EP2013379A2 - Procédé de purification d'un matériau semi-conducteur par application d'une réaction d'oxydo-réduction - Google Patents

Procédé de purification d'un matériau semi-conducteur par application d'une réaction d'oxydo-réduction

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Publication number
EP2013379A2
EP2013379A2 EP07747296A EP07747296A EP2013379A2 EP 2013379 A2 EP2013379 A2 EP 2013379A2 EP 07747296 A EP07747296 A EP 07747296A EP 07747296 A EP07747296 A EP 07747296A EP 2013379 A2 EP2013379 A2 EP 2013379A2
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EP
European Patent Office
Prior art keywords
electrolyte
cathode
anode
silicon
compounds
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Application number
EP07747296A
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German (de)
English (en)
Inventor
Uwe Hermann Dobberstein
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GIRASOLAR BV
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GIRASOLAR BV
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Publication of EP2013379A2 publication Critical patent/EP2013379A2/fr
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
    • C25C3/24—Refining
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/33—Silicon
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/26—Electrolytic production, recovery or refining of metals by electrolysis of melts of titanium, zirconium, hafnium, tantalum or vanadium
    • C25C3/28—Electrolytic production, recovery or refining of metals by electrolysis of melts of titanium, zirconium, hafnium, tantalum or vanadium of titanium

Definitions

  • the present invention relates to a method for the purification of a semiconductor material by application of an oxidation-reduction reaction.
  • Silicon is one of the best known and most applied semiconductor materials and is often applied in the industry, such as for example in solar cells, diodes, transistors, integrated circuits (chips) and other areas of electronics.
  • a high purity or silicon is required, such as for example so-called SoG silicon (Solar Grade, purity of > 99.9999% (> 6N)) or EG silicon (Electronic Grade, purity of > 99.9999999% (> 9N)).
  • So-called MG silicon Metallurgic Grade, purity of 98 - 99%
  • Such silicon materials are generally obtained from SiO 2 (for example, sand) by reduction with carbon (C) under formation of carbon mono oxide (carbothermal reduction).
  • impurities that may be present in MG silicon are carbon, boron or phosphorus compounds and metallic elements, such as for example iron, aluminium, titanium and vanadium.
  • impurities cause a deterioration of the semiconductor properties of the material, which for example may lead to a reduced yield for solar cells.
  • deteriorated semiconductor properties are also undesirable for other electronics applications.
  • Certain impurities such as for example iron, aluminium, boron, phosphorus, titanium and vanadium are more deleterious than others and in addition, certain impurities are more difficult to remove from silicon than others.
  • the simplicity of removal is related to, among other things, the separation coefficient or the difference in solubility of a certain element in fluid and solid silicon.
  • the standard process for the purification of silicon that is currently applied consists of a number of steps, namely a first step in which MG Si is chlorinated with HCI gas to 90% SiHCI 3 (trichloro silane) and 10% SiCI 4 (silicon tetrachloride) during which process hydrogen gas is formed.
  • the newly formed silicon compounds in the gas phase are purified by means of fractional distillation until the quantity of impurities reaches the ppb (parts per billion) and ppm (parts per million) level.
  • the so-called 'Siemens process' deposition of purified silicon takes place by application of the purified gaseous silicon compounds and hydrogen. This reaction is carried out at a temperature of for example 900-1100 0 C on an electrically heated graphite electrode to form polycrystalline silicon of a purity of 99.99999% (7N) and HCI.
  • a similar method for the purification of silicon is disclosed in US patent 4,213,937.
  • JP 06/173064 discloses a method for the electrolytic purification of titanium by means of electrolysis in molten salts.
  • WO 02/099166 discloses a method for making silicon by dissolution of SiO 2 in an electrolyte consisting of CaCI 2 and CaO.
  • the method comprises the steps of: a) the oxidation of an anode placed in an electrolyte and made of a semiconductor material containing one or more impurities, one or more ionic compounds being present in the electrolyte, and the ionic compounds reacting with the semiconductor material and the one or more impurities, to form one or more compounds according to formula I:
  • the present invention will be further explained on the basis of silicon as example of a semiconductor material; however, the present invention is also applicable to other semiconductor materials such as for example germanium.
  • Figure 1 is a schematic representation of a configuration that has been applied to carry out the method according to the present invention
  • Figure 2 is a schematic representation of an electrolytic cell that can be applied for carrying out methods according to the present invention
  • Figure 3 is representation of a cyclic voltammogram
  • Figure 4 is a SEM-EDX graph
  • Figure 5 is a SEM-EDX graph.
  • the present invention provides an energy-efficient method by carrying out a first reaction (step a according to the present method) at an anode and the second reaction (step b according to the present invention) at a cathode.
  • the electrons that are formed at the anode are used at the cathode as a result of which, in principle, no additional energy is required, as a reversible (equilibrium) reaction is used.
  • the supply of additional energy by increasing the electrical difference of potential can accelerate the reaction significantly.
  • a further advantage of the present invention is that HCI gas and hydrogen gas are no longer required, as ionic compounds, such as for example chlorine ions or other ions, can be applied instead of gaseous compounds. These ionic compounds will react with the semiconductor material of the anode to form the compounds according to formula I, such as for example halogenated silicon compounds if a silicon anode is applied.
  • ionic compounds such as for example chlorine ions or other ions
  • these ionic compounds will react with the semiconductor material of the anode to form the compounds according to formula I, such as for example halogenated silicon compounds if a silicon anode is applied.
  • the one or more impurities present in the semiconductor material to be purified react in one or more reactions with the one or more ionic compounds to form the associated reaction products.
  • Such associated reaction products if MG-Si is applied as anode, are for example FeCI 3 , PCI 3 , BCI 3 , TiCI 4 ,
  • the electrolyte serves as transport medium for the ionic reaction products from the cathode to the anode. Returning these ionic reaction products therefore preferably takes place through the electrolyte.
  • the addition to the cathode of the one or more compounds according to formula I can for example take place by bubbling such compounds as a gas at the cathode. However, other methods can also be applied.
  • Figure 1 shows an example of a configuration 1 which was used by the present inventors for carrying out the method according to the present invention.
  • Figure 1 displays a syringe pump 2, connected to an evaporation device 3, this evaporation device 3 being connected to an electrolytic cell 4.
  • a cathode 5 and an anode 6 are present in the electrolytic cell 4, displayed in Figure 1. Ion exchange takes place between the cathode 5 and the anode 6, displayed in Figure 1 by an arrow next to which Cl " is written.
  • step a) of the present method one or more ionic compounds are formed at the anode 6 and are collected (see arrow at anode 6). These compounds are subsequently purified externally.
  • the purified desired silicon compounds are subsequently supplied to the cathode for carrying out step b) of the present method, by application of the syringe pump 2. Any unreacted silicon compounds are drained off in the form of gas at the top of cathode 5 (see arrow at cathode 5).
  • FIG 2 is an embodiment of an electrolytic cell applicable in the present invention.
  • This preferred embodiment of the electrolytic cell 4 consists of a quartz tube 7 which is closed on one end and which is partly filled with electrolyte 8.
  • Two quartz tubes 9 having open lower ends are placed in this electrolyte 8.
  • the anode 6 and the cathode 5, respectively, have been placed in these quartz tubes.
  • a quartz tube with a reference electrode 10 as well as a quartz tube with a thermo couple 11 to measure the temperature as well as a supply pipe for compounds in the form of gas.
  • step c) comprises two sub steps, c1 ) and c2), namely c1) the extraction of the one or more compounds according to formula I and the one or more associated reaction products from the electrolyte; c2) the separation of the one or more compounds according to formula I from the one or more associated products.
  • both the formed halogenated silicon compounds and the associated reaction products are extracted, preferably as gas, from the electrolyte in which the anode has been placed and are, after purification thereof, added to the cathode where reduction can take place to form silicon and ions (for example chlorine ions).
  • the ions preferably move, through the electrolyte, to the anode where they react with MG Si to form additional halogenated silicon compounds.
  • Such an embodiment of the present invention ensures excellent purification and prevents contamination of the electrolyte.
  • Impurities possibly present in the starting material such as for example boron and phosphorus, are removed before the purified halogenated silicon compounds result in pure silicon by deposition on the cathode.
  • the removal of boron and phosphorus is of great importance as these elements are applied as dopants in the further processing of pure silicon.
  • the quantity of such dopants should be determined very accurately to obtain the desired properties and therefore, it is of great importance that these elements are present in the purified silicon as little as possible.
  • Step c1 may for example be carried out by means of phase separation.
  • Halogenated silicon compounds are volatile at the applied temperatures and may therefore be collected as gases from the fluid electrolyte. Other extraction methods, however, may also be applied.
  • Step c2) may for example be carried out by means of fractional distillation.
  • the halogenated silicon compounds and the halogenated impurities possess different boiling points and may therefore be separated by means of distillation. Other separation methods, however, may also be applied.
  • step c2 the compounds according to formula 1 are separated in step c2) until they possess a purity of greater than or equal to 99.99%
  • silicon is applied as the semiconductor material in step a), and more specifically MG silicon, because of the good availability of the latter.
  • the material of the cathode is preferably selected from the group consisting of silicon, carbon, silver, molybdenum, platinum and tungsten and one or more combinations thereof.
  • other conducting materials are also applicable.
  • silicon and more specifically silicon of at least the desired purity that is, a purity of greater than or equal to 99.99% (4N) and preferably 99.9999% (6N), are preferred as cathode material.
  • Such materials give sufficiently good properties regarding electron conductance and are inert. These materials have a low resistance to electron conduction at the operating temperature, give minimum contamination of the silicon to be purified, minimum contamination of the electrolyte and contain surface sites with low activation energies for the simple crystallisation of silicon.
  • the advantage of the application of silicon as cathode material and more specifically of silicon of at least the desired purity is that it is simpler to remove the formed silicon from the cathode, for example by scraping it off, without formation of any impurities in the formed silicon because of also scraping off cathode material.
  • the anode material preferably consists of semiconductor material to be purified, where it is possible that the semiconductor material to be purified forms the entire anode, that is, that the anodes for example consist of a wire, rod or chunks of MG silicon. It is also possible that the anode consists of a core of an inert material, which serves as carrier, the inert material preferably not being a conductor for electrons, and the inert material being enclosed in a mantle of the semiconductor material. Such a mantle may for example be applied to the core by means of deposition, sputtering or coating.
  • the semiconductor material to be purified is porous or pulverulent.
  • the material to be purified possesses a large surface area, which increases the reaction rate.
  • two electrolytes are applied, more specifically an electrolyte in which the anode has been placed and an electrolyte in which the cathode has been placed. It is preferred that these electrolytes are identical. This makes the reactor design simpler as the anode and the cathode can be present in a single vessel. This also simplifies returning the ionic compounds from the cathode to the anode.
  • the electrolyte in which the cathode has been placed preferably meets the following requirements:
  • the electrolyte in which the anode has been placed preferably meets the following requirements:
  • electrolyte for example molten salts can be mentioned. It is preferred that the electrolyte is a salt of one or more halogens and one or more alkali (earth) metals or one or more combinations thereof, such as NaCI, KCI, LiCI 2 and BaCI 2 but also nitrates, carbonates and sulphates and combinations thereof or ionic fluids at room temperature can be mentioned as electrolyte.
  • electrolytes can be applied both as electrolyte in which the anode has been placed and as electrolyte in which the cathode has been placed.
  • a membrane is applied that is permeable to the one or more ionic compounds that are formed in step b).
  • the membrane is present between the electrolyte in which the anode has been placed and the electrolyte in which the cathode has been placed.
  • Such a membrane should be selectively permeable for the passage of ionic reduction compounds from cathode to anode and not to oxidation products from anode to cathode.
  • a membrane may prevent contamination of the electrolyte in which the cathode has been placed, such contamination possibly consisting of positively charged ions (metal and other) that may be deposited on the cathode and therefore contaminate the purified semiconductor material.
  • the membrane is preferably made of a ceramic material, such as for example La-M-O-Cl (M is alkali earth metal, such as for example Ca/Sr).
  • a ceramic material is an example of a so-called 'Solid Electrolyt' which is applied in fuel cells.
  • a capture electrode is applied which is connected to an external voltage source, the capture electrode having an equal or somewhat higher potential relative to the cathode, and the capture electrode having been placed in the electrolyte between the anode and the cathode.
  • the capture electrode is not exposed to the compounds according to formula I that are added to the cathode and the sole purpose of this capture electrode is to provide a site for precipitation and adherence of impurities (oxidation products) that are released at the anode.
  • impurities oxidation products
  • step c2 additionally one or more compounds according to formula I are added in step b) to compensate for any possibly observed losses during the purification according to step c2).
  • Such compounds should be of the desired purity, that is, a purity of at least 99.99% (4N) and more specifically at least 99.9999% (6N).
  • the conditions for carrying out the present reaction such as pressure, temperature and reduction potentials, are determined by the reaction rate of the anodic and cathodic reactions.
  • the minimum temperature for the precipitation of silicon around the electrode is circa 400 0 C caused by the conductive behaviour of silicon which increases with increasing temperature, as is usual in semiconductors.
  • the transition from amorphous to crystalline silicon occurs at a temperature of 470 0 C and therefore, the temperature at the cathode is preferably at least 400 0 C, more specifically at least 470 0 C.
  • amorphous silicon is formed at the cathode which for a certain temperature of the cathode, for example a temperature above 470 0 C, is subsequently converted to crystalline silicon.
  • amorphous silicon as such can also be applied.
  • Crystalline silicon can also be formed at a lower temperature ( ⁇ 400 0 C) by using the high resistance of silicon at low temperature, which leads to local heating of the cathode which leads to formation of crystalline silicon. If the resistance rises, the temperature will also rise and this will lead to an improved crystalline form of for example silicon. A higher resistance will, however, also lead to an increased energy usage which is disadvantageous. It is therefore of importance to find a good compromise.
  • the concentration of the compounds of formula I at the cathode should be as high as possible.
  • halogenated silicon compounds these are gaseous at the application temperature of at least 400 0 C because of their boiling points and therefore, the reaction will be carried out in three phases, namely solid (cathode), fluid (electrolyte) and gaseous (halogenated silicon compound).
  • the pressure should preferably be high to enable a high concentration of the compounds according to formula I.
  • the electrolyte should possess a surface tension as high as possible and the bubbles should be as small as possible to obtain an internal pressure as high as possible. This is because the internal pressure in a gas bubble is determined by the external pressure of the fluid and the surface tension divided by the radius of the bubble.
  • the conditions such as temperature and pressure should be adjusted accordingly.
  • Anodic reaction conditions It is desirable that all products that are formed at the anode are gaseous to limit contamination of the electrolyte to a minimum. Whether the products that are formed at the anode are gaseous depends on the temperature and pressure that are applied, in combination with the boiling points of such formed compounds. To obtain gaseous products, the boiling point of the formed compound should be lower than the temperature at which the reaction is carried out. For example, the boiling point is 57.6 0 C for the desired SiCI 4 which will be gaseous at the reaction temperature.
  • Examples of contaminants often present in MG Si that are gaseous at a reaction temperature of 400 0 C are the following: BCI 3 (12.5 “C), PCI 3 (75.95 0 C), TiCI 4 (136.4 0 C), PCI 5 (160 °C), AICI 3 (182.7 °C) and FeCI 3 (315 0 C).
  • BCI 3 (12.5 "C)
  • PCI 3 75.95 0 C
  • TiCI 4 136.4 0 C
  • PCI 5 160 °C
  • AICI 3 (182.7 °C)
  • FeCI 3 315 0 C
  • FeCI 2 which also often occurs in the reaction has a boiling point of 1026 0 C and thus will not be collectible as a gas at a temperature of 400 0 C and should therefore be removed by some other way.
  • a membrane or capture electrode is required.
  • an external voltage source which is not limited to a certain type, is applied to apply a difference of potential across the anode and the cathode, the difference of potential being selected between 0.01 V and the standard reduction potential of the electrolyte.
  • the reduction potential (E 0 ) of SiCI 4 is -1.451 V at 25 0 C and is -1.389 V at 850 0 C.
  • the reduction potential of a number of the previously mentioned electrolytes is as follows: MgCI 2 (-3.066 V at 25 0 C and -2.42 V at 850 0 C), CaCI 2 (-3.887 V at 25 0 C and -3.296 V at 850 0 C), NaCI (-3.982 V at 25 0 C) and KCI (-4.235 V at 25 0 C).
  • the applicability of electrolytes depends on the mobility of the ionic compounds in the electrolyte.
  • the electrolyte is forced to flow from the cathode to the anode and vice versa.
  • the electrolyte is led, at a particular rate, in a flow from the cathode and the anode, and in particular, the flow of the electrolyte from the anode to the cathode is physically separated from the flow of the electrolyte from the cathode to the anode.
  • This is, for example, possible by a closed loop whereby the electrolyte is forced to flow and where the anode and cathode have been placed in the closed loop at individual sites. More specifically, it is advantageous when a membrane or in particular a capture electrode has been placed between the anode and the cathode.
  • Such a circulation of the electrolyte may for example be realised by application of a pump or by application of a density difference.
  • a density difference may for example be realized by a temperature difference but also by the presence of gas bubbles (bubbling) at an electrode, such as the cathode.
  • gas bubbles bubbling
  • other methods for the realization of a circulation flow may also be applied.
  • the present method may be carried out by application of any suitable equipment or combinations thereof, such as for example a device for processing of MG silicon (crushing, leaching), an electrolytic cell (anode and cathode and electrolytes), a separation device for purification of halogenated silicon compounds (distillation, absorption, absorption, membrane separation) and a device for processing pure silicon (washing, crushing).
  • a device for processing of MG silicon crushing, leaching
  • an electrolytic cell anode and cathode and electrolytes
  • a separation device for purification of halogenated silicon compounds distillation, absorption, absorption, membrane separation
  • a device for processing pure silicon washing, crushing
  • a configuration was applied such as displayed in Figure 1.
  • a syringe pump from KD Scientific, model KDS200 with a polypropylene syringe of 30 ml was applied as syringe pump.
  • This syringe pump was filled with purified SiCI 4 in the fluid phase and set to a syringe rate of 0.5 ml/minute.
  • SiCI 4 was used which was obtained from VWR, The Netherlands of a purity of > 99%.
  • the SiCI 4 will be formed at the anode and will be returned to the cathode after possible extraction and purification.
  • the SiCI 4 is transferred, by the syringe pump and Teflon tubes, to the inlet of an evaporation device, consisting of a container with a volume of 3 litres, made of boron silicate and provided with a cover with inlet and outlet.
  • the cover is closed airtight by means of an O-ring and is subsequently, with the exception of the bottom, fully insulated with glass fibre mats.
  • the container's bottom is placed on a hot plate with a constant temperature of 200 0 C.
  • a valve has been placed between the syringe pump and the evaporation device so that, if necessary, the syringe can be replaced without this affecting the pressure in the evaporation device.
  • the outlet of the evaporation device is connected to the electrolytic cell by an insulated tube of boron silicate.
  • the purpose of the evaporation device is to evaporate the SiCI 4 for introduction into the reactor to prevent flash evaporation in the reactor.
  • the electrolytic cell according to the present example is as displayed in Figure 2.
  • the diameter of the external quartz tube is 60 mm and this external quartz tube has a total length of 400 mm.
  • the electrolyte is added in such a way that it fills one third part of the reactor.
  • the electrolytic cell was placed vertically in an electrical oven, which can be heated to 1200 0 C, where the top of the electrolytic cell has been placed outside the oven.
  • the oven is an electrical oven obtained from Westeneng Ovenbouw, The Netherlands and had a simple control unit which makes it possible to set the temperature prior to the reaction.
  • the anode has been made of two strips of n-type silicon of electronic purity, doped with phosphorus, with a resistivity between 1 and 30 ohm. cm.
  • the purity of this material was greater than 99.9999%.
  • the strips are approximately 1 cm wide, 15 cm long and 1 mm thick. In each strip, there is a recess on one end which was applied for attaching the strips to the end of a tungsten rod (2 mm diameter) by application of platinum wire. The other end of the tungsten rod was connected to the potentiostat as counter electrode.
  • the silicon part of the anode was immersed in a 10% HF solution to remove any oxides from its surface. It will be clear that only the silicon part of the anode is in contact with the electrolyte.
  • the total anode area that was exposed to the electrolyte was at least 42 cm 2 .
  • the cathode has been made of tungsten (length 400 m, diameter 2 mm), immersed in the electrolyte. SiCI 4 , which serves as starting material, was supplied as a gas along the surface of this cathode.
  • the tungsten electrode had a total reaction area of approximately 11 cm 2 .
  • the other end of the rod was connected r
  • the pseudo reference electrode was a platinum wire with a diameter of 0.5 mm with an active reaction area of approximately 0.75 cm 2 .
  • the electrolyte was a eutectic mixture of 50 mole percent KCI (99.5% purity) and 50 mole percent NaCI (99.5% purity) with a melting point of 650 0 C.
  • the total salt mass that was applied in the electrolyte was 880 g.
  • the salt mixture was placed in a quartz reactor tube and heated to a temperature of 810 0 C to melt. After melting, the oven temperature was set to a temperature of 710 0 C and the electrolyte was kept at this temperature for the entire duration of the experiment. Before the electrodes were allowed to sink into the electrolyte, any dissolved oxides in the melt were removed by the addition of a small quantity of NH 4 CI (99% purity).
  • the KCI, NaCI and NH 4 CI were all obtained from VWR, The Netherlands.
  • the potentiostat with 3 electrodes was of the type PAR-273-A, manufactured by EG&G Princeton Applied Research, and was computer-controlled with the LabVIEW programme. This was applied to carry out cyclic voltammetric tests on the electrolytic cell. All experiments were carried out in an atmosphere of argon gas and any vapours that are released at the electrodes are condensed. Any not condensed gas was led through water to neutralize any SiCI 4 still present in it.
  • the electrode contains high levels of both tungsten, which is to be expected according to the present method, and silicon, which is deposited on the electrode. Furthermore, small quantities of impurities are present. From this analysis, it can be determined that a silicon layer is indeed deposited on the tungsten cathode.
  • the electrolyte parts with black deposit were dissolved in water and washed to obtain a black powder which was analysed.
  • the EDX analysis of the black powder is displayed in Figure 5. The analysis shows that the powder is largely pure silicon with very small quantities of sodium from the electrolyte. It is possible that this sodium was deposited during the electrolysis of the electrolyte to determine the background. It was assumed that the silicon powder had a porous structure with a particle diameter of approximately 50 ⁇ m.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Silicon Compounds (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
  • Formation Of Insulating Films (AREA)

Abstract

La présente invention concerne un procédé de purification d'un matériau semi-conducteur dont les étapes consistent à : a) oxyder au niveau d'une anode qui est placée dans un électrolyte anodique, un matériau semi-conducteur solide à purifier par application d'un composé ionique ou plus; b) réduire au niveau d'une cathode qui est placée dans un électrolyte cathodique, un ou plusieurs composés obtenus à l'étape a) pour obtenir un matériau semi-conducteur solide purifié, au moins un composé ionique étant également formé; le ou les composés ioniques formés à l'étape b) étant appliqués à l'étape a) et l'anode et la cathode étant connectées pour le transfert d'électrons. Les composés ioniques formés sont purifiés en externe. Le présent procédé peut par exemple être appliqué pour la purification de silicium.
EP07747296A 2006-05-03 2007-05-01 Procédé de purification d'un matériau semi-conducteur par application d'une réaction d'oxydo-réduction Withdrawn EP2013379A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL1031734A NL1031734C2 (nl) 2006-05-03 2006-05-03 Werkwijze voor het zuiveren van een halfgeleidermateriaal onder toepassing van een oxidatie-reductiereactie.
PCT/NL2007/000114 WO2007126309A2 (fr) 2006-05-03 2007-05-01 Procédé de purification d'un matériau semi-conducteur par application d'une réaction d'oxydo-réduction

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US (1) US20090127125A1 (fr)
EP (1) EP2013379A2 (fr)
JP (1) JP2009535515A (fr)
AU (1) AU2007244040A1 (fr)
CA (1) CA2650738A1 (fr)
NL (1) NL1031734C2 (fr)
WO (1) WO2007126309A2 (fr)

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WO2014004610A1 (fr) * 2012-06-27 2014-01-03 Arizona Board Of Regents, A Body Corporate Of The State Of Arizona, Acting For And On Behalf Of Arizona State University Système et procédé pour l'électroraffinage de silicium
WO2014201207A2 (fr) 2013-06-14 2014-12-18 Arizona Board Of Regents, A Body Corporate Of The State Of Arizona, Acting For And On Behalf Of Arizona State University Système et procédé de purification d'un sel électrolytique

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WO2007126309A3 (fr) 2008-04-03
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WO2007126309A2 (fr) 2007-11-08
US20090127125A1 (en) 2009-05-21
NL1031734C2 (nl) 2007-11-06
CA2650738A1 (fr) 2007-11-08

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