WO2016150548A2 - Barrière antidiffusion et antialliage pâteuse imprimable pour la fabrication de cellules solaires cristallines au silicium à haut rendement - Google Patents

Barrière antidiffusion et antialliage pâteuse imprimable pour la fabrication de cellules solaires cristallines au silicium à haut rendement Download PDF

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WO2016150548A2
WO2016150548A2 PCT/EP2016/000370 EP2016000370W WO2016150548A2 WO 2016150548 A2 WO2016150548 A2 WO 2016150548A2 EP 2016000370 W EP2016000370 W EP 2016000370W WO 2016150548 A2 WO2016150548 A2 WO 2016150548A2
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aluminum
silicon
titanium
tin
printable
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PCT/EP2016/000370
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German (de)
English (en)
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WO2016150548A3 (fr
Inventor
Oliver Doll
Ingo Koehler
Bilge GUENDUEZ
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Merck Patent Gmbh
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
    • B01J13/0052—Preparation of gels

Definitions

  • the present invention relates to a printable hybrid gel useful for making electronic passivation layers
  • the invention comprises the preparation and use of the paste according to the invention.
  • 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. It can instead, other alcohols of higher vapor pressure or higher boiling point than isopropyl alcohol may be added, provided that the 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 thoroughly cleaned with water and treated with dilute hydrofluoric acid to prepare the chemical oxide layer layer resulting therefrom, as well as adsorbed and adsorbed therefrom, to prepare the following
  • 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 P2O5) 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
  • BSG borosilicate glass
  • Dopant sources eg, boron oxide and boron nitride
  • 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
  • Nitrogen dry air, a mixture of dry oxygen and dry nitrogen and / or, depending on the design of the furnace to be passed, zones of one and the other of the above
  • 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 that can be applied in the context of the doping process: 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 ⁇ tzäauer and 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 concentrations of the hydrofluoric acid used. After etching, the wafers are rinsed with water.
  • the etching of the glasses on the wafer surfaces can also take place 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 respective process tanks horizontally (in-line system).
  • the wafers are conveyed on rolls and rolls either through the process tanks and the etching solutions contained therein, or the etching media are conveyed onto the wafer surfaces by means of roll 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 case of the
  • the concentration of hydrofluoric acid is typically 5%.
  • the pool temperature may be slightly elevated compared to the room temperature (> 25 ° C ⁇ 50 ° C).
  • edge insulation -> glass etching it has become established to carry out the so-called edge isolation sequentially simultaneously, which results in a slightly modified process flow: edge insulation -> glass etching.
  • 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.
  • the wafers are guided on one side via an 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 transported via rollers mediated on the back of the wafer.
  • the etching removal typically achieved with these methods amounts to approximately 1 ⁇ m silicon (including the glass layer present on the surface to be treated).
  • the glass layer still present on the opposite side of the wafer serves as a mask, which exerts some protection against etching attacks on this side. This glass layer is subsequently using the already
  • 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 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 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 evident in the wavelength range
  • the directional and non-directional reflection shows a value of about 1% to 3% of the originally incident light (vertical incidence to the surface normal of the silicon wafer).
  • the above-mentioned silicon nitride films are currently deposited on the surface generally by direct PECVD method. For this purpose, a gas atmosphere of argon is ignited a plasma, 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 silica, borosilicate glass and lead oxide and / or bismuth oxide.
  • the glass frit basically fulfills two functions: on the one hand, it serves as a bonding agent between the wafer surface and the mass of the On the other hand, it is responsible for the penetration of the silicon nitride cap layer to allow direct ohmic contact with 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 dried at temperatures of about 200 ° C to 300 ° C 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 binder, 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 front electrode grid consists of thin fingers
  • the typical height of the printed silver elements is usually between 10 pm and 25 pm.
  • the aspect ratio is rarely greater than 0.3, but can be significantly increased by the choice of alternative and / or adapted metallization.
  • alternative metallization is the
  • Customized metallization processes are based on two consecutive screen printing processes, optionally with the composition of two distinctive metal pastes (dual-print or print-on-print).
  • dual-print or print-on-print can be used with so-called floating buses, which ensures the removal of the current of the charge carrier collecting fingers, however, do not contact the silicon crystal itself directly ohm'sch.
  • 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 ⁇ 1mm is printed.
  • the paste is> 80% off
  • Aluminum assembled The remaining components are those that have already been 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
  • c is 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 pn junction is severed by means of the energy injected by this beam.
  • This trench with a depth of up to 15 pm as a result of Action of the laser generated. This silicon is over a
  • this laser trench is 30 pm to 60 pm wide and about 200 pm away from the edge of the solar cell.
  • solar cell architectures with both n-type and p-type base material include, among others
  • Elements of the cell consist of the front electrode grid, which Carrier removed from the cell via an external circuit.
  • the so-called emitter Connected directly to the electrode grid is the so-called emitter, which collects the charge carriers (electrons and holes) generated by the incidence of light and finally as a result of its absorption.
  • these are the electrons, insofar as one assumes the currently still prevailing technology of producing solar cells with a p-type base.
  • the emitter makes it possible to generate the electrons generated in the bulk of the silicon, the base or, more simply, the absorber (in this case, minority finite carriers with a short finite lifetime, the latter in the range of a few to a few hundred
  • the back of the base of standard aluminum BSF cells has a highly doped p-type zone, the back side field. This highly doped zone acts on the electrons generated in the base comparable to a kind of mirror: they are in this region due to the rising gradient of the
  • Mixture consisting of aluminum and silicon, aluminum, which with
  • Silicon crystal which consists of diffused aluminum.
  • This zone can have thicknesses in the range of 6 pm to 8 pm. In addition to the "reflection" of the electrons, this zone collects the holes, which then fictitiously vary across the backface field to the adjacent ones
  • FIG. 1a shows a schematic, unscaled cross-section through a standard aluminum BSF solar cell (rear bus buses not
  • Figure b shows a schematic, non-scaled cross-section through a J Q PERC solar cell (rear bus not shown).
  • the PERC cell is now a further development of this standard aluminum BSF cell in such a way that the one on the back of the
  • a dielectric is added, which is in this case between the silicon crystal and the printed aluminum. This dielectric layer is opened locally to allow contacting of the silicon with the aluminum paste. This local
  • the back dielectric has at least two important functions when used to make PERC solar cells: 1). She is responsible for the electronic surface passivation of the
  • This dark current can be thought of as a parasitic current that is due to the absorption of the photocurrent the sun's radiation is oriented opposite.
  • Short-circuit current density takes into account. This results partly from the previously sketched. Furthermore, and this is the second important function of the dielectric passivation layer, it acts on the back of the solar cell as an optical mirror and thus improves u. a. the backside reflectivity within the solar cell. Light which is able to penetrate the silicon of the solar cell is better reflected at the silicon dielectric interface than at the aluminum interface. This is the case for long-wave radiation ( ⁇ > 900 nm). Silicon has a relatively low level of indirect semiconductor
  • Absorption length can increase so much until the light can completely radiate through the thickness of a wafer (see Figure 2).
  • FIG. 2 shows the wavelength-dependent transmission of a polished silicon wafer (280-1100 nm) covered on the front side with 80 nm SiNx, calculated using the transfer matrix method.
  • Thickness of the silicon wafer was based on 180 pm of the calculation.
  • the transmission of the wafer is 1% at a wavelength of 925 nm.
  • the surface in the case of CZ wafers, the surface is characterized by irregularly arranged pyramids whose side faces enclose an angle of 54 ° with the fictitious planar silicon surface. This results in the case of perpendicular light incidence to the fictitious planar silicon surface between the light beam and the pyramid side surface
  • the reflectivity at the silicon-silicon dioxide interface is significantly higher than in the case of the interface silicon-aluminum. Due to the higher reflectivity of the silicon-silica interface, light beams can be reflected more efficiently at this interface
  • FIG. 3 shows the calculated reflectivity of the silicon-silicon dioxide interface as a function of the wavelength and the angle of incidence for a polished silicon wafer. The calculation was carried out by means of the transfer matrix method (280-1100 nm). Light of wavelengths significantly smaller than 800 nm is at a typical thickness of a
  • Silicon wafer for example, 180 pm or less, the silicon-silicon dioxide interface due to its complete absorption in the
  • FIG. 4 shows the calculated reflectivity of the silicon-aluminum interface as a function of the wavelength and the angle of incidence for a polished silicon wafer. The calculation was carried out by means of the transfer matrix method (280-1100 nm). Light of wavelengths much smaller than 800 nm is at a typical thickness of a silicon wafer, of
  • the silicon-aluminum interface can not reach as a result of its complete absorption in the silicon.
  • the refractive indices and the absorption coefficients of aluminum certainly do not correspond to those of a conventionally screen-printed and fired aluminum screen printing paste.
  • the back side of the silicon solar cell is normally characterized by the following further regions / phases before the transition to aluminum takes place: highly doped BSF zone, eutectic aluminum-silicon phase.
  • FIG. 5 shows a representation of the absorption of aluminum calculated using the transfer matrix method in the following test structure: SiNx (80 nm) / Si (180 ⁇ m) / Al (40 ⁇ m).
  • the angle of incidence on the test structure was 0 ° (parallel to the surface normal)
  • the wavelength range was 280 nm to 1100 nm.
  • the regions / phases present on the back were neglected: highly doped BSF zone eutectic aluminum-silicon phase.
  • the dielectric interlayer is not exclusive to the
  • Reflectivity at the interface silicon-silicon dioxide ultimately contributes to an increase in the short-circuit current density and thus to an increase in the efficiency of the solar cell (see model calculations in Table 1).
  • Table 1 Test structures calculated for different solar cells using the transfer matrix method. For the calculation, a polished Siiiziumwafer is assumed, the angle of incidence on the test structure is 0 ° (parallel to the surface normal), the wavelength range covers 280 nm to 1100 nm (804.60 W / m 2 ). It indicates the absorbed power in each layer as well as its contribution to the power radiated over the entire wave range. The power absorbed in the silicon wafer is converted into a maximum photocurrent to be achieved. The calculation does not take into account deviations from the perpendicular radiation incidence, ie effects which result from the surface texture of the solar cell. In practice, a higher differential of the
  • Short circuit current density between the two cells expected. It can be up to 0.5 mA / cm 2 (here: 0.13 mA / cm 2 ).
  • the dielectric on the wafer back side consists of more than one layer, but rather of a layer stack. Most are two layers, of which the first layer is directly on the wafer surface
  • This layer usually has a small thickness of a few (5 - 10 nm) manometers. Since such thin layers the metallization process with the Alumiumpaste, speak their Einlegierung, im As a rule, they can not resist, but are melted down and absorbed in the aluminum, and, as a result, their passivating effect naturally becomes obsolete
  • Passivation layers covered by at least one other capping layer whose layer thickness is several times greater than that of the actual passivation layer itself.
  • These capping layers must on the one hand be resistant enough to withstand the alloying process with the aluminum paste, and on the other hand they must
  • Aluminum paste ensure adequate adhesion.
  • the typical thickness of these capping layers is between 70 nm and 200 nm.
  • the use of the capping material has almost exclusively established that of SiNx, with the SiNx usually deposited on the passivation layer by means of PECVD methods becomes.
  • the passivation layers usually consist of S1O2, Al2O3, in some cases also of amorphous silicon (a-Si), and now and then the use of amorphous silicon carbide (a-SiC) has also been described.
  • the effect of the passivation layers on the deposited capping layer continues to benefit from the fact that hydrogen stored in the capping layer can be released to the dielectric passivation layer below it. This hydrogen can saturate the interface between silicon and passivation layer existing defect sites and thus passivate.
  • the production of a PERC solar cell thus comprises the following process steps in the context of the implications described above:
  • Metallization pressure and co-firing the deposition of the dielectric passivation layer as well as the capping material, as well as the wet-chemical texture and the wet-chemical polishing.
  • Numerous alternatives have been presented for the industrial standard, namely the metallization of the solar cell wafers with the aid of the screen printing process, which, however, have hitherto not been able to establish themselves in mass production due to cost reasons.
  • the metallization pressure is accordingly difficult to replace.
  • the texturing and polishing of the wafers can not be dispensed with because of the efficiency aspects of the future solar cell; with which the deposition of
  • Wafer surface generated Wafer surface generated.
  • the use of other alanes has also been described in the literature, but their distribution corresponds to far from that of trimethylalan.
  • Tin dioxide and titanium dioxide prepared on the basis of the sol-gel technique, which by screen printing or another
  • Solar cells preferably of so-called PERC solar cells, printed structured and subsequently dried, and then
  • the printable hybrid gel according to the invention can be prepared on the basis of precursors of the following oxide materials: a. Silicon dioxide: one to fourfold symmetric and asymmetric
  • the central silicon atom may have a degree of substitution of at least one hydrogen atom bonded directly to the silicon atom, such as, for example, triethoxysilane, and further wherein a degree of substitution refers to the number of possible carboxy and / or alkoxy groups present which are present in both alkyl and alkoxy groups. 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 b.
  • Alumina symmetrically and asymmetrically substituted
  • Aluminum alcoholates such as aluminum thiocyanate
  • Tin (II, IV) oxide tin alkoxides, such as tin tetraisopropylate and tin tetrabutate, tin carboxylates, such as tin diacetate, tin oxalate, Tin tetraacetate, alkyltin carboxylates such as dibutyltin diacetate,
  • Titanium dioxide titanium alkoxides, such as titanium ethoxide,
  • the said precursors and their mixtures either under hydrous or anhydrous conditions by means of the sol-gel technique are brought either simultaneously or sequentially to partial or complete intra- and / or interspecific condensation, and due to the set condensation conditions, such as precursor concentrations , Water content, catalyst content, reaction temperature and time, the addition of condensation-controlling agents, such as various of the above complex and chelating agents, various solvents and their individual volume fractions, as well as the targeted elimination of volatile reaction aids and disadvantageous - by-products, the degree of gelation of the resulting hybrid gels targeted control and desirably influence, so that
  • the printable hybrid gel according to the invention can be influenced by the choice of suitable reaction conditions with respect to its degree of condensation in that it is in the form of a highly viscous mixture which is suitable for such mixtures, generally expressed as pasty formulations or pastes, suitable printing process, preferably the screen printing process, can be processed and applied to substrates in the manner already claimed.
  • suitable printing process preferably the screen printing process
  • the Hybrid gel may additionally contain polymeric thickeners and inorganic particulate additives, such as SnO 2, SiC, BN, Al 2 O 3, SiO 2, AbTiO 2, TiO 2, TiC, S 13 N 4, TiN and TixCyNz to positively influence the
  • the printable hybrid gel is a paste which is preferably structured by means of screen printing
  • the printable hybrid gel which can be produced exclusively on the basis of oxide precursors of the tin dioxide and the aluminum oxide, can be printed on the silicon surface and dried and acts both electronically surface passivation and as a barrier
  • the printable hybrid gel of the present invention is prepared solely on the basis of oxide precursors of silica, alumina, and titania, and is printed and dried on the silicon surface as described above, and functions both as an electronic surface passivation agent and as a barrier to alloying and diffusion Aluminum in the underlying silicon under the layer.
  • it is a printable hybrid gel which improves and increases the internal backside reflectivity in a solar cell, preferably of so-called PERC solar cells, the reflectivity being in many areas according to the concentration ratios of the primary to the latter Production of used oxide precursors can be set specifically. It is therefore a printable hybrid gel, which after drying on a silicon wafer surface, or generally on a surface, an electrically insulating barrier layer between two electrical
  • MEMS microelectronic and microelectromechanical
  • TFT thin-film transistors
  • LCD liquid crystals
  • OLED organic light-emitting diodes
  • touch-sensitive capacitive and resistive sensors based on the technologies of thin-film transistors (TFT), liquid crystals (LCD), organic light-emitting diodes (OLED) and touch-sensitive capacitive and resistive sensors.
  • TFT thin-film transistors
  • LCD liquid crystals
  • OLED organic light-emitting diodes
  • touch-sensitive capacitive and resistive sensors touch-sensitive capacitive and resistive sensors.
  • hybrid gels consisting of mixtures of precursors of silicon dioxide, aluminum oxide,
  • the low-viscosity formulations which should refer to a randomly selected limit of the dynamic viscosity of ⁇ 100 mPa * s low viscosity, as inks
  • pastes highly viscous formulations, ie those whose dynamic viscosities are then consistently above the aforementioned limit of 00 mPa * s, be referred to as pastes.
  • the hydride sols and gels can be alkoxides of the aforementioned
  • Classes of compounds (pecursors of silica, alumina,
  • Tin oxides, tin dioxides, titanium dioxide in arbitrary proportions, however, this does not necessarily have to.
  • Hybrid sols and gels may contain other substances that can impart advantageous properties to the sols and gels. They may be: oxides, basic oxides, hydroxides, alkoxides, carboxylates, ⁇ -diketones, ⁇ -ketoesters, silicates and the like of cerium, zirconium, hafnium, zinc, germanium, gallium, niobium, yttrium, boron and phosphorus, which are known in the art Sol-gel synthesis can be used directly or pre-condensed. The hydride sols and gels can be prepared with the help of pressure and
  • Coating methods on the surface of electronically passivated silicon wafers or the silicon wafer surfaces are applied.
  • Suitable methods for this may 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, Päd Printing or Rotary Screen Printing.
  • the printing of the hybrid gels is accomplished by screen printing.
  • the hybrid gels printed on the surface of electronically passivated silicon wafers or the silicon wafer surface become one after their deposition
  • This drying may, but not necessarily, be done in a continuous furnace. In the drying of gels, these are due to the spewing of solvents, as well as the thermal degradation of formulation excipients and the
  • This drying can be achieved at temperatures up to 600 ° C, but preferably from 200 ° C to 400 ° C.
  • temperatures up to 600 ° C, but preferably from 200 ° C to 400 ° C.
  • Silicon wafer surfaces printed and dried layers can be applied over the entire surface in this process. After drying, these layers resist the alloying of aluminum paste, which in turn is printed on these layers and then compacted and sintered during the co-firing process. During this process, the printed layer of the hybrid gels may be another Drying or compaction subject.
  • the printed layer of the hybrid gels may be another Drying or compaction subject.
  • Hybrid gels are applied to the surface of electronically passivated silicon wafers or the silicon wafer surface using a patterned screen found to be suitable during screen printing.
  • the structured sieve preferably has the structural features that are important for the subsequent contact formation of the aluminum paste with the silicon wafer: that is, omissions are to be generated in the
  • structured printing of the barrier layer eliminates the step of local contact opening, as in the case of deposition of the dielectric layer
  • Passivation and capping layer is necessary. An electronic surface passivation already present under the barrier layer is removed from the alloy during the contact-forming step
  • the barrier layer which can be printed on the basis of hydride gels is also able to passivate the silicon surface electronically, the deposition of the dielectric passivation layer can thus be dispensed with.
  • the hybrid gels can be prepared using anhydrous as well as hydrous sol-gel synthesis. As further auxiliaries in the formulation of the gels, the following substances can be used advantageously:
  • particulate additives eg aluminum hydroxides and
  • Aluminas colloidally precipitated or fumed silica
  • oxides • oxides, hydroxides, basic oxides, acetates, alkoxides, silicates
  • Polyvinylpyrrolidone hydroxyethylcellulose, methyl and ethylcellolose, polyacrylates and polyacrylic acids, polyvinyl alcohol, polyvinyl acetate, polyvinyl isobutyrate and others.
  • a Method to prepare a suitable paste according to the invention the pre-dissolving of a silica precursor, such as tetraethyl orthosilicate, in a solvent or solvent mixture, preferably selected from the group of high boiling glycol ethers or preferably high boiling glycol ethers and alcohols.
  • a solvent or solvent mixture preferably selected from the group of high boiling glycol ethers or preferably high boiling glycol ethers and alcohols.
  • water and acetic acid or alternatively preferably to be used carboxylic acid, are added in the required amount, after which the mixture is refluxed for three hours at temperatures between 100 ° C and 130 ° C.
  • the precondensed solution of the silica precursor is then, in the case of an advantageous use of titanium dioxide precursors, with tetraethyl orthotitanate, which in turn preferably dissolved in one or a mixture of high-boiling glycols, glycol ethers and or a mixture of high-boiling glycols and / or glycol ethers and an alcohol is, the pre-condensed
  • Chelating agents such as 1,3-cyclohexanedione and 3,5- Dihydroxybenzoic acid, as well as possibly added further desired amount and dissolved therein until a completely clear and transparent solution is obtained.
  • the reaction mixture may also first be treated with a suitable alumina precursor, such as aluminum tri-sec-butoxide, and only after its addition with the complex already mentioned above and chelating agents are further completed.
  • alumina precursor is advantageously in a, the rheology and printability of the final formulation positively affecting solvent, such as
  • Components can, for example, while Refluxierens under
  • the rheology and printability advantageously influencing auxiliaries, such as different polyvinylpyrrolidone, different ethyl or methylcelluloses or substances already mentioned above, as well as by the additional use of other particulate, the rheology also advantageously influencing additives such Aluminum hydroxides and aluminum oxides, colloidally precipitated or finely divided silica, tin dioxide, boron nitride, silicon carbide, silicon nitride, aluminum titanate, titanium dioxide, titanium carbide, titanium nitride or titanium carbonitride, can furthermore be tuned and influenced in the desired manner.
  • auxiliaries such as different polyvinylpyrrolidone, different ethyl or methylcelluloses or substances already mentioned above, as well as by the additional use of other particulate
  • the rheology also advantageously influencing additives such Aluminum hydroxides and aluminum oxides, colloidally precipitated or finely divided silica, tin dioxide, boron nitride,
  • Paste formulation of said additives no advantageous use may be required to add the tin oxide precursors either at the end of the reaction regime in the gelled paste, or in connection with the addition of the alumina precursors of the mixture and thus to incorporate into the hybrid gels.
  • An alternative method of synthesis based on the same solvents and solvent mixtures as already explained in more detail above, and reactants to be used at the outset, such as, for example, water and acetic acid and the like, comprises the simultaneous addition of
  • desired oxide precursors such as those of silica, alumina, titania and tin oxide
  • ⁇ -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, oximes and other such cited compounds, as well as any mixtures of aforementioned complex, chelating agent and the degree of condensation
  • the volatile and desired parasitic by-products which occur in this type of reaction are removed from the finished reaction mixture by means of vacuum distillation.
  • the vacuum distillation is carried out according to the conditions already explained above.
  • the hybrid gels are then by targeted addition of suitable and the rheology and printability of the paste favoring solvents with respect to their desired
  • Paste rheology may, but does not necessarily have to, be adjusted and rounded according to specific requirements in accordance with and with the auxiliaries and additives also described in detail above.
  • Thickener solvent is removed again on a rotary evaporator.
  • the screen-printable paste is printed on ⁇ 100> CZ, alkaline-textured, n-type silicon wafers.
  • a 280 mesh "1 mesh stainless steel screen with a 25 micron thread thickness and an ISAR thickness of 12 microns is used as a squeegee with a Shore hardness of 85, which is clamped at an angle of 35 degrees It is printed at a speed of 70 mm / s, a squeegee pressure of 1, 1 bar and a jump of 1 mm, the layout is a 5 x 5 cm square and after printing, the wafers at 100 ° C for Pre-dried for 5 min on a standard laboratory hotplate
  • Example 2 10 g of EGB, 4.08 g of TEOS and 3.6 g of acetic acid are mixed, and a mixture consisting of 0.75 g of water and 5 g of EGB is added thereto
  • Example 3 7.5 g of EGB, 0.36 g of water, 2.04 g of TEOS and 1, 8 g of acetic acid are mixed, refluxed at 130 ° C for 3h. Thereafter, 4.56 g of TEOT are diluted by adding 5 g of EGB and are refluxed for an additional 1 hour. To the reaction mixture are added 30 grams of Texanol, 1.54 g of 3,5-dihydroxybenzoic acid, and 1.12 g of 1,3-cyclohexanedione, and the entire mixture is further refluxed until a clear solution is formed, followed by 5 g EGB dissolved 4.93 g of ASB were added by slowly dripping.
  • reaction mixture is diluted by addition of a further 12.5 g of EGB and refluxed for 1.5 h, during which reaction volatile by-products are distilled off with the aid of the water separator. After the reaction, 1.47 g of ethyl cellulose dissolved in ethanol are homogenized in the paste. The still contained ethanol is then removed by distillation on a rotary evaporator.
  • This approach provides a printable paste with a viscosity between 8 Pa * s to 9 Pa * s
  • Dibutyltin diacetate, 4.51 g of PVP K30 and 0.55 g of SiC are successively stirred into the paste and homogenized in each case.
  • the paste is polished on one side ⁇ 100> CZ silicon wafer using a
  • the coated layers are dried at 400 ° C. for 10 minutes on a laboratory heating plate, and the layer thickness of the films is determined using a surface profilometer. With a wet film application of 50 ⁇ m, a dried, stress-crack-free layer thickness of the glass film of 1260 nm is achieved.
  • the paste is printed on glossy etched CZ wafers and single-sided polished CZ wafers. Screen printing uses four different screens whose properties are listed in Table 2.
  • Table 2 Sieving parameters of the screens used for screen printing of the inventive paste according to Example 4. A wafer printed using the screen 1 is shown in Figure 6.
  • Figure 6 shows the layout (center) printed on the glossy etched wafer with the screen 1 (according to Table 2). A line (right) and a
  • FIG. 7 shows a layout printed on a polished wafer with the aid of screen 2 (according to Table 2), which was dried on a hotplate for 10 minutes at 400 ° C. after printing.
  • the layer thickness was determined at one of the two squares at 612 nm, at the other at 550 nm using a surface profilometer.
  • the layer thickness of the thin lines (right in the picture) was 910 nm.
  • the resulting glass films are closed and have no stress cracks. After further annealing for 1 minute at 900 ° C, the films shrank in the order named to 490 nm, 360 nm and 675 nm. Even after annealing under elevated temperature, the glass films do not have any stress cracks.
  • the layout printed on a polished wafer surface using screen 3 (according to Table 2) consisted entirely of lines.
  • the one of the lines determined by means of a surface profilometer
  • a suitable paste formulation was also obtained using the following additives: 0.45 g a-SiNx, 0.55 g aluminum titanate, 2.47 g TiN, 0.55 g ZrSiO 4 , 0.55 g BN and 0.55 g AI2O3 in each case instead of SiC.
  • the remaining paste variants were doctored onto polished wafers with the aid of a stainless steel handrail and then dried at 400 ° C. for 10 minutes. Table 3 gives an overview of the layer thicknesses obtained with the pastes as well as the performance characteristics.
  • Table 3 Composition of the flow properties (measured with the program sequence mentioned under Example 4) of the different
  • Paste modifications according to Example 4 their applied wet film thicknesses and their drying resulting dry film thicknesses.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Photovoltaic Devices (AREA)
  • Silicon Compounds (AREA)

Abstract

La présente invention concerne un gel hybride imprimable servant à la fabrication de couches de passivation électroniques vis-à-vis de l'aluminium. L'invention concerne en outre la fabrication et l'utilisation de la pâte selon l'invention.
PCT/EP2016/000370 2015-03-23 2016-03-03 Barrière antidiffusion et antialliage pâteuse imprimable pour la fabrication de cellules solaires cristallines au silicium à haut rendement WO2016150548A2 (fr)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113990985A (zh) * 2021-11-02 2022-01-28 南京日托光伏新能源有限公司 铸锭单晶加mwt电池结构的制备方法
CN115910425A (zh) * 2022-12-07 2023-04-04 苏州晶银新材料科技有限公司 一种用于N型TOPCon太阳能电池的正面银铝浆及其制备方法
US11993831B1 (en) 2020-12-18 2024-05-28 Lockheed Martin Corporation Printable high-strength alloys

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050247915A1 (en) * 2002-09-06 2005-11-10 Koninklijke Philips Electronics N.V. Compound for screen-printing, screen-printed layer and substrate provided with such layer
CN1328343C (zh) * 2002-09-06 2007-07-25 皇家飞利浦电子股份有限公司 用于网板印刷的化合物,网板印刷层和带有该层的基底
JP6059155B2 (ja) * 2011-03-08 2017-01-11 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 印刷可能な酸化アルミニウムインクの処方物
KR101929183B1 (ko) * 2011-03-08 2019-03-14 메르크 파텐트 게엠베하 알루미늄 옥시드 페이스트 및 그의 사용 방법
EP2938760A1 (fr) * 2012-12-28 2015-11-04 Merck Patent GmbH Substances de dopage liquides destinées au dopage local de tranches de silicium
EP2938761A1 (fr) * 2012-12-28 2015-11-04 Merck Patent GmbH Substances de dopage destinées au dopage local de tranches de silicium
US20150340518A1 (en) * 2012-12-28 2015-11-26 Merck Patent Gmbh Printable diffusion barriers for silicon wafers
WO2014101988A1 (fr) * 2012-12-28 2014-07-03 Merck Patent Gmbh Substances d'oxydes destinées à extraire par effet getter des impuretés de tranches de silicium

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11993831B1 (en) 2020-12-18 2024-05-28 Lockheed Martin Corporation Printable high-strength alloys
CN113990985A (zh) * 2021-11-02 2022-01-28 南京日托光伏新能源有限公司 铸锭单晶加mwt电池结构的制备方法
CN115910425A (zh) * 2022-12-07 2023-04-04 苏州晶银新材料科技有限公司 一种用于N型TOPCon太阳能电池的正面银铝浆及其制备方法

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