TW202417697A - A guide tube and a crystal pulling furnace used in the process of pulling a crystal rod by a Czochralski method - Google Patents

Abstract

The embodiment of the present invention discloses a guide tube and a crystal pulling furnace used in the process of pulling a crystal rod by the Czochralski method. The bottom of the guide tube has a notch, which is used to change the flow rate of the protective gas flowing through the liquid surface of the melt in the reference diameter direction by rotating the guide tube around its own longitudinal axis.

Description

A guide tube and a crystal pulling furnace used in the process of pulling a crystal rod by a CZ method

The present invention belongs to the field of semiconductor silicon wafer production, and in particular to a guide tube and a crystal pulling furnace used in the process of Czochralski method crystal rod pulling.

Silicon wafers used to produce semiconductor electronic components such as integrated circuits are mainly produced by slicing single-crystal silicon rods pulled by the Czochralski method. The Czochralski method involves melting polycrystalline silicon in a crucible made of quartz to obtain a silicon melt, immersing a single crystal seed in the silicon melt, and continuously lifting the seed to move away from the surface of the silicon melt, thereby growing a single crystal silicon rod at the interface during the movement.

The oxygen concentration in the pulled single crystal silicon rod is an important factor affecting the performance of the silicon wafer. The oxygen in the single crystal silicon rod can enhance the strength of the silicon wafer, or form a bulk micro defect (BMD) in the silicon wafer. The role of BMD is to absorb metal impurities generated during the processing. However, oxygen deposition may also damage the performance of electronic devices, such as easily causing leakage current and device breakdown. Therefore, for electronic devices with different uses, there are different requirements for the size and distribution of their oxygen content, and these requirements are relatively harsh, which requires better control of the oxygen content in the crystal during crystal growth.

The oxygen in the single crystal silicon rod mainly comes from the melting of the quartz crucible, and its melting rate is related to the temperature and the convection of the melt. At present, the oxygen concentration in the drawn single crystal silicon rod is usually controlled by controlling the heating temperature of the quartz crucible, but on the other hand, the heating temperature of the quartz crucible should meet the requirements of production efficiency, which leads to interference between the oxygen concentration requirements in the single crystal silicon rod and the production efficiency requirements. Therefore, how to provide a method different from the heating temperature control of the quartz crucible to control the oxygen concentration in the drawn single crystal silicon rod has become a problem that needs to be solved urgently in this field.

To solve the above technical problems, the embodiments of the present invention hope to provide a guide tube and a crystal pulling furnace used in the process of pulling a crystal rod by the Czochralski method, which can control the oxygen concentration in the pulled single crystal silicon rod in a different way from controlling the heating temperature of the quartz crucible.

The technical solution of the present invention is implemented as follows: In the first aspect, the embodiment of the present invention provides a guide tube used in the process of CZT pulling a crystal rod, the bottom of the guide tube has a notch, and the notch is used to change the flow rate of the protective gas flowing through the liquid surface of the melt in the reference diameter direction by rotating the guide tube around its own longitudinal axis.

When the direction of the horizontal magnetic field applied to the melt is the above-mentioned reference radial direction, when the guide tube is located at a position where the notch is vertically opposite to the radial direction parallel to the horizontal magnetic field in the liquid surface of the melt, the protective gas will flow through the notch at the bottom of the guide tube in the direction of the horizontal magnetic field, so the flow rate will be relatively large, thereby promoting the volatility of oxygen in the melt, resulting in less oxygen reaching the solid-liquid interface between the crystal rod and the melt, reducing the oxygen concentration in the crystal rod, and when the guide tube is When the notch is not radially opposite to the liquid surface of the melt in the vertical direction and parallel to the horizontal magnetic field, the protective gas cannot flow through the notch at the bottom of the guide tube in the direction of the horizontal magnetic field, and can only flow through the gap between the part of the bottom of the guide tube where the notch is not formed and the liquid surface of the melt. Therefore, the flow rate will be relatively small, thereby inhibiting the volatility of oxygen in the melt, causing more oxygen to reach the solid-liquid interface between the crystal rod and the melt, thereby increasing the oxygen concentration in the crystal rod.

Preferably, the number of the notches is two and they are opposite to each other in the radial direction of the guide tube.

Since the area that can be affected by the flow rate of the protective gas flowing through the liquid surface of the melt for the volatilization of oxygen in the melt exists in the entire radial direction, the two radially opposite notches can make full use of such an area. For example, when it is necessary to lower the oxygen concentration in the pulled crystal rod, compared with the guide tube having only a single notch, the guide tube having two radially opposite notches can better promote the volatilization of oxygen from the melt and thus reduce the oxygen concentration.

Preferably, the guide tube is arranged so that a connecting line between two of the notches is parallel to a horizontal magnetic field applied to the melt.

In this case, for the protective gas flowing through the liquid surface of the melt, the flow rate is the largest in the direction parallel to the horizontal magnetic field, because the protective gas can flow through the notch at the bottom of the guide tube, or in other words, in the entire circumference of the guide tube, the gap between the part with the notch formed in the bottom and the liquid surface of the melt is the largest, thereby being able to obtain a crystal rod with an oxygen concentration as low as possible.

And in this case, the non-uniformity of oxygen concentration in the circumferential direction of the crystal rod is minimized.

Preferably, the guide tube is arranged so that a connecting line between two of the notches is perpendicular to a horizontal magnetic field applied to the melt.

In this case, for the protective gas flowing through the liquid surface of the melt, the flow rate is the smallest in the direction parallel to the horizontal magnetic field, because the protective gas can only flow through the gap between the portion of the bottom of the guide tube where no notch is formed and the liquid surface of the melt, or in other words, can only flow through the gap between the portion of the bottom of the guide tube that is convex relative to the notch and the liquid surface of the melt, and this gap is the smallest in the entire circumference of the guide tube, thereby obtaining a crystal rod with an oxygen concentration as high as possible.

Preferably, the notch is rectangular. In this way, for the protective gas flowing through the liquid surface of the melt, when, for example, the flow value at different positions on the circumference of the guide tube needs to be accurately calculated, the calculation process can be simplified.

Preferably, the recess gradually expands toward the bottom of the guide tube. In this way, when the recess is obtained by removing material, the guide tube with the recess can be manufactured more easily.

In a second aspect, an embodiment of the present invention further provides a crystal pulling furnace used in a process of pulling a crystal rod by the Czochralski method, wherein the crystal pulling furnace comprises a flow guide tube according to the first aspect.

Preferably, the crystal pulling furnace further comprises: A furnace body, which defines a furnace body cavity; A crucible, which is disposed in the furnace body cavity and contains the melt.

Preferably, the crystal pulling furnace further includes a heater, which is disposed in the furnace cavity and at the periphery of the crucible to heat the crucible, thereby melting the solid raw material contained in the crucible into the melt.

Preferably, the crystal pulling furnace further includes a heat-insulating element, which is arranged at the inner wall of the furnace body to inhibit the heat generated by the crucible heater from being lost through the furnace body.

The technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiment of the present invention.

First, refer to FIG1 , which shows a conventional crystal pulling furnace 1A for pulling a crystal rod R. The crystal pulling furnace may mainly include: a furnace body 20A; a crucible 30A, which is arranged inside the furnace body 20A and used to contain a melt M; a heater 40A, which is used to heat the crucible 30A to melt a solid raw material such as solid polycrystalline silicon into the melt M and to keep the melt M at a desired temperature; and a flow guide 10A, which is used to guide a protective gas such as argon, which is not shown in detail in FIG1 , to the liquid surface of the melt M to prevent the melt M from undergoing an undesired chemical reaction.

The oxygen contained in the pulled crystal rod R mainly comes from the crucible 30A. Specifically, the crucible 30A will be melted under the high temperature of the melt M, and the oxygen contained in the crucible 30A will enter the melt M. If the oxygen in the melt M reaches the solid-liquid interface between the crystal rod R and the melt M, it will enter the crystal rod R.

On the other hand, in the crystal pulling furnace 1A, under the heating effect of the heater 40A, the melt M contained in the crucible 30A will generate thermal convection, and the instability of the melt M caused by the thermal convection will affect the crystal pulling. In order to reduce the intensity of the convection in the melt M, a magnetic field is applied to the melt M to slow down the convection in the melt M through the Lorenz force. The types of applied magnetic fields can be divided into vertical magnetic fields, horizontal magnetic fields, and hook-shaped magnetic fields. These magnetic fields have their own advantages and disadvantages, and the horizontal magnetic field HM shown in Figure 1 can provide the highest intensity magnetic field (up to 0.4T) because the required coil diameter is smaller than that of the other two magnetic fields. However, the problem with the horizontal magnetic field HM is that it provides a non-centrally symmetric magnetic field compared to the other two magnetic fields, which leads to complex asymmetry in the convection in the melt M.

Oxygen generated by the melting of the crucible 30A under the high temperature of the melt M mainly exists at the inner wall of the crucible 30A, and flows along with the convection of the melt M formed under the horizontal magnetic field HM, thereby reaching the solid-liquid interface between the crystal rod R and the melt M. The following is a detailed description of the situation in which the oxygen existing on the inner wall of the crucible 30A reaches the solid-liquid interface between the crystal rod R and the melt M in combination with the convection of the melt M formed under the horizontal magnetic field HM.

2 , which shows a schematic diagram of the flow trajectory of the melt M under the combined effect of the heater 40A and the horizontal magnetic field HM shown in FIG. 1 , wherein the crystal pulling furnace 1A shown in FIG. 1 and the flow trajectory shown in FIG. 2 are in the same coordinate system XYZ. Combining FIG. 1 and FIG. 2 , it can be seen that: in the XZ plane perpendicular to the horizontal magnetic field HM, due to the existence of a relatively large and stable eddy current, the oxygen melted at the inner wall of the crucible 30A will quickly reach the free surface of the melt M along with the eddy current and evaporate rapidly; however, in the vertical plane parallel to the horizontal magnetic field HM, i.e., the XY plane, the melt M at the inner wall of the crucible 30A tends to flow toward the center of the entire melt M, that is, in this plane, it is difficult for the oxygen melted from the crucible 30A to flow to the free surface of the melt M in time and evaporate, and it is easier to flow to the solid-liquid interface to cause an increase in the oxygen concentration of the crystal rod R.

In this case, it is easy to understand that if one wants to influence the volatilization of oxygen in the melt M by the flow rate of the protective gas flowing through the liquid surface of the melt M: assuming that the protective gas flows in the direction of the Z axis, or in other words, in the direction perpendicular to the horizontal magnetic field HM, then no matter what the flow rate of the protective gas is, it will not affect the volatilization of oxygen, because in this direction, the oxygen in the melt M has mainly reached the free surface of the melt M and volatilized; however, assuming that the protective gas flows in the Y axis, If the protective gas flows in the direction of the axis, or in other words, flows in a direction parallel to the horizontal magnetic field HM, then when the flow rate of the protective gas is large, the volatilization of oxygen in the melt M will be promoted, thereby causing less oxygen to reach the solid-liquid interface between the crystal rod R and the melt M, and reducing the oxygen concentration in the crystal rod R. When the flow rate of the protective gas is small, the volatilization of oxygen in the melt M will be suppressed, thereby causing more oxygen to reach the solid-liquid interface between the crystal rod R and the melt M, and increasing the oxygen concentration in the crystal rod R.

On this basis, referring to FIGS. 3 to 5 , an embodiment of the present invention provides a guide tube 10 used in a process of pulling a crystal rod R as shown in FIG. 1 by a CZ method. As shown in the three-dimensional view of FIG. 3 and the cross-sectional view of FIG. 4 , the bottom 10B of the guide tube 10 may have a notch 10N, and the notch 10N is used to change the flow rate of the protective gas PG flowing through the liquid surface L of the melt M in the reference diameter direction by rotating the guide tube 10 around its longitudinal axis 10X. Specifically, assuming that the direction of the horizontal magnetic field HM is the above-mentioned reference radial direction, when the guide tube 10 is at the position shown in FIG. 4 relative to the horizontal magnetic field HM, in the direction of the horizontal magnetic field HM, or in the direction of the Y axis shown in FIGS. 1 and 2 , the protective gas PG will flow through the notch 10N at the bottom 10B of the guide tube 10, so the flow rate will be relatively large, thereby promoting the volatilization of oxygen in the melt M as mentioned above, resulting in less oxygen reaching the solid-liquid interface between the crystal rod R and the melt M, reducing the oxygen concentration in the crystal rod R, and when the guide tube 10 is at the position shown in FIG. 4 relative to the horizontal magnetic field HM, the protective gas PG will flow through the notch 10N at the bottom 10B of the guide tube 10, so the flow rate will be relatively large, thereby promoting the volatilization of oxygen in the melt M as mentioned above, resulting in less oxygen reaching the solid-liquid interface between the crystal rod R and the melt M, reducing the oxygen concentration in the crystal rod R, and when the guide tube 10 is at the position shown in FIG. When the planar magnetic field HM is at the position shown in FIG. 5 , in the direction of the horizontal magnetic field HM, or in the direction of the Y axis shown in FIGS. 1 and 2 , the protective gas PG cannot flow through the notch 10N of the bottom 10B of the flow guide tube 10, and can only flow through the gap between the portion of the bottom 10B of the flow guide tube 10 where the notch 10N is not formed and the liquid surface L of the melt M. Therefore, the flow rate will be relatively small, thereby suppressing the volatilization of oxygen in the melt M as mentioned above, causing more oxygen to reach the solid-liquid interface between the crystal rod R and the melt M, thereby increasing the oxygen concentration in the crystal rod R.

That is, the embodiment of the present invention provides a guide tube 10 having a notch 10N at its bottom 10B, and the oxygen concentration in the pulled crystal rod R can be controlled by rotating the guide tube 10 around its longitudinal axis 10X.

In an optional embodiment of the present invention, referring to Fig. 3 and Fig. 4, the number of the notches 10N can be two and they are opposite in the radial direction of the guide tube 10. As mentioned above, for the volatilization of oxygen in the melt M, the area that can be affected by the flow rate of the protective gas PG flowing through the liquid surface L of the melt M exists in the entire radial direction, so the two notches 10N opposite in the radial direction can make full use of such an area. For example, when the oxygen concentration in the pulled crystal rod R needs to be lower, compared with the guide tube 10 having only a single notch 10N, the guide tube 10 having two notches 10N opposite in the radial direction can better promote the volatilization of oxygen from the melt M and thus reduce the oxygen concentration.

For the pulled crystal rod R, it may be necessary to have a higher oxygen concentration. In this regard, in an optional embodiment of the present invention, referring to FIG5 , the guide tube 10 may be arranged so that the connection line between the two notches 10N is perpendicular to the horizontal magnetic field HM applied to the melt M, wherein, since FIG5 is a cross-sectional view, the notch 10N is not shown, but it can be understood that the connection line between the two notches 10N of the guide tube 10 is perpendicular to the page showing FIG5 . In this case, for the protective gas PG flowing through the liquid surface L of the melt M, the flow rate is the smallest in the direction parallel to the horizontal magnetic field HM, because the protective gas PG can only flow through the gap between the portion of the bottom 10B of the guide tube 10 where the notch 10N is not formed and the liquid surface L of the melt M, or in other words, can only flow through the gap between the portion of the bottom 10B of the guide tube 10 that is raised relative to the notch 10N and the liquid surface L of the melt M, and this gap is the smallest in the entire circumferential direction of the guide tube 10.

For the drawn crystal rod R, its oxygen concentration may need to be relatively low. In addition, in addition to the requirements for the oxygen concentration of the entire crystal rod R, the oxygen concentration may also need to be uniform in the circumferential direction of the crystal rod R.

In this regard, in an optional embodiment of the present invention, referring to FIG. 4 , the guide tube 10 may be arranged so that a connecting line between the two notches 10N is parallel to the horizontal magnetic field HM applied to the melt M, wherein FIG. 4 is a cross-sectional schematic diagram of the guide tube 10 after rotating 90° around its longitudinal axis 10X on the basis of FIG. 5 , or in other words, FIG. 5 is a cross-sectional schematic diagram of the guide tube 10 after rotating 90° around its longitudinal axis 10X on the basis of FIG. 4 , so that in FIG. 4 , the connecting line between the two notches 10N of the guide tube 10 is in the cross section.

In this case, for the protective gas PG flowing through the liquid surface L of the melt M, the flow rate is the largest in the direction parallel to the horizontal magnetic field HM, because the protective gas PG can flow through the recess 10N of the bottom 10B of the guide tube 10, or in other words, in the entire circumference of the guide tube 10, the gap between the portion of the bottom 10B where the recess 10N is formed and the liquid surface L of the melt M is the largest.

Regarding the uniformity of oxygen concentration in the circumferential direction of the crystal rod R, as mentioned above, the oxygen in the crystal rod R mainly comes from the oxygen entering the melt M due to the melting of the crucible 30A at high temperature. However, under the action of the horizontal magnetic field HM, the temperature of the melt M in its own circumferential direction is uneven. Specifically, see Figure 6, which shows a schematic diagram of the temperature distribution of the melt M in a plane parallel to the liquid surface under the action of the heater 40A shown in Figure 1. As can be seen from Figure 6, in the direction parallel to the horizontal magnetic field HM, the temperature of the melt M near the crucible 30A is higher, so the crucible 30A will melt more and more oxygen will enter the melt M. In the direction perpendicular to the horizontal magnetic field HM, the temperature of the melt M near the crucible 30A is lower, so the crucible 30A will melt less and less oxygen will enter the melt M. Without considering the convection caused by the horizontal magnetic field HM as shown in Figure 2, or in other words, assuming that the probability of oxygen entering the melt M reaching the solid-liquid interface between the crystal rod R and the melt M is consistent, then, in the direction parallel to the horizontal magnetic field HM, more oxygen will enter the melt M, and therefore more oxygen will enter the crystal rod R, and in the direction perpendicular to the horizontal magnetic field HM, less oxygen will enter the melt M, and therefore less oxygen will enter the crystal rod R, thereby making the oxygen concentration of the crystal rod R in the circumferential direction uneven and more specifically, the oxygen concentration in the direction parallel to the horizontal magnetic field HM is greater than the oxygen concentration in the direction perpendicular to the horizontal magnetic field HM. On the other hand, under the action of convection as shown in FIG2 , as mentioned above, in the direction parallel to the horizontal magnetic field HM, the oxygen in the melt M is difficult to volatilize, which increases the oxygen concentration of the crystal rod R, and in the direction perpendicular to the horizontal magnetic field HM, the oxygen in the melt M is easy to volatilize, which inhibits the increase of the oxygen concentration of the crystal rod R. In other words, the unevenness of the oxygen concentration of the crystal rod R in the circumferential direction is further aggravated or worsened. In this embodiment, as mentioned above, the flow rate of the protective gas PG flowing through the liquid surface L of the melt M in the direction parallel to the horizontal magnetic field HM is maximized, thereby promoting the volatilization of oxygen in the melt M to the greatest extent, and the minimum amount of oxygen reaches the solid-liquid interface between the crystal rod R and the melt M, so that the oxygen concentration in the radial direction parallel to the horizontal magnetic field HM in the crystal rod R is minimized, thereby minimizing the unevenness of the oxygen concentration of the crystal rod R in the circumferential direction.

In an alternative embodiment of the present invention, referring to Fig. 3 , the notch 10N may be rectangular. In this way, for the protective gas PG flowing through the liquid surface L of the melt M, when, for example, the flow rate values at different positions on the circumference of the guide tube 10 need to be accurately calculated, the calculation process can be simplified.

In an alternative embodiment of the present invention, referring to Fig. 7, the recess 10N may gradually expand toward the bottom 10B of the guide tube 10. In this way, when the recess 10N is obtained by removing material, the guide tube 10 having the recess 10N can be manufactured more easily.

8 , an embodiment of the present invention further provides a crystal pulling furnace 1 used in a process of pulling a crystal rod R by the Czochralski method. The crystal pulling furnace 1 may include a guide tube 10 according to the above embodiments of the present invention.

In an optional embodiment of the present invention, the crystal pulling furnace 1 may further include: A furnace body 20, wherein the furnace body 20 defines a furnace body cavity 20C; A crucible 30, wherein the crucible 30 is disposed in the furnace body cavity 20C, and the melt M is contained in the crucible 30.

In an optional embodiment of the present invention, referring to FIG. 8 , the crystal pulling furnace 1 may further include a heater 40, which is disposed in the furnace cavity 20C and at the periphery of the crucible 30 to heat the crucible 30, thereby melting the solid raw material contained in the crucible 30 into the melt M.

In an optional embodiment of the present invention, referring to FIG. 8 , the crystal pulling furnace 1 may further include a heat-insulating element 50 , which is disposed at the inner wall of the furnace body 20 to suppress the heat generated by the heater 40 from being lost through the furnace body 20 .

Unless otherwise defined, the technical or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the utility model belongs. "First", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and other similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, but do not exclude other elements or objects. "Connect" or "connected" and other similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

It should be noted that the technical solutions described in the embodiments of the present invention can be combined arbitrarily without conflict.

The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any technical personnel familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the patent application of the present invention.

1: Crystal pulling furnace 1A: Crystal pulling furnace 10: Flow tube 10A: Flow tube 10B: Bottom 10N: Notch 10X: Longitudinal axis 20: Furnace body 20A: Furnace body 20C: Furnace body cavity 30: Crucible 30A: Crucible 40: Heater 40A: Heater 50: Insulation element HM: Horizontal magnetic field L: Liquid level M: Melt PG: Protective gas R: Crystal rod

Figure 1 is a schematic diagram of the structure of a conventional crystal pulling furnace for pulling crystal rods; Figure 2 is a schematic diagram of the trajectory of melt flow under the combined action of the heater and the horizontal magnetic field shown in Figure 1; Figure 3 is a three-dimensional schematic diagram of a guide tube used in the process of CZO-pulling crystal rods according to an embodiment of the present invention; Figure 4 is a cross-sectional schematic diagram of the guide tube according to an embodiment of the present invention when it is in a first position relative to the horizontal magnetic field; Figure 5 is a cross-sectional schematic diagram of the guide tube according to an embodiment of the present invention when it is in a second position relative to the horizontal magnetic field; Figure 6 is a schematic diagram of the temperature distribution of the melt in a plane parallel to the liquid surface under the action of the heater shown in Figure 1; Figure 7 is a front view schematic diagram of a guide tube used in the process of CZO-pulling crystal rods according to another embodiment of the present invention; FIG8 is a schematic diagram of the structure of a crystal pulling furnace used in the process of pulling a crystal rod by the Czochralski method according to an embodiment of the present invention.

10: Guide tube

10B: Bottom

10N: Notch

10X: Longitudinal axis

Claims (10)

A guide tube used in the process of Czochralski crystal rod pulling has a notch at the bottom. The notch is used to change the flow rate of a protective gas flowing through the liquid surface of a melt in a reference diameter direction by rotating the guide tube around its own longitudinal axis. A guide tube as described in claim 1, wherein the number of the notches is two and they are radially opposite to each other on the guide tube. The flow guide sleeve as described in claim 2, wherein the flow guide sleeve is arranged so that a connecting line between two of the notches is parallel to a horizontal magnetic field applied to the melt. A flow guide sleeve as described in claim 2, wherein the flow guide sleeve is arranged so that a connecting line between two of the notches is perpendicular to a horizontal magnetic field applied to the melt. A guide tube as described in any one of claims 1 to 4, wherein the recess is rectangular. A flow guide tube as described in any one of claims 1 to 4, wherein the recess gradually expands toward the bottom of the flow guide tube. A crystal pulling furnace used in a process of pulling a crystal rod by the Czochralski method, the crystal pulling furnace comprising the guide tube as described in any one of claims 1 to 6. The crystal pulling furnace as described in claim 7, wherein the crystal pulling furnace further comprises: a furnace body, the furnace body defining a furnace body cavity; a crucible, the crucible being disposed in the furnace body cavity, the melt being contained in the crucible. The crystal pulling furnace as described in claim 8, wherein the crystal pulling furnace further includes a heater, which is arranged in the furnace cavity and on the periphery of the crucible to heat the crucible, thereby melting the solid raw material contained in the crucible into the melt. The crystal pulling furnace as described in claim 9, wherein the crystal pulling furnace further includes a heat insulation element, which is arranged on the inner wall of the furnace body to inhibit the heat generated by the heater from being dissipated through the furnace body.

Images