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
  • H01L21/02104—Forming layers
  • H01L21/02697—Forming conducting materials on a substrate
• • 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
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
  • C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
  • C23C18/1204—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material inorganic material, e.g. non-oxide and non-metallic such as sulfides, nitrides based compounds
  • C23C18/1208—Oxides, e.g. ceramics
  • C23C18/1216—Metal oxides
• • 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
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
  • C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
  • C23C18/125—Process of deposition of the inorganic material
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K2102/00—Constructional details relating to the organic devices covered by this subclass
  • H10K2102/10—Transparent electrodes, e.g. using graphene
  • H10K2102/101—Transparent electrodes, e.g. using graphene comprising transparent conductive oxides [TCO]
  • H10K2102/103—Transparent electrodes, e.g. using graphene comprising transparent conductive oxides [TCO] comprising indium oxides, e.g. ITO

Definitions

• the present invention relates to processes for the preparation of semiconductive indium oxide layers, to indium oxide layers which can be prepared by the process according to the invention and to their use.
• Indium oxide indium (III) oxide, In 2 Os
• Indium (III) oxide, In 2 Os is between 3.6 and 3.75 eV (measured for evaporated layers) due to the large band gap [HS Kim, PD Byrne, A. Facchetti, TJ. Marks; J. Am.
• Chem. Soc. 2008, 130, 12580-12581] is a promising semiconductor.
• thin films of a few hundred nanometers in thickness can have a high transparency in the visible spectral range of greater than 90% at 550 nm.
• charge carrier mobilities of up to 160 cm 2 A / s. So far, however, such values can not be reached by solution processing [H. Nakazawa, Y. Ito, E. Matsumoto, K. Adachi, N. Aoki, Y. Ochiai; J. Appl. Phys. 2006, 100, 093706. and A. Gupta, H. Cao, Parekh, KKV Rao, AR Raju, UV Waghmare; J. Appl. Phys. 2007, 101, 09N513].
• Indium oxide is often used together with tin (IV) oxide (SnO 2 ) as semiconducting mixed oxide ITO. Due to the relatively high conductivity of ITO layers with simultaneous transparency in the visible spectral range, it is used, inter alia, in the field of liquid crystal displays (LCDs), in particular as “transparent electrodes.” These mostly doped metal oxide layers are industrially predominantly through Due to the great economic interest in ITO-coated substrates, there are now a number of coating processes based on sol-gel techniques for indium oxide-containing layers.
• indium oxide semiconductors there are two possibilities for the production of indium oxide semiconductors via printing processes: 1) particle concepts in which (nano) particles are present in printable dispersion and are converted by sintering processes into the desired semiconductor layer after the printing process, and 2) precursor concepts in which at least one soluble precursor is converted to an indium oxide-containing layer after printing.
• the particle concept has two significant disadvantages compared to the use of precursors. Firstly, the particle dispersions have a colloidal instability which necessitates the use of dispersing additives (which are detrimental to the later layer properties) and, secondly Many of the usable particles (eg due to passivation layers) only incompletely form layers by sintering, so that partially particulate structures still occur in the layers. At the particle boundary there is a considerable particle-particle resistance, which reduces the mobility of the charge carriers and increases the general sheet resistance.
• indium oxide layers There are different precursors for the production of indium oxide layers.
• indium salts e.g. Indium alkoxides are used as precursors for the production of indium oxide-containing layers.
• indium alkoxide solutions offer the advantage that they can be converted to indium oxide-containing coatings at lower temperatures.
• Bradley et al. report a similar reaction as Mehrotra et al. and obtained at approximately identical reactants (InCl 3 , isopropyl-Nathum) and reaction conditions an indium oxo cluster with oxygen as the central atom [DC Bradley, H. Chudzynska, DM Frigo, ME Hammond, MB Hursthouse, MA Mazid; Polyhedron 1990, 9, 719].
• JP 11-106934 A (Fuji Photo Film Co. Ltd.) describes a method for producing a transparent conductive metal oxide film on a transparent substrate via a sol-gel process, wherein below 0 0 C, a metal alkoxide or a metal salt, preferably an indium alkoxide or indium salt, is hydrolyzed in solution and then the hydrolyzate is heated.
• JP 06-136162 A (Fujimori Kogyo KK) describes a process for producing a metal oxide film from solution on a substrate, in which a metal-alkoxide solution, in particular an indium-isopropoxide solution, is converted into a metal oxide gel , is applied to a substrate, dried and treated with heat, wherein before, during or after the drying and heat treatment step is irradiated with UV radiation.
• a metal-alkoxide solution in particular an indium-isopropoxide solution
• JP 09-157855 A (Kansai Shin Gijutsu Kenkyusho KK) describes the preparation of metal oxide films from metal-alkoxide solutions via a metal-oxide-sol-intermediate, which is applied to the substrate and converted by UV radiation into the respective metal oxide become.
• the resulting metal oxide may be indium oxide.
• CN 1280960 A describes the preparation of an indium-tin oxide layer from solution via a sol-gel process in which a mixture of metal alkoxides dissolved in a solvent, hydrolyzed and then used to coat a substrate with subsequent drying and curing becomes.
• the sol-gel methods have in common that their gels either because of the high viscosity are not suitable for use in printing processes and / or, especially in the case of low concentration solutions, the resulting indium oxide-containing layers inhomogeneities and thus poor film parameters exhibit.
• This roughness has a disadvantageous effect on the layer properties of the indium oxide-containing layer (above all, too low charge carrier mobilities for semiconductor applications) and on the other disadvantageous for the application of further layers for the production of a component.
• JP 11-106935 A (Fuji Photo Film Co. Ltd.) describes a method for producing a conductive metal-oxide film on a transparent substrate in which curing temperatures are achieved below 250 ° C., preferably below 100 ° C., a coating composition comprising a metal alkoxide and / or a metal salt is thermally dried on a transparent substrate and subsequently converted with UV or VIS radiation.
• JP 2007-042689 A describes metal alkoxide solutions which necessarily contain zinc alkoxides and may furthermore contain indium alkoxides, as well as processes for the production of semiconductor components which use these metal alkoxide solutions.
• the metal alkoxide films are thermally treated and converted to the oxide layer.
• pure indium oxide films can not be produced by the metal alkoxide solutions and processes described in JP 2007-042689A.
• pure indium oxide layers tend to the already mentioned (partial) crystallization, which leads to a reduced charge carrier mobility.
• a process for the preparation of semiconducting indium oxide layers in which a substrate with a liquid, anhydrous composition a) at least one indium alkoxide and b) coating comprising at least one solvent, optionally dried and at temperatures greater than 250 0 C. is thermally treated.
• an indium oxide layer is to be understood as meaning a metal-containing layer which can be produced from the abovementioned indium alkoxides and which has essentially indium atoms or ions, the indium atoms or ions being substantially oxidic.
• the indium oxide layer may also still have carbene or alkoxide shares from an incomplete conversion.
• These semiconducting indium oxide layers which can be produced according to the invention have charge carrier mobilities between 1 and 50 cm 2 A / s (measured at 50 V gate-source voltage, 50 V drain-source voltage, 1 cm channel width and 20 ⁇ m channel length)
• the model of the "Gradual Channel Approximation" can be determined using the formulas known from classical MOSFETs.
• I D is the drain current
• U D s is the drain-source voltage
• U G s is the gate-source voltage
• W the width of the transistor channel
• L the channel length of the transistor
• ⁇ the Carrier mobility and U T are the threshold voltage.
• liquid water-free compositions according to the present invention are those containing less than 200 ppm H 2 O. Appropriate drying steps necessary for the adjustment correspondingly lower water contents of the solvents, are known to the person skilled in the art.
• the indium alkoxide is preferably an indium (III) alkoxide. More preferably, the indium (III) alkoxide is an alkoxide having at least one C 1 to C 15 alkoxy or oxyalkylalkoxy group, more preferably at least one C 1 to C 10 alkoxy or oxyalkylalkoxy group. Most preferably, the indium (III) alkoxide is an alkoxide of the general formula In (OR) 3 in which R is a C 1 to C 15 alkyl or alkyloxyalkyl group, even more preferably a C 1 to C 10 alkyl or Alkyloxyalkyl group represents.
• this indium (III) alkoxide is In (OCHs) 3 , In (OCH 2 CHs) 3 , In (OCH 2 CH 2 OCHs) 3 , In (OCH (CH 3 ) 2 ) 3 or ln (O (CH 3 ) 3 ) 3 . Still more preferably, ln (OCH (CH 3 ) 2 ) 3 (indium isopropoxide) is used.
• the indium alkoxide is preferably present in proportions of from 1 to 15% by weight, more preferably from 2 to 10% by weight, most preferably from 2.5 to 7.5% by weight, based on the total weight of the composition.
• the formulation also contains at least one solvent, ie the formulation may contain both a solvent or a mixture of different solvents.
• aprotic and weakly protic solvents ie those selected from the group of aprotic nonpolar solvents, ie alkanes, substituted alkanes, alkenes, alkynes, aromatics with or without aliphatic or aromatic substituents, halogenated hydrocarbons, tetramethylsilane Group of aprotic polar solvents, ie the ethers, aromatic ethers, substituted ethers, esters or acid anhydrides, ketones, tertiary amines, nitromethane, DMF (dimethylformamide), DMSO (dimethylsulfoxide) or propylene carbonate and the weak protic solvent, ie the alcohols, the primary and secondary amines and formamide.
• aprotic and weakly protic solvents ie those selected from the group of aprotic nonpolar solvents,
• Particularly preferably usable solvents are alcohols and also toluene, xylene, anisole, mesitylene, n-hexane, n-heptane, tris (3,6-dioxaheptyl) -amine (TDA), 2-aminomethyltetrahydrofuran, phenetole, 4-methylanisole, 3 Methylanisole, methyl benzoate, N-methyl-2-pyrrolidone (NMP), tetralin, ethyl benzoate and diethyl ether.
• Very particularly preferred solvents are isopropanol, tetrahydrofurfuryl alcohol, tert-butanol and toluene and their mixtures.
• the composition used in the process according to the invention preferably has a viscosity of from 1 nnPa.s to 10 Pa.s, in particular from 1 to 10 rnPa.s determined in accordance with DIN 53019 parts 1 to 2 and measured at room temperature to achieve particularly good printability , Corresponding viscosities may be obtained by adding polymers, cellulose derivatives, or e.g. can be adjusted under the trade name Aerosil available SiO2, and in particular by PMMA, polyvinyl alcohol, urethane or Polyacrylatverdicker.
• the substrate used in the method according to the invention is preferably a substrate consisting of glass, silicon, silicon dioxide, a metal or transition metal oxide, a metal or a polymeric material, in particular PE or PET.
• the process according to the invention is particularly advantageously a coating process selected from printing processes (in particular flexographic / gravure printing, inkjet printing, offset printing, digital offset printing and screen printing), spraying processes, spin-coating processes and dip processes (dip -coating ").
• printing processes in particular flexographic / gravure printing, inkjet printing, offset printing, digital offset printing and screen printing
• spraying processes spin-coating processes and dip processes (dip -coating ").
• the printing process of the invention is a printing process.
• the coated substrate After coating and before conversion, the coated substrate can continue to be dried. Corresponding measures and conditions for this are known to the person skilled in the art.
• the conversion to indium oxide is carried out according to the invention by temperatures of greater than 250 0 C. However, particularly good results can be achieved if temperatures of 250 0 C to 360 0 C are used for the conversion. It typically uses conversion times from a few seconds to several hours.
• the conversion can also be assisted by irradiating UV, IR or VIS radiation during the thermal treatment or by treating the coated substrate with air or oxygen. It is also possible to bring the layer obtained after the coating step in contact with water and / or hydrogen peroxide before the thermal treatment and to first convert this to a metal hydroxide in an intermediate step before the thermal conversion takes place.
• the quality of the layer produced by the process according to the invention can furthermore be determined by a combined temperature and gas treatment (with H 2 or O 2 ) following the conversion step, plasma treatment (Ar, N 2 , O 2 or H 2 plasma), laser Treatment (with wavelengths in the UV, VIS or IR range) or an ozone treatment can be further improved.
• a combined temperature and gas treatment with H 2 or O 2
• plasma treatment Ar, N 2 , O 2 or H 2 plasma
• laser Treatment with wavelengths in the UV, VIS or IR range
• an ozone treatment can be further improved.
• the invention furthermore relates to indium oxide layers which can be prepared by the process according to the invention.
• the indium oxide layers which can be produced by the process according to the invention are furthermore advantageously suitable for the production of electronic components, in particular the production of (thin film) transistors, diodes or solar cells.
• Example 1 Influence of water
• a doped silicon substrate having an edge length of about 15 mm and having an approximately 200 nm thick silicon oxide coating and ITO / gold finger structures was coated with 100 ⁇ l of a 5% by weight solution of indium (III) isopropoxide in isopropanol by spin-coating. Coating (2000 rpm) coated. To exclude water, dry solvents (less than 200 ppm water) were used and the coating was still carried out in a glove box (less than 10 ppm H 2 O).
• the coated substrate was annealed in air at a temperature of 350 ° C. for one hour.
• a doped silicon substrate having an edge length of about 15 mm and an approximately 200 nm thick silicon oxide coating and finger structures of ITO / gold was prepared under the same conditions as above with 100 ⁇ l of a 5% by weight solution of indium (III). -Isopropoxid in isopropanol by spin coating (2000 rpm) coated, with the difference that no dried solvents were used (water content> 1000 ppm) and the coating was carried out not in the glove box, but in air.
• the coated substrate was annealed in air at a temperature of 350 ° C. for one hour.
• Figure 1 shows an SEM image of the resulting In 2 ⁇ 3 layer of the coating according to the invention
• Figure 2 shows a corresponding SEM image of the comparative example.
• the coating according to the invention shows a charge carrier mobility of 2.2 cm 2 A / s (at 50 V gate-source voltage, 50 V source-drain voltage, 1 cm channel width and 20 ⁇ m channel length).
• the charge carrier mobility in the layer of the comparative example is only 0.02 cm 2 A / s (at 50 V gate-source voltage, 50 V source-drain voltage, 1 cm channel width and 20 ⁇ m channel length).
• the coated substrate was annealed in air at various temperatures for one hour. This results in different charge carrier mobilities (measured at 50 V drain-gate voltage, 50 V source-drain voltage, 1 cm channel width and 20 ⁇ m channel length), which are listed in Table 1 below:

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• 2009
  • 2009-02-17 DE DE102009009337A patent/DE102009009337A1/de not_active Ceased
• 2010
  • 2010-02-05 WO PCT/EP2010/051432 patent/WO2010094583A1/de not_active Ceased
  • 2010-02-05 US US13/201,107 patent/US9194046B2/en not_active Expired - Fee Related
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