WO2011010655A1 - Method for forming coating film which is composed of α-tantalum, and the coating film - Google Patents

Method for forming coating film which is composed of α-tantalum, and the coating film Download PDF

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WO2011010655A1
WO2011010655A1 PCT/JP2010/062221 JP2010062221W WO2011010655A1 WO 2011010655 A1 WO2011010655 A1 WO 2011010655A1 JP 2010062221 W JP2010062221 W JP 2010062221W WO 2011010655 A1 WO2011010655 A1 WO 2011010655A1
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Prior art keywords
tantalum
substrate
film
gas
process gas
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PCT/JP2010/062221
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French (fr)
Japanese (ja)
Inventor
周司 小平
知之 吉浜
恒吉 鎌田
和正 堀田
純一 濱口
茂雄 中西
聡 豊田
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株式会社アルバック
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Priority to JP2011523670A priority Critical patent/JPWO2011010655A1/en
Publication of WO2011010655A1 publication Critical patent/WO2011010655A1/en

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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34—Sputtering
    • C23C14/3457—Sputtering using other particles than noble gas ions
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C23C14/14—Metallic material, boron or silicon
    • 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
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
    • H01L21/283—Deposition of conductive or insulating materials for electrodes conducting electric current
    • H01L21/285—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation
    • H01L21/28506—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers
    • H01L21/28512—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers on semiconductor bodies comprising elements of Group IV of the Periodic System
    • H01L21/2855—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers on semiconductor bodies comprising elements of Group IV of the Periodic System by physical means, e.g. sputtering, evaporation

Definitions

  • the present invention relates to a method for forming a film made of ⁇ -tantalum and the film.
  • a barrier metal layer is provided between the base and the wiring, thereby preventing deterioration of the wiring caused by diffusion of the conductive material constituting the wiring toward the base.
  • the barrier metal layer is formed by forming a thin film made of a metal or a metal compound on a substrate by a PVD method such as sputtering or a vapor phase growth method.
  • a barrier metal layer made of tantalum nitride (TaN), tantalum (Ta), and a combination of them is formed on a base made of a low dielectric constant (low-k) material or silicon oxide (SiO 2 ).
  • a semiconductor element having a copper wiring is disclosed (Patent Document 1).
  • a thin film Ta used as a conventional barrier metal layer has a problem of high specific resistance. This is because the tantalum thin film contains tantalum ( ⁇ tantalum) whose crystal system is cubic and tantalum ( ⁇ tantalum) whose crystal system is tetragonal, and it is difficult to sufficiently reduce the specific resistance. .
  • An aspect according to the present invention provides a method of forming a film made of ⁇ -tantalum on a substrate, and a film made of ⁇ -tantalum formed by the film-forming method, which is made of the ⁇ -tantalum from the substrate. It is an object of the present invention to provide a film made of ⁇ -tantalum in which a conductor or a semiconductor is arranged on at least one of the front and rear sides of the film made of ⁇ -tantalum as viewed in the film direction.
  • the film forming method of ⁇ tantalum according to the aspect of the present invention is a method of forming a film of ⁇ tantalum on a substrate by using a sputtering method, and is a first method including an inert gas and a nitrogen gas.
  • a process gas is introduced into the vacuum chamber, and after the introduction of the first process gas, a first gas comprising at least one of an inert gas and a nitrogen gas is formed so as to have a nitrogen partial pressure at which a film made of ⁇ -tantalum is formed.
  • a film made of ⁇ -tantalum is formed on the substrate by introducing the process gas 2 into the vacuum chamber and controlling the plasma.
  • the film formation method of the ⁇ -tantalum after the first process gas is introduced, an underlayer made of tantalum nitride is formed on the substrate, and an underlayer made of tantalum nitride is formed on the substrate, A film made of ⁇ -tantalum is formed on the substrate.
  • the method for forming a film made of ⁇ -tantalum is characterized in that silicon is used as the base material.
  • the method for forming a film made of ⁇ -tantalum is characterized in that silicon oxide or quartz is used as the substrate material.
  • the film made of ⁇ tantalum in the aspect according to the present invention is a film made of ⁇ tantalum formed by the film forming method, and the film made of ⁇ tantalum in the direction from the substrate toward the film made of ⁇ tantalum.
  • a conductor or a semiconductor is disposed at at least one of the front position and the rear position.
  • the coating made of ⁇ tantalum according to the embodiment of the present invention is a barrier having a low specific resistance, in which a conductor or semiconductor is disposed on at least one of the coating made of ⁇ tantalum when the coating made of ⁇ tantalum is viewed from the substrate.
  • the conductor or semiconductor material can be prevented from diffusing into the substrate, and the adhesion of the conductor or semiconductor to the substrate can be enhanced.
  • FIG. 3A is an X-ray diffraction spectrum of a film made of ⁇ -tantalum shown in FIG. 3A. Sectional drawing of the film which consists of (beta) tantalum and (alpha) tantalum formed into a film on the base
  • FIG. 3A is an X-ray diffraction spectrum of a film made of ⁇ -tantalum shown in FIG. 3A. Sectional drawing of the film which consists of (beta) tantalum and (alpha) tantalum formed into a film on the base
  • FIG. 4A is an X-ray diffraction spectrum of a film made of ⁇ -tantalum and ⁇ -tantalum shown in FIG. 4A. Sectional drawing of the film which consists of (beta) tantalum formed into a film on the base
  • the film formation method of ⁇ tantalum is a method of forming a film of ⁇ tantalum on a substrate using a sputtering method, and is a first process gas including an inert gas and a nitrogen gas.
  • a second process gas consisting of an inert gas and / or nitrogen gas so as to achieve a nitrogen partial pressure at which a film made of ⁇ -tantalum is formed and step A introducing ⁇ Step B for forming a coating made of ⁇ -tantalum on the substrate.
  • sputtering method a general sputtering method capable of forming a metal thin film on a substrate can be applied, and examples thereof include sputtering methods such as magnetron sputtering and reactive sputtering.
  • a target in the sputtering method a target made of Ta (hereinafter referred to as Ta target) is used.
  • the pressure in the sputtering method can be a pressure used in a known sputtering method, for example, 1.0 ⁇ 10 ⁇ 6 Pa or more and 400 Pa or less.
  • the substrate temperature in the sputtering method may be a temperature used in a known sputtering method, and may be, for example, from ⁇ 50 ° C. to 600 ° C.
  • the substrate is not particularly limited as long as it is made of a material that can withstand the temperature at the time of film formation by sputtering.
  • a substrate made of silicon a substrate made of silicon oxide, a substrate made of quartz, a substrate made of metal, etc. Is mentioned.
  • the substrate may be one in which another thin film or the like is previously formed as a base layer on the substrate.
  • the inert gas is not particularly limited as long as it is an inert gas used for sputtering, and examples thereof include argon (Ar), krypton (Kr), helium (He), and the like. Of these, Ar, which is generally easily available and inexpensive, is more preferable.
  • the nitrogen gas (N 2 ) may be a nitrogen gas having a purity generally used in sputtering, and the higher the purity, the better.
  • ⁇ tantalum According to the film formation method of ⁇ tantalum according to the present embodiment, it is possible to form a film of ⁇ tantalum on the substrate, which has been difficult in the past.
  • a thin film made of tantalum was formed by sputtering using a Ta target in an inert gas atmosphere such as Ar. It was a thin film made of ⁇ -tantalum and ⁇ -tantalum.
  • a film made of ⁇ -tantalum can be formed on the substrate by performing the following step A and the following step B in order.
  • the film-forming method of the film which consists of alpha tantalum of this embodiment is demonstrated by the 1st aspect and the 2nd aspect.
  • a cathode electrode 4 is fixed to the ceiling of the vacuum chamber 10, and a Ta target 5 is disposed on the surface thereof.
  • a DC power supply 9 for applying a negative voltage is connected to the cathode electrode 4.
  • a magnetic circuit 8 made of a permanent magnet is provided at the back surface position of the cathode electrode 4 outside the vacuum chamber 10, and the magnetic flux formed by the magnetic circuit 8 penetrates the cathode electrode 4 and the Ta target 5, and the Ta target 5
  • a leakage magnetic field is formed on the surface. When sputtering is performed, electrons are trapped in the leakage magnetic field, and the plasma is densified.
  • a substrate electrode 6 is provided on the bottom surface of the vacuum chamber 10, and a substrate 7 is disposed on the surface of the substrate electrode 6 so as to face the Ta target 5 substantially in parallel.
  • the substrate electrode 6 is connected to a high frequency power source 13 for applying a high frequency bias power.
  • the base electrode 6 is provided with a heater 11 electrically insulated by an insulating portion 11a, and the temperature of the base 7 can be adjusted to ⁇ 50 ° C. to 600 ° C.
  • the vacuum chamber 10 is provided with a gas inlet 2 and a vacuum exhaust 3.
  • a gas cylinder of Ar and nitrogen gas constituting the process gas is connected to the gas inlet 2 so that the respective flow rates can be adjusted individually.
  • a vacuum pump is connected to the vacuum exhaust port 3 (a gas cylinder and a vacuum pump are not shown).
  • the step A in the present embodiment is a step of introducing a first process gas composed of an inert gas and a nitrogen gas into the vacuum chamber 10.
  • the flow rate of the first process gas introduced into the vacuum chamber 10 from the gas inlet 2 is the sum of the flow rate of the inert gas and the flow rate of the nitrogen gas.
  • the flow rate of the inert gas in the first process gas is not particularly limited and can be, for example, 1.0 sccm or more and 30 sccm or less.
  • the flow rate of the nitrogen gas in the first process gas is not particularly limited and can be, for example, 0.01 sccm or more and 30 sccm or less.
  • the sccm is a unit expressed in cm 3 / min (1 atm, 0 ° C.).
  • step A by introducing the first process gas in advance in step A, the gas flow rate and pressure in the vacuum chamber 10 can be stabilized, and a film made of ⁇ -tantalum is sputtered in step B described later.
  • the generation of plasma during formation can be stabilized.
  • the pressure in the vacuum chamber 10 into which the first process gas is introduced in the step A is preferably a pressure range suitable for the sputtering method of 1.0 ⁇ 10 ⁇ 6 Pa to 400 Pa, more preferably 0.001 Pa. It is 10 Pa or less, More preferably, it is 0.01 Pa or more and 1.0 Pa or less. When the pressure is in the above range, a film made of ⁇ -tantalum can be efficiently formed on the substrate in Step B described later.
  • the plasma is controlled by setting a second process gas made of an inert gas and / or a nitrogen gas so as to have a nitrogen partial pressure at which a film made of ⁇ -tantalum is formed. Is a step of forming a film of ⁇ -tantalum on the substrate.
  • the second process gas is put into the vacuum chamber 10 under the atmosphere of the first process gas introduced in the step A, and the partial pressure of nitrogen in the vacuum chamber 10 is changed to that of ⁇ tantalum. It shall be suitable for formation.
  • the flow rate of the second process gas introduced into the vacuum chamber 10 from the gas inlet 2 is the sum of the flow rate of the inert gas and the flow rate of the nitrogen gas.
  • the flow rate of the inert gas is preferably 5.0 sccm or more and 20 sccm or less, more preferably 5.0 sccm or more and 15 sccm or less, and further preferably 8.0 sccm or more and 12 sccm or less.
  • the flow rate of nitrogen gas is preferably 0.01 sccm or more and 5.0 sccm or less, more preferably 0.05 sccm or more and 2.5 sccm or less, and further preferably 0.1 sccm or more and 1.0 sccm or less.
  • the sccm is a unit expressed in cm 3 / min (1 atm, 0 ° C.).
  • the flow rate ratio between the inert gas of the second process gas and the nitrogen gas introduced into the vacuum chamber 10 (the flow rate of the inert gas: the flow rate of the nitrogen gas) is preferably 2000: 1 to 1: 1, : 1 to 2: 1 is more preferable, and 120: 1 to 8: 1 is more preferable.
  • the above range includes the flow ratio at both ends.
  • the inside of the vacuum chamber 10 can be set to a nitrogen partial pressure at which a film made of ⁇ -tantalum is formed.
  • the preferable ranges of the partial pressures of the inert gas and the nitrogen gas in the vacuum chamber 10 in which the second process gas is set are as follows.
  • the partial pressure of the inert gas in the vacuum chamber 10 in which the second process gas is set is preferably 0.03 Pa or more and 5.0 Pa or less, more preferably 0.03 Pa or more and 1.0 Pa or less, and more preferably 0.03 Pa or more. 0.5 Pa or less is more preferable.
  • the nitrogen partial pressure (nitrogen gas partial pressure) in the vacuum chamber 10 in which the second process gas is set is preferably 0.001 Pa or more and 0.02 Pa or less, more preferably 0.001 Pa or more and 0.01 Pa or less, and 0 More preferably 0.003 Pa or more and 0.007 Pa or less.
  • the DC power source 9 When the inside of the vacuum chamber 10 is stabilized at the nitrogen partial pressure at which the ⁇ tantalum film is formed, the DC power source 9 is started, a negative voltage is applied to the cathode electrode 4 to start discharging, and the surface of the Ta target 5 Sputtering can be performed by generating plasma. At this time, a high frequency bias may be applied to the base electrode 6 by a high frequency power source 13.
  • the power of the DC power supply 9 is preferably 5.0 kW or more and 30 kW or less, more preferably 10 kW or more and 25 kW or less, and most preferably 15 kW or more and 20 kW or less because the effect of the present embodiment is excellent.
  • the frequency is preferably 1.0 MHz to 13.56 MHz because the effect of the present embodiment is excellent.
  • a film made of ⁇ -tantalum can be formed on the substrate 7.
  • the thickness of the film made of ⁇ -tantalum to be formed can be set to a desired thickness by appropriately adjusting the sputtering time.
  • the film can be formed with a thickness of 1 nm to 200 ⁇ m.
  • the surface of the substrate 7 on which the ⁇ -tantalum film is formed is not particularly limited, and may be, for example, the surface of a substrate made of silicon or the surface of a substrate made of silicon oxide. Further, a surface on which a thin film made of TaN or the like is previously formed as a base layer may be used.
  • ⁇ Second aspect> A second mode of the film forming method of ⁇ -tantalum according to this embodiment will be described with reference to the sputtering apparatus 1 shown in FIG.
  • the configuration of the sputtering apparatus 1 is the same as the configuration of the sputtering apparatus 1 described in the first aspect.
  • the step A in the present embodiment is a step of introducing a first process gas composed of an inert gas and a nitrogen gas into the vacuum chamber 10.
  • the flow rate of the first process gas introduced into the vacuum chamber 10 from the gas inlet 2 is the sum of the flow rate of the inert gas and the flow rate of the nitrogen gas.
  • the flow rate of the inert gas in the first process gas is preferably 5.0 sccm or more and 20 sccm or less, more preferably 5.0 sccm or more and 15 sccm or less, and most preferably 8.0 sccm or more and 12 sccm or less.
  • the flow rate of nitrogen gas in the first process gas is preferably 15 sccm or more and 60 sccm or less, more preferably 20 sccm or more and 40 sccm or less, and most preferably 25 sccm or more and 35 sccm or less.
  • the sccm is a unit expressed in cm 3 / min (1 atm, 0 ° C.).
  • the flow rate ratio between the inert gas and nitrogen gas of the first process gas introduced into the vacuum chamber 10 is preferably 1: 2 to 1: 5. : 2 to 1: 4 is more preferable, and 1: 2.5 to 1: 3.5 is most preferable.
  • the above range includes the flow ratio at both ends.
  • the pressure in the vacuum chamber 10 into which the first process gas has been introduced in the step A can be 1.0 ⁇ 10 ⁇ 6 Pa or more and 400 Pa or less, and more preferably, 0.1. It is 01 Pa or more and 10 Pa or less, More preferably, it is 0.1 Pa or more and 1.0 Pa or less.
  • the nitrogen partial pressure of the vacuum chamber 10 into which the first process gas is introduced in the step A is preferably a nitrogen partial pressure when a thin film made of known TaN is formed by a sputtering method. 0.03 Pa to 5.0 Pa, preferably 0.03 Pa to 1.0 Pa, and more preferably 0.03 Pa to 0.5 Pa.
  • a base layer made of TaN can be formed on the substrate 7.
  • sputtering method sputtering can be performed by starting the DC power supply 9, applying a negative voltage to the cathode electrode 4 to start discharge, and generating plasma on the surface of the Ta target 5. At this time, a high frequency bias may be applied to the base electrode 6 by a high frequency power source 13.
  • the plasma is controlled by setting a second process gas made of an inert gas and / or a nitrogen gas so as to have a nitrogen partial pressure at which a film made of ⁇ -tantalum is formed.
  • a film made of ⁇ -tantalum is formed on the substrate 7.
  • the inert gas is put as the second process gas in the vacuum chamber 10 under the first process gas atmosphere introduced in the step A, and the nitrogen partial pressure in the vacuum chamber 10 is continuously lowered.
  • a film made of ⁇ -tantalum can be formed on the substrate 7 by sputtering as described above.
  • the method of continuously lowering the nitrogen partial pressure in the vacuum chamber 10 is performed by stopping the inflow of nitrogen gas and flowing in only the inert gas when setting the second process gas. be able to.
  • the same amount of gas as the inflowing gas is exhausted to keep the pressure of the vacuum chamber 10 constant. Therefore, by switching to the inflow of only the inert gas, the nitrogen gas remaining in the vacuum chamber 10 is changed. The concentration can be lowered continuously. Therefore, when the inflow of only the inert gas is continued, the nitrogen partial pressure in the vacuum chamber 10 finally becomes substantially zero.
  • the coating made of ⁇ -tantalum passes through the nitrogen partial pressure formed on the substrate 7. That is, when the nitrogen partial pressure in the vacuum chamber 10 is a nitrogen partial pressure at which a TaN film can be formed, sputtering is started to form a TaN underlayer on the substrate 7, and the nitrogen partial pressure is continuously maintained as described above. By continuing the sputtering while lowering, the film of ⁇ tantalum starts to be formed on the substrate 7 when the film of ⁇ tantalum reaches the nitrogen partial pressure formed on the substrate 7.
  • sputtering is continued while further reducing the nitrogen partial pressure, whereby a film made of ⁇ -tantalum is formed on the previously formed film made of ⁇ -tantalum.
  • the nitrogen partial pressure finally becomes substantially zero, but even in this case, the formation of the film made of ⁇ -tantalum is continued by continuing the sputtering.
  • the thickness of the film made of ⁇ -tantalum to be formed can be set to a desired thickness by appropriately adjusting the sputtering time.
  • the film can be formed with a thickness of 1 nm to 200 ⁇ m.
  • the pressure in the vacuum chamber 10 in which the second process gas is set in the step B is preferably a pressure range suitable for the sputtering method of 1.0 ⁇ 10 ⁇ 6 Pa to 400 Pa, more preferably 0.001 Pa. It is 10 Pa or less, More preferably, it is 0.01 Pa or more and 1.0 Pa or less.
  • the flow rate of the second process gas that flows into the vacuum chamber 10 from the gas inlet 2 is the sum of the flow rate of the inert gas and the flow rate of the nitrogen gas.
  • the flow rate of the inert gas is preferably 5.0 sccm or more and 20 sccm or less, more preferably 5.0 sccm or more and 15 sccm or less, and further preferably 8.0 sccm or more and 12 sccm or less.
  • the flow rate of nitrogen gas is preferably 0 sccm or more and 0.5 sccm or less, more preferably 0 sccm or more and 0.25 sccm or less, and most preferably 0 sccm.
  • the sccm is a unit expressed in cm 3 / min (1 atm, 0 ° C.).
  • the power of the DC power source 9 is preferably 5.0 kW or more and 30 kW or less, more preferably 10 kW or more and 25 kW or less, and most preferably 15 kW or more and 20 kW or less because the effect of the present embodiment is excellent.
  • the frequency is preferably 1.0 MHz or more and 13.56 MHz or less because the effect of the present embodiment is excellent.
  • a base layer made of TaN can be formed on the substrate 7, and a film made of ⁇ -tantalum can be further formed thereon.
  • the substrate 7 is covered with a shutter or the like until the nitrogen partial pressure in the vacuum chamber 10 becomes a nitrogen partial pressure at which a film made of ⁇ -tantalum is formed. It is only necessary to prevent the base layer made of
  • the surface of the substrate 7 on which the ⁇ -tantalum film is formed is not particularly limited, and may be, for example, the surface of a substrate made of silicon or the surface of a substrate made of silicon oxide. Further, a surface on which a thin film made of TaN or the like is previously formed as a base layer may be used.
  • the nitrogen partial pressure at which a film made of ⁇ -tantalum is formed is obtained. . That is, as shown in FIG. 2, it was found that the specific resistance of the Ta thin film formed when the nitrogen gas was flow rate F in FIG. 2 indicates the flow rate of nitrogen gas introduced into the vacuum chamber 10 (unit: sccm). The vertical axis of FIG. 2 indicates that the vacuum chamber 10 is sufficiently stabilized at the nitrogen gas flow rate indicated on the horizontal axis. The specific resistance (unit: ⁇ ⁇ cm) of the Ta thin film formed by sputtering is shown. The formed Ta thin film has a thickness of about 100 mm, and the underlying layer is TaN.
  • the Ta thin film formed at a nitrogen flow rate of 5 sccm or more in FIG. 2 is a thin film made of TaN.
  • the nitrogen flow rate is 5 sccm or less
  • the specific resistance of the formed Ta thin film is lower than that of the TaN thin film, and the specific resistance decreases most when the nitrogen flow rate F is in the range of 0.1 sccm to 1.0 sccm.
  • the Ta thin film formed in this nitrogen flow rate range was a thin film made of ⁇ -tantalum.
  • Example 1 and Comparative Examples 1 and 2 sputtering was performed using the sputtering apparatus 1 shown in FIG.
  • Example 1 A process gas is adjusted in the order of steps A, C, B, and D shown in Table 1 to control plasma, and a base layer 22 made of TaN is formed on the silicon wafer 21 by sputtering, and ⁇ is further formed thereon. A film 23 made of tantalum was formed (see FIG. 3A).
  • step A a first process gas having an Ar flow rate of 10.0 sccm and a nitrogen gas flow rate of 30.0 sccm was introduced into the vacuum chamber 10 from the gas inlet 2 and maintained for 15 seconds in order to stabilize the gas flow rate of the vacuum chamber 10. .
  • step C the power of the plasma generating DC power source 9 is set to 18.0 kW, the power of the substrate bias high frequency power source 13 (1.0 to 13.56 MHz) is set to 600 W, and the same process gas as in step A is used. Sputtering was then performed for 3.0 seconds to form a base layer 22 (thickness: about 20 nm) made of TaN on the silicon wafer 21.
  • step B the first process gas was switched to the second process gas while maintaining the power of the plasma generating DC power supply 9 and the power of the substrate bias high frequency power supply 13 at the same conditions as in step C.
  • the second process gas had an Ar flow rate of 10.0 sccm and a nitrogen gas flow rate of 0.0 sccm. Switching to the second process gas, sputtering was performed for 15.0 seconds, and a film 23 (thickness: about 100 nm) made of ⁇ -tantalum was formed on the underlayer made of TaN.
  • the plasma generating DC power supply 9 and the substrate bias high frequency power supply 13 were turned off, the process gas was stopped, and the process gas was exhausted for 15.0 seconds.
  • step S101 a process gas having an Ar flow rate of 10.0 sccm and a nitrogen gas flow rate of 30.0 sccm was introduced into the vacuum chamber 10 from the gas inlet 2 and maintained for 15 seconds in order to stabilize the gas flow rate of the vacuum chamber 10.
  • step S102 the power of the plasma generating DC power source 9 is set to 18.0 kW
  • the power of the substrate bias high-frequency power source 13 (1.0 to 13.56 MHz) is set to 600 W
  • the same process gas as in step S101 is used.
  • sputtering was performed for 3.0 seconds, and a thin film layer 25 (thickness: about 20 nm) made of TaN was formed on the silicon wafer 24.
  • step S103 the process gas was switched to a process gas having an Ar flow rate of 10.0 sccm and a nitrogen gas flow rate of 0.0 sccm and maintained for 20 seconds, and nitrogen gas was removed from the vacuum chamber 10 to make the vacuum chamber 10 an Ar atmosphere.
  • step S104 the power of the plasma generating DC power source 9 and the power of the substrate bias high frequency power source 13 are set to the same conditions as in step S102, and the process gas is kept under the same conditions as in step S103 for 15.0 seconds of sputtering.
  • a film 26 (thickness: about 100 nm) made of ⁇ tantalum and ⁇ tantalum was formed on the underlayer 25 made of TaN.
  • the plasma generating DC power supply 9 and the substrate bias high frequency power supply 13 were turned off, the process gas was stopped, and the process gas was exhausted for 15.0 seconds.
  • step S201 a process gas having an Ar flow rate of 10.0 sccm and a nitrogen gas flow rate of 0.0 sccm was introduced into the vacuum chamber 10 from the gas inlet 2 and maintained for 15 seconds in order to stabilize the gas flow rate of the vacuum chamber 10.
  • step S202 the power of the DC power source 9 for generating plasma is set to 18.0 kW
  • the power of the substrate bias high frequency power source 13 (1.0 to 13.56 MHz) is set to 600 W
  • Sputtering was performed for 3.0 seconds, and a film (thickness: about 20 nm) made of ⁇ -tantalum was formed on the silicon wafer 27.
  • step S203 sputtering was further performed for 10.0 seconds under the same conditions as in step S202, and a film 28 (thickness: about 100 nm) made of ⁇ -tantalum was further formed.
  • the plasma generating DC power supply 9 and the substrate bias high frequency power supply 13 were turned off, the process gas was stopped, and the process gas was exhausted for 15.0 seconds.

Abstract

Disclosed is a method for forming a coating film that is composed of a-tantalum on a base using a sputtering method, which is characterized in that a coating film (23) that is composed of a-tantalum is formed on a base (21) by controlling plasma by introducing a first process gas that is composed of an inert gas and a nitrogen gas into a vacuum chamber, and introducing a second process gas that is composed of either an inert gas and/or a nitrogen gas into the vacuum chamber, after the introduction of the first process gas, so that the nitrogen partial pressure in the vacuum chamber is at a level at which a coating film that is composed of a-tantalum is formed.

Description

αタンタルからなる被膜の成膜方法、及びその被膜Method for forming film made of α-tantalum, and the film
　本発明は、αタンタルからなる被膜の成膜方法、及びその被膜に関する。
　本願は、２００９年７月２１日に、日本に出願された特願２００９－１７０５７７号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to a method for forming a film made of α-tantalum and the film.
This application claims priority based on Japanese Patent Application No. 2009-170577 filed in Japan on July 21, 2009, the contents of which are incorporated herein by reference.
　ＬＳＩやＩＣ等の半導体素子の配線では、基体と配線との間にバリアメタル層が設けられることによって、配線を構成する導電材料が基体の側へ拡散して起こる配線の劣化を防止することが行われる。
　前記バリアメタル層は、スパッタ等のＰＶＤ法や、気相成長法によって、金属又は金属化合物からなる薄膜を基体に成膜することによって形成される。 In wiring of semiconductor elements such as LSI and IC, a barrier metal layer is provided between the base and the wiring, thereby preventing deterioration of the wiring caused by diffusion of the conductive material constituting the wiring toward the base. Done.
The barrier metal layer is formed by forming a thin film made of a metal or a metal compound on a substrate by a PVD method such as sputtering or a vapor phase growth method.
　例えば、低誘電率（ｌｏｗ－ｋ）材料又は酸化シリコン（ＳｉＯ２）からなる基体に、窒化タンタル（ＴａＮ）、タンタル（Ｔａ）、及びそれらを組合わせた膜からなるバリアメタル層が形成された銅配線を有する半導体素子が開示されている（特許文献１）。 For example, a barrier metal layer made of tantalum nitride (TaN), tantalum (Ta), and a combination of them is formed on a base made of a low dielectric constant (low-k) material or silicon oxide (SiO 2 ). A semiconductor element having a copper wiring is disclosed (Patent Document 1).
特開２００３－１７９１３３号公報JP 2003-179133 A
　従来のバリアメタル層として用いられる薄膜のＴａは、比抵抗が高いという問題があった。
　これはタンタルの薄膜が、結晶系が立方晶であるタンタル（αタンタル）と結晶系が正方晶であるタンタル（βタンタル）とを含むためで、充分に比抵抗を低くすることが困難である。
　本発明に係る態様は、基体にαタンタルからなる被膜を成膜する方法を提供すること、及びその成膜方法によって形成されたαタンタルからなる被膜であって、前記基体から前記αタンタルからなる被膜方向に見て、前記αタンタルからなる被膜の前後の少なくともいずれか一方に、導体又は半導体が配されているαタンタルからなる被膜を提供することを目的とする。 A thin film Ta used as a conventional barrier metal layer has a problem of high specific resistance.
This is because the tantalum thin film contains tantalum (α tantalum) whose crystal system is cubic and tantalum (β tantalum) whose crystal system is tetragonal, and it is difficult to sufficiently reduce the specific resistance. .
An aspect according to the present invention provides a method of forming a film made of α-tantalum on a substrate, and a film made of α-tantalum formed by the film-forming method, which is made of the α-tantalum from the substrate. It is an object of the present invention to provide a film made of α-tantalum in which a conductor or a semiconductor is arranged on at least one of the front and rear sides of the film made of α-tantalum as viewed in the film direction.
　本発明に係る態様におけるαタンタルからなる被膜の成膜方法は、スパッタ法を用いて、αタンタルからなる被膜を基体に成膜する方法であって、不活性ガス及び窒素ガスからなる第１のプロセスガスを真空槽に導入し、前記第１のプロセスガス導入の後、αタンタルからなる被膜が形成される窒素分圧となるように、不活性ガス及び窒素ガスのうち少なくとも一つからなる第２のプロセスガスを前記真空槽に導入してプラズマを制御することにより、αタンタルからなる被膜を基体に形成することを特徴とする。
　上記αタンタルからなる被膜の成膜方法は、前記第１のプロセスガス導入の後、窒化タンタルからなる下地層を基体に形成し、前記窒化タンタルからなる下地層を前記基体に形成した後、前記αタンタルからなる被膜を前記基体に形成することを特徴とする。
　上記αタンタルからなる被膜の成膜方法は、前記基体の材料として、シリコンを用いることを特徴とする。
　上記αタンタルからなる被膜の成膜方法は、前記基体の材料として、酸化シリコン或いは石英を用いることを特徴とする。 The film forming method of α tantalum according to the aspect of the present invention is a method of forming a film of α tantalum on a substrate by using a sputtering method, and is a first method including an inert gas and a nitrogen gas. A process gas is introduced into the vacuum chamber, and after the introduction of the first process gas, a first gas comprising at least one of an inert gas and a nitrogen gas is formed so as to have a nitrogen partial pressure at which a film made of α-tantalum is formed. A film made of α-tantalum is formed on the substrate by introducing the process gas 2 into the vacuum chamber and controlling the plasma.
In the film formation method of the α-tantalum, after the first process gas is introduced, an underlayer made of tantalum nitride is formed on the substrate, and an underlayer made of tantalum nitride is formed on the substrate, A film made of α-tantalum is formed on the substrate.
The method for forming a film made of α-tantalum is characterized in that silicon is used as the base material.
The method for forming a film made of α-tantalum is characterized in that silicon oxide or quartz is used as the substrate material.
本発明に係る態様におけるαタンタルからなる被膜は、上記成膜方法によって形成されたαタンタルからなる被膜であって、前記基体から前記αタンタルからなる被膜に向かう方向において、前記αタンタルからなる被膜の前位置及び後位置の少なくともいずれか一方に、導体又は半導体が配されていることを特徴とする。 The film made of α tantalum in the aspect according to the present invention is a film made of α tantalum formed by the film forming method, and the film made of α tantalum in the direction from the substrate toward the film made of α tantalum. A conductor or a semiconductor is disposed at at least one of the front position and the rear position.
　本発明に係る態様におけるαタンタルからなる被膜の成膜方法によれば、従来困難であったαタンタルからなる被膜を基体に形成することが容易にできる。
　本発明に係る態様におけるαタンタルからなる被膜は、基体からそのαタンタルからなる被膜を見て、αタンタルからなる被膜の前後の少なくとも一方に導体又は半導体が配されており、比抵抗の低いバリアメタル膜として前記導体又は半導体の材料が基体に拡散することを防ぎ、且つ前記導体又は半導体の基体への密着性を高めることができる。 According to the film formation method of α tantalum according to the aspect of the present invention, it is possible to easily form a film of α tantalum, which has been difficult in the past, on the substrate.
The coating made of α tantalum according to the embodiment of the present invention is a barrier having a low specific resistance, in which a conductor or semiconductor is disposed on at least one of the coating made of α tantalum when the coating made of α tantalum is viewed from the substrate. As a metal film, the conductor or semiconductor material can be prevented from diffusing into the substrate, and the adhesion of the conductor or semiconductor to the substrate can be enhanced.
本発明に係る態様におけるαタンタルからなる被膜の成膜方法に用いることのできるスパッタリング装置の一例。An example of the sputtering apparatus which can be used for the film-forming method of the film which consists of alpha tantalum in the aspect which concerns on this invention. 窒素ガス流量と形成されたＴａ薄膜の比抵抗の関係を示す図。The figure which shows the relationship between the nitrogen gas flow rate and the specific resistance of the formed Ta thin film. 本発明に係る態様におけるαタンタルからなる被膜の成膜方法によって基体に成膜されたαタンタルからなる被膜の断面図。Sectional drawing of the film which consists of (alpha) tantalum formed into a film | membrane by the film-forming method of the film which consists of (alpha) tantalum in the aspect which concerns on this invention. 図３Ａに示すαタンタルからなる被膜のＸ線回折スペクトル。FIG. 3A is an X-ray diffraction spectrum of a film made of α-tantalum shown in FIG. 3A. 基体に成膜されたβタンタル及びαタンタルからなる被膜の断面図。Sectional drawing of the film which consists of (beta) tantalum and (alpha) tantalum formed into a film on the base | substrate. 図４Ａに示すβタンタル及びαタンタルからなる被膜のＸ線回折スペクトル。FIG. 4A is an X-ray diffraction spectrum of a film made of β-tantalum and α-tantalum shown in FIG. 4A. 基体に成膜されたβタンタルからなる被膜の断面図。Sectional drawing of the film which consists of (beta) tantalum formed into a film on the base | substrate. 図５Ａに示すβタンタルからなる被膜のＸ線回折スペクトル。The X-ray-diffraction spectrum of the film which consists of (beta) tantalum shown to FIG. 5A.
　以下、好適な実施の形態に基づき、図面を参照して本発明に係る態様を説明する。
　本実施形態のαタンタルからなる被膜の成膜方法は、スパッタ法を用いて、αタンタルからなる被膜を基体に成膜する方法であって、不活性ガス及び窒素ガスからなる第１のプロセスガスを導入する工程Ａと、αタンタルからなる被膜が形成される窒素分圧となるように、不活性ガス及び／又は窒素ガスからなる第２のプロセスガスを設定してプラズマを制御することにより、αタンタルからなる被膜を基体に形成する工程Ｂとを順に備える。 Hereinafter, based on preferred embodiments, aspects according to the present invention will be described with reference to the drawings.
The film formation method of α tantalum according to the present embodiment is a method of forming a film of α tantalum on a substrate using a sputtering method, and is a first process gas including an inert gas and a nitrogen gas. By controlling the plasma by setting a second process gas consisting of an inert gas and / or nitrogen gas so as to achieve a nitrogen partial pressure at which a film made of α-tantalum is formed and step A introducing α Step B for forming a coating made of α-tantalum on the substrate.
　前記スパッタ法としては、金属薄膜を基板上に成膜することができる一般のスパッタ法が適用可能であり、例えば、マグネトロンスパッタ、反応性スパッタ等のスパッタ法が挙げられる。 As the sputtering method, a general sputtering method capable of forming a metal thin film on a substrate can be applied, and examples thereof include sputtering methods such as magnetron sputtering and reactive sputtering.
　前記スパッタ法におけるターゲットとしては、Ｔａからなるターゲット（以下、Ｔａターゲットという。）が用いられる。
　前記スパッタ法における圧力としては、公知のスパッタ法で用いられる圧力で行うことができ、例えば１．０×１０－６Ｐａ以上４００Ｐａ以下で行うことができる。
　前記スパッタ法における基体温度としては、公知のスパッタ法で用いられる温度で行うことができ、例えば－５０℃以上６００℃以下で行うことができる。 As a target in the sputtering method, a target made of Ta (hereinafter referred to as Ta target) is used.
The pressure in the sputtering method can be a pressure used in a known sputtering method, for example, 1.0 × 10 −6 Pa or more and 400 Pa or less.
The substrate temperature in the sputtering method may be a temperature used in a known sputtering method, and may be, for example, from −50 ° C. to 600 ° C.
　前記基体としては、スパッタ法による成膜時の温度に耐えうる材料からなるものであれば特に制限されず、例えばシリコンからなる基板、酸化シリコンからなる基板、石英からなる基板、金属からなる基板等が挙げられる。また、前記基体としては、前記基板に予め下地層として他の薄膜等が成膜されたものであってもよい。 The substrate is not particularly limited as long as it is made of a material that can withstand the temperature at the time of film formation by sputtering. For example, a substrate made of silicon, a substrate made of silicon oxide, a substrate made of quartz, a substrate made of metal, etc. Is mentioned. In addition, the substrate may be one in which another thin film or the like is previously formed as a base layer on the substrate.
　前記不活性ガスとしては、スパッタ法に用いられる不活性ガスであれば特に制限されず、例えばアルゴン（Ａｒ）、クリプトン（Ｋｒ）、ヘリウム（Ｈｅ）等が挙げられる。なかでも、一般に入手が容易で安価なＡｒがより好ましい。
　前記窒素ガス（Ｎ２）は、一般にスパッタ法で用いられる純度の窒素ガスであればよく、高純度であるほどよい。 The inert gas is not particularly limited as long as it is an inert gas used for sputtering, and examples thereof include argon (Ar), krypton (Kr), helium (He), and the like. Of these, Ar, which is generally easily available and inexpensive, is more preferable.
The nitrogen gas (N 2 ) may be a nitrogen gas having a purity generally used in sputtering, and the higher the purity, the better.
　本実施形態のαタンタルからなる被膜の成膜方法によれば、従来困難であったαタンタルからなる被膜を基体に成膜することができる。
　従来のスパッタ法によるタンタルからなる薄膜の成膜方法では、Ａｒ等の不活性ガス雰囲気下でＴａターゲットを用いてスパッタリングすることによりタンタルからなる薄膜を成膜していたが、形成されるのはβタンタル及びαタンタルからなる薄膜であった。
　一方、本実施形態では、Ｔａターゲットを用いてスパッタリングする際に、下記工程Ａと下記工程Ｂを順に行うことによって、αタンタルからなる被膜を基体に成膜することが可能である。
　以下に、本実施形態のαタンタルからなる被膜の成膜方法を、第一態様と第二態様とによって説明する。 According to the film formation method of α tantalum according to the present embodiment, it is possible to form a film of α tantalum on the substrate, which has been difficult in the past.
In the conventional method for forming a thin film made of tantalum by sputtering, a thin film made of tantalum was formed by sputtering using a Ta target in an inert gas atmosphere such as Ar. It was a thin film made of β-tantalum and α-tantalum.
On the other hand, in the present embodiment, when sputtering is performed using a Ta target, a film made of α-tantalum can be formed on the substrate by performing the following step A and the following step B in order.
Below, the film-forming method of the film which consists of alpha tantalum of this embodiment is demonstrated by the 1st aspect and the 2nd aspect.
＜第一態様＞
　本実施形態のαタンタルからなる被膜の成膜方法の第一態様を、図１に示したスパッタ装置１を参照して説明する。 <First aspect>
A first aspect of the film forming method of α-tantalum according to the present embodiment will be described with reference to the sputtering apparatus 1 shown in FIG.
　真空槽１０の天井には、カソード電極４が固定されており、その表面にはＴａターゲット５が配置されている。カソード電極４には負電圧を印加する直流電源９が接続されている。
　真空槽１０外のカソード電極４の裏面位置には、永久磁石からなる磁気回路８が設けられており、その磁気回路８が形成する磁束がカソード電極４とＴａターゲット５を貫通し、Ｔａターゲット５表面に漏洩磁界が形成されるように構成されている。スパッタリングを行う際にはその漏洩磁界に電子がトラップされ、プラズマが高密度化する。 A cathode electrode 4 is fixed to the ceiling of the vacuum chamber 10, and a Ta target 5 is disposed on the surface thereof. A DC power supply 9 for applying a negative voltage is connected to the cathode electrode 4.
A magnetic circuit 8 made of a permanent magnet is provided at the back surface position of the cathode electrode 4 outside the vacuum chamber 10, and the magnetic flux formed by the magnetic circuit 8 penetrates the cathode electrode 4 and the Ta target 5, and the Ta target 5 A leakage magnetic field is formed on the surface. When sputtering is performed, electrons are trapped in the leakage magnetic field, and the plasma is densified.
　真空槽１０の底面には、基体電極６が設けられており、その表面には基体７がＴａターゲット５と略平行に対向配置されている。
　基体電極６は高周波バイアス電力を印加する高周波電源１３に接続されている。また、基体電極６には絶縁部１１ａによって電気的に絶縁されたヒーター１１が設けられており、基体７の温度を－５０℃～６００℃に調節することができる。 A substrate electrode 6 is provided on the bottom surface of the vacuum chamber 10, and a substrate 7 is disposed on the surface of the substrate electrode 6 so as to face the Ta target 5 substantially in parallel.
The substrate electrode 6 is connected to a high frequency power source 13 for applying a high frequency bias power. Further, the base electrode 6 is provided with a heater 11 electrically insulated by an insulating portion 11a, and the temperature of the base 7 can be adjusted to −50 ° C. to 600 ° C.
　真空槽１０にはガス導入口２と真空排気口３とが設けられている。ガス導入口２にはプロセスガスを構成するＡｒ及び窒素ガスのガスボンベが、それぞれの流量を個別に調節できるように接続されている。真空排気口３には、真空ポンプが接続されている（ガスボンベ及び真空ポンプは図示しない。）。 The vacuum chamber 10 is provided with a gas inlet 2 and a vacuum exhaust 3. A gas cylinder of Ar and nitrogen gas constituting the process gas is connected to the gas inlet 2 so that the respective flow rates can be adjusted individually. A vacuum pump is connected to the vacuum exhaust port 3 (a gas cylinder and a vacuum pump are not shown).
　本実施形態における前記工程Ａは、不活性ガス及び窒素ガスからなる第１のプロセスガスを真空槽１０に導入する工程である。
　ガス導入口２から真空槽１０に導入される前記第１のプロセスガスの流量は、不活性ガスの流量と窒素ガスの流量との和である。
　前記第１のプロセスガスにおける不活性ガスの流量としては特に制限されず、例えば１．０ｓｃｃｍ以上３０ｓｃｃｍ以下でおこなうことができる。
　前記第１のプロセスガスにおける窒素ガスの流量としては特に制限されず、例えば０．０１ｓｃｃｍ以上３０ｓｃｃｍ以下で行うことができる。
　なお、前記ｓｃｃｍは、ｃｍ３／分（１ａｔｍ，０℃）で表される単位である。
　このように工程Ａで予め前記第１のプロセスガスを導入することにより、真空槽１０内のガス流量及び圧力を安定させることができ、さらに、後述の工程Ｂでαタンタルからなる被膜をスパッタ法によって形成する際のプラズマ発生を安定させることができる。 The step A in the present embodiment is a step of introducing a first process gas composed of an inert gas and a nitrogen gas into the vacuum chamber 10.
The flow rate of the first process gas introduced into the vacuum chamber 10 from the gas inlet 2 is the sum of the flow rate of the inert gas and the flow rate of the nitrogen gas.
The flow rate of the inert gas in the first process gas is not particularly limited and can be, for example, 1.0 sccm or more and 30 sccm or less.
The flow rate of the nitrogen gas in the first process gas is not particularly limited and can be, for example, 0.01 sccm or more and 30 sccm or less.
The sccm is a unit expressed in cm 3 / min (1 atm, 0 ° C.).
In this way, by introducing the first process gas in advance in step A, the gas flow rate and pressure in the vacuum chamber 10 can be stabilized, and a film made of α-tantalum is sputtered in step B described later. The generation of plasma during formation can be stabilized.
　前記工程Ａで前記第１のプロセスガスが導入された真空槽１０内の圧力としては、スパッタ法に適した圧力範囲１．０×１０－６Ｐａ以上４００Ｐａ以下が好ましく、より好ましくは０．００１Ｐａ以上１０Ｐａ以下であり、さらに好ましくは０．０１Ｐａ以上１．０Ｐａ以下である。
　上記範囲の圧力であると、後述の工程Ｂにおいて、αタンタルからなる被膜を基体に効率よく成膜することができる。 The pressure in the vacuum chamber 10 into which the first process gas is introduced in the step A is preferably a pressure range suitable for the sputtering method of 1.0 × 10 −6 Pa to 400 Pa, more preferably 0.001 Pa. It is 10 Pa or less, More preferably, it is 0.01 Pa or more and 1.0 Pa or less.
When the pressure is in the above range, a film made of α-tantalum can be efficiently formed on the substrate in Step B described later.
　本実施形態における前記工程Ｂは、αタンタルからなる被膜が形成される窒素分圧となるように、不活性ガス及び／又は窒素ガスからなる第２のプロセスガスを設定してプラズマを制御することにより、αタンタルからなる被膜を基体に形成する工程である。
　前記工程Ｂでは、前記工程Ａで導入した前記第１のプロセスガスの雰囲気下にある真空槽１０に前記第２のプロセスガスを入れて、真空槽１０における窒素分圧をαタンタルからなる被膜の形成に適したものとする。 In the step B in the present embodiment, the plasma is controlled by setting a second process gas made of an inert gas and / or a nitrogen gas so as to have a nitrogen partial pressure at which a film made of α-tantalum is formed. Is a step of forming a film of α-tantalum on the substrate.
In the step B, the second process gas is put into the vacuum chamber 10 under the atmosphere of the first process gas introduced in the step A, and the partial pressure of nitrogen in the vacuum chamber 10 is changed to that of α tantalum. It shall be suitable for formation.
　ガス導入口２から真空槽１０に導入される前記第２のプロセスガスの流量は、不活性ガスの流量と窒素ガスの流量との和である。
　前記第２のプロセスガスのうち、不活性ガスの流量としては、５．０ｓｃｃｍ以上２０ｓｃｃｍ以下が好ましく、５．０ｓｃｃｍ以上１５ｓｃｃｍ以下がより好ましく、８．０ｓｃｃｍ以上１２ｓｃｃｍ以下がさらに好ましい。
　前記第２のプロセスガスのうち、窒素ガスの流量としては、０．０１ｓｃｃｍ以上５．０ｓｃｃｍ以下が好ましく、０．０５ｓｃｃｍ以上２．５ｓｃｃｍ以下がより好ましく、０．１ｓｃｃｍ以上１．０ｓｃｃｍ以下がさらに好ましい。
　なお、前記ｓｃｃｍは、ｃｍ３／分（１ａｔｍ，０℃）で表される単位である。
　真空槽１０に導入される前記第２のプロセスガスの不活性ガスと窒素ガスとの流量比（不活性ガスの流量：窒素ガスの流量）としては、２０００：１～１：１が好ましく、３００：１～２：１がより好ましく、１２０：１～８：１がさらに好ましい。ここで上記範囲は、その両端の流量比を含むものである。
　前記第２のプロセスガスを構成するＡｒ及び窒素ガスを上記流量の範囲で設定することにより、真空槽１０内をαタンタルからなる被膜が形成される窒素分圧とすることができる。この第２のプロセスガスが設定された真空槽１０の不活性ガス及び窒素ガスのそれぞれの分圧の好ましい範囲は下記のとおりである。 The flow rate of the second process gas introduced into the vacuum chamber 10 from the gas inlet 2 is the sum of the flow rate of the inert gas and the flow rate of the nitrogen gas.
Of the second process gas, the flow rate of the inert gas is preferably 5.0 sccm or more and 20 sccm or less, more preferably 5.0 sccm or more and 15 sccm or less, and further preferably 8.0 sccm or more and 12 sccm or less.
Of the second process gas, the flow rate of nitrogen gas is preferably 0.01 sccm or more and 5.0 sccm or less, more preferably 0.05 sccm or more and 2.5 sccm or less, and further preferably 0.1 sccm or more and 1.0 sccm or less. .
The sccm is a unit expressed in cm 3 / min (1 atm, 0 ° C.).
The flow rate ratio between the inert gas of the second process gas and the nitrogen gas introduced into the vacuum chamber 10 (the flow rate of the inert gas: the flow rate of the nitrogen gas) is preferably 2000: 1 to 1: 1, : 1 to 2: 1 is more preferable, and 120: 1 to 8: 1 is more preferable. Here, the above range includes the flow ratio at both ends.
By setting the Ar and nitrogen gas constituting the second process gas within the above flow rate range, the inside of the vacuum chamber 10 can be set to a nitrogen partial pressure at which a film made of α-tantalum is formed. The preferable ranges of the partial pressures of the inert gas and the nitrogen gas in the vacuum chamber 10 in which the second process gas is set are as follows.
　前記第２のプロセスガスが設定された真空槽１０における不活性ガスの分圧としては、０．０３Ｐａ以上５．０Ｐａ以下が好ましく、０．０３Ｐａ以上１．０Ｐａ以下がより好ましく、０．０３Ｐａ以上０．５Ｐａ以下がさらに好ましい。
　前記第２のプロセスガスが設定された真空槽１０における窒素分圧（窒素ガス分圧）としては、０．００１Ｐａ以上０．０２Ｐａ以下が好ましく、０．００１Ｐａ以上０．０１Ｐａ以下がより好ましく、０．００３Ｐａ以上０．００７Ｐａ以下がさらに好ましい。 The partial pressure of the inert gas in the vacuum chamber 10 in which the second process gas is set is preferably 0.03 Pa or more and 5.0 Pa or less, more preferably 0.03 Pa or more and 1.0 Pa or less, and more preferably 0.03 Pa or more. 0.5 Pa or less is more preferable.
The nitrogen partial pressure (nitrogen gas partial pressure) in the vacuum chamber 10 in which the second process gas is set is preferably 0.001 Pa or more and 0.02 Pa or less, more preferably 0.001 Pa or more and 0.01 Pa or less, and 0 More preferably 0.003 Pa or more and 0.007 Pa or less.
　前記αタンタルからなる被膜が形成される窒素分圧で真空槽１０内が安定したところで、直流電源９を起動し、カソード電極４に負電圧を印加して放電を開始して、Ｔａターゲット５表面にプラズマを発生することによって、スパッタリングすることができる。このとき、基体電極６には高周波電源１３によって高周波バイアスを印加してもよい。 When the inside of the vacuum chamber 10 is stabilized at the nitrogen partial pressure at which the α tantalum film is formed, the DC power source 9 is started, a negative voltage is applied to the cathode electrode 4 to start discharging, and the surface of the Ta target 5 Sputtering can be performed by generating plasma. At this time, a high frequency bias may be applied to the base electrode 6 by a high frequency power source 13.
　直流電源９の電力としては、本実施形態の効果が優れることから、５．０ｋＷ以上３０ｋＷ以下が好ましく、１０ｋＷ以上２５ｋＷ以下がより好ましく、１５ｋＷ以上２０ｋＷ以下が最も好ましい。
　高周波電源１３を印加する場合、その周波数としては、本実施形態の効果が優れることから、１．０ＭＨｚ以上１３．５６ＭＨｚ以下が好ましい。 The power of the DC power supply 9 is preferably 5.0 kW or more and 30 kW or less, more preferably 10 kW or more and 25 kW or less, and most preferably 15 kW or more and 20 kW or less because the effect of the present embodiment is excellent.
When the high frequency power supply 13 is applied, the frequency is preferably 1.0 MHz to 13.56 MHz because the effect of the present embodiment is excellent.
　このようにスパッタリングすることにより、基体７にαタンタルからなる被膜を成膜することができる。
　成膜されるαタンタルからなる被膜の厚さは、スパッタリング時間を適宜調整することによって所望の厚さにすることができ、例えば１ｎｍ以上２００μｍ以下の厚さで成膜することができる。 By sputtering in this way, a film made of α-tantalum can be formed on the substrate 7.
The thickness of the film made of α-tantalum to be formed can be set to a desired thickness by appropriately adjusting the sputtering time. For example, the film can be formed with a thickness of 1 nm to 200 μm.
　前記αタンタルからなる被膜が成膜される基体７の面としては特に制限されず、例えば、シリコンからなる基板の表面であってもよいし、酸化シリコンからなる基板の表面であってもよいし、それらの基板にＴａＮ等からなる薄膜等が予め下地層として形成された面であってもよい。 The surface of the substrate 7 on which the α-tantalum film is formed is not particularly limited, and may be, for example, the surface of a substrate made of silicon or the surface of a substrate made of silicon oxide. Further, a surface on which a thin film made of TaN or the like is previously formed as a base layer may be used.
＜第二態様＞
　本実施形態のαタンタルからなる被膜の成膜方法の第二態様を、図１に示したスパッタ装置１を参照して説明する。
　スパッタ装置１の構成は、第一態様で説明したスパッタ装置１の構成と同様である。 <Second aspect>
A second mode of the film forming method of α-tantalum according to this embodiment will be described with reference to the sputtering apparatus 1 shown in FIG.
The configuration of the sputtering apparatus 1 is the same as the configuration of the sputtering apparatus 1 described in the first aspect.
　本実施形態における前記工程Ａは、不活性ガス及び窒素ガスからなる第１のプロセスガスを真空槽１０に導入する工程である。
　ガス導入口２から真空槽１０に導入される前記第１のプロセスガスの流量は、不活性ガスの流量と窒素ガスの流量との和である。
　前記第１のプロセスガスにおける不活性ガスの流量としては、５．０ｓｃｃｍ以上２０ｓｃｃｍ以下が好ましく、５．０ｓｃｃｍ以上１５ｓｃｃｍ以下がより好ましく、８．０ｓｃｃｍ以上１２ｓｃｃｍ以下が最も好ましい。
　前記第１のプロセスガスにおける窒素ガスの流量としては、１５ｓｃｃｍ以上６０ｓｃｃｍ以下が好ましく、２０ｓｃｃｍ以上４０ｓｃｃｍ以下がより好ましく、２５ｓｃｃｍ以上３５ｓｃｃｍ以下が最も好ましい。
　なお、前記ｓｃｃｍは、ｃｍ３／分（１ａｔｍ，０℃）で表される単位である。 The step A in the present embodiment is a step of introducing a first process gas composed of an inert gas and a nitrogen gas into the vacuum chamber 10.
The flow rate of the first process gas introduced into the vacuum chamber 10 from the gas inlet 2 is the sum of the flow rate of the inert gas and the flow rate of the nitrogen gas.
The flow rate of the inert gas in the first process gas is preferably 5.0 sccm or more and 20 sccm or less, more preferably 5.0 sccm or more and 15 sccm or less, and most preferably 8.0 sccm or more and 12 sccm or less.
The flow rate of nitrogen gas in the first process gas is preferably 15 sccm or more and 60 sccm or less, more preferably 20 sccm or more and 40 sccm or less, and most preferably 25 sccm or more and 35 sccm or less.
The sccm is a unit expressed in cm 3 / min (1 atm, 0 ° C.).
　真空槽１０に導入される前記第１のプロセスガスの不活性ガスと窒素ガスとの流量比（不活性ガスの流量：窒素ガスの流量）としては、１：２～１：５が好ましく、１：２～１：４がより好ましく、１：２．５～１：３．５が最も好ましい。ここで上記範囲は、その両端の流量比を含むものである。 The flow rate ratio between the inert gas and nitrogen gas of the first process gas introduced into the vacuum chamber 10 (inert gas flow rate: nitrogen gas flow rate) is preferably 1: 2 to 1: 5. : 2 to 1: 4 is more preferable, and 1: 2.5 to 1: 3.5 is most preferable. Here, the above range includes the flow ratio at both ends.
　前記工程Ａで前記第１のプロセスガスが導入された真空槽１０内の圧力としては、前述のように１．０×１０－６Ｐａ以上４００Ｐａ以下で行うことができるが、より好ましくは０．０１Ｐａ以上１０Ｐａ以下であり、さらに好ましくは０．１Ｐａ以上１．０Ｐａ以下である。 As described above, the pressure in the vacuum chamber 10 into which the first process gas has been introduced in the step A can be 1.0 × 10 −6 Pa or more and 400 Pa or less, and more preferably, 0.1. It is 01 Pa or more and 10 Pa or less, More preferably, it is 0.1 Pa or more and 1.0 Pa or less.
　また、前記工程Ａで前記第１のプロセスガスが導入された真空槽１０の窒素分圧としては、公知のＴａＮからなる薄膜をスパッタ法で形成する際の窒素分圧であることが好ましく、例えば、０．０３Ｐａ以上５．０Ｐａ以下が好ましく、０．０３Ｐａ以上１．０Ｐａ以下がより好ましく、０．０３Ｐａ以上０．５Ｐａ以下がさらに好ましい。
　上記範囲の窒素分圧において、スパッタリングした場合、ＴａＮからなる下地層を基体７に形成することができる。
　そのスパッタリングの方法としては、直流電源９を起動し、カソード電極４に負電圧を印加して放電を開始して、Ｔａターゲット５表面にプラズマを発生することによって、スパッタリングすることができる。このとき、基体電極６には高周波電源１３によって高周波バイアスを印加してもよい。 Further, the nitrogen partial pressure of the vacuum chamber 10 into which the first process gas is introduced in the step A is preferably a nitrogen partial pressure when a thin film made of known TaN is formed by a sputtering method. 0.03 Pa to 5.0 Pa, preferably 0.03 Pa to 1.0 Pa, and more preferably 0.03 Pa to 0.5 Pa.
When sputtering is performed at a nitrogen partial pressure in the above range, a base layer made of TaN can be formed on the substrate 7.
As the sputtering method, sputtering can be performed by starting the DC power supply 9, applying a negative voltage to the cathode electrode 4 to start discharge, and generating plasma on the surface of the Ta target 5. At this time, a high frequency bias may be applied to the base electrode 6 by a high frequency power source 13.
　本実施形態における前記工程Ｂは、αタンタルからなる被膜が形成される窒素分圧となるように、不活性ガス及び／又は窒素ガスからなる第２のプロセスガスを設定してプラズマを制御することにより、αタンタルからなる被膜を基体７に形成する工程である。
　前記工程Ｂでは、前記工程Ａで導入した第１のプロセスガス雰囲気下にある真空槽１０に第２のプロセスガスとして不活性ガスのみを入れて、真空槽１０における窒素分圧を連続的に下げつつ、前述のようにスパッタリングすることによって、基体７にαタンタルからなる被膜を成膜することができる。 In the step B in the present embodiment, the plasma is controlled by setting a second process gas made of an inert gas and / or a nitrogen gas so as to have a nitrogen partial pressure at which a film made of α-tantalum is formed. In this step, a film made of α-tantalum is formed on the substrate 7.
In the step B, only the inert gas is put as the second process gas in the vacuum chamber 10 under the first process gas atmosphere introduced in the step A, and the nitrogen partial pressure in the vacuum chamber 10 is continuously lowered. On the other hand, a film made of α-tantalum can be formed on the substrate 7 by sputtering as described above.
　前記工程Ｂにおいて、真空槽１０の窒素分圧を連続的に下げる方法は、第２のプロセスガスを設定する際に、窒素ガスの流入を停止して、不活性ガスのみを流入することで行うことができる。真空槽１０では、流入するガスと同量のガスを排気して真空槽１０の圧力を一定に保っているので、不活性ガスのみの流入に切り替えることによって、真空槽１０に残存する窒素ガスの濃度を連続的に下げることができる。したがって、不活性ガスのみの流入を継続した場合、真空槽１０の窒素分圧は最後には実質０となる。 In the step B, the method of continuously lowering the nitrogen partial pressure in the vacuum chamber 10 is performed by stopping the inflow of nitrogen gas and flowing in only the inert gas when setting the second process gas. be able to. In the vacuum chamber 10, the same amount of gas as the inflowing gas is exhausted to keep the pressure of the vacuum chamber 10 constant. Therefore, by switching to the inflow of only the inert gas, the nitrogen gas remaining in the vacuum chamber 10 is changed. The concentration can be lowered continuously. Therefore, when the inflow of only the inert gas is continued, the nitrogen partial pressure in the vacuum chamber 10 finally becomes substantially zero.
　このように真空槽１０の窒素分圧を連続的に下げて実質０とする過程で、αタンタルからなる被膜が基体７に形成される窒素分圧を通過する。
　すなわち、真空槽１０の窒素分圧がＴａＮ膜の形成されうる窒素分圧であるときにスパッタリングを開始して基体７にＴａＮの下地層を形成しながら、その窒素分圧を前述のように連続的に下げつつスパッタリングを継続することによって、αタンタルからなる被膜が基体７に形成される窒素分圧に達したときに、基体７にはαタンタルからなる被膜が形成され始める。その後、さらに窒素分圧を下げつつスパッタリングを継続することによって、先に形成されたαタンタルからなる被膜の上にαタンタルからなる被膜が形成される。その窒素分圧は最後には実質０になるが、その場合でもスパッタリングを継続することによって、αタンタルからなる被膜の形成が継続される。 Thus, in the process of continuously lowering the nitrogen partial pressure in the vacuum chamber 10 to substantially zero, the coating made of α-tantalum passes through the nitrogen partial pressure formed on the substrate 7.
That is, when the nitrogen partial pressure in the vacuum chamber 10 is a nitrogen partial pressure at which a TaN film can be formed, sputtering is started to form a TaN underlayer on the substrate 7, and the nitrogen partial pressure is continuously maintained as described above. By continuing the sputtering while lowering, the film of α tantalum starts to be formed on the substrate 7 when the film of α tantalum reaches the nitrogen partial pressure formed on the substrate 7. Thereafter, sputtering is continued while further reducing the nitrogen partial pressure, whereby a film made of α-tantalum is formed on the previously formed film made of α-tantalum. The nitrogen partial pressure finally becomes substantially zero, but even in this case, the formation of the film made of α-tantalum is continued by continuing the sputtering.
 上述のように、一端基体７にαタンタルが形成されると、その後に積層するタンタルは全てαタンタルとなるメカニズムは、仮説として、先に形成されたαタンタルからなる被膜が結晶成長における核として機能し、その後に積層されるタンタルがαタンタルとなって成膜されることが考えられる。 As described above, when α tantalum is formed on the substrate 7 at one end, the mechanism that all tantalum laminated thereafter becomes α tantalum is hypothesized that the previously formed coating of α tantalum serves as the nucleus for crystal growth. It is conceivable that the tantalum that functions and is subsequently laminated becomes α-tantalum.
　成膜されるαタンタルからなる被膜の厚さは、スパッタリング時間を適宜調整することによって所望の厚さにすることができ、例えば１ｎｍ以上２００μｍ以下の厚さで成膜することができる。 The thickness of the film made of α-tantalum to be formed can be set to a desired thickness by appropriately adjusting the sputtering time. For example, the film can be formed with a thickness of 1 nm to 200 μm.
　前記工程Ｂで前記第２のプロセスガスが設定された真空槽１０内の圧力としては、スパッタ法に適した圧力範囲１．０×１０－６Ｐａ以上４００Ｐａ以下が好ましく、より好ましくは０．００１Ｐａ以上１０Ｐａ以下であり、さらに好ましくは０．０１Ｐａ以上１．０Ｐａ以下である。 The pressure in the vacuum chamber 10 in which the second process gas is set in the step B is preferably a pressure range suitable for the sputtering method of 1.0 × 10 −6 Pa to 400 Pa, more preferably 0.001 Pa. It is 10 Pa or less, More preferably, it is 0.01 Pa or more and 1.0 Pa or less.
　ガス導入口２から真空槽１０に流入される前記第２のプロセスガスの流量は、不活性ガスの流量と窒素ガスの流量との和である。
　前記第２のプロセスガスのうち、不活性ガスの流量としては、５．０ｓｃｃｍ以上２０ｓｃｃｍ以下が好ましく、５．０ｓｃｃｍ以上１５ｓｃｃｍ以下がより好ましく、８．０ｓｃｃｍ以上１２ｓｃｃｍ以下がさらに好ましい。
　前記第２のプロセスガスのうち、窒素ガスの流量としては、０ｓｃｃｍ以上０．５ｓｃｃｍ以下が好ましく、０ｓｃｃｍ以上０．２５ｓｃｃｍ以下がより好ましく、０ｓｃｃｍが最も好ましい。
　なお、前記ｓｃｃｍは、ｃｍ３／分（１ａｔｍ，０℃）で表される単位である。 The flow rate of the second process gas that flows into the vacuum chamber 10 from the gas inlet 2 is the sum of the flow rate of the inert gas and the flow rate of the nitrogen gas.
Of the second process gas, the flow rate of the inert gas is preferably 5.0 sccm or more and 20 sccm or less, more preferably 5.0 sccm or more and 15 sccm or less, and further preferably 8.0 sccm or more and 12 sccm or less.
Of the second process gas, the flow rate of nitrogen gas is preferably 0 sccm or more and 0.5 sccm or less, more preferably 0 sccm or more and 0.25 sccm or less, and most preferably 0 sccm.
The sccm is a unit expressed in cm 3 / min (1 atm, 0 ° C.).
　前記スパッタリングにおいて、直流電源９の電力としては、本実施形態の効果が優れることから、５．０ｋＷ以上３０ｋＷ以下が好ましく、１０ｋＷ以上２５ｋＷ以下がより好ましく、１５ｋＷ以上２０ｋＷ以下が最も好ましい。
　前記スパッタリングにおいて、高周波電源１３を印加する場合、その周波数としては、本実施形態の効果が優れることから、１．０ＭＨｚ以上１３．５６ＭＨｚ以下が好ましい。 In the sputtering, the power of the DC power source 9 is preferably 5.0 kW or more and 30 kW or less, more preferably 10 kW or more and 25 kW or less, and most preferably 15 kW or more and 20 kW or less because the effect of the present embodiment is excellent.
In the sputtering, when the high frequency power supply 13 is applied, the frequency is preferably 1.0 MHz or more and 13.56 MHz or less because the effect of the present embodiment is excellent.
　このようにスパッタリングすることにより、基体７にＴａＮからなる下地層を形成し、さらにその上にαタンタルからなる被膜を成膜することができる。
　前記ＴａＮからなる下地層を基体７に形成しない場合は、真空槽１０内の窒素分圧がαタンタルからなる被膜が形成される窒素分圧となるまで、基体７をシャッター等で覆って、ＴａＮからなる下地層が基体７に形成されることを防げばよい。
　前記αタンタルからなる被膜が成膜される基体７の面としては特に制限されず、例えば、シリコンからなる基板の表面であってもよいし、酸化シリコンからなる基板の表面であってもよいし、それらの基板にＴａＮ等からなる薄膜等が予め下地層として形成された面であってもよい。 By sputtering in this way, a base layer made of TaN can be formed on the substrate 7, and a film made of α-tantalum can be further formed thereon.
When the base layer made of TaN is not formed on the substrate 7, the substrate 7 is covered with a shutter or the like until the nitrogen partial pressure in the vacuum chamber 10 becomes a nitrogen partial pressure at which a film made of α-tantalum is formed. It is only necessary to prevent the base layer made of
The surface of the substrate 7 on which the α-tantalum film is formed is not particularly limited, and may be, for example, the surface of a substrate made of silicon or the surface of a substrate made of silicon oxide. Further, a surface on which a thin film made of TaN or the like is previously formed as a base layer may be used.
　前述のように第２のプロセスガスを設定することによって、αタンタルからなる被膜が形成される窒素分圧となることは、本発明者らの研究によって得られた図２の結果から明らかである。すなわち、図２に示す通り不活性ガスとともに微量の窒素ガスを流すことにより、窒素ガスが図２の流量Ｆのときに成膜されたＴａ薄膜の比抵抗が極小となる傾向を見出した。
　図２の横軸は、真空槽１０に導入される窒素ガスの流量（単位はｓｃｃｍ）を示す
　図２の縦軸は、横軸に示す窒素ガス流量で真空槽１０を十分に安定させた後、スパッタリングすることによって形成されたＴａ薄膜の比抵抗（単位はμΩ・ｃｍ）を示す。なお、形成されたＴａ薄膜の厚さは約１００Åであり、その下地層はＴａＮである。 By setting the second process gas as described above, it is clear from the results of FIG. 2 obtained by the present inventors that the nitrogen partial pressure at which a film made of α-tantalum is formed is obtained. . That is, as shown in FIG. 2, it was found that the specific resistance of the Ta thin film formed when the nitrogen gas was flow rate F in FIG.
2 indicates the flow rate of nitrogen gas introduced into the vacuum chamber 10 (unit: sccm). The vertical axis of FIG. 2 indicates that the vacuum chamber 10 is sufficiently stabilized at the nitrogen gas flow rate indicated on the horizontal axis. The specific resistance (unit: μΩ · cm) of the Ta thin film formed by sputtering is shown. The formed Ta thin film has a thickness of about 100 mm, and the underlying layer is TaN.
　Ｘ線回折の結果から、図２の窒素流量が５ｓｃｃｍ以上で形成されたＴａ薄膜はＴａＮからなる薄膜であることが確認された。
　窒素流量が５ｓｃｃｍ以下では、形成されるＴａ薄膜の比抵抗はＴａＮ薄膜よりも低くなり、窒素流量Ｆが０．１ｓｃｃｍ以上１．０ｓｃｃｍ以下の範囲で比抵抗が最も低下する。この窒素流量の範囲で形成されたＴａ薄膜は、Ｘ線回折の結果から、αタンタルからなる薄膜であることが確認された。
　一方、窒素流量が０ｓｃｃｍでは、比抵抗がＴａＮからなる薄膜と同程度である。このＴａ薄膜は、Ｘ線回折の結果から、βタンタルからなる薄膜であることが確認された。 From the result of X-ray diffraction, it was confirmed that the Ta thin film formed at a nitrogen flow rate of 5 sccm or more in FIG. 2 is a thin film made of TaN.
When the nitrogen flow rate is 5 sccm or less, the specific resistance of the formed Ta thin film is lower than that of the TaN thin film, and the specific resistance decreases most when the nitrogen flow rate F is in the range of 0.1 sccm to 1.0 sccm. From the result of X-ray diffraction, it was confirmed that the Ta thin film formed in this nitrogen flow rate range was a thin film made of α-tantalum.
On the other hand, when the nitrogen flow rate is 0 sccm, the specific resistance is comparable to that of a thin film made of TaN. From the result of X-ray diffraction, this Ta thin film was confirmed to be a thin film made of β-tantalum.
　次に、実施例により本実施形態をさらに詳細に説明するが、本発明はこれらの例によって限定されるものではない。
　実施例１および比較例１～２では、図１に示すスパッタ装置１を用いてスパッタリングを行った。 Next, the present embodiment will be described in more detail with reference to examples, but the present invention is not limited to these examples.
In Example 1 and Comparative Examples 1 and 2, sputtering was performed using the sputtering apparatus 1 shown in FIG.
［実施例１］
　表１に示す工程Ａ，Ｃ，Ｂ，Ｄの順でプロセスガスを調整してプラズマを制御し、スパッタ法によって、シリコンウエハ２１上にＴａＮからなる下地層２２を形成し、さらにその上にαタンタルからなる被膜２３を成膜した（図３Ａ参照）。 [Example 1]
A process gas is adjusted in the order of steps A, C, B, and D shown in Table 1 to control plasma, and a base layer 22 made of TaN is formed on the silicon wafer 21 by sputtering, and α is further formed thereon. A film 23 made of tantalum was formed (see FIG. 3A).
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　工程Ａでは、真空槽１０にＡｒ流量１０．０ｓｃｃｍ及び窒素ガス流量３０．０ｓｃｃｍの第一のプロセスガスをガス導入口２から導入し、真空槽１０のガス流量を安定させるために１５秒間保った。
　つぎに、工程Ｃでは、プラズマ発生用直流電源９の電力を１８．０ｋＷ、基体バイアス高周波電源１３（１．０～１３．５６ＭＨｚ）の電力を６００Ｗに設定し、工程Ａと同じプロセスガスを用いてスパッタリングを３．０秒間行い、シリコンウエハ２１上にＴａＮからなる下地層２２（厚さ：約２０ｎｍ）を形成した。
　つづいて、工程Ｂでは、プラズマ発生用直流電源９の電力及び基体バイアス高周波電源１３の電力を工程Ｃと同じ条件に保ちながら、第１のプロセスガスから第２のプロセスガスへ切り替えた。その第２のプロセスガスは、Ａｒ流量１０．０ｓｃｃｍ及び窒素ガス流量０．０ｓｃｃｍとした。第２のプロセスガスに切り替えて１５．０秒間のスパッタリングを行い、前記ＴａＮからなる下地層上にαタンタルからなる被膜２３（厚さ：約１００ｎｍ）を成膜した。
　最後の工程Ｄでは、プラズマ発生用直流電源９及び基体バイアス高周波電源１３を切って、プロセスガスを停止して、１５．０秒間プロセスガスの排気を行った。 In step A, a first process gas having an Ar flow rate of 10.0 sccm and a nitrogen gas flow rate of 30.0 sccm was introduced into the vacuum chamber 10 from the gas inlet 2 and maintained for 15 seconds in order to stabilize the gas flow rate of the vacuum chamber 10. .
Next, in step C, the power of the plasma generating DC power source 9 is set to 18.0 kW, the power of the substrate bias high frequency power source 13 (1.0 to 13.56 MHz) is set to 600 W, and the same process gas as in step A is used. Sputtering was then performed for 3.0 seconds to form a base layer 22 (thickness: about 20 nm) made of TaN on the silicon wafer 21.
Subsequently, in step B, the first process gas was switched to the second process gas while maintaining the power of the plasma generating DC power supply 9 and the power of the substrate bias high frequency power supply 13 at the same conditions as in step C. The second process gas had an Ar flow rate of 10.0 sccm and a nitrogen gas flow rate of 0.0 sccm. Switching to the second process gas, sputtering was performed for 15.0 seconds, and a film 23 (thickness: about 100 nm) made of α-tantalum was formed on the underlayer made of TaN.
In the final step D, the plasma generating DC power supply 9 and the substrate bias high frequency power supply 13 were turned off, the process gas was stopped, and the process gas was exhausted for 15.0 seconds.
　成膜したαタンタルからなる被膜２３をＸ線回折（波長λ＝１．５４１８Å）で分析したところ、図３Ｂに示すように、２θ＝３８．３度付近にαタンタルの（１１０）のシャープなピークがあった。一方、２θ＝３３．５度付近にβタンタルの（００２）のピークはなかった。この結果から、成膜した被膜は、βタンタルを含まない、αタンタルからなる被膜であることが確認された。 The film 23 made of α-tantalum was analyzed by X-ray diffraction (wavelength λ = 1.5418 mm), and as shown in FIG. 3B, (110) sharpness of α-tantalum was found around 2θ = 38.3 degrees. There was a peak. On the other hand, there was no (002) peak of β-tantalum around 2θ = 33.5 degrees. From this result, it was confirmed that the film formed was a film made of α-tantalum that did not contain β-tantalum.
［比較例１］
　表２に示す工程Ｓ１０１～Ｓ１０５の順でプロセスガスを調整してプラズマを制御し、スパッタ法によって、シリコンウエハ２４上にＴａＮからなる下地層２５を形成し、さらにその上にβタンタル及びαタンタルからなるタンタルの被膜２６を成膜した（図４Ａ参照）。 [Comparative Example 1]
The plasma is controlled by adjusting the process gas in the order of steps S101 to S105 shown in Table 2, and a base layer 25 made of TaN is formed on the silicon wafer 24 by sputtering, and β tantalum and α tantalum are further formed thereon. A tantalum coating 26 was formed (see FIG. 4A).
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　工程Ｓ１０１では、真空槽１０にＡｒ流量１０．０ｓｃｃｍ及び窒素ガス流量３０．０ｓｃｃｍのプロセスガスをガス導入口２から導入し、真空槽１０のガス流量を安定させるために１５秒間保った。
　つぎに、工程Ｓ１０２では、プラズマ発生用直流電源９の電力を１８．０ｋＷ、基体バイアス高周波電源１３（１．０～１３．５６ＭＨｚ）の電力を６００Ｗに設定し、工程Ｓ１０１と同じプロセスガスを用いてスパッタリングを３．０秒間行い、シリコンウエハ２４上にＴａＮからなる薄膜層２５（厚さ：約２０ｎｍ）を形成した。
　その後、工程Ｓ１０３では、Ａｒ流量１０．０ｓｃｃｍ及び窒素ガス流量０．０ｓｃｃｍのプロセスガスに切り替えて２０秒間保ち、真空槽１０中から窒素ガスを除いて真空槽１０をＡｒ雰囲気にした。
　つづいて、工程Ｓ１０４では、プラズマ発生用直流電源９の電力及び基体バイアス高周波電源１３の電力を工程Ｓ１０２と同じ条件に設定し、プロセスガスは工程Ｓ１０３と同じ条件に保って１５．０秒間のスパッタリングを行い、前記ＴａＮからなる下地層２５上にβタンタル及びαタンタルからなる被膜２６（厚さ：約１００ｎｍ）を成膜した。
　最後の工程Ｓ１０５では、プラズマ発生用の直流電源９及び基体バイアス高周波電源１３を切って、プロセスガスを停止して、１５．０秒間プロセスガスの排気を行った。 In step S101, a process gas having an Ar flow rate of 10.0 sccm and a nitrogen gas flow rate of 30.0 sccm was introduced into the vacuum chamber 10 from the gas inlet 2 and maintained for 15 seconds in order to stabilize the gas flow rate of the vacuum chamber 10.
Next, in step S102, the power of the plasma generating DC power source 9 is set to 18.0 kW, the power of the substrate bias high-frequency power source 13 (1.0 to 13.56 MHz) is set to 600 W, and the same process gas as in step S101 is used. Then, sputtering was performed for 3.0 seconds, and a thin film layer 25 (thickness: about 20 nm) made of TaN was formed on the silicon wafer 24.
Thereafter, in step S103, the process gas was switched to a process gas having an Ar flow rate of 10.0 sccm and a nitrogen gas flow rate of 0.0 sccm and maintained for 20 seconds, and nitrogen gas was removed from the vacuum chamber 10 to make the vacuum chamber 10 an Ar atmosphere.
Subsequently, in step S104, the power of the plasma generating DC power source 9 and the power of the substrate bias high frequency power source 13 are set to the same conditions as in step S102, and the process gas is kept under the same conditions as in step S103 for 15.0 seconds of sputtering. A film 26 (thickness: about 100 nm) made of β tantalum and α tantalum was formed on the underlayer 25 made of TaN.
In the last step S105, the plasma generating DC power supply 9 and the substrate bias high frequency power supply 13 were turned off, the process gas was stopped, and the process gas was exhausted for 15.0 seconds.
　成膜したβタンタル及びαタンタルからなる被膜２６をＸ線回折（波長λ＝１．５４１８Å）で分析したところ、図４Ｂに示すように、２θ＝３８．３度付近にαタンタルの（１１０）のブロードなピークがあった。一方、２θ＝３３．５度付近にβタンタルの（００２）の比較的シャープなピークがあった。この結果から、成膜した被膜は、βタンタル及びαタンタルからなる被膜であることが確認された。 The film 26 made of β tantalum and α tantalum was analyzed by X-ray diffraction (wavelength λ = 1.5418 mm), and as shown in FIG. 4B, α-tantalum (110) was found around 2θ = 38.3 degrees. There was a broad peak. On the other hand, there was a (002) relatively sharp peak of β-tantalum in the vicinity of 2θ = 33.5 °. From this result, it was confirmed that the film formed was a film made of β tantalum and α tantalum.
［比較例２］
　表３に示す工程Ｓ２０１～Ｓ２０４の順でプロセスガスを調整してプラズマを制御し、スパッタ法によって、シリコンウエハ２７上にβタンタルからなるタンタルの被膜２８を成膜した（図５Ａ参照）。 [Comparative Example 2]
The plasma was controlled by adjusting the process gas in the order of steps S201 to S204 shown in Table 3, and a tantalum film 28 made of β-tantalum was formed on the silicon wafer 27 by sputtering (see FIG. 5A).
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　工程Ｓ２０１では、真空槽１０にＡｒ流量１０．０ｓｃｃｍ及び窒素ガス流量０．０ｓｃｃｍのプロセスガスをガス導入口２から導入し、真空槽１０のガス流量を安定させるために１５秒間保った。
　つぎに、工程Ｓ２０２では、プラズマ発生用の直流電源９の電力を１８．０ｋＷ、基体バイアス高周波電源１３（１．０～１３．５６ＭＨｚ）の電力を６００Ｗに設定し、工程Ｓ２０１と同じプロセスガスを用いてスパッタリングを３．０秒間行い、シリコンウエハ２７上にβタンタルからなる被膜（厚さ：約２０ｎｍ）を形成した。
　その後、工程Ｓ２０３では、工程Ｓ２０２と同じ条件でさらに１０．０秒間のスパッタリングを行い、さらにβタンタルからなる被膜２８（厚さ：約１００ｎｍ）を成膜した。
　最後の工程Ｓ２０４では、プラズマ発生用の直流電源９及び基体バイアス高周波電源１３を切って、プロセスガスを停止して、１５．０秒間プロセスガスの排気を行った。 In step S201, a process gas having an Ar flow rate of 10.0 sccm and a nitrogen gas flow rate of 0.0 sccm was introduced into the vacuum chamber 10 from the gas inlet 2 and maintained for 15 seconds in order to stabilize the gas flow rate of the vacuum chamber 10.
Next, in step S202, the power of the DC power source 9 for generating plasma is set to 18.0 kW, the power of the substrate bias high frequency power source 13 (1.0 to 13.56 MHz) is set to 600 W, and the same process gas as in step S201 is used. Sputtering was performed for 3.0 seconds, and a film (thickness: about 20 nm) made of β-tantalum was formed on the silicon wafer 27.
Thereafter, in step S203, sputtering was further performed for 10.0 seconds under the same conditions as in step S202, and a film 28 (thickness: about 100 nm) made of β-tantalum was further formed.
In the final step S204, the plasma generating DC power supply 9 and the substrate bias high frequency power supply 13 were turned off, the process gas was stopped, and the process gas was exhausted for 15.0 seconds.
　成膜したβタンタルからなる被膜２８をＸ線回折（波長λ＝１．５４１８Å）で分析したところ、図５Ｂに示すように、２θ＝３８．３度付近にαタンタルの（１１０）のピークはなかった。一方、２θ＝３３．５度付近にβタンタルの（００２）のシャープなピークがあった。この結果から、成膜した被膜は、βタンタルからなる被膜であることが確認された。 When the film 28 made of β-tantalum was analyzed by X-ray diffraction (wavelength λ = 1.5418 mm), as shown in FIG. 5B, the peak of (110) of α-tantalum was around 2θ = 38.3 degrees. There wasn't. On the other hand, there was a sharp (002) peak of β tantalum in the vicinity of 2θ = 33.5 °. From this result, it was confirmed that the film formed was a film made of β tantalum.
１…スパッタ装置、２…ガス導入口、３…真空排気口、４…カソード電極、５…Ｔａターゲット、６…基体電極、７…基体、８…磁気回路、９…直流電源、１０…真空槽、１１…ヒーター、１１ａ…絶縁部、１３…高周波電源、２１…基体（シリコンウエハ）、２２…下地層、２３…αタンタルからなる被膜、２４…基体、２５…下地層、２６…βタンタル及びαタンタルからなる被膜、２７…基体、２８…βタンタルからなる被膜。 DESCRIPTION OF SYMBOLS 1 ... Sputtering device, 2 ... Gas introduction port, 3 ... Vacuum exhaust port, 4 ... Cathode electrode, 5 ... Ta target, 6 ... Base electrode, 7 ... Base | substrate, 8 ... Magnetic circuit, 9 ... DC power supply, 10 ... Vacuum chamber , 11 ... heater, 11a ... insulating part, 13 ... high frequency power supply, 21 ... base (silicon wafer), 22 ... base layer, 23 ... coating made of alpha tantalum, 24 ... base, 25 ... base layer, 26 ... beta tantalum and Coating made of α tantalum, 27... substrate, 28.

Claims (5)

  1. 　スパッタ法を用いて、αタンタルからなる被膜を基体に成膜する方法であって、
    　不活性ガス及び窒素ガスからなる第１のプロセスガスを真空槽に導入し、
    　前記第１のプロセスガス導入の後、
    　αタンタルからなる被膜が形成される窒素分圧となるように、不活性ガス及び窒素ガスのうち少なくとも一つからなる第２のプロセスガスを前記真空槽に導入してプラズマを制御することにより、αタンタルからなる被膜を基体に形成する
    ことを特徴とするαタンタルからなる被膜の成膜方法。     A method of forming a film of α tantalum on a substrate using a sputtering method,
    Introducing a first process gas comprising an inert gas and a nitrogen gas into the vacuum chamber;
    After the introduction of the first process gas,
    By controlling the plasma by introducing a second process gas consisting of at least one of an inert gas and a nitrogen gas into the vacuum chamber so as to have a nitrogen partial pressure at which a film made of α-tantalum is formed, A method for forming a film made of α-tantalum, comprising forming a film made of α-tantalum on a substrate.
  2. 　前記第１のプロセスガス導入の後、
    　窒化タンタルからなる下地層を基体に形成し、
    　前記窒化タンタルからなる下地層を前記基体に形成した後、
    　前記αタンタルからなる被膜を前記基体に形成する
    ことを特徴とする請求項１に記載のαタンタルからなる被膜の成膜方法。     After the introduction of the first process gas,
    An underlayer made of tantalum nitride is formed on the substrate,
    After forming the base layer made of the tantalum nitride on the substrate,
    2. The method for forming a film made of α-tantalum according to claim 1, wherein the film made of α-tantalum is formed on the substrate.
  3. 　前記基体の材料として、シリコンを用いることを特徴とする請求項１又は２に記載のαタンタルからなる被膜の成膜方法。 3. The method for forming a film made of α-tantalum according to claim 1, wherein silicon is used as a material of the substrate.
  4. 　前記基体の材料として、酸化シリコン或いは石英を用いることを特徴とする請求項１又は２に記載のαタンタルからなる被膜の成膜方法。 3. The method for forming a film made of α-tantalum according to claim 1 or 2, wherein silicon oxide or quartz is used as a material of the substrate.
  5. 　請求項１乃至請求項４に記載の成膜方法によって形成されたαタンタルからなる被膜であって、
    　前記基体から前記αタンタルからなる被膜に向かう方向において、前記αタンタルからなる被膜の前位置及び後位置の少なくともいずれか一方に、導体又は半導体が配されていることを特徴とするαタンタルからなる被膜。     A film made of α-tantalum formed by the film forming method according to claim 1, wherein
    A conductor or a semiconductor is arranged at least one of a front position and a rear position of the film made of α tantalum in a direction from the base toward the film made of α tantalum. Coating.
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CN111926289B (en) * 2020-08-19 2022-10-21 重庆文理学院 Preparation method of tantalum coating

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