EP3284110A1 - Milieux dopants, formant barrière à une diffusion parasitaire et imprimables, à base de sol-gel et destinés au dopage local de tranches de silicium - Google Patents

Milieux dopants, formant barrière à une diffusion parasitaire et imprimables, à base de sol-gel et destinés au dopage local de tranches de silicium

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Publication number
EP3284110A1
EP3284110A1 EP16711776.1A EP16711776A EP3284110A1 EP 3284110 A1 EP3284110 A1 EP 3284110A1 EP 16711776 A EP16711776 A EP 16711776A EP 3284110 A1 EP3284110 A1 EP 3284110A1
Authority
EP
European Patent Office
Prior art keywords
aluminum
doping
printable
silicon
hybrid
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Withdrawn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
EP16711776.1A
Other languages
German (de)
English (en)
Inventor
Oliver Doll
Ingo Koehler
Sebastian Barth
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.)
Merck Patent GmbH
Original Assignee
Merck Patent GmbH
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 Merck Patent GmbH filed Critical Merck Patent GmbH
Publication of EP3284110A1 publication Critical patent/EP3284110A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0216—Coatings
    • H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/02167—Coatings for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • 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
    • C23C18/06—Coating on selected surface areas, e.g. 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
    • 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
    • C23C18/1254—Sol or sol-gel processing
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/02—Elements
    • C30B29/06—Silicon
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B31/00—Diffusion or doping processes for single crystals or homogeneous polycrystalline material with defined structure; Apparatus therefor
    • C30B31/04—Diffusion or doping processes for single crystals or homogeneous polycrystalline material with defined structure; Apparatus therefor by contacting with diffusion materials in the liquid state
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B31/00—Diffusion or doping processes for single crystals or homogeneous polycrystalline material with defined structure; Apparatus therefor
    • C30B31/06—Diffusion or doping processes for single crystals or homogeneous polycrystalline material with defined structure; Apparatus therefor by contacting with diffusion material in the gaseous state
    • C30B31/08—Diffusion or doping processes for single crystals or homogeneous polycrystalline material with defined structure; Apparatus therefor by contacting with diffusion material in the gaseous state the diffusion materials being a compound of the elements to be diffused
    • 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
    • H01L21/22—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities
    • H01L21/2225—Diffusion sources
    • 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
    • H01L21/22—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities
    • H01L21/223—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities using diffusion into or out of a solid from or into a gaseous phase
    • 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
    • H01L21/22—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities
    • H01L21/225—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities using diffusion into or out of a solid from or into a solid phase, e.g. a doped oxide layer
    • H01L21/2251—Diffusion into or out of group IV semiconductors
    • H01L21/2254—Diffusion into or out of group IV semiconductors from or through or into an applied layer, e.g. photoresist, nitrides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/547—Monocrystalline silicon PV cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a novel printable paste in the form of a hybrid gel based on precursors of inorganic oxides, which can be used in a simplified process for the production of solar cells, wherein the hybrid gel according to the invention both as
  • Doping medium and acts as a diffusion barrier.
  • a silicon wafer (monocrystalline, multicrystalline or quasi-monocrystalline, p- or n-type base doping) is freed of adherent saw damage by means of an etching process and "simultaneously", usually in the same etching bath, texturized under texturing is in this case the creation of a preferred Surface (texture) as a result of the etching step or simply to understand the targeted, but not particularly oriented roughening of the wafer surface
  • the aforementioned etching solutions for treating the silicon wafers typically consist of dilute potassium hydroxide solution to which isopropyl alcohol has been added as solvent. Instead, other alcohols having a higher vapor pressure or higher boiling point than isopropyl alcohol may be added, provided that desired etching result can be achieved.
  • the desired etch result is a morphology that is randomly-etched, or rather etched out of the original surface.
  • Pyramids is characterized by square base.
  • the density, the height and thus the base area of the pyramids can be influenced by a suitable choice of the above-mentioned constituents of the etching solution, the etching temperature and the residence time of the wafers in the etching basin.
  • Temperature range of 70 - ⁇ 90 ° C performed, with ⁇ tzabträge of up to 10 pm per wafer side can be achieved.
  • the etching solution may consist of potassium hydroxide solution with an average concentration (10-15%).
  • this etching technique is hardly used in industrial practice. More often becomes one
  • Etching solution consisting of nitric acid, hydrofluoric acid and water used.
  • This etching solution can be modified by various additives such as sulfuric acid, phosphoric acid, acetic acid, N-methylpyrrolidone and also surfactants, which u. a.
  • Wetting properties of the etching solution and their etch rate can be specifically influenced.
  • These acid etch mixtures produce a morphology of interstitially arranged etch pits on the surface.
  • the etching is typically carried out at temperatures in the range between 4 ° C to ⁇ 10 ° C and the ⁇ tzabtrag here is usually 4 pm to 6 pm.
  • the silicon wafers are included
  • the wafers are exposed in a tube furnace in a controlled atmosphere quartz glass tube consisting of dried nitrogen, dried oxygen and phosphoryl chloride.
  • the wafers are introduced at temperatures between 600 and 700 ° C in the quartz glass tube.
  • the gas mixture is transported through the quartz glass tube.
  • the phosphoryl chloride decomposes to a vapor consisting of phosphorus oxide (eg P 2 O 5) and chlorine gas.
  • the vapor of phosphorus oxide u. a. on the wafer surfaces down (occupancy).
  • the silicon surface is oxidized at these temperatures to form a thin oxide layer.
  • the deposited phosphorus oxide is embedded, whereby a mixed oxide of silicon dioxide and phosphorus oxide formed on the wafer surface.
  • This mixed oxide is called phosphosilicate glass (PSG).
  • PSG phosphosilicate glass
  • the mixed oxide serves the silicon wafer as a diffusion source, wherein in the course of the diffusion, the phosphorus oxide diffuses in the direction of the interface between PSG glass and silicon wafer and is reduced there by reaction with the silicon on the wafer surface (silicothermally) to phosphorus.
  • the resulting phosphor has a solubility which is orders of magnitude greater in silicon than in the glass matrix from which it is formed, and thus dissolves preferentially in silicon due to the very high segregation coefficient. After its dissolution, the phosphorus diffuses in the
  • the typical diffusion depth is 250 to 500 nm and is of the selected diffusion temperature (for example 880 ° C) and the total exposure time (heating & loading phase & driving phase & cooling) of the wafers in the highly heated atmosphere.
  • a PSG layer is formed, which typically has a layer thickness of 40 to 60 nm. in the
  • the drive-in phase follows. This can be decoupled from the assignment phase, but is conveniently conveniently in time directly to the
  • the composition of the gas mixture is adjusted so that the further supply of phosphoryl chloride is suppressed.
  • the surface of the silicon is further oxidized by the oxygen contained in the gas mixture, whereby a phosphorus depleted silicon dioxide layer is also generated between the actual doping source, the phosphorus oxide highly enriched PSG glass and the silicon wafer
  • the tube furnace is automatically cooled and the wafers can be removed from the process tube at temperatures between 600 ° C to 700 ° C.
  • Composition of the gas atmosphere used for doping can the formation of a so-called boron skin on the wafers are detected.
  • This boron skin is dependent on various influencing factors: decisive for the doping atmosphere, the temperature, the doping time, the
  • Pretreatment were subjected (for example, their structuring with diffusion-inhibiting and / or -unterbindenden layers and
  • Ion implantation, doping mediates via the gas phase deposition of mixed oxides, such as those of PSG and BSG (borosilicate) glass, by means of APCVD, PECVD, MOCVD and LPCVD methods,
  • the latter are often used in the so-called in-line doping, in which the corresponding pastes and inks on the side to be doped of the Wafers are applied by suitable methods. After or even during application, the solvents contained in the compositions used for doping are removed by temperature and / or vacuum treatment. As a result, the actual dopant remains on the wafer surface.
  • in-line doping in which the corresponding pastes and inks on the side to be doped of the Wafers are applied by suitable methods.
  • the solvents contained in the compositions used for doping are removed by temperature and / or vacuum treatment. As a result, the actual dopant remains on the wafer surface.
  • Doping sources for example, dilute solutions of phosphoric or boric acid, as well as sol-gel-based systems or solutions of polymeric Borazilitatien can be used.
  • Solvents from the aforementioned doping media are usually followed by a high-temperature treatment during which undesirable and interfering additives which cause the formulation are either "burned" and / or pyrolyzed., The removal of solvents and the burn-out may or may not , take place simultaneously.
  • the coated substrates usually pass through a continuous furnace at temperatures between 800 ° C and 1000 ° C, to shorten the cycle time, the temperatures in comparison to
  • Gas phase diffusion in the tube furnace can be slightly increased.
  • the prevailing in the continuous furnace gas atmosphere can according to the
  • Driving the dopant can in principle be decoupled from each other.
  • the wafers present after the doping are coated on both sides with more or less glass on both sides of the surface. More or less, in this case, refers to modifications made in the context of Doping process can be applied: double-sided diffusion vs. quasi one-sided diffusion mediated by back-to-back arrangement of two wafers in a parking space of the process boats used. The latter
  • Variant allows a predominantly one-sided doping, but does not completely prevent the diffusion on the back.
  • the wafers are on the one hand transhipped in batches in wet process boats and with their help in a solution of dilute hydrofluoric acid, typically 2% to 5%, immersed and left in this until either the surface is completely removed from the glasses, or Process cycle has expired, which represents a sum parameter of the necessary ⁇ tzdauer and the automatic process automation.
  • the complete removal of the glasses can be determined, for example, by the complete dewetting of the silicon wafer surface by the dilute aqueous hydrofluoric acid solution.
  • the complete removal of a PSG glass is achieved under these process conditions, for example with 2% hydrofluoric acid solution within 210 seconds at room temperature.
  • the etching of corresponding BSG glasses is slower and requires longer process times and possibly also higher
  • the etching of the glasses on the wafer surfaces can also be carried out in a horizontally operating method in which the wafers are introduced in a constant flow into an etching system in which the wafers pass through the corresponding process tanks horizontally (inline system).
  • the wafers are conveyed on rollers and rollers either through the process tanks and the etching solutions contained therein or the etching media are transposed onto the wafer surfaces by means of roller application.
  • the typical residence time of the wafers in the case of etching the PSG glass is about 90 seconds, and the hydrofluoric acid used is somewhat more concentrated than in the batch process
  • the concentration of hydrofluoric acid is typically 5%.
  • the tank temperature compared to the
  • edge insulation -> glass etching is a process engineering necessity, which results from the system-inherent characteristics of the double-sided diffusion, even with intentional unilateral back-to-back diffusion.
  • edge insulation is a process engineering necessity, which results from the system-inherent characteristics of the double-sided diffusion, even with intentional unilateral back-to-back diffusion.
  • parasitic p-n transition On the (later) back side of the solar cell, there is a large-scale parasitic p-n transition, which, although due to process technology, is partly, but not completely, removed in the course of the later processing. As a result, the front and back of the solar cell are parasitic and parasitic
  • the wafers are unilaterally via an etching solution
  • etching solution consisting of nitric acid and hydrofluoric acid.
  • the etching solution may contain as minor constituents, for example, sulfuric acid or phosphoric acid.
  • the etching solution is imparted via rollers to the
  • etch removal typically achieved with these methods is about 1 pm of silicon at temperatures between 4 ° C. and 8 ° C. (including that on the surface to be treated
  • edge isolation can also be done with the help of
  • Plasma etching processes are performed. This plasma etching is then usually carried out before the glass etching. For this purpose, several wafers are stacked on each other and the outer edges become the plasma
  • the plasma is filled with fluorinated gases, for example
  • Tetrafluoromethane fed.
  • Solar cells with an anti-reflection coating which usually consists of amorphous and hydrogen-rich silicon nitride.
  • Antireflection coatings are conceivable. Possible coatings may include titanium dioxide, magnesium fluoride, tin dioxide and / or
  • the layer generates an electric field due to the numerous incorporated positive charges, that charge carriers in the silicon can keep away from the surface and the recombination speed of these charge carriers at the
  • this layer depending on its optical parameters, such as refractive index and layer thickness, this layer generates a reflection-reducing property which contributes to the fact that more light can be coupled into the later solar cell. Both effects can increase the conversion efficiency of the solar cell.
  • the antireflection reduction is most pronounced in the wavelength range of the light of 600 nm.
  • the directional and non-directional reflection shows a value of about 1% to 3% of the originally incident light (perpendicular incidence to the surface normal of the silicon wafer).
  • the above-mentioned silicon nitride films are currently generally deposited on the surface by a direct PECVD method.
  • a gas atmosphere of argon a plasma is ignited, in which silane and Ammonia are introduced.
  • the silane and the ammonia are converted in the plasma by ionic and radical reactions to silicon nitride and thereby deposited on the wafer surface.
  • the properties of the layers can z. B. adjusted and controlled by the individual gas flows of the reactants.
  • the deposition of the above-mentioned silicon nitride layers can also be carried out using hydrogen as the carrier gas and / or the reactants alone. Typical deposition temperatures are in the range between 300 ° C to 400 ° C.
  • Alternative deposition methods may be, for example, LPCVD and / or sputtering.
  • Silicon nitride coated wafer surface defines the front electrode.
  • the electrode has been established using the screen printing method using metallic
  • the sum of the residual constituents results from the necessary for the formulation of the paste theological aids, such as solvents, binders and thickeners.
  • the silver paste contains a special Glasfrit mixture, mostly oxides and mixed oxides based on
  • the glass frit fulfills essentially two functions: on the one hand it serves as a bonding agent between the wafer surface and the mass of the silver particles to be sintered, on the other hand it is responsible for the penetration of the silicon nitride covering layer in order to enable the direct ohmic contact to the underlying silicon.
  • the penetration of the silicon nitride takes place via an etching process with subsequent diffusion of silver present dissolved in the glass frit matrix into the silicon surface, whereby the ohmic contact formation is achieved.
  • the silver paste is deposited by screen printing on the wafer surface and then at temperatures of about 200 ° C to 300 ° C for a few Dried for a few minutes.
  • double-printing processes also find industrial application, which make it possible to print on an electrode grid generated during the first printing step, a congruent second.
  • Silver metallization increases, which can positively influence the conductivity in the electrode grid.
  • the solvents contained in the paste are expelled from the paste.
  • the printed wafer passes through a continuous furnace.
  • Such an oven generally has several heating zones, which can be independently controlled and tempered.
  • the wafers are heated to temperatures up to about 950 ° C. However, the single wafer is typically exposed to this peak temperature for only a few seconds. During the remaining run-up phase, the wafer has temperatures of 600 ° C to 800 ° C. In these
  • Temperatures are contained in the silver paste contained organic impurities, such as binders, and the etching of the silver paste.
  • Silicon nitride layer is initiated. During the short time interval of the prevailing peak temperatures, contact formation occurs.
  • the process of contact formation outlined so briefly is usually carried out simultaneously with the two remaining contact formations (see Figures 6 and 7), which is why in this case one also speaks of a co-firing process.
  • the front electrode grid consists of thin fingers
  • the typical height of the printed silver elements is typically between 10 pm and 25 ym.
  • the aspect ratio is rarely greater than 0.3.
  • the rear bus buses are also usually by means of
  • the back electrode is defined following the pressure of the bus buses.
  • the electrode material is made of aluminum, therefore, to define the electrode, an aluminum-containing paste by screen printing on the remaining free area of the wafer back with a
  • Edge distance ⁇ 1 mm is printed.
  • Aluminum assembled The remaining components are those already mentioned under point 5 (such as solvents, binders, etc.).
  • the aluminum paste is bonded to the wafer during co-firing by causing the aluminum particles to start to melt during heating and remove silicon from the wafer in the wafer
  • the melt mixture acts as a dopant source and gives aluminum to the silicon (solubility limit: 0.016 atomic percent), whereby the silicon is p + doped as a result of this drive-in.
  • the wafer will precipitate on the wafer surface u. a. a eutectic mixture of aluminum and silicon, which solidifies at 577 ° C and has a composition with a mole fraction of 0.12 Si.
  • This potential wall is generally referred to as the back surface field or back surface field.
  • edge isolation of the wafer has not already been carried out as described under point 3, this is typically carried out after co-firing with the aid of laser beam methods.
  • a laser beam is directed to the front of the solar cell and the front p-n junction is severed by means of the energy coupled in by this beam.
  • This trench with a depth of up to 15 ⁇ due to
  • this laser trench is 30 ⁇ to 60 ⁇ wide and about 200 ⁇ away from the edge of the solar cell.
  • solar cell architectures with both n-type and p-type base material. These solar cell types include u. a. ⁇ PERC solar cells
  • structured diffusion barriers may be deposited on the silicon wafers prior to depositing the glasses to define the regions to be doped.
  • a disadvantage of this method is that in each case only one polarity (n or p) of
  • Wafer surfaces deposited dopant sources This method makes it possible to save costly structuring steps. However, it can not compensate for the disadvantage of a possible simultaneous simultaneous doping of two polarities on the same surface at the same time (co-diffusion), since this method is also based on a predeposition of a dopant source, which is activated only subsequently for the emission of the dopant. Disadvantage of this (post-) doping from such sources is the inevitable laser damage to the substrate: the laser beam must by absorbing the radiation into heat
  • Phosphorylchlond and / or boron tribromide do not allow to selectively generate local dopants and / or locally different dopants on silicon wafers.
  • the creation of such structures is possible by using known doping technologies only by consuming and costly structuring of the substrates. When structuring different dopants and / or locally different dopants on silicon wafers.
  • the doping source must have a sufficiently pasty
  • Gelation of the hybrid gels of the invention can be adjusted.
  • the intrinsic viscosity of the hybrid gels can be further adjusted as desired by the addition of waxes and waxy additives and additives as desired.
  • the waxes and waxy additives used for the formulation are dissolved and / or melted in gelled paste mixture.
  • waxes and waxy additives used in the formulation act associatively and co-thickening in synthesized and gelled pastes, without the additives being thickeners in the classical sense. Furthermore, the associative, intrinsic viscosity-affecting waxes and waxy compounds have an advantageous effect on the adjustment of the glass layer thickness resulting from the printed hybrid gels as well as on their individual drying resistance to stress.
  • the subject of the present invention is therefore printable
  • Silica, alumina and boron oxide which preferably by means of of the screen printing method on silicon surfaces for the purpose of local and / or full-area, one-sided diffusion and doping in the production of solar cells, preferably of highly efficient structured doped solar cells, printed, nachlagernd dried and then by means of a suitable high-temperature process for
  • Silicon atom may have attached hydrogen atom, such as triethoxysilane, and further wherein a
  • Degree of substitution refers to the number of possible existing carboxy and / or alkoxy groups, which have both single and different saturated, unsaturated branched, unbranched aliphatic, alicyclic and aromatic radicals in each case at alkyl and / or alkoxy and / or carboxy groups, which in turn at any position of the alkyl, alkoxide or carboxy radical may be functionalized by heteroatoms selected from the group O, N, S, Cl and Br, as well as mixtures of the abovementioned
  • Aluminum alcoholates such as aluminum triethanolate
  • reaction conditions can be influenced by the fact that highly viscous mixtures are in the form of pasty formulations or also pastes which mix with printing processes suitable for such mixtures, preferably the
  • the printable paste hybrid gel according to the invention is a composition which can be adjusted by the addition of waxes and waxy compounds in an amount of up to 25% based on the final total mixture of the paste in terms of its pasty and pseudoplastic properties, the waxes and waxy compounds selected from the group consisting of beeswax, synchro wax, lanolin, carnauba wax, jojoba, Japan wax and the like, fatty acids and fatty alcohols, fatty glycols, esters
  • Substance classes should each contain branched and unbranched carbon chains with chain lengths greater than or equal to twelve carbon atoms, single-phase and / or biphasic, emulsifying or suspending, thickening and thus make the classical use of polymeric thickeners superfluous.
  • Hybrid gel is particularly well suited for use as a doping medium in the processing of silicon wafers for photovoltaic, microelectronic, micromechanical and micro-optical applications.
  • novel paste-like ones described herein are
  • Hybrid gels are suitable for the production of PERC, PERL, PERT, IBC solar cells and other high-performance solar cells, which feature further architectural features such as MWT, EWT, Selective Emitter, Selective Front Surface Field, Selective Back Surface Field and Bifaciality.
  • MWT MWT
  • EWT Selective Emitter
  • Selective Front Surface Field Selective Back Surface Field and Bifaciality.
  • Layers on silicon wafers can be used.
  • the hybrid gel is applied using one or more to be carried out sequentially Temper Colouren (tempering by means of a step function) and / or an annealing ramp, dried and compacted to the glazing, which forms grip and abrasion resistant layers with a thickness of up to 500 nm.
  • Using the printable hybrid gel according to the invention can influence the conductivity of the substrate by drying corresponding to surfaces applied to layers, compacted and vitrified and from the vitrified layers by heat treatment at a
  • Silicon wafer surfaces with dopants of opposite polarity is induced by conventional gas phase diffusion and wherein the printed hybrid gel acts as a diffusion barrier to the dopants of opposite polarity.
  • Solar cells using the paste-shaped hybrid gel according to the invention are characterized in that a) hybrid gels are printed on silicon wafers, dried and compacted onto the printed gels, and then subjected to subsequent gas phase diffusion with, for example, phosphoryl chloride to yield p-type dopants in the printed areas of the wafers and n-type dopants in the areas exclusively exposed to gas-phase diffusion,
  • the silicon wafer is printed locally with the hybrid gel, wherein the structured landfill may optionally have alternating lines, the printed structures dried and compacted and subsequently over the entire surface with the aid of PVD and / or CVD-deposited doped glasses doping in silicon of opposite polarity, can be coated and encapsulated, and the
  • the overlapping overall structure is brought to the structured doping of the silicon wafer by suitable high-temperature treatment, wherein the printed hybrid gel acts as a diffusion barrier with respect to the glass above it and the dopant contained therein.
  • a paste is to be understood as meaning a composition which, due to the sol-gel-based synthesis, has a high viscosity of more than 500 mPa * s and is no longer flowable.
  • the printable, highly viscous oxide media also referred to below as hybrid gels
  • Silicon dioxide one to fourfold symmetric and asymmetric
  • Silicon atom may have attached hydrogen atom, such as
  • triethoxysilane and further wherein a degree of substitution refers to the number of possible existing carboxy and / or alkoxy groups, which in both alkyl and / or alkoxy and / or
  • Carboxy groups have individual or different saturated, unsaturated branched, unbranched aliphatic, alicyclic and aromatic radicals, which in turn may be functionalized at any position of the alkyl, alkoxide or the carboxy radical by heteroatoms selected from the group O, N, S, Cl and Br, and mixtures of the aforementioned precursors.
  • Individual compounds which are mentioned in the above are mentioned in the above.
  • Claims are: tetraethyl orthosilicate and the like,
  • Triethoxysilane ethoxytrimethylsilane, dimethyldimethoxysilane,
  • Aluminum alcoholates such as aluminum triethanolate
  • Aluminum tristearate aluminum carboxylates such as basic aluminum acetate, aluminum triacetate, basic aluminum formate, aluminum tri-formate and aluminum trioctoate, aluminum hydroxide, aluminum metahydroxide and
  • Boron oxide diboroxide, simple boric acid alkyl esters, such as triethyl borate,
  • glycerol for example, glycerol, functionalized 1, 3-glycols, such as, for example,
  • boric acid esters with boric acid esters containing the aforementioned structural motifs as structural subunits, such as
  • boric acid esters from ethanolamine, diethanolamine, triethanolamine, propanolamine, dipropanolamine and tripropanolamine, mixed anhydrides of boric acid and
  • Carboxylic acids such as tetraacetoxy diborate, boric acid,
  • the hybrid gels may contain further substances which can confer advantageous properties on the gels. They may be: oxides, basic oxides, hydroxides, alkoxides, carboxylates, ⁇ -diketonates, ⁇ -ketoesters, silicates and the like of cerium, tin, zinc, titanium, zirconium, hafnium, zinc, germanium, gallium, niobium, yttrium, which in the sol-gel synthesis can be used directly or pre-condensed application.
  • oxides oxides, basic oxides, hydroxides, alkoxides, carboxylates, ⁇ -diketonates, ⁇ -ketoesters, silicates and the like of cerium, tin, zinc, titanium, zirconium, hafnium, zinc, germanium, gallium, niobium, yttrium, which in the sol-gel synthesis can be used directly or pre-condensed application.
  • Hybrid gels can be prepared using anhydrous as well as hydrous sol-gel synthesis.
  • the following substances can be used advantageously:
  • Oxid precursors, as suitable carbonyls can at least serve: Formic acid, acetic acid, oxalic acid, trifluoroacetic acid, mono-, di- and trichloroacetic acid, glyoxylic acid, tartaric acid, maleic acid, malonic acid, pyruvic acid, malic acid, 2-oxoglutaric acid
  • particulate additives eg aluminum hydroxides and
  • Titanium dioxide, titanium carbide, titanium nitride, titanium carbonitride for influencing the dry film thicknesses resulting after drying and their morphology
  • particulate additives eg aluminum hydroxides and
  • Titanium dioxide, titanium carbide, titanium nitride, titanium carbonitride for influencing the scratch resistance of the dried films
  • Capping agent selected from the group acetoxytrialkylsilanes,
  • Waxes and waxy compounds such as beeswax
  • Substance classes should each contain branched and unbranched carbon chains with chain lengths greater than or equal to twelve carbon atoms.
  • the hybrid gels can be prepared by adding appropriate
  • Masking agents, complex and chelating in a sub stoichiometric to a stoichiometric ratio on the one hand sterically stabilize and on the other hand in terms of their condensation and gelling rate but also in terms of the rheological properties targeted influence and control. Suitable masking and complexing agents, as well
  • Chelating agents for example, acetylacetone,, 3-cyclohexanedione, isomeric compounds of dihydroxybenzoic acids, acetaldoxime, as well as those disclosed and contained in the patent applications WO 2012/1 9686 A, WO20121 19685 A1, WO20121 19684 A, EP12703458.5 and EP12704232.3. The content of these publications is therefore included in the disclosure of the present application.
  • the hybrid gels can be applied to the surface of silicon wafers using printing and coating techniques.
  • These can be: spin coating or dip coating, drop casting, curtain or slot dye coating, screen printing or flexoprinting, gravure, ink jet or aerosol jet printing, offset printing, microcontact printing,
  • Electrohydrodynamic dispensing, roller or spray coating, ultrasonic spray coating, pipe jetting, laser transfer printing, pedd printing or rotary screen printing Preferably, printing of the hybrid gels is accomplished by the screen printing method.
  • Silicon wafers printed hybrid gels are subjected to a drying step following their landfill. This drying may, but not necessarily, be done in a continuous furnace. During the drying of the gels, they are compacted as a result of the spewing out of solvents, as well as the thermal degradation of formulation auxiliaries and of the oxide precursors into homogeneous and tightly closing vitreous layers.
  • the thus prepared, printable and dried hybrid gels are particularly well suited for use as a doping medium in the
  • hybrid gels are particularly suitable for the production of PERC, PERL, PERT, IBC solar cells (BJBC or BCBJ) and others, wherein the solar cells further architectural features, such as MWT, EWT, selective emitter, selective front surface field, selective Have back surface field and bifaciality. Furthermore, the solar cells further architectural features, such as MWT, EWT, selective emitter, selective front surface field, selective Have back surface field and bifaciality. Furthermore, the
  • Glass layers which act as a sodium and potassium diffusion barrier in the LCD technology due to a thermal treatment, in particular for Production of thin, dense glass layers on the cover glass of a display, consisting of doped S1O2, which prevent the diffusion of ions from the cover glass into the liquid-crystalline phase.
  • the surface-printed hybrid gel prepared by a process within the scope of the invention is particularly preferred in a temperature range between 50 ° C and 750 ° C, preferably between 50 ° C and 500 ° C between 50 ° C and 400 ° C, using one or more, to be carried out sequentially Temper Colouren (tempering by a step function) and / or an annealing ramp, dried and compacted to the glazing, forming a grip and abrasion resistant layer, may have thicknesses of up to 500 nm.
  • a heat treatment of the vitrified on the surfaces layers at a temperature in the range between 750 ° C and 1100 ° C, preferably between 850 ° C and 1 00 ° C, more preferably between 850 ° C and 1000 ° C.
  • silicon such as boron in the present case
  • Treatment duration and the treatment temperature can be transported in depths of up to 1 ⁇ , and electrical layer resistances of less than 10 ⁇ / sqr are adjustable.
  • the surface concentration of the dopant can reach values greater than or equal 1 * 10 19 1 * 0 20 to several
  • Atoms / cm 3 and depends on the type of dopant used in the printable hybrid gel. It has proved to be particularly advantageous hereby that subsequently the
  • this result can be achieved by printing the hybrid gel as a doping medium on hydrophilic (wet-chemical and / or native oxide) and / or hydrophobic (silane-terminated) silicon wafer surfaces.
  • composition of the hybricle proportions of the doping oxide precursor to those of the accompanying oxide precursors, mainly but not exclusively glass forming
  • this process can be used to produce grip and abrasion-resistant oxidic layers which have a doping effect on silicon and silicon wafers a) silicon wafers are printed with the hybrid gels according to the invention, the printed Dotiermedien dried, compacted and
  • III. is removed from the wafer surface by means of subsequent sequential wet chemical treatment with nitric and hydrofluoric acid or
  • Phosphoryl chloride in the case of a used n-type doping medium or with, for example, boron trichloride or boron tribromide in the case of a p-type doping medium used, whereby high dopings in the non-printed areas and lower
  • Phosphoryl chloride in the case of a used n-type doping medium or with, for example, boron trichloride or boron tribromide in the case of a p-type doping medium used can be obtained, whereby low doping in the non-printed areas and high dopants in the printed areas can be obtained, in that
  • Source concentration of the hybrid gels used was controlled by synthesis sufficiently controlled, and the glass obtained from the hybrid gel according to the invention and the
  • hybrid gel deposited over the entire surface of the silicon wafer is dried and / or compacted and from the compacted hybrid doping gel with the aid of laser irradiation, the local doping of the underlying substrate material is initiated,
  • Heat treatment initiated the doping of the underlying substrate and subsequently with subsequent local
  • the silicon wafer either over the entire surface or locally with the
  • the printed hybrid structures according to the invention, optionally by alternating structures, the printed structures are dried and compacted, the negatives of the alternating structures are printed by means of oppositely doping acting materials and as a result of suitable heat treatment for structured doping of the
  • hybrid gels according to the invention are optionally printed in an alternating structure sequence of arbitrary structure width, for example line width, adjacent to non-printed silicon surface also characterized by an arbitrary structure width, the printed structures are dried and compacted, after which the wafer of a conventional
  • Gas phase diffusion and doping is subjected by means of phosphoryl chloride or phosphorus pentoxide and thereby acts either locally or over the entire area applied hybrid gel as a diffusion barrier to the mediated via the gas phase dopant and consequently not printed with the hybrid gel according to the invention
  • Wafer surfaces of an opposite doping, in this case with phosphorus, are subjected; if necessary, the opposite surface printed with the hybrid gel must or can be suitably etched back by means of suitable wet-chemical etching steps, or
  • hybrid gels according to the invention are optionally printed in an alternating structure sequence of arbitrary structure width, for example line width, adjacent to non-printed silicon surface likewise characterized by any structure width, the printed structures are dried and compacted, after which the entire surface of the wafer is coated with a
  • Wafer surface can be provided (encapsulation), the latter doping media printable sol-gel-based oxidic dopants, other printable dopants and / or pastes, doped APCVD and / or PECVD glasses and dopants from conventional gas phase diffusion and doping can be, and the overlapping arranged and doping acting doping due to suitable heat treatment for doping of the substrate are brought and in this context, the bottom befindliches printed hybrid dot-acting hybrid gel due to suitable segregation coefficients and insufficient diffusion lengths as a diffusion barrier to behave over it, the contrasting majority majority carrier polarity inducing doping medium must behave; further comprising the other side of the wafer surface by means of an otherwise and otherwise deposited (printed, CVD, PVD) diffusion barrier, such as
  • Silicon dioxide or silicon nitride or silicon oxynitride may be covered, but need not necessarily be
  • the silicon wafer either over the entire surface or locally with the
  • hybrid gels according to the invention are optionally printed in an alternating structure sequence of arbitrary structure width, for example line width, adjacent to non-printed silicon surface likewise characterized by any structure width, the printed structures are dried and compacted, after which the entire surface of the wafer is coated with a
  • Wafer surface can be provided (encapsulation), after which then the wafer surface over the entire surface with a doping opposite inducing majority charge carrier polarity can be provided on the already printed wafer surface, the latter doping media printable sol-gel-based oxide dopants, other printable Dotiertinten and / or Pastes may be doped APCVD and / or PECVD glasses as well as dopants from conventional gas phase diffusion and doping, and the overlapping arranged doping and doping acting dopants due to appropriate heat treatment for doping of the substrate are brought and this context to support As a result of suitable segregation coefficients and inadequate
  • Hybrid gels their drying, and compression and / or doping by thermal treatment resulting glass layers with a
  • Acid mixture containing hydrofluoric acid and optionally phosphoric acid etched wherein the etching mixture used as etchant hydrofluoric acid in a concentration of 0.001 to 10 wt .-% or 0.001 to 10 wt .-%
  • the dried and compacted doping glasses can contain hydrofluoric acid and 0.001 to 10 wt .-% phosphoric acid in the mixture.
  • the dried and compacted doping glasses can the
  • Nitric acid such as the so-called p-etching, R-etching, S-etching or etch mixtures, etching mixtures consisting of flux and
  • novel high-viscosity doping pastes can be synthesized on the basis of the sol-gel process and, if necessary, can be formulated further.
  • a synthetic method is based on the dissolution of oxide precursors of the alumina in a solvent or a solvent mixture, preferably selected from the group of high-boiling glycol ethers or preferably high-boiling glycol ethers and alcohols, which
  • a suitable acid preferably a carboxylic acid, and in this case particularly preferably with formic acid or acetic acid
  • suitable complexing and chelating agents such as
  • suitable ⁇ -diketones such as acetylacetone or for example 1, 3-cyclohexanedione, ⁇ - and ⁇ -ketocarboxylic acids and their esters, such as pyruvic acid and its esters acetoacetic acid and ethyl acetoacetate, dihydroxybenzoic acids, such as 3, 5 -dihydroxybenzoic acid, and / or oximes , such as acetaldoxime, as well as other such cited compounds, as well as any mixtures of the aforementioned complex, chelating and condensation degree controlling agents, is completed.
  • the solution of the alumina precursor is then at room temperature with a mixture consisting of the o. G.
  • Solvent or solvent mixture and water added dropwise and then heated at 80 ° C for up to 24 h under reflux.
  • the gelation of the aluminum oxide precursor can be controlled in a targeted manner via the molar ratio of the aluminum oxide precursor to water, to the acid used and to the amounts of substance and the type of complexing agent used. The necessary ones
  • favoring solvents such as high-boiling glycols, Glycol ethers, Glycolethercarboxylate and further solvents such as
  • solvent mixtures adjusted to their desired properties and optionally diluted is a mixture consisting of condensed oxide precursors of
  • a suitable carboxylic anhydride such as acetic anhydride, formyl acetate or propionic anhydride or comparable
  • the paste rheology can continue to be adjusted and rounded according to and with the also previously described in detail auxiliaries and additives according to specific requirements, the use of waxes and waxy compounds according to the invention has a special role.
  • the waxes and waxy compounds according to the invention has a special role.
  • waxy compounds are dissolved or melted in the gelled paste mixture, if necessary. Refluxing and with intimate stirring. The entire formulation is then allowed to cool with intimate stirring, adjusting the desired properties of the final pseudoplastic mixture.
  • homogeneously monophasic or emulsified biphasic mixtures are obtained.
  • An alternative method of synthesis is based on the preparation of a condensed sol of oxide precursors of silicon dioxide and
  • Benzyl benzoate, butyl benzoate, THF or comparable initially charged, with a suitable carboxylic anhydride, such as acetic anhydride,
  • Formyl acetate or propionic anhydride or comparable and dissolved under reflux or reacted until a clear solution is present.
  • suitable precursors of the silicon dioxide optionally pre-dissolved in the reaction solvent used, drop by drop.
  • the reaction mixture is then heated or refluxed for up to 24 hours.
  • the sol is treated with suitable solvents such as, for example, glycols, glycol ethers, glycol ether carboxylates and also solvents such as terpineol, texanol, butyl benzoate, benzyl benzoate, dibenzyl ether, butyl benzyl phthalate, or their solvent mixtures in which suitable complexing and chelating agents, for example suitable ⁇ - Diketones, such as acetylacetone or, for example, 1, 3-cyclohexanedione, ⁇ - and ⁇ -ketocarboxylic acids and their esters, such as pyruvic acid and its esters
  • suitable solvents such as, for example, glycols, glycol ethers, glycol ether carboxylates and also solvents such as terpineol, texanol, butyl benzoate, benzyl benzoate, dibenzyl ether, butyl benzyl phthalate, or their solvent mixtures in which
  • Acetoacetic acid and ethyl acetoacetate dihydroxybenzoic acids, such as, for example, 3, 5-dihydroxybenzoic acid, and / or oximes, such as
  • acetaldoxime and other such cited compounds, as well as any mixtures of the aforementioned complex, chelating agents and the degree of condensation controlling agents are already pre-dissolved in the accompaniment of water, added and stirred, if necessary. At the same time increases the temperature of the reaction mixture.
  • the duration of mixing of the two solutions can be between 0.5 minutes and five hours.
  • the total mixture is tempered with the aid of an oil bath whose temperature is usually set to 155 ° C. After completing a suitable known duration of mixing of the two partial solutions completed
  • the reaction mixture thus completed is then heated to reflux for one to four hours.
  • the warm gelled mixture can now be prepared using other excipients already mentioned above,
  • EXAMPLE 1 A glass flask is charged with 55.2 g of ethylene glycol monobutyl ether (EGB) and 20.1 g of aluminum tri-sec-butylate (ASB) and stirred until a homogeneous mixture is obtained. To this mixture are added 7.51 g of glacial acetic acid, 0.8 g of acetaldoxime and 0.49 g of acetylacetone with stirring.
  • EGB ethylene glycol monobutyl ether
  • ASB aluminum tri-sec-butylate
  • Mass loss of volatile reaction products is 12.18 g.
  • the distilled mixture is then diluted with 62.3 g of Texanol and another 65 g of EGB, and mixed with a mixed condensed sol consisting of precursors of boron oxide and silicon dioxide.
  • the hybrid sol of silica and boron oxide is prepared as follows: 6.3 g Tetraacetoxydiborat be presented in 40 g of benzyl benzoate and treated with 15 g of acetic anhydride. The mixture is heated in an oil bath to 80 ° C and after a clear solution is formed, 4.6 g
  • the hybrid sol is then also subjected to a vacuum distillation at 70 ° C until reaching a final pressure of 30 mbar, the mass loss of volatile reaction products is 7.89 g.
  • the 110 g of the total mixture is mixed with 9 g of synchro wax and heated with stirring to 150 ° C until complete dissolution and clear mixing. Subsequently, the mixture is allowed to cool with intensive stirring. The result is a pseudoplastic and very good printable paste.
  • silicon dioxide precursors in this case a Mixture consisting of 2.3 g of dimethyldimethoxysilane and 3.4 g
  • the paste according to Example 1 using a conventional screen printing machine and a screen with 350 mesh, 16 ym thread size (stainless steel) and an emulsion thickness of 8 - 12 pm using a doctor speed of 170 mm / s and a squeegee pressure of 1 bar to one Wafer printed and then subjected to drying in a continuous furnace.
  • the heating zones in the continuous furnace are set to 350/350/375/375/375/400/400 ° C.
  • FIG. 1 shows a silicon wafer printed with the hybrid gel according to the invention after it has been dried in a continuous furnace.
  • the hybrid gel used corresponds to a composition prepared according to Example 3.
  • the paste according to Example 1 is prepared by means of a conventional
  • the wafer On boron diffusion, the wafer is exposed to phosphorous diffusion with phosphoryl chloride at low temperature, 880 ° C, in the same process tube. After the diffusion and the cooling of the wafer, it is freed from the glasses present on the wafer surfaces by means of etching with dilute hydrofluoric acid. The area, which previously with the
  • Boron paste according to the invention was printed, has a hydrophilic
  • the SIMS (secondary ion mass spectrometry) depth profile of the dopants is determined.
  • a boron doping from the wafer surface to that of the silicon is determined.
  • Paste layer thus acts as diffusion barrier against a typical phosphorus diffusion.
  • FIG. 2 shows the SIMS profile of a rough silicon surface, which is printed with the boron paste according to the invention and subsequently printed
  • EGB ethylene glycol monobutyl ether
  • ASB aluminum tri-sec-butylate
  • mixture 1 and mixture 2 are combined in a glass flask of suitable size with the addition of 261 g Texanol and 40 g
  • the gel hybrid sol is transferred to a stirred tank of suitable size and mixed with 116 g Synchrowachs ERLC. Under heating and intensive stirring of the mixture to 150 ° C is the
  • Wax melted and dissolved in the heat in the gel. After complete dissolution of the wax, the heat supply is interrupted and the mixture is allowed to cool while stirring. After cooling, a buttery, pseudoplastic, yellowish-white, very good printable paste is obtained.
  • the viscosity of the paste is 7.5 Pa * s at a shear rate of 25 / s and a temperature of 23 ° C.
  • the paste is made by means of a screen printer using a trampoline sieve with stainless steel mesh (400 mesh, 18 ⁇ m
  • a sieve jump of 2 mm a printing speed of 200 mm / s, a flood speed of 200 mm / s, a squeegee pressure of 60 N during printing and a squeegee pressure of 20 N during flooding, and using a carbon fiber squeegee with polyurethane rubber of Shore hardness of 65 °.
  • the printed wafers are then heated to 400 ° C
  • the belt speed is 90 cm / s.
  • the length of the heating zones is 3 m.
  • the paste transfer is 0.65 mg / cm 2 .
  • FIG. 3 shows the micrograph of a line screen printed and dried with a doping paste according to Example 5.
  • FIG. 4 shows a micrograph of a paste surface screen-printed and dried with a doping paste according to Example 5.
  • FIG. 5 shows a micrograph of a paste surface screen-printed and dried with a doping paste according to Example 5.
  • the printing is done with a sieve with stainless steel mesh (400/18, 10 pm
  • Emulsion thickness over the fabric The paste application is 0.9 mg / cm 2 .
  • the wafers are left on a hotplate for three minutes at 400 ° C
  • Phosphorylchloriddampf achieved, which, transported by a stream of inert gas, is introduced into the hot furnace atmosphere. Due to the high temperature prevailing in the oven and at the same time in the oven Oxygen furnace atmosphere, the phosphoryl chloride is burned to phosphorus pentoxide. The phosphorus pentoxide precipitates in conjunction with a silicon dioxide forming on the wafer surface due to the presence of oxygen in the furnace atmosphere.
  • the mixture of the silicon dioxide with the phosphorus pentoxide is also referred to as PSG glass. From the PSG glass on the
  • a PSG glass can form only on the surface of the boron paste. If the boron paste acts as a diffusion barrier to phosphorus, then at those points where the boron paste is already present, there can be none
  • Phosphorus diffusion takes place, but only one of Born itself, which diffuses from the paste layer in the silicon wafer.
  • This type of co-diffusion can be carried out in various embodiments.
  • the phosphoryl chloride can be burned in the furnace at the beginning of the diffusion process. At the beginning of the process, one generally understands one in the industrial production of solar cells
  • Possibilities can, depending on the particular requirements, also any combinations of the phases of the possible entry of phosphoryl chloride are made in the diffusion furnace. Some of these options are outlined. In Figure 6, the possibility of using a second plateau temperature is not shown.
  • the wafers printed with the boron paste are subjected to a co-diffusion process, as shown, in which the entry of the
  • Plateau temperature takes place, which to achieve a boron diffusion necessary, in this case 950 ° C.
  • the wafers in the process boat are arranged in pairs in such a way that their sides printed with boron paste are in each case facing one another. In each case, a wafer is received in a slot of the process boat.
  • the nominal distance between the substrates is thus about 2.5 mm. in the
  • the wafers are subjected to glass etching in dilute hydrofluoric acid and then their
  • Sheet resistance of 41 ⁇ / D while that of the printed with the boron paste opposite side of the wafer has a sheet resistance of 68 ⁇ / D.
  • the side which has a layer resistance of 41 ⁇ / D, is doped exclusively with p-, ie with boron, whereas the
  • FIG. 6 shows a micrograph of a line screen printed and dried with a doping paste according to Example 5.
  • FIG. 7 shows an arrangement of wafers in a process boat during a co-diffusion process.
  • Wafer surfaces are opposite.
  • Reaction mixture is heated in an oil bath to 80 ° C and for the Refluxed for 8 hours to 60 hours. During the reaction, the transparent mixture turns from colorless to yellow-orange. After completion of the reaction, the reaction mixture is at
  • Distillation loss is 60.02 g. 10 g of the residue are dissolved in 35.9 g Diethylenglycoletherdibenzoat and then diluted with 34.7 g Butoxyethoxyethylacetat and 5 g Triethylorthoformiat.
  • the solution is then heated to 90 ° C and treated with 8.5 g of ERLC wax (one triglyceride having chain lengths of the fatty acids included from C18 to C36) and dissolved in the mixture.
  • the solution is allowed to cool with vigorous stirring. During cooling, part of the wax separates from the solution and is emulsified in the mixture.
  • Silicon wafer surfaces can be printed.
  • the paste is made with the help of a0
  • the printed wafers are then heated to 400 ° C
  • FIG. 8 shows the micrograph of a line screen-printed with a doping paste according to Example 6, and dried.

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Abstract

L'invention concerne une nouvelle pâte imprimable se présentant sous la forme d'un gel hybride à base de précurseurs d'oxydes inorganiques, et apte à être utilisée dans un procédé simplifié destiné à la fabrication de cellules solaires, le gel hybride selon l'invention fonctionnant aussi bien comme milieu dopant que comme barrière de diffusion.
EP16711776.1A 2015-04-15 2016-03-24 Milieux dopants, formant barrière à une diffusion parasitaire et imprimables, à base de sol-gel et destinés au dopage local de tranches de silicium Withdrawn EP3284110A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP15001071 2015-04-15
EP15180681 2015-08-12
PCT/EP2016/000516 WO2016165810A1 (fr) 2015-04-15 2016-03-24 Milieux dopants, formant barrière à une diffusion parasitaire et imprimables, à base de sol-gel et destinés au dopage local de tranches de silicium

Publications (1)

Publication Number Publication Date
EP3284110A1 true EP3284110A1 (fr) 2018-02-21

Family

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EP16711776.1A Withdrawn EP3284110A1 (fr) 2015-04-15 2016-03-24 Milieux dopants, formant barrière à une diffusion parasitaire et imprimables, à base de sol-gel et destinés au dopage local de tranches de silicium

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US (1) US20180062022A1 (fr)
EP (1) EP3284110A1 (fr)
KR (1) KR20170137837A (fr)
CN (1) CN107532300A (fr)
TW (1) TW201710185A (fr)
WO (1) WO2016165810A1 (fr)

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CN115224152B (zh) * 2021-03-31 2024-04-16 浙江爱旭太阳能科技有限公司 太阳能电池及其制作方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19910816A1 (de) * 1999-03-11 2000-10-05 Merck Patent Gmbh Dotierpasten zur Erzeugung von p,p+ und n,n+ Bereichen in Halbleitern
EP2683777A2 (fr) 2011-03-08 2014-01-15 Merck Patent GmbH Barrière de métallisation à base d'oxyde d'aluminium
MY165641A (en) 2011-03-08 2018-04-18 Merck Patent Gmbh Formulations of printable aluminium oxide inks
JP6043302B2 (ja) 2011-03-08 2016-12-14 メルク パテント ゲゼルシャフト ミット ベシュレンクテル ハフツングＭｅｒｃｋ Ｐａｔｅｎｔ Ｇｅｓｅｌｌｓｃｈａｆｔ ｍｉｔ ｂｅｓｃｈｒａｅｎｋｔｅｒ Ｈａｆｔｕｎｇ 酸化アルミニウムペーストおよびその使用方法
JP5842931B2 (ja) * 2012-01-10 2016-01-13 日立化成株式会社 太陽電池用基板の製造方法
WO2013125252A1 (fr) * 2012-02-23 2013-08-29 日立化成株式会社 Composition de formation de couche de diffusion d'impureté, procédé de fabrication d'un substrat semi-conducteur doté d'une couche de diffusion d'impureté et procédé de fabrication d'un élément de cellule solaire
US9306087B2 (en) * 2012-09-04 2016-04-05 E I Du Pont De Nemours And Company Method for manufacturing a photovoltaic cell with a locally diffused rear side
US10134942B2 (en) * 2012-12-28 2018-11-20 Merck Patent Gmbh Doping media for the local doping of silicon wafers
JP2016506631A (ja) * 2012-12-28 2016-03-03 メルク パテント ゲゼルシャフト ミット ベシュレンクテル ハフツングＭｅｒｃｋ Ｐａｔｅｎｔ Ｇｅｓｅｌｌｓｃｈａｆｔ ｍｉｔ ｂｅｓｃｈｒａｅｎｋｔｅｒ Ｈａｆｔｕｎｇ シリコンウェハの局所ドーピングのための液体ドーピング媒体

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Publication number Publication date
US20180062022A1 (en) 2018-03-01
TW201710185A (zh) 2017-03-16
CN107532300A (zh) 2018-01-02
KR20170137837A (ko) 2017-12-13
WO2016165810A1 (fr) 2016-10-20

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