Ingot pulling apparatus and method for growing single crystal silicon ingots with reduced lower chamber deposits

Abstract

An ingot pulling apparatus and method for growing single crystal silicon ingots with reduced lower chamber deposits is disclosed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 480,663, filed January 19, 2023, the contents of which are incorporated herein by reference in their entirety. [Technical Field]

[0002] The present disclosure relates to an ingot pulling apparatus and method for growing single crystal silicon ingots with reduced lower chamber deposits. [Background technology]

[0003] Single crystal silicon ingots can be grown by the so-called Czochralski method, in which a silicon seed crystal is contacted with a silicon melt and pulled out of the melt to form a single crystal silicon ingot suspended by the seed crystal.

[0004] In ingot pullers that grow multiple crystals per batch, the upper pulling chamber is separated from the lower chamber by an isolation valve. Traditionally, the upper chamber is isolated from the lower chamber to isolate the molten silicon in the lower growth chamber during (1) seed material replacement, (2) seed cable replacement, and (3) removed grown ingots.

[0005] Separation and reconnection of the two chambers can be achieved by properly controlling the pressures in the two chambers, maintained by suitable vacuum pumps and process gas supplies (e.g., argon). When the isolation valve is open, process gas from the main inlet at the top of the ingot puller flows downward in a strong laminar flow, since the gas direction is top to bottom. When the isolation valve is closed, a separate process gas inlet located below the isolation valve on the side of the growth chamber is used to introduce process gas. This causes the process gas to flow horizontally, or at a relatively large angle to the pulling axis of the ingot puller. This turbulence in the upper part of the lower chamber of the puller can contribute to particle deposition on the hot-zone components.

[0006] During ingot processing, silicon oxide evaporates from the free surface of the melt. The evaporation rate is affected by the process recipe used to achieve the desired oxygen content during crystal growth. Oxide evaporation affects the success of single crystal growth because evaporated oxide particles deposit on the cold walls within the puller and then fall to the melt surface during crystal growth. Volatile doping elements can also evaporate from the melt surface and deposit on the cold wall surfaces inside the ingot puller. The evaporation of volatile dopants promotes the evaporation of silicon oxide gas from the melt surface, increasing the deposition. Deposits that form within the ingot puller (e.g., cooling jacket) can flake off during ingot growth, potentially causing a loss of zero-dislocation growth in single crystal silicon ingots or introducing defects (e.g., slip and twin lamellae) within the ingot.

[0007] A need exists for an ingot pulling apparatus and method for growing single crystal silicon ingots that can reduce deposits formed during ingot processing.

[0008] This section is intended to introduce the reader to various aspects of art, which may be related to various aspects of the disclosure, which are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to better understand the various aspects of the present disclosure. As such, it should be read in this light, and not as admissions of prior art. Summary of the Invention

[0009] One aspect of the present disclosure relates to an ingot pulling apparatus for producing single crystal silicon ingots. The ingot pulling apparatus includes a crucible assembly for holding a silicon melt. An ingot 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 housing includes a lower segment and an upper segment. The lower segment defines the lower segment chamber. The crucible assembly is disposed within the lower segment chamber. The upper segment is disposed above the lower segment and defines the upper segment chamber. The apparatus includes a shut-off valve movable between an open position, in which the lower segment chamber is in fluid communication with the upper segment chamber, and a closed position, in which the lower segment chamber is isolated from the upper segment chamber. The apparatus includes a process gas supply assembly having an inlet extending through the ingot pulling apparatus housing for introducing process gas into the growth chamber. A nozzle is in fluid communication with the inlet for directing process gas into the lower segment chamber.

[0010] Another aspect of the present disclosure relates to an ingot pulling apparatus for producing single crystal silicon ingots. The apparatus includes a crucible assembly for holding a silicon melt. The ingot puller housing defines a growth chamber for pulling a single crystal silicon ingot from the silicon melt along a pulling axis. The crucible assembly is disposed within the growth chamber. The ingot puller housing includes a lower segment and an upper segment. The lower segment defines the lower segment chamber. The crucible assembly is disposed within the lower segment chamber. The upper segment is disposed above the lower segment and defines the upper segment chamber. The apparatus includes a shut-off valve movable between an open position, in which the lower segment chamber is in fluid communication with the upper segment chamber, and a closed position, in which the lower segment chamber is isolated from the upper segment chamber. The apparatus includes a process gas supply assembly. The process gas supply assembly has an inlet extending through the ingot puller housing for introducing process gas into the growth chamber. A shower plate is disposed below the shut-off valve. The shower plate is in fluid communication with the inlet. The shower plate includes a plurality of outlets for exhausting process gases into the lower segment chambers.

[0011] Yet another aspect relates to a method for forming a single crystal silicon ingot in an ingot puller. The ingot puller includes a crucible assembly for holding a silicon melt and an ingot puller housing defining a growth chamber for pulling a single crystal silicon ingot from the silicon melt. The crucible assembly is disposed within the growth chamber. The ingot puller housing includes a lower segment defining a lower segment chamber and an upper segment disposed above the lower segment defining an upper segment chamber. The crucible assembly is disposed within the lower segment chamber. The isolation valve is movable between an open position in which the lower segment chamber is in fluid communication with the upper segment chamber and a closed position in which the lower segment chamber is isolated from the upper segment chamber. Solid silicon feedstock is introduced into the crucible assembly. The crucible assembly containing the silicon feedstock is heated to form a silicon melt within the crucible assembly. A silicon seed crystal is brought into contact with the silicon melt. The silicon seed crystal is pulled along a pulling axis to grow a single crystal silicon ingot. The single crystal silicon ingot is separated from the melt. After separating the single crystal silicon ingot from the melt, the ingot is cooled while remaining entirely within the upper segment chamber. While the single crystal silicon ingot is cooling, the shut-off valve is in the open position. While the single crystal silicon ingot is cooling within the upper segment chamber, process gas is directed from the upper segment chamber to the lower segment chamber. The single crystal silicon ingot is pulled from the upper segment chamber. While the single crystal silicon ingot is being pulled, the shut-off valve is in the closed position.

[0012] Various refinements exist in the features of the above aspects of the present disclosure. Furthermore, additional features may be incorporated into the above aspects of the present disclosure. These refinements and additional features may exist alone or in any combination. For example, the various features discussed 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 aspects of the present disclosure. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view of an ingot pulling apparatus during ingot growth. [Figure 2] 1 is a schematic diagram of an ingot pulling apparatus having an upper segment and a lower segment. [Figure 3] FIG. 1 is a schematic diagram of an ingot pulling apparatus showing isolation valves and a process gas supply assembly. [Figure 4] 1 is a schematic diagram of an ingot pulling apparatus in which the process gas supply assembly includes a nozzle. [Figure 5] FIG. 2 is a schematic diagram of a nozzle. [Figure 6] 1 is a schematic diagram of an ingot pulling apparatus in which the process gas supply assembly includes a shower plate. [Figure 7] FIG. 7 is a schematic diagram showing the process gas flow in the ingot pulling apparatus of FIG. 6. [Figure 8] FIG. 5 is a schematic diagram showing the process gas flow in the ingot pulling apparatus of FIG. [Figure 9] 1 is a graph showing the normalized ratio of success rates of zero dislocation (ZD) growth between the conventional method ("Before") and the method of opening the isolation valve during cooling as described in Example 1 ("After");

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

[0015] Provisions of the present disclosure relate to an ingot puller that improves the flow of process gas in a lower segment of the ingot puller while an isolation valve is closed, and a method for producing a single crystal silicon ingot with improved process gas flow.

[0016] 1, an exemplary ingot puller (or simply "ingot puller") is generally designated "100." The ingot puller 100 includes a crucible assembly 102 for holding a melt 104 of silicon, a semiconductor or solar-grade material. The crucible assembly 102 is supported by a susceptor 106.

[0017] The ingot pulling apparatus 100 pulls a single crystal silicon ingot 113 from a silicon melt 104 along an axis A. 100 The ingot puller 100 includes an ingot puller housing 108 that defines a growth chamber 152 through which the ingot 113 is pulled along the ingot puller housing 108. Referring to FIG. 2, the growth chamber 152 includes two portions: a lower segment chamber 155 (also referred to simply as the "lower chamber") and an upper growth chamber 165 (also referred to simply as the "upper chamber") disposed above the lower segment chamber 155, which are separated by a shut-off valve 170 (or shut-off valve housing 172). The hot zone (e.g., crucible, reflector, susceptor, heater, etc.) of the ingot puller 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 elongates.

[0018] Ingot puller housing 108 includes a lower segment 119 that defines a lower chamber 155 and an upper segment 140 that defines an upper chamber 165. At least a portion of lower segment 119 has a larger diameter than upper segment 140. Lower segment 119 has a dome-shaped portion 169 that tapers in size toward the diameter of upper segment 140. Upper segment 140 is generally cylindrical and includes an upper end 163 and a lower end 159.

[0019] The crucible assembly 102 (FIG. 1) is disposed within the lower chamber 155. The crucible assembly 102 has sidewalls 131 and a bottom surface 129 and rests on a susceptor 106. The susceptor 106 is supported by a shaft 105. The susceptor 106, crucible assembly 102, shaft 105, and ingot 113 are aligned along a common longitudinal axis, or "pulling axis," A. 100 It has.

[0020] The ingot pulling apparatus 100 includes a pulling mechanism 114 for growing and pulling an ingot 113 from the melt 104. The pulling mechanism 114 includes a pulling cable 118, a seed crystal holder or chuck 120 connected to one end of the pulling cable 118, and a seed crystal 122 (connected to the chuck 120) for initiating crystal growth. One end of the pulling cable 118 is connected to a pulley (not shown) or drum (not shown) of the pulling mechanism 114, and the other end is connected to the chuck 120 that holds the seed crystal 122. The pulling mechanism 114 includes a motor that rotates the pulley or drum.

[0021] In operation, the seed crystal 122 is lowered until it contacts the surface 111 of the melt 104. The pulling mechanism 114 is activated to raise the seed crystal 122. This causes the single crystal ingot 113 to be pulled from the melt 104.

[0022] During heating and crystal pulling, a crucible drive unit 107 (e.g., a motor) rotates the crucible assembly 102 and the susceptor 106. A lift mechanism 112 lifts the crucible assembly 102 along a pulling axis A during the growth process. 100 For example, the crucible assembly 102 may be at its lowest position (near the bottom heater 126) melting a charge of solid phase silicon 133 that was previously added to the crucible assembly 102. Crystal growth is initiated by contacting the melt 104 with the seed crystal 122 and lifting the seed crystal 122 with the pulling mechanism 114.

[0023] The crystal drive unit (not shown) can also rotate the pulling cable 118 and ingot 113 in the opposite direction (e.g., counter-rotation) to the direction that the crucible drive unit 107 rotates the crucible assembly 102. In embodiments using uniform rotation, the crystal drive unit can rotate the pulling cable 118 in the same direction that the crucible drive unit rotates the crucible assembly 102.

[0024] The ingot pulling apparatus 100 includes bottom insulation 110 and side insulation 124 for retaining heat within the pulling apparatus 100. In the illustrated embodiment, the ingot pulling apparatus 100 includes a bottom heater 126 positioned below a crucible bottom surface 129. The crucible assembly 102 can be moved into relatively close proximity to the bottom heater 126 to melt solid silicon charged into the crucible assembly 102.

[0025] According to the Czochralski single crystal growth process, solid-phase silicon, such as polycrystalline silicon (“polysilicon”), is first 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, and the seed crystal 122 is pulled from the melt 104. The resulting ingot 113 includes a tapered crown portion 142 that transitions outward from the seed crystal 122 until the ingot reaches a target diameter. The ingot 113 includes a constant diameter portion 145, or cylindrical “body” of the crystal, that 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) that tapers to a reduced diameter behind the body 145. Once the diameter is sufficiently reduced, the ingot 113 is separated from the melt 104.

[0026] The crystal growth process may be a batch process, in which solid silicon is initially added to the crucible assembly 102 to form a silicon melt, without additional solid silicon being added to the crucible assembly 102 during crystal growth. In other embodiments, the crystal growth process is a continuous Czochralski process, in which a constant amount of silicon is added to the crucible assembly during ingot growth.

[0027] 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 such that the crucible assembly 102 is aligned with the pulling axis A. 100 The side heater 135 and the bottom heater 126 are positioned radially outward relative to the crucible sidewall 131 as they move up and down along the crucible wall 131. The side heater 135 and the bottom heater 126 can be any type of heater operable as described herein. In some embodiments, the heaters 135, 126 are resistive heaters. The side heater 135 and the bottom heater 126 are controlled by a control system (not shown) to control the temperature of the melt 104 throughout the pulling process.

[0028] The ingot pulling apparatus 100 may include a heat shield 151 that covers the ingot 113 and is positioned within the crucible assembly 102 during crystal growth. The ingot pulling apparatus 100 may also include an inert gas system for introducing and evacuating an inert gas, such as argon, from the growth chamber 152.

[0029] The ingot 102 is covered by a cooling jacket 132. The heat shield 151 and the cooling jacket 132 are each mounted in a lower chamber 155 above the melt 104. The heat shield 151 is positioned radially outward from the cooling jacket 132, and the ingot 113 is positioned along the pulling axis A. 100The pull axis A defines an elongated passage 134 sized and shaped to receive the ingot 113 as it is pulled from the melt 104 along the pull axis A. A heat shield 151 is positioned above the melt-gas interface 126, forming a gap 136 therebetween. A cooling jacket 132 is positioned radially inward from the heat shield 151 and disposed within the elongated passage 134. The cooling jacket 132 is positioned radially inward from the pull axis A. 100 The ingot 113 is arranged concentrically with the heat shield 151 along the pulling axis A by the pulling mechanism 114. 100 The passages 134, 140 define a central passage 144 for receiving the ingot 113 as it is pulled along the passages 134, 140. The heat shield 151 blocks and / or reflects radiant heat from the ingot 113 as it is pulled through the passage 134. The cooling jacket 132 may be in the form of a cylindrical, fluid-cooled heat exchanger that facilitates cooling the ingot 113 as it is pulled through the passage 144. The heat shield 151 and cooling jacket 132 facilitate controlling the axial and radial temperature gradients that cause the molten silicon to solidify and crystallize from the melt 104 into the growing ingot 113. The configuration of the heat shield 151 and cooling jacket 132 may be varied to enhance the temperature effects within the passages 134, 140 as the ingot 113 is pulled.

[0030] The illustrated ingot puller 100 is an exemplary ingot puller and, unless otherwise specified, other ingot pullers suitable for growing single crystal silicon ingots may be used.

[0031] 3, the ingot pulling apparatus 100 includes an isolation valve 170. The isolation valve 170 is movable between an open position, in which the lower segment chamber 155 (FIG. 2) is in fluid communication with the upper segment chamber 165, and a closed position, in which the lower segment chamber 155 is isolated from the upper segment chamber 165. In the illustrated embodiment, the isolation valve 170 is a plate sealed with an O-ring 171. The isolation valve 170 can be a "flipping" or "swing" type valve. The isolation valve 170 can be disposed within an isolation valve housing 172. In some embodiments, the isolation valve 170 is disposed in a smaller diameter cylindrical portion of the ingot pulling apparatus.

[0032] The ingot puller 100 includes a process gas supply assembly 174 for adding a process gas (e.g., an inert gas such as argon) to the lower segment chamber 155. The process gas supply assembly 174 includes a first inlet 176 extending through the ingot puller housing 108 for introducing the process gas into the growth chamber 152. The process gas flows from a process gas source 200 (FIG. 2) through the inlet 176 and downwardly toward a process gas outlet 177 (FIG. 1) located below the crucible assembly 102. The first inlet 176 is located below the isolation valve 170 (i.e., along the pulling axis A). 100 (lower than shut-off valve 170 relative to FIG. 1) so that process gases can circulate through lower chamber 155 even when valve 170 is closed.

[0033] 4, the process gas supply assembly 174 includes an annular process gas manifold 182. The manifold 182 includes a process gas plenum 178 therein. The plenum 178 is in fluid communication with the first inlet 176. The annular process gas manifold 182 includes one or more outlets 188 extending through an inner surface 191 of the manifold 182. The outlets 188 are in fluid communication with the process gas plenum 178. The manifold 182 is positioned along the pulling axis A of the ingot pulling apparatus 100. 100 1, it is located below the shutoff valve 170.

[0034] In the embodiment shown in FIG. 4, the process gas supply assembly 174 includes nozzles 179. The nozzles 179 are in fluid communication with the inlets 176 for directing process gas into the lower chamber 155 ( FIG. 2 ). The nozzles 179 are alignable with the outlets 188 of the manifold 182 and are in fluid communication with the process gas plenum 178 and the inlets 176. Each nozzle 179 has a nozzle inlet 195 ( FIG. 5 ) (aligned with the outlets 188) and a nozzle outlet 197. The size (i.e., cross-sectional area) of the nozzle inlets 195 is larger than the size of the nozzle outlets 197, which increases the velocity of the process gas as it exits the nozzles 179. The nozzles 179 redirect the flow of the process gas.

[0035] Each nozzle 179 is on the discharge axis A 179 Discharge axis A 179 indicates the pulling axis A of the ingot pulling apparatus 100 100 In some embodiments, the angle λ is 45° or less, and in other embodiments, 30° or less, 25° or less, or 10° or less. 179 is the pulling axis A of the ingot pulling device 100 is parallel to

[0036] The process gas supply assembly 174 can include one nozzle, or at least two, at least four, or at least ten nozzles in fluid communication with an inlet 176 for directing process gas into the lower segment chamber 155 (FIG. 2). When multiple nozzles 179 are used, the nozzles 179 are spaced (e.g., equally spaced) around the periphery of the manifold 182.

[0037] The ingot puller 100 also includes a second process gas inlet 199 (FIG. 2) that is used to introduce process gas into the upper segment chamber 165 (e.g., when the isolation valve 170 is open). The second inlet 199 extends into the ingot puller housing 108 and is in fluid communication with a process gas source 200 (e.g., argon).

[0038] Another embodiment of a process gas supply assembly 174 is shown in FIG. 6. The illustrated process gas supply assembly 174 can be used in the exemplary ingot puller 100 shown in FIGS. 1-2. The process gas supply assembly 174 includes an inlet 176 extending through the ingot puller housing 108 to introduce process gas into the growth chamber 152. The process gas supply assembly 174 also includes a shower plate 200 positioned below the shut-off valve 170 and in fluid communication with the inlet 176. The shower plate 200 includes a plurality of outlets 205 for exhausting process gas into the lower segment chamber 155 (FIG. 2). For example, the shower plate 200 may include at least five openings 205, at least 10 openings 205, at least 20 openings 205, or at least 25 openings 205. The isolation valve 170 may include a gas plenum within the isolation valve 170 that is in fluid communication with an inlet 176 of the process gas supply assembly 174 and a plurality of outlets 205 of the shower plate 200 .

[0039] Each outlet 205 of the shower plate is aligned along a vertical axis A 205 In the embodiment shown in FIG. 205 is the pulling axis A of the ingot pulling device 100 In other embodiments, the longitudinal axis A of each outlet 205 is parallel to 205 makes an angle with the pulling axis, which angle can be 45° or less, 30° or less, 25° or less, or 10° or less.

[0040] 6, the shower plate 200 is connected (eg, cast, welded, or fastened) to the shut-off valve 170. The shower plate 200 moves with the shut-off valve 170 between an open position and a closed position.

[0041] In some embodiments, the flow of process gases is controlled during ingot growth (i.e., during ingot cooling) to reduce deposit formation in the lower chamber 155. After ingot growth (i.e., after end-cone formation), the single crystal silicon ingot 113 (FIG. 1) is separated from the melt 104. The pulling mechanism 114 pulls the ingot 113 (e.g., the entire ingot) into the upper chamber 165 and above the isolation valve 170. The pulling mechanism 114 is stopped, and the single crystal silicon ingot is allowed to cool. During cooling, the isolation valve 170 is in the open position, and process gases flow through the second inlet 199 (FIG. 2), pass through the upper chamber 165, the isolation valve housing 172, and into the lower chamber 155 (without flowing via the first inlet 176). The cooled ingot 113 can be lifted from the upper segment 140 through the open cover for ingot removal with the isolation valve 170 in the closed position (and process gas passing through the first inlet 176 but not through the second inlet 199).

[0042] The ingot pulling apparatus 100 may include a first process gas valve 209 ( FIG. 2 ) for regulating the flow of process gas from the process gas source 200 and the first inlet 176. The first process gas valve 209 is movable between an open position, in which the first inlet 176 is in fluid communication with the process gas source 200, and a closed position, in which process gas is prevented from flowing from the process gas source 200 through the first inlet 176. The apparatus 100 may also include a second process gas valve 211 for regulating the flow of process gas from the process gas source 200 and the second inlet 199. The second process gas valve 211 is movable between an open position, in which the second inlet 199 is in fluid communication with the process gas source 200, and a closed position, in which process gas is prevented from flowing from the process gas source 200 through the second inlet 199. While the ingot is cooling in the upper chamber 165 (with the shut-off valve 170 open), the first process gas valve 209 is in a closed position and the second process gas valve 211 is in an open position. While the single crystal silicon ingot 113 is being pulled from the upper segment chamber 165 (with the shut-off valve closed), the first process gas valve 209 is in an open position and the second process gas valve 211 is in a closed position, which allows process gas to be introduced below the closed shut-off valve 170 and flow into the lower chamber 155.

[0043] The method of reducing the time that the isolation valve is closed (i.e., cooling the ingot with the valve open) can be combined with any of the ingot puller configurations (i.e., process gas supply assembly 174) described above.

[0044] The disclosed apparatus and method offer several advantages over conventional ingot pulling apparatuses and methods for forming single-crystalline silicon ingots. In embodiments where the ingot pulling apparatus includes a nozzle directing process gas downward from a first inlet, the process gas can flow more vertically and / or laminarly through the lower segment chamber when the shutoff valve is closed (FIG. 8). In embodiments where the ingot pulling apparatus includes a shower plate positioned below the shutoff valve, the process gas can flow more vertically and / or laminarly through the lower segment chamber when the shutoff valve is closed (FIG. 7). A more vertical and / or laminar flow of process gas reduces backflow of process gas and reduces the deposition of oxides and other particles in the lower chamber. This reduces the frequency of particles falling into the melt and causing zero dislocation loss. Turbulence in the lower chamber and gas vortices above the free surface of the melt can be reduced by using a more vertical process gas flow. This reduces gas evaporation from the melt onto the upper hot zone (e.g., the reflector and cooling jacket) and the upper walls of the lower chamber. In embodiments where the isolation valve is open during cool down, gas flows from the process gas inlet above the isolation valve for a longer period of time, reducing deposition and zero dislocation loss.

[0045] Example The processes herein are further illustrated by the following examples, which should not be construed as limiting.

[0046] Example 1: Effect of opening the isolation valve during ingot cooling on zero dislocation loss In an ingot pulling system similar to the exemplary system shown in Figures 1-2, after ingot formation, a single crystal silicon ingot was fully pulled into the upper segment chamber 165. The shutoff valve 170 was left open while the ingot cooled in the upper segment chamber. The second valve 211 remained open, while the first valve 209 was closed, allowing process gases to flow vertically through the upper chamber 165 and into the lower chamber 155. By keeping the valve 170 in the open position during cooldown, the open time of the valve 170 was extended by an additional 1-4 hours compared to the conventional process. This procedure was repeated for multiple ingots (over several months, in the puller) to evaluate the impact on the zero dislocation (ZD) success rate. As shown in Figure 9, shortening the shutoff valve closing time ("after") improved the ZD success rate. Opening the shutoff valve during cooldown reduced the deposition of oxides and volatile gases on the upper region of the lower segment chamber 155 and the cooling jacket. This maintained the cleanliness of the ingot pulling equipment and reduced zero dislocation losses due to particle dropping into the melt.

[0047] As used herein, the terms "about," "substantially," "essentially," and "approximately," when used in conjunction with ranges of dimensions, concentrations, temperatures, or other physical or chemical properties or characteristics, are intended to encompass variations that may exist at the upper and / or lower limits of the range of such properties or characteristics, including, for example, variations due to rounding error, measurement method, and other statistical variations.

[0048] When introducing elements of this disclosure or embodiments thereof, the articles "a," "an," "the," "said," etc. mean that there are one or more elements. The terms "comprising," "including," "containing," and "having" are inclusive and mean that there may be additional elements other than the listed elements. The use of specific orientational terms (e.g., "top," "bottom," "side," etc.) is for convenience of description and does not require a specific orientation of the described articles.

[0049] Because various changes may be made in the above-described structures and methods without departing from the scope of the disclosure, all matter contained in the above description and shown in the accompanying drawings is intended to be interpreted as illustrative and not in a limiting sense.

Claims

1. An ingot pulling apparatus for producing a single crystal silicon ingot, a crucible assembly for holding the silicon melt; an ingot pulling housing defining a growth chamber for pulling a single crystal silicon ingot from a silicon melt, the crucible assembly being disposed within the growth chamber; a lower segment defining a lower segment chamber, the crucible assembly being disposed within the lower segment chamber; and an upper segment disposed above the lower segment and defining an upper segment chamber; an ingot pulling housing including: an isolation valve movable between an open position in which the lower segment chamber is in fluid communication with the upper segment chamber and a closed position in which the lower segment chamber is isolated from the upper segment chamber; 1. A process gas supply assembly comprising: an inlet extending through the ingot puller housing for introducing process gases into the growth chamber; and a nozzle in fluid communication with the inlet for introducing a process gas into the lower segment chamber; a process gas supply assembly including: An ingot pulling apparatus comprising:

2. 2. The ingot pulling apparatus of claim 1, wherein the nozzle has a discharge axis, the discharge axis forming an angle with a pulling axis of the ingot pulling apparatus, the angle being 45 degrees or less, 30 degrees or less, 25 degrees or less, or 10 degrees or less.

3. 3. The ingot pulling apparatus of claim 2, wherein the nozzle has a discharge axis, the discharge axis being parallel to a pulling axis of the ingot pulling apparatus.

4. 4. The ingot pulling apparatus of claim 1, further comprising an annular process gas manifold, the manifold being positioned below the shut-off valve relative to a pulling axis of the ingot pulling apparatus, the manifold including a process gas plenum therein, the process gas plenum being in fluid communication with the nozzle.

5. 5. The ingot pulling apparatus of claim 4, wherein the annular process gas manifold includes one or more outlets extending through an inner surface of the manifold and in fluid communication with the process gas plenum, the nozzles being aligned with the outlets of the process gas manifold.

6. 5. The ingot pulling apparatus of claim 1, further comprising at least two, at least four, or at least ten nozzles in fluid communication with the inlet for directing process gas into the lower segment chamber.

7. 7. An ingot pulling apparatus according to claim 1, wherein the nozzle includes a nozzle inlet and a nozzle outlet, and the cross-sectional area of ​​the nozzle inlet is larger than the cross-sectional area of ​​the nozzle outlet.

8. 8. An ingot pulling apparatus according to any preceding claim, wherein the inlet is a first inlet and the ingot pulling apparatus includes a second inlet extending through the ingot pulling housing for introducing process gas into the upper segment chamber.

9. 9. An ingot pulling apparatus according to claim 1, wherein the lower segment includes a dome-shaped portion, and the upper segment is cylindrical, the diameter of the upper segment being smaller than the diameter of the lower segment.

10. An ingot pulling apparatus for producing a single crystal silicon ingot, a crucible assembly for holding the silicon melt; an ingot pulling housing defining a growth chamber for pulling a single crystal silicon ingot from a silicon melt along a pulling axis, the housing comprising: a lower segment defining a lower segment chamber, the crucible assembly being disposed within the lower segment chamber; and an upper segment disposed above the lower segment defining an upper segment chamber; an ingot pulling housing including: an isolation valve movable between an open position in which the lower segment chamber is in fluid communication with the upper segment chamber and a closed position in which the lower segment chamber is isolated from the upper segment chamber; 1. A process gas supply assembly comprising: an inlet extending through the ingot puller housing for introducing process gases into the growth chamber; and a process gas supply assembly including: a shower plate disposed below the isolation valve, the shower plate being in fluid communication with the inlet and including a plurality of outlets for discharging process gas into the lower segment chamber; An ingot pulling apparatus comprising:

11. 11. The ingot pulling apparatus of claim 10, wherein each outlet has a longitudinal axis that is either (1) parallel to the pulling axis or (2) forms an angle of 45 degrees or less with the pulling axis.

12. 12. The ingot pulling apparatus of claim 11, wherein the longitudinal axis is parallel to the pulling axis.

13. 12. The ingot pulling apparatus of claim 11, wherein the longitudinal axis of each outlet forms an angle with the pulling axis of 45 degrees or less, 30 degrees or less, 25 degrees or less, or 10 degrees or less.

14. 14. An ingot pulling apparatus according to claim 10, wherein the shower plate is connected to a shutoff valve and moves between an open position and a closed position together with the shutoff valve.

15. 15. The ingot pulling apparatus according to claim 10, wherein the isolation valve defines a process gas plenum therein, the process gas plenum being in fluid communication with an inlet of the process gas supply assembly and a plurality of outlets of the shower plate.

16. 16. The ingot pulling apparatus according to claim 10, wherein the shower plate includes at least 5 openings, at least 10 openings, at least 20 openings, or at least 25 openings.

17. 17. An ingot pulling apparatus according to any one of claims 10 to 16, wherein the inlet is a first inlet and the ingot pulling apparatus includes a second inlet extending through the ingot pulling housing for introducing process gas into the upper segment chamber.

18. 18. An ingot pulling apparatus according to claim 10, wherein the lower segment includes a dome-shaped portion, and the upper segment is cylindrical, the diameter of the upper segment being smaller than the diameter of the lower segment.

19. 1. A method of forming a single crystal silicon ingot in an ingot pulling apparatus, the ingot pulling apparatus including: a crucible assembly for holding a silicon melt; an ingot pulling housing defining a growth chamber for pulling a single crystal silicon ingot from the silicon melt; the crucible assembly disposed within the growth chamber; the ingot pulling housing including a lower segment defining a lower segment chamber; the crucible assembly disposed within the lower segment chamber and further including an upper segment disposed above the lower segment to define an upper segment chamber; and an isolation valve movable between an open position in which the lower segment chamber is in fluid communication with the upper segment chamber and a closed position in which the lower segment chamber is isolated from the upper segment chamber, the method comprising: adding a charge of solid silicon to a crucible assembly; heating a crucible assembly containing a charge of silicon to form a silicon melt within the crucible assembly; contacting a silicon seed crystal with the silicon melt; pulling the silicon seed crystal along a pulling axis to grow a single crystal silicon ingot; Separating the single crystal silicon ingot from the melt; cooling the single crystal silicon ingot after separating it from the melt, with the ingot being entirely within the upper segment chamber, and the isolation valve being in an open position while cooling the single crystal silicon ingot; Directing a process gas through the upper segment chamber to the lower segment chamber while cooling the single crystal silicon ingot in the upper segment chamber; and The method includes: pulling a single crystal silicon ingot from an upper segment chamber, the isolation valve being in a closed position while the single crystal silicon ingot is being pulled.

20. Ingot pulling equipment a first inlet for introducing process gas directly into the lower segment chamber; a first process gas valve movable between an open position in which the first inlet is in fluid communication with the process gas source and a closed position in which process gas does not flow from the process gas source through the first inlet; a second inlet for introducing process gas directly into the upper segment chamber; and 20. The method of claim 19, wherein a second process gas valve is movable between an open position in which the second inlet is in fluid communication with the process gas source and a closed position in which process gas does not flow from the process gas source through the second inlet, and during cooling of the single crystal silicon ingot in the upper segment chamber, the first process gas valve is in the closed position and the second process gas valve is in the open position while cooling the single crystal silicon ingot.

21. 21. The method of claim 20, wherein the first process gas valve is in an open position and the second process gas valve is in a closed position while the single crystal silicon ingot is being pulled from the upper segment chamber.

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