A guide tube for silicon single crystal growth

Abstract

This invention belongs to the technical field of single crystal growth equipment, specifically relating to a guide tube for silicon single crystal growth, including a tube body, a support ring, and multiple positioning rods. This invention uses the contact state between the bottom end of the positioning rod and the liquid surface as a calibration benchmark to indicate the theoretical distance from the lower edge of the guide tube to the silicon liquid surface, thereby improving process stability. By forming a multi-reference point plane through circumferentially evenly distributed positioning rods, and observing whether they simultaneously contact the same plane, the overall levelness of the thermal field is verified, thereby reducing crystal defects caused by levelness deviations and ensuring the high precision and high stability requirements of silicon single crystal preparation.

Description

Technical Field

[0001] This utility model belongs to the technical field of single crystal growth equipment, specifically relating to a guide tube for silicon single crystal growth. Background Technology

[0002] In the Czochralski process for growing single crystals of semiconductor silicon, the flow tube is the core component of the single crystal furnace. Its structure directly affects the longitudinal temperature gradient distribution and argon gas flow state during the silicon single crystal growth process, thereby indirectly playing a key role in the single crystal growth rate, crystal quality, and some parameters.

[0003] However, the existing flow guide structure still has the following drawbacks:

[0004] 1. The distance between the lower edge of the guide tube and the surface of the growing silicon liquid is the core parameter for controlling the temperature gradient of the thermal field, which affects the morphology of the solid-liquid interface of the crystal and the segregation of impurities. However, the existing guide tubes lack distance calibration function, and it is impossible to accurately calibrate and monitor this distance in the high-temperature crystal growth environment, which undermines the stability of the process.

[0005] Second, the level deviation of the overall assembly of the hot zone will cause the axis of the guide tube to deviate from the crystal pulling direction, resulting in an asymmetric distribution of the argon gas flow field and radial temperature gradient distortion, which will ultimately affect the uniformity of the oxygen content of the crystal and the risk of dislocation multiplication. However, the existing guide tube does not have a level calibration function and cannot achieve rapid verification of the level state. Utility Model Content

[0006] The purpose of this invention is to provide a guide tube for silicon single crystal growth, which solves the technical problem that the existing technology lacks distance calibration and horizontal calibration functions.

[0007] This utility model discloses a flow guide tube for silicon single crystal growth, comprising:

[0008] The cylindrical body has an axially continuous hollow channel;

[0009] A support ring is coaxially fixedly connected to the top end of the cylinder, and the inner diameter of the support ring matches the inner diameter of the top opening of the hollow channel.

[0010] Multiple positioning rods are evenly distributed circumferentially at the bottom end of the cylinder and are detachably connected to the cylinder, with the bottom end of the positioning rods extending downward beyond the bottom end of the cylinder.

[0011] This application improves process stability by using the contact state between the bottom of the positioning rod and the liquid surface as a calibration benchmark to indicate the theoretical distance from the lower edge of the guide tube to the silicon liquid surface. By forming a multi-reference point plane with circumferentially evenly distributed positioning rods, and then observing whether they simultaneously contact the same plane, the overall levelness of the thermal field is verified, thereby reducing crystal defects caused by levelness deviation and ensuring the high precision and high stability requirements of silicon single crystal preparation.

[0012] Based on the above technical solution, the solution of this application can be further improved as follows:

[0013] Preferably, the positioning rod comprises:

[0014] L-shaped bar;

[0015] A limiting block is located at the end of the short arm of the L-shaped rod;

[0016] The bottom sidewall of the cylinder has multiple insertion holes, through which the L-shaped rod can pass as a whole, and the limiting block abuts against the bottom outer wall of the cylinder. This solution achieves accurate calibration, horizontal alignment, and rapid assembly and disassembly, significantly improving the stability and controllability of the process, and has high engineering application value.

[0017] Preferably, it includes:

[0018] A flow guide ring is coaxially fixed to the bottom end of the cylinder, and the inner diameter of the flow guide ring is smaller than the inner diameter of the bottom opening of the hollow channel. This design reduces the direct impact of airflow on the liquid surface, ensuring the stability of the crystal-melt interface. It also guides the airflow to diffuse radially outward along the liquid surface, thereby effectively carrying away impurities such as silicon oxide volatilized from the melt surface and preventing impurities from accumulating at the crystal-melt interface, thus improving crystal purity.

[0019] Preferably, the inner circumferential wall of the guide ring is provided with multiple notches, which match the long arm of the L-shaped rod. By adopting this solution, the long arm of the L-shaped rod can be radially constrained, thereby forming a three-dimensional fixation together with the axial limit of the limiting block, thus enhancing the stability of the positioning rod.

[0020] Preferably, the outer circumference of the guide ring extends upward to form a gradually expanding neck, and the inner circumferential surface of the gradually expanding neck is fitted and fixed to the outer circumferential surface of the bottom end of the cylinder. This solution increases the contact area, effectively disperses stress, avoids loosening or cracking at the connection, and ensures the sealing of the connection through tight fitting. Furthermore, the use of conical surface mating forms a mechanical interlock, achieving axial limiting, increasing connection stability, and ensuring flow field stability.

[0021] In some embodiments, such as Figure 2 As shown.

[0022] Preferably, the cylinder comprises an upper conical section, a middle straight section, and a lower conical section connected sequentially from top to bottom, and the cross-sections of the upper and lower conical sections gradually taper from top to bottom. This design can guide the airflow direction, optimize the airflow field, and thus improve the crystal quality, process stability, and equipment reliability of silicon single crystal growth.

[0023] Preferably, the outer wall of the top end of the upper conical cylinder extends radially outward to form a flange, and the top surface of the flange is fitted and fixed to the bottom surface of the support ring. This solution achieves large-area surface contact, thereby significantly increasing the connection stiffness, reducing stress concentration, improving load-bearing capacity, and preventing the connection from loosening or falling off.

[0024] Preferably, the bottom end of the upper conical section extends axially downward to form a straight neck, and the outer circumferential surface of the straight neck is fitted and fixed to the inner circumferential surface of the top end of the middle straight section. With this solution, a large-area sleeve fit and fixation are performed, thereby significantly improving the connection performance by utilizing the increased contact area, while using the conical structure to achieve axial limiting and ensure the stability of the flow field.

[0025] Preferably, the bottom end of the straight cylindrical section extends axially downward to form a tapered neck, and the outer circumferential surface of the tapered neck is fitted and fixed to the inner circumferential surface of the top end of the lower conical section. This solution increases the contact area, effectively disperses stress, avoids loosening or cracking at the connection, and ensures the sealing of the connection through the tight fit between the two. Furthermore, the use of the conical surface fit forms a mechanical interlock, achieving axial limiting, increasing the stability of the connection, and also ensuring the stability of the flow field.

[0026] Preferably, the support ring is provided with an observation hole; with this solution, it is convenient for operators to check the status of the quartz crucible through the observation hole during the crystal growth process, so as to detect safety risks in the production process in a timely manner.

[0027] Through the above technical solution, this utility model achieves the following beneficial effects:

[0028] 1. This application uses the contact state between the bottom end of the positioning rod and the liquid surface as the calibration benchmark to indicate the theoretical distance from the lower edge of the guide tube to the silicon liquid surface, thereby improving the process stability. By forming a multi-reference point plane with circumferentially evenly distributed positioning rods, it is observed whether they simultaneously contact the same plane to verify the overall levelness of the thermal field, thereby reducing crystal defects caused by levelness deviation and ensuring the high precision and high stability requirements of silicon single crystal preparation.

[0029] 2. By setting a flow guide ring, this application reduces the direct impact of airflow on the liquid surface, ensuring the stability of the crystal-melt interface; it also guides the airflow to diffuse radially outward along the liquid surface, thereby effectively removing impurities such as silicon oxide (SiO) volatilized from the melt surface, preventing impurities from accumulating at the crystal-melt interface, thus improving crystal purity. Attached Figure Description

[0030] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of the guide tube for silicon single crystal growth according to a specific embodiment of this application;

[0032] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0033] Figure 3 for Figure 1 The top view of the guide tube used for silicon single crystal growth is shown.

[0034] Figure 4 for Figure 1 The diagram shows the working principle of the guide tube used for silicon single crystal growth.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1. Cylinder body; 101. Hollow channel; 102. Insertion hole; 11. Upper conical section; 1101. Flange; 1102. Straight neck; 12. Middle straight section; 1201. Gradually narrowing neck; 13. Lower conical section;

[0037] 2. Support ring; 201. Observation hole;

[0038] 3. Positioning rod; 31. L-shaped rod; 32. Limiting block;

[0039] 4. Guide ring; 401. Notch; 402. Gradually expanding neck. Detailed Implementation

[0040] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0041] The terms “first” and “second” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as “first” or “second” may explicitly or implicitly include one or more of the stated features.

[0042] In this application, unless otherwise expressly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0043] To better understand the above technical solutions, the following will provide a detailed description of the technical solutions in conjunction with the accompanying drawings and specific embodiments.

[0044] Example:

[0045] like Figure 1 As shown in the embodiment of this application, a guide tube for silicon single crystal growth is disclosed, which can calibrate the distance from the lower edge of the guide tube to the surface of the silicon liquid during crystal growth, and can also quickly determine and verify the horizontal status of the overall assembly of the thermal field. Its specific structure includes: a tube body 1, a support ring 2 and multiple positioning rods 3.

[0046] The cylinder 1 is the main structure of the guide tube, with an axially through hollow channel 101, which is used to guide the argon gas flow along a preset path and optimize the longitudinal temperature gradient by limiting the thermal radiation range, thereby promoting stable unidirectional solidification at the crystal-melt interface.

[0047] The support ring 2, in cooperation with the upper structure of the thermal field, enables the installation and fixation of the guide tube. It is coaxially fixed to the top of the tube 1, ensuring the verticality of the thermal field and preventing the eccentric growth of crystals. Furthermore, the inner diameter of the support ring 2 matches the inner diameter of the top opening of the hollow channel 101, thus avoiding the generation of airflow turbulence.

[0048] Multiple positioning rods 3 are evenly distributed around the bottom of the cylinder 1 and are detachably connected to the cylinder 1, with the bottom ends of the positioning rods 3 extending downward beyond the bottom end of the cylinder 1.

[0049] For example, the cylinder 1 and the support ring 2 are preferably made of molybdenum material, which has strong resistance to thermal radiation, increases the longitudinal temperature gradient of the thermal field, and improves the crystal growth rate; at the same time, the segregation of molybdenum material in silicon is small (5E10-8), and the impact on metal contamination of single crystal is relatively small.

[0050] This invention uses the contact state between the bottom end of the positioning rod 3 and the liquid surface as a calibration benchmark to indicate the theoretical distance from the lower edge of the guide tube to the silicon liquid surface, thereby improving process stability. By forming a multi-reference point plane through the circumferentially evenly distributed positioning rods 3, and then observing whether they simultaneously contact the same plane, the overall levelness of the thermal field is verified, thereby reducing crystal defects caused by levelness deviation and ensuring the high precision and high stability requirements of silicon single crystal preparation.

[0051] In some embodiments, such as Figure 2 As shown, the positioning rod 3 includes:

[0052] The L-shaped rod 31 consists of a long arm and a short arm that are perpendicular to each other. The long arm extends axially and its bottom end extends beyond the bottom end of the cylinder 1. It is used to calibrate the liquid surface distance or contact the liquid surface, while the short arm extends radially. The L-shaped design can reduce the interference with the airflow and avoid the formation of turbulence.

[0053] The limiting block 32 is located at the end of the short arm of the L-shaped rod 31 to prevent the L-shaped rod 31 from falling off axially.

[0054] The bottom side wall of the cylinder 1 has multiple insertion holes 102, the number of which matches the positioning rod 3. The hole diameter is slightly larger than the diameter of the L-shaped rod 31, allowing the rod to be inserted freely but restricting excessive shaking, so that the L-shaped rod 31 can pass through the insertion hole 102 as a whole, and the limiting block 32 abuts against the bottom outer wall of the cylinder 1.

[0055] For example, the positioning rod 3 may be made of high-purity quartz or other high-temperature resistant materials.

[0056] It should be noted that by replacing different positioning rods 3, the extension length of the long arm of the L-shaped rod 31 can be adjusted, thereby accurately setting the distance from the lower edge of the guide tube to the liquid surface; and if the ends of all the long arms are in contact with the liquid surface at the same time, it proves that the thermal field is level. If there is a height difference, it indicates that the assembly is tilted and needs to be adjusted in time, which ensures the accuracy of levelness monitoring.

[0057] It should be noted that the cooperation between the limiting block 32 and the socket 102 ensures that the positioning rod 3 remains stable under high temperature and vibration environments, preventing calibration failure. Furthermore, the positioning rod 3 can be easily and quickly installed and replaced manually, shortening equipment debugging time.

[0058] The design of the aforementioned positioning rod 3 enables precise calibration, horizontal alignment, and rapid assembly and disassembly, significantly improving the stability and controllability of the process and possessing high engineering application value.

[0059] Based on the above embodiments, such as Figures 1-3 and Figure 4 As shown, it also includes:

[0060] The flow guide ring 4 is coaxially fixed to the bottom end of the cylinder 1, and the inner diameter of the flow guide ring 4 is smaller than the inner diameter of the bottom opening of the hollow channel 101.

[0061] By setting the flow guide ring 4, the direct impact of the airflow on the liquid surface is reduced, ensuring the stability of the crystal-melt interface; it also guides the airflow to diffuse radially outward along the liquid surface, thereby effectively removing impurities such as silicon oxide (SiO) volatilized from the melt surface, preventing impurities from accumulating at the crystal-melt interface, thus improving crystal purity.

[0062] In this embodiment, as Figure 2 and Figure 3 As shown, the inner circumferential wall of the guide ring 4 has multiple notches 401. The notches 401 match the long arm of the L-shaped rod 31 to ensure that the long arm can be stably embedded. The width of the notch 401 is slightly larger than the diameter of the long arm of the L-shaped rod 31 to allow for thermal expansion gaps while avoiding excessive shaking.

[0063] By setting the notch 401, the long arm of the L-shaped rod 31 can be radially constrained, thus forming a three-dimensional fixation together with the axial limit of the limiting block 32, thereby enhancing the stability of the positioning rod 3.

[0064] In this embodiment, as Figure 2 and Figure 3 As shown, the outer circumference of the guide ring 4 extends upward to form a gradually expanding neck 402. The inner circumferential surface of the gradually expanding neck 402 is fitted and fixed to the outer circumferential surface of the bottom end of the cylinder 1. The gradually expanding neck 402 is preferably a frustum conical structure and is connected by rivets.

[0065] It should be noted that the expanding neck 402 is an upward sleeve structure that fits onto the outside of the bottom end of the cylinder 1. Therefore, when the airflow flows from top to bottom, it will not encounter an inwardly contracting step at this connection, thereby reducing the local resistance of the airflow through this connection and maintaining the stability of the flow field.

[0066] By setting the gradually expanding neck 402, the contact area between the cylinder 1 and the guide ring 4 is increased, which can effectively disperse stress and prevent loosening or cracking at the connection. The tight fit between the two ensures the sealing of the connection. Furthermore, the use of the conical surface fit forms a mechanical interlock to achieve axial limiting, which increases the connection stability of the guide ring 4 and also ensures the stability of the flow field.

[0067] In some embodiments, such as Figure 2 As shown, the cylinder 1 includes an upper conical cylinder 11, a middle straight cylinder 12 and a lower conical cylinder 13 connected sequentially from top to bottom, and the cross-sections of the upper conical cylinder 11 and the lower conical cylinder 13 gradually shrink from top to bottom.

[0068] It should be noted that the upper conical section 11 can guide the argon gas to accelerate along the conical surface, thereby reducing the residence time of the gas flow at the top of the cylinder 1 and reducing the risk of impurity deposition; the constant diameter region of the middle straight cylinder section 12 provides a uniform gas flow environment for crystal growth, avoiding turbulence or eddies caused by diameter changes; the tapered structure of the lower conical section 13 increases the flow velocity of the gas flow when it approaches the melt, thereby enhancing the ability to carry volatiles on the surface of the melt.

[0069] The above structural design of cylinder 1 can guide the airflow direction and optimize the airflow field, thereby improving the crystal quality, process stability and equipment reliability of CZ silicon single crystal growth.

[0070] Based on the above embodiments, such as Figure 1 As shown, the outer wall of the top end of the upper conical cylinder 11 extends radially outward to form a flange 1101, and the top surface of the flange 1101 is attached and fixed to the bottom surface of the support ring 2.

[0071] By setting the flange 1101, a large-area surface contact is achieved between the upper conical cylinder 11 and the support ring 2, which significantly increases the connection stiffness, reduces stress concentration, improves the load-bearing capacity, and prevents the connection from loosening or falling off.

[0072] Based on the above embodiments, such as Figure 1 As shown, the bottom end of the upper conical section 11 extends axially downward to form a straight neck 1102, and the outer peripheral surface of the straight neck 1102 is fitted and fixed to the inner peripheral surface of the top end of the middle straight section 12.

[0073] It should be noted that the straight neck 1102 is inserted downward into the interior of the top of the straight cylinder 12 to form a sleeve structure. Therefore, when the airflow passes through the hollow channel 101 from top to bottom, it will not encounter an inwardly contracting step at the connection, thereby reducing the local resistance of the airflow through the connection and maintaining the stability of the flow field.

[0074] By setting the straight neck 1102 to be fitted and fixed with the middle straight cylinder 12 over a large area, the connection performance (rigidity, strength, resistance to stress concentration, and prevention of loosening) is significantly improved by utilizing the increased contact area. At the same time, the cone structure of the upper cone cylinder 11 is used to achieve axial limiting and ensure the stability of the flow field.

[0075] Based on the above embodiments, such as Figure 1 As shown, the bottom end of the straight cylindrical portion 12 extends axially downward to form a tapered neck 1201, and the outer peripheral surface of the tapered neck 1201 is fitted and fixed to the inner peripheral surface of the top end of the lower conical portion 13.

[0076] It should be noted that the tapered neck 1201 is a sleeve structure formed by inserting downward into the top of the lower conical part 13. Therefore, when the airflow passes through the hollow channel 101 from top to bottom, it will not encounter an inwardly constricted step at the connection, thereby reducing the local resistance of the airflow through the connection and maintaining the stability of the flow field.

[0077] By setting the tapered neck 1201, the contact area between the middle straight cylinder 12 and the lower conical cylinder 13 is increased, which can effectively disperse stress, prevent loosening or cracking at the connection, and ensure the sealing of the connection through the tight fit between the two. Furthermore, the use of the conical surface to form a mechanical interlock achieves axial limiting, increases the stability of the connection, and also ensures the stability of the flow field.

[0078] In some embodiments, such as Figure 1 and Figure 4 As shown, the support ring 2 has an observation hole 201, which provides an in-situ observation window for the state of the quartz crucible.

[0079] The above settings allow operators to check the status of the quartz crucible through the observation hole 201 during the crystal growth process, thereby enabling them to promptly identify safety risks in the production process.

[0080] Further explanation regarding this application:

[0081] The guide tube uses the bottom end of the positioning rod 3 as the calibration reference. The length of the positioning rod extending beyond the bottom end of the tube body 1 (which can be preset) directly indicates the theoretical distance from the lower edge of the guide tube to the silicon liquid surface. In actual operation, quantitative control can be achieved by observing the contact state between the bottom end of the positioning rod 3 and the liquid surface (such as whether it is immersed in the melt). The circumferentially evenly distributed positioning rods 3 form a multi-reference point plane. If the bottom ends of all positioning rods 3 simultaneously contact the same plane (such as the liquid surface) during assembly, the overall levelness of the thermal field can be verified. The detachable connection between the positioning rod 3 and the tube body 1 allows the equipment to replace positioning rods 3 of different lengths according to different process requirements (such as different diameter crystals and different temperature gradient requirements), thus improving the versatility of the equipment.

[0082] Numerous specific details are set forth in this specification. However, it will be understood that embodiments of this invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0083] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model, and they should all be covered within the scope of the claims and specification of this utility model.

Claims

1. A convection tube for growing a silicon single crystal, characterized by comprising: a convection tube body having a cylindrical shape, and a plurality of grooves formed on an inner surface of the convection tube body. include: The cylindrical body has an axially continuous hollow channel; A support ring is coaxially fixedly connected to the top end of the cylinder, and the inner diameter of the support ring matches the inner diameter of the top opening of the hollow channel. Multiple positioning rods are evenly distributed circumferentially at the bottom end of the cylinder and are detachably connected to the cylinder, with the bottom end of the positioning rods extending downward beyond the bottom end of the cylinder.

2. The convection current guide for growing a silicon single crystal according to claim 1, wherein The positioning rod includes: L-shaped bar; A limiting block is located at the end of the short arm of the L-shaped rod; The bottom sidewall of the cylinder has multiple insertion holes, through which the L-shaped rod can pass as a whole, and the limiting block abuts against the bottom outer wall of the cylinder.

3. The convection current guide for growing a silicon single crystal according to Claim 2, wherein include: A flow guide ring is coaxially fixedly connected to the bottom end of the cylinder, and the inner diameter of the flow guide ring is smaller than the inner diameter of the bottom opening of the hollow channel.

4. The convection current guide for growing a silicon single crystal according to Claim 3, wherein The inner circumferential wall of the guide ring has multiple notches, which match the long arm of the L-shaped rod.

5. The convection current guide for growing a silicon single crystal according to Claim 3, wherein The outer circumference of the guide ring extends upward to form a gradually expanding neck, and the inner circumferential surface of the gradually expanding neck is fitted and fixed to the outer circumferential surface of the bottom end of the cylinder.

6. The convection moderator according to claim 1, wherein The cylinder body includes an upper conical section, a middle straight section, and a lower conical section connected sequentially from top to bottom, and the cross-sections of the upper conical section and the lower conical section gradually taper from top to bottom.

7. The convection current guide for growing a silicon single crystal according to Claim 5, wherein The outer wall of the top end of the upper conical section extends radially outward to form a flange, and the top surface of the flange is fitted and fixed to the bottom surface of the support ring.

8. The convection current guide for growing a silicon single crystal according to Claim 5, wherein The bottom end of the upper conical section extends axially downward to form a straight neck, and the outer peripheral surface of the straight neck is fitted and fixed to the inner peripheral surface of the top end of the middle straight section.

9. The convection current guide for growing a silicon single crystal according to Claim 5, wherein The bottom end of the straight cylindrical section extends axially downward to form a tapered neck, and the outer peripheral surface of the tapered neck is fitted and fixed to the inner peripheral surface of the top end of the lower conical section.

10. The convection moderator according to Claim 1, wherein An observation hole is provided on the support ring.

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