CN117005020A - A process to improve the early crystallization rate of shoulder expansion and equal diameter of large-sized single crystals - Google Patents

Abstract

The invention provides a process for improving large-size single crystal shoulder expansion and equal-diameter pre-crystallization rate, which includes: a first shoulder expansion stage and a second shoulder expansion stage. In the first shoulder expansion stage, the crucible is moved from the first position to the first shoulder expansion stage. Adjust to the second position, and then use the first drawing speed to draw the first shoulder, and reduce the temperature during the drawing process; in the second shoulder expansion stage, the crucible position remains unchanged, and the first drawing speed is changed to the second shoulder. Second drawing speed, use the second drawing speed to continue drawing the second shoulder section at the bottom of the first shoulder section, and continue to reduce the temperature during the drawing process to complete the shoulder expansion. The beneficial effect of the present invention is that the only one shoulder in the prior art is divided into two shoulders for drawing, thereby increasing the surface area of the entire expanded shoulder part, thereby speeding up the heat dissipation speed from a physical point of view, increasing the heat dissipation capacity of the single crystal, and making the The interface flipping process in single crystal growth is accelerated from the equal diameter stage to the shoulder expansion stage, and the interface flip is completed in the shoulder expansion stage.

Description

A process to improve the early crystallization rate of shoulder expansion and equal diameter of large-sized single crystals

Technical field

The invention belongs to the field of photovoltaic semiconductor process technology, and in particular relates to a process for improving the shoulder expansion and equal diameter pre-crystallization rates of large-size single crystals.

Background technique

In the process of growing single crystal silicon by Czochralski method, shoulder expansion (also called shoulder release) is one of the key steps in the entire crystal pulling process. The main purpose of shoulder expansion is to increase the pulling speed by lowering the melt temperature and combining the crystal with the crystal. Enlarge from seed diameter to maintaining diameter. Unreasonable shoulder expansion technology will directly lead to shoulder expansion and bract breakage or early equal diameter bract breakage.

During the growth process of large-sized single crystals, due to the large diameter of the single crystal, the overall heat dissipation capacity is weaker than that of conventional M2 single crystals. The growth interface of the single crystal is convex to the liquid surface or saddle-shaped, resulting in the shoulder expansion and bud breakage of the large-sized single crystal. The proportion of broken bracts is high in the early stage of equal diameter.

Contents of the invention

The problem to be solved by the present invention is to provide a process for improving the early crystallization rate of shoulder expansion and equal diameter of large-sized single crystals, and effectively solve the problem that during the growth process of large-sized single crystals, due to the large diameter of the single crystals, the overall heat dissipation capacity is higher than that of conventional M2 The single crystal is weak, and the growth interface of the single crystal is convex to the liquid surface or saddle-shaped, which leads to the problem of shoulder expansion and breakage of large-sized single crystals, and a high proportion of breakage in the early stage of equal diameter.

In order to solve the above technical problems, the technical solution adopted by the present invention is: a process for improving the shoulder expansion and equal diameter pre-crystallization rate of large-sized single crystals, including:

In the temperature stabilization stage, the crucible position is adjusted to the first position during the temperature stabilization process;

The shoulder expansion stage includes the first shoulder expansion stage and the second shoulder expansion stage, wherein,

In the first shoulder expansion stage, the crucible position is adjusted from the first position to the second position, and then the first shoulder section is drawn using the first drawing speed, and the temperature is lowered during the drawing process;

In the second shoulder expansion stage, the crucible position remains unchanged, the first pulling speed is changed to the second pulling speed, and the second pulling speed is used to continue drawing at the bottom of the first shoulder section. The second shoulder section continues to lower the temperature during the drawing process, and the shoulder expansion is completed.

Preferably, the first position is a position where the liquid level in the crucible is 20-30 mm away from the guide tube.

Preferably, the second position is a position where the liquid level in the crucible is 15-25 mm away from the guide tube.

Preferably, the first pulling speed range is 50-65mm/h.

Preferably, the second pulling speed is higher than the first pulling speed, and is in the range of 70-90mm/h.

Preferably, in the first shoulder expansion stage, the power of the heater is reduced to reduce the temperature during the drawing process, wherein the reduction range of the first power is 7-17kw.

Preferably, in the second shoulder expansion range, the power of the heater is continued to be reduced to perform temperature cooling, wherein the reduction range of the second power is 3-8 kw.

Preferably, the height of the first shoulder section is H1, and the height of the second shoulder section is H2, wherein the ratio range of H1:H2 is 1:1-2:1.

Using the above technical solution, the only one shoulder in the prior art is divided into two shoulders for drawing, so that the outer surfaces of the two shoulder sections form a certain angle, increasing the surface area of the entire shoulder expansion part, thereby speeding up heat dissipation from a physical perspective speed, increasing the heat dissipation capacity of the single crystal, accelerating the interface flipping process in the growth of the single crystal from the equal diameter stage to the shoulder expansion stage. In the shoulder expansion stage, it completes the interface flip, that is, the growth interface of the single crystal changes from convex to the liquid surface. Turn over to the concave surface.

Using the above technical solution, by changing the position of the crucible, the speed of segmented drawing and the power of cooling to ensure the formation of the second shoulder, avoid the formation of a saddle-shaped single crystal interface as much as possible, and speed up the flipping speed of the single crystal growth interface. , thereby improving the early-stage crystallization rate of shoulder expansion and equal diameter of large-size single crystals, and at the same time increasing the output.

Description of the drawings

Figure 1 is a simulation diagram of the growth interface of a shoulder-expanded single crystal in a process for improving the shoulder-expanding and equal-diameter pre-crystallization rates of large-sized single crystals according to an embodiment of the present invention.

Figure 2 is a simulation diagram of the single crystal growth interface in the prior art of the present invention.

In the picture:

1. The first shoulder section 2. The second shoulder section

Detailed ways

The present invention will be further described below in conjunction with the examples and drawings:

In the description of the embodiments of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying it. The description does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore is not to be construed as a limitation of the invention. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

A process to improve the early-stage crystallization rate of shoulder expansion and equal diameter of large-size single crystals, including:

S1: Temperature stabilization stage, during the temperature stabilization process, adjust the crucible position to the first position;

The crucible position is the crucible position. In the present invention, it represents the position where the molten raw material liquid level in the crucible is at a certain distance from the bottom of the guide tube. The first position is the position where the liquid level in the crucible is 20-30mm away from the bottom of the guide tube. Preferably, the liquid level in the crucible is 22-28mm from the bottom of the guide tube, and more preferably, the liquid level in the crucible is 24mm, 25mm, or 26mm from the bottom of the guide tube;

Compared with the existing technology, the crucible position in the temperature stabilization stage is lowered by 5-15mm, which can change the crystallization area and the shape of the shoulder. At the same time, it accelerates the flipping of the single crystal growth interface so that it can complete the interface during the shoulder expansion stage. Flip to improve the crystallization rate of single crystals;

After adjusting the crucible position to the first position, it remains stationary until the temperature stabilization phase is completed and the next shoulder expansion phase is entered.

S2: Shoulder expansion stage, which includes the first shoulder expansion stage and the second shoulder expansion stage. It should be noted that the lower the crystal pulling speed or the smaller the longitudinal temperature gradient, the greater the degree of the single crystal growth interface convex to the liquid surface; the crystal The higher the pulling speed or the greater the longitudinal temperature gradient, the greater the concaveness of the single crystal growth interface toward the liquid surface, where,

S21: In the first shoulder expansion stage, adjust the crucible position from the first position to the second position, and then use the first drawing speed to draw the first shoulder section 1, and reduce the temperature during the drawing process;

The meaning of the crucible position is consistent with that in S1. The second position of the crucible position is 15-25mm from the liquid level in the crucible to the bottom of the flow guide tube, preferably 17-23mm from the bottom of the flow guide tube to the liquid level in the crucible, more preferably are 18mm, 19mm, 20mm, 21mm, and 22mm from the liquid level in the crucible to the bottom of the guide tube;

When the crucible position moves from the first position to the second position, start pulling the single crystal, and use the first pulling speed to pull the first shoulder 1, where the first pulling speed range is 50-65mm/h, and the preferred range is is 55-60mm/h, more preferably, the first pulling speed is 56mm/h, 57mm/h, 58mm/h, 59mm/h;

Compared with the existing technology, the drawing speed in the first shoulder expansion stage changes slightly and is basically unchanged, and the first shoulder 1 is drawn normally;

In the first shoulder expansion stage, the crystal pulling temperature needs to be lowered. The cooling method used in the present invention is to reduce the power of the heater to cool down during the drawing process, where,

The first power reduction range is 7-17kw, preferably 10-15kw, more preferably 11kw, 12kw, 13kw, 14kw; compared with the existing technology, the power reduction range is increased by 2-5kw, that is, more power is reduced The heater power makes the temperature in the single crystal furnace lower;

When the shoulder length of the first section of shoulder 1 is drawn to H1, the first shoulder expansion stage ends;

The shoulder length is the height of the shoulder. In the present invention, it represents the shortest distance from the top to the bottom of the shoulder, that is, the vertical distance. Generally, H1 is between one-half and one-third of the overall shoulder length, preferably 35-45% of the overall shoulder length, more preferably 40% of the overall shoulder length;

S22: In the second shoulder expansion stage, the crucible position remains unchanged, change the first pulling speed to the second pulling speed, use the second pulling speed to continue drawing the second shoulder 2 at the bottom of the first shoulder, and During the drawing process, the temperature continues to be lowered and the shoulder expansion is completed;

The meaning of the crucible position is consistent with S1. In the second shoulder expansion stage, the second position of the crucible position is kept unchanged, consistent with step S21. The liquid level in the crucible is 15-25mm from the bottom of the guide tube, preferably inside the crucible. The liquid level in the crucible is 17-23mm from the bottom of the guide tube, and more preferably, the liquid level in the crucible is 18mm, 19mm, 20mm, 21mm, or 22mm from the bottom of the guide tube;

Continue to draw the second shoulder 2 at the bottom of the first shoulder 1, and use the second drawing speed to draw the second shoulder 2. The second drawing speed is higher than the first drawing speed, and its range is 70-90mm/ h, the preferred range is 75-85mm/h, more preferably 78mm/h, 79mm/h, 80mm/h, 81mm/h, 82mm/h, 83mm/h;

Compared with the existing technology, the second pulling speed is increased by 0-40mm/h. Accelerating the pulling speed during the second shoulder expansion process can change the shape of the shoulder, as shown in Figures 1 and 2, making the first section shoulder 1 and An included angle is formed between the second shoulders 2. The angle of the included angle is generally 150-180° (excluding 180°), and the interface flipping in the second shoulder 2 can be accelerated and the growth interface of the single crystal can be flipped. Over, the liquid surface changes from convex to concave, thereby increasing the crystallization rate of single crystals;

In the second shoulder expansion stage, the crystal pulling temperature needs to be lowered. The cooling method used in the present invention is to reduce the power of the heater to cool down during the drawing process, where,

Continue to reduce the power of the heater after reducing the power in the first shoulder expansion stage, so as to cool down again, wherein the reduction range of the second power is 3-8kw, preferably 4-7kw, and more preferably 5kw, 6kw, 7kw ;

Compared with the power reduction of the existing technology, the power reduction in this process is reduced by 2-5kw, that is, the temperature in the single crystal furnace is relatively appropriately increased to a certain extent, and the purpose is also to cooperate with the increased second pulling speed to pull the single crystal. system, accelerating the flipping of the single crystal growth interface;

When the shoulder length of the second section of shoulder 2 is drawn to H2, the shoulder expansion step ends;

Shoulder length is the height of the shoulder. In the present invention, it represents the shortest distance from the top to the bottom of the shoulder, that is, the vertical distance. Generally, the ratio range of H1:H2 is 1:1-2:1, and H2 is the overall shoulder length. Between one-half and two-thirds of the overall shoulder length, preferably 55-65% of the overall shoulder length, and more preferably 60% of the overall shoulder length.

Since the overall shoulder shape in the shoulder expansion stage is changed to a two-section shoulder, the outer surface area of the overall shoulder is increased, which directly increases the heat dissipation capacity of the single crystal from a physical point of view, and advances the growth interface flipping process of the single crystal. During the shoulder expansion process, the number of expansion or bud breakage is reduced, and the yield loss is reduced, which means that the large-size single crystal shoulder expansion and equal diameter pre-crystallization rate are increased, and the output is increased.

Here are a few examples:

Example 1

S1: Temperature stabilization stage, during the temperature stabilization process, adjust the crucible position to the first position;

The crucible position is the crucible position. In the present invention, it represents the position where the molten raw material liquid level in the crucible is at a certain distance from the bottom of the flow guide tube. The first position is the position where the liquid level in the crucible is 20mm away from the bottom of the flow guide tube;

Compared with the crucible position in the temperature stabilization stage in the existing technology, the distance is reduced by a certain distance, which can change the crystallization area and the shape of the shoulder. At the same time, it speeds up the interface flip of single crystal growth so that it can complete the interface flip in the shoulder expansion stage. , improve the crystallization rate of single crystal;

After adjusting the crucible position to the first position, it remains stationary until the temperature stabilization phase is completed and the next shoulder expansion phase is entered.

S2: Shoulder expansion stage, which includes the first shoulder expansion stage and the second shoulder expansion stage. It should be noted that the lower the crystal pulling speed or the smaller the longitudinal temperature gradient, the greater the degree of the single crystal growth interface convex to the liquid surface; the crystal The higher the pulling speed or the greater the longitudinal temperature gradient, the greater the concaveness of the single crystal growth interface toward the liquid surface, where,

S21: In the first shoulder expansion stage, adjust the crucible position from the first position to the second position, and then use the first drawing speed to draw the first shoulder section 1, and reduce the temperature during the drawing process;

The meaning of the crucible position is consistent with that in S1. The second position of the crucible position is 15mm from the liquid level in the crucible to the bottom of the guide tube;

When the crucible moves from the first position to the second position, start pulling the single crystal, and use the first pulling speed to pull the first section 1, where the first pulling speed is 50mm/h;

In the first shoulder expansion stage, the crystal pulling temperature needs to be lowered. The cooling method used in the present invention is to reduce the power of the heater to cool down during the drawing process, where,

The first power reduction is 7kw;

When the shoulder length of the first section of shoulder 1 is drawn to H1, the first shoulder expansion stage ends;

The shoulder length is the height of the shoulder. In the present invention, it represents the shortest distance from the top to the bottom of the shoulder, that is, the vertical distance. In this embodiment, H1 is one-third of the overall shoulder length;

S22: In the second shoulder expansion stage, the crucible position remains unchanged, change the first pulling speed to the second pulling speed, use the second pulling speed to continue drawing the second shoulder 2 at the bottom of the first shoulder, and During the drawing process, the temperature continues to be lowered and the shoulder expansion is completed;

The meaning of the crucible position is consistent with that in S1. In the second shoulder expansion stage, the second position of the crucible position remains unchanged, which is consistent with step S21. The liquid level in the crucible is 15mm from the bottom of the guide tube;

Continue to draw the second shoulder 2 at the bottom of the first shoulder 1, and use the second drawing speed to draw the second shoulder 2, where the second drawing speed is higher than the first drawing speed and is 70mm/h;

Compared with the existing technology, increasing the pulling speed during the second shoulder expansion process can change the shape of the shoulder, so that an included angle is formed between the first shoulder 1 and the second shoulder 2. The included angle is generally 150- 180° (excluding 180°), and can accelerate the interface flip in the second shoulder 2, flip the growth interface of the single crystal over, and change it from convex to the liquid surface to concave to the liquid surface, thereby improving the crystallization of the single crystal. Rate;

In the second shoulder expansion stage, the crystal pulling temperature needs to be lowered. The cooling method used in the present invention is to reduce the power of the heater to cool down during the drawing process, where,

Continue to reduce the power of the heater after reducing the power in the first shoulder expansion stage, so as to cool down again, in which the second power reduction is 8kw;

Compared with the power reduction of the existing technology, the temperature in the single crystal furnace is relatively appropriately increased to a certain extent. The purpose is also to pull the single crystal with the increased second pulling speed and accelerate the flipping of the single crystal growth interface;

When the shoulder length of the second section of shoulder 2 is drawn to H2, the shoulder expansion step ends;

The shoulder length is the height of the shoulder. In the present invention, it represents the shortest distance from the top to the bottom of the shoulder, that is, the vertical distance. H2 is two-thirds of the overall shoulder length.

Example 2

S1: Temperature stabilization stage, during the temperature stabilization process, adjust the crucible position to the first position;

The crucible position is the crucible position. In the present invention, it represents the position where the molten raw material liquid level in the crucible is at a certain distance from the bottom of the flow guide tube. The first position is the position where the liquid level in the crucible is 30mm away from the bottom of the flow guide tube.

Compared with the crucible position in the temperature stabilization stage in the existing technology, the distance is reduced by a certain distance, which can change the crystallization area and the shape of the shoulder. At the same time, it speeds up the interface flip of single crystal growth so that it can complete the interface flip in the shoulder expansion stage. , improve the crystallization rate of single crystal;

After adjusting the crucible position to the first position, it remains stationary until the temperature stabilization phase is completed and the next shoulder expansion phase is entered.

S2: Shoulder expansion stage, which includes the first shoulder expansion stage and the second shoulder expansion stage. It should be noted that the lower the crystal pulling speed or the smaller the longitudinal temperature gradient, the greater the degree of the single crystal growth interface convex to the liquid surface; the crystal The higher the pulling speed or the greater the longitudinal temperature gradient, the greater the concaveness of the single crystal growth interface toward the liquid surface, where,

S21: In the first shoulder expansion stage, adjust the crucible position from the first position to the second position, and then use the first drawing speed to draw the first shoulder section 1, and reduce the temperature during the drawing process;

The meaning of the crucible position is consistent with that in S1. The second position of the crucible position is 25mm from the liquid level in the crucible to the bottom of the guide tube;

When the crucible position moves from the first position to the second position, start pulling the single crystal, and use the first pulling speed to pull the first section 1, where the first pulling speed is 65mm/h;

In the first shoulder expansion stage, the crystal pulling temperature needs to be lowered. The cooling method used in the present invention is to reduce the power of the heater to cool down during the drawing process, where,

The first power reduction is 17kw; compared with the existing technology, more heater power is reduced, resulting in a lower temperature in the single crystal furnace;

When the shoulder length of the first section of shoulder 1 is drawn to H1, the first shoulder expansion stage ends;

The shoulder length is the height of the shoulder. In the present invention, it represents the shortest distance from the top to the bottom of the shoulder, that is, the vertical distance. H1 is one-half of the overall shoulder length;

S22: In the second shoulder expansion stage, the crucible position remains unchanged, change the first pulling speed to the second pulling speed, use the second pulling speed to continue drawing the second shoulder 2 at the bottom of the first shoulder, and During the drawing process, the temperature continues to be lowered and the shoulder expansion is completed;

The meaning of the crucible position is consistent with that in S1. In the second shoulder expansion stage, the second position of the crucible position remains unchanged, which is consistent with step S21. The liquid level in the crucible is 25mm from the bottom of the guide tube;

Continue to draw the second shoulder 2 at the bottom of the first shoulder 1, and use the second drawing speed to draw the second shoulder 2, where the second drawing speed is higher than the first drawing speed and is 90mm/h;

Compared with the existing technology, increasing the pulling speed during the second shoulder expansion process can change the shape of the shoulder, so that an included angle is formed between the first shoulder 1 and the second shoulder 2. The included angle is generally 150- 180° (excluding 180°), and can accelerate the interface flip in the second shoulder 2, flip the growth interface of the single crystal over, and change it from convex to the liquid surface to concave to the liquid surface, thereby improving the crystallization of the single crystal. Rate;

In the second shoulder expansion stage, the crystal pulling temperature needs to be lowered. The cooling method used in the present invention is to reduce the power of the heater to cool down during the drawing process, where,

Continue to reduce the power of the heater after reducing the power in the first shoulder expansion stage, so as to cool down again, in which the second power reduction is 3kw;

Compared with the power reduction of the existing technology, the temperature in the single crystal furnace is relatively appropriately increased to a certain extent. The purpose is also to pull the single crystal with the increased second pulling speed and accelerate the flipping of the single crystal growth interface;

When the shoulder length of the second section of shoulder 2 is drawn to H2, the shoulder expansion step ends;

The shoulder length is the height of the shoulder. In the present invention, it represents the shortest distance from the top to the bottom of the shoulder, that is, the vertical distance. H2 is one-half of the overall shoulder length.

Example 3

S1: Temperature stabilization stage, during the temperature stabilization process, adjust the crucible position to the first position;

The crucible position is the crucible position. In the present invention, it represents the position where the molten raw material liquid level in the crucible is at a certain distance from the bottom of the guide tube. The first position is the position where the liquid level in the crucible is 20-30mm away from the bottom of the guide tube. Preferably, the liquid level in the crucible is 24mm from the bottom of the guide tube;

Compared with the crucible position in the temperature stabilizing stage in the existing technology, it can change the crystallization area and the shoulder shape, and at the same time accelerate the interface flip of the single crystal growth, so that it can complete the interface flip during the shoulder expansion stage, improving the single crystal's Crystallization rate;

After adjusting the crucible position to the first position, it remains stationary until the temperature stabilization phase is completed and the next shoulder expansion phase is entered.

S2: Shoulder expansion stage, which includes the first shoulder expansion stage and the second shoulder expansion stage. It should be noted that the lower the crystal pulling speed or the smaller the longitudinal temperature gradient, the greater the degree of the single crystal growth interface convex to the liquid surface; the crystal The higher the pulling speed or the greater the longitudinal temperature gradient, the greater the concaveness of the single crystal growth interface toward the liquid surface, where,

S21: In the first shoulder expansion stage, adjust the crucible position from the first position to the second position, and then use the first drawing speed to draw the first shoulder section 1, and reduce the temperature during the drawing process;

The meaning of the crucible position is consistent with that in S1. The second position of the crucible position is where the liquid level in the crucible is 15-25mm from the bottom of the flow guide tube, preferably 20mm between the liquid level in the crucible and the bottom of the flow guide tube;

When the crucible moves from the first position to the second position, start pulling the single crystal, and use the first pulling speed to pull the first section 1, where the first pulling speed is 60mm/h;

Compared with the existing technology, the drawing speed in the first shoulder expansion stage changes slightly and is basically unchanged, and the first shoulder 1 is drawn normally;

In the first shoulder expansion stage, the crystal pulling temperature needs to be lowered. The cooling method used in the present invention is to reduce the power of the heater to cool down during the drawing process, where,

The first power reduction is 12kw; compared with the existing technology, more heater power is reduced, resulting in a lower temperature in the single crystal furnace;

When the shoulder length of the first section of shoulder 1 is drawn to H1, the first shoulder expansion stage ends;

The shoulder length is the height of the shoulder. In the present invention, it represents the shortest distance from the top to the bottom of the shoulder, that is, the vertical distance. Generally, H1 is 40% of the overall shoulder length;

S22: In the second shoulder expansion stage, the crucible position remains unchanged, change the first pulling speed to the second pulling speed, use the second pulling speed to continue drawing the second shoulder 2 at the bottom of the first shoulder, and During the drawing process, the temperature continues to be lowered and the shoulder expansion is completed;

The crucible position has the same meaning as in S1. In the second shoulder expansion stage, the second position of the crucible position remains unchanged, consistent with step S21. The liquid level in the crucible is 20mm from the bottom of the guide tube;

Continue to draw the second shoulder 2 at the bottom of the first shoulder 1, and draw the second shoulder 2 using a second drawing speed, where the second drawing speed is higher than the first drawing speed, which is 80mm/h;

Compared with the existing technology, increasing the pulling speed during the second shoulder expansion process can change the shape of the shoulder, so that an included angle is formed between the first shoulder 1 and the second shoulder 2. The included angle is generally 150- 180° (excluding 180°), and can accelerate the interface flip in the second shoulder 2, flip the growth interface of the single crystal over, and change it from convex to the liquid surface to concave to the liquid surface, thereby improving the crystallization of the single crystal. Rate;

In the second shoulder expansion stage, the crystal pulling temperature needs to be lowered. The cooling method used in the present invention is to reduce the power of the heater to cool down during the drawing process, where,

Continue to reduce the power of the heater after reducing the power in the first shoulder expansion stage, so as to cool down again, in which the second power reduction is 5kw;

Compared with the power reduction of the existing technology, the temperature in the single crystal furnace is relatively appropriately increased to a certain extent. The purpose is also to pull the single crystal with the increased second pulling speed and accelerate the flipping of the single crystal growth interface;

When the shoulder length of the second section of shoulder 2 is drawn to H2, the shoulder expansion step ends;

The shoulder length is the height of the shoulder. In the present invention, it represents the shortest distance from the top to the bottom of the shoulder, that is, the vertical distance. H2 is 60% of the overall shoulder length.

The embodiments of the present invention have been described in detail above, but the contents are only preferred embodiments of the present invention and cannot be considered to limit the implementation scope of the present invention. All equivalent changes and improvements made within the scope of the present invention shall still fall within the scope of the patent of the present invention.

Claims (8)

1. A process for improving the early-stage crystallization rate of shoulder expansion and equal diameter of large-sized single crystals, including: In the temperature stabilization stage, the crucible position is adjusted to the first position during the temperature stabilization process; The shoulder expansion stage includes the first shoulder expansion stage and the second shoulder expansion stage, wherein, In the first shoulder expansion stage, the crucible position is adjusted from the first position to the second position, and then the first shoulder section is drawn using the first drawing speed, and the temperature is lowered during the drawing process; In the second shoulder expansion stage, the crucible position remains unchanged, the first pulling speed is changed to the second pulling speed, and the second pulling speed is used to continue drawing at the bottom of the first shoulder section. The second shoulder section continues to lower the temperature during the drawing process, and the shoulder expansion is completed. 2. A process for improving the early crystallization rate of large-size single crystal shoulder expansion and equal diameter according to claim 1, characterized in that: the first position is 20-30mm from the liquid level in the crucible to the guide tube. at. 3. A process for improving the shoulder expansion and equal-diameter pre-crystallization rate of large-sized single crystals according to claim 1 or 2, characterized in that: the second position is the distance between the liquid level in the crucible and the guide tube 15 -25mm. 4. A process for improving the initial crystal formation rate of shoulder expansion and equal diameter of large-sized single crystals according to claim 1, characterized in that the first pulling speed range is 50-65mm/h. 5. A process for improving large-size single crystal shoulder expansion and equal-diameter pre-crystallization rate according to claim 1 or 4, characterized in that: the second pulling speed is higher than the first pulling speed, and The range is 70-90mm/h. 6. A process for improving the initial crystallization rate of large-size single crystal shoulder expansion and equal diameter according to claim 1, characterized in that: in the first shoulder expansion stage, the power of the heater is reduced, so that during the pulling process Cooling is performed during the production process, in which the first power reduction range is 7-17kw. 7. A process for improving large-size single crystal shoulder expansion and equal diameter early crystallization rate according to claim 1 or 6, characterized in that: in the second shoulder expansion range, the power of the heater is continued to be reduced, Thus, the temperature is reduced, wherein the range of the second power reduction is 3-8kw. 8. A process for improving large-size single crystal shoulder expansion and equal-diameter pre-crystallization rate according to claim 1, characterized in that: the height of the first shoulder is H1, and the height of the second shoulder is H1. The height is H2, wherein the ratio range of H1:H2 is 1:1-2:1.