CN112853481A - Preparation method and preparation device of high-purity polycrystalline silicon ingot for cylindrical semiconductor manufacturing process - Google Patents
Preparation method and preparation device of high-purity polycrystalline silicon ingot for cylindrical semiconductor manufacturing process Download PDFInfo
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- CN112853481A CN112853481A CN202011622914.3A CN202011622914A CN112853481A CN 112853481 A CN112853481 A CN 112853481A CN 202011622914 A CN202011622914 A CN 202011622914A CN 112853481 A CN112853481 A CN 112853481A
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- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B28/00—Production of homogeneous polycrystalline material with defined structure
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- C30B28/06—Production of homogeneous polycrystalline material with defined structure from liquids by normal freezing or freezing under temperature gradient
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- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
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Abstract
The invention provides a preparation method and a preparation device of a high-purity polycrystalline silicon ingot for a cylindrical semiconductor manufacturing process, wherein the method comprises the following steps: the method comprises the following steps of (1) filling a polycrystalline silicon raw material required by preparation of a cylindrical polycrystalline silicon ingot between an inner-layer structure and an outer-layer structure of a double-layer round crucible, and putting the double-layer round crucible filled with the polycrystalline silicon raw material into an ingot furnace; vacuumizing the ingot furnace, and turning on a heater for heating until the polycrystalline silicon raw material is completely melted into liquid; the temperature in the double-layer round crucible is gradually raised from the bottom of the round crucible to form a temperature gradient so that the polycrystalline silicon raw material which is melted into liquid is gradually crystallized and solidified; and after the crystallization and solidification are finished, annealing and cooling to obtain the prepared cylindrical polycrystalline silicon ingot. According to the scheme, the polycrystalline silicon ingot is cylindrical after being produced, the batch charging amount can be greatly reduced when the cylindrical polycrystalline silicon ingot is used for producing annular polycrystalline silicon with the same size, meanwhile, the prepared cylindrical polycrystalline silicon ingot has better quality, and the melting time and the energy consumption of polycrystalline silicon raw materials are lower in the preparation process.
Description
Technical Field
The invention relates to the field of preparation of high-purity polycrystalline silicon ingots for semiconductor manufacturing processes, in particular to a preparation method and a preparation device of high-purity polycrystalline silicon ingots for cylindrical semiconductor manufacturing processes.
Background
The silicon ring for the current large-size semiconductor technology is mainly processed and manufactured by a polycrystalline silicon square ingot, and because the appearance of the silicon ring is different from that of the polycrystalline silicon square ingot, four corners and the central part of the silicon material of the square ingot need to be removed in actual production, so that the silicon material is more wasted in processing, and the production cost is high. In addition, the existing ingot casting process has inherent defects that the horizontal direction velocity of a long grain boundary surface is inconsistent due to the fact that the difference of the distance between the edge and the center of the silicon ingot from a heater is large and a temperature gradient exists in the horizontal direction, and the quality is influenced due to the fact that impurities in solid crystals are uneven due to segregation of the impurities.
Disclosure of Invention
In order to solve the technical problems in the background art, the present application provides a method and an apparatus for preparing a high purity polysilicon ingot for a cylindrical semiconductor process.
The technical scheme of the first aspect of the invention provides a preparation method of a high-purity polycrystalline silicon ingot for a cylindrical semiconductor manufacturing process, which comprises the following steps:
the method comprises the following steps of (1) filling a polycrystalline silicon raw material required by preparation of a cylindrical polycrystalline silicon ingot between an inner-layer structure and an outer-layer structure of a double-layer round crucible, and putting the double-layer round crucible filled with the polycrystalline silicon raw material into an ingot furnace;
vacuumizing the ingot furnace until the pressure in the ingot furnace is lower than a first preset pressure;
heating and melting: heating the polycrystalline silicon raw material in the double-layer round crucible through the ingot furnace until the polycrystalline silicon raw material in the double-layer round crucible is completely changed into molten liquid;
cooling and solidifying: enabling the molten liquid in the double-layer round crucible to start to solidify upwards from the bottom of the double-layer round crucible until the molten liquid in the double-layer round crucible is completely solidified;
annealing and cooling: and annealing and cooling the solidified solid to obtain the cylindrical polycrystalline silicon ingot.
In the above technical solution, preferably, the step of heating and melting specifically includes:
opening a heater of the ingot furnace for heating, introducing argon into the double-layer round crucible when the temperature in the ingot furnace is within a first preset temperature range, and maintaining the pressure in the ingot furnace within a second preset pressure range after the pressure in the ingot furnace reaches the second preset pressure range;
and continuously heating by using the heater of the ingot furnace, and keeping the temperature in the ingot furnace constant after the temperature in the ingot furnace reaches a second preset temperature range until all the polycrystalline silicon raw materials in the double-layer round crucible become molten liquid.
In the above technical solution, preferably, the step of cooling and solidifying specifically includes: and reducing the heating power of a heater of the ingot furnace, so that the temperature in the ingot furnace is reduced, opening a heat preservation cage of the ingot furnace for heat dissipation after the temperature in the ingot furnace is reduced to a third preset temperature range, and simultaneously controlling the temperature in the double-layer round crucible to gradually rise along the upward direction vertical to the bottom of the double-layer round crucible to form a temperature gradient so that the molten liquid in the double-layer round crucible starts to be upwards solidified from the bottom of the double-layer round crucible until the molten liquid in the double-layer round crucible is completely solidified.
In the above technical solution, preferably, the annealing and cooling step specifically includes:
when the temperature in the ingot furnace is reduced to a fourth preset temperature range, closing the heat preservation cage to start annealing, and simultaneously controlling the heating power of a heater of the ingot furnace to reduce the temperature in the ingot furnace to a fifth preset temperature range when the annealing is finished;
and closing the heater of the ingot furnace, opening the heat preservation cage of the ingot furnace at a preset speed rate to start cooling, and ending cooling until the temperature in the ingot furnace is reduced to a sixth preset temperature range.
In the above technical solutions, preferably, the first preset pressure is less than or equal to 0.001 mbar; the first preset temperature range is 1125-1225 ℃, the second preset pressure range is 550mbar-650mbar, the second preset temperature range is 1500 ℃ -1600 ℃, the third preset temperature range is 1370 ℃ -1470 ℃, the fourth preset temperature range is 1250 ℃ -1350 ℃, the fifth preset temperature range is 1050 ℃ -1150 ℃, and the sixth preset temperature range is 300 ℃ -400 ℃.
In the above technical solution, preferably, the method for preparing a high purity polycrystalline silicon ingot for a cylindrical semiconductor manufacturing process further includes: before the step of filling the polycrystalline silicon raw material into the double-layer round crucible, a film release layer is arranged on the inner wall of a cavity surrounded by the inner-layer structure, the outer-layer structure and the bottom wall of the double-layer round crucible.
Preferably, the release layer is a silicon nitride layer, and the silicon nitride layer is coated on the inner wall of the cavity surrounded by the inner-layer structure, the outer-layer structure and the bottom wall of the double-layer round crucible in a spraying or brushing way.
Further, the double-layer round crucible is made of quartz.
In any of the above technical solutions, preferably, when the inner layer structure of the double-layer round crucible is a hollow structure or a solid structure, and the inner layer structure of the double-layer round crucible is a hollow structure, the method for preparing a high-purity polycrystalline silicon ingot for a cylindrical semiconductor process further includes:
before the step of filling the polycrystalline silicon raw material into the double-layer round crucible, a reinforced inner layer is arranged in an inner layer structure of the double-layer round crucible, and the reinforced inner layer can be an isostatic graphite lining or a lining made of other quartz materials.
In the above technical solution, preferably, before the step of placing the double-layer round crucible containing the polycrystalline silicon raw material into the ingot furnace, the method further comprises: and a circle of detachable guard plate is arranged on the outer side wall of the double-layer round crucible along the circumferential direction.
Preferably, the shield is an isostatic graphite shield.
The technical scheme of the second aspect of the invention provides a preparation device of a high-purity polycrystalline silicon ingot for a cylindrical semiconductor manufacturing process, which comprises the following steps:
an ingot furnace;
the double-layer round crucible comprises an inner layer structure and an outer layer structure which are arranged at intervals, and polycrystalline silicon raw materials required by preparing the cylindrical polycrystalline silicon ingot can be loaded between the inner layer structure and the outer layer structure of the double-layer round crucible, wherein the double-layer round crucible can be placed in the ingot furnace and heated by the ingot furnace.
Preferably, the double-layered round crucible is made of quartz.
In the above technical solution, preferably, a release layer is disposed on an inner wall of a cavity surrounded by the inner and outer layer structures and the bottom wall of the double-layer round crucible. The stripping layer is preferably a silicon nitride layer.
In any of the above technical solutions, preferably, a ring of detachable guard plates is mounted on the outer side wall of the double-layer round crucible along the circumferential direction, and the guard plates are preferably isostatic graphite guard plates.
In any one of the above technical solutions, preferably, the inner layer structure of the double-layer circular crucible is a hollow structure or a solid structure, and when the inner layer structure of the double-layer circular crucible is a hollow structure, a reinforcing lining is placed in the inner layer structure of the double-layer circular crucible, and the reinforcing lining is used for preventing the inner layer structure of the double-layer circular crucible from softening and collapsing. Preferably, the reinforcing liner is an isostatic graphite liner.
Preferably, the reinforcing lining is a graphite rod or a graphite barrel.
According to the preparation method and the preparation device of the cylindrical high-purity polycrystalline silicon ingot for the semiconductor process, the circular double-layer crucible is adopted to prepare the polycrystalline silicon ingot for the semiconductor process, so that after the polycrystalline silicon ingot is produced, the polycrystalline silicon ingot is cylindrical instead of square, the shape of a silicon ring to be processed is consistent with that of the silicon ingot, and therefore when the produced silicon ingot is used for processing the silicon ring, the steps of removing silicon materials at the four corners and the central part of the square silicon ingot are reduced, the processing steps of annular polycrystalline silicon are simplified, the processing efficiency is improved, and the production cycle of the annular polycrystalline silicon is shortened. Meanwhile, when the annular polycrystalline silicon with the same size is produced, the feeding amount of the cylindrical polycrystalline silicon ingot can be reduced by 56% compared with that of a square polycrystalline silicon ingot, and meanwhile, after the feeding amount is reduced, the melting time and the energy consumption of polycrystalline silicon raw materials are correspondingly reduced, so that the cost of the polycrystalline silicon ingot is reduced, and the processing efficiency of the polycrystalline silicon ingot is improved. In addition, the distance difference between the edge and the center of the silicon ingot and the heater is small, so that a temperature gradient is not easily formed in the horizontal direction in the solidification process of the molten polycrystalline silicon raw material, the rate of a crystal growth interface in the horizontal direction is consistent, and the quality of the cylindrical polycrystalline silicon ingot is ensured.
It should be understood that the statements herein reciting aspects are not intended to limit the critical or essential features of any embodiment of the invention, nor are they intended to limit the scope of the invention. Other features of the present invention will become apparent from the following description.
Drawings
The above and other features, advantages and aspects of various embodiments of the present invention will become more apparent by referring to the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, like or similar reference characters designate like or similar elements, and wherein:
FIG. 1 is a schematic flow chart showing a method for preparing a high purity multicrystalline silicon ingot for a cylindrical semiconductor process according to a first embodiment of the present invention;
FIG. 2 is a schematic flow chart showing a method for preparing a high purity multicrystalline silicon ingot for a cylindrical semiconductor process according to a second embodiment of the present invention;
FIG. 3 is a schematic structural view showing that the inner layer structure of a double-layer round crucible provided by an embodiment of the invention is a hollow structure;
FIG. 4 is a schematic structural view showing that the inner layer structure of a double-layer round crucible provided by an embodiment of the invention is a solid structure;
FIG. 5 is a schematic view showing a structural state of a double-layer round crucible provided by an embodiment of the invention in a use state;
fig. 6 is a flow chart showing a method for preparing a high purity multicrystalline silicon ingot for a cylindrical semiconductor process according to a preferred embodiment of the present invention.
Wherein, the correspondence between the reference numbers and the part names in fig. 3 to 5 is:
1 double-layer round crucible, 12 outer layer structure, 14 inner layer structure, 16 demoulding layer, 2 reinforcing lining, 3 protective plate and 4 polysilicon raw material.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The method and apparatus for preparing a high purity polycrystalline silicon ingot for a cylindrical semiconductor process according to an embodiment of the present invention will be described with reference to fig. 1 to 6.
As shown in fig. 1, embodiment 1 of the present invention provides a method for preparing a high purity polycrystalline silicon ingot for a cylindrical semiconductor process, the method comprising the steps of:
s102, filling a polycrystalline silicon raw material required by preparing a cylindrical polycrystalline silicon ingot between an inner-layer structure and an outer-layer structure of a double-layer round crucible, and putting the double-layer round crucible filled with the polycrystalline silicon raw material into an ingot furnace;
s104, vacuumizing the ingot furnace until the pressure in the ingot furnace is lower than a first preset pressure;
s106, heating the polycrystalline silicon raw material in the double-layer round crucible through the ingot furnace until the polycrystalline silicon raw material in the double-layer round crucible is completely changed into molten liquid;
s108, enabling the molten liquid in the double-layer circular crucible to start to solidify upwards from the bottom of the double-layer circular crucible until the molten liquid in the double-layer circular crucible is completely solidified;
s110: and annealing and cooling the solidified solid to obtain the cylindrical polycrystalline silicon ingot.
According to the preparation method of the high-purity polycrystalline silicon ingot for the cylindrical semiconductor manufacturing process, the structure of the double-layer round crucible can be determined in advance, the double-layer round crucible is required to comprise an inner layer structure and an outer layer structure which are arranged at intervals, namely the double-layer round crucible comprises an inner layer structure and an outer layer structure which are arranged at intervals along the radial direction, and when the preparation method is used, polycrystalline silicon raw materials required for preparing the cylindrical polycrystalline silicon ingot can be filled between the inner layer structure and the outer layer structure of the double-layer round crucible. According to the preparation method, the circular double-layer crucible is adopted to prepare the polycrystalline silicon ingot, so that the polycrystalline silicon ingot is cylindrical instead of square after being produced, the shape of the silicon ring to be processed is consistent with that of the silicon ingot, and when the produced silicon ingot is used for processing the silicon ring, the steps of removing silicon materials at the four corners and the central part of the square silicon ingot are reduced, so that the processing steps of annular polycrystalline silicon are simplified, the processing efficiency is improved, and the production period of the annular polycrystalline silicon is shortened. Meanwhile, when the annular polycrystalline silicon with the same size is produced, the material input of the cylindrical polycrystalline silicon ingot can be reduced by 56% compared with the material input of a square polycrystalline silicon ingot. For example, when producing and processing a silicon ring with an outer diameter of 600mm, an inner diameter of 400mm and a height of 300mm, 251kg of silicon material is needed in the existing square ingot production, and only 110kg is needed in the production of a cylindrical polycrystalline silicon ingot. Meanwhile, after the material feeding amount is reduced, the melting time and the energy consumption of the polycrystalline silicon raw materials are correspondingly reduced, so that the cost of the polycrystalline silicon ingot is reduced, and the processing efficiency of the polycrystalline silicon ingot is improved. In addition, the distance difference between the edge and the center of the silicon ingot and the heater is small, so that a temperature gradient is not easily formed in the horizontal direction in the solidification process of the molten polycrystalline silicon raw material, the rate of a crystal growth interface in the horizontal direction is consistent, and the quality of the cylindrical polycrystalline silicon ingot is ensured.
Wherein, the inner and outer layer structures of the double-layer round crucible are arranged at intervals along the inner and outer directions.
The preparation method of the high-purity polycrystalline silicon ingot for the cylindrical semiconductor manufacturing process further comprises the following steps of: the double-layer round crucible is prepared from quartz, and comprises an inner layer structure and an outer layer structure which are arranged at intervals, wherein the double-layer round crucible can be prepared by adopting a pour-grouting process or a grouting process. Wherein, can prepare the double-deck round crucible that the inner layer structure is hollow through the mode of slip casting, overall dimension can rationally set up according to current crucible size during preparation, simultaneously, because of needs drawing die, the unilateral drawing die inclination of keeping certain distance at least in the bottom of outer diameter structure. The double-layer round crucible with the solid structure as the inner layer structure can be prepared by the injection-coagulation process, and the inner layer structure and the outer layer structure need certain drawing design for drawing.
Of course, the double-layer round crucible can be cast ingot first and then formed by using a lathe, and in addition, the double-layer round crucible can be prepared and formed by adopting an injection solidification process first and then the size and the shape of the double-layer round crucible are modified by using the lathe.
As shown in fig. 2, embodiment 2 of the present invention provides a method for preparing a high purity polycrystalline silicon ingot for a cylindrical semiconductor manufacturing process, comprising the steps of:
s202, selecting a double-layer round crucible prepared from quartz, wherein the double-layer round crucible comprises an inner layer structure and an outer layer structure which are arranged at intervals, and the inner layer structure of the double-layer round crucible is a hollow structure;
s204, spraying or brushing a silicon nitride layer on the inner wall of a cavity surrounded by the inner-layer structure, the outer-layer structure and the bottom wall of the double-layer round crucible to serve as a stripping layer;
s206, placing an isostatic pressing graphite lining in the inner layer structure of the double-layer round crucible;
s208, mounting a circle of detachable isostatic pressing graphite guard plate on the outer side wall of the double-layer round crucible along the circumferential direction;
s210, filling a polycrystalline silicon raw material required by preparing a cylindrical polycrystalline silicon ingot between an inner-layer structure and an outer-layer structure of a double-layer round crucible, and putting the double-layer round crucible filled with the polycrystalline silicon raw material into an ingot furnace;
s212, vacuumizing the ingot furnace until the pressure in the ingot furnace is lower than a first preset pressure; the first predetermined pressure is substantially 0.001 mbar;
s214, heating the polycrystalline silicon raw material in the double-layer round crucible through the ingot furnace until the polycrystalline silicon raw material in the double-layer round crucible is completely changed into molten liquid;
s216, enabling the molten liquid in the double-layer round crucible to start to solidify upwards from the bottom of the double-layer round crucible until the molten liquid in the double-layer round crucible is completely solidified;
and S218, annealing and cooling the solidified solid to obtain the cylindrical polycrystalline silicon ingot.
In this embodiment, the double-layered round crucible can be prepared in advance by a slip casting process. The silicon nitride layer is arranged on the inner wall of the cavity formed by the inner and outer layer structures and the bottom wall of the double-layer round crucible, and the silicon nitride layer can be used for demoulding, so that the silicon ingot solidified by crystallization is more conveniently separated from the crucible. Meanwhile, the silicon nitride layer also plays a role in isolating the crucible from the silicon material, and the crucible is prevented from being in direct contact with the silicon material in the heating process, so that the increase of impurities of the silicon ingot caused by the crucible is avoided. And the isostatic pressing graphite lining can prevent the hollow inner layer structure from collapsing when in use, and plays a role in supporting and reinforcing the inner layer structure. And the isostatic pressing graphite guard plate can reinforce the outer layer structure of the double-layer round crucible, so that the overall strength of the double-layer round crucible is improved.
In the above two embodiments, preferably, the heating and melting step S106 or S214 specifically includes:
opening a heater of the ingot furnace for heating, introducing argon (or other inert gases) into the double-layer round crucible when the temperature in the ingot furnace is within a first preset temperature range, and maintaining the pressure in the ingot furnace within a second preset pressure range after the pressure in the ingot furnace reaches the second preset pressure range;
and continuously heating by a heater of the ingot furnace, keeping the temperature in the ingot furnace constant after the temperature in the ingot furnace reaches a second preset temperature range until all the polycrystalline silicon raw materials in the double-layer round crucible become molten liquid.
In the above technical solution, preferably, the step S108 or S216 of cooling and solidifying specifically includes: and reducing the heating power of a heater of the ingot furnace, reducing the temperature in the ingot furnace, opening a heat preservation cage of the ingot furnace to dissipate heat after the temperature in the ingot furnace is reduced to a third preset temperature range, and simultaneously controlling the temperature in the double-layer round crucible to gradually rise along the upward direction vertical to the bottom of the double-layer round crucible to form a temperature gradient so that the molten liquid in the double-layer round crucible starts to be upwards solidified from the bottom of the double-layer round crucible until the molten liquid in the double-layer round crucible is completely solidified.
In the above technical solution, preferably, the annealing and cooling step S110 or S216 specifically includes:
when the temperature in the ingot furnace is reduced to a fourth preset temperature range, closing the heat preservation cage to start annealing, and simultaneously controlling the heating power of a heater of the ingot furnace to reduce the temperature in the ingot furnace to a fifth preset temperature range when the annealing is finished;
and closing the heater of the ingot furnace, opening a heat preservation cage of the ingot furnace at a preset speed rate to start cooling, and ending cooling until the temperature in the ingot furnace is reduced to a sixth preset temperature range.
Further preferably, the first preset pressure is less than or equal to 0.001 mbar; the first preset temperature range is 1125-1225 ℃, the second preset pressure range is 550mbar-650mbar, the second preset temperature range is 1500 ℃ -1600 ℃, the third preset temperature range is 1370 ℃ -1470 ℃, the fourth preset temperature range is 1250 ℃ -1350 ℃, the fifth preset temperature range is 1050 ℃ -1150 ℃, and the sixth preset temperature range is 300 ℃ -400 ℃.
Example 3 of the present invention provides a method for preparing a high purity polycrystalline silicon ingot for a cylindrical semiconductor process, which is different from example 2 in that the inner layer structure of the double-layer round crucible is a solid structure, and the step of placing an isostatic graphite lining in the inner layer structure of the double-layer round crucible in example 2 is omitted. The remaining steps are the same as those in embodiment 2, and are not described herein again.
According to a second aspect of the present invention, there is provided an apparatus for preparing a high purity polycrystalline silicon ingot for a cylindrical semiconductor manufacturing process, comprising an ingot furnace (not shown in the drawings) and a double-layer round crucible 1, as shown in fig. 3 and 4, the double-layer round crucible 1 comprises a double-layer structure arranged at an interval between the inside and the outside, the double-layer structure specifically comprises an outer layer structure 12 and an inner layer structure 14, as shown in fig. 5, a polycrystalline silicon raw material 4 required for preparing a cylindrical polycrystalline silicon ingot can be loaded between the outer layer structure 12 and the inner layer structure 14 of the double-layer round crucible 1, wherein the double-layer round crucible 1 can be placed in the ingot furnace and heated by the ingot furnace.
The device for preparing the high-purity polycrystalline silicon ingot for the cylindrical semiconductor manufacturing process comprises the double-layer round crucible 1 and the ingot furnace, wherein the double-layer round crucible 1 is arranged so that the polycrystalline silicon ingot is cylindrical instead of square after being produced. Therefore, the shape of the silicon ring to be processed is consistent with that of the silicon ingot, and when the produced silicon ingot is processed into the silicon ring, the steps of removing silicon materials at the four corners and the central part of the square silicon ingot are reduced, so that the processing steps of the annular polycrystalline silicon are simplified, the processing efficiency is improved, and the production period of the annular polycrystalline silicon is shortened. And when the annular polycrystalline silicon with the same size is produced, the batch charge of the cylindrical polycrystalline silicon ingot can be greatly reduced by 56 percent compared with the batch charge of the square polycrystalline silicon ingot. For example, when producing and processing a silicon ring with an outer diameter of 600mm, an inner diameter of 400mm and a height of 300mm, 251kg of silicon material is needed in the existing square ingot production, and only 110kg is needed in the production of a cylindrical polycrystalline silicon ingot. Meanwhile, after the material feeding amount is reduced, the melting time and the energy consumption of the polycrystalline silicon raw material 4 are correspondingly reduced, so that the cost of the polycrystalline silicon ingot is reduced, and the processing efficiency of the polycrystalline silicon ingot is improved. In addition, the distance difference between the edge and the center of the silicon ingot and the heater is small, so that a temperature gradient is not easily formed in the horizontal direction in the solidification process of the molten polycrystalline silicon raw material 4, the rate of a crystal growth interface in the horizontal direction is consistent, and the quality of the cylindrical polycrystalline silicon ingot is ensured. Meanwhile, when the cylindrical polycrystalline silicon ingot is used for preparing the annular polycrystalline silicon, the step of removing silicon materials at the four corners and the central part of the square silicon ingot is reduced, so that the processing steps of the annular polycrystalline silicon are reduced, the processing efficiency is improved, and the production period of the annular polycrystalline silicon is shortened.
Preferably, the double-walled circular crucible 1 is made of quartz.
In the above technical solution, preferably, as shown in fig. 3, a release layer 16 is disposed on an inner wall of a cavity surrounded by an inner-outer layer structure and a bottom wall of the double-layer round crucible 1, and the prepared cylindrical polycrystalline silicon ingot and the crucible are more conveniently separated from each other by the release layer 16, and meanwhile, the influence of the crucible on the cylindrical polycrystalline silicon ingot can be reduced by the arrangement, and impurities in the prepared cylindrical polycrystalline silicon ingot are reduced. The release layer 16 is preferably a silicon nitride layer. Specifically, the release layer 16 may be disposed on the inner wall of the outer structure 12 and the outer wall of the inner structure 14, as well as on the inner bottom wall between the outer structure 12 and the inner structure 14.
In any of the above solutions, preferably, as shown in fig. 5, a ring of detachable shield plates 3 is mounted on the outer side wall of the double-layer round crucible 1 along the circumferential direction, and the shield plates 3 are preferably isostatic graphite shield plates. Can consolidate the lateral wall of double-deck round crucible 1 through this backplate 3, improve double-deck round crucible 1's intensity, avoid double-deck round crucible 1 to collapse the damage in the course of the work. Preferably, the sheathing 3 is formed by splicing a plurality of sheathing units. Further, the guard plate 3 is formed by splicing 4 guard plate units, and a cylindrical cavity matched with the outer side wall of the double-layer round crucible 1 is formed inside the spliced 4 guard plate units.
In any of the above solutions, preferably, as shown in fig. 3 to 5, the inner layer structure 14 of the double-layer round crucible 1 is a hollow structure, and the reinforcing lining 2 is placed in the inner layer structure 14 of the double-layer round crucible 1, and the reinforcing lining 2 is used for preventing the inner layer structure 14 of the double-layer round crucible 1 from softening and collapsing. Preferably, the reinforcing liner 2 is an isostatic graphite liner.
In another embodiment, as shown in FIG. 4, the inner layer structure 14 of the double-layer round crucible 1 is a solid structure.
Preferably, the reinforcing liner 2 is a graphite rod or cylinder.
The reinforcing lining 2, the guard plate 3 and the double-layer circular crucible 1 can be assembled into a modular structure and assembled into a whole when leaving a factory, and of course, in other embodiments, the reinforcing lining 2, the guard plate 3 and the double-layer circular crucible 1 can also be mutually independent parts and assembled on site when in use.
The method for preparing a high purity polysilicon ingot for cylindrical semiconductor manufacturing process provided by the present application is further described below with reference to an embodiment, and the method is used for preparing a polysilicon ingot for silicon ring with an outer diameter of 600mm, an inner diameter of 400mm and a height of 300mm, as shown in fig. 6, and the preparation method comprises the following steps:
s602, preparing a double-layer round crucible, wherein the prepared double-layer round crucible comprises an inner layer structure and an outer layer structure which are arranged at intervals, and the inner layer structure of the double-layer round crucible is a hollow structure;
s604, brushing a silicon nitride layer on the inner wall of a cavity surrounded by the inner-layer structure, the outer-layer structure and the bottom wall of the double-layer round crucible to serve as a stripping layer;
s606, placing an isostatic pressing graphite lining in an inner layer structure of the double-layer round crucible; the static pressure graphite lining can be a graphite rod or a graphite barrel;
s608, installing a circle of detachable isostatic pressing graphite guard plate on the outer side wall of the double-layer round crucible along the circumferential direction;
s610, filling about 110kg of polycrystalline silicon raw materials between an inner layer structure and an outer layer structure of a prepared double-layer round crucible, and putting the double-layer round crucible filled with the polycrystalline silicon raw materials into an ingot furnace;
s612, vacuumizing the ingot furnace until the pressure in the ingot furnace is lower than 0.001 mbar;
s614, opening a heater of the ingot furnace for heating, introducing argon into the double-layer round crucible when the temperature in the ingot furnace rises to 1175 ℃, and controlling the air inlet and air exhaust rates when the pressure in the ingot furnace rises to 600mbar to keep the pressure in the ingot furnace constant;
s616, continuously heating by a heater of the ingot furnace, and maintaining constant-temperature melting when the temperature in the ingot furnace is raised to 1550 ℃ until all polycrystalline silicon raw materials in the double-layer round crucible are changed into molten liquid;
s618, reducing the heating power of a heater of the ingot furnace, reducing the temperature in the ingot furnace, opening a heat preservation cage of the ingot furnace to radiate heat when the temperature in the ingot furnace is reduced to 1420 ℃, and gradually increasing the temperature in the double-layer round crucible along the upward direction vertical to the bottom of the double-layer round crucible to form a temperature gradient so that the molten liquid in the double-layer round crucible starts to be solidified upwards from the bottom of the double-layer round crucible until the molten liquid in the double-layer round crucible is completely solidified;
s620, when the temperature in the ingot furnace is reduced to 1300 ℃, closing the heat preservation cage to begin annealing, and then slowly reducing the power of the heater to enable the temperature to reach about 1100 ℃ after the annealing is finished;
and S622, closing a heater of the ingot furnace, opening a heat preservation cage at a certain speed, cooling, and taking out the annular polycrystalline silicon ingot after cooling to 350 ℃.
After the annular polycrystalline silicon ingot is prepared, a silicon ring with the required specification can be obtained through mechanical processing.
Compared with the prior art, the preparation method of the high-purity polycrystalline silicon ingot for the cylindrical semiconductor process has the following advantages: 1. the material amount is reduced by 56% when the silicon ring with the same size is produced. 2. After the feeding amount is reduced, the melting time and the energy consumption of the silicon material are reduced. 3. The design of the double-layer circular crucible reduces the horizontal temperature gradient of the long crystal boundary surface, and improves the crystal growth quality.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. A method for preparing a high-purity polycrystalline silicon ingot for a cylindrical semiconductor manufacturing process is characterized by comprising the following steps of:
the method comprises the following steps of (1) filling a polycrystalline silicon raw material required by preparation of a cylindrical polycrystalline silicon ingot between an inner-layer structure and an outer-layer structure of a double-layer round crucible, and putting the double-layer round crucible filled with the polycrystalline silicon raw material into an ingot furnace;
vacuumizing the ingot furnace until the pressure in the ingot furnace is lower than a first preset pressure;
heating and melting: heating the polycrystalline silicon raw material in the double-layer round crucible through the ingot furnace until the polycrystalline silicon raw material in the double-layer round crucible is completely changed into molten liquid;
cooling and solidifying: enabling the molten liquid in the double-layer round crucible to start to solidify upwards from the bottom of the double-layer round crucible until the molten liquid in the double-layer round crucible is completely solidified;
annealing and cooling: and annealing and cooling the solidified solid to obtain the cylindrical polycrystalline silicon ingot.
2. The method according to claim 1, wherein the silicon ingot is a silicon ingot,
the heating and melting step specifically comprises: opening a heater of the ingot furnace for heating, introducing argon into the double-layer round crucible when the temperature in the ingot furnace is within a first preset temperature range, and maintaining the pressure in the ingot furnace within a second preset pressure range after the pressure in the ingot furnace reaches the second preset pressure range; continuously heating by a heater of the ingot furnace, keeping the temperature in the ingot furnace constant after the temperature in the ingot furnace reaches a second preset temperature range until all the polycrystalline silicon raw materials in the double-layer round crucible become molten liquid;
the steps of cooling and solidifying specifically comprise: reducing the heating power of a heater of the ingot furnace, so that the temperature in the ingot furnace is reduced, opening a heat preservation cage of the ingot furnace for heat dissipation after the temperature in the ingot furnace is reduced to a third preset temperature range, and simultaneously controlling the temperature in the double-layer round crucible to gradually rise along the upward direction vertical to the bottom of the double-layer round crucible to form a temperature gradient so that the molten liquid in the double-layer round crucible starts to be solidified upwards from the bottom of the double-layer round crucible until the molten liquid in the double-layer round crucible is completely solidified;
the annealing and cooling steps specifically comprise: when the temperature in the ingot furnace is reduced to a fourth preset temperature range, closing the heat preservation cage to start annealing, and simultaneously controlling the heating power of a heater of the ingot furnace to reduce the temperature in the ingot furnace to a fifth preset temperature range when the annealing is finished; and closing the heater of the ingot furnace, opening the heat preservation cage of the ingot furnace at a preset speed rate to start cooling, and ending cooling until the temperature in the ingot furnace is reduced to a sixth preset temperature range.
3. The method according to claim 2, wherein the silicon ingot is a silicon ingot having a high purity and a high purity,
the first preset pressure is less than or equal to 0.001 mbar;
the first preset temperature range is 1125-1225 ℃, the second preset pressure range is 550mbar-650mbar, the second preset temperature range is 1500 ℃ -1600 ℃, the third preset temperature range is 1370 ℃ -1470 ℃, the fourth preset temperature range is 1250 ℃ -1350 ℃, the fifth preset temperature range is 1050 ℃ -1150 ℃, and the sixth preset temperature range is 300 ℃ -400 ℃.
4. The method of claim 1, further comprising:
before the step of filling the polycrystalline silicon raw material into the double-layer round crucible, a film release layer is arranged on the inner wall of a cavity surrounded by the inner-layer structure, the outer-layer structure and the bottom wall of the double-layer round crucible.
5. The method according to claim 4, wherein the silicon ingot is a high purity silicon ingot for a cylindrical semiconductor process,
the demoulding layer is a silicon nitride layer, and the silicon nitride layer is coated on the inner wall of the cavity surrounded by the inner-layer structure, the outer-layer structure and the bottom wall of the double-layer round crucible in a spraying or brushing way; and/or
The double-layer round crucible is made of quartz.
6. The method for preparing a high purity multicrystalline silicon ingot for cylindrical semiconductor process as set forth in any one of claims 1 to 5, wherein the inner layer structure of the double-layer round crucible is a hollow structure or a solid structure, and when the inner layer structure of the double-layer round crucible is a hollow structure, the method for preparing a high purity multicrystalline silicon ingot for cylindrical semiconductor process further comprises:
and before the step of filling the polycrystalline silicon raw material into the double-layer round crucible, placing a reinforced lining in the inner layer structure of the double-layer round crucible.
7. The method for preparing a high purity multicrystalline silicon ingot for cylindrical semiconductor process according to any one of claims 1 to 5, further comprising, before the step of placing the double-layered round crucible containing the polycrystalline silicon raw material into the ingot furnace:
and a circle of detachable guard plate is arranged on the outer side wall of the double-layer round crucible along the circumferential direction.
8. A preparation apparatus of high-purity polycrystalline silicon ingot for cylindrical semiconductor process is characterized by comprising:
an ingot furnace;
the double-layer round crucible comprises an inner layer structure and an outer layer structure which are arranged at intervals, and polycrystalline silicon raw materials required by preparing the cylindrical polycrystalline silicon ingot can be loaded between the inner layer structure and the outer layer structure of the double-layer round crucible, wherein the double-layer round crucible can be placed in the ingot furnace and heated by the ingot furnace.
9. The apparatus according to claim 8, wherein the apparatus further comprises a control unit for controlling the rotation of the rotating shaft,
the double-layer round crucible is made of quartz; and/or
A demoulding layer is arranged on the inner wall of the cavity surrounded by the inner-layer structure, the outer-layer structure and the bottom wall of the double-layer round crucible; and/or
A circle of detachable guard plate is arranged on the outer side wall of the double-layer round crucible along the circumferential direction; and/or
The inner layer structure of the double-layer round crucible is of a hollow structure or a solid structure, and when the inner layer structure of the double-layer round crucible is of a hollow structure, a reinforcing lining is placed in the inner layer structure of the double-layer round crucible.
10. The apparatus for preparing a high purity multicrystalline silicon ingot for cylindrical semiconductor process as set forth in claim 9,
the guard plate is an isostatic pressing graphite guard plate, and/or the stripping layer is a silicon nitride layer, and/or the reinforcing lining is an isostatic pressing graphite lining.
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