[go: up one dir, main page]

US20050003663A1 - Integrated circuit having barrier metal surface treatment prior to Cu deposition - Google Patents

Integrated circuit having barrier metal surface treatment prior to Cu deposition Download PDF

Info

Publication number
US20050003663A1
US20050003663A1 US10/903,610 US90361004A US2005003663A1 US 20050003663 A1 US20050003663 A1 US 20050003663A1 US 90361004 A US90361004 A US 90361004A US 2005003663 A1 US2005003663 A1 US 2005003663A1
Authority
US
United States
Prior art keywords
barrier metal
metal layer
copper film
integrated circuit
subjecting
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US10/903,610
Inventor
Wei Pan
Jer-shen Maa
David Evans
Sheng Hsu
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sharp Laboratories of America Inc
Original Assignee
Sharp Laboratories of America Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sharp Laboratories of America Inc filed Critical Sharp Laboratories of America Inc
Priority to US10/903,610 priority Critical patent/US20050003663A1/en
Publication of US20050003663A1 publication Critical patent/US20050003663A1/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table 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
    • 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
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
    • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
    • H01L21/76838—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the conductors
    • H01L21/76841—Barrier, adhesion or liner layers
    • H01L21/76843—Barrier, adhesion or liner layers formed in openings in a dielectric
    • 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
    • C23C16/02—Pretreatment of the material to be coated
    • C23C16/0209—Pretreatment of the material to be coated by heating
    • 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
    • C23C16/06—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 metallic material
    • C23C16/18—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 metallic material from metallo-organic compounds
    • 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 potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table 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 Table
    • H01L21/28556—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 Table by chemical means, e.g. CVD, LPCVD, PECVD, laser CVD
    • 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
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
    • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
    • H01L21/76838—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the conductors
    • H01L21/76841—Barrier, adhesion or liner layers
    • H01L21/76853—Barrier, adhesion or liner layers characterized by particular after-treatment steps
    • H01L21/76861—Post-treatment or after-treatment not introducing additional chemical elements into the layer
    • H01L21/76864—Thermal treatment
    • 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
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
    • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
    • H01L21/76838—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the conductors
    • H01L21/76841—Barrier, adhesion or liner layers
    • H01L21/76871—Layers specifically deposited to enhance or enable the nucleation of further layers, i.e. seed layers
    • H01L21/76876—Layers specifically deposited to enhance or enable the nucleation of further layers, i.e. seed layers for deposition from the gas phase, e.g. CVD

Definitions

  • This invention relates to a method of treating a barrier metal surface prior to copper deposition thereon to improve the adhesion and trench filling characteristics of the copper deposition and, more particularly, to a method of pre-treating a barrier metal surface during a rapid thermal process in a vacuum or with a non-reactive gas such as hydrogen, argon or helium in a temperature range of 200 to 550 degrees Celsius, prior to the deposition of the copper film.
  • a non-reactive gas such as hydrogen, argon or helium in a temperature range of 200 to 550 degrees Celsius
  • Two of the challenges faced in the metallization process steps of integrated circuit (IC) fabrication include achieving good adhesion of a copper (Cu) film to the underlying barrier metal layer, and achieving good gap filling characteristics of the Cu film in narrow trenches or vias.
  • Cu copper
  • CVD chemical vapor deposition
  • the method of the present invention provides a rapid thermal process (RTP) wherein silicon wafers that are pre-coated with barrier metal films by either in-situ or ex-situ CVD or physical vapor deposition (PVD) are pre-treated, prior to deposition of a Cu film thereon, in a temperature range of between 300 and 550 degrees Celsius in a non-reactive gas such as hydrogen gas (H 2 ), argon (Ar), or helium (He), or in an ambient vacuum.
  • a non-reactive gas such as hydrogen gas (H 2 ), argon (Ar), or helium (He)
  • the chamber pressure typically is between 0.1 mTorr and 20 Torr, and the RTP time typically is between 30 to 100 seconds.
  • the process disclosed herein is an enabling technology for the use of metal organic CVD (MOCVD) Cu in IC fabrication.
  • MOCVD metal organic CVD
  • the invention comprises a method of pre-treating a barrier metal layer of a partially finished integrated circuit device prior to the deposition of a copper film thereon, comprising the steps of: providing a partially finished integrated circuit device including a barrier metal layer; subjecting said barrier metal layer to a temperature greater than 200 degrees Celsius for at least thirty seconds to form a pre-treated barrier metal layer; and depositing a copper film on said pre-treated barrier metal layer.
  • the invention further comprises a method of pre-treating a barrier metal layer of a partially finished integrated circuit device for the deposition of a copper film thereon, comprising the steps of: providing a partially finished integrated circuit device including a barrier metal layer having a trench or a via therein; subjecting said barrier metal layer to a temperature greater than 200 degrees Celsius for at least thirty seconds in an atmosphere chosen from the group consisting of: an ambient vacuum, hydrogen gas, argon gas, and helium gas to form a pre-treated barrier metal layer; and thereafter depositing a copper film on said pre-treated barrier metal layer and throughout said trench.
  • the invention also comprises an integrated circuit device manufactured by the process of: providing a partially finished integrated circuit device including a barrier metal layer; subjecting said barrier metal layer to a temperature greater than 200 degrees Celsius for at least thirty seconds; and thereafter depositing a copper film on said barrier metal layer.
  • an object of the invention is to provide a method of pre-treating a barrier metal layer so as to improve the deposition of a Cu film thereon.
  • a further object of the invention is to provide a method of pre-treating a barrier metal layer so as to improve the adhesion of a Cu film thereto.
  • Another object of the invention is to provide a method of pre-treating a barrier metal film so as to improve the trench and via filling characteristics of Cu applied thereto.
  • a further object of the invention is to provide a method of reducing variations in Cu deposition caused by Cu precursors.
  • FIG. 1 is a schematic of a barrier metal layer deposited on a substrate.
  • FIG. 2 is a schematic of the barrier metal layer being subjected to the pre-treatment rapid thermal process step of the present invention.
  • FIG. 3 is a schematic of the copper deposition step of the process of the present invention.
  • FIG. 4 is a schematic of the copper layer deposited on the barrier metal layer after the rapid thermal pre-treatment process step.
  • FIG. 5 is a flow diagram of the process of the present invention.
  • FIG. 1 shows a partially processed integrated circuit (IC) device 10 including a substrate 12 , a low dielectric constant (k) interlayer dielectric (ILD) layer 14 and a barrier metal layer 16 positioned thereon.
  • the silicon wafers 10 typically are pre-coated with barrier metal films 16 by either in-situ or ex-situ CVD or physical vapor deposition (PVD) prior to deposition of a Cu film thereon.
  • Barrier layer 16 may comprise titanium nitride (TiN), tantalum nitride (TaN), or other such barrier metals as known in the art.
  • Layer 14 includes a trench or via 18 which extends through layer 14 and to substrate 12 .
  • substrate 12 may comprise any number and/or variety of layers or devices but is referred to merely as a substrate for ease of illustration.
  • Barrier metal layer 16 is evenly deposited, or otherwise placed, completely over layer 14 and on the side walls and bottom surface of trench 18 .
  • Trench 18 with barrier metal layer 16 extending downwardly therein, has a depth 20 similar to the thickness 22 of layer 14 .
  • the term trench means any type of depression or recess as known in the art, for example, a trench or a via.
  • the trench also includes a width or diameter 24 which may be quite narrow. In particular, width 24 may be on the order of 0.13 ⁇ m or thereabout, and generally is in the range of less than 0.15 ⁇ m. Due to the narrow width of trench or via 18 , a copper (Cu) film is not easily deposited on walls 26 and 28 , and on bottom surface 30 of the trench. Moreover, prior art processing steps which desire to achieve good adhesion of the Cu film to the barrier metal layer, often result in poor gap filling characteristics of the Cu film in the trench or via.
  • Cu copper
  • FIG. 2 shows the IC device of FIG. 1 subjected to the pre-treatment rapid thermal process step, indicated by arrows 32 .
  • Arrows 32 represent the conditions of the RTP step which include subjecting barrier metal layer 16 to a non-reactive gas such as hydrogen gas (H 2 ), argon (Ar), or helium (He), or to an ambient vacuum.
  • the temperature range of the process typically is greater than 200 degrees Celsius, and preferably is between 250 and 550 degrees Celsius.
  • the chamber pressure typically is between 0.1 mTorr and 20 Torr, and the RTP time typically is between 30 to 100 seconds.
  • This pre-treatment process eliminates variations in the subsequently deposited Cu film which may be caused by Cu precursors. In other words, the RTP disclosed herein is insensitive to variations in precursor composition, volatility, and other precursor variables.
  • barrier metal layer 16 is ready for the deposition of the copper film thereon.
  • FIG. 3 is a schematic of the copper deposition step of the process of the present invention.
  • the Cu deposition step is represented by arrows 34 .
  • the deposition of the Cu film may be by physical vapor deposition (PVD), chemical vapor deposition (CVD), or any other known means of placing a copper film on a barrier metal layer.
  • PVD physical vapor deposition
  • CVD chemical vapor deposition
  • copper deposition step 34 comprises CVD in order to achieve a uniform and thin layer of copper material on pre-treated metal barrier layer 16 ′.
  • the conditions of the CVD of Cu are well known in the art and will not be discussed herein.
  • FIG. 4 is a schematic of a copper layer 36 deposited on pre-treated barrier metal layer 16 ′ after the rapid thermal pre-treatment process step 32 described above.
  • Performing the rapid thermal process step before the deposition of the Cu film results in a thin, shiny, densely nucleated, and adhesive Cu film 36 being deposited on a variety of barrier metal surfaces such as TiN or TaN.
  • the copper film 36 is evenly distributed on layer 16 , including throughout trench or via 18 .
  • Cu layer 36 is deposited in trench or via 18 so that the entire trench or via is filled with copper material and does not include key holes or other such variations in the copper layer.
  • the adhesive Cu film 36 deposited on pre-treated barrier metal layer 16 ′ withstands traditional tape tests and does not flake or peel from pre-treated barrier metal layer 16 ′, as do the deposited Cu films of the prior art. Accordingly, the deposited Cu film has superior adhesive and trench filling characteristics compared to prior art Cu deposition processes. Moreover, the rapid thermal process step of the present invention has isotropic characteristics which is an advantage of this process in comparison to other surface treatments, such as plasma treatments. In particular, the rapid thermal process step 32 of the present invention results in better step coverage and trench fill. Accordingly, the process disclosed herein is an enabling technology for the use of metal organic CVD (MOCVD) Cu in the fabrication of IC devices.
  • MOCVD metal organic CVD
  • FIG. 5 is a flow diagram of the process of the present invention.
  • Step 50 comprises providing a partially processed integrated circuit (IC) device 10 including a substrate 12 , a low dielectric constant (k) interlayer dielectric (ILD) layer 14 and a barrier metal layer 16 positioned thereon, wherein layer 16 typically includes one or more trenches or vias 18 .
  • the IC device is then subjected to the pre-treatment rapid thermal process step.
  • the first step 52 of the pre-treatment process involves choosing the gas condition that will be utilized.
  • the conditions of step 52 include subjecting barrier metal layer 16 to a non-reactive gas such as Hydrogen gas (H 2 ), Argon (Ar), or Helium (He), or to an ambient vacuum.
  • H 2 Hydrogen gas
  • Argon Argon
  • He Helium
  • Step 54 includes choosing the temperature of the process, which typically is greater than 200 degrees Celsius, and preferably is between 250 and 550 degrees Celsius.
  • Step 56 includes choosing the chamber pressure, which typically is between 0.1 mTorr and 20 Torr.
  • Step 58 includes choosing the process time, which typically is between 30 to 100 seconds.
  • Step 60 includes subjecting the IC device, and in particular barrier metal layer 16 , to the vacuum/gas, temperature, and pressure chosen above, for the chosen time period. This pre-treatment process results in a pre-treated barrier metal layer, shown as layer 16 ′ in FIG. 4 , which is ready for the deposition of a copper film thereon.
  • Step 62 includes depositing a copper film on pre-treated barrier layer 16 ′ by process steps as known in the art.
  • the deposition of the Cu film in step 62 may be by physical vapor deposition (PVD), chemical vapor deposition (CVD), or any other known means of placing a copper film on the pre-treated barrier metal layer.
  • PVD physical vapor deposition
  • CVD chemical vapor deposition
  • the Cu film is deposited by CVD due to its superior film application characteristics on barrier metal layers.
  • the deposition of the barrier layer on the substrate, the RTP treatment, and the deposition of the Cu film are all accomplished in-situ (without a vacuum break, but in different process chambers), thereby facilitating efficiency and cost effectiveness in the fabrication process.
  • the steps may be undertaken ex-situ (with a vacuum break, and exposed to air), or in a combination of in-situ and ex-situ steps.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • General Physics & Mathematics (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Internal Circuitry In Semiconductor Integrated Circuit Devices (AREA)
  • Chemical Vapour Deposition (AREA)

Abstract

A rapid thermal process (RTP) provides steps wherein silicon wafers that are pre-coated with barrier metal films by either in-situ or ex-situ CVD or physical vapor deposition (PVD) are pre-treated, prior to deposition of a Cu film thereon, in a temperature range of between 250 and 550 degrees Celsius in a non-reactive gas such as hHydrogen gas (H2), argon (Ar), or helium (He), or in an ambient vacuum. The chamber pressure typically is between 0.1 mTorr and 20 Torr, and the RTP time typically is between 30 to 100 seconds. Performing this rapid thermal process before deposition of the Cu film results in a thin, shiny, densely nucleated, and adhesive Cu film deposited on a variety of barrier metal surfaces. The pre-treatment process eliminates variations in the deposited Cu film caused by Cu precursors and is insensitive to variation in precursor composition, volatility, and other precursor variables. Accordingly, the process disclosed herein is an enabling technology for the use of metal organic CVD (MOCVD) Cu in IC fabrication.

Description

    CROSS REFERENCE TO RELATED APPLICATION
  • This application is a divisional of application Ser. No. 09/820,068, filed Mar. 28, 2001, entitled “Method of Barrier Metal Surface Treatment Prior to Cu Deposition to Improve Adhesion and. Trench Filling Characteristics,” invented by Pan et al.
    • FIELD OF THE INVENTION
  • This invention relates to a method of treating a barrier metal surface prior to copper deposition thereon to improve the adhesion and trench filling characteristics of the copper deposition and, more particularly, to a method of pre-treating a barrier metal surface during a rapid thermal process in a vacuum or with a non-reactive gas such as hydrogen, argon or helium in a temperature range of 200 to 550 degrees Celsius, prior to the deposition of the copper film. The rapid thermal pre-treatment process improves the adhesion and trench filling characteristics of the subsequently deposited copper film.
    • BACKGROUND OF THE INVENTION
  • Two of the challenges faced in the metallization process steps of integrated circuit (IC) fabrication include achieving good adhesion of a copper (Cu) film to the underlying barrier metal layer, and achieving good gap filling characteristics of the Cu film in narrow trenches or vias. In particular, it is difficult to fill narrow trenches or vias, having a diameter of 0.13 μm or less, with copper (Cu) deposited by chemical vapor deposition (CVD), and at the same time maintain good adhesion of the Cu film to the underlying barrier metal film. Inadequate adhesion of the Cu film or uneven filling of the Cu film in the narrow trenches will result in an unusable or unreliable integrated circuit (IC) device.
  • In order to increase adhesion and gap filling characteristics of the Cu films, various pre-treatments and precursor compounds have been used. However, these pre-treatments and precursor compounds often result in variations in the deposited Cu film. These variations in the deposited Cu film are a severe problem which heretofore has hindered the application of CVD Cu films in IC processing.
    • SUMMARY OF THE INVENTION
  • The method of the present invention provides a rapid thermal process (RTP) wherein silicon wafers that are pre-coated with barrier metal films by either in-situ or ex-situ CVD or physical vapor deposition (PVD) are pre-treated, prior to deposition of a Cu film thereon, in a temperature range of between 300 and 550 degrees Celsius in a non-reactive gas such as hydrogen gas (H2), argon (Ar), or helium (He), or in an ambient vacuum. The chamber pressure typically is between 0.1 mTorr and 20 Torr, and the RTP time typically is between 30 to 100 seconds. Performing this rapid thermal process before the deposition of the Cu film results in a thin, shiny, densely nucleated, and adhesive Cu film deposited on a variety of barrier metal surfaces. The pre-treatment process eliminates variations in the deposited Cu film caused by Cu precursors. In other words, the RTP disclosed herein is insensitive to variation in precursor composition, volatility, and other precursor variables. Accordingly, the process disclosed herein is an enabling technology for the use of metal organic CVD (MOCVD) Cu in IC fabrication.
  • In particular, the invention comprises a method of pre-treating a barrier metal layer of a partially finished integrated circuit device prior to the deposition of a copper film thereon, comprising the steps of: providing a partially finished integrated circuit device including a barrier metal layer; subjecting said barrier metal layer to a temperature greater than 200 degrees Celsius for at least thirty seconds to form a pre-treated barrier metal layer; and depositing a copper film on said pre-treated barrier metal layer.
  • The invention further comprises a method of pre-treating a barrier metal layer of a partially finished integrated circuit device for the deposition of a copper film thereon, comprising the steps of: providing a partially finished integrated circuit device including a barrier metal layer having a trench or a via therein; subjecting said barrier metal layer to a temperature greater than 200 degrees Celsius for at least thirty seconds in an atmosphere chosen from the group consisting of: an ambient vacuum, hydrogen gas, argon gas, and helium gas to form a pre-treated barrier metal layer; and thereafter depositing a copper film on said pre-treated barrier metal layer and throughout said trench.
  • The invention also comprises an integrated circuit device manufactured by the process of: providing a partially finished integrated circuit device including a barrier metal layer; subjecting said barrier metal layer to a temperature greater than 200 degrees Celsius for at least thirty seconds; and thereafter depositing a copper film on said barrier metal layer.
  • Accordingly, an object of the invention is to provide a method of pre-treating a barrier metal layer so as to improve the deposition of a Cu film thereon.
  • A further object of the invention is to provide a method of pre-treating a barrier metal layer so as to improve the adhesion of a Cu film thereto.
  • Another object of the invention is to provide a method of pre-treating a barrier metal film so as to improve the trench and via filling characteristics of Cu applied thereto.
  • A further object of the invention is to provide a method of reducing variations in Cu deposition caused by Cu precursors.
    • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 is a schematic of a barrier metal layer deposited on a substrate.
  • FIG. 2 is a schematic of the barrier metal layer being subjected to the pre-treatment rapid thermal process step of the present invention.
  • FIG. 3 is a schematic of the copper deposition step of the process of the present invention.
  • FIG. 4 is a schematic of the copper layer deposited on the barrier metal layer after the rapid thermal pre-treatment process step.
  • FIG. 5 is a flow diagram of the process of the present invention.
    • DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
  • Turning now to the drawings, FIG. 1 shows a partially processed integrated circuit (IC) device 10 including a substrate 12, a low dielectric constant (k) interlayer dielectric (ILD) layer 14 and a barrier metal layer 16 positioned thereon. The silicon wafers 10 typically are pre-coated with barrier metal films 16 by either in-situ or ex-situ CVD or physical vapor deposition (PVD) prior to deposition of a Cu film thereon. Barrier layer 16 may comprise titanium nitride (TiN), tantalum nitride (TaN), or other such barrier metals as known in the art. Layer 14 includes a trench or via 18 which extends through layer 14 and to substrate 12. Those skilled in the art will understand that substrate 12 may comprise any number and/or variety of layers or devices but is referred to merely as a substrate for ease of illustration. Barrier metal layer 16 is evenly deposited, or otherwise placed, completely over layer 14 and on the side walls and bottom surface of trench 18.
  • Trench 18, with barrier metal layer 16 extending downwardly therein, has a depth 20 similar to the thickness 22 of layer 14. For purposes of the present invention, the term trench means any type of depression or recess as known in the art, for example, a trench or a via. The trench also includes a width or diameter 24 which may be quite narrow. In particular, width 24 may be on the order of 0.13 μm or thereabout, and generally is in the range of less than 0.15 μm. Due to the narrow width of trench or via 18, a copper (Cu) film is not easily deposited on walls 26 and 28, and on bottom surface 30 of the trench. Moreover, prior art processing steps which desire to achieve good adhesion of the Cu film to the barrier metal layer, often result in poor gap filling characteristics of the Cu film in the trench or via.
  • FIG. 2 shows the IC device of FIG. 1 subjected to the pre-treatment rapid thermal process step, indicated by arrows 32. Arrows 32 represent the conditions of the RTP step which include subjecting barrier metal layer 16 to a non-reactive gas such as hydrogen gas (H2), argon (Ar), or helium (He), or to an ambient vacuum. The temperature range of the process typically is greater than 200 degrees Celsius, and preferably is between 250 and 550 degrees Celsius. The chamber pressure typically is between 0.1 mTorr and 20 Torr, and the RTP time typically is between 30 to 100 seconds. This pre-treatment process eliminates variations in the subsequently deposited Cu film which may be caused by Cu precursors. In other words, the RTP disclosed herein is insensitive to variations in precursor composition, volatility, and other precursor variables. After being subjected to the RTP process described above, barrier metal layer 16 is ready for the deposition of the copper film thereon.
  • FIG. 3 is a schematic of the copper deposition step of the process of the present invention. The Cu deposition step is represented by arrows 34. The deposition of the Cu film may be by physical vapor deposition (PVD), chemical vapor deposition (CVD), or any other known means of placing a copper film on a barrier metal layer. In the preferred embodiment, copper deposition step 34 comprises CVD in order to achieve a uniform and thin layer of copper material on pre-treated metal barrier layer 16′. The conditions of the CVD of Cu are well known in the art and will not be discussed herein.
  • FIG. 4 is a schematic of a copper layer 36 deposited on pre-treated barrier metal layer 16′ after the rapid thermal pre-treatment process step 32 described above. Performing the rapid thermal process step before the deposition of the Cu film results in a thin, shiny, densely nucleated, and adhesive Cu film 36 being deposited on a variety of barrier metal surfaces such as TiN or TaN. The copper film 36 is evenly distributed on layer 16, including throughout trench or via 18. In particular, Cu layer 36 is deposited in trench or via 18 so that the entire trench or via is filled with copper material and does not include key holes or other such variations in the copper layer. The adhesive Cu film 36 deposited on pre-treated barrier metal layer 16′ withstands traditional tape tests and does not flake or peel from pre-treated barrier metal layer 16′, as do the deposited Cu films of the prior art. Accordingly, the deposited Cu film has superior adhesive and trench filling characteristics compared to prior art Cu deposition processes. Moreover, the rapid thermal process step of the present invention has isotropic characteristics which is an advantage of this process in comparison to other surface treatments, such as plasma treatments. In particular, the rapid thermal process step 32 of the present invention results in better step coverage and trench fill. Accordingly, the process disclosed herein is an enabling technology for the use of metal organic CVD (MOCVD) Cu in the fabrication of IC devices.
  • FIG. 5 is a flow diagram of the process of the present invention. Step 50 comprises providing a partially processed integrated circuit (IC) device 10 including a substrate 12, a low dielectric constant (k) interlayer dielectric (ILD) layer 14 and a barrier metal layer 16 positioned thereon, wherein layer 16 typically includes one or more trenches or vias 18. The IC device is then subjected to the pre-treatment rapid thermal process step. The first step 52 of the pre-treatment process involves choosing the gas condition that will be utilized. The conditions of step 52 include subjecting barrier metal layer 16 to a non-reactive gas such as Hydrogen gas (H2), Argon (Ar), or Helium (He), or to an ambient vacuum. Step 54 includes choosing the temperature of the process, which typically is greater than 200 degrees Celsius, and preferably is between 250 and 550 degrees Celsius. Step 56 includes choosing the chamber pressure, which typically is between 0.1 mTorr and 20 Torr. Step 58 includes choosing the process time, which typically is between 30 to 100 seconds. Step 60 includes subjecting the IC device, and in particular barrier metal layer 16, to the vacuum/gas, temperature, and pressure chosen above, for the chosen time period. This pre-treatment process results in a pre-treated barrier metal layer, shown as layer 16′ in FIG. 4, which is ready for the deposition of a copper film thereon. Step 62 includes depositing a copper film on pre-treated barrier layer 16′ by process steps as known in the art. The deposition of the Cu film in step 62 may be by physical vapor deposition (PVD), chemical vapor deposition (CVD), or any other known means of placing a copper film on the pre-treated barrier metal layer. In a preferred embodiment, the Cu film is deposited by CVD due to its superior film application characteristics on barrier metal layers.
  • In a preferred embodiment, the deposition of the barrier layer on the substrate, the RTP treatment, and the deposition of the Cu film are all accomplished in-situ (without a vacuum break, but in different process chambers), thereby facilitating efficiency and cost effectiveness in the fabrication process. Of course, the steps may be undertaken ex-situ (with a vacuum break, and exposed to air), or in a combination of in-situ and ex-situ steps.
  • Thus, an improved IC device having a Cu film deposited thereon, and a rapid thermal pre-treatment process of manufacturing the same, has been disclosed. Although preferred structures and methods of manufacturing the device have been disclosed, it should be appreciated that further variations and modifications may be made thereto without departing from the scope of the invention as defined in the appended claims.

Claims (20)

1. A method of pre-treating a barrier metal layer of a partially finished integrated circuit device prior to the deposition of a copper film thereon, comprising the steps of:
providing a partially finished integrated circuit device including a barrier metal layer;
subjecting said barrier metal layer to a temperature greater than 200 degrees Celsius for at least thirty seconds to form a pre-treated barrier metal layer; and
depositing a copper film on said pre-treated barrier metal layer.
2. The method of claim 1 wherein said step of subjecting said barrier metal layer to a temperature comprises subjecting the barrier metal layer to a temperature in a range of 250 to 550 degrees Celsius.
3. The method of claim 1, prior to depositing said copper film on said pre-treated barrier metal layer, further comprising the step of subjecting said barrier metal layer to an atmosphere chosen from the group consisting of: an ambient vacuum, hydrogen gas, argon gas, and helium gas.
4. The method of claim 1, prior to depositing said copper film on said pre-treated barrier metal layer, further comprising the step of subjecting said barrier metal layer to a pressure in a range of 0.1 mTorr to 20 Torr.
5. The method of claim 1, wherein said barrier metal layer is subjected to a temperature greater than 200 degrees for 30 to 100 seconds.
6. The method of claim 1 wherein said barrier metal layer comprises a trench having a side wall, a bottom surface, and a width of 0.13 μm or less, and wherein said copper film is deposited by chemical vapor deposition throughout said trench and against said side wall and said bottom surface.
7. The method of claim 1 wherein said copper film deposited on said pre-treated barrier metal layer has adhesion properties such that said copper film remains adhered to said pre-treated barrier metal layer when said copper film is subjected to a tape test.
8. The method of claim 1 wherein said barrier metal layer is chosen from the group consisting of TiN and TaN.
9. A method of pre-treating a barrier metal layer of a partially finished integrated circuit device for the deposition of a copper film thereon, comprising the steps of:
providing a partially finished integrated circuit device including a barrier metal layer having a trench therein;
subjecting said barrier metal layer to a temperature greater than 200 degrees Celsius for at least thirty seconds in an atmosphere chosen from the group consisting of: an ambient vacuum, Hydrogen gas, Argon gas, and Helium gas to form a pre-treated barrier metal layer; and
thereafter depositing a copper film on said pre-treated barrier metal layer and throughout said trench.
10. The method of claim 9, simultaneous to subjecting said barrier metal layer to said atmosphere, further comprising the step of subjecting said barrier metal layer to a pressure in a range of 0.1 mTorr to 20 Torr.
11. The method of claim 9 wherein said trench has a width of 0.13 μm or less.
12. The method of claim 9 wherein said copper film deposited on said pre-treated barrier metal layer has adhesion properties such that said copper film remains adhered to said pre-treated barrier metal layer when said copper film is subjected to a tape test, and wherein said copper film has uniform properties there through.
13. An integrated circuit device manufactured by the method of claim 9.
14. An integrated circuit device manufactured by the process of:
providing a partially finished integrated circuit device including a barrier metal layer;
subjecting said barrier metal layer to a temperature greater than 200 degrees Celsius for at least thirty seconds; and
thereafter depositing a copper film on said barrier metal layer.
15. A integrated circuit according to claim 14, further manufactured by the process of, prior to depositing said copper film on said barrier metal layer, subjecting said barrier metal layer to a temperature in a range of 250 to 550 degrees Celsius.
16. A integrated circuit according to claim 14, further manufactured by the process of, prior to depositing said copper film on said barrier metal layer, subjecting said barrier metal layer to an atmosphere chosen from the group consisting of: an ambient vacuum, Hydrogen gas, Argon gas, and Helium gas.
17. A integrated circuit according to claim 14, further manufactured by the process of, prior to depositing said copper film on said barrier metal layer, subjecting said barrier metal layer to a pressure in a range of 0.1 mTorr to 20 Torr.
18. A integrated circuit according to claim 14, further manufactured by the process of, prior to depositing said copper film on said barrier metal layer, subjecting said barrier metal layer to a temperature greater than 200 degrees for 30 to 100 seconds.
19. A integrated circuit according to claim 14 wherein said barrier metal layer comprises a trench having a side wall, a bottom surface, and a width of 0.13 μm or less, and wherein said copper film is deposited throughout said trench.
20. A integrated circuit according to claim 14 wherein said copper film deposited on said metal barrier layer has adhesion properties such that said copper film remains adhered to said barrier metal layer when said copper film is subjected to a tape test and wherein said barrier metal layer is chosen from the group consisting of TiN and TaN.
US10/903,610 2001-03-28 2004-07-29 Integrated circuit having barrier metal surface treatment prior to Cu deposition Abandoned US20050003663A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US10/903,610 US20050003663A1 (en) 2001-03-28 2004-07-29 Integrated circuit having barrier metal surface treatment prior to Cu deposition

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US09/820,068 US6777327B2 (en) 2001-03-28 2001-03-28 Method of barrier metal surface treatment prior to Cu deposition to improve adhesion and trench filling characteristics
US10/903,610 US20050003663A1 (en) 2001-03-28 2004-07-29 Integrated circuit having barrier metal surface treatment prior to Cu deposition

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US09/820,068 Division US6777327B2 (en) 2001-03-28 2001-03-28 Method of barrier metal surface treatment prior to Cu deposition to improve adhesion and trench filling characteristics

Publications (1)

Publication Number Publication Date
US20050003663A1 true US20050003663A1 (en) 2005-01-06

Family

ID=25229802

Family Applications (2)

Application Number Title Priority Date Filing Date
US09/820,068 Expired - Fee Related US6777327B2 (en) 2001-03-28 2001-03-28 Method of barrier metal surface treatment prior to Cu deposition to improve adhesion and trench filling characteristics
US10/903,610 Abandoned US20050003663A1 (en) 2001-03-28 2004-07-29 Integrated circuit having barrier metal surface treatment prior to Cu deposition

Family Applications Before (1)

Application Number Title Priority Date Filing Date
US09/820,068 Expired - Fee Related US6777327B2 (en) 2001-03-28 2001-03-28 Method of barrier metal surface treatment prior to Cu deposition to improve adhesion and trench filling characteristics

Country Status (4)

Country Link
US (2) US6777327B2 (en)
JP (1) JP4127359B2 (en)
KR (1) KR100472259B1 (en)
TW (1) TWI223333B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050196945A1 (en) * 2004-03-05 2005-09-08 Jong-Ho Yun Methods of forming a double metal salicide layer and methods of fabricating semiconductor devices incorporating the same
CN102427046A (en) * 2011-11-30 2012-04-25 中国科学院微电子研究所 A method for determining the result of electrochemical deposition

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7335965B2 (en) 1999-08-25 2008-02-26 Micron Technology, Inc. Packaging of electronic chips with air-bridge structures
KR100465063B1 (en) * 2002-04-01 2005-01-06 주식회사 하이닉스반도체 Method for manufacturing metal interconnection layer of semiconductor device
US6949461B2 (en) * 2002-12-11 2005-09-27 International Business Machines Corporation Method for depositing a metal layer on a semiconductor interconnect structure
US7202562B2 (en) * 2004-12-02 2007-04-10 Micron Technology, Inc. Integrated circuit cooling system and method
US7927948B2 (en) 2005-07-20 2011-04-19 Micron Technology, Inc. Devices with nanocrystals and methods of formation
US7556840B2 (en) * 2006-06-30 2009-07-07 Caterpillar Inc. Coating using metal organic chemical vapor deposition
SG174750A1 (en) * 2006-08-30 2011-10-28 Lam Res Corp Controlled ambient system for interface engineering
US8916232B2 (en) * 2006-08-30 2014-12-23 Lam Research Corporation Method for barrier interface preparation of copper interconnect
KR100822555B1 (en) * 2006-10-31 2008-04-16 주식회사 하이닉스반도체 Metal wiring formation method of semiconductor device
KR100781456B1 (en) * 2006-11-24 2007-12-03 동부일렉트로닉스 주식회사 Barrier film formation method for manufacturing metal wiring of semiconductor device

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6184128B1 (en) * 2000-01-31 2001-02-06 Advanced Micro Devices, Inc. Method using a thin resist mask for dual damascene stop layer etch
US6455421B1 (en) * 2000-07-31 2002-09-24 Applied Materials, Inc. Plasma treatment of tantalum nitride compound films formed by chemical vapor deposition

Family Cites Families (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04259242A (en) * 1991-02-14 1992-09-14 Fujitsu Ltd Manufacture of semiconductor device
US5622608A (en) * 1994-05-05 1997-04-22 Research Foundation Of State University Of New York Process of making oxidation resistant high conductivity copper layers
US6251758B1 (en) * 1994-11-14 2001-06-26 Applied Materials, Inc. Construction of a film on a semiconductor wafer
US6291343B1 (en) * 1994-11-14 2001-09-18 Applied Materials, Inc. Plasma annealing of substrates to improve adhesion
US5989999A (en) * 1994-11-14 1999-11-23 Applied Materials, Inc. Construction of a tantalum nitride film on a semiconductor wafer
KR980005615A (en) * 1996-06-29 1998-03-30 김주용 METHOD FOR FORMING METAL WIRING OF SEMICONDUCTOR
US5851367A (en) * 1996-10-11 1998-12-22 Sharp Microelectronics Technology, Inc. Differential copper deposition on integrated circuit surfaces and method for same
JP3304807B2 (en) * 1997-03-13 2002-07-22 三菱電機株式会社 Copper thin film deposition method
JPH11150084A (en) * 1997-09-12 1999-06-02 Canon Inc Semiconductor device and method of forming amorphous titanium titanium nitride on substrate
US5939788A (en) * 1998-03-11 1999-08-17 Micron Technology, Inc. Copper diffusion barrier, aluminum wetting layer and improved methods for filling openings in silicon substrates with cooper
US6461675B2 (en) * 1998-07-10 2002-10-08 Cvc Products, Inc. Method for forming a copper film on a substrate
KR20000037885A (en) * 1998-12-02 2000-07-05 전주범 Fine pattern formation method
US6218256B1 (en) * 1999-04-13 2001-04-17 Micron Technology, Inc. Electrode and capacitor structure for a semiconductor device and associated methods of manufacture
KR100333712B1 (en) * 1999-06-24 2002-04-24 박종섭 A method for forming damascene type metal wire in semiconductor device
US6177347B1 (en) * 1999-07-02 2001-01-23 Taiwan Semiconductor Manufacturing Company In-situ cleaning process for Cu metallization
US6534404B1 (en) * 1999-11-24 2003-03-18 Novellus Systems, Inc. Method of depositing diffusion barrier for copper interconnect in integrated circuit
US6567541B1 (en) * 2000-02-25 2003-05-20 Ahbee 1, L.P. Method and apparatus for adhesion testing of thin film materials
US6548395B1 (en) * 2000-11-16 2003-04-15 Advanced Micro Devices, Inc. Method of promoting void free copper interconnects
JP4300259B2 (en) * 2001-01-22 2009-07-22 キヤノンアネルバ株式会社 Copper wiring film forming method
TW471134B (en) * 2001-02-27 2002-01-01 United Microelectronics Corp Manufacturing method for multilevel interconnects
US6509266B1 (en) * 2001-04-02 2003-01-21 Air Products And Chemicals, Inc. Halogen addition for improved adhesion of CVD copper to barrier

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6184128B1 (en) * 2000-01-31 2001-02-06 Advanced Micro Devices, Inc. Method using a thin resist mask for dual damascene stop layer etch
US6455421B1 (en) * 2000-07-31 2002-09-24 Applied Materials, Inc. Plasma treatment of tantalum nitride compound films formed by chemical vapor deposition

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050196945A1 (en) * 2004-03-05 2005-09-08 Jong-Ho Yun Methods of forming a double metal salicide layer and methods of fabricating semiconductor devices incorporating the same
US7238612B2 (en) * 2004-03-05 2007-07-03 Samsung Electronics Co., Ltd. Methods of forming a double metal salicide layer and methods of fabricating semiconductor devices incorporating the same
US20070224765A1 (en) * 2004-03-05 2007-09-27 Samsung Electronics Co. Ltd. Methods of fabricating semiconductor devices having a double metal salicide layer
US7666786B2 (en) 2004-03-05 2010-02-23 Samsung Electronics Co., Ltd. Methods of fabricating semiconductor devices having a double metal salicide layer
CN102427046A (en) * 2011-11-30 2012-04-25 中国科学院微电子研究所 A method for determining the result of electrochemical deposition

Also Published As

Publication number Publication date
TWI223333B (en) 2004-11-01
KR100472259B1 (en) 2005-03-08
JP2002334877A (en) 2002-11-22
KR20020077170A (en) 2002-10-11
US6777327B2 (en) 2004-08-17
JP4127359B2 (en) 2008-07-30
US20020142590A1 (en) 2002-10-03

Similar Documents

Publication Publication Date Title
US6207557B1 (en) Method of forming multilayer titanium nitride film by multiple step chemical vapor deposition process and method of manufacturing semiconductor device using the same
US7785658B2 (en) Method for forming metal wiring structure
US5972179A (en) Silicon IC contacts using composite TiN barrier layer
US8278205B2 (en) Semiconductor device and method for manufacturing the same
US20030091870A1 (en) Method of forming a liner for tungsten plugs
US7145241B2 (en) Semiconductor device having a multilayer interconnection structure and fabrication process thereof
US6777327B2 (en) Method of barrier metal surface treatment prior to Cu deposition to improve adhesion and trench filling characteristics
US5895267A (en) Method to obtain a low resistivity and conformity chemical vapor deposition titanium film
US20030157781A1 (en) Method of filling trenches
US6673718B1 (en) Methods for forming aluminum metal wirings
KR100289515B1 (en) Barrier emtal layer and method of forming the same
KR20050022526A (en) Semiconductor Device And Method For Manufacturing The Same
KR100465093B1 (en) Method For Manufacturing Semiconductor Devices
US7338903B2 (en) Sequential reducing plasma and inert plasma pre-treatment method for oxidizable conductor layer
CN1326206C (en) Method of manufacturing an electronic device
US7846839B2 (en) Film forming method, semiconductor device manufacturing method, semiconductor device, program and recording medium
JP3490317B2 (en) Copper thin film formation by chemical vapor deposition
KR100685902B1 (en) Metal wiring of semiconductor device and manufacturing method thereof
US20090261477A1 (en) Semiconductor device and method of manufacturing the same
JPH1074709A (en) Semiconductor device and its manufacture
US6509268B1 (en) Thermal densification in the early stages of copper MOCVD for depositing high quality Cu films with good adhesion and trench filling characteristics
KR20010048188A (en) Tungsten Plug Forming Method
JP2002033322A (en) Method for manufacturing semiconductor device
JP2003224125A (en) Method for manufacturing semiconductor device
KR20030052806A (en) Method For Manufacturing Semiconductor Devices

Legal Events

Date Code Title Description
STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION