Ingot pulling apparatus having a reflector assembly suspended from a support shaft

Abstract

An ingot pulling apparatus is disclosed having a reflector assembly suspended on support shafts, each of which may be connected to a joist, the joist being connected to a flange of the reflector assembly by two flexible joints spaced apart along the longitudinal axis of the joist.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 426977, filed November 21, 2022, which is incorporated herein by reference in its entirety.

[0002] The field of the disclosure relates to ingot pulling apparatus having a reflector assembly suspended from a support shaft extending above the reflector assembly. [Background technology]

[0003] Single crystal silicon ingots may be grown by the so-called Czochralski process, in which a silicon seed crystal is contacted with a silicon melt. The silicon seed crystal is withdrawn from the melt, thereby forming a seed-suspended silicon single crystal ingot. The silicon seed crystal is secured to a seed chuck that is connected to a pulling cable. The pulling cable supports the chuck and the seed crystal (and the ingot during crystal growth). The pulling cable is connected to a pulling mechanism that lowers and raises the pulling cable within the ingot pulling system.

[0004] As a monocrystalline silicon ingot is withdrawn from the melt, it may pass through a reflector assembly that directs heat back toward the ingot. Traditionally, the reflector assembly is supported by a series of vertically stacked graphite pieces in the hot zone. During melting of the solid polycrystalline silicon, the graphite pieces thermally expand, resulting in an unpredictable axial position of the reflector assembly.

[0005] A need exists for an ingot puller in which reflector assemblies are predictably and repeatedly positioned within the ingot puller while maintaining the integrity and lifespan of the components used to support the reflector assemblies.

[0006] 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

[0007] One aspect of the present disclosure is directed to an ingot pulling apparatus for producing single crystal silicon ingots. The ingot pulling apparatus includes a crucible assembly for holding a silicon melt. A crystal pulling housing defines a growth chamber for pulling a silicon ingot from the silicon melt. The crucible assembly is disposed within the growth chamber. A reflector assembly has an opening for receiving a single crystal silicon ingot as the ingot is pulled through the reflector assembly. The reflector assembly includes an upper flange and a shield extending downwardly from the upper flange. The ingot pulling apparatus includes two or more support shafts for supporting the reflector assembly. The support shafts extend upwardly from the reflector assembly. The ingot pulling apparatus includes two or more joists. Each joist is connected to the support shaft toward a lower end of the support shaft. Each joist is connected to the flange by first and second joints spaced apart from each other along a longitudinal axis of the joist.

[0008] Another aspect of the present disclosure is directed to an ingot pulling apparatus for producing single crystal silicon ingots. The ingot pulling apparatus includes a crucible assembly for holding a silicon melt. A crystal pulling housing defines a growth chamber for pulling a silicon ingot from the silicon melt. The crucible assembly is disposed within the growth chamber. The ingot pulling apparatus includes a reflector assembly having an opening for receiving the single crystal silicon ingot as the ingot is pulled through the reflector assembly. The reflector assembly includes an upper flange and a shield extending downwardly from the upper flange. The ingot pulling apparatus includes first and second support shafts for supporting the reflector assembly. The first and second support shafts extend upwardly from the reflector assembly. The ingot pulling apparatus does not include more than two support shafts. Each support shaft is connected to the crystal pulling housing at a support shaft port.

[0009] Yet another aspect of the present disclosure is directed to an ingot pulling apparatus for producing single crystal silicon ingots. The ingot pulling apparatus includes a crucible assembly for holding a silicon melt. A crystal pulling housing defines a growth chamber for pulling a silicon ingot from the silicon melt. The crucible assembly is disposed within the growth chamber. A reflector assembly has an opening for receiving the single crystal silicon ingot as the ingot is pulled through the reflector assembly. The reflector assembly includes an upper flange and a shield extending downward from the upper flange. The ingot pulling apparatus includes first and second support shafts for supporting the reflector assembly. The first and second support shafts extend upward from the reflector assembly. Each support shaft is connected to the upper flange by a flexible joint.

[0010] Various refinements exist to the features described in connection with the above-described aspects of the present disclosure. Additional features may be incorporated into the above-described aspects of the present disclosure. These refinements and additional features may exist individually or in any combination. For example, the various features described below in connection with any of the illustrated embodiments of the present disclosure may be incorporated, alone or in any combination, into any of the above-described aspects of the present disclosure. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view of an ingot pulling apparatus during ingot growth. [Figure 2] FIG. 2 is a schematic diagram of an ingot pulling apparatus having an upper segment and a lower segment removably connected to the upper segment. [Figure 3] FIG. 3 is a perspective view of a reflector assembly of an ingot pulling apparatus. [Figure 4] FIG. 4 is a perspective view of the support shaft and joist of the ingot pulling apparatus, showing two joints for connecting the joist to the reflector assembly. [Figure 5] FIG. 5 is an exploded perspective view of first and second casings, pins, and shells for connecting the support shaft to the joist. [Figure 6] FIG. 6 is a cross-sectional front view of a joint for connecting a joist to a reflector assembly. [Figure 7] FIG. 7 is a front view of the support shaft and joist connected to the flange of the reflector assembly. [Figure 8] FIG. 8 is a cross-sectional view of the outer gas shield and flange of the reflector assembly.

[0012] Corresponding reference characters indicate corresponding parts throughout the drawings. DETAILED DESCRIPTION OF THE INVENTION

[0013] Provisions of the present disclosure relate to an ingot pulling apparatus having a reflector assembly suspended from (i.e., hanging from) a support shaft extending upward from the reflector assembly. An example of an ingot pulling apparatus (or simply "ingot puller") is generally designated "100" in FIG. 1. The ingot pulling apparatus 100 includes a crucible assembly 102 for holding a melt 104 of semiconductor or solar-grade silicon material. The crucible assembly 102 is supported by a susceptor 106.

[0014] The ingot pulling apparatus 100 includes a crystal pulling housing 108 that defines a growth chamber 152 for pulling a silicon ingot from a silicon melt 104 along a pulling axis A. Referring now to FIG. 2 , the growth chamber 152 includes two portions: a lower growth chamber 155 (or simply the “lower chamber”) and an upper growth chamber 165 (or simply the “upper chamber”) disposed above the lower growth chamber 155. The hot zone (e.g., crucible, reflector assembly, susceptor, heater, etc.) of the ingot pulling apparatus 100 is disposed within the lower chamber 155. During ingot growth, the ingot 113 is pulled through the lower chamber 155 and continues to be pulled through the upper chamber 165 as the ingot lengthens.

[0015] Crystal puller housing 108 includes a domed lower segment 119 that defines a lower chamber 155 and an upper segment 140 that defines an upper chamber 165. The domed lower segment 119 includes a domed portion 169 that tapers to the diameter of the upper segment 140. The upper segment 140 is generally cylindrical and includes a lower end 159 and an upper end 163. The upper segment 140 of crystal pulling housing 108 is removably connected to the lower segment 119 (e.g., by fasteners, a gasket, etc.).

[0016] Crucible assembly 102 (FIG. 1) is disposed within lower chamber 155. Crucible assembly 102 has sidewalls 131 and a floor 129 and rests on susceptor 106. Susceptor 106 is supported by shaft 105. Susceptor 106, crucible assembly 102, shaft 105, and ingot 113 share a common longitudinal axis or "pull axis" A.

[0017] Within ingot pulling apparatus 100 is a pulling mechanism 114 for growing and pulling ingot 113 from melt 104. Pulling mechanism 114 includes a pulling cable 118, a seed holder or chuck 120 coupled to one end of pulling cable 118, and a seed crystal 122 coupled to chuck 120 for initiating crystal growth. One end of pulling cable 118 is connected to a pulley (not shown) or drum (not shown) of pulling mechanism 114, and the other end is connected to chuck 120, which holds seed crystal 122. Pulling mechanism 114 includes a motor for rotating the pulley or drum.

[0018] In operation, the seed crystal 122 is lowered so that it contacts the surface 111 of the melt 104. The pulling mechanism 114 is operated to raise the seed crystal 122. This causes a single crystal ingot 113 to be pulled from the melt 104.

[0019] During heating and crystal pulling, a crucible drive 107 (e.g., a motor) rotates the crucible assembly 102 and susceptor 106. A lifting mechanism 112 raises and lowers the crucible assembly 102 along the pulling axis A during the growth process. For example, the crucible assembly 102 may be in its lowest position (near the bottom heater 126) where a charge of solid-phase silicon 133 pre-added to the crucible assembly 102 is melted. Crystal growth begins by contacting the melt 104 with the seed crystal 122 and raising the seed crystal 122 with the pulling mechanism 114.

[0020] The crystal drive unit (not shown) may also rotate the pull cable 118 and ingot 113 in a direction opposite (e.g., counter-rotation) from the direction in which the crucible drive unit 107 rotates the crucible assembly 102. In embodiments using iso-rotation, the crystal drive unit may rotate the pull cable 118 in the same direction as the crucible drive unit rotates the crucible assembly 102.

[0021] The ingot puller 100 includes bottom insulation 110 and side insulation 124 to retain heat within the puller 100. In the illustrated embodiment, the ingot puller 100 includes a bottom heater 126 positioned below a crucible floor 129. The crucible assembly 102 may be moved relatively close to the bottom heater 126 to melt solid silicon charged into the crucible assembly 102.

[0022] According to the Czochralski single crystal growth process, a quantity of solid-phase silicon, such as polycrystalline silicon (i.e., "polysilicon"), is initially loaded into the crucible assembly 102. The semiconductor- or solar-grade solid silicon introduced into the crucible assembly 102 is melted by heat provided by one or more heating elements. Once the melt 104 is fully formed, the seed crystal 122 is lowered into contact with the surface 111 of the melt 104. The pulling mechanism 114 is activated to pull the seed crystal 122 from the melt 104. The resulting ingot 113 includes a crown portion 142 where the ingot tapers as it transitions outward from the seed crystal 122 to reach a target diameter. The ingot 113 includes a constant diameter portion 145, i.e., a cylindrical "crystal body" of the crystal, which is grown by increasing the pulling rate. The body 145 of the ingot 113 has a relatively constant diameter. The ingot 113 includes a tail or end cone (not shown) where the diameter of the ingot tapers after the body 145. Once the diameter is small enough, the ingot 113 is separated from the melt 104.

[0023] The crystal growth process may be a batch process in which solid silicon is initially added to the crucible 102 to form a silicon melt, and no additional solid silicon is added to the crucible 102 during crystal growth. In other embodiments, the crystal growth process is a continuous Czochralski process in which silicon is added to the crucible assembly during ingot growth.

[0024] The ingot pulling apparatus 100 includes a side heater 135 and a susceptor 106 surrounding the crucible assembly 102 to maintain the temperature of the melt 104 during crystal growth. The side heater 135 is positioned radially outward relative to the crucible sidewall 131 as the crucible assembly 102 moves up and down the pulling axis A. The side heater 135 and the bottom heater 126 may be any type of heater that enables the side heater 135 and the bottom heater 126 to operate as described herein. In some embodiments, the heaters 135 and 126 are resistive heaters. The side heater 135 and the bottom heater 126 may be controlled by a control system (not shown) so that the temperature of the melt 104 is controlled throughout the pulling process.

[0025] The ingot pulling apparatus 100 may include a reflector assembly 151. The reflector assembly 151 includes an opening 157 through which the single crystal silicon ingot 113 is pulled during ingot growth. The ingot pulling apparatus 100 may include an inert gas system that introduces and withdraws an inert gas, such as argon, into and from the growth chamber 152.

[0026] The ingot pulling apparatus 100 shown is an example, and unless otherwise specified, any ingot pulling apparatus 100 that includes a reflector assembly 151 may be used.

[0027] One embodiment of a reflector assembly 251 is shown in Figures 3-8. The reflector assembly 251 includes an upper flange 260 (or simply "flange") and a shield 264 extending downwardly from the upper flange 260. The reflector assembly 251 includes an opening 257 through which the single crystal silicon ingot is pulled. The reflector assembly 251 may include various components (including various plates and bands) that together form the flange and / or the shield (e.g., the flange may be made of various support plates that support various thermally insulating components). The shield 264 may include insulation and an outer cap to reduce or eliminate particle shedding from the shield 264 into the melt.

[0028] The ingot pulling apparatus 100 includes two or more support shafts 266, 269 (e.g., first and second support shafts 266, 269) extending upward from and supporting the reflector assembly 251. While the illustrated embodiment includes two support shafts 266, 269, other embodiments may use more than two support shafts (e.g., three, four, five, or more support shafts). In other embodiments, such as the illustrated embodiment, the ingot pulling apparatus includes only two support shafts 266, 269. In some embodiments, the reflector assembly 251 is not supported by any structure other than the support shafts during ingot growth (e.g., in embodiments having only two support shafts or in embodiments having more than two support shafts). In other embodiments, the reflector is supported by multiple shafts during installation and removal and is lowered onto a conventional graphite support before crystal growth begins.

[0029] The support shafts 266, 269 extend through the crystal pulling housing 108 at support shaft ports 271, 273. A translation mechanism (not shown), such as a bellows and ball screw, may be used to move the support shafts 266, 269 and adjust the position of the reflector assembly 251 up or down relative to the pulling axis A (FIG. 1) (e.g., during hot zone installation or removal). The support shafts 266, 269 may be cooled (e.g., water-cooled) by passing a fluid downward through the inlet 285 and rod and returning the fluid upward through the shaft and outlet 289. The shafts 266, 269 may include internal pipes and / or baffles for circulating the fluid. In other embodiments, the shafts 266, 269 are solid rods. In still other embodiments, the shafts 266, 269 are wires or cables. Shafts 266, 269 may be made of any material suitable for the ingot pulling equipment environment, and in some embodiments are made of stainless steel or carbon fiber composite (CFC).

[0030] The ingot pulling apparatus includes two or more joists 275, 277 (e.g., one for each support shaft). Each joist 275, 277 has a longitudinal axis X (FIG. 4). Each joist 275, 277 is connected to a corresponding support shaft 266, 269 toward a lower end 280 (FIG. 5) of the support shaft 266, 269. Referring to FIG. 5, the support shafts 266, 269 may be coupled to the joists 275, 277 by fasteners 283. The illustrated fastener 283 includes two casings 287, 288, which together form an internal cavity having a shape matching the shape of the support shafts 266, 269 toward the lower end 280. The support shafts 266, 269 may include recesses 290 and rims 291 to facilitate capture by the casings 287, 288. The casings 287, 288 may be connected to the joists 275, 277 by one or more pins 293. The casings 287, 288 and pins 293 may be held in place by a shell 295. In some embodiments, the joists 275, 277 are connected to the support shafts 266, 269 by clamps (not shown) or are welded to the support shafts 266, 269. In still other embodiments, the respective joists 275, 277 and support shafts 266, 269 are unitary (e.g., formed or molded together).

[0031] Returning to FIG. 4 , each joist 275, 277 is connected to the flange 260 ( FIG. 3 ) of the reflector assembly 251 by first and second joints 301, 303. The joints 301, 303 are spaced apart from one another along the longitudinal axis X of the joists 275, 277. In the illustrated embodiment, two joints 301, 303 are shown connecting each joist 275, 277 to the flange 260 ( FIG. 3 ); however, in other embodiments, more than two joints may be used. The first and second joints 301, 303 are flexible joints to accommodate thermal expansion of the reflector assembly 251 during heating (and contraction during cooling). Any suitable joint that allows radial movement of the reflector assembly 251 may be used. In the illustrated embodiment, each joint 301, 303 comprises two ball-and-socket joints. In other embodiments, a single ball-and-socket joint can be used. In other embodiments, a joint (e.g., upper or lower) comprises a wire or cable. In yet other embodiments, the joint includes a cylinder or cam body (e.g., instead of a ball). The joint may include two connections, the upper connection being a flexible joint and the lower connection including a pin that passes through a shaft, clamp, or collet.

[0032] The two joints 301, 303 may be identical, and exemplary joints 301, 303 are shown in FIG. 6. Each joint 301, 303 includes a stud 310 and first and second ball members 313, 316 extending from opposite ends of the stud 310. The first ball member 313 is disposed within a first socket 320. A first socket housing 325 defines the first socket 320. The first socket housing 325 is secured to a linkage 329 (FIG. 4) connected to the joists 275, 277 by a pin 327. The second ball member 316 is disposed within a second socket 323. A second socket housing 331 defines the second socket 323.

[0033] As shown in FIG. 7, the second socket housing 331 of each joint 301, 303 extends through the flange 260 of the reflector assembly 251. A rod 365 (FIG. 6) extends from the second socket housing 331. Each rod 365 is received in a support band 368 disposed below the flange 260. The support band 368 rests on a ledge 366 (FIG. 6) of each rod 365. The support band 368 may be disposed in a groove (not shown) formed in the bottom surface of the flange 260. The two support bands 368 support the weight of the reflector assembly 251.

[0034] Joints 301, 303 and their components may be made of any material that enables the joints to operate as described herein, such as molybdenum or CFC. Casings 287, 288, shell 295, and support band 368 may also be made of molybdenum or CFC.

[0035] In some embodiments, each support band 368 does not span two support rods 364. For example, each support band 368 may be a washer member (or other shape). In addition to or as an alternative to support bands, the suspension assembly may include a ball that fits into a socket notch in the flange 260 (but does not break through the flange 260), or a threaded connection (e.g., a threaded shaft connection where the shaft passes through the flange and is weight-supported by a nut) is used.

[0036] In some embodiments, the ingot pulling apparatus does not include a clamp for supporting the reflector assembly.

[0037] Referring now to FIG. 8 , the ingot pulling apparatus 100 includes an outer gas shield 375 that contacts the flange 260 and is radially outward of the flange 260. The outer gas shield 375 abuts the outer peripheral edge 362 of the flange 260. The outer gas shield 375 includes legs 369 extending from a body 378 of the outer gas shield 375. The legs 369 are positioned on an upper surface 371 of the flange 260. When the reflector assembly 251 is in a raised position relative to the pulling axis A, the legs 369 rest on the upper surface 371 of the flange 260. When the reflector assembly 251 is lowered, the outer gas shield body 378 contacts a ledge 380 of the ingot pulling apparatus 100, as shown in FIG. 8 . In this position, the outer gas shield 375 prevents process gas from migrating further into the ingot pulling apparatus 100. The reflector assembly 251 may continue to be lowered, causing the flange 260 to move downward relative to the outer gas shield 375, which is prevented from lowering by the ledge 380. The reflector assembly 251 may be lowered until the bottom surface 382 of the flange 260 contacts the ledge 380. In this arrangement, there is a region R over which the bottom surface 382 of the flange 260 may move, while the outer gas shield 375 continues to act as a seal to prevent process gases from migrating through the ingot pulling apparatus 100 (e.g., components below the reflector assembly 251).

[0038] The outer gas shield 375 and portions of the flange 260 (e.g., portions that support insulating components) may be made of any suitable material, such as graphite, that enables them to function as described herein. The reflector assembly 251 should be distinguished from other hot zone components, such as a cooling jacket, in which a cooling fluid is circulated throughout the jacket to cool the ingot.

[0039] The reflector assembly 251 may be removed from the ingot pulling apparatus 100 (eg, for cleaning) in a number of ways. For example, the reflector assembly 251 may be removed from the ingot pulling apparatus 100 by (1) disconnecting the linkages 329 from each of the joists 275, 277, respectively; (2) disconnecting the support shafts 266, 269 from each of the joists 275, 277, respectively; (3) lowering the support shafts 266, 269 while supporting the reflector assembly 251 from the bottom, allowing the ball member 313 to rise above the first socket housing 325, allowing the two halves of the first socket housing 325 to separate from each other and allowing the ball member 313 to pass through the linkage 329 as it is lowered; or (4) supporting the reflector assembly 251, removing the load from the lower band 368, sliding the band 368 and raising the support shafts 266, 269 away from the reflector assembly 251.

[0040] The ingot puller of the present disclosure offers several advantages over conventional ingot pullers. By suspending the reflector assembly, components of the ingot puller below the reflector assembly (e.g., stacked graphite components below the reflector assembly) do not affect the reflector assembly's vertical position during thermal expansion, making the reflector assembly's position more predictable and repeatable. The use of flexible joints (e.g., ball-and-socket joints) in the connection between the support shaft and the reflector assembly accommodates the radial and axial expansion of the reflector assembly, thereby improving the structural integrity and lifespan of the reflector assembly and support shaft. The flexible joints allow the reflector assembly to maintain a constant center position, reducing or eliminating reflector assembly "wobble." Embodiments using rigid support tubes or rods also reduce reflector assembly wobble.

[0041] In embodiments where the ingot pulling apparatus includes only two support shafts extending through the ingot pulling housing, the ingot pulling housing may include only two ports, simplifying the design of the ingot pulling apparatus. In embodiments where the support shafts are water-cooled, thermal expansion of the support shafts is reduced, maintaining the axial position of the reflector assembly. The reflector assembly can also be relatively easily removed from the ingot pulling apparatus (e.g., for cleaning).

[0042] As used herein, the terms "about," "substantially," "essentially," and "approximately," when used in conjunction with a range of dimensions, densities, temperatures, or other physical or chemical properties or characteristics, are meant to encompass variations that may exist at the upper and / or lower limits of the range of the property or characteristic, including variations that result, for example, from rounding, measurement methods, or other statistical variations.

[0043] When introducing elements of the present disclosure or embodiment(s) thereof, the articles "a," "an," "the," and "said" are intended to mean that there are one or more elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that additional elements may be present 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 mandate any particular orientation of the articles being described.

[0044] Because various changes may be made in the above-described structures and methods 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. An ingot pulling apparatus for producing a single crystal silicon ingot, comprising: The ingot pulling device is a crucible assembly for holding a silicon melt; a crystal pulling housing defining a growth chamber for pulling a silicon ingot from the silicon melt, the crucible assembly being disposed within the growth chamber; a reflector assembly having an opening for receiving the single crystal silicon ingot as the ingot is pulled through the reflector assembly, the reflector assembly comprising an upper flange and a shield extending downwardly from the upper flange; two or more support shafts for supporting the reflector assembly, the support shafts extending upward from the reflector assembly; two or more joists, each joist connected to the support shaft toward a lower end of the support shaft, each joist connected to the flange by first and second joints spaced apart from one another along a longitudinal axis of the joist; An ingot pulling apparatus comprising:

2. 2. The ingot pulling apparatus of claim 1, wherein only two support shafts support said reflector assembly.

3. 3. The ingot pulling apparatus of claim 1 or 2, wherein the reflector assembly is not supported within the ingot pulling apparatus by any structure other than the support shaft during ingot growth.

4. 4. The ingot pulling apparatus of claim 1, wherein the first and second joints are each a flexible joint.

5. 5. The ingot pulling apparatus of claim 4, wherein each flexible joint is a ball and socket joint.

6. 6. The ingot pulling apparatus of claim 5, wherein each flexible joint comprises two ball and socket joints.

7. 7. The ingot pulling apparatus of claim 1, wherein the two or more support shafts are water-cooled, each support shaft including an inlet for adding water to the support shaft and an outlet for removing water from the support shaft.

8. 8. An ingot pulling apparatus according to claim 1, further comprising an outer gas shield, the outer gas shield abutting an outer peripheral edge of the flange.

9. 9. An ingot pulling apparatus as claimed in any one of claims 1 to 8, wherein each support shaft extends through the crystal pulling housing at a support shaft port.

10. 10. An ingot pulling apparatus as claimed in any one of claims 1 to 9, comprising a support band positioned below the flange for supporting the reflector assembly.

11. 11. The ingot pulling apparatus of claim 1, wherein the shield includes an insulator and an outer cap, the insulator being disposed within the outer cap.

12. An ingot pulling apparatus for producing a single crystal silicon ingot, comprising: The ingot pulling device is a crucible assembly for holding a silicon melt; a crystal pulling housing defining a growth chamber for pulling a silicon ingot from the silicon melt, the crucible assembly being disposed within the growth chamber; a reflector assembly having an opening for receiving the single crystal silicon ingot as the ingot is pulled through the reflector assembly, the reflector assembly comprising an upper flange and a shield extending downwardly from the upper flange; first and second support shafts for supporting the reflector assembly, the first and second support shafts extending upwardly from the reflector assembly, the ingot pulling apparatus including no more than two support shafts, each support shaft connected to the crystal pulling housing at a support shaft port; and An ingot pulling apparatus comprising:

13. 13. The ingot pulling apparatus of claim 12, wherein the reflector assembly is not supported within the ingot pulling apparatus by any structure other than the support shaft during ingot growth.

14. 14. An ingot pulling apparatus as claimed in claim 12 or 13, wherein the support shaft is connected to the upper flange by at least one flexible joint.

15. 15. The ingot pulling apparatus of claim 14, wherein the flexible joint is a ball and socket joint.

16. 16. An ingot pulling apparatus as claimed in any one of claims 12 to 15, comprising an outer gas shield, the upper flange comprising a support plate, the outer gas shield abutting an outer periphery of the support plate.

17. 17. The ingot pulling apparatus of claim 12, wherein the shield includes an insulator and an outer cap, the insulator disposed within the outer cap.

18. 18. An ingot pulling apparatus as claimed in any one of claims 12 to 17, wherein the first and second support shafts are water-cooled, each support shaft including an inlet for adding water to the support shaft and an outlet for removing water from the support shaft.

19. 19. An ingot pulling apparatus as claimed in any one of claims 12 to 18, comprising a support band positioned below the flange for supporting the reflector assembly.

20. An ingot pulling apparatus for producing a single crystal silicon ingot, comprising: The ingot pulling device is a crucible assembly for holding a silicon melt; a crystal pulling housing defining a growth chamber for pulling the silicon ingot from the silicon melt, the crucible assembly being disposed within the growth chamber; a reflector assembly having an opening for receiving the single crystal silicon ingot as the ingot is pulled through the reflector assembly, the reflector assembly comprising an upper flange and a shield extending downwardly from the upper flange; first and second support shafts for supporting the reflector assembly, the first and second support shafts extending upward from the reflector assembly, each support shaft connected to the upper flange by a flexible joint; and An ingot pulling apparatus comprising:

21. 21. The ingot pulling apparatus of claim 20, wherein the flexible joint is a ball and socket joint.

22. 22. The ingot pulling apparatus of claim 20 or claim 21, wherein the reflector assembly is not supported within the ingot pulling apparatus by any structure other than the support shaft during ingot growth.

23. 23. An ingot pulling apparatus as claimed in any one of claims 20 to 22, comprising an outer gas shield, the upper flange comprising a support plate, the outer gas shield abutting an outer periphery of the support plate.

24. 24. The ingot pulling apparatus of any one of claims 20 to 23, wherein the shield includes an insulator and an outer cap, the insulator disposed within the outer cap.

25. 25. An ingot pulling apparatus as claimed in any one of claims 20 to 24, wherein the first and second support shafts are water-cooled, each support shaft including an inlet for adding water to the support shaft and an outlet for removing water from the support shaft.

26. 26. An ingot pulling apparatus as claimed in any one of claims 20 to 25, comprising a support band positioned below the flange for supporting the reflector assembly.

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