Heater and single crystal furnace

Abstract

The present application provides a heater and a single crystal furnace. The heater includes a heating body. The heating body is cup-shaped and has an opening at its bottom. The heating body is divided into a first heating zone and a second heating zone in a circumferential direction. The first heating zone includes a first main heating zone, and the second heating zone includes a second main heating zone. The first main heating zone and the second main heating zone are located at different heights in the axial direction of the heating body.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority from Chinese Patent Application No. 202210588892.6, filed in China on May 26, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the technical field of single crystal manufacturing, and in particular to heaters and single crystal furnaces. [Background technology]

[0003] As the quality requirements for semiconductor silicon wafers increase, there are greater demands for controlling crystal defects in the crystal rods during the crystal pulling process. The structure and performance of the hot zone directly affect the quality of the crystal rods, making hot zone design extremely important. For single crystal furnaces, heater design is one of the core aspects of hot zone design. The heater, which provides the thermal power of a single crystal furnace, plays a key role in the melting and later forming stages of polycrystalline silicon material. The heater's shape and the size of the heating zone directly affect the temperature field in the crystal pulling furnace, which in turn affects the quality of the crystal rods.

[0004] The heaters in the related art do not have high heating efficiency, and especially in the later stage of the crystal rod's isodiametric growth, the melt's heat retention capacity decreases as the melt decreases. This exacerbates the non-uniformity of the melt's temperature field. Furthermore, conventional heaters are limited by the heat transfer method, and the convection method is unfavorable for the effective precipitation of oxygen and the uniform radial penetration of oxygen in the crystal rod. This significantly limits the uniform distribution of oxygen in the crystal rod and affects the overall quality of the crystal rod. Summary of the Invention [Problem to be solved by the invention]

[0005] In view of this, the present application provides a heater and a single crystal furnace that can solve the problem of the low quality of the crystal rods in the related art, which has a low heating efficiency and is unfavorable for the effective precipitation of oxygen and the uniform radial penetration of oxygen into the crystal rods. [Means for solving the problem]

[0006] In order to solve the above technical problems, the present application employs the following technical means.

[0007] An embodiment of a first aspect of the present application provides a heater. The heater includes a heating body. The heating body is bowl-shaped to fit the outer shape of a crucible and has an opening at the bottom. The heating body is circumferentially divided into a first heating zone and a second heating zone. The first heating zone includes a first main heating zone, and the second heating zone includes a second main heating zone, and the first main heating zone and the second main heating zone are located at different heights in the axial direction of the heating body.

[0008] Optionally, the heating body includes a straight cylindrical portion and an arc portion that are arranged above and below the axial direction of the heating body and are connected together, and a first main heating zone of the first heating zone is located in the straight cylindrical portion, and a second main heating zone of the second heating zone is located in the arc portion.

[0009] Optionally, the heating body is divided into a plurality of successive heating strips by forming first grooves and second grooves alternately distributed in the circumferential direction. The first grooves extend from the upper end of the heating body toward the lower end thereof without penetrating the lower end. The second grooves extend from the lower end of the heating body toward the upper end thereof without penetrating the upper end. The second grooves located in the first heating zone extend to the region between two adjacent first grooves. The first grooves located in the second heating zone extend to the region between two adjacent second grooves.

[0010] Optionally, the ratio of the length of the portion of the second groove extending to a region between two adjacent first grooves to the height of the straight cylindrical portion is 1 / 2 to 2 / 3.

[0011] Optionally, the ratio of the length of the portion of the first groove extending to a region between two adjacent second grooves to the arc length of the arc portion is 3 / 4.

[0012] Optionally, the length of the portion of the first groove extending to the region between two adjacent second grooves is greater than the length of the portion of the second groove extending to the region between two adjacent first grooves.

[0013] Optionally, the height of the cylindrical portion is less than the arc length of the arc portion.

[0014] Optionally, the first heating zone and the second heating zone are obtained by dividing the heating body into two equal circumferential portions.

[0015] An embodiment of another aspect of the present application further provides a single crystal furnace including the heater according to the first aspect.

[0016] Optionally, the single crystal furnace further includes a crucible, the outer shape of which is bowl-shaped and the outer shape of the heating body of the heater. [Effects of the Invention]

[0017] According to the heater of the present invention, the bowl-shaped heating body conforms to the outer shape of the crucible, allowing for efficient heat transfer to the crucible and improving the heating efficiency of the heater. Furthermore, the first and second heating zones, divided circumferentially around the heating body, are separated into a first main heating zone within the first heating zone and a second main heating zone within the second heating zone. This asymmetry reduces the axial temperature difference between the center and edge of the crystal rod, resulting in a smooth solid-liquid interface, which is beneficial for growing defect-free crystal rods. Furthermore, the natural external convection of the melt can be modified to match the rotation speed of the crucible, allowing for effective control of oxygen precipitation. Furthermore, the surface tension of the melt is modified to exhibit a radial gradient, forming interfacial convection. This, combined with the internal convection caused by the crystal rotation, promotes uniform oxygen penetration into the crystal rod, improving the uniformity of the oxygen content in both the axial and radial directions of the crystal rod. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic assembly diagram of a heater according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram of a heating body according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0019] In order to clarify the purpose, technical means and advantages of the embodiments of the present application, the technical means of the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all of the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by those skilled in the art are all within the scope of protection of the present application.

[0020] Referring to FIGS. 1 and 2, FIG. 1 is a schematic assembly diagram of a heater according to an embodiment of the present application, and FIG. 2 is a schematic diagram of a heating body according to an embodiment of the present application. As shown in FIGS. 1 and 2, an embodiment of one aspect of the present application provides a heater for use in a single crystal furnace. The heater includes a heating body 1. The heating body 1 is bowl-shaped to fit the outer shape of a crucible. That is, a crucible for containing silicon material in a single crystal furnace is bowl-shaped. Specifically, this crucible is a graphite crucible 5. The heating body 1 of the heater also has the same bowl shape as the outer shape of the crucible, and corresponds to an equal expansion of the graphite crucible 5. This ensures that the distances between different parts of the heating body 1 and corresponding parts of the crucible are approximately the same, allowing heat generated in the heating body 1 to be uniformly transferred to the crucible and from the crucible to the silicon material in the crucible, thereby improving the heating efficiency of the heater.

[0021] In the embodiment of the present application, the heating body 1 is divided into a first heating zone and a second heating zone in the circumferential direction. The first heating zone includes a first main heating zone 111. The heating efficiency of this first main heating zone 111 is greater than the heating efficiency of other zones in the first heating zone other than the first main heating zone 111. Optionally, the first main heating zone 111 and the other zones are arranged one above the other. The second heating zone includes a second main heating zone 112. The heating efficiency of this second main heating zone 112 is greater than the heating efficiency of other zones in the second heating zone other than the second main heating zone 112. Optionally, the second main heating zone 112 and the other zones are arranged one above the other. Furthermore, the first main heating zone 111 and the second main heating zone 112 are located at different heights in the axial direction of the heating body 1. That is, the first main heating zone 111 of the first heating zones and the second main heating zone 112 of the second heating zones have different axial heights of the heating body 1, and the first main heating zone 111 and the second main heating zone 112 are asymmetric in the circumferential direction. As shown in FIG. 1, the heating direction formed by the first main heating zone 111 is mainly lateral radiation, while the heating direction formed by the second main heating zone 112 is mainly oblique upward radiation. During heating, the melt 3 generates natural external convection 6, and when the crystal rod 2 rotates, forced internal convection 7 is formed.

[0022] Therefore, the heater in the embodiment of the present application adopts the above-mentioned installation configuration, which reduces the difference ΔG between the axial temperature difference at the center of the crystal rod 2 and the axial temperature difference at the edge of the crystal rod 2, which is advantageous for smoothing the shape of the solid-liquid interface and growing a defect-free crystal rod. Furthermore, the natural external convection 6 of the melt 3 can be modified to match the rotation speed of the crucible, thereby controlling the effective precipitation of oxygen content. The surface tension of the melt 3 is modified to exhibit a gradient change in the radial direction to form interfacial convection, which, combined with the forced internal convection 7 caused by the rotation of the crystal rod 2, is advantageous for uniformly infiltrating oxygen into the crystal rod 2, improving the uniformity of the oxygen content in the axial and radial directions of the crystal rod 2 and improving the quality of the crystal rod 2.

[0023] In some embodiments of the present application, the heating body 1 includes a straight cylindrical portion 11 and an arcuate portion 12 that are integrally connected and disposed above and below the axial direction of the heating body 1. That is, the straight cylindrical portion 11 is located above the arcuate portion 12, and the straight cylindrical portion 11 has a straight cylindrical shape, while the arcuate portion 12 has an arcuate shape. Here, a first main heating zone 111 of the first heating zone is located in the straight cylindrical portion 11, and a second main heating zone 112 of the second heating zone is located in the arcuate portion 12. As a result, the first main heating zone 111 and the second main heating zone 112 are located at different heights in the axial direction of the heating body 1, achieving asymmetric installation.

[0024] In some embodiments of the present application, the heating body 1 has first grooves 8 and second grooves 9 that are alternately distributed in the circumferential direction. The first grooves 8 and second grooves 9 divide the heating body 1 into a plurality of heating strips that are connected sequentially, i.e., the plurality of heating strips are arranged in a series. Here, the first grooves 8 extend from the upper end of the heating body 1 to the lower end of the heating body 1 but do not penetrate the lower end. The second grooves 9 extend from the lower end of the heating body 1 to the upper end of the heating body 1 but do not penetrate the upper end. The second grooves 9 located in the first heating zone extend to the region between two adjacent first grooves 8. That is, the portion of the second groove 9 in the first heating zone is located in the region between two adjacent first grooves 8. The first grooves 8 located in the second heating zone extend to the region between two adjacent second grooves 9. That is, the portion of the first groove 8 in the second heating zone is located in the region between two adjacent second grooves 9. As a result, the first main heating zone 111 formed by the first groove 8 and the second groove 9 in the first heating zone is located in the straight cylinder portion 11, and the second main heating zone 112 formed by the first groove 8 and the second groove 9 in the second heating zone is located in the arc portion 12.

[0025] Optionally, the heating body 1 is also provided with pins for connecting with electrodes to facilitate connection of the heating body with an external power source and to realize electrical heating.

[0026] In another embodiment of the present application, in the first heating zone, the ratio of the length of the portion of the second groove 9 extending to the region between two adjacent first grooves 8 to the height of the straight cylindrical portion 11 is 1 / 2 to 2 / 3. Thus, by controlling the ratio of the length of the portion of the second groove 9 extending to the region between two adjacent first grooves 8 to the height of the straight cylindrical portion 11, it is possible to control the area size of the first main heating zone 111 in the first heating zone.

[0027] In another embodiment of the present application, in the second heating zone, the ratio of the length of the region where the first grooves 8 extend between two adjacent second grooves 9 to the arc length of the arc portion 12 is 3 / 4. Thus, by controlling the ratio of the length of the region where the first grooves 8 extend between two adjacent second grooves 9 to the arc length of the arc portion 12, it is possible to control the area size of the second main heating zone 112 in the second heating zone. Here, the arc length of the arc portion 12 is the length of the arc from the lower end to the upper end of the arc portion 12, and this arc is obtained by cutting the arc portion 12 with a plane passing through the axis of the heating body 1.

[0028] In some embodiments of the present application, the length of the portion of the second heating zone where the first groove 8 extends to the region between two adjacent second grooves 9 is greater than the length of the portion of the first heating zone where the second groove 9 extends to the region between two adjacent first grooves 8. That is, the heating efficiency of the second main heating zone 112 of the second heating zone is greater than the heating efficiency of the first main heating zone 111 of the first heating zone, which is advantageous for effective oxygen precipitation and radially uniform oxygen penetration in the crystal rod 2.

[0029] In another embodiment of the present application, the height of the straight cylinder portion 11 is smaller than the arc length of the arc portion 12. Here, the arc length of the arc portion 12 is the length of the arc from the lower end to the upper end of the arc portion 12, and this arc is obtained by cutting the arc portion 12 with a plane passing through the axis of the heating body 1. As a result, the heating range of the arc portion 12 in the axial direction of the heating body 1 is larger than the heating range of the straight cylinder portion 11 in the axial direction of the heating body 1. In other words, the heating efficiency of the arc portion 12 is greater than that of the straight cylinder portion 11, improving the natural external convection 6 of the melt 3 and the internal convection due to crystal rotation.

[0030] In some embodiments of the present application, the first heating zone and the second heating zone are obtained by dividing the heating body 1 in half in the circumferential direction. That is, the lengths of the first heating zone and the second heating zone in the circumferential direction of the heating body 1 are the same. Of course, in some embodiments, the lengths of the first heating zone and the second heating zone in the circumferential direction of the heating body 1 may be different. For example, the length of the first heating zone in the circumferential direction of the heating body 1 is 1 / 3 of the circumferential length of the heating body 1, and the length of the second heating zone in the circumferential direction of the heating body 1 is 2 / 3 of the circumferential length of the heating body 1. The specific dimensions are determined based on the design needs of the actual single crystal furnace and are not specifically limited in the embodiments of the present application.

[0031] In the present embodiment, the heater body 1 is bowl-shaped to fit the outer shape of the crucible, allowing for efficient heat transfer to the crucible and improving the heater's heating efficiency. Furthermore, the heater body is divided into a first heating zone and a second heating zone along its circumferential axis. The first main heating zone within the first heating zone and the second main heating zone within the second heating zone are located at different axial heights, i.e., asymmetrically. This reduces the difference between the axial temperature difference at the center of the crystal rod and the axial temperature difference at the edge of the crystal rod, resulting in a gentler solid-liquid interface and favoring the growth of defect-free crystal rods. Furthermore, the natural external convection of the melt can be modified to match the rotation speed of the crucible, allowing for effective control of oxygen content precipitation. The surface tension of the melt is modified to exhibit a radial gradient to form interfacial convection. This, combined with the forced internal convection caused by the crystal rotation, favors uniform oxygen penetration into the crystal rod and improves the uniformity of the oxygen content in the axial and radial directions of the crystal rod.

[0032] Another embodiment of the present application further provides a single crystal furnace, which includes the heater described in the above embodiment and can achieve the same technical effects, so its description will be omitted here to avoid redundancy.

[0033] In some embodiments of the present application, the single crystal furnace includes a crucible whose outer shape is bowl-shaped, and which is the same as the outer shape of the heating body 1 of the heater.

[0034] Specifically, as shown in FIGS. 1 and 2, the heater includes a heating body 1. The heating body 1 is bowl-shaped to fit the outer shape of a crucible. That is, a crucible for containing silicon material in a single crystal furnace is bowl-shaped. This crucible specifically includes a graphite crucible 5 and a quartz crucible 4 located inside the graphite crucible 5. The heating body 1 of the heater also has the same bowl shape as the outer shape of the graphite crucible 5, and is equivalent to enlarging the graphite crucible 5 in an equal proportion. This ensures that the distances between different parts of the heating body 1 and corresponding parts of the crucible are approximately the same, allowing the heat generated in the heating body 1 to be uniformly transferred to the crucible and from the crucible to the silicon material in the crucible, thereby improving the heating efficiency of the heater.

[0035] In the present embodiment, the heating body is bowl-shaped to fit the outer shape of the crucible, allowing for efficient heat transfer to the crucible and improving the heating efficiency of the heater. Furthermore, the heating body is divided into a first heating zone and a second heating zone. The first main heating zone and the second main heating zone are located at different axial heights, i.e., asymmetrically, which reduces the difference in axial temperature between the center and edge of the crystal rod. This reduces the difference in axial temperature between the center and edge of the crystal rod, resulting in a smooth solid-liquid interface, which is beneficial for growing defect-free crystal rods. Furthermore, the natural external convection of the melt can be modified to match the rotation speed of the crucible, allowing for effective control of oxygen precipitation. Furthermore, the surface tension of the melt is modified to exhibit a radial gradient to form interfacial convection, which, combined with internal convection due to crystal rotation, promotes uniform oxygen penetration into the crystal rod and improves the uniformity of the oxygen content in the axial and radial directions of the crystal rod.

[0036] The above are some embodiments of the present application, and those skilled in the art may make some improvements and refinements without departing from the principles described in the present application, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A heater including a heating body, The heating body has a bowl shape that fits the outer shape of the crucible and has an opening at the bottom of the heating body; The heating body is divided into a first heating zone and a second heating zone in a circumferential direction, the first heating zone includes a first main heating zone, and the heating efficiency of the first main heating zone is greater than the heating efficiency of other zones in the first heating zone other than the first main heating zone; the second heating zone includes a second main heating zone, and the heating efficiency of the second main heating zone is greater than the heating efficiency of other zones in the second heating zone other than the second main heating zone; the first main heating zone and the second main heating zone are located at different heights in the axial direction of the heating body; The heating body includes a straight cylindrical portion and an arc portion that are provided vertically in the axial direction of the heating body and are integrally connected to each other, a first main heating zone of the first heating zones is located in the cylindrical portion; a second main heating zone of the second heating zones being located in the arc portion;

2. The heating body is divided into a plurality of heating strips, each of which is connected to the other end, by forming first grooves and second grooves alternately distributed in a circumferential direction in the heating body; the first groove extends from an upper end of the heating body toward a lower end of the heating body, but does not penetrate the lower end of the heating body; the second groove extends from the lower end of the heating body toward the upper end of the heating body but does not penetrate the upper end of the heating body; the second groove located in the first heating zone extends to a region between two adjacent first grooves; the first groove located in the second heating zone extends to a region between two adjacent second grooves; 2. The heater of claim 1, wherein a first main heating zone formed by the first groove and the second groove of the first heating zone is located in a straight cylindrical portion, and a second main heating zone formed by the first groove and the second groove of the second heating zone is located in an arc portion.

3. 3. The heater according to claim 2, wherein a ratio of a length of a portion of the second groove extending to a region between two adjacent first grooves to a height of the straight cylindrical portion is 1 / 2 to 2 / 3.

4. 3. The heater according to claim 2, wherein a ratio of a length of a portion of the first groove extending to a region between two adjacent second grooves to an arc length of the arc portion is 3 / 4.

5. 3. The heater of claim 2, wherein a length of a portion of the first groove extending into a region between two adjacent second grooves is greater than a length of a portion of the second groove extending into a region between two adjacent first grooves.

6. The heater according to claim 1 , wherein the height of the cylindrical portion is smaller than the arc length of the arc portion.

7. The heater of claim 1 , wherein the first heating zone and the second heating zone are obtained by dividing the heating body into two equal parts in a circumferential direction.

8. A single crystal furnace comprising the heater according to any one of claims 1 to 7.

9. 9. The single crystal furnace of claim 8, further comprising a crucible having an outer shape that is bowl-shaped with the outer shape of the heating body of the heater.

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