CN108328618A - A kind of method of hard inclusions in electromagnetic induction directional solidification divided silicon - Google Patents
A kind of method of hard inclusions in electromagnetic induction directional solidification divided silicon Download PDFInfo
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- CN108328618A CN108328618A CN201810089314.1A CN201810089314A CN108328618A CN 108328618 A CN108328618 A CN 108328618A CN 201810089314 A CN201810089314 A CN 201810089314A CN 108328618 A CN108328618 A CN 108328618A
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- directional solidification
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/02—Silicon
- C01B33/037—Purification
Abstract
The invention belongs to polycrystalline silicon smelting technical field, more particularly to the method for hard inclusions in a kind of electromagnetic induction directional solidification divided silicon.The present invention selects the top skin of polycrystalline silicon ingot casting/purification process generation, edge skin material as raw material, migration and the enrichment environment of hard inclusions are built using electromagnetic induction coupling directional solidification technology, hard inclusions are made finally to be enriched in ingot casting surface, and then it is removed, high purity silicon ingot is obtained, the significant effect of hard inclusions is removed using this method.
Description
Technical field
The invention belongs to polycrystalline silicon smelting technical field, more particularly to hard in a kind of electromagnetic induction directional solidification divided silicon
The method being mingled with.
Background technology
Solar-grade polysilicon is the main raw material(s) of photovoltaic industry, with the sustainable development of photovoltaic industry, to polysilicon
The demand of material is growing.China has become the maximum output state of polysilicon and demand state, and largely relies on import, and it is still necessary to expand
Big production scale.However, being reallocated by the impurity in preparation process and melting environment pollutes, the yield of polycrystalline silicon ingot casting
Less than 70%, ingot top region is rich in nitrogen impurity rich in carbon impurity, edge, can not directly utilize.The part silicon material is carried out
Purification, regains the polycrystalline silicon material of high-purity, realizes that the regeneration of silicon materials, economy and social effect are great.
After metallurgy method prepares the ingot casting process of solar-grade polysilicon, the yield of ingot casting is only 70%, top and
The ingot casting region of side nearly 30% has accumulated a large amount of SiC, Si3N4It is mingled with and metal impurities, the purity in these regions is only 3N
(99.9%).By preceding described, metal impurities have extremely effective purification mode at present.But for C, N and its generation is precipitated
SiC, Si3N4Nonmetal inclusion particle, due to the diversity in its source in various techniques, but also studying its distribution and going
Except there are certain difficulty, though achieving certain effect to the control of carbon, nitrogen impurity in traditional handicraft now, still cannot
Meet requirement of the higher quality solar cell to silicon materials, the also extremely difficult recycling of discarded tailing.
Existing method and shortcoming：
1, it filters
Filtering technique is mainly using ceramic sponge strainer, the SiC and Si in divided silicon tailing at high temperature3N4It is mingled with
Particle.When flowing through filter device containing the silicon liquid being mingled with, Si3N4The main surface for being enriched in filter screen, and SiC is mainly being filtered
It is attached to ceramic material surfaces in hole in net, while having filled up hole, further hinders particle and passes through strainer.Filtering
Process is the process of a gradation in batches, cannot achieve continuous production, and the particle only for grain size more than 10 μm has preferably
Separating effect, it is low for the smaller Particulate Inclusion separative efficiency of grain size, and a large amount of silicon liquids are adhered in inner wall in the process,
Cause the loss of silicon material.
2, it settles
That sedimentation techniques mainly utilize is SiC and Si in silicon3N4Inclusion density this physical property difference bigger than silicon melt.
Polysilicon tailing to then be carried out under high-temperature fusant, the solid particle in silicon melt can be settled gradually under gravity
To melt bottom, deposits and detached with silicon melt.But simple sedimentation separation is since melt is almost without mobility, sedimentation
Gravity is fully relied on, therefore disengaging time is long, separative efficiency is low.
3, directional solidification
Since the directional solidification technique that polycrystalline silicon ingot or purifying furnace uses is molten with segregating to less than 1 impurity for segregation coefficient
Effect at the top of body.Since C the and N segregation coefficients in silicon are respectively less than 1.Make impurity segregation to molten by way of directional solidification
To have the function that C and N in divided silicon at the top of body.But due to the extremely weak mobility of melt in directional solidification furnace, although trip
From C and N can with solid liquid interface promote and segregate to final solidified region, but its supersaturation be precipitated particle phase SiC and
Si3N4The ingot casting being distributed widely in after solidification, cannot achieve the separation of particle and silicon.
Invention content
To solve the above problem of the existing technology, the present invention provides in a kind of electromagnetic induction directional solidification divided silicon
The method of hard inclusions.In silicon refining process, outfield is applied by electromagnetic induction, silicon melt and hard inclusions are in Lorentz force
And its under the orientation stirring action of melt, hard inclusions are migrated in electromagnetic induction field and are enriched at the top of melt and side,
Hard inclusions are further enriched to by ingot top by directional solidification again, to be removed.Product hard made from this method
It is good to be mingled with removal effect, purification efficiency is high.
To achieve the above object, the technical solution adopted by the present invention is as follows：In a kind of electromagnetic induction directional solidification divided silicon
The method of hard inclusions, it is characterized in that：Include the following steps：
A. it feeds：It is packed into silica crucible and contains SiC and Si3N4The polycrystalline silicon ingot casting or purification process of hard inclusions produce
Raw top cladding, the content of silicon is 90-99wt% in raw material；
B. the temperature rise period：After charging, equipment vacuumizes, and is started to warm up after vacuum degree reaches 15Pa, the starting stage
It is power heating, the frequency of induction coil is 3000Hz, and changed power is 10kW (10min) -30kW (60min) -60kW
(16min)‐100kW；When temperature-control heat couple temperature is 1120 DEG C, temperature control method is changed to temperature control by power control, at this time
Start to be filled with argon gas with the rate of 50L/min；When temperature-control heat couple temperature is increased to 1560 DEG C, when ar pressure reaches 60kPa,
Temperature rise period terminates；
C. the melting stage：After temperature rise period terminates 50min, temperature-control heat couple temperature is raised to 1564 DEG C, at this temperature
Silicon material is completely melt after heat preservation 768min；
D. the directional solidification stage：After silicon material is melted completely, silica crucible declines 60mm with the rate of 2.5mm/min, at this
30L/min argon gas flow regimes are kept in the process；Later, temperature-control heat couple temperature is stablized at 1478 DEG C, with 0.1mm/min's
Drop-down rate is oriented solidification；
E. cooling stage：After directional solidification, cooled down with the rate of temperature fall of 1.5 DEG C/min, takes out silicon ingot after cooling.
The quality that feeds in the step A is 400kg.
The present invention selects the top skin of polycrystalline silicon ingot casting/purification process generation, edge skin material as raw material, utilizes electromagnetic induction coupling
Migration and the enrichment environment for closing directional solidification technique structure hard inclusions, make hard inclusions finally be enriched in ingot casting surface, into
And be removed, high purity silicon ingot is obtained, the significant effect of hard inclusions is removed using this method.
Specific implementation mode
The present invention is further described with reference to embodiments：
Embodiment 1
The method of hard inclusions, specifically includes following steps in a kind of electromagnetic induction directional solidification divided silicon：
A. it feeds：It is packed into silica crucible and contains SiC and Si3N4The polycrystalline silicon ingot casting of hard inclusions/purification process generates
Top cladding, the content of silicon is 90wt% in raw material, and charging quality is 400kg；
B. the temperature rise period：After charging, equipment vacuumizes, and is started to warm up after vacuum degree reaches 15Pa.Starting stage
It is power heating, the frequency of induction coil is 3000Hz, and changed power is 10kW (10min) -30kW (60min) -60kW
(16min)-100kW.When temperature-control heat couple temperature is 1120 DEG C, temperature control method is changed to temperature control by power control.At this time
Start to be filled with argon gas with the rate of 50L/min.When temperature-control heat couple temperature is increased to 1560 DEG C, when ar pressure reaches 60kPa,
Temperature rise period terminates；
C. the melting stage：After temperature rise period terminates 50min, temperature-control heat couple temperature is raised to 1564 DEG C, at this temperature
Silicon material is completely melt after heat preservation 768min；
D. the directional solidification stage：After silicon material is melted completely, silica crucible declines 60mm with the rate of 2.5mm/min.At this
30L/min argon gas flow regimes are kept in the process.Later, temperature-control heat couple temperature is stablized at 1478 DEG C, with 0.1mm/min's
Drop-down rate is oriented solidification；
E. cooling stage：After directional solidification, cooled down with the rate of temperature fall of 1.5 DEG C/min, takes out silicon ingot after cooling.
Embodiment 2
In a kind of electromagnetic induction directional solidification divided silicon described in this implementation each step of the method for hard inclusions with
Identical in embodiment 1, different technical parameters are：The content of silicon is 95wt% in raw material.
Embodiment 3
In a kind of electromagnetic induction directional solidification divided silicon described in this implementation each step of the method for hard inclusions with
Identical in embodiment 1, different technical parameters are：The content of silicon is 99wt% in raw material.
Finally it should be noted that：The above embodiments are only used to illustrate the technical solution of the present invention., rather than its limitations；To the greatest extent
Present invention has been described in detail with reference to the aforementioned embodiments for pipe, it will be understood by those of ordinary skill in the art that：Its according to
So can with technical scheme described in the above embodiments is modified, either to which part or all technical features into
Row equivalent replacement；And these modifications or replacements, various embodiments of the present invention technology that it does not separate the essence of the corresponding technical solution
The range of scheme.
Claims (2)
1. a kind of method of hard inclusions in electromagnetic induction directional solidification divided silicon, it is characterized in that：Include the following steps：
A. it feeds：It is packed into silica crucible and contains SiC and Si3N4What the polycrystalline silicon ingot casting or purification process of hard inclusions generated
Cladding is pushed up, the content of silicon is 90-99wt% in raw material；
B. the temperature rise period：After charging, equipment vacuumizes, and is started to warm up after vacuum degree reaches 15Pa, and the starting stage is work(
Rate heats up, and the frequency of induction coil is 3000Hz, and changed power is 10kW (10min) -30kW (60min) -60kW (16min) -
100kW；When temperature-control heat couple temperature be 1120 DEG C when, temperature control method is changed to temperature control by power control, start at this time with
The rate of 50L/min is filled with argon gas；When temperature-control heat couple temperature is increased to 1560 DEG C, when ar pressure reaches 60kPa, rank of heating up
Section terminates；
C. the melting stage：After temperature rise period terminates 50min, temperature-control heat couple temperature is raised to 1564 DEG C, is kept the temperature at this temperature
Silicon material is completely melt after 768min；
D. the directional solidification stage：After silicon material is melted completely, silica crucible declines 60mm with the rate of 2.5mm/min, in the process
Middle holding 30L/min argon gas flow regimes；Later, temperature-control heat couple temperature is stablized at 1478 DEG C, with the drop-down of 0.1mm/min
Rate is oriented solidification；
E. cooling stage：After directional solidification, cooled down with the rate of temperature fall of 1.5 DEG C/min, takes out silicon ingot after cooling.
2. the method for carbon, nitrogen impurity in a kind of removal polysilicon according to claim 1, it is characterized in that：In the step A
Charging quality is 400kg.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1569629A (en) * | 2003-07-22 | 2005-01-26 | 龚炳生 | Method of manufacturing a photovoltaic silicon |
| CN1873062A (en) * | 2006-05-06 | 2006-12-06 | 大连理工大学 | Method for preparing polysilicon in high purity in use for solar cell |
| CN101289188A (en) * | 2008-05-30 | 2008-10-22 | 大连理工大学 | Process and device for removing phosphorus and metal impurities in polycrystalline silicon |
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| CN102173424A (en) * | 2011-01-31 | 2011-09-07 | 大连理工大学 | Method and equipment for removing phosphorus and metal impurities in ganister sand through vacuum induction melting |
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| CN102976335A (en) * | 2012-12-13 | 2013-03-20 | 青岛隆盛晶硅科技有限公司 | Method and apparatus for purifying polycrystalline silicon through rotation and blow induced inversion solidification |
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