokyo Electron Limited Film de nitrure de silicium et dispositif de mémoire non volatile à semi-conducteurs

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JPS6489371A (en) * 1987-09-29 1989-04-03 Matsushita Electronics Corp Manufacture of semiconductor storage device
JP2007250582A (ja) * 2006-03-13 2007-09-27 Fujitsu Ltd 不揮発性半導体記憶装置
WO2008123289A1 (fr) * 2007-03-26 2008-10-16 Tokyo Electron Limited Film de nitrure de silicium et dispositif de mémoire non volatile à semi-conducteurs

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015108558A1 (fr) * 2014-01-17 2015-07-23 Applied Materials, Inc. Revêtement de chambre en ligne pour réguler l'écaillage de particules

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