Method for forming unitized crucible assembly, crucible mold and unitized crucible

Abstract

To provide an unitized crucible assembly for holding a silicon melt for forming a silicon ingot, and a method for forming the same.SOLUTION: A method comprises a porous crucible mold having a channel network 20 including a bottom channel 30, an outer side wall channel 32 extended from the bottom channel and a central dam channel 34 extended from the bottom channel. Slip slurry may be added to the channel network; the liquid carrier of the slip slurry may be drawn in the mold; and the obtained green body may be sintered for forming a crucible assembly.SELECTED DRAWING: Figure 3

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Non-provisional Patent Application No. 16 / 796,482, filed February 20, 2020, and to U.S. Non-provisional Patent Application No. 16 / 796,522, filed February 20, 2020. Both applications are incorporated by reference herein in their entireties. [Technical field]

[0002] The field of the disclosure relates to methods for forming unitized crucible assemblies for holding silicon melt to form silicon ingots, and in particular to methods for forming unitized crucible assemblies having center and inner dams for use in continuous Czochralski silicon ingot growth. The field of the disclosure also relates to crucible molds and unitized crucibles. [Background technology]

[0003] Single crystal silicon ingots are prepared by the so-called Czochralski method, in which a single crystal silicon seed is contacted with a silicon melt held in a crucible. The single crystal silicon seed is pulled from the melt to pull a single crystal silicon ingot from the melt. Ingots may be prepared in a batch system, in which a charge of polycrystalline silicon is first melted in a crucible, and silicon ingots are pulled from the melt until the molten silicon in the crucible is depleted. Alternatively, ingots may be pulled in a continuous Czochralski method, in which polysilicon is intermittently or continuously added to the melt to replenish the silicon melt during ingot growth.

[0004] In the continuous Czochralski process, the crucible may be divided into separate melt zones. For example, the crucible assembly may include an outer melt zone where polycrystalline silicon is added and melted to replenish the silicon melt as the silicon ingot is grown. The silicon melt flows from the outer melt zone to a stabilization zone within the outer melt zone where the melt is thermally stabilized. The silicon melt then flows from the stabilization zone to a growth zone from which the silicon ingot is pulled.

[0005] Conventionally, a crucible assembly for growing silicon ingots by the continuous Czochralski process may include one or more nested crucibles, such as the crucible assembly shown in U.S. Pat. No. 10,450,670. Alternatively or additionally, the crucible assembly may include one or more weirs connected to the bottom of the crucible and extending upward therefrom, as disclosed in U.S. Pat. No. 8,262,797. Both types of crucible placement involve the use of alignment tools when placed in the crystal pulling hot zone to provide uniform gas flow over the crucible assembly. Both types of construction require connections to be made to the bottom of the crucible assembly (i.e., attaching the weir or crucible to the bottom of the assembly). These connections can cause the crucible assembly to deform and degrade, causing it to lose one or more tolerances.

[0006] What is needed is a crucible assembly that is resistant to deformation, can be placed in a hot zone without or with fewer alignment tools, and is more easily manufactured, and a method for preparing such a crucible assembly.

[0007] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. As such, it should be understood that these statements are to be read in this light, and not as admissions of prior art. Summary of the Invention

[0008] One aspect of the disclosure relates to a method for forming a unitized crucible assembly for holding a silicon melt to form a silicon ingot by the Czochralski process. A crucible mold is provided. The mold has a channel network including a bottom channel and an outer sidewall channel extending from the bottom channel. The channel network also includes a central weir channel extending from the bottom channel and an inner weir channel extending from the bottom channel. The central weir is disposed between the outer sidewall channel and the inner weir channel. A slip slurry is introduced into the channel network to fill the bottom channel, the outer sidewall channel, the central weir channel, and the inner weir channel with the slip slurry. The slip slurry includes silica and a liquid carrier. The liquid carrier is at least partially removed from the channel network to form a green body. The green body is removed from the crucible mold. The green body is sintered to dry and densify the green body to form the unitized crucible assembly.

[0009] Another aspect of the disclosure relates to a method for forming a unitized crucible assembly for holding a silicon melt to form a silicon ingot by the Czochralski process. A crucible mold is provided. The mold includes a porous body and a channel network disposed within the porous body. The channel network includes a bottom channel, an outer sidewall channel extending from the bottom channel, and an inner weir channel extending from the bottom channel. The inner weir channel is disposed inside the outer sidewall channel. A slip slurry is introduced into the channel network to fill the bottom channel, the outer sidewall channel, and the inner weir channel with the slip slurry. The slip slurry includes silica and a liquid carrier. The liquid carrier is drawn at least partially into the mold by capillary action to form a green body. The green body is separated from the crucible mold. The green body is sintered to dry and densify the green body and form the unitized crucible assembly.

[0010] Yet another aspect of the present disclosure relates to a crucible mold. The crucible mold includes a lower portion and an upper portion disposed above the lower portion. The upper portion forms a central weir channel and an inner weir channel. The upper and lower portions form a bottom channel and a sidewall channel fluidly connected to the bottom channel. The central weir channel and the inner weir channel extend from the bottom channel.

[0011] Yet another aspect of the present disclosure relates to a crucible assembly. The crucible assembly includes a bottom, an outer sidewall extending upward from the bottom, a central dam extending upward from the bottom, and an inner dam extending upward from the bottom. The central dam is disposed between the outer sidewall and the inner dam. The bottom, outer sidewall, central dam, and inner dam are unitized and are seamless at (1) a junction between the outer sidewall and the bottom, (2) a junction between the central dam and the bottom, and (3) a junction between the inner dam and the bottom.

[0012] Various refinements exist in the features noted in relation to the above-mentioned aspects of the disclosure. Further features may also be incorporated into the above-mentioned aspects of the disclosure as well. These refinements and additional features may exist individually or in any combination. For example, the various features described below in relation to any of the illustrated embodiments of the disclosure may be incorporated into any of the above-mentioned aspects of the disclosure alone or in any combination. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a cross-sectional view of one embodiment of a unitized crucible assembly. [Diagram 2] FIG. 2 is a perspective view of one embodiment of a crucible mold having a green body formed therein. [Diagram 3] FIG. 3 is a perspective cross-sectional view of the crucible mold and green body taken along line 3-3 of FIG. 2. [Figure 4] FIG. 2 is a plan view of a crucible mold and a green body. [Diagram 5] FIG. 5 is a cross-sectional view of the crucible mold without the green body taken along line 5-5 of FIG. [Figure 6] FIG. 6 is another cross-sectional view of the crucible mold without the green body taken along line 6-6 of FIG. [Figure 7] FIG. 2 is a cross-sectional view of a crucible mold having slip slurry poured therein. [Figure 8] FIG. 2 is another cross-sectional view of a crucible mold having slip slurry poured therein. [Figure 9] FIG. 13 is a detailed cross-sectional view of a crucible mold showing center and inner dam pegs for forming openings in the center and inner dams of the resulting crucible.

[0014] Corresponding reference characters indicate corresponding parts throughout the drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present disclosure relates to a method for forming a unitized crucible (e.g., a monolithic structure) for holding a silicon melt to form a silicon ingot by the Czochralski process. An exemplary unitized crucible assembly 5 that may be manufactured by embodiments of the present disclosure is shown in FIG. 1. The unitized crucible assembly 5 includes a bottom 17 and an outer sidewall 10 extending upwardly from the bottom 17. The crucible assembly 5 includes a central dam 24 and an inner dam 31, both of which extend upwardly from the bottom 17. The central dam 24 is disposed between the outer sidewall 10 and the inner dam 31.

[0016] In an embodiment of the present disclosure, a mold 8 (FIG. 2) is provided having a channel network 20 (FIGS. 5, 6) formed therein. The mold 8 includes an upper portion 12 and a lower portion 18 that are assembled together to form the channel network 20. As described further below, a slip is poured into the channel network 20 to form a crucible-shaped "green body" 40 (FIG. 2). The green body 40 is removed from the mold 8 and sintered to form the unitized crucible assembly 5 (FIG. 1).

[0017] 2-4, in which the mold 8 is transparent for purposes of illustration and the channel network 20 is shown with the green body 40 formed therein, the channel network 20 includes a bottom channel 30 and an outer sidewall channel 32. The channel network 20 also includes a central weir channel 34 and an inner weir channel 36, each disposed inside the outer sidewall channel 32. The central weir channel 34 is disposed between the inner weir channel 36 and the outer sidewall channel 32. As shown in FIG. 3, the outer sidewall channel 32, the central weir channel 34, and the inner weir channel 36 are fluidly connected to the bottom channel 30 (i.e., each channel of the channel network is fluidly connected to allow unitization of the resulting crucible).

[0018] The upper portion 12 of the mold 8 includes a body 49 (FIGS. 5, 6) and a flange 54 extending radially outward from the body 49. The body 49 has a lower surface 53 (i.e., the surface below the flange 54 that forms the surfaces of the bottom channel 30 and the outer sidewall channel 32).

[0019] The lower portion 18 of the mold 8 also includes a body 56. The body 56 has an upper surface 59 (i.e., the surface that forms the surface of the bottom channel 30 and the outer sidewall channel 32) and defines a recess 61 on the inside of the upper surface 59. In the illustrated embodiment, at least a portion of the lower surface 53 of the body 49 of the upper portion 12 of the mold 8 and at least a portion of the upper surface 59 of the lower portion 18 of the mold 8 are rounded to form a rounded crucible bottom 17 (FIG. 1). To assemble the mold 8, the body 49 of the upper portion 12 is lowered into the recess 61 of the lower portion 18 until the flange 54 rests on the lower portion 18. In this position, the upper portion 12 and the lower portion 18 of the mold 8 together form the bottom channel 30 and the outer sidewall channel 32.

[0020] In the illustrated embodiment, bottom channel 30 is rounded (and the resulting crucible bottom 17 (FIG. 1) is rounded). In other embodiments, bottom channel 30 may be more horizontal or completely horizontal (i.e., flat), or may be conical or inverted (e.g., with a pedestal in the middle). As shown in FIGS. 5-6, a portion of sidewall channel 32 is taller than central weir channel 34, a portion of central weir channel 34 is taller than inner weir channel 36, and a portion of central weir channel 34 is taller than inner weir channel 36. In other embodiments, the channels may have different relative heights (e.g., the heights of sidewall channel 32, central weir channel 34, and inner weir channel 36 are the same).

[0021] First and second outer sidewall channel risers 58, 60 (FIG. 2) extend through the top portion 12 and are in fluid communication with the outer sidewall channel 32. First and second central weir channel risers 64, 66 also extend through the top portion 12 and are in fluid communication with the central weir channel 34. First and second inner weir channel risers 70, 72 also extend through the top portion 12 and are in fluid communication with the inner weir channel 36. The risers 58, 60, 64, 66, 70, 72 extend through the top portion 12 to allow the channel network 20 to be filled with a slip slurry. For example, slip slurry may be added to either the first and second sidewall risers 58, 60 to fill the outer sidewall channel 32 and the bottom channel 30 with the slurry. As channels 30, 32 fill with slurry, air escapes through the corresponding risers 58, 60 that are not filled with slip slurry. Similarly, slip slurry may be added to either the first or second central weir channel risers 64, 66 and the first or second inner weir channel risers 70, 72 until the channel network 20 is filled with slip slurry (FIGS. 7-8). In the illustrated embodiment, each riser 58, 60, 64, 66, 70, 72 includes a cone portion 51 (FIG. 5) that opens into a surface 57 of the upper portion 12 of the mold 8 to facilitate injection of the slip slurry into the riser. A duct 52 below the cone portion 51 fluidly connects the cone portion 51 to the respective channel. Slip slurry may be added until the duct 52 and / or the cone portion 51 begin to fill, such that the channel network 20 is filled with slip slurry. For example, the volume of the slip slurry shrinks as the liquid carrier is drawn into the mold 8. Slip slurry disposed in one or more ducts 52 and / or cone portions 51 of the risers 58, 60, 64, 66, 70, 72 may be drawn into the channel network 20 as the slip slurry shrinks.

[0022] In general, the channels may be filled in any order that allows the channel network 20 to be filled with slip slurry before a portion of the slurry begins to solidify as a green body and allows the resulting crucible to be unitized. The arrangement of the risers 58, 60, 64, 66, 70, 72 is exemplary and other arrangements may be used unless otherwise noted. The risers 58, 60, 64, 66, 70, 72 may be openings and / or chambers formed in the upper portion 12 of the mold 8. In some embodiments, the risers 58, 60, 64, 66, 70, 72 include an opening / chamber and a liner disposed on a surface of the opening / chamber.

[0023] In some embodiments, the slip slurry added to the channel network 20 to fill the bottom channel 30, the outer sidewall channel 32, the central weir channel 34, and the inner weir channel 36 includes silica and a liquid carrier such as water. The slip slurry may also include other reagents such as a suspending agent that maintains the silica particles in suspension, including any suspending agent known to one of skill in the art. Exemplary suspending agents include polymers or organics that adsorb onto the particles (e.g., long-chain organic molecules, or other agents that accumulate a surface charge on the silica particles to reduce contact between particles). The slip slurry may include one or more binders that can optionally be burned off during sintering, as described below. Optionally, the slip slurry may include one or more release agents to facilitate separation of the mold 8 from the resulting green body 40.

[0024] Mold 8 may be made of a material that allows the liquid carrier to be removed (e.g., by capillary action) from channel network 20 to form green body 40. In some embodiments, mold 8 is made of gypsum, such as gypsum board (e.g., CaSO4·nH20, also known as plaster of Paris). In other embodiments, mold 8 is made of porous silica. Mold 8 may be a generally porous body that draws the liquid carrier into mold 8 by capillary action. In other embodiments, the liquid carrier may be drawn by a vacuum.

[0025] Once the liquid carrier is drawn from the slip slurry into the mold 8, a "green body" 40 (FIGS. 2, 3) remains within the mold 8. For example, the green body 40 may have sufficient structure to maintain its shape upon separation from the mold. For example, the moisture content of the green body may be less than about 50%, less than about 45%, at least about 30 wt%, at least about 35 wt%, at least about 40 wt%, at least about 45 wt%, between about 30 wt% and about 50 wt%, or between about 35 wt% and about 45 wt%.

[0026] Green body 40 may be further dried, such as by exposing green body 40 to an ambient of relatively low and / or controlled humidity (e.g., after green body 40 has sufficient strength, mold 8 is removed and green body 40 is exposed to an ambient of relatively low and / or controlled humidity, etc.). The terms "green body" or "green state" as used herein should not be considered in a limiting sense and generally refer to the intermediate state of the crucible after the liquid carrier has been partially withdrawn from the slip slurry and prior to sintering of the structure.

[0027] To separate the mold 8 from the green body 40, the top portion 12 of the mold 8 may be lifted from the green body 40 and from the bottom portion 18. The green body 40 may then be lifted from the bottom portion 18. The resulting green body 40 may have protrusions (not shown) extending up from the sidewalls and weirs that correspond to the riser locations (e.g., slip slurry was added to completely fill the channel network 20 such that additional amounts fill the risers). These protrusions may be ground or cut from the green body 40 or the resulting crucible assembly 5 (FIG. 1).

[0028] In some embodiments, the mold 8 may include pegs in one or more of the channels to form openings in the resulting crucible to allow molten silicon to move between various sections of the crucible. For example, referring to FIG. 9, the top portion 12 includes a center weir peg 48 that extends laterally across the center weir channel 34. The slip slurry flows around the center weir peg 48, thereby forming an opening 38 (FIG. 1) through the center weir 24 of the resulting crucible assembly 5. Alternatively or additionally, the top portion 12 includes an inner weir peg 55 that extends laterally across the inner weir channel 36 and forms an opening 41 (FIG. 1) in the inner weir 31. After the top portion 12 of the mold 8 is removed from the green body 40 and the bottom portion 18, the center weir peg 48 and the inner weir peg 55 may be removed (e.g., drilled or chiseled away). The locations of the pegs 48, 55 (and the resulting crucible openings 38, 41) are exemplary and other locations (e.g., height, relative circumferential position between the pegs, etc.) may be used. The mold 8 may include additional or other arrangements of pegs to form openings in the central dam 24 and / or the inner dam 31. In some embodiments, the mold 8 does not include pegs. For example, the openings between the dams may be formed directly in the green body and / or the resulting crucible (e.g., with a drill or chisel), and / or the crucible assembly 5 is configured so that silicon is poured over the dams.

[0029] Mold 8 is exemplary and other embodiments may include different arrangements of weirs, etc. (e.g., including only a single weir (i.e., only an inner weir) or two or more weirs) unless otherwise noted. In some embodiments, mold 8 may be reused for additional cycles to form crucible assembly 5 (e.g., used for 2, 3, 4, 5, or 10 or more cycles). Mold 8 may be dried between cycles, such as by placing the mold in a drying oven to evaporate liquid drawn therein during formation of green body 40.

[0030] Once the green body 40 is removed from the mold 8, the green body 40 may be sintered (e.g., in a drying oven) to dry and densify the green body 40 to form the unitized crucible assembly 5 (FIG. 1). The green body 40 may be sintered at a temperature of about 1200° C. to about 1800° C., about 1300° C. to about 1700° C., or about 1300° C. to about 1650° C. In some embodiments, the crucible assembly 5 has a moisture content of less than 20 wt%, less than 15 wt%, or less than 10 wt% after sintering.

[0031] The unitized crucible assembly 5 after sintering is shown in FIG. 1. In various embodiments of the present disclosure, the unitized crucible assembly 5 does not include seams (i.e., has no voids at these joints 13, 15) at the joints 13, 15 formed between the bottom 17 and the center dam 24 and the joints 15 formed between the bottom 17 and the inner dam 31. Alternatively or additionally, the unitized crucible assembly 5 does not include tucking at the joints 13, 15. Such tucking may be used to connect the dams 24, 31 at the crucible bottom 17 in a conventional crucible assembly. In the illustrated embodiment, the unitized crucible assembly 5 includes a single layer bottom 17 (i.e., the crucible assembly 5 does not include stacked crucibles, each with its own bottom). The unitized crucible assembly 5 may be transparent.

[0032] In some embodiments, the slip slurry is selected so that the resulting crucible assembly has a desired purity threshold. For example, and in some embodiments, the crucible assembly 5 includes calcium at a concentration of less than about 1 ppmw, less than about 0.8 ppmw, or less than about 0.7 ppmw. Alternatively or additionally, the crucible assembly 5 may include sodium at a concentration of less than about 0.5 ppmw, less than about 0.2 ppmw, or less than about 0.1 ppmw. Alternatively or additionally, the crucible assembly 5 may include potassium at a concentration of less than about 0.5 ppmw, less than about 0.2 ppmw, or less than about 0.1 ppmw. Alternatively or additionally, the crucible assembly 5 may include lithium at a concentration of less than about 0.5 ppmw, less than about 0.4 ppmw, or less than about 0.3 ppmw. Alternatively or additionally, crucible assembly 5 may include iron at a concentration of less than about 0.5 ppmw, less than about 0.3 ppmw, or less than about 0.15 ppmw.

[0033] In some embodiments, the mold 8 is selected (and / or treated) to achieve one or more of the purity amounts described above. For example, the mold may be made of porous silica (e.g., relative to a gypsum mold) to reduce the calcium content of the resulting crucible.

[0034] The unitized crucible assembly 5 shown and described herein is an exemplary assembly. The assembly 5 may have other dimensions (e.g., shallower or deeper melt in one or more melt zones), purities, features and / or configurations unless otherwise specified.

[0035] The disclosed methods for forming unitized crucibles may be used to produce single crystal silicon ingots. In such methods, unitized crucibles produced by embodiments of the disclosed methods are provided. In some embodiments, the unitized crucible assembly 5 includes a crucible melt zone 22 disposed between the outer sidewall 10 and a central dam 24. The unitized crucible assembly 5 also includes a stabilization zone 26 disposed between the central dam 24 and an inner dam 31. The unitized crucible assembly 5 also includes a growth zone 28 disposed within the inner dam 31.

[0036] Polycrystalline silicon is added to the crucible melt zone 22 where the silicon melts and replenishes the silicon melt. The silicon melt flows into the stabilization zone 26 through the central weir opening 38. The silicon melt then flows through the inner weir opening 41 into the growth zone 28 located within the inner weir 31. The silicon melt in the growth zone 28 contacts a single crystal seed crystal, which is pulled from the silicon melt to form a single crystal silicon ingot. The various silicon melt zones (e.g., melt zone 22, stabilization zone 26, and growth zone 28) allow for growth by a continuous Czochralski process in which polycrystalline silicon is added continuously or semi-continuously to the melt while ingots are continuously pulled from the growth zone 28.

[0037] Compared to conventional crucible assemblies for holding silicon melt, the disclosed crucible assembly and method of manufacturing such a crucible assembly have several advantages. By manufacturing a unitized (e.g., one-piece) crucible with a center dam and an inner dam, the crucible assembly allows for continuous ingot growth (continuous Czochralski) while allowing the advantages of a unitized crucible. By unitizing the crucible bottom, sidewalls, and dams, the crucible assembly is better able to hold tolerances (e.g., sidewall and dam height, wall thickness, melt channel, etc.). This allows the crucible assembly to be more easily installed into an ingot pulling system and reduces or eliminates the use of alignment tools (i.e., tools to fit together the various parts of a non-unitized crucible in an ingot pulling system). The unitized crucible is less rugged and can fit better into the susceptor of an ingot pulling apparatus. The unitized crucible also allows for control of wall thickness to improve thermal response, allows flexibility for doped chemistries, and reduces or eliminates prebond cycles (i.e., heating cycles used to connect the weirs to the crucible bottom) that consume run time for the ingot pulling assembly. The unitized crucible assembly also results in fewer processing and supply logistics compared to crucible assemblies formed from multiple pieces. In embodiments where the mold includes pegs that extend across the channels to form the weirs in the crucible, the resulting crucible has preformed openings that allow silicon melt to move to various melt zones within the resulting crucible during ingot growth.

[0038] In some embodiments, the slip and / or mold are selected such that the resulting crucible has a relatively low impurity content (e.g., less than about 1 ppmw calcium, less than about 0.5 ppmw sodium, less than about 0.5 ppmw potassium, less than 0.5 ppmw lithium, and / or less than 0.5 ppmw iron) to reduce the possibility of zero dislocation loss during ingot growth. In embodiments where the mold is made of porous silica, the crucible assembly may be of higher purity due to the lower calcium content of the porous silica compared to components cast from molds made of gypsum.

[0039] As used herein, the terms "about," "substantially," "essentially," and "approximately" when used in connection with a dimension, concentration, temperature, or other physical or chemical property or range of properties, are meant to cover variations that may exist at the upper and / or lower limits of the property or range of properties, including, for example, variations that result from rounding, measurement method, or other statistical variations.

[0040] When introducing elements of the disclosure or embodiments thereof, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the element. The terms "comprising," "including," "containing," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. The use of specific orientation terms (e.g., "top," "bottom," "side," etc.) is for convenience of description and does not require a particular orientation of the items being described.

[0041] Because various changes may be made in the structures and methods described above without departing from the scope of the present disclosure, it is intended that all matter contained in the above description and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense.

Claims

1. 1. A method of forming a unitized crucible assembly for holding a silicon melt for forming a silicon ingot by the Czochralski process, comprising: Providing a template, the template comprising: Bottom channel; an outer sidewall channel extending from the bottom channel; a central weir channel extending from the bottom channel; and having a channel network including: an inner dam channel extending from a bottom channel, the central dam channel being disposed between the outer sidewall channel and the inner dam channel; introducing a slip slurry into the channel network to fill the bottom channel, the outer sidewall channel, the central weir channel, and the inner weir channel with the slip slurry, the slip slurry comprising silica and a liquid carrier; removing at least a portion of the liquid carrier from the channel network to form a green body; Separating the green body from the crucible mold; and sintering the green body to dry and densify it to form a unitized crucible assembly.

2. 10. The method of claim 1, wherein the mold comprises a porous body and the liquid carrier is drawn into the mold by capillary action.

3. The method according to claim 2 , wherein the porous body comprises porous silica.

4. 4. The method of any one of claims 1 to 3, wherein the moisture content of the green body is less than about 50%, less than about 45%, at least about 30 wt%, at least about 35 wt%, at least about 40 wt%, at least about 45 wt%, from about 30 wt% to about 50 wt%, or from about 35 wt% to about 45 wt%.

5. The method of any one of claims 1 to 4, wherein the green body is sintered at a temperature of from about 1200°C to about 1800°C, from about 1300°C to about 1700°C, or from about 1300°C to about 1650°C.

6. The method of any one of claims 1 to 5, wherein the bottom channel, the outer sidewall channel, the central weir channel, and the inner weir channel are each fluidly connected to each other.

7. The method of claim 6 , wherein the bottom channel is rounded.

8. The method of claim 7 , wherein the unitized crucible assembly includes a single layer bottom.

9. The method of any one of claims 1 to 8, wherein the unitized crucible assembly is transparent.

10. The unitized crucible assembly is bottom; an outer sidewall extending upwardly from the base; a central weir extending upwardly from the base; and 10. The method of any one of claims 1 to 9, including an inner dam extending upwardly from the bottom, the central dam being disposed between the outer sidewall and the inner dam.

11. 11. The method of any one of claims 1 to 10, wherein the slip slurry and / or mold are selected to form a unitized crucible assembly having a calcium concentration of less than about 1 ppmw, a sodium concentration of less than about 0.5 ppmw, a potassium concentration of less than about 0.5 ppmw, a lithium concentration of less than about 0.5 ppmw, and an iron concentration of less than about 0.5 ppmw.

12. The mold is a center weir peg extending through the center weir channel and forming an opening in the center weir of the unitized crucible assembly to allow silicon melt to pass through the center weir; and an inner dam peg extending through the inner dam channel and forming an opening in the inner dam of the unitized crucible assembly to allow silicon melt to pass through the inner dam; 12. The method of claim 11, comprising:

13. 1. A method for growing a single crystal silicon ingot, comprising: Providing a unitized crucible assembly according to the method of claim 12; adding polycrystalline silicon to a crucible melt zone disposed between an outer sidewall and a central weir to form a silicon melt, the silicon melt flowing through an opening in the central weir to a stabilization zone disposed between the central weir and an inner weir, and the silicon melt flowing through an opening in the inner weir to a growth zone disposed within the inner weir; contacting the silicon melt in the growth zone with the seed crystal; pulling a seed crystal from the silicon melt to form a single crystal silicon ingot.

14. bottom; an outer sidewall extending upwardly from the base; a central weir extending upwardly from the base; and 13. A unitized crucible assembly formed by the method of any one of claims 1 to 12 including: an inner dam extending upwardly from the bottom, the central dam being disposed between the outer sidewall and the inner dam.

15. 1. A method of forming a unitized crucible assembly for holding a silicon melt for forming a silicon ingot by the Czochralski process, comprising: Providing a mold comprising a porous body and a channel network disposed within the porous body, the channel network comprising: Bottom channel; an outer sidewall channel extending from the bottom channel; and an inner weir channel extending from the bottom channel and positioned inwardly of the outer sidewall channel; a process comprising: introducing a slip slurry into the channel network to fill the bottom channels, the outer sidewall channels, and the inner weir channels with the slip slurry, the slip slurry comprising silica and a liquid carrier; drawing at least a portion of the liquid carrier into the mold by capillary action to form a green body; Separating the green body from the crucible mold; and firing the green body and drying and densifying the green body to form a unitized crucible assembly; The method includes:

16. 16. The method of claim 15, wherein the mold comprises a porous body and the liquid carrier is drawn into the mold by capillary action.

17. The method of claim 16 , wherein the porous body is formed from porous silica.

18. 18. The method of any one of claims 15 to 17, wherein the moisture content of the green body is less than about 50%, less than about 45%, at least about 30 wt%, at least about 35 wt%, at least about 40 wt%, at least about 45 wt%, from about 30 wt% to about 50 wt%, or from about 35 wt% to about 45 wt%.

19. The method of any one of claims 15 to 18, wherein the green body is sintered at a temperature of from about 1200°C to about 1800°C, from about 1300°C to about 1700°C, or from about 1300°C to about 1650°C.

20. The method of any one of claims 15 to 19, wherein the bottom channel, the outer sidewall channel, and the inner weir channel are each fluidly connected to each other.

21. The method of claim 20, wherein the bottom channel is rounded.

22. 22. The method of claim 21, wherein the unitized crucible assembly includes a single layer bottom.

23. The method of any one of claims 15 to 22, wherein the unitized crucible assembly is transparent.

24. The unitized crucible assembly is bottom; an outer sidewall extending upwardly from the base; and an inner dam extending upwardly from the bottom, the inner dam being positioned radially inward of the outer sidewall channel; The method according to any one of claims 15 to 23, comprising:

25. 25. The method of any one of claims 15 to 24, wherein the mold includes an inner dam peg extending through the inner dam channel and forming an opening in the inner dam of the unitized crucible assembly to allow the silicon melt to pass through the inner dam.

26. 26. The method of any one of claims 15 to 25, wherein the slip slurry and / or mold are selected to form a unitized crucible assembly having a calcium concentration of less than about 1 ppmw, a sodium concentration of less than about 0.5 ppmw, a potassium concentration of less than about 0.5 ppmw, a lithium concentration of less than about 0.5 ppmw, and an iron concentration of less than about 0.5 ppmw.

27. A lower portion; and an upper portion disposed over the lower portion, A central dam; and Inner weir channel, a top portion forming a crucible mold comprising: The upper and lower portions together a bottom channel; and A crucible mold forming a sidewall channel fluidly connected to the bottom channel, with a central weir channel and an inner weir channel extending from the bottom channel.

28. 30. The crucible mold of claim 27, wherein the upper portion includes a flange, the flange resting on the lower portion.

29. 29. The crucible mold of claim 27 or 28, wherein the crucible mold is porous.

30. 30. The crucible mold of claim 29, wherein the crucible mold is formed from porous silica.

31. 31. The crucible mold of any one of claims 27 to 30, including a center weir peg extending laterally across the center weir channel and forming an opening in the center weir of a crucible formed from the mold.

32. 32. The crucible mold of claim 31 including an inner dam peg extending laterally across the inner dam channel and forming an inner dam opening of a crucible formed from the mold.

33. The crucible mold of any one of claims 27 to 32, wherein the bottom channel is rounded.

34. The crucible mould of any one of claims 27 to 33, wherein the upper portion has a body having a lower surface and the lower portion has a body having an upper surface, the lower surface and the upper surface forming a bottom channel and a sidewall channel.

35. 35. The crucible mold of claim 34, wherein the top portion includes a flange extending from the body of the top portion, the flange resting on the body of the bottom portion.

36. 36. The crucible mold of claim 34 or 35, wherein at least a portion of the lower surface is rounded and at least a portion of the upper surface is rounded.

37. bottom; an outer sidewall extending upwardly from the base; a central weir extending upwardly from the base; and an inner dam extending upwardly from the bottom; The central weir is disposed between the outer sidewall and the inner weir; The bottom, outer sidewall, center dam, and inner dam are unitized, resulting in a crucible assembly with no seams at (1) the junction between the outer sidewall and the bottom, (2) the junction between the center dam and the bottom, and (3) the junction between the inner dam and the bottom.

38. 38. The crucible assembly of claim 37, wherein the bottom is rounded.

39. 39. The crucible assembly of claim 37 or 38, wherein the crucible assembly consists essentially of quartz.

40. 40. The crucible assembly of any one of claims 37 to 39, wherein the crucible assembly has a calcium concentration of less than about 1 ppmw, a sodium concentration of less than about 0.5 ppmw, a potassium concentration of less than about 0.5 ppmw, a lithium concentration of less than about 0.5 ppmw, and an iron concentration of less than about 0.5 ppmw.

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