EP2661515A1 - Filament for hot wire chemical vapour deposition - Google Patents

Filament for hot wire chemical vapour deposition

Info

Publication number
EP2661515A1
EP2661515A1 EP12701685.5A EP12701685A EP2661515A1 EP 2661515 A1 EP2661515 A1 EP 2661515A1 EP 12701685 A EP12701685 A EP 12701685A EP 2661515 A1 EP2661515 A1 EP 2661515A1
Authority
EP
European Patent Office
Prior art keywords
filament
coating
ceramic
filament according
vapour deposition
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.)
Withdrawn
Application number
EP12701685.5A
Other languages
German (de)
French (fr)
Inventor
Antulio Tarazona Labrador
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.)
Echerkon Technologies Ltd
Original Assignee
Echerkon Technologies Ltd
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 Echerkon Technologies Ltd filed Critical Echerkon Technologies Ltd
Priority to EP12701685.5A priority Critical patent/EP2661515A1/en
Publication of EP2661515A1 publication Critical patent/EP2661515A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • C23C16/448—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for generating reactive gas streams, e.g. by evaporation or sublimation of precursor materials
    • C23C16/4488—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for generating reactive gas streams, e.g. by evaporation or sublimation of precursor materials by in situ generation of reactive gas by chemical or electrochemical reaction

Definitions

  • the invention refers to a filament for hot wire chemical vapour deposition of semiconductor layers, especially silicon layers, or dielectric layers.
  • the invention also refers to a method for making such a filament and its use for deposition of silicon or carbon containing layers by hot wire chemical vapour deposition.
  • hot wire chemical vapour deposition HWCVD
  • HWCVD hot wire chemical vapour deposition
  • CAT-CVD or Hot Filament CVD heated catalytic filaments made of catalysts like tungsten, tantalum, molybdenum or other refractory metals are used to catalytically convert precursor molecules into radicals which form semiconductor or dielectric layers.
  • precursor molecules silane molecules used to grow silicon layers.
  • germanium hydrides which may be used to deposit germanium layers, carbon hydrides for deposition of diamond like layers or mixtures of ammonia and silane molecules for silicon nitride layers.
  • HWCVD promises very high deposition rates of thin film layers and is easily scaleable up to very large areas.
  • catalytic filaments tend to age rather quickly due to formation of silicides or carbides, depending on the type of precursor molecules employed. Thereby filaments become increasingly brittle which eventually leads to breakage.
  • Irreversible silicide formation is temperature dependent and most pronounced at temperatures significantly between 1600 °C to 1900 °C.
  • the ends of a catalytic filament have cold spots, at temperatures where irreversible silicide or carbide formation takes place, due to the contact to voltage source terminals, which have a high thermal mass, and therefore have a lower temperature.
  • the object of the present invention is therefore to show a way to improve the lifetime of refractory metal filaments used in HWCVD, especially for the deposition of silicon layers.
  • the coating encapsulates the catalytic filament, protecting it from the precursor molecules. This prevents the formation of silicides or carbides, which leads to a significant increase in the lifetime of the filament.
  • the coating may be a ceramic coating, preferably made of a non-silicide ceramic, e.g. a ceramic coating based on zirconia, alumina, silicon carbide, boron nitride or silicon nitride.
  • a silicide ceramic is a compound of a metal and silicon.
  • at least two spaced apart sections of the filament are provided with a temperature resistant coating. That means that a section between the coated sections is uncoated and therefore has a catalytic metal surface exposed to precursor molecules.
  • Refractory metals are Nb, Mo, Ta, W and Re.
  • a refractory metal filament may there be made of these elements or an alloy consisting predominantly, i.e. more than 50 % by weight, of these elements.
  • Ceramic coatings consisting of ceramic material that is made of elements that have a lower atomic number than the predominant constituent of the refrac- tory metal are preferred.
  • the elements of which the ceramic material is made preferably have a atomic number of 40 or less.
  • the coating may be applied as a suspension of ceramic or carbon particles.
  • a mixture of a binder and ceramic or carbon particles can be easily ap- plied to a wire, e.g. by painting.
  • resins or water may be used as binders.
  • Figure 1 shows schematically an exemplary embodiment of a clamping arrangement according to the present invention
  • the filament arrangement shown schematically in a cross-section view by figure 1 comprises a clamping mechanism 1 which maintains tension and provides electrical contacts of a refractory metal filament 2 for catalytic conversion of precursor molecules like silane.
  • the coldest exposed parts of the filament are closest to the clamping mechanism and voltage source, and are encapsulated 3.
  • the catalytic filament 2 can be made out of tungsten, tantalum, molybdenum, niobium or an alloy of these metals. Tungsten, tantalum and/or molybdenum may also be alloyed with a noble metal.
  • the filament 2 preferably has a di- ameter of 0.1 mm to 1 mm.
  • the coating material should be made of ultra-high temperature coating able to withstand temperatures in excess of 1900 °C.
  • These coatings are typically composed of zirconia, alumina, silicon carbide, boron nitride, sili- con nitride, carbon or composites of these materials.
  • ResbondTM 904 and its thinner could be used, whereas carbon coating could be produced using a saturated Polyacrylonitrile (PAN) in dimethyl formamide (DMF) solution or graphite colloidal solutions. More than one type of the materials described above can be applied subsequently.
  • PAN Polyacrylonitrile
  • DMF dimethyl formamide
  • the coating is applied as a suspension, e.g. in a paste or paint form, which may be mixed with a suitable thinner or solvent to ensure a thin and even coating of the filament. Only a thin coating is required to protect the catalytic filament from the precursor gases while minimising the thermal mass of the coating.
  • At least one filament arrangement is placed in a chamber which is then evacuated below atmos- pheric pressure. By installing several such filaments in the chamber deposition rates and uniformity can be favourably increased.
  • the filaments 2 are then heated up to temperatures above 1900°C by passing an electric current through them.
  • Gas precursors or vapours containing precursor molecules are then introduced in the chamber and broken down by the exposed hot catalytic filament 2 which thereby converts the precursor molecules catalytically into radicals.
  • precursor molecules encompasses for instance mono-, di- and tri- silane molecules as well as any other hydrides of silicon used as precursors to deposit thin films of silicon.
  • gases or precursors can be added to modify the characteristics of the film, e.g. doping. For example ammonia may be added to grow silicon nitride films.
  • germanium hydride molecules For deposition of other semiconductor layers, for example germanium or sil- con/germanium films, germanium hydride molecules have to be used as pre- cursors. Likewise carbon hydride molecules may be used to grow diamond like film by HWCVD.

Landscapes

  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Electrochemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Vapour Deposition (AREA)
  • Inorganic Fibers (AREA)

Abstract

The invention refers to a refractory metal filament for hot wire chemical vapour deposition of semiconductor or dielectric layers, characterized in that at least two spaced apart sections of the filament are provided with a temperature resistant coating. The invention also refers to a method for making such a filament and its use for hot wire chemical vapour deposition of semiconductor or dielectric layers.

Description

Filament for Hot Wire Chemical Vapour Deposition
The invention refers to a filament for hot wire chemical vapour deposition of semiconductor layers, especially silicon layers, or dielectric layers. The invention also refers to a method for making such a filament and its use for deposition of silicon or carbon containing layers by hot wire chemical vapour deposition. In the so called hot wire chemical vapour deposition (HWCVD), also know as
CAT-CVD or Hot Filament CVD, heated catalytic filaments made of catalysts like tungsten, tantalum, molybdenum or other refractory metals are used to catalytically convert precursor molecules into radicals which form semiconductor or dielectric layers. One of the most widely researched precursor molecules are silane molecules used to grow silicon layers. Other possible precursor molecules are germanium hydrides which may be used to deposit germanium layers, carbon hydrides for deposition of diamond like layers or mixtures of ammonia and silane molecules for silicon nitride layers. HWCVD promises very high deposition rates of thin film layers and is easily scaleable up to very large areas. However, catalytic filaments tend to age rather quickly due to formation of silicides or carbides, depending on the type of precursor molecules employed. Thereby filaments become increasingly brittle which eventually leads to breakage.
Irreversible silicide formation is temperature dependent and most pronounced at temperatures significantly between 1600 °C to 1900 °C. In prior art the ends of a catalytic filament have cold spots, at temperatures where irreversible silicide or carbide formation takes place, due to the contact to voltage source terminals, which have a high thermal mass, and therefore have a lower temperature. The object of the present invention is therefore to show a way to improve the lifetime of refractory metal filaments used in HWCVD, especially for the deposition of silicon layers.
This object is achieved by coating the cold spots of the filaments with a high temperature resistant material. The coating encapsulates the catalytic filament, protecting it from the precursor molecules. This prevents the formation of silicides or carbides, which leads to a significant increase in the lifetime of the filament. The coating may be a ceramic coating, preferably made of a non-silicide ceramic, e.g. a ceramic coating based on zirconia, alumina, silicon carbide, boron nitride or silicon nitride. A silicide ceramic is a compound of a metal and silicon. According to the present invention, at least two spaced apart sections of the filament are provided with a temperature resistant coating. That means that a section between the coated sections is uncoated and therefore has a catalytic metal surface exposed to precursor molecules.
Refractory metals are Nb, Mo, Ta, W and Re. A refractory metal filament may there be made of these elements or an alloy consisting predominantly, i.e. more than 50 % by weight, of these elements.
Ceramic coatings consisting of ceramic material that is made of elements that have a lower atomic number than the predominant constituent of the refrac- tory metal are preferred. The elements of which the ceramic material is made preferably have a atomic number of 40 or less.
The coating may be applied as a suspension of ceramic or carbon particles. Such a mixture of a binder and ceramic or carbon particles can be easily ap- plied to a wire, e.g. by painting. For example, resins or water may be used as binders.
Further aspects and advantages of the present invention are explained in the following with respect to the enclosed figure illustrating a preferred embodi- ment of the invention.
Figure 1 shows schematically an exemplary embodiment of a clamping arrangement according to the present invention; The filament arrangement shown schematically in a cross-section view by figure 1 comprises a clamping mechanism 1 which maintains tension and provides electrical contacts of a refractory metal filament 2 for catalytic conversion of precursor molecules like silane. The coldest exposed parts of the filament are closest to the clamping mechanism and voltage source, and are encapsulated 3. For deposition of semiconductor films like silicon films or dielectric films, the catalytic filament 2 can be made out of tungsten, tantalum, molybdenum, niobium or an alloy of these metals. Tungsten, tantalum and/or molybdenum may also be alloyed with a noble metal. The filament 2 preferably has a di- ameter of 0.1 mm to 1 mm.
Preferably the coating material should be made of ultra-high temperature coating able to withstand temperatures in excess of 1900 °C. These coatings are typically composed of zirconia, alumina, silicon carbide, boron nitride, sili- con nitride, carbon or composites of these materials. For the zirconia coating Resbond™ 904 and its thinner could be used, whereas carbon coating could be produced using a saturated Polyacrylonitrile (PAN) in dimethyl formamide (DMF) solution or graphite colloidal solutions. More than one type of the materials described above can be applied subsequently. Anyone familiar in the art would immediately understand the benefits of applying such coatings.
Preferably the coating is applied as a suspension, e.g. in a paste or paint form, which may be mixed with a suitable thinner or solvent to ensure a thin and even coating of the filament. Only a thin coating is required to protect the catalytic filament from the precursor gases while minimising the thermal mass of the coating.
In order to deposit silicon layers onto a substrate, at least one filament arrangement is placed in a chamber which is then evacuated below atmos- pheric pressure. By installing several such filaments in the chamber deposition rates and uniformity can be favourably increased. The filaments 2 are then heated up to temperatures above 1900°C by passing an electric current through them. Gas precursors or vapours containing precursor molecules are then introduced in the chamber and broken down by the exposed hot catalytic filament 2 which thereby converts the precursor molecules catalytically into radicals. The term precursor molecules encompasses for instance mono-, di- and tri- silane molecules as well as any other hydrides of silicon used as precursors to deposit thin films of silicon. Other gases or precursors can be added to modify the characteristics of the film, e.g. doping. For example ammonia may be added to grow silicon nitride films.
For deposition of other semiconductor layers, for example germanium or sil- con/germanium films, germanium hydride molecules have to be used as pre- cursors. Likewise carbon hydride molecules may be used to grow diamond like film by HWCVD.

Claims

Claims
Refractory metal filament for hot wire chemical vapour deposition of semiconductor or dielectric layers, characterized in that at least two spaced apart sections of the filament are provided with a temperature resistant coating.
Filament according to claim 1, characterized in that the coating is a non-metallic coating.
Filament according to any of the preceding claims, characterized in that the coating is a ceramic or carbon coating.
Filament according to any of the preceding claims, characterized in that the coating is made of a crystalline ceramic material.
Filament according to claim 4, characterized in that the ceramic material is a non-silicide ceramic.
Filament according to claim 4 or 5, characterized in that the ceramic material is made of elements that have a lower atomic number than the predominant constituent of the refractory metal.
Filament according to any of the preceding claims, characterized in that the coating is applied as a suspension containing carbon particles and/or ceramic particles.
Filament according to any of the preceding claims, characterized in that the sections of filament are between 1mm and 70mm in length.
Filament according to any of the preceding claims, characterized in that the metal filament consists predominantly of tungsten, tantalum and/or molybdenum.
10. Filament according to any of the preceding claims, characterized in that the coating consists predominantly zirconia, alumina, silicon carbide, boron nitride, graphite and/or silicon nitride.
11. Filament according to any of the preceding claims, characterized in that the coating is temperature resistant up at least 1900°C, preferably at least 2000°C, in a reductive atmosphere.
12. Filament according to any of the preceding claims, characterized in that two end sections of the wire are provided with a temperature resistant coating.
13. Use of a filament according to any of the preceding claims for hot wire chemical vapour deposition of semiconductor or dielectric lay- ers.
14. Method for making a filament for hot wire chemical vapour deposition of semiconductor or dielectric layers, said method comprising the following steps :
providing a refractory metal wire, characterized by coating at least to sections of the filament with a suspension of ceramic or carbon particles.
15. Method according to claim 14, characterized in that the suspension is a mixture of a resin and ceramic or carbon particles.
16. Method according to claim 15, characterized in that the suspension is a mixture of water and ceramic or carbon particles.
EP12701685.5A 2011-01-04 2012-01-04 Filament for hot wire chemical vapour deposition Withdrawn EP2661515A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP12701685.5A EP2661515A1 (en) 2011-01-04 2012-01-04 Filament for hot wire chemical vapour deposition

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP11150048 2011-01-04
EP12701685.5A EP2661515A1 (en) 2011-01-04 2012-01-04 Filament for hot wire chemical vapour deposition
PCT/EP2012/050100 WO2012093142A1 (en) 2011-01-04 2012-01-04 Filament for hot wire chemical vapour deposition

Publications (1)

Publication Number Publication Date
EP2661515A1 true EP2661515A1 (en) 2013-11-13

Family

ID=45401019

Family Applications (1)

Application Number Title Priority Date Filing Date
EP12701685.5A Withdrawn EP2661515A1 (en) 2011-01-04 2012-01-04 Filament for hot wire chemical vapour deposition

Country Status (3)

Country Link
EP (1) EP2661515A1 (en)
CN (1) CN103339286A (en)
WO (1) WO2012093142A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SG11201706481RA (en) * 2015-02-18 2017-09-28 Kirin Co Ltd Heat generation element and method for producing same

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003247062A (en) * 2002-02-26 2003-09-05 Sony Corp Method and apparatus for depositing thin film
JP3861178B2 (en) * 2002-08-30 2006-12-20 広島県 Hot filament CVD method
KR20110084520A (en) * 2008-12-09 2011-07-25 가부시키가이샤 아루박 Catalyst chemical vapor deposition apparatus

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2012093142A1 *

Also Published As

Publication number Publication date
CN103339286A (en) 2013-10-02
WO2012093142A1 (en) 2012-07-12

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