CN111162006B - 处理方法和基板处理装置 - Google Patents

处理方法和基板处理装置 Download PDF

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Publication number
CN111162006B
CN111162006B CN201911082523.4A CN201911082523A CN111162006B CN 111162006 B CN111162006 B CN 111162006B CN 201911082523 A CN201911082523 A CN 201911082523A CN 111162006 B CN111162006 B CN 111162006B
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gas
hole
taper angle
deposit
substrate
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Chinese (zh)
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CN111162006A (zh
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吉村正太
伊藤清仁
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Tokyo Electron Ltd
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Tokyo Electron Ltd
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W20/00—Interconnections in chips, wafers or substrates
    • H10W20/01—Manufacture or treatment
    • H10W20/071—Manufacture or treatment of dielectric parts thereof
    • H10W20/081—Manufacture or treatment of dielectric parts thereof by forming openings in the dielectric parts
    • H10W20/084—Manufacture or treatment of dielectric parts thereof by forming openings in the dielectric parts for dual-damascene structures
    • H10W20/087—Manufacture or treatment of dielectric parts thereof by forming openings in the dielectric parts for dual-damascene structures involving multiple stacked pre-patterned masks
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P76/00—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography
    • H10P76/20—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography of masks comprising organic materials
    • H10P76/204—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography of masks comprising organic materials of organic photoresist masks
    • 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
    • C23C16/04—Coating on selected surface areas, e.g. using masks
    • C23C16/042—Coating on selected surface areas, e.g. using masks using masks
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
    • 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
    • C23C16/56—After-treatment
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
    • H10P14/60—Formation of materials, e.g. in the shape of layers or pillars of insulating materials
    • H10P14/63—Formation of materials, e.g. in the shape of layers or pillars of insulating materials characterised by the formation processes
    • H10P14/6326—Deposition processes
    • H10P14/6328—Deposition from the gas or vapour phase
    • H10P14/6334—Deposition from the gas or vapour phase using decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition
    • H10P14/6336—Deposition from the gas or vapour phase using decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition in the presence of a plasma [PECVD]
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
    • H10P14/60—Formation of materials, e.g. in the shape of layers or pillars of insulating materials
    • H10P14/68—Organic materials, e.g. photoresists
    • H10P14/683—Organic materials, e.g. photoresists carbon-based polymeric organic materials, e.g. polyimides, poly cyclobutene or PVC
    • H10P14/687—Organic materials, e.g. photoresists carbon-based polymeric organic materials, e.g. polyimides, poly cyclobutene or PVC the materials being fluorocarbon compounds, e.g. (CHxFy) n or polytetrafluoroethylene
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
    • H10P14/60—Formation of materials, e.g. in the shape of layers or pillars of insulating materials
    • H10P14/69—Inorganic materials
    • H10P14/6902—Inorganic materials composed of carbon, e.g. alpha-C, diamond or hydrogen doped carbon
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P50/00—Etching of wafers, substrates or parts of devices
    • H10P50/20—Dry etching; Plasma etching; Reactive-ion etching
    • H10P50/24—Dry etching; Plasma etching; Reactive-ion etching of semiconductor materials
    • H10P50/242—Dry etching; Plasma etching; Reactive-ion etching of semiconductor materials of Group IV materials
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P50/00—Etching of wafers, substrates or parts of devices
    • H10P50/20—Dry etching; Plasma etching; Reactive-ion etching
    • H10P50/28—Dry etching; Plasma etching; Reactive-ion etching of insulating materials
    • H10P50/282—Dry etching; Plasma etching; Reactive-ion etching of insulating materials of inorganic materials
    • H10P50/283—Dry etching; Plasma etching; Reactive-ion etching of insulating materials of inorganic materials by chemical means
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P50/00—Etching of wafers, substrates or parts of devices
    • H10P50/69—Etching of wafers, substrates or parts of devices using masks for semiconductor materials
    • H10P50/691—Etching of wafers, substrates or parts of devices using masks for semiconductor materials for Group V materials or Group III-V materials
    • H10P50/693—Etching of wafers, substrates or parts of devices using masks for semiconductor materials for Group V materials or Group III-V materials characterised by their size, orientation, disposition, behaviour or shape, in horizontal or vertical plane
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P50/00—Etching of wafers, substrates or parts of devices
    • H10P50/73—Etching of wafers, substrates or parts of devices using masks for insulating materials
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
    • H10P72/04—Apparatus for manufacture or treatment
    • H10P72/0451—Apparatus for manufacturing or treating in a plurality of work-stations
    • H10P72/0468—Apparatus for manufacturing or treating in a plurality of work-stations comprising a chamber adapted to a particular process
    • H10P72/0471—Apparatus for manufacturing or treating in a plurality of work-stations comprising a chamber adapted to a particular process comprising at least one ion or electron beam chamber
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P76/00—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography
    • H10P76/40—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography of masks comprising inorganic materials
    • H10P76/408—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography of masks comprising inorganic materials characterised by their sizes, orientations, dispositions, behaviours or shapes
    • H10P76/4085—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography of masks comprising inorganic materials characterised by their sizes, orientations, dispositions, behaviours or shapes characterised by the processes involved to create the masks
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W20/00—Interconnections in chips, wafers or substrates
    • H10W20/01—Manufacture or treatment
    • H10W20/071—Manufacture or treatment of dielectric parts thereof
    • H10W20/081—Manufacture or treatment of dielectric parts thereof by forming openings in the dielectric parts
    • H10W20/082—Manufacture or treatment of dielectric parts thereof by forming openings in the dielectric parts the openings being tapered via holes
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W20/00—Interconnections in chips, wafers or substrates
    • H10W20/01—Manufacture or treatment
    • H10W20/071—Manufacture or treatment of dielectric parts thereof
    • H10W20/081—Manufacture or treatment of dielectric parts thereof by forming openings in the dielectric parts
    • H10W20/084—Manufacture or treatment of dielectric parts thereof by forming openings in the dielectric parts for dual-damascene structures
    • H10W20/086—Manufacture or treatment of dielectric parts thereof by forming openings in the dielectric parts for dual-damascene structures involving buried masks
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W20/00—Interconnections in chips, wafers or substrates
    • H10W20/01—Manufacture or treatment
    • H10W20/071—Manufacture or treatment of dielectric parts thereof
    • H10W20/081—Manufacture or treatment of dielectric parts thereof by forming openings in the dielectric parts
    • H10W20/089—Manufacture or treatment of dielectric parts thereof by forming openings in the dielectric parts using processes for implementing desired shapes or dispositions of the openings, e.g. double patterning
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W20/00—Interconnections in chips, wafers or substrates
    • H10W20/01—Manufacture or treatment
    • H10W20/071—Manufacture or treatment of dielectric parts thereof
    • H10W20/093—Manufacture or treatment of dielectric parts thereof by modifying materials of the dielectric parts
    • H10W20/097—Manufacture or treatment of dielectric parts thereof by modifying materials of the dielectric parts by thermally treating

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Drying Of Semiconductors (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
CN201911082523.4A 2018-11-07 2019-11-07 处理方法和基板处理装置 Active CN111162006B (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2018210072A JP7195113B2 (ja) 2018-11-07 2018-11-07 処理方法及び基板処理装置
JP2018-210072 2018-11-07

Publications (2)

Publication Number Publication Date
CN111162006A CN111162006A (zh) 2020-05-15
CN111162006B true CN111162006B (zh) 2024-07-30

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US (1) US11380545B2 (https=)
JP (1) JP7195113B2 (https=)
KR (1) KR102944094B1 (https=)
CN (1) CN111162006B (https=)
TW (1) TWI826563B (https=)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10727045B2 (en) * 2017-09-29 2020-07-28 Taiwan Semiconductor Manufacturing Company, Ltd. Method for manufacturing a semiconductor device
JP7627645B2 (ja) * 2021-11-01 2025-02-06 東京エレクトロン株式会社 プラズマ処理方法及びプラズマ処理装置
JPWO2024203220A1 (https=) * 2023-03-24 2024-10-03

Family Cites Families (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6624016B2 (en) * 2001-02-22 2003-09-23 Silicon-Based Technology Corporation Method of fabricating trench isolation structures with extended buffer spacers
JP4176365B2 (ja) * 2002-03-25 2008-11-05 東京エレクトロン株式会社 プラズマエッチング方法
JP4727171B2 (ja) * 2003-09-29 2011-07-20 東京エレクトロン株式会社 エッチング方法
KR100553839B1 (ko) * 2003-11-27 2006-02-24 삼성전자주식회사 캐패시터와 그 제조 방법, 이를 포함하는 반도체 장치 및그 제조 방법
KR100573827B1 (ko) * 2003-12-30 2006-04-26 주식회사 하이닉스반도체 반도체 소자의 콘택 형성 방법
JP2006203035A (ja) * 2005-01-21 2006-08-03 Tokyo Electron Ltd プラズマエッチング方法
US7271108B2 (en) * 2005-06-28 2007-09-18 Lam Research Corporation Multiple mask process with etch mask stack
US20070181530A1 (en) * 2006-02-08 2007-08-09 Lam Research Corporation Reducing line edge roughness
JP2007294905A (ja) * 2006-03-30 2007-11-08 Hitachi High-Technologies Corp 半導体製造方法およびエッチングシステム
US7491343B2 (en) 2006-09-14 2009-02-17 Lam Research Corporation Line end shortening reduction during etch
US7894927B2 (en) * 2008-08-06 2011-02-22 Tokyo Electron Limited Using Multi-Layer/Multi-Input/Multi-Output (MLMIMO) models for metal-gate structures
US7772122B2 (en) * 2008-09-18 2010-08-10 Lam Research Corporation Sidewall forming processes
US8592327B2 (en) * 2012-03-07 2013-11-26 Tokyo Electron Limited Formation of SiOCl-containing layer on exposed low-k surfaces to reduce low-k damage
US20130267097A1 (en) * 2012-04-05 2013-10-10 Lam Research Corporation Method and apparatus for forming features with plasma pre-etch treatment on photoresist
JP2014225501A (ja) * 2013-05-15 2014-12-04 東京エレクトロン株式会社 プラズマエッチング方法及びプラズマエッチング装置
JP6185305B2 (ja) * 2013-06-28 2017-08-23 東京エレクトロン株式会社 プラズマエッチング方法およびプラズマエッチング装置
KR20150015978A (ko) * 2013-08-02 2015-02-11 삼성디스플레이 주식회사 표시 장치의 방법
CN104916577B (zh) * 2014-03-14 2018-08-24 北京北方华创微电子装备有限公司 斜孔刻蚀方法
US9922839B2 (en) 2015-06-23 2018-03-20 Lam Research Corporation Low roughness EUV lithography
JP2017084938A (ja) * 2015-10-27 2017-05-18 東京エレクトロン株式会社 被処理体を処理する方法

Also Published As

Publication number Publication date
US11380545B2 (en) 2022-07-05
US20200144051A1 (en) 2020-05-07
KR102944094B1 (ko) 2026-03-25
JP2020077753A (ja) 2020-05-21
JP7195113B2 (ja) 2022-12-23
TWI826563B (zh) 2023-12-21
CN111162006A (zh) 2020-05-15
TW202022928A (zh) 2020-06-16
KR20200052844A (ko) 2020-05-15

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