WO2010113928A1 - Method for forming silicon nitride film, method for manufacturing semiconductor memory device, and plasma cvd apparatus - Google Patents

Method for forming silicon nitride film, method for manufacturing semiconductor memory device, and plasma cvd apparatus Download PDF

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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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silicon nitride
nitride film
gas
film
plasma cvd
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PCT/JP2010/055654
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French (fr)
Japanese (ja)
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辰夫 西田
稔 本多
準弥 宮原
敏雄 中西
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東京エレクトロン株式会社
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Publication of WO2010113928A1 publication Critical patent/WO2010113928A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76—Unipolar devices, e.g. field effect transistors
    • H01L29/772—Field effect transistors
    • H01L29/78—Field effect transistors with field effect produced by an insulated gate
    • H01L29/792—Field effect transistors with field effect produced by an insulated gate with charge trapping gate insulator, e.g. MNOS-memory 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
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/40—Electrodes ; Multistep manufacturing processes therefor
    • H01L29/401—Multistep manufacturing processes
    • H01L29/4011—Multistep manufacturing processes for data storage electrodes
    • H01L29/40117—Multistep manufacturing processes for data storage electrodes the electrodes comprising a charge-trapping insulator
    • 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
    • H01L21/0217—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
    • 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
    • H01L21/02271—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 decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition
    • H01L21/02274—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 decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition in the presence of a plasma [PECVD]

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.

Abstract

A method for forming a silicon nitride film is provided with a silicon nitride film forming step wherein plasma is generated by supplying a processing gas which contains a silicon-containing compound gas and a nitrogen-containing gas into a processing container, and a silicon nitride film is formed on a subject to be processed, and an oxygen atom-containing gas introducing step wherein the generation of plasma is stopped during the silicon nitride film forming step, an oxygen atom-containing gas is introduced into the processing container, and a trap is formed by exposing the silicon nitride film to the oxygen atom-containing gas, while the film is being formed. The silicon nitride film forming step can be provided with: a first step wherein a silicon nitride film is grown by means of plasma prior to the oxygen atom-containing gas introducing step, and a second step wherein a silicon nitride film is grown by means of plasma after the oxygen atom-containing gas introducing step.

Description

窒化珪素膜の成膜方法、半導体メモリ装置の製造方法およびプラズマＣＶＤ装置Method for forming silicon nitride film, method for manufacturing semiconductor memory device, and plasma CVD apparatus
　本発明は、窒化珪素膜の成膜方法、半導体メモリ装置の製造方法およびこれらの方法に用いられるプラズマＣＶＤ装置に関する。 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.
　現在、電気的書換え動作が可能なＥＥＰＲＯＭ（Ｅｌｅｃｔｒｉｃａｌｌｙ Ｅｒａｓａｂｌｅ ａｎｄ Ｐｒｏｇｒａｍｍａｂｌｅ ＲＯＭ）などに代表される不揮発性半導体メモリ装置としては、ＳＯＮＯＳ（Ｓｉｌｉｃｏｎ－Ｏｘｉｄｅ－Ｎｉｔｒｉｄｅ－Ｏｘｉｄｅ－Ｓｉｌｉｃｏｎ）型やＭＯＮＯＳ（Ｍｅｔａｌ－Ｏｘｉｄｅ－Ｎｉｔｒｉｄｅ－Ｏｘｉｄｅ－Ｓｉｌｉｃｏｎ）型と呼ばれる積層構造を有するものがある。これらのタイプの不揮発性半導体メモリ装置では、二酸化珪素膜（Ｏｘｉｄｅ）に挟まれた１層以上の窒化珪素膜（Ｎｉｔｒｉｄｅ）を電荷蓄積領域として情報の保持が行われる。つまり、上記不揮発性半導体メモリ装置では、半導体基板（Ｓｉｌｉｃｏｎ）とコントロールゲート電極（ＳｉｌｉｃｏｎまたはＭｅｔａｌ）との間に電圧を印加することによって、電荷蓄積領域の窒化珪素膜に電子を注入してデータを保存したり、窒化珪素膜に蓄積された電子を除去したりして、データの保存と消去の書換えを行っている。上記不揮発性半導体メモリ装置において、データ書込み特性は電荷蓄積領域である窒化珪素膜への電子の注入のしやすさと関係があり、特に窒化珪素膜中に存在する電荷捕獲中心（トラップ）と関係があると考えられる。 Currently, 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) type or a MONOS (Metal-Oxide-Metal) is used. Some have a laminated structure called a nitride-oxide-silicon type. In these types of nonvolatile semiconductor memory devices, information is held by using one or more silicon nitride films (Nitride) sandwiched between silicon dioxide films (Oxide) as a charge storage region. That is, in 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. In the non-volatile semiconductor memory device, 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.
　不揮発性半導体メモリ装置に関する技術として、特開平５－１４５０７８号公報には、窒化珪素膜とトップ酸化膜との界面のトラップ密度を増加させる目的で、これらの膜の中間部分にＳｉを多く含有する遷移層を設けることが記載されている。 As a technique related to a nonvolatile semiconductor memory device, 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.
　近年の半導体装置の高集積化に伴い、不揮発性半導体メモリ装置の素子構造も急速に微細化が進んでいる。不揮発性半導体メモリ装置を微細化するためには、個々の不揮発性半導体メモリ装置において、電荷蓄積層である窒化珪素膜のトラップを増加させ、データ書込み性能を高める必要がある。 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.
　しかしながら、減圧ＣＶＤ（Ｃｈｅｍｉｃａｌ Ｖａｐｏｒ Ｄｅｐｏｓｉｔｉｏｎ）法や熱ＣＶＤ法による成膜方法では、窒化珪素膜の形成過程で膜中のトラップ形成をコントロールすることは技術的に困難であった。また、プラズマＣＶＤ法では、処理容器内の処理圧力を高真空状態（例えば３Ｐａ以下）に設定してプラズマのイオン性を強めることにより、窒化珪素膜中に多くのトラップを形成することが可能であると考えられるが、ホットウォール（チャンバが加熱される）の処理容器内を高真空状態に維持するためには、高真空状態に耐えうる真空シール技術、耐圧容器、高性能の排気装置等が必要になるなど、装置負荷が増大し、コストも高くなるという欠点があった。また、イオンが多くなり高真空状態では、プラズマエネルギーが高くなるため、処理容器内の部品等へのスパッタリング作用が強くなり、重金属やパーティクル等による汚染の危険性が増加したり、窒化珪素膜形成におけるカバレッジ性能が低下したりするなど、プロセス的な側面でも問題を有していた。 However, it is technically difficult to control trap formation in the silicon nitride film during the film formation method by the low pressure CVD (Chemical Vapor Deposition) method or the thermal CVD method. Further, in the plasma 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. In order to maintain the inside of the processing chamber of the hot wall (the chamber is heated) in a high vacuum state, 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. In addition, the ion energy increases and the plasma energy increases in a high vacuum state, so that the sputtering effect on the components in the processing vessel becomes stronger, increasing the risk of contamination by heavy metals and particles, or forming a silicon nitride film There was also a problem in terms of process, such as a decrease in coverage performance.
　さらに、従来のプラズマＣＶＤ法で成膜した窒化珪素膜では、トラップは隣接する膜との界面に偏在することが多く、窒化珪素膜の膜厚方向におけるトラップの分布をコントロールすることは不可能であった。 Furthermore, in a silicon nitride film formed by a conventional plasma CVD method, traps are often unevenly distributed at the interface with adjacent films, and it is impossible to control the trap distribution in the film thickness direction of the silicon nitride film. there were.
　本発明は上記実情に鑑みてなされたものであり、その目的は、トラップが多く存在し、かつトラップの膜厚方向の分布を制御しながら、不揮発性半導体メモリ装置の電荷蓄積層として有用な窒化珪素膜をプラズマＣＶＤ法により成膜する方法を提供することである。 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.
　本発明の窒化珪素膜の成膜方法は、プラズマＣＶＤ装置の処理容器内で、プラズマＣＶＤ法により被処理体上に窒化珪素膜を堆積させる窒化珪素膜の成膜方法であって、
　前記処理容器内にシリコン含有化合物ガスと窒素含有ガスを含む処理ガスを供給してプラズマを生成させ、被処理体上に窒化珪素膜を形成する工程と、
　前記窒化珪素膜形成工程の途中で前記プラズマを停止させ、前記処理容器内に酸素原子含有ガスを導入し、形成途中の前記窒化珪素膜を酸素に曝してトラップを形成する酸素原子含有ガス導入工程と、を備えている。 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.
　本発明の窒化珪素膜の成膜方法において、前記窒化珪素膜形成工程は、前記酸素原子含有ガス導入工程の前に、前記プラズマにより窒化珪素膜を成長させる第１の工程と、前記酸素原子含有ガス導入工程の後で、前記プラズマにより窒化珪素膜を成長させる第２の工程と、を備えていることが好ましい。この場合、前記酸素原子含有ガス導入工程を、前記窒化珪素膜が目標膜厚に対して３０％以上７０％以下の範囲内の厚さに成長した段階で行うことが好ましい。 In the method for forming a silicon nitride film of the present invention, 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.
　本発明の窒化珪素膜の成膜方法では、前記酸素原子含有ガス導入工程を２回以上繰り返し行うことがより好ましい。 In the method for forming a silicon nitride film of the present invention, it is more preferable to repeat the oxygen atom-containing gas introduction step twice or more.
　また、本発明の窒化珪素膜の成膜方法では、前記プラズマＣＶＤ装置が、複数の孔を有する平面アンテナにより前記処理容器内にマイクロ波を導入してプラズマを生成するプラズマＣＶＤ装置であることが好ましい。 In the silicon nitride film forming method of the present invention, 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.
　本発明の半導体メモリ装置の製造方法は、シリコン層上に、トンネル酸化膜、電荷蓄積層としての窒化珪素膜、ブロック酸化珪素膜およびゲート電極が形成されてなる半導体メモリ装置の製造方法であって、
　前記電荷蓄積層としての窒化珪素膜の成膜が、
　プラズマＣＶＤ装置の処理容器内にシリコン含有化合物ガスと窒素含有ガスを含む処理ガスを供給してプラズマを生成させ、プラズマＣＶＤ法により被処理体上に窒化珪素膜を形成する工程と、
　前記窒化珪素膜形成工程の途中で前記プラズマを停止させ、前記処理容器内に酸素原子含有ガスを導入し、形成途中の前記窒化珪素膜を酸素に曝してトラップを形成する酸素原子含有ガス導入工程と、
を備えた窒化珪素膜の成膜方法により行われる。 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
　本発明のプラズマＣＶＤ装置は、
　被処理体を載置台に載置して収容する処理容器と、
　前記処理容器内に処理ガスを供給するガス供給装置と、
　前記処理容器内を減圧排気する排気装置と、
　前記処理容器内でプラズマＣＶＤ法により被処理体上に窒化珪素膜を堆積させる際に、前記処理容器内にシリコン含有化合物ガスと窒素含有ガスを含む処理ガスを供給してプラズマを生成させ、被処理体上に窒化珪素膜を形成する工程と、前記窒化珪素膜形成工程の途中で前記プラズマを停止させ、前記処理容器内に酸素原子含有ガスを導入し、形成途中の前記窒化珪素膜を酸素に曝してトラップを形成する酸素原子含有ガス導入工程と、を含む窒化珪素膜の成膜方法が行われるように制御する制御部と、
を備えている。 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;
When depositing a silicon nitride film on the object to be processed by plasma CVD in the processing container, a processing gas containing a silicon-containing compound gas and a nitrogen-containing gas is supplied into the processing container to generate plasma, In the process of forming a silicon nitride film on the processing body and in the middle of the silicon nitride film forming process, 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.
　本発明の窒化珪素膜の成膜方法によれば、プラズマＣＶＤ法による窒化珪素膜の堆積の途中で、一時的にプラズマを停止させ、前記処理容器内に酸素原子含有ガスを導入し、成膜途中の窒化珪素膜を酸素に曝すことにより、トラップの多い窒化珪素膜を形成することができる。また、酸素導入のタイミングを図ることによって、窒化珪素膜の膜厚方向におけるトラップの分布を簡単にコントロールすることができる。このように、本発明方法によれば、多くのトラップが所定の分布で存在する窒化珪素膜を、ガス系の制御による簡易な手法で製造できる。 According to the method for forming a silicon nitride film of the present invention, during the deposition of the silicon nitride film by the plasma CVD method, the plasma is temporarily stopped, the oxygen atom-containing gas is introduced into the processing container, and the film is formed. By exposing the intermediate silicon nitride film to oxygen, a silicon nitride film with many traps can be formed. In addition, the trap distribution in the film thickness direction of the silicon nitride film can be easily controlled by timing the introduction of oxygen. Thus, according to the method of the present invention, 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.
　また、本発明方法によって成膜された窒化珪素膜は、膜中にトラップが多く存在し、かつ、膜厚方向のトラップの分布が最適な位置にコントロールされているので、この膜を不揮発性半導体メモリ装置の電荷蓄積層として用いることにより、書き込み特性に優れた不揮発性半導体メモリ装置が得られる。 In addition, since 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.
窒化珪素膜の形成に適したプラズマＣＶＤ装置の一例を示す概略断面図である。It is a schematic sectional drawing which shows an example of the plasma CVD apparatus suitable for formation of a silicon nitride film. 平面アンテナの構造を示す図面である。It is drawing which shows the structure of a planar antenna. 制御部の構成を示す説明図である。It is explanatory drawing which shows the structure of a control part. 第１の実施の形態の窒化珪素膜の成膜方法のタイミングチャートを示す図面である。It is drawing which shows the timing chart of the film-forming method of the silicon nitride film of 1st Embodiment. 第１の実施の形態におけるプラズマＣＶＤ工程を説明する図面である。It is drawing explaining the plasma CVD process in 1st Embodiment. 第１の実施の形態における酸素原子含有ガス導入工程を説明する図面である。It is drawing explaining the oxygen atom containing gas introduction | transduction process in 1st Embodiment. 第１の実施の形態におけるプラズマＣＶＤ工程を説明する図面である。It is drawing explaining the plasma CVD process in 1st Embodiment. 第１の実施の形態における成膜後の窒化珪素膜の断面構造を説明する図面である。It is drawing explaining the cross-sectional structure of the silicon nitride film after film-forming in 1st Embodiment. 第２の実施の形態の窒化珪素膜の成膜方法のタイミングチャートを示す図面である。It is drawing which shows the timing chart of the film-forming method of the silicon nitride film of 2nd Embodiment. 窒化珪素膜の膜厚方向におけるＯ２の導入位置を示す説明図である。The position of the introduction of O 2 in the thickness direction of the silicon nitride film is an explanatory view showing a. 試験例で用いたＳＯＮＯＳ構造の積層体の説明図である。It is explanatory drawing of the laminated body of the SONOS structure used by the test example. 試験例１におけるΔＶｆｂの測定結果を示すグラフ図面である。6 is a graph showing the measurement result of ΔVfb in Test Example 1. 通常の条件でプラズマＣＶＤを行って形成した窒化珪素膜中のトラップの分布を示すエネルギーバンド図である。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. プラズマＣＶＤの途中に１回のＯ２ガスフローを行って形成した窒化珪素膜中のトラップの分布を示すエネルギーバンド図である。It is an energy band diagram showing the way to one of the O 2 trap distribution in the silicon nitride film formed by performing the gas flow of the plasma CVD. プラズマＣＶＤの前後に２回のＯ２ガスフローを行って形成した窒化珪素膜中のトラップの分布を示すエネルギーバンド図である。It is an energy band diagram showing the two O 2 trap distribution in the silicon nitride film formed by performing a gas flow before and after the plasma CVD. 試験例２におけるΔＶｆｂの測定結果を示すグラフ図面である。6 is a graph showing a measurement result of ΔVfb in Test Example 2. 本発明方法を適用可能な半導体メモリ装置の構成例を示す概略断面図である。It is a schematic sectional drawing which shows the structural example of the semiconductor memory device which can apply the method of this invention.
［第１の実施の形態］
　以下、本発明の実施の形態について図面を参照して詳細に説明する。図１は、本発明の窒化珪素膜の成膜方法に利用可能なプラズマＣＶＤ装置１００の概略構成を模式的に示す断面図である。 [First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 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.
　プラズマＣＶＤ装置１００は、複数のスロット状の孔を有する平面アンテナ、特にＲＬＳＡ（Radial Line Slot Antenna；ラジアルラインスロットアンテナ）にて処理容器内にマイクロ波を導入してプラズマを発生させることにより、高密度かつ低電子温度のマイクロ波励起プラズマを発生させ得るＲＬＳＡマイクロ波プラズマ処理装置として構成されている。プラズマＣＶＤ装置１００では、１×１０１０～５×１０１２／ｃｍ３のプラズマ密度で、かつ０．７～２ｅＶの低電子温度を有するプラズマによる処理が可能である。従って、プラズマＣＶＤ装置１００は、各種半導体装置の製造過程においてプラズマＣＶＤによる窒化珪素膜の成膜の目的で好適に利用できる。 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. In 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.
　プラズマＣＶＤ装置１００は、主要な構成として、気密に構成された処理容器１と、処理容器１内に処理ガスを供給するガス供給装置１８と、処理容器１内を減圧排気するための排気機構としての排気装置２４と、処理容器１の上部に設けられ、処理容器１内にマイクロ波を導入するマイクロ波導入機構２７と、少なくともこれらプラズマＣＶＤ装置１００の各構成部を制御する制御部５０と、を備えている。 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. An exhaust device 24, a microwave introduction mechanism 27 that is provided in the upper portion of the processing container 1 and introduces microwaves into the processing container 1, and a control unit 50 that controls at least each component of the plasma CVD apparatus 100, It has.
　処理容器１は、接地された略円筒状の容器により形成されている。なお、処理容器１は角筒形状の容器により形成してもよい。処理容器１は、アルミニウム等の材質からなる底壁１ａと側壁１ｂとを有している。 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.
　処理容器１の内部には、被処理体であるシリコンウエハ（以下、単に「ウエハ」と記す）Ｗを水平に支持するための載置台２が設けられている。載置台２は、熱伝導性の高い材質例えばＡｌＮ等のセラミックスにより構成されている。この載置台２は、排気室１１の底部中央から上方に延びる円筒状の支持部材３により支持されている。支持部材３は、例えばＡｌＮ等のセラミックスにより構成されている。 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.
　また、載置台２には、その外縁部をカバーし、ウエハＷをガイドするためのカバーリング４が設けられている。このカバーリング４は、例えば石英、ＡｌＮ、Ａｌ２Ｏ３、ＳｉＮ等の材質で構成された環状部材である。 Further, 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.
　また、載置台２には、温度調節機構としての抵抗加熱型のヒータ５が埋め込まれている。このヒータ５は、ヒータ電源５ａから給電されることにより載置台２を加熱して、その熱で被処理基板であるウエハＷを均一に加熱する。 Further, 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.
　また、載置台２には、熱電対（ＴＣ）６が挿入されている。この熱電対６によって温度計測を行うことにより、ウエハＷの加熱温度を例えば室温から９００℃までの範囲で制御可能となっている。 Further, a thermocouple (TC) 6 is inserted in the mounting table 2. By measuring the temperature with the thermocouple 6, the heating temperature of the wafer W can be controlled in a range from room temperature to 900 ° C., for example.
　また、載置台２には、ウエハＷを支持して昇降させるためのウエハ支持ピン（図示せず）を有している。各ウエハ支持ピンは、載置台２の表面に対して突没可能に設けられている。 Further, 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.
　処理容器１の底壁１ａの略中央部には、円形の開口部１０が形成されている。底壁１ａにはこの開口部１０と連通し、下方に向けて突出する排気室１１が連設されている。この排気室１１には、排気管１２が接続されており、この排気管１２を介して排気装置２４に接続されている。 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.
　処理容器１の上部には、処理容器１を開閉させる蓋体（リッド）としての機能を有するプレート１３が配置されている。プレート１３は開口を有しており、プレート１３の内周部は、内側（処理容器内空間）へ向けて突出し、環状の支持部１３ａを形成している。 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.
　処理容器１の上部にはガス導入部が設けられている。ガス導入部はプレート１３に形成され、少なくとも１種類のガスを導入する「第１のガス導入孔」としてのガス導入孔１４と、このガス導入孔１４の下方に形成され、少なくとも１種類のガスを導入する「第２のガス導入孔」としてのガス導入孔１５が設けられている。つまり、ガス導入部においてガス導入孔１４，１５は、上下２段に設けられている。各ガス導入孔は処理ガスを供給するガス供給装置１８にガス導入管を介して接続されている。なお、ガス導入孔１４および１５はノズル状またはシャワーヘッド状に設けてもよい。また、ガス導入孔１４とガス導入孔１５を単一のシャワーヘッドに設けてもよい。 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.
　また、処理容器１の側壁１ｂには、プラズマＣＶＤ装置１００と、これに隣接する搬送室（図示せず）との間で、ウエハＷの搬入出を行うための搬入出口１６と、この搬入出口１６を開閉するゲートバルブ１７とが設けられている。 Further, 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.
　ガス供給装置１８は、ガス供給源（例えば、窒素（Ｎ）含有ガス供給源１９ａ、酸素原子含有ガス供給源１９ｂ、シリコン（Ｓｉ）含有ガス供給源１９ｃ、不活性ガス供給源１９ｄおよびクリーニングガス供給源１９ｅ）と、ガス導入管（例えば、ガス導入管２０ａ、２０ｂ、２０ｃ、２０ｄ、２０ｅ）と、流量制御装置（例えば、マスフローコントローラ２１ａ、２１ｂ、２１ｃ、２１ｄ、２１ｅ）と、バルブ（例えば、開閉バルブ２２ａ，２２ｂ、２２ｃ、２２ｄ、２２ｅ）とを有している。窒素含有ガス供給源１９ａおよび酸素原子含有ガス供給源１９ｂは、上段のガス導入孔１４にガス導入管２０ａ，２０ｂを介して接続されている。また、Ｓｉ含有ガス供給源１９ｃ、不活性ガス供給源１９ｄおよびクリーニングガス供給源１９ｅは、下段のガス導入孔１５にガス導入管２０ｃ，２０ｄ，２０ｅを介して接続されている。クリーニングガス供給源１９ｅは、処理容器１内に付着した不必要な膜をクリーニングする際に使用される。なお、ガス供給装置１８は、上記以外の図示しないガス供給源として、例えば処理容器１内の雰囲気を置換する際に用いるパージガス供給源等を有していてもよい。 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. 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. In addition, 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.
　本発明では、酸素原子含有ガスとして、例えば酸素（Ｏ２）、オゾン（Ｏ３）、一酸化窒素（ＮＯ）、二酸化窒素（ＮＯ２）、一酸化二窒素（Ｎ２Ｏ）等を用いることができる。また、シリコン（Ｓｉ）含有ガスとして、例えばシラン（ＳｉＨ４）、ジシラン（Ｓｉ２Ｈ６）、テトラクロロシラン（ＳｉＣｌ４）、ヘキサクロロジシラン（Ｓｉ２Ｃｌ６）、ジクロロシラン（ＳｉＨ２Ｃｌ２）、トリクロロシラン（Ｓｉ２ＨＣｌ３）、トリシラン（Ｓｉ３Ｈ８）、トリシリルアミン（（ＳｉＨ３）３Ｎ）などを用いることができるが、その中でもシリコン原子と塩素原子からなる化合物のガス、例えばテトラクロロシラン（ＳｉＣｌ４）またはヘキサクロロジシラン（Ｓｉ２Ｃｌ６）を用いることが好ましい。また、窒素（Ｎ）含有ガスとしては、窒素ガス（Ｎ２）、アンモニア（ＮＨ３）、ヒドラジン（Ｎ２Ｈ４）、モノメチルヒドラジン（ＣＨ６Ｎ２）等を用いることができるが、水素を含有しないＮ２ガスを用いることが好ましい。シリコン原子と塩素原子からなるテトラクロロシラン（ＳｉＣｌ４）もしくはヘキサクロロジシラン（Ｓｉ２Ｃｌ６）とＮ２との組み合わせは、原料ガス分子中に水素を含有しないため、本発明において好ましく使用できる組み合わせである。さらに、不活性ガスとして、例えば希ガスを添加することがより好ましく、例えばＡｒガス、Ｋｒガス、Ｘｅガス、Ｈｅガスなどを用いることができる。パージガスとしては、Ａｒガス、窒素ガス等の不活性ガスが好ましい。 In the present invention, for example, oxygen (O 2 ), ozone (O 3 ), nitrogen monoxide (NO), nitrogen dioxide (NO 2 ), dinitrogen monoxide (N 2 O), or the like is used as the oxygen atom-containing gas. Can do. 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. As the nitrogen (N) -containing gas, 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. 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. . Furthermore, it is more preferable to add, for example, a rare gas as the inert gas, and for example, 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.
　Ｎ含有ガスおよび酸素原子含有ガスは、ガス供給装置１８の窒素含有ガス供給源１９ａおよび酸素原子含有ガス供給源１９ｂから、ガス導入管２０ａ、２０ｂを介してそれぞれガス導入孔１４に至り、ガス導入孔１４から処理容器１内に導入される。一方、Ｓｉ含有ガス、不活性ガスおよびクリーニングガスは、Ｓｉ含有ガス供給源１９ｃ、不活性ガス供給源１９ｄおよびクリーニングガス供給源１９ｅから、それぞれガス導入管２０ｃ、２０ｄ、２０ｅを介してガス導入孔１５に至り、処理容器１内に導入される。各ガス供給源に接続する各々のガス導入管２０ａ～２０ｅには、マスフローコントローラ２１ａ～２１ｅおよびその前後の開閉バルブ２２ａ～２２ｅが設けられている。このようなガス供給装置１８の構成により、供給されるガスの切替えや流量等の制御が出来るようになっている。なお、Ａｒガスなどのプラズマ励起用の希ガスは任意のガスであり、必ずしも処理ガス（Ｓｉ含有ガス、Ｎ含有ガス）と同時に供給する必要はないが、プラズマを安定化させる観点から添加することがより好ましい。特に、Ｓｉ含有ガスを処理容器内に安定した流量で供給するためのキャリアガスとしてＡｒガスを用いることがより好ましい。 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. On the other hand, 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. With such a configuration of the gas supply device 18, the supplied gas can be switched and the flow rate can be controlled. Note that 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. In particular, 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.
　排気装置２４は、ターボ分子ポンプなどの真空ポンプ（図示省略）を備えている。真空ポンプは、処理容器１の排気室１１に排気管１２を介して接続されている。この真空ポンプを作動させることにより、処理容器１内のガスは、均一に排気室１１の空間１１ａ内へ流れ、さらに空間１１ａから排気管１２を介して外部へ排気される。これにより、処理容器１内を均一に、例えば０．１３３Ｐａまで高速に減圧することが可能となっている。 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. By operating this vacuum pump, 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. Thereby, the inside of the processing container 1 can be uniformly decompressed at a high speed, for example, to 0.133 Pa.
　次に、マイクロ波導入機構２７の構成について説明する。マイクロ波導入機構２７は、主要な構成として、透過板２８、平面アンテナ３１、遅波材３３、金属製カバー部材３４、導波管３７およびマイクロ波発生装置３９を備えている。 Next, the configuration of the microwave introduction mechanism 27 will be described. 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.
　マイクロ波を透過する透過板２８は、プレート１３において内周側に張り出した支持部１３ａ上に配備されている。透過板２８は、誘電体、例えば石英や、セラミックス（Ａｌ２Ｏ３、ＡｌＮ等）から構成することができる。この透過板２８と支持部１３ａとの間は、シール部材２９を介して気密にシールされている。したがって、処理容器１内は気密に保持される。 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.
　平面アンテナ３１は、透過板２８の上方において、載置台２と対向するように設けられている。平面アンテナ３１は、円板状をなしている。なお、平面アンテナ３１の形状は、円板状に限らず、例えば四角板状でもよい。この平面アンテナ３１は、プレート１３の上に配置されている。 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.
　平面アンテナ３１は、例えば表面が金または銀メッキされた銅板、ニッケル板、ＳＵＳ板またはアルミニウム板から構成されている。平面アンテナ３１は、マイクロ波を放射する多数のスロット状のマイクロ波放射孔３２を有している。マイクロ波放射孔３２は、所定のパターンで平面アンテナ３１を貫通して形成されている。 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.
　マイクロ波放射孔３２は、例えば図２に示すように、細長い長方形状（スロット状）をなし、隣接する２つのマイクロ波放射孔が対をなしている。そして、典型的には隣接する一対のマイクロ波放射孔３２が「Ｔ」字形や「Ｖ」字形に所定のパターンで配置されている。また、このように形状に組み合わせて配置されたマイクロ波放射孔３２は、同心円状に配置されおり、マイクロ波が処理容器１内に同心円偏波で導入され、均一なプラズマが形成される。 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. Moreover, 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.
　マイクロ波放射孔３２の長さや配列間隔は、マイクロ波の波長（λｇ）に応じて決定される。例えば、マイクロ波放射孔３２の間隔は、λｇ／４からλｇとなるように配置される。図２においては、同心円状に形成された隣接するマイクロ波放射孔３２どうしの間隔をΔｒで示している。なお、マイクロ波放射孔３２の形状は、円形状、円弧状等の他の形状であってもよい。さらに、マイクロ波放射孔３２の配置形態は特に限定されず、同心円状のほか、例えば、螺旋状、放射状等に配置することもできる。 The length and arrangement interval of the microwave radiation holes 32 are determined according to the wavelength (λg) of the microwave. For example, the interval between the microwave radiation holes 32 is arranged to be λg / 4 to λg. In FIG. 2, the interval between adjacent microwave radiation holes 32 formed concentrically is indicated by Δr. Note that the microwave radiation hole 32 may have another shape such as a circular shape or an arc shape. Furthermore, 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.
　平面アンテナ３１の上面には、真空よりも大きい誘電率を有する遅波材３３が設けられている。この遅波材３３は、真空中ではマイクロ波の波長が長くなることから、マイクロ波の波長を短くしてプラズマを調整する機能を有している。 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.
　なお、平面アンテナ３１と透過板２８との間、また、遅波材３３と平面アンテナ３１との間は、それぞれ接触させても離間させてもよいが、接触させることが好ましい。 It should be noted that the 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.
　処理容器１の上部には、これら平面アンテナ３１および遅波材３３を覆うように、金属製カバー部材３４が設けられている。金属製カバー部材３４は、例えばアルミニウムやステンレス鋼等の金属材料によって形成され、平面アンテナ３１とともに偏平導波管を構成している。プレート１３の上端と金属製カバー部材３４とは、シール部材３５によりシールされている。金属製カバー部材３４の内部には、冷却水流路３４ａが形成されている。この冷却水流路３４ａに冷却水を通流させることにより、金属製カバー部材３４、遅波材３３、平面アンテナ３１および透過板２８を冷却できるようになっている。なお、金属製カバー部材３４は接地されている。 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. By allowing the cooling water to flow through the cooling water flow path 34a, the metal cover member 34, the slow wave member 33, the planar antenna 31 and the transmission plate 28 can be cooled. The metal cover member 34 is grounded.
　金属製カバー部材３４の上壁（天井部）の中央には、開口部３６が形成されており、この開口部３６には導波管３７が接続されている。導波管３７の他端側は、マッチング回路３８を介してマイクロ波を発生するマイクロ波発生装置３９が接続されている。 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.
　導波管３７は、上記金属製カバー部材３４の開口部３６から上方へ延出する断面円形状の同軸導波管３７ａと、この同軸導波管３７ａの上端部に接続された水平方向に延びる矩形導波管３７ｂとを有している。 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.
　同軸導波管３７ａの中心には内導体４１が延在している。この内導体４１は、金属製の銅等で構成され、その下端部において平面アンテナ３１の中心に接続固定されている。このような構造により、マイクロ波は、同軸導波管３７ａの内導体４１を伝播して平面アンテナ３１へ導入して、偏平導波管に放射状に効率よく均一に伝播される。 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.
　以上のような構成のマイクロ波導入機構２７により、マイクロ波発生装置３９で発生したマイクロ波が導波管３７を介して平面アンテナ３１へ伝搬され、さらに透過板２８を介して処理容器１内に導入されるようになっている。なお、マイクロ波の周波数としては、例えば２．４５ＧＨｚが好ましく用いられ、他に、８．３５ＧＨｚ、１．９８ＧＨｚ等を用いることもできる。 By the microwave introduction mechanism 27 having the above-described configuration, 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. As the microwave frequency, for example, 2.45 GHz is preferably used, and 8.35 GHz, 1.98 GHz, or the like can be used.
　プラズマＣＶＤ装置１００の各構成部は、制御部５０に接続されて制御される構成となっている。制御部５０は、コンピュータを有しており、例えば図３に示したように、ＣＰＵを備えたプロセスコントローラ５１と、このプロセスコントローラ５１に接続されたユーザーインターフェース５２および記憶部５３を備えている。プロセスコントローラ５１は、プラズマＣＶＤ装置１００において、例えば温度、圧力、ガス流量、マイクロ波出力などのプロセス条件に関係する各構成部（例えば、ヒータ電源５ａ、ガス供給装置１８、排気装置２４、マイクロ波発生装置３９など）を統括して制御する制御手段である。 Each component of the plasma CVD apparatus 100 is connected to and controlled by the control unit 50. 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. In the plasma CVD apparatus 100, 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.
　ユーザーインターフェース５２は、工程管理者がプラズマＣＶＤ装置１００を管理するためにコマンドの入力操作等を行うキーボードや、プラズマＣＶＤ装置１００の稼働状況を可視化して表示するディスプレイ等を有している。また、記憶部５３には、プラズマＣＶＤ装置１００で実行される各種処理をプロセスコントローラ５１の制御にて実現するための制御プログラム（ソフトウエア）や処理条件データ等が記録されたレシピが保存されている。 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. In addition, 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.
　そして、必要に応じて、ユーザーインターフェース５２からの指示等にて任意のレシピを記憶部５３から呼び出してプロセスコントローラ５１に実行させることで、プロセスコントローラ５１の制御下、プラズマＣＶＤ装置１００の処理容器１内で所望の処理が行われる。また、前記制御プログラムや処理条件データ等のレシピは、コンピュータ読み取り可能な記憶媒体、例えばＣＤ－ＲＯＭ、ハードディスク、フレキシブルディスク、フラッシュメモリ、ＤＶＤ、ブルーレイディスクなどに格納された状態のものを利用したり、あるいは、他の装置から、例えば専用回線を介して随時伝送させてオンラインで利用したりすることも可能である。 Then, if necessary, an arbitrary recipe is called from the storage unit 53 by an instruction from the user interface 52 and is executed by the process controller 51, so that the processing container 1 of the plasma CVD apparatus 100 is controlled under the control of the process controller 51. Desired processing. In addition, 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.
　次に、ＲＬＳＡ方式のプラズマＣＶＤ装置１００を用いる窒化珪素膜の成膜処理の手順について説明する。ここで一例として、Ｓｉ含有ガスとしてＳｉＣｌ４、Ｎ含有ガスとしてＮ２ガス、酸素原子含有ガスとしてＯ２ガスを用いる場合を挙げる。図４は、窒化珪素膜の成膜処理におけるマイクロ波、ＳｉＣｌ４ガス、Ｎ２ガスおよびＯ２ガスの導入のタイミングチャートである。まず、ゲートバルブ１７を開にして搬入出口１６からウエハＷを処理容器１内に搬入し、載置台２上に載置して加熱する。次に、処理容器１内を減圧排気しながら、ガス供給装置１８の窒素含有ガス供給源１９ａからガス導入孔１４を介してＮ２ガスを、また、Ｓｉ含有ガス供給源１９ｃおよび不活性ガス供給源１９ｄから、ガス導入孔１５を介してＳｉＣｌ４ガスおよび必要に応じてＡｒガスを、それぞれ所定の流量で処理容器１内に導入する（図４のｔ０）。そして、処理容器１内を所定の圧力に設定する。このときの条件については後述する。 Next, a procedure for forming a silicon nitride film using the RLSA type plasma CVD apparatus 100 will be described. As an example here, a case of using SiCl 4, N 2 gas as the N-containing gas, O 2 gas as an oxygen atom-containing gas as the Si-containing gas. 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. First, the gate valve 17 is opened, and the wafer W is loaded into the processing container 1 from the loading / unloading port 16, mounted on the mounting table 2 and heated. Next, while evacuating the inside of the processing container 1, 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. From the source 19d, 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). And the inside of the processing container 1 is set to a predetermined pressure. The conditions at this time will be described later.
　次に、マイクロ波発生装置３９で発生させた所定周波数例えば２．４５ＧＨｚのマイクロ波を、マッチング回路３８を介して導波管３７に導く（図４のｔ１）。導波管３７に導かれたマイクロ波は、矩形導波管３７ｂおよび同軸導波管３７ａを順次通過し、内導体４１を介して偏平導波管を構成する平面アンテナ３１に供給される。マイクロ波は、同軸導波管３７ａから平面アンテナ３１に向けて放射状に伝搬していく。そして、マイクロ波は、平面アンテナ３１のスロット状のマイクロ波放射孔３２から透過板２８を介して処理容器１内におけるウエハＷの上方空間に円偏波となって放射される。 Next, 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. Then, 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.
　平面アンテナ３１から透過板２８を透過して処理容器１に放射されたマイクロ波により、処理容器１内で電磁界が形成され、Ｎ２ガス、ＳｉＣｌ４ガス、Ａｒガスがそれぞれプラズマ化する。そして、プラズマ中で原料ガスの解離が効率的に進み、活性種（イオン、ラジカル等）の反応によって、窒化珪素（ＳｉＮ；ここで、ＳｉとＮとの組成比は必ずしも化学量論的に決定されず、成膜条件により異なる値をとる。以下、同様である）の薄膜が堆積される。このプラズマＣＶＤ工程は、図４のｔ１からｔ４までの区間で行われる。 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.
　本実施の形態の窒化珪素膜の成膜方法では、プラズマＣＶＤ工程による窒化珪素膜の成膜の途中で、所定時間（図４のｔ２からｔ３の区間）だけプラズマを停止させ、酸素原子含有ガス供給源１９ｂからガス導入孔１４を介してＯ２ガスなどの酸素原子含有ガスを処理容器１内に導入する酸素原子含有ガス導入工程（（ここでは、代表的にＯ２ガスを用いるため、「Ｏ２ガスフロー」と記すことがある）］）を備えている。このＯ２ガスフローでは、形成途中の窒化珪素膜を酸素に曝してＳｉ－Ｏ結合を生じさせ、トラップを形成することを目的とする。このように、本実施の形態の窒化珪素膜の形成方法では、Ｏ２ガスフローを介在させることにより、窒化珪素膜形成工程が、Ｏ２ガスフローの前に、プラズマにより窒化珪素膜を成長させる第１の工程（図４のｔ１からｔ２の区間）と、Ｏ２ガスフローの後で、プラズマにより窒化珪素膜を成長させる第２の工程（図４のｔ３からｔ４の区間）と、に分割される。つまり、プラズマにより第１の窒化珪素膜を形成し、第１の窒化珪素膜を酸素原子含有ガスに曝してトラップを形成し、その上にプラズマにより第２の窒化珪素膜を形成する。また、酸素原子含有ガス導入工程では、Ｓｉ－Ｏ結合を平面的に均一に点在させるように形成し、トラップが均一に点在されるようにしても良い。 In the silicon nitride film formation method of this embodiment, 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) that introduces 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. And “O 2 gas flow”))). 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. As described above, in the method for forming a silicon nitride film according to the present embodiment, 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.
　図５Ａ～図５Ｄは、プラズマＣＶＤ装置１００において行われる窒化珪素膜の成膜処理の工程を示すウエハＷの表面付近の断面図である。図５Ａに示したように、たとえば任意の下地層（ここではＳｉＯ２膜６０）の上に、プラズマＣＶＤ装置１００を使用してＳｉＣｌ４／Ｎ２ガスプラズマを生成させ、プラズマＣＶＤ法により窒化珪素膜（ＳｉＮ膜）７０ａを形成する（第１の工程）。この第１の工程におけるＳｉＮ膜７０ａの形成は、Ｓｉ含有ガスとしてＳｉＣｌ４ガス、窒素含有ガスとしてＮ２ガスを含む処理ガスを処理容器１内へ供給して以下の条件で行うことができる。この場合、希ガスを添加して安定したプラズマ生成と安定してガス供給しても良い。 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. As shown in 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.
　処理圧力は、０．１Ｐａ以上６．７Ｐａ以下の範囲内が好ましく、０．１Ｐａ以上４Ｐａ以下の範囲内がより好ましい。ＳｉＣｌ４を解離しやすくするため、処理圧力は、低いほどよい。また、処理圧力が６．７Ｐａを超えると、ＳｉＣｌ４ガスの解離が少なく、窒素との反応が進まず、十分な成膜が出来ないため好ましくない。 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. In order to facilitate the dissociation of SiCl 4 , the lower the processing pressure, the better. Further, if 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.
　また、合計処理ガス流量に対して、ＳｉＣｌ４ガスの流量比（ＳｉＣｌ４ガス／合計処理ガス流量の百分率）を０．０３％以上１５％以下とすることが好ましく、０．０３％以上１％以下とすることがより好ましい。なお、ＳｉＣｌ４ガスの流量は、０．５ｍＬ／ｍｉｎ（ｓｃｃｍ）以上１０ｍＬ／ｍｉｎ（ｓｃｃｍ）以下に設定することが好ましく、０．５ｍＬ／ｍｉｎ（ｓｃｃｍ）以上２ｍＬ／ｍｉｎ（ｓｃｃｍ）以下に設定することがより好ましい。なお、他の種類のＳｉ含有ガスを用いる場合も同様である。 Further, the total process gas flow, SiCl 4 gas flow rate of preferably to (SiCl 4 gas / total process gas flow rate percentage of) than 15% 0.03% or more, 0.03% or more 1% More preferably, it is as follows. 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.
　また、合計処理ガス流量に対して、Ｎ２ガス流量の比（Ｎ２ガス／合計処理ガス流量の百分率）を５％以上９９％以下とすることが好ましく、４０％以上９９％以下とすることがより好ましい。なお、Ｎ２ガスの流量は、１００ｍＬ／ｍｉｎ（ｓｃｃｍ）以上５０００ｍＬ／ｍｉｎ（ｓｃｃｍ）以下に設定することが好ましく、１００ｍＬ／ｍｉｎ（ｓｃｃｍ）以上２０００ｍＬ／ｍｉｎ（ｓｃｃｍ）以下に設定することがより好ましい。なお、他の種類のＮ含有ガスを用いる場合も同様である。 Further, 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.
　また、合計処理ガス流量に対して、Ａｒガスの流量比（例えばＡｒガス／合計処理ガス流量の百分率）を１０％以上９０％以下とすることが好ましく、１０％以上６０％以下とすることがより好ましい。なお、Ａｒ等の希ガスの流量は、１０ｍＬ／ｍｉｎ（ｓｃｃｍ）以上１０００ｍＬ／ｍｉｎ（ｓｃｃｍ）以下に設定することが好ましく、１０ｍＬ／ｍｉｎ（ｓｃｃｍ）以上５００ｍＬ／ｍｉｎ（ｓｃｃｍ）以下に設定することがより好ましい。 Further, the flow rate ratio of Ar gas (for example, the percentage of Ar gas / total process gas flow rate) 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.
　また、プラズマＣＶＤ処理の温度は、載置台２の温度を３００℃以上、好ましくは４００℃以上６００℃以下の範囲内に設定すればよい。 Further, 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.
　また、プラズマＣＶＤ装置１００におけるマイクロ波出力は、透過板２８の面積あたりのパワー密度として０．２５～２．５６Ｗ／ｃｍ２の範囲内とすることが好ましい。マイクロ波出力は、例えば５００～５０００Ｗの範囲内から目的に応じて上記範囲内のパワー密度になるように選択することができる。以上の条件で成膜することにより水素を含まない窒化珪素膜を均一に形成出来る。 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. By forming the film under the above conditions, a silicon nitride film containing no hydrogen can be formed uniformly.
　次に、図５Ｂに示したように、第１の工程後に、プラズマを停止して酸素原子含有ガス供給源１９ｂからＯ２ガスを短時間供給する（酸素原子含有ガス導入工程）。つまり、一時的（図４のｔ２からｔ３の間）に処理容器１内へのマイクロ波、ＳｉＣｌ４およびＮ２の供給を停止してプラズマを消火するとともに、処理容器１内にＯ２ガスを処理容器１内に導入して、第１の工程のプラズマＣＶＤ処理によって成膜されたＳｉＮ膜７０ａの表面を酸素に曝す。これによって、極微量の酸素をＳｉＮ膜７０ａの表面に導入できる。なお、酸素原子含有ガスとしては、Ｏ２ガスに代えて、例えば、Ｏ３ガス、ＮＯガス、ＮＯ２ガス、Ｎ２Ｏガス等を用いることも出来る。また、Ｏ２ガスフローの際、Ｏ２ガスフローの効果を損なわない範囲で、希ガスや窒素ガスなどをキャリアガスとしてＯ２ガスとともに導入することができる。例えば、図４ではＮ２ガスの供給を停止したが、Ｎ２ガスの供給は停止しなくてもよい。 Next, as shown in FIG. 5B, after the first step, 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. As the 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. Further, when the 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. For example, although the supply of N 2 gas is stopped in FIG. 4, the supply of N 2 gas may not be stopped.
　Ｏ２ガスフローは、ＳｉＮ膜７０ａの成長が膜厚方向において目標膜厚（ＳｉＮ膜７０の全膜厚）の中央付近に近づいたタイミング例えば目標膜厚の３０～７０％の範囲内でＯ２ガスフローを行うことが好ましく、４０～６０％の範囲内でＯ２ガスフローを行うことがより好ましい。このようにすれば、後述のように、不揮発性半導体メモリ装置における電荷蓄積層として用いた場合に優れたデータ書き込み特性が得られる。１回のＯ２ガスフローの時間は、例えば１０秒以上３００秒以下の範囲内が好ましく、３０秒以上１２０秒以下の範囲内がより好ましい。 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.
　Ｏ２ガスフローの際のＯ２ガス（酸素原子含有ガス）の流量は、例えば１０ｍＬ／ｍｉｎ（ｓｃｃｍ）以上２０００ｍＬ／ｍｉｎ（ｓｃｃｍ）以下が好ましく、１００ｍＬ／ｍｉｎ（ｓｃｃｍ）以上２０００ｍＬ／ｍｉｎ（ｓｃｃｍ）以下に設定することがより好ましく、１００ｍＬ／ｍｉｎ（ｓｃｃｍ）以上１０００ｍＬ／ｍｉｎ（ｓｃｃｍ）以下に設定することが望ましい。なお、他の種類の酸素原子含有ガスを用いる場合も同様である。 The flow rate of O 2 O 2 gas used in the gas flow (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. The same applies when other types of oxygen atom-containing gas are used.
　Ｏ２ガスフローの際の処理容器１内の圧力は、その前後に行われるプラズマＣＶＤの第１の工程（図４のｔ１からｔ２の区間）や第２の工程（図４のｔ３からｔ４の区間）と同等以上の圧力、例えば０．１～１３３．３Ｐａに設定することが好ましい。なお、Ｏ２ガスフローの際の圧力を窒化珪素膜形成時の圧力よりも高く設定することにより、処理容器１内におけるＯ２ガスのレジデンスタイムを長くし、Ｏ２ガスフローの効果をより高めることができる。 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.
　Ｏ２ガスフローが終了した後は、上記第１の工程と同じ条件でプラズマＣＶＤ処理を再開する（第２の工程）。すなわち、図５Ｃおよび図５Ｄに示したように、再び処理容器１内へ、マイクロ波、ＳｉＣｌ４およびＮ２の供給を再開してＳｉＣｌ４／Ｎ２ガスプラズマを生成させ、第１の工程で成膜した第１のＳｉＮ膜７０ａ上に第２のＳｉＮ膜７０ｂを堆積させて積層する。このようにして、目標膜厚例えば２ｎｍ～３００ｎｍの範囲内、好ましくは２ｎｍ～５０ｎｍの範囲内の膜厚でＳｉＮ膜７０を成膜することができる。ＳｉＮ膜７０が目標膜厚まで成長したら、マイクロ波発生装置３９のパワーをオフ（ＯＦＦ）にしてプラズマを停止させる（図４のｔ４）。その後、ＳｉＣｌ４とＮ２の供給を停止する（図４のｔ５）。以上のようにして、一枚のウエハＷへの成膜処理が終了するので、前記とは逆の手順でウエハＷをプラズマＣＶＤ装置１００から搬出する。 After the O 2 gas flow is completed, 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. In this way, 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. When the SiN film 70 has grown to the target film thickness, the power of the microwave generator 39 is turned off to stop the plasma (t 4 in FIG. 4 ). Thereafter, the supply of SiCl 4 and N 2 is stopped (t 5 in FIG. 4). As described above, since the film forming process on one wafer W is completed, the wafer W is unloaded from the plasma CVD apparatus 100 in the reverse procedure.
　図５Ｄでは、目標膜厚に成膜されたＳｉＮ膜７０において、Ｏ２ガスを導入した位置を破線により示している。Ｏ２ガスの導入は、プラズマを停止した状態で行うため、ＳｉＮ膜７０中への酸素の混入は微量であり、ＳｉＮ膜７０についてＴＥＭ（透過型電子顕微鏡）やＸＰＳ（Ｘ線光電子分光）分析などを行っても明確な層構造は観察されない。しかし、Ｏ２ガスフローによって、図５Ｄに示すＳｉＮ膜７０中のＯ２ガスの導入位置では、少なくとも二次元的にＳｉ－Ｏ結合がモノレイヤー（Monolayer）または数モノレイヤー程度形成されて高トラップ密度の領域（トラップ層）が形成されるものと考えられる。そして、目標膜厚（ＳｉＮ膜７０の全膜厚）の中央付近に近づいたタイミング例えば目標膜厚の３０～７０％の範囲内（好ましくは４０～６０％の範囲内）でＯ２ガスフローを行うことにより、Ｏ２ガスフローによるトラップ層を、ＳｉＮ膜７０の膜厚方向の中心から±２０％以内、好ましくは±１０％以内の厚みの範囲内に形成することが可能となり、ＳｉＮ膜７０を不揮発性半導体メモリ装置における電荷蓄積層として用いた場合に優れたデータ書き込み特性が得られる。 In 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. It is considered that a density region (trap layer) is formed. Then, 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. By doing so, 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. When data is used as a charge storage layer in a nonvolatile semiconductor memory device, excellent data writing characteristics can be obtained.
　以上の条件は、制御部５０の記憶部５３にレシピとして保存されている。そして、プロセスコントローラ５１がそのレシピを読み出してプラズマＣＶＤ装置１００の各構成部例えばヒータ電源５ａ、ガス供給装置１８、排気装置２４、マイクロ波発生装置３９などへ制御信号を送出することにより、所望の条件でのプラズマＣＶＤ処理が実現する。 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.
　以上のようにして得られるＳｉＮ膜７０は、トラップが多いため、例えば半導体メモリ装置の電荷蓄積層として使用した場合に、データ書き込み特性が改善される。また、例えば半導体メモリ装置の電荷蓄積領域として本発明の方法で形成した窒化珪素膜を適用することにより、優れたデータ書込み特性を備えた半導体メモリ装置を製造できる。 Since 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.
［第２の実施の形態］
　次に、図６および図７を参照しながら、本発明の第２の実施の形態にかかる窒化珪素膜の成膜方法について説明する。図６は、本実施の形態における窒化珪素膜の成膜処理におけるマイクロ波、ＳｉＣｌ４ガス、Ｎ２ガスおよびＯ２ガスの導入のタイミングチャートである。また、図７は、本実施の形態で成膜された窒化珪素膜におけるＯ２ガスの導入位置を示している。なお、本実施の形態でも、処理ガスとして、ＳｉＣｌ４ガスおよびＮ２ガスを用いるが、他のＳｉ含有ガスやＮ含有ガスを用いる場合についても同様である。 [Second Embodiment]
Next, a method for forming a silicon nitride film according to the second embodiment of the present invention will be described with reference to FIGS. 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. 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.
　第１の実施の形態では、プラズマＣＶＤ工程の間に、１回（図４のｔ２からｔ３の区間）だけＯ２ガスフローを行ったが、本実施の形態では、Ｏ２ガスフローを２回以上繰り返し行う点で第１の実施の形態と相違する。本実施の形態では、Ｏ２ガスフローを２回以上繰り返し行う点以外は、第１の実施の形態と同様であるため、以下では相違点を中心に説明する。図６および図７においても、第１の実施の形態と同一の構成には同一の符号を付して説明を省略する。 In the first embodiment, 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.
　本実施の形態におけるプラズマＣＶＤ工程は、図６のｔ１１からｔ１６までの区間で行われ、ＳｉＮ膜７０を形成する。そのプラズマＣＶＤ工程の途中で、所定時間（図６のｔ１２からｔ１３の区間およびｔ１４からｔ１５の区間）だけ、プラズマを停止してＯ２ガスフローを実施する。つまり、第１の工程（図６のｔ１１からｔ１２の区間）の後に、処理容器１内へのマイクロ波、ＳｉＣｌ４ガスおよびＮ２ガスの供給を停止して酸素原子含有ガス供給源１９ｂからＯ２ガスを処理容器１内へ短時間供給する（１回目のＯ２ガスフロー；図６のｔ１２からｔ１３の区間）。 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. Along the way of the plasma CVD process, 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).
　１回目のＯ２ガスフローが終了した後は、再び処理容器１内へマイクロ波、ＳｉＣｌ４ガスおよびＮ２ガスを供給し、第１の工程と同じ条件でプラズマＣＶＤ処理によるＳｉＮ膜７０の形成を再開する（第２の工程；図６のｔ１３からｔ１４の区間）。次に、再び処理容器１内へのマイクロ波、ＳｉＣｌ４ガスおよびＮ２ガスの供給を停止して酸素原子含有ガス供給源１９ｂからＯ２ガスを処理容器１内へ短時間供給する（２回目のＯ２ガスフロー；図６のｔ１４からｔ１５の区間）。なお、図６において、区間ｔ１２～ｔ１３と区間ｔ１４～ｔ１５との長さは、同じでもよいし、異なっていてもよく、それぞれ例えば１０～３００秒が好ましく、３０秒～１２０秒がより好ましい。 After the first O 2 gas flow is completed, 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). Next, 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). 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.
　２回目のＯ２ガスフローが終了した後は、再び処理容器１内へマイクロ波、ＳｉＣｌ４ガスおよびＮ２ガスを供給し、第１の工程と同じ条件でプラズマＣＶＤ処理を再開する（第３の工程；図６のｔ１５からｔ１６の区間）。この第３の工程は、工程時間以外の点では、実質的に第２の工程と同じである。なお、図示は省略するが、第１の工程の終了後１回目のＯ２ガスフローの前および第２の工程の終了後２回目のＯ２ガスフローの前に、それぞれパージガスを処理容器１内に導入して残留成膜ガスを除去することが好ましく、これによりＯ２ガスフローの効果を高めることができる。 After the second O 2 gas flow is completed, 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. Although not shown, first before the front and a second of the O 2 gas flow of the second after the end of the process of the first O 2 gas flow after the completion of the process, 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.
　図７に、プラズマＣＶＤ工程の間にＯ２ガスフローを２回行うことによって成膜されたＳｉＮ膜７０の膜厚方向におけるＯ２ガスの導入位置を示した。Ｏ２ガスフローを２回以上行う場合も、第１の実施の形態と同様に、ＳｉＮ膜７０の成長が膜厚方向において目標膜厚の１／２付近に近づいたタイミング例えば成膜の目標膜厚の３０～７０％の範囲内でＯ２ガスフローを行うことが好ましく、４０～６０％の範囲内でＯ２ガスフローを行うことがより好ましい。例えば、Ｏ２ガスフローを２回行う場合には、ＳｉＮ膜７０の成膜の目標膜厚の３０％に達した時点以降のタイミングで１回目のＯ２ガスフローを行い、成膜の目標膜厚の７０％に達する以前のタイミングで２回目のＯ２ガスフローを実施することがより好ましい。このようにすれば、Ｏ２ガスフローによるトラップ層を、ＳｉＮ膜７０の膜厚方向の中心から±２０％以内、好ましくは±１０％以内の厚みの範囲内に形成することが可能となり、このトラップを有するＳｉＮ膜７０を不揮発性半導体メモリ装置における電荷蓄積層として用いた場合に優れたデータ書き込み特性が得られる。 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%. For example, O 2 in the case of gas flow twice at a timing after the time of reaching 30% of the target thickness of the deposition of the SiN film 70 performs a first O 2 gas flow, the target film deposition More preferably, the second O 2 gas flow is performed at a timing before reaching 70% of the thickness. By doing so, it becomes possible to form the trap layer by the O 2 gas flow within a range of thickness within ± 20%, preferably within ± 10% from the center in the film thickness direction of the SiN film 70. When 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.
　以上のように、プラズマＣＶＤ工程の間にＯ２ガスフローを複数回行うことによってＳｉＮ膜７０中にトラップを層状に形成することができ、多くのトラップを有するＳｉＮ膜７０を形成することが出来る。このように多くのトラップを形成することにより、ＳｉＮ膜７０を不揮発性半導体メモリ装置の電荷蓄積層として利用する場合の書き込み特性を、Ｏ２ガスフローを１回だけ行う場合に比べて、より高めることができる。なお、Ｏ２ガスフローの回数は、２回に限らず、３回以上繰り返し行うことが可能である。Ｏ２ガスフローを３回以上繰り返し行う場合は、Ｏ２ガスフローと第２の工程をセットで繰り返すことができる。 As described above, 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. . By forming a large number of traps as described above, 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.
　本実施の形態における他の構成および効果は、第１の実施の形態と同様である。 Other configurations and effects in the present embodiment are the same as those in the first embodiment.
［試験例］
　次に、本発明の基礎となった実験データについて、説明する。まず、図８に示したようなＳＯＮＯＳ構造の試験用デバイスを作成した。図８における符号６０はＳｉＯ２膜、符号７０はトラップを有する窒化珪素膜、符号８０はブロックＳｉＯ２膜、符号９０ａは、単結晶シリコンからなるＳｉ基板、符号９０ｂは多結晶シリコン膜であり、ＳｉＮ膜７０が電荷蓄積層、多結晶シリコン膜９０ｂがコントロールゲート電極として機能する。この試験では、シリコン基板９０ａを接地電位として、多結晶シリコン膜９０ｂに所定範囲で電圧を変化させて印加した（フォワード）後、逆向きに変化させて印加し（リバース）、この往復の電圧印加過程におけるキャパシタンスを計測し、フォワードとリバースの各ＣＶカーブ（ヒステリシス曲線）から、ΔＶｆｂ（Ｖｆｂヒステリシス）を求めた。往復の電圧印加でＣＶカーブが変化するということは、電圧印加によってＳｉＮ膜７０中に正孔（ホール）がトラップされた結果、その電荷を打ち消すために電圧の変化が生じたものであり、Ｖｆｂヒステリシスが大きいほど、ＳｉＮ膜７０中にトラップが多く、書き込み特性に優れていることを示している。本試験では、図８の試験用デバイスに、４～６Ｖの範囲の電圧を印加してΔＶｆｂを計測し、データ書き込み特性を評価した。 [Test example]
Next, experimental data on which the present invention is based will be described. First, a test device having a SONOS structure as shown in FIG. 8 was prepared. 8, 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, and reference numeral 90b is a polycrystalline silicon film. The SiN film 70 functions as a charge storage layer, and the polycrystalline silicon film 90b functions as a control gate electrode. In this test, 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 ΔVfb (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. In this test, a voltage in the range of 4 to 6 V was applied to the test device of FIG. 8 to measure ΔVfb, and the data writing characteristics were evaluated.
試験例１：
　本試験では、ＳｉＮ膜７０を、１－Ａ）通常のプラズマＣＶＤ、１－Ｂ）プラズマＣＶＤ成膜＋Ｏ２ガスフロー（１回；膜厚方向中央部）、１－Ｃ）プラズマＣＶＤ成膜＋Ｏ２ガスフロー（２回；界面付近）、１－Ｄ）プラズマＣＶＤ（全区間Ｏ２ガス導入；ＳｉＯＮ膜形成）の４通りの成膜方法で成膜した。各成膜方法における条件は、以下のとおりである。 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.
１－Ａ）通常のプラズマＣＶＤによる窒化珪素膜の成膜：
　プラズマＣＶＤ装置１００を用いた。
　Ａｒガス流量；４０ｍＬ／ｍｉｎ（ｓｃｃｍ）
　Ｎ２ガス流量；４５０ｍＬ／ｍｉｎ（ｓｃｃｍ）
　ＳｉＣｌ４ガス流量；１ｍＬ／ｍｉｎ（ｓｃｃｍ）
　処理圧力；２．７Ｐａ（２０ｍＴｏｒｒ）
　処理温度（載置台）：４００℃
　マイクロ波パワー：３ｋＷ
　処理時間；１１０秒
　目標膜厚；８ｎｍ 1-A) Formation of silicon nitride film by normal plasma CVD:
A plasma CVD apparatus 100 was used.
Ar gas flow rate: 40 mL / min (sccm)
N 2 gas flow rate: 450 mL / min (sccm)
SiCl 4 gas flow rate; 1 mL / min (sccm)
Processing pressure: 2.7 Pa (20 mTorr)
Processing temperature (mounting table): 400 ° C
Microwave power: 3kW
Processing time: 110 seconds Target film thickness: 8 nm
１－Ｂ）プラズマＣＶＤ＋Ｏ２ガスフローによるトラップを有する窒化珪素膜（１回；膜厚方向中央部付近）：
i)１回目のプラズマＣＶＤ（窒化珪素膜形成）
　処理時間と目標膜厚以外は、上記１－Ａ）のプラズマＣＶＤと同じ条件でプラズマＣＶＤを行った。
　処理時間；５５秒
　目標膜厚；４ｎｍ
ii) Ｏ２ガスフロー（トラップ層形成）
　１回目のプラズマＣＶＤの後、プラズマを停止し、以下の条件でＯ２ガスフローを実施した。
　Ｏ２ガス流量；６００ｍＬ／ｍｉｎ（ｓｃｃｍ）
　処理時間；６０秒間
iii)２回目のプラズマＣＶＤ（窒化珪素膜形成）
　処理時間と目標膜厚以外は、上記１回目のプラズマＣＶＤと同様に実施した。
　処理時間；５５秒
　目標膜厚；４ｎｍ 1-B) Silicon nitride film having a trap by plasma CVD + O 2 gas flow (once; near the center in the film thickness direction):
i) First plasma CVD (silicon nitride film formation)
The plasma CVD was performed under the same conditions as the plasma CVD of 1-A) except for the processing time and the target film thickness.
Processing time: 55 seconds Target film thickness: 4 nm
ii) O 2 gas flow (trap layer formation)
After the first plasma CVD, the plasma was stopped and an O 2 gas flow was performed under the following conditions.
O 2 gas flow rate; 600 mL / min (sccm)
Processing time: 60 seconds
iii) Second plasma CVD (silicon nitride film formation)
Except for the processing time and the target film thickness, it was carried out in the same manner as the first plasma CVD.
Processing time: 55 seconds Target film thickness: 4 nm
１－Ｃ）プラズマＣＶＤ＋Ｏ２ガスフローによるトラップを有する窒化珪素膜（２回；界面付近）：
i)１回目のＯ２ガスフロー（界面トラップ層形成）
　プラズマＣＶＤの直前に、以下の条件でＯ２ガスフローを実施した。
　Ｏ２ガス流量；６００ｍＬ／ｍｉｎ（ｓｃｃｍ）
　処理時間；６０秒間
ii)プラズマＣＶＤ（窒化珪素膜形成）
　処理時間と目標膜厚も含め、上記１－Ａ）のプラズマＣＶＤと同じ条件でプラズマＣＶＤを行った。
iii)２回目のＯ２ガスフロー（界面トラップ層形成）
　プラズマＣＶＤの直後に、プラズマを停止し、以下の条件でＯ２ガスフローを実施した。
　Ｏ２ガス流量；６００ｍＬ／ｍｉｎ（ｓｃｃｍ）
　処理時間；６０秒間 1-C) Silicon nitride film having a trap by plasma CVD + O 2 gas flow (twice; near the interface):
i) First O 2 gas flow (interface trap layer formation)
Immediately before plasma CVD, an O 2 gas flow was performed under the following conditions.
O 2 gas flow rate; 600 mL / min (sccm)
Processing time: 60 seconds
ii) Plasma CVD (silicon nitride film formation)
Plasma CVD was performed under the same conditions as the plasma CVD of 1-A), including the processing time and target film thickness.
iii) Second O 2 gas flow (interface trap layer formation)
Immediately after plasma CVD, the plasma was stopped and an O 2 gas flow was performed under the following conditions.
O 2 gas flow rate; 600 mL / min (sccm)
Processing time: 60 seconds
１－Ｄ）プラズマＣＶＤ（全区間Ｏ２ガス導入；ＳｉＯＮ膜形成）：
　プラズマＣＶＤ装置１００を用いた。
　Ａｒガス流量；４０ｍＬ／ｍｉｎ（ｓｃｃｍ）
　Ｎ２ガス流量；４５０ｍＬ／ｍｉｎ（ｓｃｃｍ）
　Ｏ２ガス流量；１ｍＬ／ｍｉｎ（ｓｃｃｍ）
　ＳｉＣｌ４ガス流量；１ｍＬ／ｍｉｎ（ｓｃｃｍ）
　処理圧力；２．７Ｐａ（２０ｍＴｏｒｒ）
　処理温度（載置台）：５００℃
　マイクロ波パワー：３ｋＷ
　処理時間；１５０秒
　目標膜厚；８ｎｍ 1-D) 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
　図９に、上記各条件で成膜された窒化珪素膜（窒化酸化珪素膜を含む）への書き込み特性を示すΔＶｆｂの測定結果を示した。なお、図９の横軸はデータ書き込み時間であり、目盛の「１Ｅ－ｎ」、「１Ｅ＋ｎ」（ｎは数字）は、それぞれ「１×１０－ｎ」、「１×１０ｎ」を意味する（図１１も同様である）。目標膜厚の約半分（膜厚方向の中央付近）でＯ２ガスフローを実施した場合、酸素導入を一切行わない通常のプラズマＣＶＤによる窒化珪素膜と比べて高いΔＶｆｂを示した。一方、窒化珪素膜の形成前後にＯ２ガスフローを実施した場合や、全区間にわたり酸素導入を行った場合は、酸素導入を一切行わない通常のプラズマＣＶＤによる窒化珪素膜と比べて、ΔＶｆｂにほとんど差が見られなかった。 FIG. 9 shows the measurement result of ΔVfb 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). When 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 ΔVfb was shown in comparison with a normal silicon nitride film formed by plasma CVD without any oxygen introduction. On the other hand, when the O 2 gas flow is performed before and after the formation of the silicon nitride film, or when oxygen is introduced over the entire section, ΔVfb is higher than that of the normal plasma CVD silicon nitride film in which no oxygen is introduced. There was almost no difference.
　ここで、Ｏ２ガスフローの実施が窒化珪素膜中のトラップの分布に与える影響について図１０Ａ～図１０Ｃを参照しながら説明する。図１０Ａは、通常の条件でプラズマＣＶＤを行って窒化珪素膜を形成した場合、図１０Ｂは、プラズマＣＶＤ工程の途中で１回のＯ２ガスフローを行って窒化珪素膜を形成した場合、図１０Ｃは、ＳｉＮ膜７０の成膜の直前と直後のタイミングでそれぞれ（合計２回の）Ｏ２ガスフローを実施した場合における窒化珪素膜中のトラップの分布モデリングを、それぞれ、図８と同様の構成のＳＯＮＯＳ構造の積層体のエネルギーバンド図中に模式的に示したものである。なお、図１０Ｂは、ＳｉＮ膜７０の成膜を２回に分け、その間にＯ２ガスフローを１回実施した場合である。図１０Ａ～図１０Ｃ中の符号の意味は、図８と同様である。 Here, the effect of the O 2 gas flow on the trap distribution in the silicon nitride film will be described with reference to FIGS. 10A to 10C. FIG. 10A shows a case where a silicon nitride film is formed by performing plasma CVD under normal conditions, and 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. Note that 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.
　図１０Ａに示したように、通常のプラズマＣＶＤによってＳｉＮ膜７０を成膜した場合、トラップＴは隣接する下地層のＳｉＯ２膜６０との界面付近に集中して分布する。一方、ＳｉＮ膜７０の成膜途中で、Ｏ２ガスフローを１回実施した場合には、図１０Ｂに示したように、トラップＴは、ＳｉＮ膜７０の膜厚方向の中央付近（膜中）に集中して分布する。また、Ｏ２ガスフローをＳｉＮ膜７０の成膜の直前と直後のタイミングで計２回実施した場合には、図１０Ｃに示したように、トラップＴはＳｉＮ膜７０に隣接する下地層のＳｉＯ２膜６０との界面付近に分布する。なお、図１０Ｃにおいて、ＳｉＮ膜７０とブロックＳｉＯ２膜８０との界面では、ＳｉＮ膜７０の形成後にＯ２ガスフローを実施することにより生成したトラップが、ブロックＳｉＯ２膜８０の成膜の際にイニシャライズされて消滅してしまうため、当該界面には、ほとんどトラップＴが残らない。そのため、ＳｉＮ膜７０の成膜の直前と直後のタイミングで合計２回のＯ２ガスフローを実施した図１０Ｃは、トラップＴの分布が、結果的に図１０Ａと同様になるものと考えられる。 As shown in FIG. 10A, when the SiN film 70 is formed by normal plasma CVD, the traps T are concentrated and distributed in the vicinity of the interface with the adjacent SiO 2 film 60 of the underlying layer. On the other hand, when the O 2 gas flow is performed once during the formation of the SiN film 70, 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. Further, when the O 2 gas flow is performed twice in total immediately before and after the formation of the SiN film 70, 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. In FIG. 10C, at the interface between the SiN film 70 and the block SiO 2 film 80, traps generated by performing the O 2 gas flow after the formation of the SiN film 70 are formed when the block SiO 2 film 80 is formed. The trap T is hardly left at the interface. Therefore, in FIG. 10C in which the O 2 gas flow is performed twice in total immediately before and after the formation of the SiN film 70, it is considered that the distribution of the trap T becomes the same as that in FIG. 10A as a result.
　図１０Ａ～図１０Ｃに示した構造の積層体を、ＳＯＮＯＳ構造の半導体メモリ装置として考えた場合、データ書き込み時には、シリコン基板９０ａの電位を基準として、ゲート電極となる多結晶シリコン膜９０ｂに所定の正の電圧を印加する。このとき、チャネル形成領域（図示省略）に電子が蓄積されて反転層が形成され、その反転層内の電荷の一部がトンネル現象によりＳｉＯ２膜６０を介してＳｉＮ膜７０に移動する。ＳｉＮ膜７０に移動した電子は、その内部に形成されたトラップに捕獲され、データの蓄積が行われる。ここで、図１０Ａ～図１０Ｃに示した積層構造におけるデータ書き込み特性を比較すると、書き込み速度が速く、最も優れた書き込み特性を示すのは、図１０Ｂに示した構造である。一方、ＳｉＮ膜７０の成膜の直前と直後のタイミングで合計２回のＯ２ガスフローを実施した図１０Ｃに示した構造は、図１０Ａに示した構造と同等であり、図１０Ｂに示した構造に比較すると書き込み速度が遅く、低い書き込み特性しか得られない。 When the stacked body having the structure shown in FIGS. 10A to 10C is considered as a semiconductor memory device having a SONOS structure, when data is written, 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. At this time, 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. Here, when the data writing characteristics in the stacked structures shown in FIGS. 10A to 10C are compared, the structure shown in FIG. 10B has the highest writing speed and the most excellent writing characteristics. On the other hand, 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.
　ＳｉＮ膜７０の膜厚方向の中央付近でＯ２ガスを導入することにより図１０Ｂに示した構造とした場合、通常のプラズマＣＶＤによって形成された図１０Ａの構造と、ＳｉＯ２膜６０／ＳｉＮ膜７０界面のトラップ分布は同等である。しかし、図１０Ｂに示した構造では、ＳｉＯ２膜６０とＳｉＮ膜７０との界面付近のトラップ分布に隣接して、ＳｉＮ膜７０の膜厚方向の中央部により多くのトラップが分布していることから、ＳｉＯ２膜６０を通過した電荷は、ＳｉＮ膜７０の膜中のより深い位置（中央部付近）まで注入されやすくなる。その結果、図１０Ｂに示した構造では、図１０Ａの構造に比べ、書き込み速度が速くなり、優れたデータ書き込み性能が得られるものと考えられる。なお、ＳｉＮ膜７０の成膜の直前と直後のタイミングで合計２回のＯ２ガスフローを実施した図１０Ｃに示した構造の場合も、トラップＴの分布が、最終的に図１０Ａと同様になるため、図１０Ｂのような優れた書き込み特性は得られない。以上のように、図１０Ａ～図１０Ｃに示すようなトラップＴの分布の違いによって、図９に示す書き込み特性の試験結果を合理的に説明することができる。 When the structure shown in FIG. 10B is introduced by introducing O 2 gas near the center of the film thickness direction of the SiN film 70, the structure of FIG. 10A formed by normal plasma CVD, and the SiO 2 film 60 / SiN film The trap distribution at the 70 interface is equivalent. However, in the structure shown in FIG. 10B, many traps are distributed in the central portion in the film thickness direction of the SiN film 70 adjacent to the trap distribution near the interface between the SiO 2 film 60 and the SiN film 70. Therefore, the charge that has passed through the SiO 2 film 60 is likely to be injected to a deeper position (near the center) in the SiN film 70. As a result, in the structure shown in FIG. 10B, it is considered that the writing speed is higher than that in the structure of FIG. 10A, and excellent data writing performance can be obtained. In the case of the structure shown in FIG. 10C in which the O 2 gas flow is performed twice in total immediately before and after the formation of the SiN film 70, the trap T distribution is finally the same as in FIG. 10A. Therefore, the excellent writing characteristics as shown in FIG. 10B cannot be obtained. As described above, the test result of the write characteristics shown in FIG. 9 can be rationally explained by the difference in the distribution of the traps T as shown in FIGS. 10A to 10C.
　以上のことから、Ｏ２ガスの導入は、プラズマＣＶＤによって堆積させるＳｉＮ膜７０が膜厚方向の膜中であれば何処で行ってトラップ層を形成しても良く、特に目標膜厚の３０％～７０％の範囲内に成長したタイミングで行ってトラップ層を形成することが好ましいと考えられる。このようすれば、ＳｉＮ膜７０の膜中にトラップを集中的に分布させることができる。つまり、本発明方法では、Ｏ２ガスの導入のタイミングを調節することによって、ＳｉＮ膜７０の膜中におけるトラップの膜厚方向の存在分布を制御できるというメリットがある。好ましくは、トラップをＳｉＮ膜７０における膜厚方向の中央付近に集中させることによって、当該位置にあたかもトラップ層が形成されたような構造を作り出すことができる。そして、膜中にトラップの分布ピークを有するＳｉＮ膜７０は、例えば不揮発性半導体メモリ装置における電荷蓄積層として用いることによって、優れたデータ書き込み特性が得られる。 From the above, 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.
試験例２：
　本試験では、ＳｉＮ膜７０を、２－Ａ）通常のプラズマＣＶＤ、２－Ｂ）プラズマＣＶＤ＋Ｏ２ガスフロー（１回；膜厚方向中央部）、２－Ｃ）プラズマＣＶＤ＋Ｏ２ガスフロー（２回；膜厚方向中央部）、２－Ｄ）熱ＣＶＤの４通りの成膜方法で成膜した。各成膜方法における条件は、以下のとおりである。 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.
２－Ａ）通常のプラズマＣＶＤ：
　プラズマＣＶＤ装置１００を用いた。
　Ａｒガス流量；４０ｍＬ／ｍｉｎ（ｓｃｃｍ）
　Ｎ２ガス流量；４５０ｍＬ／ｍｉｎ（ｓｃｃｍ）
　ＳｉＣｌ４ガス流量；１ｍＬ／ｍｉｎ（ｓｃｃｍ）
　処理圧力；２．７Ｐａ（２０ｍＴｏｒｒ）
　処理温度（載置台）：４００℃
　マイクロ波パワー：３ｋＷ
　処理時間；１１０秒
　目標膜厚；８ｎｍ 2-A) Normal plasma CVD:
A plasma CVD apparatus 100 was used.
Ar gas flow rate: 40 mL / min (sccm)
N 2 gas flow rate: 450 mL / min (sccm)
SiCl 4 gas flow rate; 1 mL / min (sccm)
Processing pressure: 2.7 Pa (20 mTorr)
Processing temperature (mounting table): 400 ° C
Microwave power: 3kW
Processing time: 110 seconds Target film thickness: 8 nm
２－Ｂ）プラズマＣＶＤ＋Ｏ２ガスフロー（１回；膜厚方向中央部付近）：
i)１回目のプラズマＣＶＤ
　処理時間と目標膜厚以外は、上記１－Ａ）のプラズマＣＶＤと同じ条件でプラズマＣＶＤを行った。
　処理時間；５５秒
　目標膜厚；４ｎｍ
ii) Ｏ２ガスフロー 
　１回目のプラズマＣＶＤの後、プラズマを停止し、以下の条件でＯ２ガスフローを実施した。
　Ｏ２ガス流量；６００ｍＬ／ｍｉｎ（ｓｃｃｍ）
　処理時間；６０秒間
iii)２回目のプラズマＣＶＤ
　処理時間と目標膜厚以外は、上記１回目のプラズマＣＶＤと同様に実施した。
　処理時間；５５秒
　目標膜厚；４ｎｍ 2-B) Plasma CVD + O 2 gas flow (once; near the center in the film thickness direction):
i) First plasma CVD
The plasma CVD was performed under the same conditions as the plasma CVD of 1-A) except for the processing time and the target film thickness.
Processing time: 55 seconds Target film thickness: 4 nm
ii) O 2 gas flow
After the first plasma CVD, the plasma was stopped and an O 2 gas flow was performed under the following conditions.
O 2 gas flow rate; 600 mL / min (sccm)
Processing time: 60 seconds
iii) Second plasma CVD
Except for the processing time and the target film thickness, it was carried out in the same manner as the first plasma CVD.
Processing time: 55 seconds Target film thickness: 4 nm
２－Ｃ）プラズマＣＶＤ＋Ｏ２ガスフロー（２回；膜厚方向中央部付近）：
i)１回目のプラズマＣＶＤ
　処理時間と目標膜厚以外は、上記１－Ａ）のプラズマＣＶＤと同じ条件でプラズマＣＶＤを行った。
　処理時間；３４秒
　目標膜厚；２．６ｎｍ
ii)１回目のＯ２ガスフロー
　１回目のプラズマＣＶＤの後、プラズマを停止し、以下の条件でＯ２ガスフローを実施した。
　Ｏ２ガス流量；６００ｍＬ／ｍｉｎ（ｓｃｃｍ）
　処理時間；６０秒間
iii)２回目のプラズマＣＶＤ
　上記１回目のプラズマＣＶＤと同様に実施した。
　処理時間；３４秒
　目標膜厚；２．６ｎｍ
iv)２回目のＯ２ガスフロー
　２回目のプラズマＣＶＤの後、プラズマを停止し、以下の条件でＯ２ガスフローを実施した。
　Ｏ２ガス流量；６００ｍＬ／ｍｉｎ（ｓｃｃｍ）
　処理時間；６０秒間
v)３回目のプラズマＣＶＤ
　上記１回目のプラズマＣＶＤと同様に実施した。
　処理時間；３４秒
　目標膜厚；２．６ｎｍ 2-C) Plasma CVD + O 2 gas flow (twice; near the center in the film thickness direction):
i) First plasma CVD
The plasma CVD was performed under the same conditions as the plasma CVD of 1-A) except for the processing time and the target film thickness.
Processing time: 34 seconds Target film thickness: 2.6 nm
ii) First O 2 gas flow After the first plasma CVD, the plasma was stopped and an O 2 gas flow was performed under the following conditions.
O 2 gas flow rate; 600 mL / min (sccm)
Processing time: 60 seconds
iii) Second plasma CVD
It implemented similarly to the said 1st plasma CVD.
Processing time: 34 seconds Target film thickness: 2.6 nm
iv) Second O 2 gas flow After the second plasma CVD, the plasma was stopped and an O 2 gas flow was performed under the following conditions.
O 2 gas flow rate; 600 mL / min (sccm)
Processing time: 60 seconds
v) Third plasma CVD
It implemented similarly to the said 1st plasma CVD.
Processing time: 34 seconds Target film thickness: 2.6 nm
［熱ＣＶＤ条件］
　処理温度：７８０℃
　処理圧力；１３３Ｐａ
　ＳｉＨ２Ｃｌ２ガス＋ＮＨ３ガス；１００＋１０００ｍＬ／ｍｉｎ（ｓｃｃｍ）
　目標膜厚；８ｎｍ [Thermal CVD conditions]
Processing temperature: 780 ° C
Processing pressure: 133 Pa
SiH 2 Cl 2 gas + NH 3 gas; 100 + 1000 mL / min (sccm)
Target film thickness: 8nm
　図１１に、上記各条件で成膜された窒化珪素膜への書き込み特性を示すΔＶｆｂの測定結果を示した。Ｏ２ガスフローを実施して窒化珪素膜中に酸素を導入して得られた実験２－Ｂと実験２－Ｃの窒化珪素膜は、通常のプラズマＣＶＤによる窒化珪素膜（実験２－Ａ）や、熱ＣＶＤによる窒化珪素膜（実験２－Ｄ）に比べて、格段に高いΔＶｆｂを示した。また、目標膜厚の約半分（膜厚方向の中央付近）でＯ２ガスフローを実施した実験２－Ｂと２－Ｃの比較では、１回のＯ２ガスフローを行った実験２－Ｂよりも、２回のＯ２ガスフローを行った実験２－Ｃの方が、ΔＶｆｂが大きく、トラップが多く形成されていた。以上の結果から、半導体メモリ装置の電荷蓄積層として利用する場合の書き込み特性をより優れたものにするために、プラズマＣＶＤ工程の間で、Ｏ２ガスフローを１回以上、好ましくは２回以上行って窒化珪素膜中にトラップ層を形成することが有効であることが示された。好ましくは、窒化珪素膜の目標膜厚の３０～７０％の範囲内まで成膜した段階で、Ｏ２ガスフローすることが好ましい。 FIG. 11 shows the measurement result of ΔVfb 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). In addition, as compared with the silicon nitride film formed by thermal CVD (Experiment 2-D), a significantly higher ΔVfb was exhibited. 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, ΔVfb was larger and more traps were formed. From the above results, in order to improve the writing characteristics when used as a charge storage layer of a semiconductor memory device, 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. Preferably, 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.
［半導体メモリ装置の製造への適用例］
　次に、図１２を参照しながら、本実施の形態に係る窒化珪素膜の製造方法を半導体メモリ装置の製造過程に適用した例について説明する。図１２は、半導体メモリ装置２０１の概略構成を示す断面図である。半導体メモリ装置２０１は、半導体層としてのｐ型のシリコン基板１０１と、このｐ型のシリコン基板１０１上に積層形成された、複数の絶縁膜と、さらにその上に形成されたゲート電極１０３と、を有している。シリコン基板１０１とゲート電極１０３との間には、トンネル酸化膜としての第１の絶縁膜１１１と、第２の絶縁膜１１２と、第３の絶縁膜１１３とが設けられている。このうち、第２の絶縁膜１１２は窒化珪素膜であり、半導体メモリ装置２０１における電荷蓄積層を形成している。 [Example of application to the manufacture of semiconductor memory devices]
Next, an example in which the method for manufacturing a silicon nitride film according to the present embodiment is applied to a manufacturing process of a semiconductor memory device will be described with reference to FIG. 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.
　また、シリコン基板１０１には、ゲート電極１０３の両側に位置するように、表面から所定の深さでｎ型拡散層である第１のソース・ドレイン１０４および第２のソース・ドレイン１０５が形成され、両者の間はチャネル形成領域１０６となっている。なお、半導体メモリ装置２０１は、半導体基板内に形成されたｐウェルやｐ型シリコン層に形成されていてもよい。また、ここでは、ｎチャネルＭＯＳデバイスを例に挙げて説明を行うが、ｐチャネルＭＯＳデバイスで実施してもかまわない。従って、以下に記載する内容は、全てｎチャネルＭＯＳデバイス、及び、ｐチャネルＭＯＳデバイスに適用することができる。 In addition, 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. Here, 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.
　第１の絶縁膜１１１は、例えばシリコン基板１０１の表面を熱酸化法により酸化して形成された二酸化珪素膜（ＳｉＯ２膜）である。 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.
　第２の絶縁膜１１２は、第１の絶縁膜１１１の表面に形成された窒化珪素膜（ＳｉＮ膜）である。 The second insulating film 112 is a silicon nitride film (SiN film) formed on the surface of the first insulating film 111.
　第３の絶縁膜１１３は、第２の絶縁膜１１２上に、例えばＣＶＤ法により堆積させた二酸化珪素膜（ＳｉＯ２膜）である。この第３の絶縁膜１１３は、電極１０３と第２の絶縁膜１１２との間でブロック層（バリア層）として機能する。 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.
　ゲート電極１０３は、例えばＣＶＤ法により成膜された多結晶シリコン膜からなり、コントロールゲート（ＣＧ）電極として機能する。また、ゲート電極１０３は、例えばタングステン（Ｗ），チタン（Ｔｉ），タンタル（Ｔａ），銅（Ｃｕ），アルミニウム（Ａｌ），金（Ａｕ），白金（Ｐｔ）等の金属を含む層であってもよい。ゲート電極１０３は、単層に限らず、ゲート電極１０３の比抵抗を下げ、半導体メモリ装置２０１の動作速度を高速化する目的で、例えばタングステン（Ｗ）、モリブデン（Ｍｏ）、タンタル（Ｔａ）、チタン（Ｔｉ）、白金（Ｐｔ）それらのシリサイド、ナイトライド、合金等を含む積層構造にすることもできる。ゲート電極１０３は、図示しない配線層に接続されている。 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. For example, 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).
　また、半導体メモリ装置２０１において、第２の絶縁膜１１２は、主に電荷を蓄積する電荷蓄積領域である。従って、第２の絶縁膜１１２の形成に際して、本発明の窒化珪素膜の成膜方法を適用し、トラップ量とその分布を制御することによって、半導体メモリ装置２０１のデータ書き込み性能やデータ保持性能を調節できる。 In the semiconductor memory device 201, 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.
　ここでは代表的な手順を挙げて、本発明方法を半導体メモリ装置２０１の製造に適用した例について説明を行う。まず、ＬＯＣＯＳ（Ｌｏｃａｌ　Ｏｘｉｄａｔｉｏｎ　ｏｆ　Ｓｉｌｉｃｏｎ）法やＳＴＩ（Ｓｈａｌｌｏｗ　Ｔｒｅｎｃｈ　Ｉｓｏｌａｔｉｏｎ）法などの手法で素子分離膜（図示せず）が形成されたシリコン基板１０１を準備し、その表面に、例えば熱酸化法によって第１の絶縁膜１１１を形成する。第１の絶縁膜１１１はＳｉＯ２膜である。 Here, an example in which the method of the present invention is applied to the manufacture of the semiconductor memory device 201 will be described with a typical procedure. First, 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.
　次に、第１の絶縁膜１１１の上に、プラズマＣＶＤ装置１００を用いプラズマＣＶＤ法によって第２の絶縁膜１１２を形成する。 Next, a second insulating film 112 is formed on the first insulating film 111 by plasma CVD using the plasma CVD apparatus 100.
　第２の絶縁膜１１２を形成する場合は、プラズマＣＶＤの途中で所定のタイミングでＯ２ガスフローを実施することにより、膜中に多くのトラップを形成するとともに、膜厚方向におけるトラップの分布を制御する。これにより、半導体メモリ装置２０１の書き込み特性と読み出し特性を優れたものにすることができる。 In the case of forming the second insulating film 112, 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.
　次に、第２の絶縁膜１１２の上に、第３の絶縁膜１１３を形成する。この第３の絶縁膜１１３は、ＳｉＯ２膜であり、例えばＣＶＤ法によって形成することができる。なお、低温のプラズマＣＶＤで形成しても良い。さらに、第３の絶縁膜１１３の上に、例えばＣＶＤ法によってポリシリコン層や金属層、あるいは金属シリサイド層などを成膜してゲート電極１０３となる金属膜を形成する。 Next, a third insulating film 113 is formed over the second insulating film 112. 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.
　次に、フォトリソグラフィー技術を用い、パターン形成したレジストをマスクとして、前記金属膜、第３の絶縁膜１１３～第１の絶縁膜１１１をエッチングすることにより、パターン形成されたゲート電極１０３と複数の絶縁膜を有するゲート積層構造体が得られる。次に、ゲート積層構造体の両側に隣接するシリコン表面にｎ型不純物を高濃度にイオン注入し、第１のソース・ドレイン１０４および第２のソース・ドレイン１０５を形成する。このようにして、図１２に示した構造の半導体メモリ装置２０１を製造できる。 Next, 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. Next, 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.
　以上のような構造の半導体メモリ装置２０１の動作例について説明する。まず、データ書き込み時には、シリコン基板１０１の電位を基準として、第１のソース・ドレイン１０４および第２のソース・ドレイン１０５を０Ｖに保持し、ゲート電極１０３に所定の正の電圧を印加する。このとき、チャネル形成領域１０６に電子が蓄積されて反転層が形成され、その反転層内の電荷の一部がトンネル現象により第１の絶縁膜１１１を介して第２の絶縁膜１１２に移動する。第２の絶縁膜１１２に移動した電子は、その内部に形成された電荷捕獲中心であるトラップに捕獲され、データの蓄積が行われる。 An operation example of the semiconductor memory device 201 having the above structure will be described. First, at the time of data writing, 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. At this time, 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.
　データ読み出し時には、シリコン基板１０１の電位を基準として第１のソース・ドレイン１０４または第２のソース・ドレイン１０５のいずれか一方に０Ｖの電圧を印加し、もう一方に所定の電圧を印加する。さらに、ゲート電極１０３にも所定の電圧を印加する。このように電圧を印加することにより、第２の絶縁膜１１２内に蓄積された電荷の有無や、蓄積された電荷の量に応じ、チャネルの電流量やドレイン電圧が変化する。従って、このチャンネル電流またはドレイン電圧の変化を検出することによって、データを外部に読み出すことができる。 At the time of data reading, 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. By applying the voltage in this manner, the channel current amount and the drain voltage change depending on the presence or absence of charges accumulated in the second insulating film 112 and the amount of accumulated charges. Therefore, data can be read out by detecting this change in channel current or drain voltage.
　データの消去時には、シリコン基板１０１の電位を基準とし、第１のソース・ドレイン１０４および第２のソース・ドレイン１０５の両方に０Ｖの電圧を印加し、ゲート電極１０３に所定の大きさの負の電圧を印加する。このような電圧の印加によって、第２の絶縁膜１１２内に保持されていた電荷は第１の絶縁膜１１１を介してシリコン基板１０１のチャネル形成領域１０６に引き抜かれる。これにより、半導体メモリ装置２０１は、第２の絶縁膜１１２内の電子蓄積量が低い消去状態に戻る。 When erasing data, 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.
　なお、半導体メモリ装置２０１における情報の書き込み、読み出し、消去の方法は限定されるものではなく、上記とは異なる方式で書き込み、読み出しおよび消去を行ってもよい。また、図１２では、電荷蓄積領域として、第２の絶縁膜１１２を有する構成を例に挙げたが、本発明方法は、電荷蓄積層として２層以上の窒化珪素膜が積層された構造の半導体メモリ装置を製造する場合にも適用できる。 Note that 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. In FIG. 12, the structure having the second insulating film 112 as the charge storage region is taken as an example. However, 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.
　以上、本発明の実施形態を述べたが、本発明は上記実施形態に制約されることはなく、種々の変形が可能である。例えば、上記実施の形態では、プラズマ処理にＲＬＳＡ方式のマイクロ波プラズマ処理装置を用いたが、他の方式のプラズマ処理装置例えばＩＣＰプラズマ方式、ＥＣＲプラズマ方式、表面波プラズマ方式、マグネトロンプラズマ方式等の他の方式のプラズマ処理装置を用いることができる。 As mentioned above, although embodiment of this invention was described, this invention is not restrict | limited to the said embodiment, A various deformation | transformation is possible. For example, in the above embodiment, 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.

Claims (7)

  1. 　プラズマＣＶＤ装置の処理容器内で、プラズマＣＶＤ法により被処理体上に窒化珪素膜を堆積させる窒化珪素膜の成膜方法であって、
    　前記処理容器内にシリコン含有化合物ガスと窒素含有ガスを含む処理ガスを供給してプラズマを生成させ、被処理体上に窒化珪素膜を形成する窒化珪素膜形成工程と、
    　前記窒化珪素膜形成工程の途中で、前記プラズマを停止させ、前記処理容器内に酸素原子含有ガスを導入し、形成途中の前記窒化珪素膜を酸素原子含有ガスに曝してトラップを形成する酸素原子含有ガス導入工程と、
    を備えていることを特徴とする窒化珪素膜の成膜方法。     A silicon nitride film forming method for depositing a silicon nitride film on an object to be processed by a plasma CVD method in a processing vessel of a plasma CVD apparatus,
    A silicon nitride film forming step of 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;
    In the middle of the silicon nitride film forming step, the plasma is stopped, an oxygen atom-containing gas is introduced into the processing vessel, and the silicon nitride film being formed is exposed to the oxygen atom-containing gas to form oxygen atoms. A contained gas introduction process;
    A method for forming a silicon nitride film, comprising:
  2. 　前記窒化珪素膜形成工程は、前記酸素原子含有ガス導入工程の前に、前記プラズマにより窒化珪素膜を成長させる第１の工程と、
    　前記酸素原子含有ガス導入工程の後で、前記プラズマにより窒化珪素膜を成長させる第２の工程と、
    を備えていることを特徴とする請求項１に記載の窒化珪素膜の成膜方法。     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,
    A second step of growing a silicon nitride film by the plasma after the oxygen atom-containing gas introduction step;
    The method of forming a silicon nitride film according to claim 1, comprising:
  3. 　前記酸素原子含有ガス導入工程を、前記窒化珪素膜が目標膜厚に対して３０％以上７０％以下の範囲内の厚さに成長した段階で行うことを特徴とする請求項２に記載の窒化珪素膜の成膜方法。 3. The nitriding according to claim 2, wherein the oxygen atom-containing gas introduction step is performed when the silicon nitride film has grown to a thickness within a range of 30% to 70% with respect to a target film thickness. A method for forming a silicon film.
  4. 　前記酸素原子含有ガス導入工程を２回以上繰り返し行うことを特徴とする請求項１に記載の窒化珪素膜の形成方法。 The method for forming a silicon nitride film according to claim 1, wherein the oxygen atom-containing gas introduction step is repeated twice or more.
  5. 　前記プラズマＣＶＤ装置が、複数の孔を有する平面アンテナにより前記処理容器内にマイクロ波を導入してプラズマを生成するプラズマＣＶＤ装置であることを特徴とする請求項１に記載の窒化珪素膜の成膜方法。 2. The silicon nitride film composition according to claim 1, wherein the plasma CVD apparatus is a plasma CVD apparatus that generates plasma by introducing a microwave into the processing container using a planar antenna having a plurality of holes. Membrane method.
  6. 　シリコン層上に、トンネル酸化膜、電荷蓄積層としての窒化珪素膜、ブロック酸化珪素膜およびゲート電極が形成されてなる半導体メモリ装置の製造方法であって、
    　前記電荷蓄積層としての窒化珪素膜の成膜が、
    　プラズマＣＶＤ装置の処理容器内にシリコン含有化合物ガスと窒素含有ガスを含む処理ガスを供給してプラズマを生成させ、プラズマＣＶＤ法により被処理体上に窒化珪素膜を形成する窒化珪素膜形成工程と、
    　前記窒化珪素膜形成工程の途中で前記プラズマを停止させ、前記処理容器内に酸素原子含有ガスを導入し、形成途中の前記窒化珪素膜を酸素原子含有ガスに曝してトラップを形成する酸素原子含有ガス導入工程と、
    を備えた窒化珪素膜の成膜方法により行われることを特徴とする半導体メモリ装置の製造方法。     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,
    A silicon nitride film forming step of forming a silicon nitride film on a target object by plasma CVD by supplying a processing gas containing a silicon-containing compound gas and a nitrogen-containing gas into a processing vessel of a plasma CVD apparatus; ,
    In the middle of the silicon nitride film forming step, the plasma is stopped, an oxygen atom-containing gas is introduced into the processing vessel, and the silicon nitride film being formed is exposed to an oxygen atom-containing gas to form a trap. A gas introduction process;
    A method for manufacturing a semiconductor memory device, comprising: forming a silicon nitride film comprising:
  7. 　被処理体を載置台に載置して収容する処理容器と、
    　前記処理容器内に処理ガスを供給するガス供給装置と、
    　前記処理容器内を減圧排気する排気装置と、
    　前記処理容器内でプラズマＣＶＤ法により被処理体上に窒化珪素膜を堆積させる際に、前記処理容器内にシリコン含有化合物ガスと窒素含有ガスを含む処理ガスを供給してプラズマを生成させ、被処理体上に窒化珪素膜を形成する窒化珪素膜形成工程と、前記窒化珪素膜形成工程の途中で前記プラズマを停止させ、前記処理容器内に酸素原子含有ガスを導入し、形成途中の前記窒化珪素膜を酸素に曝してトラップを形成する酸素原子含有ガス導入工程と、を含む窒化珪素膜の成膜方法が行われるように制御する制御部と、
    を備えたことを特徴とするプラズマＣＶＤ装置。     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;
    When depositing a silicon nitride film on the object to be processed by plasma CVD in the processing container, a processing gas containing a silicon-containing compound gas and a nitrogen-containing gas is supplied into the processing container to generate plasma, A silicon nitride film forming step for forming a silicon nitride film on the processing body, and the plasma is stopped in the middle of the silicon nitride film forming step, an oxygen atom-containing gas is introduced into the processing container, and the nitriding in the middle of the formation A control unit that controls the film formation method of the silicon nitride film to include an oxygen atom-containing gas introduction step of forming a trap by exposing the silicon film to oxygen;
    A plasma CVD apparatus comprising:
PCT/JP2010/055654 2009-03-31 2010-03-30 Method for forming silicon nitride film, method for manufacturing semiconductor memory device, and plasma cvd apparatus WO2010113928A1 (en)

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