Heater and single crystal furnace

Abstract

The utility model provides a heater and a single crystal furnace. The abnormal cracking phenomenon of the heater can be improved. The heater comprises an annular heating part and a foot plate, one end of the foot plate is connected with the annular heating part, and the other end of the foot plate is used for being connected with a power supply; the annular heating part is provided with a connecting part, the connecting part is connected with one end of the foot plate, and at least one of the foot plate and the connecting part is provided with a notch structure.

Description

Technical Field

[0001] This utility model relates to the field of silicon wafer processing technology, specifically to a heater and a single crystal furnace. Background Technology

[0002] The heaters used in single-crystal furnaces can be made of isostatically pressed graphite. However, the price increases exponentially with the size of the isostatically pressed graphite blank. Therefore, to reduce the amount of blank material used and lower the cost of the heater, spliced ​​heaters are generally used, which consist of a foot plate and a main heating zone spliced ​​together. However, this type of heater is prone to cracks and localized corrosion at the foot plate and the joint between the foot plate and the main heating zone. Utility Model Content

[0003] The purpose of this application is to provide a heater and a single crystal furnace that can improve the abnormal cracking phenomenon of the heater.

[0004] To solve the above-mentioned technical problems, this application provides a heater, which includes an annular heating part and a foot plate. One end of the foot plate is connected to the annular heating part, and the other end of the foot plate is used to connect to a power source. The annular heating part has a connecting part, which is connected to one end of the foot plate. At least one of the foot plate and the connecting part is provided with a slot structure.

[0005] Optionally, the foot plate is provided with the groove structure, and the groove structure of the foot plate is defined as the first groove structure. The first groove structure is located in the middle of the width direction of the foot plate, and the length direction of the foot plate is the direction from one end of the foot plate and the annular heating part to the other end. The width direction is perpendicular to the length direction.

[0006] Optionally, the first slot structure is a long slot structure extending along the length direction of the foot plate.

[0007] Optionally, the first slot structure extends to both ends of the foot plate, and the first slot structure is offset from the annular heating element.

[0008] Optionally, the connecting portion of the annular heating element is provided with the slot structure, and the slot structure of the connecting portion is defined as a second slot structure, which is offset from the foot plate.

[0009] Optionally, the connecting portion of the annular heating element is provided with a plurality of first connecting holes, and the foot plate is provided with a plurality of second connecting holes. The first connecting holes and the second connecting holes correspond one-to-one, and the connecting portion and the foot plate are connected by fasteners inserted into the corresponding first connecting holes and second connecting holes.

[0010] Optionally, the plurality of first connecting holes of the connecting portion form multiple sets of holes, each set of holes including at least two first connecting holes distributed circumferentially along the annular heating portion, the multiple sets of holes being distributed axially along the annular heating portion, and the hole spacing of different sets of holes being unequal; each set of holes is symmetrically distributed relative to the axial direction of the annular heating portion.

[0011] Optionally, the connecting portion has a first stepped surface and a first stepped sidewall, and the foot plate has a second stepped surface and a second stepped sidewall. The first stepped sidewall of the connecting portion abuts against the second stepped surface, and the second stepped sidewall of the foot plate abuts against the first stepped surface.

[0012] The first connecting hole is disposed on the side wall of the first step, and the second connecting hole is disposed on the side wall of the second step.

[0013] This application also provides a single crystal furnace, including a furnace body and a heater located inside the furnace body, wherein the heater is any of the heaters described above.

[0014] Optionally, the single crystal furnace includes a gas guide pipe disposed at the bottom, and the foot plate of the heater extends toward the bottom of the single crystal furnace.

[0015] In this application, at least one of the heater's foot plate and annular heating element is provided with a slotted structure. Firstly, since both the foot plate and the connecting part are located on the main current inflow and outflow path, the current flow is large and relatively dense, making it prone to ionization with slag powder, volatiles, etc., leading to arcing and generating significant thermal stress due to the large current, thus inducing cracking of the foot plate or connecting part. The slotted structure can divert the current, reducing the current in each branch, lowering the risk of ionization, reducing the temperature difference, and weakening the impact of thermal stress, thereby improving abnormal arcing and cracking. Secondly, because the slotted structure diverts the current, reducing the current intensity, it can also improve localized corrosion at the connection between the annular heating element and the foot plate. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a single crystal furnace in one embodiment of this application.

[0017] Figure 2 for Figure 1 Schematic diagram of the structure of the intermediate heater;

[0018] Figure 3 for Figure 2 Front view of the heater;

[0019] Figure 4 for Figure 3 Left view of the central heater;

[0020] Figure 5 for Figure 4 A magnified view of part A in the middle;

[0021] Figure 6 for Figure 3 Enlarged diagram of part B in the middle.

[0022] The annotations in the attached figures are explained as follows:

[0023] 10-Furnace body;

[0024] 20 - Heater;

[0025] 201-Annular heating element; 2011-Connecting part; 20111-First step sidewall; 20112-First step surface; 2011a-Second slot structure; 2011b-First connecting hole; 2011ba-First hole group; 2011bb-Second hole group; 2012-Second connecting plate; 2013-First connecting plate; 201a-Notch;

[0026] 202-Foot plate; 2021-Foot plate body; 2021a-First groove structure; 20211-Second step sidewall; 20211a-Second connecting hole; 20212-Second step surface; 2022-Connector; 2022a-Hole structure; 203-Fastener;

[0027] 30 - Air guide tube; 30a - Air guide port;

[0028] 40 - Crucible. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a single crystal furnace in one embodiment of this application.

[0031] The single crystal furnace includes a furnace body 10 and a crucible 40 disposed within the furnace body 10. The single crystal furnace also includes a heater 20, which is disposed around the crucible 40 to heat the silicon material located within the crucible 40.

[0032] Please continue to refer to this. Figures 2 to 4 , Figure 2 for Figure 1 Schematic diagram of the structure of the intermediate heater 20; Figure 3 for Figure 2 Front view of the intermediate heater 20; Figure 4 for Figure 3 Left view of the middle heater 20.

[0033] The heater 20 in this embodiment includes an annular heating element 201 and a foot plate 202. The annular heating element 201 is as follows: Figure 2 As shown, it is specifically annular, which can also be defined as a heating ring. The annular heating part 201 surrounds the crucible 40. When energized, the annular heating part 201 can generate heat to heat the crucible 40 from the outside. Figure 2 The main body of the annular heating element 201 is roughly serpentine in shape. That is, the annular heating element 201 includes a plurality of axially extending first connecting plates 2013 and circumferentially extending second connecting plates 2012. The second connecting plates 2012 connect two adjacent first connecting plates 2013. One axial end of each first connecting plate 2013 is connected to a second connecting plate 2012, and the other axial end is connected to another second connecting plate 2012. A notch 201a 201b is formed between two adjacent first connecting plates 2013.

[0034] One end of the foot plate 202 is connected to the annular heating element 201, and the foot plate 202 is used as an electrode of the annular heating element 201. Figure 2 The diagram illustrates two feet 202, which are positioned opposite each other and distributed approximately radially along the annular heating element 201. One foot 202 is used to connect to the negative terminal of the power supply, and the other foot 202 is used to connect to the positive terminal of the foot 202, thereby energizing the annular heating element 201. The annular heating element 201 has a connecting portion 2011, which is a partial structure of the annular heating element 201, such as... Figure 1 As shown, two adjacent second connecting plates 2012 of the annular heating element 201 are connected to a corresponding connecting part 2011. The connecting part 2011 is connected to one end of the foot plate 202 to achieve electrical connection between the foot plate 202 and the annular heating element 201. The two connecting parts 2011 of the annular heating element 201 are also radially distributed, so the annular heating element 201 has a structure of two parallel halves.

[0035] It is worth noting that, in this embodiment, at least one of the foot plate 202 of the heater 20 and the connecting portion 2011 of the annular heating part 201 is provided with a slot structure. The slot structure is a structure that penetrates through the foot plate 202 or the connecting portion 2011 along the thickness direction. Figure 2 In the process, both the foot plate 202 and the connecting part 2011 are provided with a groove structure. The groove structure provided on the foot plate 202 is defined as the first groove structure 2021a, and the groove structure provided on the connecting part 2011 is defined as the second groove structure 2011a.

[0036] The first function of setting the first slot structure 2021a is to reduce abnormal cracking at the foot plate 202 position, and the principle is as follows:

[0037] The annular heating element 201 of the heater 20 is a two-lobed parallel circular structure. A pair of feet 202 are connected to the positive and negative terminals of the power supply, respectively. The feet 202 are positioned on the main current path, where the current flow is at its maximum, for example, reaching approximately 2000-3000 amperes. Due to the characteristic that current flows towards lower resistance, the current on the feet 202 is relatively concentrated, making it prone to ionization with slag powder, volatiles, etc., leading to arcing and potentially causing localized abnormalities in the heater 20. Furthermore, because the current density is high at the center of the feet 202 and low at the edges, thermal stress is generated in the lateral direction of the feet 202. This stress can induce cracking of the feet 202 of the heater 20.

[0038] By designing the first slot structure 2021a on the foot plate 202, the current will start to be shunted directly at the foot plate 202. This reduces the current in each branch, greatly reduces the risk of ionization, and reduces the temperature difference in each branch after shunting. The influence of thermal stress will be weakened, thus improving the abnormal cracking of the foot plate 202.

[0039] Another function of setting the first slot structure 2021a is to reduce local high-temperature corrosion at the connection between the annular heating part 201 and the foot plate 202. The principle is as follows:

[0040] In the foot plate 202 without the first slot structure 2021a, the absolute high-temperature zone connecting the foot plate 202 and the annular heating part 201 is located at the center of the connection point, where the current intensity is the highest. Over time, this leads to the formation of localized corrosion pits. In contrast, the foot plate 202 with the first slot structure 2021a has two relatively high-temperature zones at the connection point between the foot plate 202 and the annular connecting part 2011. However, due to the reduced current intensity, both the temperature and current intensity are significantly lower than in the foot plate 202 without the first slot structure 2021a. This allows for more even current distribution through the connection point, resulting in a substantial improvement in localized corrosion at the connection location.

[0041] It can be seen that the function of setting the second slot structure 2011a is similar to that of the first slot structure 2021a. The second slot structure 2011a divides the connecting part 2011 of the annular heating part 201, which can reduce the concentrated distribution of current in the connecting part 2011 and improve the local corrosion and cracking abnormality of the connecting part 2011.

[0042] To improve localized corrosion and cracking, some related technical solutions employ material replacement, such as using carbon-carbon materials with better toughness to reduce cracking. However, carbon-carbon materials have a large surface roughness and low density, resulting in high costs for densification processes. Furthermore, carbon-carbon heaters have poor resistivity uniformity, making them prone to localized corrosion, which can even exacerbate existing corrosion. In this embodiment, however, improvements in cracking and localized corrosion can be achieved simply by setting a slot structure, at a lower cost. The heater can still be made of isostatically pressed graphite, or other suitable materials can be used.

[0043] like Figure 1 As shown, a gas guide pipe 30 is provided at the bottom of the single crystal furnace. The cavity of the gas guide pipe 30 forms a gas guide hole 30a. Inert gases such as argon that are introduced into the furnace can flow out from the gas guide hole 30a. Volatile substances are more likely to accumulate at the bottom of the furnace body 10. In this embodiment, the foot plate 202 extends to the bottom of the single crystal furnace. The foot plate 202 will be close to the position of the gas guide hole 30a. When the current of the foot plate 202 is large, it is easier to ionize and generate arcing abnormality, causing cracks in the foot plate. The setting of the first slot structure 2021a in this embodiment can better improve the arcing and cracking abnormality.

[0044] Furthermore, the first slot structure 2021a can be located in the middle of the width direction of the foot plate 202, the length direction of the foot plate 202 is the direction from one end of the foot plate 202 and the annular heating part 201 to the other end, the width direction is perpendicular to the length direction, and the width direction is also the transverse direction of the foot plate 202, and the length direction is... Figure 2 The direction of the center is also parallel to the axial direction of the annular heating element 201. As mentioned earlier, the current density is high at the center of the foot plate 202 and low at the edges. By placing the first slot structure 2021a in the middle of the width direction, that is, placing the first slot structure 2021a in the center of the foot plate 202, the current in each branch after being diverted by the first slot structure 2021a is reduced to half of the original, resulting in a more uniform current distribution and better reduction of the impact of thermal stress. Similarly, the second slot structure 2011a can also be located in the middle of the width direction of the connecting part 2011, which is also the circumferential direction of the annular heating element 201.

[0045] like Figure 2 As shown, the first slot structure 2021a on the foot plate 202 is a long slot structure extending along the length direction of the foot plate 202, that is, the dimension of the first slot structure 2021a in the length direction of the foot plate 202 is larger than its dimension in the width direction. Where possible, the first slot structure 2021a is designed to be as long as possible to better shunt current and reduce the number of cracking locations. Of course, the first slot structure 2021a should not be too long. Figure 2In the foot plate 202, the first slot structure 2021a extends to both ends of the foot plate 202, and the first slot structure 2021a is offset from the annular heating part 201 to ensure that the connection part 2011 between the foot plate 202 and the annular heating part 201 has sufficient contact area to ensure connection strength and current path. Similarly, the second slot structure 2011a of the annular heating part 201 is also offset from the foot plate 202.

[0046] In this embodiment, one end of the foot plate 202 is connected to the annular heating element 201, and the other end of the foot plate 202 is used to connect to a power source. Exemplarily, the foot plate 202 includes a foot plate body 2021 and a connector 2022. The foot plate body 2021 extends along its length, and the connector 2022 is connected to the end of the foot plate body 2021. The connector 2022 extends along the thickness direction of the foot plate body 2021. The connector 2022 is provided with a hole structure 2022a, which is used to connect to the positive or negative terminal of the power source. The connector 2022 facilitates electrical connection to the power source.

[0047] Please continue to refer to this. Figure 3 , 4 and combined Figure 5 and Figure 6 understand, Figure 5 for Figure 4 A magnified view of part A in the middle; Figure 6 for Figure 3 Enlarged diagram of part B in the middle.

[0048] In this embodiment, the connecting portion 2011 of the annular heating element 201 is provided with a plurality of first connecting holes 2011b, and the foot plate 202 is provided with a plurality of second connecting holes 20211a. The first connecting holes 2011b and the second connecting holes 20211a correspond one-to-one. The heater 20 also includes fasteners 203. The connecting portion 2011 and the foot plate 202 are connected by fasteners 203 inserted into the corresponding first connecting holes 2011b and second connecting holes 20211a. The fasteners 203 are, for example, fastening pins, fastening screws, etc., and are not limited thereto. The connection using fasteners 203 is simple and reliable, and is a detachable connection, which facilitates maintenance, etc.

[0049] It should be emphasized that, in this embodiment, the multiple first connecting holes 2011b of the connecting portion 2011 are divided into multiple groups of holes, each group including at least two first connecting holes 2011b. The first connecting holes 2011b of each group are distributed circumferentially along the annular heating portion 201, while the multiple groups of holes are distributed axially along the annular heating portion 201. Furthermore, the hole spacing in each group is unequal. Simultaneously, along the axial direction, each group of holes is symmetrically arranged relative to the axial direction of the annular heating portion 201. This symmetrical arrangement results in more uniform force distribution and improves installation reliability.

[0050] In this embodiment, the plurality of first connecting holes 2011b of the connecting portion 2011 are divided into two groups of holes, namely a first group of holes 2011ba and a second group of holes 2011bb. The two groups of holes are distributed vertically. The first group of holes 2011ba includes two first connecting holes 2011b distributed circumferentially along the annular heating portion 201, and the second group of holes 2011bb includes two first connecting holes 2011b distributed circumferentially. The hole spacing of the first group of holes 2011ba and the second group of holes 2011bb is not equal. Figure 6 As can be seen, the hole spacing of the first hole group 2011ba is smaller than the hole spacing of the second hole group 2011bb. Since the second connecting hole 20211a and the first connecting hole 2011b correspond one-to-one, the setting method of the second connecting hole 20211a is the same as that of the first connecting hole 2011b, and will not be discussed again.

[0051] In this embodiment, multiple hole groups are set with unequal hole spacing and are symmetrically arranged relative to the axial direction. This creates a certain angle between adjacent hole groups, resulting in a difference in the center distance between the fasteners 203 inserted in one hole group and the center distance between the fasteners 203 inserted in another adjacent hole group. This reduces the probability of cracks forming between adjacent first connecting holes 2011b in adjacent hole groups. Furthermore, if the radial dimension of the fastener 203 is too small, its strength will be insufficient, leading to inadequate reliability. Conversely, if the radial dimension of the fastener 203 is too large, it will occupy the effective conductive area at the connection position between the connecting part 2011 and the foot plate 202. Therefore, this embodiment specifically uses an M12 screw as the fastener 203 to ensure fastening strength while minimizing the occupation of the effective conductive area at the connection position, thereby increasing the current-carrying area. Furthermore, while the fastener 203 is inserted into the first connecting hole 2011b and the second connecting hole 20211a, an adhesive bonding process can also be used. That is, the foot plate 202 and the connecting part 2011 can be bonded together while simultaneously being secured by the fastener 203. Specific examples of adhesive bonding processes include graphite adhesive bonding.

[0052] Let's look again. Figure 6 In this embodiment, the connecting part 2011 has a first stepped surface 20112 and a first stepped sidewall 20111, and the foot plate 202 has a second stepped surface 20212 and a second stepped sidewall 20211. The first stepped sidewall 20111 of the connecting part 2011 abuts against the second stepped surface 20212, and the second stepped sidewall 20211 of the foot plate 202 abuts against the first stepped surface 20112. That is, the connecting part 2011 and the foot plate 202 are spliced ​​together, resulting in a large conductive contact area and a more reliable connection. Specifically, the first connecting hole 2011b is disposed on the first stepped sidewall 20111, and the second connecting hole 20211a is disposed on the second stepped sidewall 20211.

[0053] This application also provides a single crystal furnace, including the heater 20 described in any of the above embodiments, which has the same technical effects and will not be described again.

[0054] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A heater, characterized in that, The heater (20) includes an annular heating part (201) and a foot plate (202). One end of the foot plate (202) is connected to the annular heating part (201), and the other end of the foot plate (202) is used to connect to a power source. The annular heating part (201) has a connecting part (2011), which is connected to one end of the foot plate (202). At least one of the foot plate (202) and the connecting part (2011) is provided with a slot structure.

2. The heater according to claim 1, characterized in that, The foot plate (202) is provided with the groove structure. The groove structure of the foot plate (202) is defined as the first groove structure (2021a). The first groove structure (2021a) is located in the middle of the width direction of the foot plate (202). The length direction of the foot plate (202) is the direction from one end of the foot plate (202) and the annular heating part (201) to the other end. The width direction is perpendicular to the length direction.

3. The heater according to claim 2, characterized in that, The first slot structure (2021a) is a long slot structure extending along the length direction of the foot plate (202).

4. The heater according to claim 3, characterized in that, The first slot structure (2021a) extends to both ends of the foot plate (202), and the first slot structure (2021a) and the annular heating part (201) are offset.

5. The heater according to claim 1, characterized in that, The connecting part (2011) of the annular heating part (201) is provided with the slot structure, and the slot structure of the connecting part (2011) is defined as the second slot structure (2011a). The second slot structure (2011a) and the foot plate (202) are offset.

6. The heater according to any one of claims 1-5, characterized in that, The connecting part (2011) of the annular heating part (201) is provided with a plurality of first connecting holes (2011b), and the foot plate (202) is provided with a plurality of second connecting holes (20211a). The first connecting holes (2011b) and the second connecting holes (20211a) correspond one-to-one. The connecting part (2011) and the foot plate (202) are connected by fasteners (203) that are inserted into the corresponding first connecting holes (2011b) and second connecting holes (20211a).

7. The heater according to claim 6, characterized in that, The plurality of first connecting holes (2011b) of the connecting part (2011) form a plurality of hole groups, each hole group including at least two first connecting holes (2011b) distributed circumferentially along the annular heating part (201), the plurality of hole groups are distributed along the axial direction of the annular heating part (201), and the hole spacing of different hole groups is not equal; each hole group is symmetrically distributed relative to the axial direction of the annular heating part (201).

8. The heater according to claim 6, characterized in that, The connecting part (2011) has a first stepped surface (20112) and a first stepped sidewall (20111), and the foot plate (202) has a second stepped surface (20212) and a second stepped sidewall (20211). The first stepped sidewall (20111) of the connecting part (2011) abuts against the second stepped surface (20212), and the second stepped sidewall (20211) of the foot plate (202) abuts against the first stepped surface (20112). The first connecting hole (2011b) is provided on the side wall of the first step (20111), and the second connecting hole (20211a) is provided on the side wall of the second step (20211).

9. A single crystal furnace, characterized in that, It includes a furnace body (10) and a heater (20) located inside the furnace body (10), wherein the heater (20) is the heater (20) according to any one of claims 1-8.

10. The single crystal furnace according to claim 9, characterized in that, The single crystal furnace includes a gas duct (30) disposed at the bottom, and the foot plate (202) of the heater (20) extends toward the bottom of the single crystal furnace.

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