Method for growing single crystal silicon ingots with inert gas control of silicon delivery tube - Patents.com

Abstract

A method for growing single crystal silicon ingots with inert gas control of the silicon supply tube is disclosed. An ingot pulling apparatus is also disclosed that includes a silicon funnel or flange extending radially from the silicon supply tube to reduce backflow of gas from the silicon supply tube into the growth chamber.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Non-provisional Patent Application No. 15 / 570,141, filed January 6, 2022, and U.S. Non-provisional Patent Application No. 15 / 570,146, filed January 6, 2022.

[0002] The field of the disclosure relates to methods of growing single crystal silicon ingots with inert gas control of the silicon supply tube, and ingot pulling apparatus that includes a silicon funnel or flange extending radially from the silicon supply tube to reduce backflow of gas from the silicon supply tube into the growth chamber. [Background technology]

[0003] Continuous Czochralski (CCz) is well suited for forming single crystal silicon ingots of 300 mm or 200 mm diameter. The continuous Czochralski process involves forming a single crystal silicon ingot from a melt of silicon while the ingot is growing and the melt is replenished by continuous or intermittent addition of solid polycrystalline silicon to the melt. The process may involve forming multiple ingots from the same melt while the hot zone remains at temperature (i.e., the melt is continuously present in the crucible assembly while multiple ingots are being grown).

[0004] Solid state silicon is added to the melt through a silicon feed tube that directs the silicon into the melt. Periodically, the silicon feed tube may become blocked, preventing silicon from passing through the tube. A clogged feed tube can halt ingot production and shut down the ingot puller, reducing throughput and increasing costs. To reduce clogging, an inert gas such as argon may be passed through the tube. However, the flow of inert gas can cause bubbles of the inert gas (e.g., argon bubbles) to form in the melt, affecting the void count in the resulting ingot and sliced ​​wafers. Customers expect continuous Czochralski grown wafers to have a relatively low void count, similar to standard batch Czochralski grown wafers.

[0005] A need exists for an ingot pulling apparatus and method of ingot formation that reduces blockage of silicon delivery tubes and does not result in the formation of excessive inert gas bubbles in the melt.

[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 disclosure is directed to a method of growing a monocrystalline silicon ingot in a continuous Czochralski process in an ingot puller. The ingot puller includes a housing defining a growth chamber, a crucible assembly disposed in the growth chamber, and a silicon feed tube for adding solid silicon to the crucible assembly. A melt of silicon is formed in the crucible assembly. Heat is applied to the melt in a stabilization stage. An inert gas is introduced into the silicon feed tube at a first inert gas feed rate during the stabilization stage. A surface of the melt is contacted with a seed crystal. A monocrystalline silicon ingot is withdrawn from the melt in an ingot growth stage. An inert gas is introduced into the silicon feed tube at a second inert gas feed rate during the ingot growth stage. The first inert gas feed rate is greater than the second inert gas feed rate.

[0008] Another aspect of the disclosure is directed to a method of growing a single crystal silicon ingot in a continuous Czochralski process in an ingot puller. The ingot puller includes a housing defining a growth chamber, a crucible assembly disposed in the growth chamber, and a silicon feed tube for adding solid silicon to the crucible assembly. A melt of silicon is formed in the crucible assembly. Heat is added to the melt in a stabilization stage. An inert gas is introduced into the silicon feed tube at a first inert gas feed rate during the stabilization stage. The first inert gas feed rate is between 2.5 and 3.5 slpm. A surface of the melt is contacted with a seed crystal. A single crystal silicon ingot is withdrawn from the melt in an ingot growth stage. An inert gas is introduced into the silicon feed tube at a second inert gas feed rate during the ingot growth stage. The second inert gas feed rate is between 2.5 and 3.5 slpm.

[0009] A further aspect of the present disclosure is directed to an ingot pulling apparatus for producing a single crystal silicon ingot. 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 melt. The crucible assembly is disposed within the growth chamber. The ingot pulling apparatus includes a silicon feed tube for adding solid silicon to the crucible assembly. A funnel extends at least partially into the silicon feed tube. The funnel and silicon feed tube are separated by a gap. A flange extends radially from the funnel or the silicon feed tube. The flange extends across at least a portion of the gap to reduce backflow of gas from the silicon feed tube into the growth chamber.

[0010] There are various refinements of the features mentioned 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 alone or in any combination into any of the above-mentioned aspects of the disclosure. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view of an example of an ingot pulling apparatus having a silicon charge disposed in a crucible assembly.

[0012] [Diagram 2] FIG. 2 is a cross-sectional view of the ingot pulling apparatus during the post-melt and stabilization stages.

[0013] [Diagram 3] FIG. 2 is a cross-sectional view of an ingot puller with a silicon seed crystal lowered into contact with the melt to begin the ingot growth stage.

[0014] [Figure 4]FIG. 2 is a cross-sectional view of an ingot pulling apparatus during an ingot growth stage.

[0015] [Diagram 5] FIG. 2 is a perspective view of a silicon delivery system that adds silicon to the crucible assembly.

[0016] [Figure 6] FIG. 2 is a detailed cross-sectional view of the ingot puller showing the silicon delivery tube.

[0017] [Figure 7] 1 is a detailed cross-sectional view of an embodiment of an ingot pulling apparatus showing a flange extending from a funnel.

[0018] [Figure 8] 1 is a detailed cross-sectional view of another embodiment of an ingot pulling apparatus showing a flange extending from the bottom end of the funnel.

[0019] [Figure 9] 1 is a simulation of the mass fraction of SiO in a silicon delivery tube during the ingot growth stage.

[0020] [Figure 10] 13 is a simulation of the mass fraction of SiO in the silicon delivery tube during the stabilization stage.

[0021] [Figure 11] A box plot of the defect counts for wafers grown with an argon gas flow rate of 12 slpm through the silicon supply tube (Crystal 1 and Crystal 2) and a wafer grown with an argon gas flow rate of 3 slpm through the silicon supply tube (Crystal 3) is shown.

[0022] Corresponding reference characters indicate corresponding parts throughout the drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present disclosure provides a method for growing single crystal silicon ingots in a continuous Czochralski process in an ingot puller and an ingot puller having a flange extending across a portion of the gap between a funnel and a silicon delivery tube, which may reduce downstream clogging of the silicon delivery tube.

[0024] An embodiment of an ingot pulling apparatus (or more simply "ingot puller") is indicated generally at "100" in FIG. 1. The ingot pulling apparatus 100 includes a crucible assembly 102 for holding a melt 104 (FIG. 2) of semiconductor or solar grade raw silicon. The crucible assembly 102 is supported by a susceptor 106. The ingot pulling apparatus 100 includes a crystal pulling housing 108 that defines a growth chamber 152 for pulling a silicon ingot 113 (FIG. 4) from the melt 104 along a pulling axis A.

[0025] The crucible assembly 102 has a sidewall 131 (FIG. 1) and one or more fluid barriers 121, 130 or "weirs" that separate the melt into different melt zones. In the illustrated embodiment, the crucible assembly 102 includes a first weir 121. The first weir 121 and the sidewall 131 define the silicon melt 104 and an outer melt zone 143 (FIG. 2) of the crucible assembly 102. The crucible assembly 102 includes a second weir 130 radially inward relative to the first weir 121 that defines the silicon melt 104 and an inner melt zone 127 of the crucible assembly 102. The inner melt zone 127 is a growth region in which the single crystal silicon ingot 113 (FIG. 4) is grown. The first weir 121 and the second weir 130 define an intermediate melt zone 132 of the crucible assembly 102 and the silicon melt 104 where the melt 104 may stabilize as it moves toward the inner melt zone 127. The first weir 121 and the second weir 130 each have at least one opening formed therein to allow the molten silicon to flow radially inward toward the inner melt zone 127.

[0026] In the illustrated embodiment, the first weir 121, the second weir 130, and the sidewall 131 each have a generally annular shape. The first weir 121, the second weir 130, and the sidewall 131 may be part of three nested crucibles joined at the bottom or floor 129 of the crucible assembly 102 (i.e., the first weir 121 and the second weir 130 are sidewalls of two crucibles nested within a larger crucible). The configuration of the crucible assembly depicted in Figures 1-4 is exemplary. In other embodiments, the crucible assembly 102 has a single floor with weirs extending upward from the floor 129 (i.e., no nested crucibles). Optionally, floor 129 may be flat rather than curved and / or dams 121, 130 and / or sidewall 131 may be straight. Additionally, although the illustrated crucible assembly 102 is shown as having two dams, in other embodiments the crucible assembly may have a single dam or no dams.

[0027] The susceptor 106 is supported by a shaft 105. The susceptor 106, crucible assembly 102, shaft 105, and ingot 113 (FIG. 4) have a common longitudinal axis or "pull axis" A.

[0028] Within the ingot pulling apparatus 100, a pulling mechanism 114 is provided for growing and pulling an ingot 113 (FIG. 4) from the melt 104. The pulling mechanism 114 includes a pulling cable 118, a seed holder or chuck 120 coupled to one end of the pulling cable 118, and a seed crystal 122 coupled to the seed holder or chuck 120 to initiate crystal growth. One end of the pulling cable 118 is connected to a pulley (not shown) or drum (not shown) or other suitable type of lifting mechanism, such as a shaft, and the other end is connected to the chuck 120, which holds the seed crystal 122. In operation, the seed crystal 122 is lowered to contact the surface of the melt 104 (FIG. 3). The pulling mechanism 114 is actuated to raise the seed crystal 122, thereby pulling a single crystal ingot 113 (FIG. 4) from the melt 104.

[0029] 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 raises and lowers the crucible assembly 102 along the pulling axis A during the growth process. For example, the crucible assembly 102 can be in a lowest position (near the bottom heater 126) where a charge of solid phase polycrystalline silicon 133 previously added to the crucible assembly 102 is melted. Crystal growth begins by bringing the melt 104 (FIG. 2) into contact with the seed crystal 122 and lifting the seed crystal 122 with the lift mechanism 114.

[0030] The crystal drive unit (not shown) may also rotate the pulling cable 118 and ingot 113 (FIG. 4) in a direction opposite (e.g., counter-rotation) from the direction that the crucible drive unit 107 rotates the crucible assembly 102. In embodiments using co-directional rotation, the crystal drive unit may rotate the pulling cable 118 in the same direction that the crucible drive unit 107 rotates the crucible assembly 102.

[0031] According to the Czochralski single crystal growth process, a quantity of solid phase silicon 133 (FIG. 1), such as polycrystalline silicon or polysilicon, is charged to the crucible assembly 102. Semiconductor or solar grade feedstock material introduced into the crucible assembly 102 is melted by heat provided by one or more heating elements. The size of the solid phase silicon charge 133 corresponds to the desired size of the melt at the start of ingot growth or, as in other embodiments, a smaller charge is used and additional silicon is added by the silicon supply system 200 to form the initial volume of melt present during the start of ingot growth.

[0032] The ingot pulling apparatus 100 includes bottom insulation 110 and side insulation 124 for retaining heat in the pulling apparatus 100. In the illustrated embodiment, the ingot pulling apparatus 100 includes a bottom heater 126 disposed below a crucible floor 129. The crucible assembly 102 may be moved relatively close to the bottom heater 126 to melt the polycrystalline material charged in the crucible assembly 102.

[0033] The silicon melt 104 is stabilized in a stabilization phase prior to the ingot growth phase. In some embodiments, the stabilization phase includes at least the period between the formation of the melt (after melting) and the contact of the surface of the melt with the seed crystal. In some embodiments, the stabilization phase also includes the period during which silicon is melted in the crucible assembly 102 (i.e., melting of the initial charge and any other silicon added to form the initial melt).

[0034] To form an ingot, after the melt is stabilized in the stabilization stage, the seed crystal 122 contacts the surface 111 of the melt 104, as shown in FIG. 3. A pulling mechanism 114 operates to pull the seed crystal 122 from the melt 104 in the ingot growth stage. Referring now to FIG. 4, the ingot 113 includes a crown portion 142 where the ingot transitions outward from the seed crystal 122 and tapers to reach a target diameter. The ingot 113 includes a constant diameter portion 145, i.e., a cylindrical crystal "body," 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) that tapers in diameter after the body 145. Once the diameter is small enough, the ingot 113 is separated from the melt 104.

[0035] The ingot pulling apparatus 100 includes a side heater 135 and a susceptor 106 surrounding the crucible assembly 102 for maintaining the temperature of the melt 104 during crystal growth. The side heater 135 is disposed 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 allows them to operate as described herein. In some embodiments, the heaters 135, 126 are resistive heaters. The side heater 135 and the bottom heater 126 may be controlled by a control system (not shown) such that the temperature of the melt 104 is controlled throughout the pulling process.

[0036] The ingot pulling apparatus 100 may include a heat shield 151. The heat shield 151 may cover the ingot 113 and may be positioned within the crucible assembly 102 during crystal growth (FIG. 4). The ingot pulling apparatus 100 may include an inert gas system to introduce and withdraw an inert gas, such as argon, from the growth chamber 152.

[0037] The ingot pulling apparatus 100 also includes a silicon feed system 200 for introducing solid silicon (e.g., polycrystalline or single crystal silicon scrap feedstock) into the crucible assembly 102, and in particular the outer melt zone 143. The solid silicon may be added continuously during ingot growth or intermittently during crystallization to maintain a substantially constant melt height level and volume during growth of the ingot 113. The solid silicon provided by the silicon feed system 200 to the crucible assembly 102 may be, for example, granular, chunky, chip-like, or combinations thereof. The silicon feed system 200 adds the solid silicon into and through a silicon feed tube 214. Referring now to FIG. 5, an example of a silicon feed system 200 of the present disclosure is shown. The silicon feed system 200 includes a canister 204 that holds the solid silicon. The canister 204 includes a removable lid 207 that seals the canister 204. The canister 204 also includes a funnel 211 that directs the silicon into a feed tray 260 positioned below the canister 204 .

[0038] To move silicon from the canister 204 to the feed tube 214, the silicon feed system 200 includes a feed tray 260 disposed below the canister 204 and extending between the canister 204 and a port 229 (FIG. 6) extending through the ingot pulling housing 108. The feed tray 260 is disposed above and connected to a vibrator 262. When the vibrator 262 is powered, the feed tray 260 vibrates and silicon is transported from the canister 204 across the feed tray 260. The silicon is discharged from the feed tray 260 into a port opening 232 (FIG. 6) (e.g., through a tube or chute (not shown) disposed below the feed tray 260). The silicon falls through the port opening 232 into a funnel 222 disposed below the port 229. From the funnel 222, the silicon falls into the silicon tube 214. Silicon may be added to maintain the position of the melt surface constant, which may be controlled by the power supplied to the vibrator 262 .

[0039] The port 229 and the silicon supply tube 214 are sealed with a canister 204 to isolate the growth chamber 152 (FIG. 1) of the ingot pulling apparatus 100 from the surrounding environment. For example, the silicon supply system 200 may include an outer housing 252 within which the other components of the supply system are disposed. An inert gas, such as argon, may be introduced into the outer housing 252 from an inert gas supply vessel 255. The inert gas passes through a port opening 232 (FIG. 6) and into the silicon supply tube 214.

[0040] Silicon delivery system 200 is exemplary and any delivery system may be used that allows silicon to be introduced into crucible assembly 102. For example, other delivery systems may include liquid delivery systems.

[0041] 6, the tube 214 includes a receiver 225 and a main section 227 disposed below the receiver 225. The funnel 222 is partially disposed within the receiver 225 of the silicon supply tube 214. The receiver 225 of the tube includes a constant diameter portion 231 and a tapered portion 223 that tapers to the main section 227 of the tube 214. The main section 227 of the tube 214 has an angled portion 243 (i.e., the portion that extends radially in the pulling apparatus 100) and a terminal portion 245 that extends from the angled portion 243. The silicon tube 214 includes an upper end 221 and a lower end 249.

[0042] According to embodiments of the present disclosure, the amount of inert gas introduced into port 229 and traveling through funnel 222 and silicon tube 214 is adjusted to reduce clogging downstream of tube 214. For example, different flow rates may be used during the stabilization stage and the ingot growth stage. During the stabilization stage, inert gas is introduced into the silicon feed tube at a first inert gas feed rate. During the ingot growth stage, inert gas is introduced into the silicon feed tube at a second inert gas feed rate. The first inert gas feed rate is greater than the second inert gas feed rate. For example, the ratio of the first inert gas feed rate to the second inert gas feed rate may be at least 5:4, at least 4:3, at least 3:2, or at least 2:1. In some embodiments, the first inert gas feed rate is greater than 3 slpm and the second inert gas feed rate is between 1 slpm and 3 slpm. For example, according to some specific embodiments, the first inert gas feed rate and the second inert gas feed rate are each between 2.5 and 3.5 slpm.

[0043] It should be noted that the above-mentioned inert gas feed amounts and ratios may be applied to the entirety of each stabilization or inert gas stage, or, in some embodiments, to at least 75% of each stage, or at least 85%, at least 95%, or at least 99% of each stage.

[0044] In some embodiments, there may be a gap 233 (e.g., an open gap as shown in FIG. 6) between the funnel 222 and the silicon supply tube 214. Some inert gas may exit through the gap 233 rather than traveling the entire length of the tube 214. The flow rates and / or flow rate ratios described herein may refer to the amount of gas introduced through the port opening 232 (i.e., upstream of the gas passing through the gap 223).

[0045] 7-8, in some embodiments, the silicon supply tube 214 and / or funnel 222 may be modified as compared to conventional tubes and funnels. The supply tube 214 and / or funnel may reduce clogging of the tube 214 as compared to conventional tubes and funnels. The silicon supply tube 214 and / or funnel 222 described below may be used in combination with the inert gas flow rates and ratios described above, or the flow rates and ratios may be used without the modified tube 214 and funnel 222, and the modified tube 214 and funnel 222 may be used with different inert gas flow rates and ratios.

[0046] 7, the funnel 222 extends at least partially into the silicon feed tube 214. The funnel 222 includes a tapered portion 237 that is disposed below the opening 232 of the port 229. The funnel 222 has a chute portion 240 that extends partially into the silicon feed tube 214. The funnel 222 has an upper end 212 and a lower end 215, the lower end 215 being disposed within the silicon feed tube 214. The silicon feed tube 214 includes a receptacle 225 in which the chute portion 240 of the funnel 222 is partially disposed. The receptacle 225 has a larger diameter than the main portion 227 of the tube 214.

[0047] The funnel 222 and the silicon supply tube 214 are separated by a gap 219. The ingot pulling apparatus 100 includes a flange 230 extending radially from the funnel 222. The flange 230 extends across at least a portion of the gap 219 (e.g., across the entire gap 219 as shown in FIG. 7 or partially across the gap 219 as shown in FIG. 8) to reduce backflow of gas from the silicon supply tube 214 into the growth chamber 152 (FIG. 1).

[0048] In the embodiment shown in FIG. 7, the flange 230 extends from the funnel 222 and is disposed above (i.e., directly above) the silicon feed tube 214. The flange 230 contacts the top end 221 of the feed tube 214. In the embodiment shown in FIG. 8, the flange 230 extends from the funnel 222 and is disposed within the silicon feed tube 214 (e.g., the receptacle 225 of the tube 214). The flange 230 extends only partially across a portion of the gap 219. In the illustrated embodiment, the flange 230 extends from the bottom end 215 of the funnel 222. In some embodiments, the ingot pulling apparatus of FIG. 7 may be modified to also include the flange shown in FIG. 8 (i.e., the ingot pulling apparatus 100 includes both flanges). The flange 230 of FIG. 7 and the flange 230 of FIG. 8 may extend from either the feed tube 214 or the funnel 222.

[0049] The flange 230 may be made of quartz (e.g., devitrified quartz) or silicon carbide. The flange 230 may be a separate ring that is connected to the tube 214 or funnel 222, or may be integral with the tube 214 or funnel 222 (e.g., as a single manufactured piece).

[0050] In embodiments in which the ingot pulling apparatus is modified from conventional apparatus, unless otherwise noted, it should be noted that generally any ingot pulling apparatus that includes a flange extending across a portion of the gap to reduce backflow of gas from the silicon supply tube into the growth chamber may be used. The ingot pulling apparatus shown in Figures 7-8 is an exemplary apparatus, and other arrangements of silicon tubes, funnels, and / or flanges may be used. Although silicon supply tube 214 has been described with reference to the addition of silicon, tube 214 may also be used to add dopants or quartz cullet to the silicon melt.

[0051] Compared to conventional methods, the disclosed method for growing single crystal silicon ingots in a continuous Czochralski process has several advantages. Without being bound to a particular theory, clogging of the feed tube is believed to be caused by the formation of silicon oxide (SiO x It is believed that the deposition of silicon oxide is caused by the chemical vapor deposition of silicon dioxide. Silicon oxide vaporizes from the silicon melt and rises up the inside of the feed tube due to buoyancy. Once inside the feed tube, the silicon oxide rises and encounters a cooler region, causing the precipitation of silicon metal and silicon dioxide according to the following equation: 2SiO → SiO2 + Si………(1) It is believed that by keeping the concentration of SiO below 1 wt%, clogging in the supply tube can be prevented. It is more difficult to keep the concentration of SiO down during the stabilization phase due to the higher temperatures used to keep the silicon molten. Clogging of the supply tube will halt ingot production and shut down the ingot puller. By controlling the flow rate of inert gas through the silicon supply tube to be high during the stabilization phase and relatively low during the ingot growth phase, the flow rate is increased during the high temperature stabilization phase (stabilization gives more clogging than the ingot growth phase due to the high temperature) and decreased during the ingot growth phase, reducing inert gas bubbles that cause defects in the ingot.

[0052] In embodiments where the ingot pulling apparatus includes a flange extending radially from the funnel or silicon supply tube and extending across at least a portion of the gap between the funnel and the supply tube, the flange reduces backflow of gas from the silicon supply tube into the growth chamber.

[0053] In embodiments where the inert gas supply rate is near 3 slpm (e.g., 2.5 slpm to 3.5 slpm) during both the stabilization and ingot growth stages, the concentration of SiO in the silicon supply tube can be maintained at 1.0 wt%, which is believed to be the threshold at which CVD reactions occur, during all stages of the ingot growth process. EXAMPLES

[0054] The processes of the present disclosure are further illustrated by the following examples, which should not be viewed in a limiting sense. Example 1: SiO mass fraction in silicon delivery tube during stabilization and ingot growth stages

[0055] FIG. 9 is a simulation of the mass fraction of silicon oxide (SiO) during the ingot growth phase, and FIG. 10 is a simulation of the mass fraction of SiO during the stabilization phase. During the ingot growth phase (FIG. 9), the flow of SiO to the silicon supply tube was 0.0132 g / s. During the stabilization phase (FIG. 10), the flow of SiO to the silicon supply tube was 0.0142 g / s. As can be seen, the stabilization phase contained a higher mass fraction of SiO compared to the ingot growth phase. As shown in FIG. 10, the concentration of SiO was higher at the junction between the tube angle and the tube end (i.e., the lower bend of the tube), where most clogging occurs. During stabilization, the temperature of this junction was between 900° C. and 1000° C., which is within the critical temperature range for the CVD reaction. Example 2: Reducing wafer defects by reducing inert gas flow rate

[0056] Three single crystal silicon ingots were made by continuous Czochralski using the ingot puller shown in Figure 1. Crystals 1 and 2 were grown with an argon flow rate of 12 slpm through the silicon supply tube 214, and crystal 3 was grown with a flow rate of 3 slpm. The defect counts on the surfaces of wafers sliced ​​from the ingots were measured for each ingot and are shown in Figure 11. As shown in Figure 11, the ingot grown with an argon flow rate of 3 slpm through the silicon supply tube 214 had significantly fewer defects.

[0057] As used herein, when used in conjunction with a range of a dimension, concentration, temperature, or other physical or chemical property or characteristic, the terms "about," "substantially," "essentially," and "about" are meant to cover variations that may exist at the upper and / or lower limits of the property or property range, including variations that are due, for example, to rounding, measurement method, or other statistical variations.

[0058] 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 elements. The terms "comprises," "includes," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. Use of specific directional terms (e.g., "top," "bottom," "side," etc.) is for convenience of description and does not require a particular orientation of the items described.

[0059] Since various changes may be made in the above 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. 1. A method for growing a single crystal silicon ingot in a continuous Czochralski process in an ingot puller, the ingot puller comprising: a housing defining a growth chamber; a crucible assembly disposed in the growth chamber; and a silicon feed tube for adding solid silicon to the crucible assembly, the method comprising: forming a melt of silicon in a crucible assembly; applying heat to the melt in a stabilization step; introducing an inert gas into a silicon supply tube at a first inert gas feed rate during the stabilization phase, wherein the inert gas passes through the silicon supply tube and into the growth chamber during the stabilization phase; contacting the surface of the melt with a seed crystal; drawing a single crystal silicon ingot from the melt in an ingot growth stage; introducing the inert gas into the silicon supply tube at a second inert gas feed rate during the ingot growth stage, wherein the first inert gas feed rate is greater than the second inert gas feed rate, and the inert gas passes through the silicon supply tube and into the growth chamber during the ingot growth stage; A method comprising:

2. The ratio of the first inert gas supply rate to the second inert gas supply rate is at least 5:

4. The method of claim 1.

3. The first inert gas supply rate is greater than 3 slpm, and the second inert gas supply rate is 1 slpm to 3 slpm. The method of claim 1.

4. The inert gas is argon. The method of claim 1.

5. The silicon supply tube is positioned below a funnel, and the inert gas flows through the funnel into the silicon supply tube. The method of claim 1.

6. the ingot puller includes a silicon supply system having a supply tray, the silicon supply system being sealed, and the inert gas being introduced into the silicon supply system from an inert gas supply vessel; The method of claim 5.

7. the crucible assembly having a weir and a sidewall, the weir and the sidewall defining an outer melt zone between the weir and the sidewall, and the method including introducing silicon into the silicon feed tube while drawing a single crystal silicon ingot from the melt, the silicon passing through the silicon feed tube and into the outer melt zone; The method of claim 1.

8. the stabilization step extends at least between the formation of the melt and the contact of the surface of the melt with the seed crystal; The method of claim 1.

9. the stabilization step includes melting silicon disposed in the crucible assembly; The method of claim 8.

10. 1. A method for growing a single crystal silicon ingot in a continuous Czochralski process in an ingot puller, the ingot puller comprising: a housing defining a growth chamber; a crucible assembly disposed in the growth chamber; and a silicon feed tube for adding solid silicon to the crucible assembly, the method comprising: forming a melt of silicon in a crucible assembly; applying heat to the melt in a stabilization step; introducing an inert gas into a silicon supply tube at a first inert gas feed rate during the stabilization stage, wherein the first inert gas feed rate is between 2.5 and 3.5 slpm, and the inert gas passes through the silicon supply tube and into the growth chamber during the stabilization stage; contacting the surface of the melt with a seed crystal; drawing a single crystal silicon ingot from the melt in an ingot growth stage; introducing the inert gas into the silicon supply tube at a second inert gas feed rate during the ingot growth stage, wherein the second inert gas feed rate is between 2.5 and 3.5 slpm, and the inert gas passes through the silicon supply tube and into the growth chamber during the ingot growth stage; A method comprising:

11. The inert gas is argon. The method of claim 10.

12. The first inert gas supply rate and the second inert gas supply rate are each about 3.0 slpm. The method of claim 10.

13. The ratio of the first inert gas supply amount to the second inert gas supply amount is at least 4:

3. The method of claim 1.

14. The ratio of the first inert gas supply amount to the second inert gas supply amount is at least 2:

1. The method of claim 1.

15. An ingot pulling apparatus for producing a single crystal silicon ingot, the ingot pulling apparatus comprising: a crucible assembly for holding a silicon melt; a crystal pulling housing defining a growth chamber for pulling a silicon ingot from the melt, the crucible assembly being disposed within the growth chamber; a silicon feed tube for adding solid silicon to the crucible assembly, the silicon feed tube extending into the growth chamber; a funnel extending at least partially into the silicon supply tube, the funnel and the silicon supply tube being separated by a gap; a flange extending radially from the funnel, the flange extending across at least a portion of the gap to reduce backflow of gas from the silicon supply tube into the growth chamber, the flange being positioned above the silicon supply tube and contacting an upper end of the silicon supply tube, the funnel extending through the flange; and An ingot pulling apparatus comprising:

16. The flange is a quartz ring.

16. An ingot pulling apparatus according to claim 15.

17. The silicone supply tube includes a receiving portion and a main portion having a diameter smaller than that of the receiving portion, and the funnel is at least partially disposed within the receiving portion.

16. An ingot pulling apparatus according to claim 15.

18. The flange and the crystal pulling housing are separated by a gap.

16. An ingot pulling apparatus according to claim 15.

19. The silicone supply tube includes a receiving portion and a main portion having a diameter smaller than that of the receiving portion, and the funnel is at least partially disposed within the receiving portion.

16. An ingot pulling apparatus according to claim 15.

20. An ingot pulling apparatus for producing a single crystal silicon ingot, the ingot pulling apparatus comprising: a crucible assembly for holding a silicon melt; a crystal pulling housing defining a growth chamber for pulling a silicon ingot from the melt, the crucible assembly being disposed within the growth chamber; a silicon feed tube for adding solid silicon to the crucible assembly, the silicon feed tube extending into the growth chamber; a funnel extending at least partially into the silicon supply tube, the funnel and the silicon supply tube being separated by a gap; a flange extending radially from a lower end of the funnel, the flange extending across at least a portion of the gap to reduce backflow of gas from the silicon supply tube into the growth chamber, the flange being positioned within the silicon supply tube, the flange having an opening through which solid silicon passes; and An ingot pulling apparatus comprising:

21. the flange extending only partially across the gap; 21. An ingot pulling apparatus according to claim 20.

22. The flange is made of quartz.

21. An ingot pulling apparatus according to claim 20.

23. The flange extends only partially across the gap.

21. An ingot pulling apparatus according to claim 20.

24. An ingot pulling apparatus for producing a single crystal silicon ingot, comprising: a crucible assembly for holding a silicon melt; a crystal pulling housing defining a growth chamber for pulling a silicon ingot from the melt, the crucible assembly being disposed within the growth chamber; a silicon feed tube for adding solid silicon to the crucible assembly, the silicon feed tube extending into the growth chamber; a funnel extending at least partially into the silicon supply tube, the funnel and the silicon supply tube being separated by a gap; a flange extending radially from the funnel, the flange extending across at least a portion of the gap to reduce backflow of gas from the silicon supply tube into the growth chamber, the flange being disposed within the silicon supply tube; and An ingot pulling apparatus comprising:

25. The flange is made of quartz.

25. The ingot pulling apparatus of claim 24.

26. An ingot pulling apparatus for producing a single crystal silicon ingot, said ingot pulling apparatus comprising: a crucible assembly for holding a silicon melt; a crystal pulling housing defining a growth chamber for pulling a silicon ingot from the melt, the crucible assembly being disposed within the growth chamber; a silicon feed tube for adding solid silicon to the crucible assembly, the silicon feed tube extending into the growth chamber; a funnel extending at least partially into the silicon supply tube, the funnel and the silicon supply tube being separated by a gap; a flange extending radially from the silicon supply tube, the flange extending completely across the gap to reduce backflow of gas from the silicon supply tube into the growth chamber, the flange being positioned above the silicon supply tube and contacting an upper end of the silicon supply tube, the funnel extending through the flange; and An ingot pulling apparatus comprising:

27. ​​The flange is made of quartz.

27. An ingot pulling apparatus as claimed in claim 26.

28. The silicone supply tube includes a receiving portion and a main portion having a diameter smaller than that of the receiving portion, and the funnel is at least partially disposed within the receiving portion.

27. An ingot pulling apparatus as claimed in claim 26.

29. The flange and the crystal pulling housing are separated by a gap.

27. An ingot pulling apparatus as claimed in claim 26.

30. An ingot pulling apparatus for producing a single crystal silicon ingot, comprising: a crucible assembly for holding a silicon melt; a crystal pulling housing defining a growth chamber for pulling a silicon ingot from the melt, the crucible assembly being disposed within the growth chamber; a silicon feed tube for adding solid silicon to the crucible assembly, the silicon feed tube extending into the growth chamber; a funnel extending at least partially into the silicon supply tube, the funnel and the silicon supply tube being separated by a gap; a flange extending radially from the silicon supply tube, the flange extending completely across the gap to reduce backflow of gas from the silicon supply tube into the growth chamber, the flange being positioned within the silicon supply tube, the flange having an opening through which solid silicon passes; and An ingot pulling apparatus comprising:

31. The flange is made of quartz.

31. An ingot pulling apparatus as claimed in claim 30.

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