Cooling screen device and single crystal furnace

Abstract

The present disclosure relates to a cooling screen device and a single crystal furnace, in one aspect, there is provided a cooling screen device, on an inner side of a thermal field guide cylinder of a single crystal furnace, comprising: a cooling screen, the cooling screen being annular and defining therein a chamber for a cooling fluid to flow, the cooling screen comprising an inner peripheral portion, an outer peripheral portion, and a baffle plate, the inner peripheral portion comprising a first inclined surface, the outer peripheral portion comprising a second inclined surface, and the baffle plate comprising a second inclined surface; the first inclined surface is gradually expanded upwards along the axial direction of the cooling screen when the cooling screen device is arranged in the single crystal furnace, and the baffle plate is connected between the inner peripheral part and the outer peripheral part, so that a plurality of first fluid channels are formed in the cavity. Therefore, the growth speed and quality of the crystal bar can be improved.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor manufacturing technology, and more specifically, to cooling screen devices and single crystal furnaces. Background Technology

[0002] The Czochralski method is a common method for manufacturing monocrystalline silicon. In the Czochralski method, polycrystalline silicon raw material is placed in a quartz crucible in a single crystal furnace and heated to melt. A seed crystal is inserted into the molten polycrystalline silicon to fuse with it. Then, by slowly rotating and pulling the seed crystal upward, a monocrystalline silicon rod can be obtained.

[0003] In the process of preparing single-crystal silicon rods by the Czochralski method, the temperature gradient inside the single-crystal furnace needs to be adjusted according to different processes to improve the crystal pulling speed and the quality of the crystal rods.

[0004] However, the temperature gradient distribution within the single crystal furnace is currently not ideal, affecting the quality of the obtained crystals. Furthermore, the suboptimal temperature gradient distribution at the solid-liquid interface during crystal growth leads to a slower crystal growth rate, resulting in lower production efficiency. This also causes the temperature at the edge of the quartz crucible to be insufficiently low, leading to greater oxygen precipitation within the crucible and consequently, a lower oxygen content in the obtained single-crystal silicon rods. Utility Model Content

[0005] This section provides a general overview of this disclosure, rather than a full disclosure of the entire scope or all features of this disclosure.

[0006] The purpose of this disclosure is to provide a cooling screen device that can optimize the temperature gradient distribution within a single crystal furnace.

[0007] To achieve the above objectives, according to one aspect of this disclosure, a cooling screen device is provided for installation inside the hot zone guide tube of a single crystal furnace, the cooling screen device comprising:

[0008] A cooling screen, which is annular in shape and defines a chamber therein for the flow of cooling fluid.

[0009] The cooling screen includes an inner peripheral portion, an outer peripheral portion, and a baffle. The inner peripheral portion includes a first inclined surface, which gradually expands upward along the axial direction of the cooling screen when the cooling screen device is installed in the single crystal furnace. The baffle connects the inner peripheral portion and the outer peripheral portion to form multiple first fluid channels in the chamber.

[0010] In some embodiments, the cooling screen device may further include a fixing rod connected to the cooling screen for fixing the cooling screen, and the fixing rod is hollow to define a second fluid channel communicating with the first fluid channel therein.

[0011] In some embodiments, the cooling screen device may further include a cooling screen lifting mechanism, which may be connected to a fixed rod for raising and lowering the cooling screen.

[0012] In some embodiments, the fixing rod may include a fixing member for fixing the thermal field guide tube thereon so that the cooling screen device is located inside the thermal field guide tube.

[0013] In some embodiments, the cooling screen may include an inlet and an outlet for cooling fluid to enter and exit the chamber, respectively, and the inlet and outlet may both be located on the inner periphery.

[0014] In some embodiments, the outer periphery may include a second inclined surface, which may gradually expand upward along the axial direction of the cooling screen when the cooling screen device is installed inside the single crystal furnace.

[0015] In some implementations, a portion of the inner periphery may be recessed outward along the radial direction of the cooling screen to form a notch.

[0016] In some implementations, the cooling screen can be an integral structure.

[0017] In some embodiments, the outer surface of at least one of the cooling screen and the fixing rod may be provided with a black ceramic coating.

[0018] According to another aspect of this disclosure, a single crystal furnace is also provided, which includes the cooling screen device according to any of the above embodiments.

[0019] According to the above technical solution, by including a first inclined surface on the outer periphery of the cooling screen, which gradually expands upward along the axial direction of the cooling screen when the cooling screen device is installed in the single crystal furnace, the temperature gradient distribution from bottom to top in the axial direction within the single crystal furnace is optimized. That is, the temperature gradient distribution within the thermal field guide tube is optimized, thereby improving the quality of the obtained crystal. Furthermore, the temperature gradient at the solid-liquid interface of the crystal growth is also optimized, allowing the crystal rod to cool faster, accelerating crystal growth, and improving production efficiency. Additionally, the temperature at the edge of the crucible used to hold the polycrystalline silicon raw material within the single crystal furnace is reduced, thereby reducing oxygen evolution within the crucible and thus lowering the oxygen content of the obtained crystal rod, improving crystal quality. Moreover, by setting baffles within the chamber to form multiple first fluid channels, the length of the flow path of the cooling fluid within the chamber is increased, allowing the cooling fluid to flow in the chamber with a longer and more regular flow path, thereby enhancing the cooling effect of the cooling screen device on the crystal rod and further optimizing the temperature gradient in the axial direction within the single crystal furnace. Attached Figure Description

[0020] The features and advantages of embodiments of the present disclosure will become more readily understood from the following description with reference to the accompanying drawings. The drawings are not drawn to scale and some features may be enlarged or reduced to show detail of specific parts. In the drawings:

[0021] Figure 1 This is a schematic perspective view of a cooling screen device according to an embodiment of the present disclosure.

[0022] Figure 2 for Figure 1 A cross-sectional view along line AA of the cooling screen device shown.

[0023] Figure 3 for Figure 1 The top view of the cooling screen device shown.

[0024] Figure 4 This is a schematic perspective view of a cooling screen device according to another embodiment of the present disclosure.

[0025] Figure 5 This is a schematic perspective view of a cooling screen device according to yet another embodiment of the present disclosure.

[0026] Figure 6 for Figure 5 A cross-sectional view along line AA of the cooling screen device shown.

[0027] Figure 7 for Figure 5 The top view of the cooling screen device shown.

[0028] Figure 8 The illustration schematically shows the circulation of cooling fluid within the chamber of the cooling screen device.

[0029] Figure 9 This is a schematic structural diagram of a single crystal furnace according to an embodiment of the present disclosure.

[0030] In the accompanying drawings, the same or corresponding technical features, parts or components are represented by the same or corresponding reference numerals. Detailed Implementation

[0031] The present disclosure will now be described in detail with reference to the accompanying drawings and exemplary embodiments. It should be noted that the following detailed description of the present disclosure is for illustrative purposes only and is not intended to limit the scope of the disclosure.

[0032] It should be noted that, for clarity, not all features of a particular embodiment are described or shown in the specification and drawings. Furthermore, to avoid unnecessary details obscuring the technical solutions of interest in this disclosure, only the device structures and parts closely related to the technical solutions of this disclosure are described and shown in the specification and drawings, while other details that are not closely related to the technical content of this disclosure and are known to those skilled in the art are omitted.

[0033] Typically, in a single-crystal furnace, a thermal flow guide tube is used to guide the heat flow within the thermal field. This tube is positioned above the crucible inside the furnace to control the axial temperature gradient distribution, ensuring that the temperature gradient gradually decreases from bottom to top. However, the temperature gradient distribution obtained using only the thermal flow guide tube is not ideal.

[0034] In this regard, refer to Figures 1 to 9 According to embodiments of this disclosure, a cooling screen device 10 is provided. The cooling screen device 10 is used to be disposed inside the hot zone guide tube 20 of the single crystal furnace 1, such as... Figure 9 As shown in the image.

[0035] The cooling screen device 10 includes a cooling screen 110. The cooling screen 110 is annular and defines a chamber G therein for the flow of cooling fluid 2.

[0036] The cooling fluid 2 can be a liquid with good thermal conductivity, such as water, or a gas with good thermal conductivity, in order to reduce the temperature of the cooling screen 110.

[0037] The cooling screen 110 includes an inner peripheral portion 1110, an outer peripheral portion 1120, and a baffle 1130. The inner peripheral portion 1110 is the part of the annular cooling screen 110 located on its inner peripheral side. Figure 9 In the middle, the crystal rod 3, which passes through the central hole 110a of the annular cooling screen 110 during drawing, is close to it, while the outer peripheral portion 1120 is the part of the annular cooling screen 110 located on its outer peripheral side. Figure 9 In the middle, it is far away from the crystal rod 3 that passes through the central hole 110a of the annular cooling screen 110.

[0038] The inner periphery 1110 includes a first inclined surface 1111, which gradually expands upward along the axial direction of the cooling screen 110 when the cooling screen device 10 is installed inside the single crystal furnace 1.

[0039] In other words, when the cooling screen 110 is in the working position, the radial distance between the first inclined surface 1111 and the central axis of the cooling screen 110 gradually increases from bottom to top along the axial direction of the cooling screen 110, causing the cooling effect of the first inclined surface 1111 of the cooling screen 110 relative to the position of the central axis to gradually decrease from bottom to top.

[0040] Therefore, the cooling effect of the cooling screen 110 in the axial direction changes in the same direction as the temperature gradient in the axial direction inside the single crystal furnace under the action of the heat field guide tube 20 located on its radial outer side.

[0041] In this way, the bottom-up temperature gradient distribution along the axial direction within the single crystal furnace can be optimized, that is, the temperature gradient distribution within the thermal flow guide tube can be optimized, thereby improving the quality of the obtained crystal. Furthermore, by optimizing the temperature gradient distribution within the thermal flow guide tube, the temperature gradient at the solid-liquid interface of crystal growth can also be optimized, allowing the crystal rod to cool faster, accelerating crystal growth, and improving production efficiency. Additionally, the temperature at the edge of the crucible 30 used to hold the polycrystalline silicon raw material 4 within the single crystal furnace 1 can also be reduced, thereby reducing oxygen precipitation within the crucible and thus lowering the oxygen content of the obtained crystal rod, improving crystal quality.

[0042] like Figure 2 and Figure 8 As shown, the baffle 1130 is connected between the inner peripheral portion 1110 and the outer peripheral portion 1120 to form a plurality of first fluid channels 1131 in the chamber G.

[0043] The baffle 1130 can be connected between the inner peripheral portion 1110 and the outer peripheral portion 1120 by means of welding, for example, to extend from the top to the bottom of the chamber G, thereby forming a plurality of first fluid channels 1131 in the chamber G, and thereby defining the flow path and distribution of the cooling fluid 2.

[0044] Various connection methods can be envisioned for the multiple first fluid channels 1131 divided by the baffle 1130. For example, the multiple first fluid channels 1131 can be connected in series, with each first fluid channel 1131 connected end to end in sequence, so that the cooling fluid 2 flows through each first fluid channel 1131 in sequence. It is easy to understand that the multiple first fluid channels 1131 can also be connected in parallel, in a mesh, or other ways.

[0045] By setting baffles 1130 to form multiple first fluid channels 1131, the length of the flow path of the cooling fluid 2 in the chamber G is increased, so that the cooling fluid can flow in the chamber G with a longer and more regular flow path, thereby increasing the contact area between the cooling fluid 2 and the cooling screen 110, and thus enhancing the cooling effect of the cooling screen device 10 on the crystal rod 3, and thus further optimizing the temperature gradient in the axial direction inside the single crystal furnace.

[0046] In some implementations, refer to Figures 4 to 7The cooling screen device 10 may also include a fixing rod 120, which is connected to the cooling screen 110 for fixing the cooling screen 110, and the fixing rod 120 is hollow to define a second fluid channel 121 communicating with the first fluid channel 1131.

[0047] In this way, the cooling screen 110 can be fixed by the fixing rod 120, thereby avoiding poor cooling effect on the crystal rod 3 due to factors such as shaking of the cooling screen 110. On the other hand, the cooling fluid 2 that has absorbed heat and heated up in the chamber G can be discharged through the second fluid channel 121, and at the same time, low-temperature cooling fluid 2 can be replenished into the chamber G. That is to say, the supply and discharge of cooling fluid 2 are carried out through the second fluid channel 121 so that the heat of the cooling screen 110 can be continuously and smoothly absorbed and carried away by the cooling fluid 2.

[0048] It is conceivable that the cooling screen 110 can be fixed to the furnace cover of the single crystal furnace via the fixing rod 120. However, it is also conceivable that the cooling screen 110 can be fixed to other parts of the single crystal furnace via the fixing rod 120.

[0049] In some implementations, refer to Figure 9 The cooling screen device 10 may also include a cooling screen lifting mechanism 130, which is connected to a fixed rod 120 for lifting the cooling screen 110.

[0050] In this case, the cooling screen lifting mechanism 130 can lift the cooling screen 110, which is fixedly connected to the fixed rod 120, by driving the fixed rod 120 to lift.

[0051] In this way, the height of the cooling screen 110 can be adjusted so that the cooling screen 110 can be placed in the desired position, thereby optimizing the temperature gradient distribution at the desired position.

[0052] The cooling screen lifting mechanism 130 can be located outside the furnace cover of the single crystal furnace so as not to affect the thermal environment inside the single crystal furnace. However, other installation positions of the cooling screen lifting mechanism 130 are also conceivable and are not limited here.

[0053] In some implementations, refer to Figure 5 and Figure 6 The fixing rod 120 may include a fixing member 122 for fixing the thermal field guide tube 20 thereon so that the cooling screen device 10 is located inside the thermal field guide tube 20.

[0054] In this configuration, the thermal guide tube 20 can be synchronously raised and lowered by the lifting and lowering of the cooling screen device 10. This avoids frequent changes in the positional relationship between the cooling screen device 10 and the thermal guide tube 20 during the crystal pulling process, thereby making the temperature gradient distribution inside the thermal guide tube 20 more stable and helping to maintain the stability of the quality of the obtained crystal.

[0055] In some implementations, refer to Figures 1 to 8 The cooling screen 110 may include an inlet 1112 and an outlet 1113 for the cooling fluid 2 to enter and exit the chamber G respectively, and both the inlet 1112 and the outlet 1113 are provided on the inner periphery 1110.

[0056] Specifically, inlet 1112 is used to allow cooling fluid 2 to enter chamber G, so that the cooling fluid 2 in chamber G can absorb heat conducted from the inner peripheral portion 1110 and the outer peripheral portion 1120. Outlet 1113 is used to allow cooling fluid 2 to leave chamber G. The cooling fluid 2 that has absorbed heat and heated up in chamber G can be discharged from outlet 1113, thereby facilitating the recycling of cooling fluid 2, for example, after cooling.

[0057] In this way, the cooling fluid 2 enters from the inlet 1112, flows through the chamber G and absorbs heat, and then flows out from the outlet 1113. Thus, the heat of the cooling screen 110 can be continuously and smoothly absorbed and carried away by the cooling fluid 2.

[0058] In addition, both the inlet 1112 and the outlet 1113 are located at the inner circumference 1110. On the one hand, this facilitates the connection between the liquid inlet pipe and the liquid outlet pipe (e.g., the fixing rod) and the inlet 1112 and the outlet 1113 without taking up too much space. On the other hand, it enables the cooling fluid 2 to enter and exit the chamber G more smoothly, thereby improving the cooling efficiency.

[0059] like Figure 1 As shown, the number of inlets 1112 and outlets 1113 can both be one. However, it is conceivable that the number of inlets 1112 and outlets 1113 can also be multiple, thereby allowing the cooling fluid 2 in the chamber G to obtain a more complex flow path to meet cooling requirements such as zoned cooling.

[0060] In some implementations, refer to Figure 1 , Figure 2 , Figure 4 , Figure 5 and Figure 6 The outer periphery 1120 may include a second inclined surface 1121, which gradually expands upward along the axial direction of the cooling screen 110 when the cooling screen device 10 is installed inside the single crystal furnace 1.

[0061] The inclined surface 201 of the heat field guide tube 20 also gradually expands upward in the axial direction. In this case, by including a second inclined surface 1121 that gradually expands upward in the axial direction in the outer periphery 1120 of the cooling screen 110, the cooling screen 110 can be arranged inside the inclined surface 201 of the heat field guide tube 20 during operation. Since the temperature gradient distribution provided by the heat field guide tube 20 at the inclined surface 201 is relatively optimal, arranging the cooling screen 110 inside the inclined surface 201 can further optimize the already relatively optimal temperature gradient distribution, thereby obtaining a more optimized temperature gradient distribution effect.

[0062] In some implementations, refer to Figure 4 , Figure 5 , Figure 7 and Figure 8 A portion of the inner circumference 1110 may be recessed outward along the radial direction of the cooling screen 110 to form a notch 1114.

[0063] As mentioned above, the crystal rod 3 is surrounded by an annular cooling screen 110 for cooling. In order to achieve better cooling effect of the cooling screen device 10 and thus obtain a better temperature gradient distribution, under the premise of ensuring production safety, the inner periphery 1110 of the cooling screen 110 is generally made as close as possible to the crystal rod 3.

[0064] However, the top of the single crystal furnace 1 is usually equipped with a camera for observing the growth of the crystal rods inside the furnace, such as detecting the diameter of the crystal rods. When the distance between the crystal rod 3 and the inner periphery 1110 of the cooling screen 110 is small, the inner periphery 1110 of the cooling screen 110 may block the camera's field of view, hindering the observation of the growth of the crystal rods inside the single crystal furnace 1.

[0065] By recessing a portion of the inner periphery 1110 outward along the radial direction of the cooling screen 110 to form a notch 1114, the growth status of the crystal rod inside the single crystal furnace 1 can be observed through the notch 1114. Thus, while the cooling screen 110 is close to the crystal rod for cooling, a clear observation of the growth status of the crystal rod inside the furnace can still be achieved.

[0066] In some implementations, the cooling screen 110 can be an integral structure.

[0067] For example, the inner peripheral portion 1110, the outer peripheral portion 1120 and the baffle 1130 can be integrally formed, or the inner peripheral portion 1110, the outer peripheral portion 1120 and the baffle 1130 can be formed into an integral structure by welding or other means.

[0068] In some embodiments, the outer surface of at least one of the cooling screen 110 and the fixing rod 120 may be provided with a black ceramic coating.

[0069] In this way, the heat absorption capacity of the cooling screen 110 and the fixing rod 120 can be enhanced, and metal ions can be prevented from precipitating from the cooling screen 110 and the fixing rod 120 and contaminating the crystal rod 3 under the high temperature environment in the single crystal furnace 1.

[0070] According to another aspect of this disclosure, referring to Figure 9 Furthermore, a single crystal furnace 1 was proposed, which includes a cooling screen device 10.

[0071] While this disclosure has been described with reference to exemplary embodiments, it should be understood that this disclosure is not limited to the specific embodiments described and shown herein. Various changes to the exemplary embodiments can be made by those skilled in the art without departing from the scope defined by the claims of this disclosure.

[0072] The features mentioned and / or shown in the foregoing description of exemplary embodiments of this disclosure may be combined in the same or similar manner with one or more other embodiments, combined with features in other embodiments, or substituted for corresponding features in other embodiments. Such combinations or substitutions should also be considered as including within the scope of protection of this disclosure.

Claims

1. A cooling shield device for being disposed on the inner side of a hot zone draft tube of a single crystal furnace, characterized by, The cooling screen comprises an inner circumferential portion, an outer circumferential portion and a baffle plate, The inner circumferential portion comprises a first slope which is divergent upward along an axial direction of the cooling screen when the cooling screen device is arranged in the single crystal furnace, and the baffle plate is connected between the inner circumferential portion and the outer circumferential portion to form a plurality of first fluid passages in the chamber.

2. The cooling screen device of claim 1, wherein, The fixing rod is hollow to define a second fluid passage therein which is in communication with the first fluid passages.

3. The cooling screen device of claim 2, wherein, The cooling screen lifting mechanism is connected with the fixing rod for lifting the cooling screen.

4. The cooling screen device of claim 2, wherein, The fixing rod comprises a fixing member for fixing the thermal field shroud thereon so that the cooling screen device is located inside the thermal field shroud.

5. The cooling screen device of claim 1, wherein, The cooling screen comprises an inlet and an outlet for cooling fluid to enter and exit the chamber respectively, and the inlet and the outlet are arranged at the inner circumferential portion.

6. The cooling screen device of claim 1, wherein, The outer circumferential portion comprises a second slope which is divergent upward along an axial direction of the cooling screen when the cooling screen device is arranged in the single crystal furnace.

7. The cooling screen device of claim 1, wherein, A portion of the inner circumferential portion is concave outward along a radial direction of the cooling screen to form a notch.

8. The cooling screen device of claim 1, wherein, The cooling screen is of an integrated structure.

9. The cooling screen device of claim 2, wherein, An outer surface of at least one of the cooling screen and the fixing rod is provided with a black ceramic coating.

10. A single crystal furnace characterized by comprising: The cooling screen device according to any one of claims 1 to 9.

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