CN113463182B - Method for drawing silicon single crystal rod - Google Patents
Method for drawing silicon single crystal rod Download PDFInfo
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- CN113463182B CN113463182B CN202110767665.5A CN202110767665A CN113463182B CN 113463182 B CN113463182 B CN 113463182B CN 202110767665 A CN202110767665 A CN 202110767665A CN 113463182 B CN113463182 B CN 113463182B
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- 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
- C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
- C30B15/02—Single-crystal growth by pulling from a melt, e.g. Czochralski method adding crystallising materials or reactants forming it in situ to the melt
- C30B15/04—Single-crystal growth by pulling from a melt, e.g. Czochralski method adding crystallising materials or reactants forming it in situ to the melt adding doping materials, e.g. for n-p-junction
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- 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
- C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
- C30B15/002—Continuous growth
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- 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
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/02—Elements
- C30B29/06—Silicon
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Abstract
The embodiment of the invention discloses a method for drawing a single crystal silicon rod and the single crystal silicon rod, wherein the method comprises the following steps: placing a polysilicon molten material with set mass and a dopant with first preset mass in a quartz crucible, heating and melting to form silicon melt, descending seed crystals to the liquid level of the silicon melt, and drawing a first single crystal silicon rod section with first preset length; after the first monocrystalline silicon rod section is cooled, the first monocrystalline silicon rod section is moved out of a crystal pulling furnace and is cut along the thin neck of the first monocrystalline silicon rod section to obtain the residual seed crystal; lowering the residual seed crystal to the liquid level of the residual silicon melt, and drawing the crystal with a horizontal shoulder; lifting the crystal to a sub-furnace chamber for cooling, and then placing a second preset mass of the dopant at a horizontal shoulder of the crystal; pulling a second single crystal silicon rod segment of a second predetermined length by lowering the crystal until the crystal is completely immersed in the remaining silicon melt for melting.
Description
Technical Field
The embodiment of the invention relates to the technical field of manufacturing of single crystal silicon rods, in particular to a method for drawing a single crystal silicon rod and the single crystal silicon rod.
Background
Single crystal silicon rods are mostly produced by the Czochralski (Czochralski) method, also referred to as the Czochralski method. The method uses the condensation crystallization driving principle of melt, and at the interface of solid and liquid, the phase change from liquid to solid is generated due to the temperature drop of the melt. In the method, the solid polycrystalline silicon melt is placed in a quartz crucible and heated to melt the polycrystalline silicon melt in the quartz crucible, and then the dislocation-free silicon single crystal rod is finally pulled through the processes of seeding, necking, shouldering, diameter equalization, ending and the like.
On the other hand, the silicon single crystal rod may be classified into a P-type silicon single crystal rod and an N-type silicon single crystal rod according to the difference of the dopant. In addition, taking a P-type single crystal silicon rod as an example, the P-type single crystal silicon rod can be further divided into a lightly doped P + single crystal silicon rod and a heavily doped P + + single crystal silicon rod according to the content of the dopant. The existing method for producing the P-type single crystal silicon rod is to put boron as a dopant and a polycrystalline silicon melt into a quartz crucible at the same time for heating and melting so as to change the characteristics of the single crystal silicon rod.
However, in actual production, customers often make different demands, for example, only a specified length of a lightly doped P + single crystal silicon rod or a heavily doped P + + single crystal silicon rod is needed, in which case, if only a short length of the lightly doped P + single crystal silicon rod or the heavily doped P + + single crystal silicon rod is pulled, costs such as a quartz crucible, productivity, etc. may be increased; or if a long length of lightly doped P + single crystal silicon rod or heavily doped P + + single crystal silicon rod is still being pulled, the portion of the single crystal silicon rod that is not in customer demand is wasted.
Disclosure of Invention
In view of the above, embodiments of the present invention are intended to provide a method for pulling a single crystal silicon rod and a single crystal silicon rod; the method can realize that two sections of monocrystalline silicon rod sections which respectively contain lightly doped P + and heavily doped P + + and have different lengths are drawn on the same monocrystalline silicon rod by utilizing one seed crystal, has simple process operation, meets the product requirements of different customers, avoids the waste of the monocrystalline silicon rod, and reduces the production cost.
The technical scheme of the embodiment of the invention is realized as follows:
in a first aspect, an embodiment of the present invention provides a method for pulling a single crystal silicon rod, where the method includes:
placing a polycrystalline silicon melt with set mass and a dopant with first preset mass in a quartz crucible, heating and melting to form silicon melt, descending seed crystals to the liquid level of the silicon melt, and drawing a first monocrystalline silicon rod section with first preset length;
after the first monocrystalline silicon rod section is cooled, the first monocrystalline silicon rod section is moved out of a crystal pulling furnace and is cut along the thin neck of the first monocrystalline silicon rod section to obtain the residual seed crystal;
lowering the remaining seed crystal to the liquid level of the remaining silicon melt to draw a crystal with a horizontal shoulder;
lifting the crystal to a sub-furnace chamber for cooling, and then placing a second preset mass of the dopant at a horizontal shoulder of the crystal;
and pulling a second single crystal silicon rod segment of a second predetermined length by lowering the crystal until the crystal is melted by complete immersion in the remaining silicon melt.
In a second aspect, the embodiment of the present invention provides a single crystal silicon rod, which is prepared according to the drawing method of the first aspect.
The embodiment of the invention provides a method for drawing a single crystal silicon rod and the single crystal silicon rod; by the drawing method, a first monocrystalline silicon rod section which is lightly doped with P + can be drawn firstly, the length of the first monocrystalline silicon rod section can be controlled to be a first preset length, after the first monocrystalline silicon rod section is drawn and moved out of a crystal pulling furnace, the remaining seed crystal can be obtained by cutting along the thin neck of the first monocrystalline silicon rod section, then the remaining seed crystal is descended to the liquid level of the remaining silicon melt, a crystal with a horizontal shoulder is grown at the tail end of the remaining seed crystal, the dopant which needs to be replenished subsequently is placed at the horizontal shoulder of the crystal, the dopant which needs to be replenished is fully immersed in the remaining silicon melt by descending the crystal and is fully melted, a second monocrystalline silicon rod section which is heavily doped with P + + is obtained by the Czochralski method, the growth length of the second monocrystalline silicon rod section can be controlled to be a second preset length, and the first monocrystalline silicon rod section and the second monocrystalline silicon rod section which respectively contain the lightly doped P + and the heavily doped P + + and have different lengths are obtained by drawing, the drawing method is simple and easy to operate, the first monocrystalline silicon rod section and the second monocrystalline silicon rod section obtained by drawing can meet different product requirements, waste of the monocrystalline silicon rods is avoided, and production cost is reduced.
Drawings
FIG. 1 is a schematic view of a crystal pulling furnace according to an embodiment of the present invention.
Fig. 2 is a schematic view of a single crystal silicon rod drawn according to a conventional embodiment of the present invention.
Fig. 3 is a schematic flow chart of a method for pulling a single crystal silicon rod according to an embodiment of the present invention.
Fig. 4 is a schematic view of a structure for monitoring a growth length of a single crystal silicon rod according to an embodiment of the present invention.
Fig. 5 is a schematic diagram of a method for obtaining the remaining seed crystal according to the embodiment of the invention.
FIG. 6 is a schematic view of a residual seed-end growth ribbon horizontal crystal provided by an embodiment of the present invention.
FIG. 7 is a schematic diagram of horizontal shoulder placement of dopants in a crystal according to an embodiment of the present invention.
FIG. 8 is a schematic view of a crystal fully immersed in a silicon melt in accordance with an embodiment of the present invention.
FIG. 9 is a schematic view of a second single crystal silicon segment according to an embodiment of the present invention.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
Referring to fig. 1, which shows a schematic structural view of a crystal pulling furnace 1 capable of implementing the technical solution of the embodiment of the present invention, as shown in fig. 1, the crystal pulling furnace 1 comprises a sub-furnace chamber 10, a guide cylinder 20, a quartz crucible 30 and a graphite heater 40 distributed around the quartz crucible 30, and is located in a main furnace chamber 50, and a polycrystalline silicon melt can be contained in the quartz crucible 30 and heated and melted by the graphite heater 40 to form a silicon melt MS.
It can be understood that the crystal pulling furnace 1 further comprises a seed cable 60, which can be used for loading M mass of polysilicon melt and M ' mass of dopant into the quartz crucible 30 when pulling the reference single crystal silicon rod S ' containing dopant, when the quartz crucible 30 is heated to melt the polysilicon melt and the dopant to form a silicon melt MS and the temperature of the silicon melt MS is stable, the seed cable 60 lowers the seed 70 to the solid-liquid interface of the silicon melt MS and starts the processes of seeding, necking, shouldering, isodiametric growth, ending and the like, so as to finally obtain a reference single crystal silicon rod S ' with a certain length, for example, taking the current reference single crystal silicon rod S ' with a diameter of 12 inches as an example, when 400 kg of polysilicon melt and a certain mass of dopant boron are added into the quartz crucible 30, the reference single crystal silicon rod S ' with a length of about 2 meters can be pulled, and it is understood that the reference single crystal silicon rod S' contains the same amount of doping at each portion thereof. The reference single crystal silicon rod S' after being pulled is shown in fig. 2.
A pulling head 80 connected to the seed crystal cable 60 is further provided at the uppermost part of the furnace body of the crystal pulling furnace 1, and the pulling head 80 is mainly used for rotating and lifting the seed crystal 70 and recording data such as displacement of the seed crystal.
It is understood that other structures not shown in FIG. 1, such as a crucible lifting device, etc., may be included in the crystal pulling furnace 1 shown in FIG. 1, and embodiments of the present invention are not specifically illustrated.
Referring to fig. 3, a crystal pulling furnace 1 is provided, which illustrates a method for pulling a single crystal silicon rod S according to an embodiment of the present invention, the method including:
s301, placing a polycrystalline silicon melt with set mass and a dopant with first preset mass in a quartz crucible, heating and melting to form silicon melt, descending seed crystals to the liquid level of the silicon melt, and drawing a first monocrystalline silicon rod section with first preset length;
s302, after the first monocrystalline silicon rod section is cooled, the first monocrystalline silicon rod section is moved out of a crystal pulling furnace and is cut along the thin neck of the first monocrystalline silicon rod section to obtain the residual seed crystals;
s303, descending the rest seed crystals to the liquid level of the rest silicon melt, and drawing crystals with horizontal shoulders;
s304, lifting the crystal to a secondary furnace chamber for cooling, and then placing the dopant with a second preset mass at the horizontal shoulder of the crystal;
s305, pulling a second single crystal silicon rod section with a second preset length by descending the crystal until the crystal is completely immersed into the residual silicon melt for melting.
It should be noted that, after adding a first predetermined mass of boron dopant into a polysilicon melt of a predetermined mass and melting the mixture to form a silicon melt, a first single crystal silicon rod segment lightly doped with P + can be pulled by the czochralski method, and after the first single crystal silicon rod segment is pulled, a supplemental dopant is added into the remaining silicon melt to be pulled to obtain a second single crystal silicon rod segment heavily doped with P + +, so that the second predetermined mass of dopant in step S304 represents the mass of boron dopant to be subsequently replenished.
According to the technical scheme shown in fig. 3, a first monocrystalline silicon rod section with a first preset length and lightly doped with P + is firstly pulled, and after the first monocrystalline silicon rod section is pulled, the first monocrystalline silicon rod section is cut short along the small diameter of the first monocrystalline silicon rod section to obtain the remaining seed crystal; secondly, growing a crystal with a horizontal shoulder at the tail end of the rest seed crystal, lifting the crystal to a secondary furnace chamber for cooling before drawing a second monocrystalline silicon rod section, and placing a dopant with second preset mass to be supplemented at the horizontal shoulder of the crystal; finally, the second heavily P + + doped monocrystalline silicon segment can be pulled by the Czochralski method by lowering the crystal until it is completely immersed in the remaining silicon melt and melted sufficiently.
For the solution shown in fig. 3, in some examples, after placing the polysilicon melt of the set mass and the dopant of the first preset mass in the quartz crucible and heating and melting to form the silicon melt, the seed crystal is lowered to the liquid level of the silicon melt and the first single crystal silicon rod section of the first preset length is pulled, including:
under the condition that the mass M of the polycrystalline silicon molten material is constant, acquiring a first preset mass M of the dopant 1 ；
Melting the polysilicon with mass M and a first preset mass M 1 After the dopant is added into a quartz crucible and heated and melted to form silicon melt, seed crystals are descended to the liquid level of the silicon melt and the first single crystal silicon rod section S is pulled 1 And monitoring the first monocrystalline silicon segment S in the isometric growth stage 1 The growth length of (a);
when the first monocrystalline silicon rod section S 1 Up to the first preset length L 1 While aligning the first monocrystalline silicon rod section S 1 And carrying out ending procedure operation.
For the above example, in some possible implementations, the obtaining of the first preset mass M of the dopant is performed under a condition that the mass M of the polysilicon frit is constant 1 The method comprises the following steps:
obtaining a first preset mass m of the dopant by calculation of formula (1) 1 ：
Wherein ρ 'represents the resistivity of the reference single crystal silicon rod S'; m 'represents the mass of the dopant in the reference single crystal silicon rod S'; ρ is a unit of a gradient 1 Represents the first monocrystalline silicon segment S 1 Of (c) is measured.
With respect to the above technical solution, before the implementation of the present invention, a reference single crystal silicon rod S 'as shown in fig. 2 is drawn in advance based on the crystal pulling furnace 1, wherein the mass of the polycrystalline silicon melt put in when drawing the reference single crystal silicon rod S' is also M, and the mass of the added dopant boron is M ', so that the resistivity ρ' of the reference single crystal silicon rod S 'can be obtained through the test, and the test method of the specific resistivity ρ' is not specifically described in the embodiment of the present invention.
Under the condition that the resistivity rho 'of the reference monocrystalline silicon rod S' is obtained through the test, the first monocrystalline silicon rod section S of the drawn lightly doped P + can be obtained through the calculation of the formula (1) 1 A first predetermined mass M of boron dopant to be added to the M-mass polysilicon melt 1 。
In the embodiment of the present invention, the first monocrystalline silicon segment S 1 Is drawn according to the requirements of the product, and therefore its resistivity ρ 1 Are known.
For the above example, in some possible implementations, the polysilicon frit material of mass M and a first predetermined mass M 1 After the dopant is added into a quartz crucible to be heated and melted to form silicon melt, seed crystals are descended to the liquid level of the silicon melt and the first single crystal silicon rod section S is drawn 1 And monitoring the first monocrystalline silicon segment S in the isometric growth stage 1 Comprises:
pulling the first monocrystalline silicon segment S by a Czochralski method 1 In the process, the first monocrystalline silicon rod section S is determined by monitoring the rising distance of the seed crystal cable in the equal-diameter growth stage 1 The growth length of (2).
Understandably, as shown in FIG. 1, a first single crystal silicon ingot is prepared using a crystal pulling furnace 1Node S 1 When the polysilicon melt is melted to the silicon melt MS and the temperature of the silicon melt MS is stabilized, the seed crystal 70 is lowered to the silicon melt surface by the pulling head 80 to perform a process operation such as seeding, and when the seeding is completed and the growth of the narrow neck is started, the seed crystal 70 gradually rises along with the rise of the seed cable 60. Thus, it will be appreciated that the distance that seed cable 60 is raised during the isometric growth phase can be used to characterize first monocrystalline silicon segment S 1 The growth length of (2).
Note that the distance by which the seed cable 60 rises can be obtained from the displacement data in the pulling head 80.
In some implementations of the invention, as shown in FIG. 4, the end of seed crystal cable 60 may also be connected to a cable 901 on spool 90, and the first monocrystalline silicon rod segment S is determined during the isometric growth phase by monitoring the distance traveled around cable 901 1 The length of growth of (1), specifically, the distance l that the rope 901 moves is pi dn obtained by the number of turns n of the rope 901 wound on the winding shaft 90 when moving and the diameter d of the winding shaft 90; of course, in the first monocrystalline silicon segment S 1 First preset length L 1 By monitoring the number of turns of rope 901 wound on spool 80, as is known
Can also control the first monocrystalline silicon bar section S 1 The growth length of (2).
Of course, for the first monocrystalline silicon segment S 1 The monitoring of the growth length is not limited to the above-mentioned method, and for example, an industrial camera or the like may be installed in an observation window (not shown) of the crystal pulling furnace 1 to monitor the first silicon ingot S in real time 1 The growth state and the growth length of (c).
As can be appreciated, during the isometric growth phase, when seed cable 60 is moved a distance l equal to first monocrystalline silicon segment S 1 First preset length L 1 Then, the first monocrystalline silicon segment S can be carried out 1 And (4) ending the process. The first single crystal silicon rod section S obtained by final drawing 1 As shown by the left diagonal filling part in fig. 5, the growth length is a first predetermined lengthL 1 。
With respect to the solution shown in FIG. 3, in some examples, as shown in FIG. 5, the first monocrystalline silicon segment is removed from the crystal pulling furnace after it has cooled and is sheared along the neck of the first monocrystalline silicon segment to obtain the remaining seed crystal. Understandably, in the first monocrystalline silicon segment S 1 After drawing is completed and cooling, the ingot is removed from the crystal pulling furnace 1 along a first monocrystalline silicon segment S 1 Is cut off at the narrow neck to obtain the remaining seed crystal 70.
For the solution shown in fig. 3, in some examples, said lowering the remaining seed crystal to the level of the remaining silicon melt to draw a crystal with a horizontal shoulder, comprising:
lowering the rest seed crystals to the liquid level of the rest silicon melt, and carrying out seeding and necking operation;
after a section of thin neck grows at the tail end of the residual seed crystal, shouldering operation is carried out, so that a horizontal shoulder grows at the tail end of the thin neck;
and after the horizontal shoulder is grown, performing a rapid ending process operation to grow a crystal S' with the horizontal shoulder at the tail end of the residual seed crystal.
It is understood that, as shown in fig. 6, after the remaining seed crystal 70 is lowered to the liquid level of the silicon melt MS for necking operation, a thin neck can be grown at the end of the remaining seed crystal 70, and after the process operations of shouldering and rapid ending are performed again, the crystal S ″ with a horizontal shoulder can be grown at the end of the remaining seed crystal 70.
For the solution shown in fig. 3, in some examples, after the lifting the crystal to a sub-furnace chamber for cooling, placing a second predetermined mass of the dopant at a horizontal shoulder of the crystal comprises:
after the crystal S "is moved to a sub-furnace chamber by lifting a seed cable and cooled, the dopant of the second predetermined mass is placed at a horizontal shoulder of the crystal S".
Understandably, as shown in FIG. 7, when the crystal S "When the furnace is lifted to the auxiliary furnace chamber and after cooling, the mass prepared in advance can be set to a second preset mass m by a charging device in the crystal pulling furnace 1 2 Is placed in the horizontal shoulder of the crystal S "(shown as a black circle).
For the above example, in some possible implementations, the second preset mass m 2 The method comprises the following steps:
according to the first monocrystalline silicon rod section S 1 The first monocrystalline silicon rod section S is obtained by calculation 1 Of (2)
Wherein D is 1 Represents the first monocrystalline silicon bar segment S 1 λ represents the density of the first monocrystalline silicon rod segment;
according to the first monocrystalline silicon rod section S 1 Mass M of 1 Calculating to obtain the mass M of the residual silicon melt in the quartz crucible 2 ＝M-M 1 ；
According to the formula (2), the first monocrystalline silicon rod section S is obtained by derivation calculation 1 Of the dopant contained in (1) 1 '：
Wherein a represents a segregation coefficient of the dopant in the silicon melt; m is 1 "represents the mass of the dopant contained in the remaining silicon melt, and m 1 ”＝m 1 -m 1 '；
Calculating to obtain the second monocrystalline silicon rod section S when the mass of the polycrystalline silicon is M according to the formula (3) 2 Corresponding doping amount m 2 '：
Where ρ is 2 Represents the second silicon single crystal bar segment S 2 Resistance ofRate;
according to the formula (4), the mass M is obtained by calculation 2 Of the dopant contained in the silicon melt of (1) 2 ”：
According to the doping amount m 2 "and doping amount m in the remaining silicon melt 1 ", calculating to obtain a second preset mass m of said dopant to be replenished 2 ＝m 2 ”-m 1 ”。
Note that since the segregation coefficient is the solubility of impurities in the solid phase/the solubility of impurities in the liquid phase, and the segregation coefficient of boron as a dopant in the silicon melt is generally 0.3, it can be derived by the inverse of the equations (2), (3) and (4): when the mass M of the remaining silicon melt is known 2 Then, a second monocrystalline silicon bar section S heavily doped with P + + is prepared 2 Mass m of boron as dopant required 2 ", so as to depend on the mass m of dopant already contained in the remaining silicon melt 1 ", calculating to obtain a second predetermined mass m of dopant to be replenished 2 。
It should be noted that, in the embodiment of the present invention, the second monocrystalline silicon segment S 2 Is drawn according to the requirements of the product, and therefore its resistivity ρ 2 Are known.
Of course, it is understood that in the embodiment of the present invention, a weighing device (not shown) may also be provided at the pull head 80 to obtain the first monocrystalline silicon segment S 1 Mass M of 1 And further according to the first monocrystalline silicon rod section S 1 Mass M of 1 Obtaining the mass M of the silicon melt remaining in the quartz crucible 2 And when the mass of the silicon melt is M 2 While drawing the second monocrystalline silicon rod section S heavily doped with P + 2 Mass m of boron as dopant 2 ", ultimately obtaining a second predetermined mass m of said dopant to be replenished 2 。
For the solution shown in fig. 3, in some examples, said pulling a second predetermined length of a second single crystal silicon rod segment after said lowering said crystal until said crystal is completely immersed in said remaining silicon melt for melting comprises:
lowering said crystal S' such that said dopant disposed in said horizontal shoulder is completely immersed in said remaining silicon melt and melted, and thereafter drawing said second single crystal silicon rod segment S 2 And monitoring the second monocrystalline silicon bar section S in the equal-diameter growth stage 2 The growth length of (a);
when the second monocrystalline silicon rod section S 2 Is the second preset length L 2 While aligning the second monocrystalline silicon rod section S 2 And carrying out ending procedure operation.
It will be appreciated that, as shown in FIG. 8, after the horizontal shoulders of the crystal S "have been placed with the boron dopant to be replenished, the process steps of the Czochralski method can be followed by lowering the crystal S" until the entire crystal S "including its horizontal shoulders is completely immersed in the remaining silicon melt to melt and the temperature of the silicon melt has stabilized: seeding, necking, shouldering, isodiametric growth and ending are continuously drawn at the tail part of the rest of the seed crystals 70 to obtain the second preset length L 2 Second monocrystalline silicon segment S 2 And the second monocrystalline silicon rod segment S 2 The doping type of the doped layer is heavily doped P + +.
For the above example, in some possible implementations, the lowering the crystal S' draws the second single crystal silicon rod segment S after the dopant placed in the horizontal shoulder is completely immersed in the remaining silicon melt and melted 2 And monitoring the second monocrystalline silicon bar section S in the equal-diameter growth stage 2 Comprises:
pulling the second monocrystalline silicon segment S by a Czochralski method 2 Meanwhile, the second monocrystalline silicon rod section S is determined by monitoring the rising distance of the seed crystal cable in the equal-diameter growth stage 2 The growth length of (c).
And drawing a first monocrystalline silicon segment S 1 Similarly, the distance that seed crystal cable 60 is raised during the isometric growth stage can be used to characterize second monocrystalline silicon segment S 2 The growth length of (2). Most preferablySecond single crystal silicon rod section S obtained by final drawing 2 As shown by the right slant line filling part in fig. 9, the growth length is a second predetermined length L 2 。
Note that the distance by which the seed cable 60 rises can be obtained from the displacement data in the pulling head 80.
The embodiment of the invention provides a single crystal silicon rod S, which is prepared by the drawing method according to the technical scheme.
As can be appreciated, the single crystal silicon rod S obtained by pulling according to the embodiment of the present invention includes a first predetermined length L 1 The first monocrystalline silicon rod section S of light doped P + 1 And a length of a first preset length L 2 The second monocrystalline silicon rod section S heavily doped with P ++ 2 The method can meet different requirements of different customers, and reduces the waste of production cost.
It can be understood that by using the pulling method provided by the embodiment of the invention, the single crystal silicon rod S can also comprise a plurality of sections of single crystal silicon rods with different doping amounts and different lengths.
It should be noted that: the technical schemes described in the embodiments of the present invention can be combined arbitrarily without conflict.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (8)
1. A method for pulling a single crystal silicon rod, the method comprising:
placing a polycrystalline silicon melt with set mass and a dopant with first preset mass in a quartz crucible, heating and melting to form silicon melt, descending seed crystals to the liquid level of the silicon melt, and drawing a first monocrystalline silicon rod section with first preset length;
after the first monocrystalline silicon rod section is cooled, the first monocrystalline silicon rod section is moved out of a crystal pulling furnace and is cut along the thin neck of the first monocrystalline silicon rod section to obtain the residual seed crystal;
lowering the remaining seed crystal to the liquid level of the remaining silicon melt to draw a crystal with a horizontal shoulder;
lifting the crystal to a sub-furnace chamber for cooling, and then placing a second preset mass of the dopant at a horizontal shoulder of the crystal;
pulling a second single crystal silicon rod segment of a second predetermined length by lowering the crystal until the crystal is completely immersed in the remaining silicon melt for melting;
the second preset mass calculating method comprises the following steps:
obtaining the mass M of the first monocrystalline silicon rod section by using a weighing method 1 ；
According to the mass M of the first monocrystalline silicon rod section 1 Calculating to obtain the mass M of the residual silicon melt in the quartz crucible 2 ＝M-M 1 ；
Calculating a mass m of the dopant contained in the first monocrystalline silicon segment according to 1 '：
Wherein a represents a segregation coefficient of the dopant in the silicon melt; m is 1 "represents the mass of the dopant contained in the remaining silicon melt, and m 1 ”＝m 1 -m 1 '，m 1 Represents the first predetermined mass, and m' represents the mass of the dopant in a reference single crystal silicon rod;
according to the following formula, calculating the doping amount M corresponding to the second monocrystalline silicon rod section when the mass of the polycrystalline silicon is M 2 '：
Where ρ is 2 Representing the resistivity of the second monocrystalline silicon segment;
the mass M is calculated from the formula 2 Of the dopant contained in the silicon melt of (1) 2 ”：
According to the doping amount m 2 "and doping amount m in the remaining silicon melt 1 ", calculating to obtain a second preset mass m of said dopant to be replenished 2 ＝m 2 ”-m 1 ”。
2. The method of claim 1, wherein after placing a set mass of polycrystalline silicon melt and a first predetermined mass of dopant in a quartz crucible and heating and melting to form a silicon melt, lowering a seed crystal to a level of the silicon melt and pulling a first single crystal silicon rod segment of a first predetermined length comprises:
under the condition that the mass M of the polycrystalline silicon molten material is certain, obtaining a first preset mass M of the dopant 1 ；
Melting the polysilicon with a mass M and a first predetermined mass M 1 After the dopant is added into a quartz crucible to be heated and melted to form silicon melt, seed crystals are descended to the liquid level of the silicon melt and the first single crystal silicon rod section S is drawn 1 And monitoring the first monocrystalline silicon segment S in the isometric growth stage 1 The growth length of (a);
when the first monocrystalline silicon rod section S 1 Up to the first preset length L 1 While aligning the first monocrystalline silicon rod section S 1 And carrying out ending procedure operation.
3. The method of claim 2, wherein the obtaining of the first predetermined mass M of the dopant is performed under a condition that the mass M of the polysilicon frit is constant 1 Comprises that：
Obtaining a first preset mass m of the dopant by calculation of formula (1) 1 ：
Wherein ρ 'represents the resistivity of the reference single crystal silicon rod S'; m 'represents the mass of the dopant in the reference single crystal silicon rod S'; rho 1 Represents the first monocrystalline silicon segment S 1 Of (c) is measured.
4. The method of claim 2 wherein the step of melting the polysilicon of mass M and the first predetermined mass M 1 After the dopant is added into a quartz crucible to be heated and melted to form silicon melt, seed crystals are descended to the liquid level of the silicon melt and the first single crystal silicon rod section S is drawn 1 And monitoring the first monocrystalline silicon segment S in the isometric growth stage 1 Comprises:
pulling the first monocrystalline silicon segment S by a Czochralski method 1 In the process, the first monocrystalline silicon rod section S is determined by monitoring the rising distance of the seed crystal cable in the equal-diameter growth stage 1 The growth length of (2).
5. A method as set forth in claim 1 wherein said lowering the remaining seed crystal to the level of the remaining silicon melt to draw the crystal with a horizontal shoulder comprises:
lowering the rest seed crystals to the liquid level of the rest silicon melt, and carrying out seeding and necking operation;
after a section of thin neck grows at the tail end of the rest seed crystal, shoulder-putting operation is carried out, so that a horizontal shoulder grows at the tail end of the thin neck;
after the horizontal shoulder is grown, a rapid ending process operation is performed to grow a crystal S' with a horizontal shoulder at the end of the remaining seed crystal.
6. The method of claim 1, wherein said lifting the crystal to a sub-furnace chamber after cooling places a second predetermined mass of the dopant at a horizontal shoulder of the crystal, comprising:
after the crystal S "is moved to a sub-furnace chamber by lifting a seed cable and cooled, the dopant of the second predetermined mass is placed at a horizontal shoulder of the crystal S".
7. The method of claim 1 wherein said drawing a second single crystal silicon rod segment of a second predetermined length after said melting by lowering said crystal until said crystal is completely immersed in said remaining silicon melt comprises:
lowering said crystal S' such that said dopant disposed in said horizontal shoulder is completely immersed in said remaining silicon melt and melted, and thereafter drawing said second single crystal silicon rod segment S 2 And monitoring the second monocrystalline silicon rod section S in the equal-diameter growth stage 2 The growth length of (a);
when the second monocrystalline silicon rod section S 2 Is the second preset length L 2 While aligning the second monocrystalline silicon rod section S 2 And carrying out ending procedure operation.
8. The method of claim 7 wherein said lowering said crystal S "draws said second single crystal silicon rod segment S after said dopant placed in said horizontal shoulder is completely immersed in said remaining silicon melt and melted 2 And monitoring the second monocrystalline silicon bar section S in the equal-diameter growth stage 2 Comprises:
pulling the second monocrystalline silicon rod section S by adopting a Czochralski method 2 In the process, the second monocrystalline silicon rod section S is determined by monitoring the rising distance of the seed crystal cable in the equal-diameter growth stage 2 The growth length of (c).
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Address after: No. 1888, Xifeng South Road, high tech Zone, Xi'an, Shaanxi 710065 Patentee after: XI'AN ESWIN SILICON WAFER TECHNOLOGY Co.,Ltd. Patentee after: Xi'an Yisiwei Material Technology Co.,Ltd. Address before: No. 1888, Xifeng South Road, high tech Zone, Xi'an, Shaanxi 710065 Patentee before: XI'AN ESWIN SILICON WAFER TECHNOLOGY Co.,Ltd. Patentee before: Xi'an yisiwei Material Technology Co.,Ltd. |
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