Guide cylinder and single crystal furnace

Abstract

The utility model discloses a guide cylinder and a single crystal furnace. The guide cylinder comprises a cylinder body, an annular base plate and a through hole. The cylinder body comprises a first port and a second port which are oppositely arranged, the annular base plate covers the first port of the cylinder body and comprises an annular body, the annular body and the cylinder body are arranged along the same central axis, the annular body comprises an outer circumferential surface and an inner circumferential surface, the inner circumferential surface of the annular base plate forms an inner side wall, and the outer circumferential surface of the annular base plate forms an outer side wall; the outer circumferential surface of the annular chassis forms an outer side wall. The through hole comprises an air inlet formed in the inner side wall of the annular base plate and an air outlet formed in the outer side wall of the annular base plate, the through hole penetrates through the annular base plate in the direction from the inner side wall to the outer side wall of the annular base plate, and the cross section of the air inlet is larger than that of the air outlet. The through hole is formed in the guide cylinder, and the air inlet is larger than the air outlet, so that the temperature gradient of a crystal bar interface is stable, and the flow speed of fluid is changed under the condition that the furnace pressure is not changed to control the crystal oxygen content.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductor manufacturing, in particular to a guide tube and a single crystal furnace. Background Art

[0002] Single crystal production is primarily based on the Czochralski method. Controlling oxygen during the Czochralski process is crucial for ultra-large-scale integrated circuit (VLSI) equipment and wafer manufacturing. Various techniques have been developed to control oxygen concentration in silicon crystals produced using the Czochralski method, including seed rotation control, crucible rotation control, crucible position control, furnace pressure control, and the application of various magnetic fields.

[0003] Controlling the argon flow rate can effectively control the oxygen content in silicon crystals grown by the Czochralski method. As the argon gas sweeps across the surface of the silicon melt, it causes a temperature drop and also acts on the surface through shear stress, altering the melt's flow pattern. Increasing the flow rate can alter the melt's flow through shear stress, thereby affecting the silicon monoxide evaporation area and the oxygen concentration in the crystal.

[0004] The Czochralski method for producing single crystals takes place in a single crystal furnace. This furnace is equipped with a draft tube. However, existing draft tubes are unable to stabilize the temperature gradient at the ingot interface and control the oxygen content of the crystal by varying the melt flow rate without changing the furnace pressure. Utility Model Content

[0005] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a guide tube and a single crystal furnace, which can change the flow rate of the melt surface fluid without changing the furnace pressure to control the oxygen content of the crystal.

[0006] In order to achieve the above-mentioned and other related purposes, the present invention provides a guide tube, comprising:

[0007] The cylinder comprises a first port and a second port which are arranged opposite to each other;

[0008] an annular base, which covers the first port of the cylinder, and includes an annular body, which is arranged along the same central axis as the cylinder, and the annular body includes an outer circumferential surface and an inner circumferential surface, the inner circumferential surface of the annular base forms an inner sidewall, and the outer circumferential surface of the annular base forms an outer sidewall;

[0009] At least one through hole, each through hole includes an air inlet formed on the inner wall of the annular chassis and an air outlet formed on the outer wall of the annular chassis, the through hole passes through the annular chassis in a direction from the inner wall to the outer wall of the annular chassis, and the cross-section of the air inlet is larger than the cross-section of the air outlet.

[0010] Optionally, the annular chassis includes a first surface and a second surface arranged opposite to each other, the first surface of the annular chassis is located inside the cylinder, and the second surface of the annular chassis is located outside the cylinder, forming the bottom surface of the guide cylinder, and the through hole includes a horizontal profile parallel to the second surface of the annular chassis and a convex profile protruding relative to the horizontal profile toward the second port of the cylinder.

[0011] Optionally, the cross section of the protruding wall is semicircular.

[0012] Optionally, the cross-sectional area of ​​the through hole gradually decreases along the direction from the air inlet to the air outlet.

[0013] Optionally, along the direction from the air inlet to the air outlet, the cross-sectional area of ​​the through hole first decreases and then increases.

[0014] Optionally, the guide tube includes a plurality of through holes, and the through holes are arranged at intervals along the annular base plate, and the intervals between two adjacent through holes are equal.

[0015] Optionally, the guide tube includes six through holes.

[0016] Optionally, the cross-sectional area of ​​the cylinder gradually increases from the first port to the second port.

[0017] Optionally, the wall thickness of the cylinder gradually decreases from the first port to the second port.

[0018] The utility model also provides a single crystal furnace, comprising the above-mentioned guide tube.

[0019] Compared with the prior art, the guide tube of the present invention has at least the following beneficial effects:

[0020] The guide tube of the present invention includes a cylinder, an annular base and a through hole. The cylinder includes a first port and a second port arranged opposite to each other. The annular base covers the first port of the cylinder. The annular base includes an annular body. The annular body and the cylinder are arranged along the same central axis. The annular body includes an outer circumferential surface and an inner circumferential surface. The inner circumferential surface of the annular base forms an inner side wall, and the outer circumferential surface of the annular base forms an outer side wall. The through hole includes an air inlet formed on the inner side wall of the annular base and an air outlet formed on the outer side wall of the annular base. The through hole passes through the annular base in the direction from the inner side wall to the outer side wall of the annular base, and the cross section of the air inlet is larger than the cross section of the air outlet. The utility model diverts the protective gas by providing a through hole. The cross section of the air inlet of the through hole is larger than the cross section of the air outlet, ensuring that the flow velocity near the liquid surface is reduced without changing the overall flow rate, thereby increasing the oxygen content in the crystal rod. At the same time, through holes are set in the annular chassis to divert the protective gas. The bottom structure of the guide tube remains unchanged. The internal opening reduces the direct heat radiation of the melt and crucible to the crystal rod, making the temperature gradient stable.

[0021] The single crystal furnace of the present invention includes the above-mentioned guide tube and also has the above-mentioned technical effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the guide tube structure described in an embodiment of the present utility model;

[0023] Figure 2 This is a cross-sectional view of the guide tube structure in an embodiment of the present utility model;

[0024] Figure 3 This is a schematic structural diagram of a single crystal furnace in an embodiment of the present utility model;

[0025] Figure 4 for Figure 3 Comparison of fluid flow velocities in area A of the single crystal furnace with and without through holes at the bottom of the middle guide tube.

[0026] List of reference numerals:

[0027] 1 guide tube

[0028] 11 through holes

[0029] 12 Ring chassis

[0030] 121 Ring body

[0031] 111 Air Inlet

[0032] 112 air outlet

[0033] 113 Contour

[0034] 114 horizontal profile

[0035] 13 cylinder

[0036] 131 First Port

[0037] 132 Second Port

[0038] 2 crystal rods

[0039] 3 Crucible DETAILED DESCRIPTION

[0040] The following describes the implementation of the present invention using specific embodiments. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different perspectives and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features within these embodiments may be combined with one another, unless they conflict.

[0041] It should be noted that the diagrams provided in the embodiments of the present invention are only schematic illustrations of the basic concept of the present invention. Although the diagrams only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation, the form, quantity and proportion of each component in actual implementation can be changed at will, and the layout of the components may also be more complex. The structures, proportions, sizes, etc. illustrated in the drawings of the specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions for the implementation of this application. Therefore, they have no technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed in this application without affecting the efficacy and purpose of the present invention.

[0042] To address the problems of the prior art and the aforementioned technical issues, this embodiment provides a flow guide tube and single crystal furnace. These tubes and furnaces can reduce the flow velocity near the liquid surface without changing the overall flow rate, thereby increasing the oxygen content in the crystal ingot. Furthermore, the internal opening reduces direct heat radiation from the melt and crucible to the crystal ingot, stabilizing the temperature gradient.

[0043] The present invention will be described in detail below with reference to specific embodiments.

[0044] Example 1

[0045] This embodiment provides a guide tube, referring to Figure 1 or Figure 2 The guide tube 1 includes a cylinder body 13, an annular base plate 12 and a through hole 11.

[0046] Specifically, refer to Figure 2 The cylinder 13 includes a first port 131 and a second port 132 disposed opposite each other. The cross-sectional area of ​​the cylinder 13 gradually increases from the first port 131 to the second port 132. The guide tube 1 has a truncated cone-shaped structure that is narrow at the bottom and wide at the top. The wall thickness of the cylinder 13 gradually decreases from the first port 131 to the second port 132.

[0047] The annular chassis 12 is covered with the first port 131 of the cylinder 13. The annular chassis 12 includes an annular body 121. The annular body 121 and the cylinder 13 are arranged along the same central axis. The annular body 121 includes an outer circumferential surface and an inner circumferential surface. The inner circumferential surface of the annular chassis 12 is formed as an inner side wall, and the outer circumferential surface of the annular chassis 12 is formed as an outer side wall. The annular chassis 12 includes a first surface and a second surface that are oppositely arranged. The first surface of the annular chassis 12 is located inside the cylinder 13, and the second surface of the annular chassis 12 is located outside the cylinder 13, forming the bottom surface of the guide tube 1.

[0048] The through hole 11 includes an air inlet 111 formed on the inner side wall and an air outlet 112 formed on the outer side wall. The through hole 11 extends through the annular base 12 from the inner side wall to the outer side wall of the annular base 12. The cross-section of the air inlet 111 is larger than the cross-section of the air outlet 112. According to Bernoulli's equation, the smaller the cross-sectional area of ​​the through hole 11, the greater the fluid flow rate and the lower the corresponding pressure. The cross-sectional area of ​​the air inlet 111 is larger than that of the air outlet 112, which can effectively reduce the outlet pressure, prevent backflow while diverting large flows, and change the flow rate of the fluid at the melt surface, thereby controlling the oxygen content of the crystal. Argon is often used as a shielding gas in the Czochralski method to prevent the silicon melt from reacting with oxygen or other impurities in the air during the pulling process. By precisely controlling the flow rate of argon, its behavior on the surface of the silicon melt can be fine-tuned, thereby affecting the physical and chemical state of the melt. The flow of argon will produce shear stress on the melt. Shear stress is an important concept in fluid dynamics, which refers to the force generated by the velocity difference between different layers in the fluid. As the flow rate of argon increases, its shear stress on the melt will also increase, thereby changing the flow pattern of the melt. This change in flow pattern may affect the convection and diffusion processes in the silicon melt, especially the reaction and transmission processes related to oxygen. In the vertical pulling method, the flow of argon will change the flow pattern of the melt, that is, the flow direction and velocity distribution of the melt. The protective gas is diverted by providing a through hole 11, and the cross-section of the air inlet 111 of the through hole is larger than the cross-section of the air outlet 112, thereby ensuring that the melt liquid surface fluid flow rate is changed to control the oxygen content of the crystal without changing the furnace pressure.

[0049] The number of through holes 11 is at least one, and the through hole 11 includes a horizontal profile 114 parallel to the second surface of the annular chassis 12 and a protruding profile 113 protruding relative to the horizontal profile 114 in the direction of the second port 132 of the cylinder 13. During the smelting process, especially when it comes to crystal growth, the stability of the temperature gradient is crucial to the quality of the crystal. The temperature gradient refers to the temperature difference at different positions in the melt. If the temperature gradient is unstable, it may cause defects or impurities during the crystal growth process, thereby affecting the overall performance of the crystal. In this embodiment, the through hole is arranged inside the annular chassis. The internal opening reduces the direct heat radiation of the melt and crucible to the crystal rod, thereby stabilizing the temperature gradient. In addition, the second surface of the annular chassis is still a horizontal bottom surface, which does not bring about structural changes and also ensures the stability of the temperature gradient.

[0050] Optionally, the number of through holes on the annular chassis can be one or more, and setting multiple through holes is more conducive to the diversion of the protective gas. Figure 1 and Figure 2The guide tube 1 includes a plurality of through holes 11, which are spaced circumferentially around the annular base 12, with adjacent through holes 11 spaced evenly apart. The cross-section of the through holes 11 is semicircular. The cross-sectional area of ​​the through holes 11 gradually decreases from the air inlet 111 to the air outlet 112. This may be done by first decreasing and then increasing, or other variations are possible. It should be noted that this embodiment does not restrict the size or variation of other cross-sectional areas of the through holes, as long as the cross-sectional area of ​​the air inlet is greater than that of the air outlet.

[0051] In this embodiment, along the direction from the air inlet 111 to the air outlet 112 , the cross-sectional area of ​​the through hole 11 first decreases and then increases, and the number of the through holes is 6.

[0052] Example 2

[0053] This embodiment provides a single crystal furnace, referring to Figure 1 、 Figure 2 and Figure 3 The single crystal furnace includes the one in Example 1. Figure 1 、 Figure 2 The guide tube 1 shown in FIG. Similarly, the guide tube 1 of the single crystal furnace includes at least one through-hole 11. Each through-hole 11 includes an air inlet 111 formed on the inner sidewall and an air outlet 112 formed on the outer sidewall. The through-hole 11 extends through the annular base 12 from the inner sidewall to the outer sidewall. The cross-section of the air inlet 111 is larger than that of the air outlet 112. The larger cross-section of the air inlet 111 than the air outlet 112 effectively reduces the outlet pressure, diverting large flows while preventing backflow. The provision of the through-hole 11 diverts the shielding gas flow. The cross-section of the air inlet 111 is larger than that of the air outlet 112, ensuring that the melt surface fluid flow rate can be adjusted to control the crystal oxygen content without changing the furnace pressure. The through-hole 11 includes a horizontal profile 114 parallel to the second surface of the annular base 12 and a protruding profile 113 that protrudes relative to the horizontal profile 114 toward the second port 132 of the cylinder 13. The internal opening is adopted so that the bottom structure of the guide tube 1 remains unchanged, reducing the direct heat radiation of the melt and the crucible 3 to the crystal rod 2 and stabilizing the interface temperature gradient of the crystal rod 2.

[0054] The fluid velocity and speed at area A in the single crystal furnace are tested. Figure 4 The middle curve a is Figure 3 The fluid flow velocity at the single crystal furnace area A where no through hole 11 is provided at the bottom of the middle guide tube 1, curve b is an embodiment of the present utility model. Figure 3 The fluid flow velocity at the single crystal furnace area A where the through hole 11 is provided at the bottom of the middle guide tube 1. Figure 4 ,use Figure 1 and Figure 2In the proposed solution, after providing through-holes 11 at the bottom of flow guide tube 1, the velocity above the liquid surface decreased significantly by approximately 20%. Temperature testing also revealed no significant change in the interface temperature gradient. During Czochralski silicon single crystal growth in a horizontal magnetic field, the oxygen concentration in the crystal increases as the flow rate near the interface decreases. This allows for effective control of the oxygen content in the crystal while minimizing disturbances to the solid-liquid interface.

[0055] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed in the present invention are intended to be covered by the claims of the present invention.

Claims

1. A guide tube, characterized in that: include: The cylinder comprises a first port and a second port which are arranged opposite to each other; an annular base, covering the first port of the cylinder, the annular base comprising an annular body, the annular body being arranged along the same central axis as the cylinder, the annular body comprising an outer circumferential surface and an inner circumferential surface, the inner circumferential surface of the annular base forming an inner sidewall, and the outer circumferential surface of the annular base forming an outer sidewall; At least one through hole, each of the through holes includes an air inlet formed on the inner wall of the annular chassis and an air outlet formed on the outer wall of the annular chassis, the through hole passes through the annular chassis in a direction from the inner wall to the outer wall of the annular chassis, and the cross-section of the air inlet is larger than the cross-section of the air outlet.

2. The guide tube according to claim 1, characterized in that: The annular chassis includes a first surface and a second surface arranged opposite to each other, the first surface of the annular chassis is located inside the cylinder, and the second surface of the annular chassis is located outside the cylinder, forming the bottom surface of the guide cylinder, and the through hole includes a horizontal profile parallel to the second surface of the annular chassis and a convex profile protruding relative to the horizontal profile toward the second port of the cylinder.

3. The guide tube according to claim 2, characterized in that: The cross section of the convex profile is semicircular.

4. The guide tube according to claim 1, characterized in that: The cross-sectional area of ​​the through hole gradually decreases along the direction from the air inlet to the air outlet.

5. The guide tube according to claim 1, characterized in that: Along the direction from the air inlet to the air outlet, the cross-sectional area of ​​the through hole first decreases and then increases.

6. The guide tube according to claim 1, characterized in that: The guide tube includes a plurality of through holes, and the through holes are arranged at intervals along the annular bottom plate, and the intervals between two adjacent through holes are equal.

7. The guide tube according to claim 6, characterized in that: The guide tube includes six through holes.

8. The guide tube according to claim 1, characterized in that: The cross-sectional area of ​​the cylinder gradually increases from the first port to the second port.

9. The guide tube according to claim 1, characterized in that: The wall thickness of the cylinder gradually decreases from the first port to the second port.

10. A single crystal furnace, characterized in that: The invention comprises the guide tube according to any one of claims 1 to 9.

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