CN101555010A - Carborundum - Google Patents
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- CN101555010A CN101555010A CNA2008100914411A CN200810091441A CN101555010A CN 101555010 A CN101555010 A CN 101555010A CN A2008100914411 A CNA2008100914411 A CN A2008100914411A CN 200810091441 A CN200810091441 A CN 200810091441A CN 101555010 A CN101555010 A CN 101555010A
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Abstract
The invention relates to carborundum. The content of the impurity of a fifth element of the carborundum is within a specific range, and a carbothermic reduction method, a production method by a purification method and a purpose of being industrially used as a reducer of the carborundum are provided.
Description
Background of invention
The present invention relates to a kind of novel silicon carbide, and provided the production method and the purposes of this silicon carbide.
Present industrial silicon carbide mainly is divided into common silicon carbide and semiconductor grade silicon carbide (single-crystal silicon carbide body).
The common silicon carbide of industrial production, two class methods are generally arranged: the carbothermic method of silica or ground silica, silica/powder (being silicon-dioxide) and carbonaceous material are mixed into reaction material by suitable proportioning, place in the insulating container, utilize resistance or other modes to heat, make reaction material that redox reaction take place about 1400～2600 ℃ and generate silicon carbide, this method can be used to produce black silicon carbide and green silicon carbide; Silicon and carbon direct reaction method generate silicon carbide with elemental silicon (as Pure Silicon Metal) powder and the direct at a certain temperature combination reaction of carbon dust, and solid state reaction and gas-phase reaction are arranged usually, and difference is different reaction raw materials, hybrid mode and type of heating.
For example, Chinese patent application 02122377.7,89103262.2 is described the silicon carbide production method that can range above carbothermic method and carbothermy in detail.
The common silicon carbide that above method is produced, be particulate state, size is about 0.1～6mm, and particle is an erratic composition, or form loose or hard irregular agglomerate by particle, usually presenting black or green, is silicon carbide microcrystal mixture, and silicon carbide-containing is usually 90～95%, reach as high as 98.5～99%, except that containing unreacted carbon and silicon, being adsorbed with a large amount of gases, comprise outside nitrogen, the oxygen etc., also contain unreacted carbon, silicon (or silica) and a large amount of other element impurity.This is owing to contained impurity element in material carbon and silica or the silicon enters wherein.Main as high grade refractory, abrasive material and metallurgical raw material.
Producing thyrite generally needs the carborundum powder of higher degree.Because the common purity of silicon carbide that above method directly obtains is not enough, the purity that is used to produce ceramic material is obtained by the way that the silicon carbide super powder is removed impurity through matting usually greater than 96% silicon carbide, for example the method that is provided in the Chinese patent application 200610115158.9.
Powder diameter is thin more, and the purity that matting (pickling and alkali cleaning etc.) may reach is high more, and in theory, particle diameter is when micron order, and purity may reach about 99%, impurity element, and for example aluminium can be reduced to hundreds of ppm.But silicon carbide is superhard material, is difficult to obtain the following particle diameter of micron by mechanical workout; And when particle diameter reached micron or submicron, the method that adopts matting to purify because of adsorption increases, in fact was difficult to operation.
Semiconductor grade silicon carbide is the single-crystal silicon carbide body normally, has very high purity, adopts chemical vapor deposition method or method of evaporation production usually.For example, place vacuum oven or special atmosphere oven to heat sic raw material, silicon carbide evaporation back recrystallization is described as Chinese patent application 200510042914.5; Chinese patent application 97102232.1 has been described mixed gas by siliceous and carbon is provided under certain temperature and atmosphere, chemical reaction takes place, the carborundum crystals thin layer of emanating out in substrate.
Similarly method also is used for making structural (stratified) carbofrax material with particular electrical characteristic, for example PN junction.Manufacture the semi-conductor carbofrax material, its PN junction electrology characteristic comes from and is doped with N type doping agent in the high-purity carborundum monocrystalline, as nitrogen, the ten No. five element; With P type doping agent, as aluminium, No. five element.The concentration of doping agent, according to different electrology characteristic requirements, can be 10
15～10
19Cm-3, these doping agents are added in the silicon carbide monocrystal growth process usually equably, perhaps generate single-crystal silicon carbide after, adopt such as modes such as thermodiffusion, directly particle bombardment, neutron transmutation dopings evenly to add.Doping agent forms specific structural distribution in carborundum crystals, as layer distributed.
Because semiconductor grade silicon carbide is to be formed by the single-crystal silicon carbide bulk-growth, it has the macroshape of rule.As large-sized single crystal, or the single crystal film.
The semiconductor grade content of carborundum impurities requires extremely low, and carbon containing, silicon, oxygen and other element impurity generally all can not surpass 10
13～10
16Atom/cm
3, manufacture difficulty is big, and is with high costs.
Summary of the invention
The invention provides a kind of novel silicon carbide, though can have and the similar porous outward appearance of common silicon carbide, density, structure, but it is different from above-mentioned common silicon carbide, and its feature is that No. five element of impurity element and/or the ten No. five element equal size are in being limited in specific scope; Simultaneously, it also is different from semiconductor grade silicon carbide, it can contain a large amount of carbon (surpass 1～100ppm), silicon or silicon-dioxide composition, on microcosmic, present rambling small crystalline orientation, present small monocrystalline and polycrystalline random polymerization body structure.Because of its special impurity content and structure, this novel silicon carbide has the new purposes that is different from common silicon carbide and semiconductor grade silicon carbide.The invention provides special new purposes of this novel silicon carbide and production method.
Specifically, novel silicon carbide material of the present invention, it is characterised in that No. five element that contains 0.005～10ppm (wt) in the material, according to further preferred scheme, this novel silicon carbide contains the ten No. five element of 0.01～10ppm (wt) simultaneously; And according to the further preferred version of its purposes, it contains No. five element of 0.1～1ppm, the scheme of suboptimum, and the upper limit of No. five element reaches 2～5ppm; Or the like.
The newfound purposes of this silicon carbide, be can be as adopting silica to produce the reductive agent of silicon, silicon with this silicon carbide and silica production, its No. five constituent content can be controlled in certain scope, can be used as the raw material of semiconductor silicon material, particularly have the raw material of the semiconductor silicon material of light-electric transition effects.
Present industrial employing carbon at high temperature reduces the method for silica and produces silicon.Because the carbon raw material contains No. five higher element usually, the silicon that this method is produced, contain No. five higher element, it is the raw material that can not directly not be used as semiconductor silicon material, also can't directly remove No. five element in the silicon, need this silicon to be transformed into other silicon compounds (hydride compounds of silicon or chlorine compound) of lower boiling, retortable purification, be reduced into silicon through this silicon compound of having removed No. five element after will purifying again behind this silicon compound of purification with chemical process (as silane thermal decomposition process or Siemens Method).The silicon that adopts silicon carbide deacidizing silica of the present invention to obtain, because of its No. five element that contains limits within the specific limits, meet or the approaching requirement that meets the semiconductor silicon material raw material, only need directly to purify, remove other than higher impurity after, just can be used as the raw material of the raw material of semiconductor silicon material, particularly light-electricity conversion with semiconductor silicon material.
According to factors such as the purposes of final silicon materials and production costs, under the content of No. five element of feature impurity element of silicon carbide of the present invention and the prioritization scheme content of other impurity elements following listed (unit: ppm):
The further preferred P content of impurity B content is optimized single impurity metallic elements content again
Silicon carbide 0.005 of the present invention～10 0.001～10 0.1～200
Preferred version 1 class 0.005～0.01 0.001～0.01 0.1～1
Preferred version 2 class 0.01～0.1 0.01～0.1 1～10
Preferred version 3 class 0.1～1 0.1～1 10～100
Preferred version 4 class 1～2 1～5 10～50
Preferred version 5 class 2～10 5～10 50～100
Preferred version 7 class 0.1～0.8 0.1～1 10～50
Preferred version 8 class 0.01～0.1 0.01～0.1 1～10
Wherein, the silicon carbide of preferred version 1 class, high-purity silica that can be used for reducing is controlled at the silicon of 0.01ppm with interior (as 0.005ppm) to obtain No. five constituent content, and this silicon can be used as the raw material of production space flight level semiconductor silicon materials.The silicon carbide of preferred version 2 classes, the silica that can be used for reducing is controlled at 0.1ppm with interior silicon to obtain No. five constituent content, and this silicon can be used as the raw material of production general semiconductor silicon materials.The silicon carbide of preferred version 3 classes, the silica that can be used for reducing is controlled at 1ppm with interior silicon to obtain No. five constituent content, and this silicon can be as generally being used for producing the raw material of luminous energy-electric energy conversion with silicon materials.The silicon carbide of preferred version 4 classes, the silica that can be used for reducing is controlled at 2ppm with interior silicon to obtain No. five constituent content, also can be as the raw material of the lower silicon materials of the requirement of producing light-electricity conversion usefulness.The silicon carbide of preferred version 5 classes, the silica that can be used for reducing is controlled at 10ppm with interior silicon to obtain No. five constituent content, and this silicon can be used as the raw material of producing the lower silicon materials of the requirement of light-electricity conversion usefulness with special process.Preferred version 7 classes and 8 classes are suitable for industrial lower production cost production general semiconductor respectively and use the semiconductor silicon raw material with silicon raw material and the conversion of light-electricity.
1～8 class preferred version of silicon carbide among the present invention, for being suitable for the silicon raw material of low cost production semi-conductor, can distinguishing the scheme of the ten No. five constituent content restriction more preferably as listed above and/or optimize the scheme that single metal element content limits again with silicon materials.Wherein, for being easy to be purified to the needed metal element content of semiconductor material and to consider cost factor, have a kind of metallic element as impurity at least, for example aluminium is limited in the 100ppm, in the preferred 30ppm, is preferably in the 10ppm.These silicon carbide further preferred or prioritization scheme are particularly conducive to lower cost, less purification step, obtain to can be used to produce the silicon raw material of semi-conductor with silicon materials.
The example of described semi-conductor with silicon materials is described, includes, but is not limited to (monocrystalline) silicon rod, (polycrystalline) silicon ingot.These silicon materials can be cut into the silicon chip that semi-conductor is used.These silicon materials can be handled directly acquisition through crystal growth or ingot casting with No. five satisfactory silicon raw material of impurity content such as element.
Silicon carbide of the present invention is used for producing the silicon raw material of semi-conductor with silicon materials, can adopt following method: silicon carbide of the present invention and silica (silicon-dioxide) high temperature is warm altogether, silicon carbide will reduce silica, and silicon carbide self decomposes, and generates elementary silicon and carbon monoxide at last.Elementary silicon is separated from reaction mixture, just obtained to contain No. five the lower silicon of element.This silicon that contains No. five element is lower through directly purifying, is removed other impurity of part, just obtain to can be used to produce the silicon raw material (bulk or particulate state polycrystal) of semi-conductor with silicon materials.In the reaction of silicon carbide deacidizing silica, the molar ratio of raw material silicon carbide and silica is 2: 1.
The concrete production technique of a kind of usefulness silicon carbide deacidizing silica of the present invention is, in the hot stove in ore deposit, heat-flash silicon carbide smelting and silica mixture material with the generation of Graphite Electrodes electrical discharge arc, in the chamber, molten bath that the nearly bottom electrical arc of the hot stove in ore deposit forms, just can generate fused silicon liquid, draw this silicon liquid, cooling just obtains silico briquette.If with No. five element control silicon carbide and the HIGH-PURITY SILICON masonry reaction mixing raw material within the specific limits that contain of the present invention, it contains the silico briquette that obtains No. five element and just can control within the specific limits, purify through direct removal of impurities, the silicon material that obtains just can be as producing the silicon raw material of semi-conductor with silicon materials.
Another concrete production technique with silicon carbide deacidizing silica of the present invention is, silicon carbide fine particle and the mixing of high-purity silica fragment are placed high-temperature resistant container, as quartz or crystal vessel, be heated to 1400～2700 ℃, raw material reacts in container and just generates silicon, the silicon that generates is separated with remaining raw material, just obtain to contain No. five the low silicon of element.For reaction is carried out efficiently, it is useful that temperature is carried out suitable control.Temperature is more than 1830 ℃ the time, silicon generates fast, but be higher than 2100 ℃ particularly more than 2230 ℃ the time, because a large amount of volatilizations of reaction intermediate SiO, silica (SiO2) also evaporates volatilization (2230 ℃ of SiO2 boiling points), and the silicon carbide that does not reach reaction simultaneously densification also takes place changes (2100 ℃ of beginning transition temperatures), is the silicon carbide (alpha's silicon carbide) of high-density low reaction activity from the structural transformation of loose porous high reaction activity, form dead material, can reduce the yield of silicon.Therefore, preferred Heating temperature scope is at 1800～2100 ℃.On the other hand, at the fusing point 1670 of silica or below 1710 ℃, material silex and silicon carbide are solid-state, if and the silicon that generates is more than 1400 ℃, to break away from reaction raw materials with liquid state, reaction is carried out smoothly and product silicon is separated from raw material, therefore, preferably another Heating temperature scope is 1400～1670/1710 ℃ (1670 ℃ and 1710 ℃ is respectively the fusing point of the silica of two kinds of crystal formations).
Because intermediate reaction product SiO volatilizees easily, reaction also generates gas CO, and reaction mass is preferably formed as certain piling height, and the subregion or the gradient-heated that preferably begin to heat from the bottom material or heat at lower region separately.Like this, heat and evaporable SiO are absorbed by the top material, generate small part silicon, and preheating top material, are unlikely to lose in a large number silicon and heat energy; Simultaneously, molten silicon mainly forms in the high-temperature zone, bottom, because of its density is big, directly be deposited on the bottom, reduced the adhesion of molten silicon and raw material or mixed, the another kind of product C O of reaction is volatilization upwards, the molten silicon of bottom deposit is derived, and cavity is just formed at the material bottom, and the top material is fallen the lower heating district and is heated to temperature of reaction, continue to generate silicon, raw material can be continued to add in the space that top subsides.Like this, reaction just continues to go in an orderly manner.The distribution mode that is suitable for this raw material and product is preferably used vertical or vertical vessel holds reaction raw materials, for example, and vertical tubulose or bulk containers.
For mode, for improving the collection effciency and the production efficiency of silicon, best usage level or tilted-putted elongated tubular container with the whole heating of the reaction raw materials in the container.Heating to raw material in the tubular vessel is more convenient, same heating perimeter line, and the raw material volume that comprises is bigger; The silicon that reaction generates is easy to concentrate the curved lower portion that flows to tube wall, and than the mode that is easier to by the inclination tube wall, from long tube one end centralized collection silicon.In addition, the elongated tubular container is easy to material subregion or heating are district by district helped the efficient utilization of heat energy and the orderly reaction of raw material.For example, for the raw material in the long tube that tilts, heating can begin progressively to prolong to high-end from low side, and the raw material reaction district progressively pushes to high-end from low side, and the material of reaction and heat energy are all efficiently utilized.
The technology of heating can adopt the resistance-type heating of the internal or external resistor core of mixing raw material, also can take the mode of direct or indirect induction heating.Different type of heating preferably is equipped with the structure of container that adapts.As adopt the material center to put the mode of conductive core heating, preferably be equipped with major diameter type container, as the elongated tubular container; Adopt direct induction heating, utilize the silicon carbide inductive loop heating of conducting electricity in the raw material, then can adopt crucible to describe device or tubular vessel.Indirectly induction heating is with the high performance induction heating unit at material or external container cover, as graphite cannula or carbon tube, can perhaps, in the crystal vessel that can respond to heating, directly hold reaction raw materials by conducting heat to the material of receptacle behind heating graphite cannula/pipe.
The reaction of silicon carbide deacidizing silica can generate a large amount of CO gases.For promoting normally carrying out of reaction, the gas of generation will in time be derived conversion zone.In open reaction environment, the environment as reacting in the thermic arc stove of conventional ore deposit needs the material good permeability, and silica is the fragment of the most handy 3～100mm, preferred 5～50mm, further preferred 10～30mm.If in airtight Reaktionsofen, should keep metastable pressure in the stove, preferably be negative pressure, to promote the discharge of CO.Reaction vessel can be connect with vacuum pump, and connect source nitrogen, control the pressure in the container continuously, when the predetermined negative pressure of pressure is high, vacuum pump quickening work, when pressure was lower than predetermined pressure, nitrogen was filled in source nitrogen work in container.The CO that also can collect the reaction generation replaces nitrogen, regulates the pressure in the container.
In airtight Reaktionsofen, the CO that reaction produces can be collected recycling.
For preventing to occur blast or detonation (airborne oxygen and CO vigorous reaction) in the encloses container, the silica reduction reaction of carrying out at encloses container, need use inert atmosphere during beginning, as with the oxygen in nitrogen or the argon gas amount discharge container, in the reaction process of carrying out, prevent that air or oxygen from bleeding in the encloses container.
The silica reduction reaction of the generation silicon that carries out at encloses container, the reaction vessel that holds material can use the high-melting point metal crucible, as tungsten, molybdenum or miramint crucible.Even a small amount of diffuse pollution is arranged, heavy metals such as tungsten or molybdenum are also separated from silicon easily.But because of cost is low, high temperature resistant, accomplish high purity easily, plumbago crucible remains preferably as reaction vessel, and other container material comprises quartz, aluminum oxide (corundum), zirconium white etc.
Adopt silicon carbide deacidizing silica of the present invention to produce the silicon raw material of semi-conductor, can also add an amount of additional reductive agent, in order to improve the foreign matter content of reaction environment, reduction silicon with silicon materials.Additional reductive agent can also can use other carbonaceous high-purity reductive agents with carbon or carbide.Wherein, carbide comprises various metallic carbide, as carbide of calcium, lithium carbide, sodium carbide, kalium carbide etc.The present invention finds, uses carbide reductive agent as a supplement, also has the effect of removing No. five element impurity in the part material in reduction process.Because of can at high temperature forming with silica, the metallic element in the carbide contains-SiO
2Slag, when these fused slags contact with molten silicon, the effect of extracting No. five element in the molten silicon is arranged, and No. five element is separated from silicon.A typical example of making the carbide of additional reductive agent is a carbide of calcium.
Replenish the amount of reductive agent, can specifically adjust according to the situation of raw material and additional reductive agent self foreign matter content, usually, additional reductive agent can account for 10～30% of total reductive agent, in particular cases, can surpass 50%.
The carbon of purifying can be used as the additional reductive agent of silicon carbide deacidizing silica production semi-conductor usefulness silicon raw material among the present invention, it can improve the working of a furnace to a certain extent, reduce cost, but still contain more impurity owing to have the carbon of the purifying of reducing activity, particularly No. five element and the ten No. five element, the ten No. five higher constituent content makes the silicon that generates need the long vacuum purification processes time.When therefore using carbon to do to replenish reductive agent, its consumption will carefully be controlled, so that the direct purification step of back can produce a desired effect with suitable cost.
Silicon carbide of the present invention can adopt common silicon carbide to remove No. five element impurity of part through purifying and obtain, and also available No. five constituent content is controlled at carbon raw material reduction in the specified range and contains silica material and directly produce.Wherein, " carbothermic method of silica ", the method that is about to carbon and silica mixture material heating acquisition silicon carbide is simple.Generate the chemical equation of silicon carbide according to the carbon reduction silica, to contain the silica that No. five element is lower than 0.1ppm, be heated to 1100～2700 ℃ with containing the mixture that No. five element be lower than the carbon of 0.1ppm, just generate the silicon carbide that No. five element is lower than 0.24ppm that contains of the present invention.Mixture can be embedded in the insulation material of quartz sand composition usually, and with graphite resistance core energising heating, in the mixture, the mol ratio of silica (silicon-dioxide) and carbon is 1: 3.If silica contains No. five element and is lower than 0.1ppm in the raw material, and carbon contains No. five element and is lower than 0.01, and reaction generates and contains the silicon carbide that No. five element is lower than 0.16ppm; Silica contains No. five element and is lower than 0.01ppm in raw material, and carbon contains No. five element and is lower than 0.01, and reaction generates and contains the silicon carbide that No. five element is lower than 0.024ppm; The highest No. five constituent content of the silicon carbide that i.e. reaction generates depends on No. five constituent content in the raw material.Available following formula calculates the highest No. five constituent content: B (SiC)=[60*B (SiO2)+36*B (C)]/40 of silicon carbide, and wherein, B (SiC), B (SiO2), B (C) represent No. five constituent content in silicon carbide, silica, the carbon respectively.
Because No. five element of impurities in raw materials volatilization can occur at high temperature in the reaction, it is lower that the comparable following formula of No. five constituent content of the actual silicon carbide that obtains calculates.In the real example provided by the invention, adopt carbothermic method, used the raw material of different No. five constituent contents, obtained to contain No. five element silicon carbide respectively at 10ppm, 2ppm, 1ppm, 0.6ppm, 0.2ppm, 0.1ppm, 0.05ppm, 0.01ppm, 0.005ppm.
Adopt carbothermic method to produce silicon carbide of the present invention, need No. five constituent content in each raw material lower, and auxiliary material also controls within the specific limits as the graphite of heating usefulness or No. five constituent content in the Graphite Powder 99 combustion chamber, have relatively high expectations.
For this reason, the present invention finds, when carbothermic method is produced silicon carbide, add a small amount of halogen, as sodium-chlor, Calcium Fluoride (Fluorspan), or feeding chlorine or hydrogen chloride gas, can reduce No. five constituent content of silicon carbide products, use the raw material contain No. five element is high to produce and contain the low silicon carbide of element No. five.A real example is to get the carbon fine particle that contains No. five element 1ppm material silex fine particle and contain No. five element 1ppm, the sodium chloride powder of adding 10%, mixing places in the silicon carbide furnace, does insulation material with glass sand and quartz wedge, make energising heating resistor core with the high purity graphite powder, energising heating 24 hours makes that reaction material is the highest to be warmed up to more than 2000 ℃ the silicon carbide of generation, after testing, contain element 0.3ppm No. five.
In addition, the invention provides the production method of another kind of silicon carbide of the present invention, be referred to as the heat alkali liquid method of purification.Common silicon carbide or carbothermy production of the present invention contained No. five amount of element silicon carbide fine particle or powder at 0.1～10ppm; be soaked in certain hour in hot alkali aqueous solution or the alkaline aqueous solution; centrifugal then elimination alkaline solution; and clean repeatedly with deionized water; be heated to 50～120 ℃ of oven dry at last; the silicon carbide that obtains, it contains No. five amount of element can reach 0.005～1ppm.Analyze to find that No. five element in the raw material silicon carbide moved to the surface of silicon-carbide particle body by the thermodiffusion effect, extracted stripping by the water and steam of alkaline solution and heat and take away.Silicon-carbide particle is thin more, and the stripping of No. five element is many more.Be generally No. five element that can make in the silicon carbide and be reduced to suitable content, silicon-carbide particle should preferably less than 100 microns, but should not be lower than 0.1 micron less than 1 millimeter.In present method, alkaline solution can be used alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide, perhaps alkali-metal carbonate, and as yellow soda ash, or ammoniacal liquor or ammonium salt solution, as NH
4HCO
3, or the mixing solutions of above-mentioned a kind of or several alkali or basic salt.The volumetric molar concentration of alkaline solution should be higher than the total mol concentration of the impurity content of No. five constituent content of impurity in the silicon carbide and other and alkali reaction, preferred 1～5 times to the volumetric molar concentration of impurity.The heat alkali liquid temperature is high more, and the time is long more, and No. five element impurity of stripping is many more.Heat alkali liquid method of purification of the present invention is better to No. five element effect of removing in the silicon carbide especially, and the normal temperature pickling alkali cleaning impurity removal method of general silicon carbide, and step is simpler, and loss is lower.
The invention provides the production method of another silicon carbide of the present invention, be referred to as the molten method of purification of salt: get halide salts such as Calcium Fluoride (Fluorspan), Sodium Fluoride, sodium-chlor, Na3AIF6, or silica, yellow soda ash, water glass, Calucium Silicate powder, rhombspar (CaMg[CO3] 2), and CaO-MgO-SiO
2, CaO-BaO-SiO
2, CaO-CaF
2-SiO
2, CaO-SiO
2-CaCl
2, Na
2O-SiO
2Deng a kind of in the fused salt of 1000～2000 ℃ or lower temperature of fusing point or several are an amount of; as purification flux; silicon carbide fine particle or powder are mixed with the fused salt of being got; be heated to the salt fusion; fully stir and make silicon carbide and fused salt mixing and keep certain hour; some impurity that comprise No. five element in the silicon carbide; just move in the fused salt; silicon carbide is separated from fused salt; require and initial No. five constituent content according to No. five constituent content of setting; repeat this process one or many, just obtain the low silicon carbide that contains No. five element of the present invention.Silicon carbide is separated from fused salt, can be utilized the differential liberation of both density, as with settling process or centrifuging.For the salt of water soluble or other solvents, can cool off back water or dissolution with solvents, flush away salt.It should be noted that when using oxidiferous fused salt that high-temperature lower part divides the silicon carbide can oxidational losses, therefore, should use the lower fused salt of fusing point as far as possible, or the fused salt of oxide-free.
Discover that silicon carbide of the present invention, its impurity element comprise carbon (1～1000ppm even higher), mainly be when generating silicon carbide reactor in the raw material unreacted carbon sneak into wherein, these carbon can't influence the performance of silicon carbide of the present invention as reductive agent.No. five element of the characteristic element of silicon carbide of the present invention, be not as in the semi-conductor carborundum crystals, be uniformly distributed in the small crystalline lattice of silicon carbide, but be distributed in the interface of silicon carbide tiny crystal grains more and be entrained in the pore gap, and exist with the form of oxide compound more; With main group element aluminium impurity too.Other impurity elements, as the ten No. five element, also be different from the semi-conductor carborundum crystals to mix up the ten No. five element the same, but distribution heterogeneous relatively; How impurity such as iron, calcium, magnesium are deposited on the interface of crystal grain and in the pore with alloy or carbide, oxide compound state.Simultaneously, silica in the raw material or silicon also have to be mixed on a small quantity in the silicon carbide, independently have or adhere to and be mingled with existence.The impurity of Fen Buing is different from semiconductor grade single-crystal silicon carbide body like this, and is removed easily.
Therefore, silicon carbide of the present invention also is more prone to remove impurity than material silex.Simultaneously, carbothermic method and the aforesaid back methods of purification such as molten method of purification of salt and heat alkali liquid method of purification that comprise are combined, can from the raw material that No. five constituent content is higher, obtain low No. five element silicon carbide of the present invention.
Embodiment
Produce silicon carbide of the present invention
Embodiment 1
Get the silicon carbide that contains No. five element 12ppm, particle diameter＜/=5 micron, place the sodium hydroxide solution of 0.1 mole/L, be heated to 50 ℃, be incubated 96 hours, centrifugal filtering sodium hydroxide solution, clean repeatedly 5～20 times with deionized water, oven dry, the silicon carbide of acquisition contains element 0.9ppm after measured No. five.
Embodiment 2
Get the silicon carbide that contains No. five element 5ppm, particle diameter 300 orders place the potassium hydroxide solution of 0.1 mole/L, at encloses container internal heating to 120 ℃, be incubated 48 hours, cooling is taken out, and centrifugal filtering potassium hydroxide solution cleans 5～20 times repeatedly with deionized water, the deionized water that adds 1 times of amount at last, boil and boil moisture content dry, the silicon carbide of acquisition contains element 0.8ppm after measured No. five.
Embodiment 3
Get the silicon carbide powder (200 order) that contains No. five element 5ppm, with Calcium Fluoride (Fluorspan), the Sodium Fluoride mixing of 10 times of amounts and be heated to fused solution, fully stirring is scattered in the fused salt infusible silicon carbide powder, and kept cooling, fragmentation 18 hours, add the ammonium salt solution dissolving and remove Calcium Fluoride (Fluorspan), Sodium Fluoride, and clean oven dry, and obtain silicon carbide, recording its No. five constituent content is 0.3ppm.
Embodiment 4
The silica in small, broken bits that will contain No. five element 0.08ppm, mix with 1: 3 in molar ratio of the carbon granule that contains No. five element 0.08ppm, place the high purity graphite powder to do in the holding furnace of heat generating core, mixing raw material embedding heat generating core, the mixing raw material outside covers glass sand and quartz wedge insulation, the energising heating, stop heating after 36 hours, insulation material is pushed in cooling aside, just obtain silicon carbide of the present invention around the heating graphite core, it contains element 0.19ppm No. five.Use quartz wedge can increase ventilation property, promote reaction to carry out smoothly.
Embodiment 5
The silica in small, broken bits that will contain No. five element 1ppm, mix with 1: 3 in molar ratio of the carbon granule that contains No. five element 1ppm, and add 5% sodium-chlor mixing, place the high purity graphite powder to do in the holding furnace of heat generating core, make mixing raw material embedding heat generating core, the mixing raw material outside covers glass sand and quartz wedge insulation, the energising heating, stop heating after 36 hours, insulation material is pushed in cooling aside, obtains silicon carbide of the present invention around the heating graphite core, the loose fine particulate that is caking, it contains element 1.8ppm No. five.If the sodium-chlor of adding 5% in the reaction blended stock, the silicon carbide of acquisition contains element 1.2ppm No. five.This silicon carbide is placed the sodium hydroxide solution of 0.1mol/L, place in the pressurized, heated still, be heated to 120 ℃, stirring also is incubated 48 hours, the filtering sodium hydroxide solution, extremely neutral with washed with de-ionized water repeatedly, filter is done, add deionized water submergence silicon carbide, be heated to and boil, and keep the water boiling, evaporate fully up to moisture content, the silicon carbide that obtains is measured its No. five constituent content 0.4ppm.
Silicon carbide of the present invention is used to produce the raw material of semi-conductor with silicon materials
Embodiment 6
Get the silicon carbide that No. five element, the ten No. five element are respectively 0.1ppm, aluminium 10ppm that contains of the present invention, mix with the high-purity silica that contains No. five element, the ten No. five each 0.1ppm of element, submerged arc heating in the thermic arc stove of ore deposit, obtain silicon, it contains element 0.2ppm No. five, contains the ten No. five element 0.1ppm (the ten No. five element of part be volatilization at high temperature in reduction process).This silicon can directly be purified as semi-conductor silicon raw material: with the silicon refuse in quartz or crystal vessel that obtains, logical oxygen removes carbon elimination and part aluminium, basic metal, alkaline-earth metal etc., logical argon gas removes deoxidation and other impurity of part (comprise aluminium, calcium), in container, make its slow condensation that makes progress from the bottom, in the excision, the part that following two ends slag inclusion and impurity are higher, the silicon that obtains is packed in the high-purity silica pot, in vacuum oven, melt, under diffusion pump vacuumizes condition, in 1550 ℃ of insulations 10 hours, make volatile impunty in the silicon, comprise the ten No. five element volatilization of basic metal and alkali earth metal and part, make slowly upwards condensation of silicon then from the quartz crucible bottom, excision 25% higher part of two ends foreign matter content up and down (is looked the concentration height of impurity, actually can respectively excise 10～35% or more up and down), the silicon that obtains, after measured, contain element 0.16ppm No. five, the ten No. five element 0.02ppm, total metal is less than 1ppm, single metal element content is less than 0.05ppm, can for example, be used as the silicon raw material of light-electricity conversion directly as producing the silicon raw material of semi-conductor with silicon materials with silicon crystal.
Embodiment 7
Get the silicon carbide that No. five element, the ten No. five element are respectively 0.05ppm, aluminium 10ppm that contains of the present invention, mix with the high-purity silica that contains No. five element, the ten No. five each 0.05ppm of element, place vertical high purity graphite pipe, carbon tube has flow-guiding mouth near the sidewall of bottom, and bootable liquid flows in the storage quartz silica crucible that places the next door.The bottom of vertical high purity graphite pipe is placed in the induction heater, and induction heater, vertical high purity graphite pipe, storage quartz silica crucible put into a sealed furnace that connects source nitrogen, after vacuumizing in the stove, fill, and keep furnace atmosphere pressure 0.8 atmospheric negative pressure state with nitrogen.With the bottom that induction heater heats vertical high purity graphite pipe, make the temperature of bottom reaction material in the pipe reach 1500～2200 ℃, the result, molten silicon flows out from flow-guiding mouth and enters the storage silica crucible.After testing, contain element 0.08ppm in this silicon No. five, contain element 0.07ppm the ten No. five.This silicon can be used for being purified to the silicon raw material that semi-conductor is used.
Mix high pure carbon with silicon carbide of the present invention and produce semi-conductor silicon raw material
Embodiment 8
Get 7 parts in the silicon carbide that No. five element, the ten No. five element are respectively 0.1ppm, aluminium 10ppm that contains of the present invention, the purified carbon particle that mixing is low with the degree of graphitization of 3 parts (mole numbers), reducing activity is high (contains element 3ppm No. five, the ten No. five element 6ppm), mix with the high-purity silica that contains No. five element, the ten No. five each 0.1ppm of element, in the thermic arc stove of ore deposit, heat, obtain silicon, it contains element 0.5ppm No. five, contains the ten No. five element 0.7ppm (the ten No. five element of part be volatilization at high temperature in reduction process).This silicon can directly be purified as semi-conductor silicon raw material: with the silicon refuse in quartz or crystal vessel that obtains, logical oxygen removes carbon elimination and part aluminium, basic metal, alkaline-earth metal etc., logical argon gas removes deoxidation and other impurity of part (comprise aluminium, calcium), in container, make its slow condensation that makes progress from the bottom, in the excision, the part that following two ends slag inclusion and impurity are higher, the silicon that obtains is packed in the high-purity silica pot, in vacuum oven, melt, under diffusion pump vacuumizes condition, in 1550 ℃ of insulations 24 hours, make volatile impunty in the silicon, comprise the ten No. five element volatilization of basic metal and alkali earth metal and part, make slowly upwards condensation of silicon then from the quartz crucible bottom, the higher part of the foreign matter content of two ends up and down of back silicon ingot is solidified in excision, the silicon that obtains, after measured, contain element 0.4ppm No. five, the ten No. five element 0.03ppm, total metal is less than 1ppm, single metal element content is less than 0.1ppm, can be directly as producing the silicon raw material of semi-conductor with silicon materials, for example, as the silicon raw material of light-electricity conversion with silicon crystal.
Embodiment 9 usefulness silicon carbide of the present invention mixes the quartzy semi-conductor silicon raw material of producing of high-purity carbide of calcium reduction
Get 70 parts in the silicon carbide that No. five element, the ten No. five element are respectively 0.5ppm, aluminium 10ppm that contains of the present invention, mixing (contains element 0.5ppm No. five with the carbide of calcium particle of 30 parts (mole numbers), the ten No. five element 0.5ppm, aluminium 10ppm), mix with the high purity quartz that contains No. five element, the ten No. five each 0.5ppm of element, aluminium 10ppm, in the thermic arc stove of ore deposit, heat, obtain silicon, it contains element 0.4ppm No. five, contain the ten No. five element 0.8ppm (the ten No. five element of part be volatilization at high temperature in reduction process, and part is scattered in the fused salt).This silicon can directly be purified as semi-conductor silicon raw material: with the silicon refuse in quartz or crystal vessel that obtains, logical oxygen removes carbon elimination and part aluminium, basic metal, alkaline-earth metal etc., logical argon gas removes deoxidation and other impurity of part (comprise aluminium, calcium), in container, make its slow condensation that makes progress from the bottom, in the excision, the part that following two ends slag inclusion and impurity are higher, in the high-purity silica pot that the silicon that obtains is packed into, in vacuum oven, melt, under diffusion pump vacuumizes condition, in 1500 ℃ of insulations 40 hours, make volatile impunty in the silicon, comprise the ten No. five element volatilization of basic metal and alkali earth metal and part, make slowly upwards condensation of silicon then from the quartz crucible bottom, the back higher part of two ends foreign matter content is up and down solidified in excision, the silicon that obtains, after measured, contain element 0.4ppm No. five, the ten No. five element 0.04ppm, total metal is less than 1ppm, single metal element content is less than 0.1ppm, can be directly as producing the silicon raw material of semi-conductor with silicon materials, for example, as the silicon raw material of light-electricity conversion with silicon crystal.
Here, form total No. five constituent content of higher raw material of silicon, extract, No. five constituent content in the product silicon reduced relatively through the enrichment of fused salt slag.In addition, originally discover, using silicon carbide and additional reductive agent reduction silica when obtaining the silicon of low No. five element, in the reaction mixture as add an amount of halogen salt,, can strengthen and remove No. five element effect as calcium chloride or sodium-chlor.
Claims (15)
1, a kind of silicon carbide is characterized in that, this silicon carbide contains No. five element impurity at 0.005～10ppm, and is rendered as small monocrystalline and polycrystalline random polymerization body structure.
According to the silicon carbide of claim 1, it is characterized in that 2, described silicon carbide contains the ten No. five element impurity at 0.001～10ppm.
According to the silicon carbide of claim 2, it is characterized in that 3, at least a single metallic impurity elements is in 100ppm in the described silicon carbide.
According to the silicon carbide of claim 3, it is characterized in that 4, the impure aluminium element of described silicon carbide is in 30ppm.
5, produce as the method for the silicon carbide of claim 1～4, it is characterized in that, this silicon carbide at high temperature reduces and contains the silica acquisition at 0.002～10ppm of No. five element by containing No. five constituent content carbon at 0.002～10ppm.
6, the production method of silicon carbide according to claim 5 is characterized in that, adds halogenide in the raw material further to remove the impurity that comprises No. five element.
7, production is characterized in that, with alkaline solution or the basic solution lixiviate of silicon carbide fine particle via heat, to remove No. five unnecessary element impurity as the method for the described silicon carbide of claim 1～4.
8, production is characterized in that as the method for the described silicon carbide of claim 1～4, and silicon carbide is scattered in the fused salt, makes its No. five unnecessary migration of element that contains in fused salt.
9, the purposes of the described silicon carbide of claim 1～4 is characterized in that, this silicon carbide is made reductive agent, at high temperature reduces high-purity silica, to obtain No. five constituent content silicon at 0.005～10ppm.
10, the purposes of silicon carbide according to claim 9 is characterized in that, this silicon carbide is used to produce and contains the ten No. five element and be lower than the silicon that 10ppm, at least a single metallic element foreign matter content are lower than 100ppm.
11, the purposes of silicon carbide according to claim 10 is characterized in that, uses the material of other carbon elements do to replenish reductive agent, to obtain to contain No. five element silicon at 0.005～10ppm.
12, the purposes of silicon carbide according to claim 11 is characterized in that, the material of described other carbon elements is taken from a kind of in the material of next group or several: carbon, metallic carbide.
13, purposes according to the described silicon carbide of claim 10～12, it is characterized in that, the silicon carbide deacidizing silica is obtained silicon, a kind of or several process in again this silicon process being handled with next group, every kind of processing does one to for several times: the refining of ventilating under molten state, the silicon of molten state is incubated 1450～1600 ℃ of processing in a vacuum, the high part of back removal two ends foreign matter content is slowly solidified from the bottom to top or opposite direction in the silicon edge of molten state, silicon is done from one end to the other side the field method melting of passing gradually, so that obtain can be as producing semiconductor silicon material, contain element 0.005～10ppm No. five, contain element 0.001～10ppm the ten No. five, total metal is lower than the silicon raw material of 1ppm.
14, the purposes of silicon carbide according to claim 13 is characterized in that, silicon carbide and silica mixing raw material are placed vertical container, and the raw material of heating container inside makes its reaction obtain silicon.
15, the purposes of silicon carbide according to claim 13 is characterized in that, places elongated tubular container internal heating to obtain silicon in silicon carbide and silica mixing raw material.
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| CN102874810A (en) * | 2012-10-26 | 2013-01-16 | 浙江理工大学 | Preparation method of beta-SiC nano powder |
| CN104807743A (en) * | 2015-04-21 | 2015-07-29 | 北京航空航天大学 | Heating method for ceramic-based composite material |
| CN108178158A (en) * | 2017-11-28 | 2018-06-19 | 贾玉东 | The straight trough type resistance furnace collected exhaust gas and can be explosion-proof |
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| CN109721056A (en) * | 2019-02-28 | 2019-05-07 | 扬州中天利新材料股份有限公司 | The method that depth removes impurity element in high-purity silicon carbide powder |
| CN116395702A (en) * | 2023-03-24 | 2023-07-07 | 四川纳毕硅基材料科技有限公司 | Device and method for preparing high-purity silicon tetrachloride and polysilicon in short process |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102874810A (en) * | 2012-10-26 | 2013-01-16 | 浙江理工大学 | Preparation method of beta-SiC nano powder |
| CN104807743A (en) * | 2015-04-21 | 2015-07-29 | 北京航空航天大学 | Heating method for ceramic-based composite material |
| CN108178158A (en) * | 2017-11-28 | 2018-06-19 | 贾玉东 | The straight trough type resistance furnace collected exhaust gas and can be explosion-proof |
| CN108178158B (en) * | 2017-11-28 | 2022-11-01 | 贾玉东 | Straight-groove type resistance furnace capable of collecting waste gas and preventing explosion |
| CN108640117A (en) * | 2018-05-10 | 2018-10-12 | 南昌航空大学 | One kind synthesizing two dimension SiC ultrathin nanometer structures and preparation method thereof by template molten-salt growth method of graphene |
| CN108640117B (en) * | 2018-05-10 | 2022-03-25 | 南昌航空大学 | Two-dimensional SiC ultrathin nanostructure synthesized by molten salt method with graphene as template and preparation method thereof |
| CN109721056A (en) * | 2019-02-28 | 2019-05-07 | 扬州中天利新材料股份有限公司 | The method that depth removes impurity element in high-purity silicon carbide powder |
| CN116395702A (en) * | 2023-03-24 | 2023-07-07 | 四川纳毕硅基材料科技有限公司 | Device and method for preparing high-purity silicon tetrachloride and polysilicon in short process |
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