Crystal growing device

Abstract

The utility model discloses a crystal growing device, which comprises a crucible, the lifting device movably penetrates through the top of the crucible in the axis direction of the crucible; the growth mold comprises a reducing section, the reducing section comprises a first reducing section and a first expanding section, the first reducing section and the first expanding section are located in the crucible and adjacently arranged in the axis direction of the crucible, and the first reducing section and the first expanding section are each of a cylindrical structure and extend in the axis direction of the crucible; the first reducing section is provided with a first end close to the top wall of the crucible and a second end far away from the top wall, the inner diameter of the first reducing section is reduced from the first end to the second end, and the first expanding section is provided with a third end close to the top wall and a fourth end far away from the top wall; and the inner diameter of the first expanding section is increased from the third end to the fourth end. According to the crystal growing device disclosed by the embodiment of the utility model, crystal defects can be reduced while the crystal size is maintained.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of crystal growth. BACKGROUND

[0002] Silicon carbide is the representative of the third generation semiconductor material, compared with the traditional semiconductor material represented by Si and GaAs, silicon carbide has great advantages in working temperature, radiation resistance, breakdown voltage resistance and other performances, thereby having wide application in the fields of semiconductor, microelectronic power and the like. In recent years, the market size of silicon carbide substrate is large, and obtaining large-size silicon carbide substrate with excellent quality becomes the need of market development.

[0003] Liquid phase method for growing silicon carbide crystal is to put silicon raw material and rare metal into graphite crucible, raise the temperature in the graphite crucible to make the silicon raw material and rare metal melt, the silicon solution formed after melting can dissolve the carbon in graphite to form a silicon solution containing carbon; then the silicon carbide seed crystal is immersed into the silicon solution containing carbon, so that the carbon supersaturation state is obtained near the silicon carbide seed crystal, thereby growing silicon carbide single crystal on the silicon carbide seed crystal. Liquid phase method for growing crystal has the characteristics of fast crystal growth. However, the silicon carbide single crystal grown by traditional liquid phase method has many crystal defects such as voids and microtubes, which affects the quality of silicon carbide products.

[0004] Therefore, it is urgent to provide a crystal growth scheme which is beneficial to reduce crystal defects. UTILITY MODEL CONTENT

[0005] To solve at least one or more technical problems as mentioned above, the utility model provides a crystal growth device, include: crucible, pulling device, along the axis direction of the crucible movable through the top of the crucible, and growth mould, including variable diameter section, the variable diameter section includes the first reducing diameter section and first expanding diameter section that are adjacently arranged in the crucible and along the axis direction of the crucible, the first reducing diameter section and first expanding diameter section are all cylindrical structure and all extend along the axis direction of the crucible, the first reducing diameter section has the first end close to the top wall of the crucible and the second end away from the top wall, the inner diameter of the first reducing diameter section decreases from the first end to the second end, the first expanding diameter section has the third end close to the top wall and the fourth end away from the top wall, the inner diameter of the first expanding diameter section increases from the third end to the fourth end, the second end of the first reducing diameter section is connected with the third end of the first expanding diameter section and the inner diameter is equal, wherein the growth mould includes one variable diameter section or a plurality of variable diameter sections that are sequentially arranged along the axial direction of the crucible, the first end of the first reducing diameter section in the variable diameter section closest to the top wall is connected with the pulling device, in the case where the growth mould includes a plurality of variable diameter sections, the fourth end of the first expanding diameter section in one of any two adjacent variable diameter sections is connected with the first end of the first reducing diameter section in the other variable diameter section and the inner diameter is equal.

[0006] In some embodiments, each variable diameter section is a continuous cylindrical structure, and the growth mould as a whole is a continuous cylindrical structure; and the growth mould is an integrally formed structure.

[0007] In other embodiments, the connection between the first expanding diameter section and the first reducing diameter section in the same variable diameter section has a circular inner chamfer; and / or in the case where the growth mould includes a plurality of variable diameter sections, the connection between the first expanding diameter section in one of any two adjacent variable diameter sections and the first reducing diameter section in the other variable diameter section has a circular inner chamfer.

[0008] In yet other embodiments, the growth mould further includes a stress release section connected with the fourth end of the first expanding diameter section in the variable diameter section farthest away from the top wall.

[0009] In some embodiments, the stress release section comprises a second necked-down section and a second necked-up section arranged adjacently along the axial direction of the crucible, the second necked-down section and the second necked-up section are both cylindrical structures and both extend along the axial direction of the crucible, the second necked-down section has a fifth end close to the top wall and a sixth end away from the top wall, the inner diameter of the second necked-down section decreases from the fifth end to the sixth end, the second necked-up section has a seventh end close to the top wall and an eighth end away from the top wall, the inner diameter of the second necked-up section increases from the seventh end to the eighth end, the sixth end of the second necked-down section is connected with the seventh end of the second necked-up section and the inner diameters are equal, and the fifth end of the second necked-down section is connected with the fourth end of the first necked-up section in the variable-diameter section farthest away from the top wall.

[0010] In other embodiments, the connection between the fifth end of the second necked-down section and the fourth end of the first necked-up section in the variable-diameter section farthest away from the top wall has a circular inner chamfer; and the connection between the second necked-up section and the second necked-down section has a sharp-angled inner chamfer.

[0011] In yet other embodiments, the length of each of the first necked-down sections in the axial direction of the crucible is 5-10 mm; the first included angle between the extension direction of the inner wall of each of the first necked-down sections and the axial direction of the crucible is 10-70°; the length of each of the first necked-up sections in the axial direction of the crucible is 5-10 mm; the second included angle between the extension direction of the inner wall of each of the first necked-up sections and the axial direction of the crucible is 10-80°; and the sum of the angles of the first included angles corresponding to the first necked-down sections in the variable-diameter sections is 90°.

[0012] In some embodiments, the length of the second necked-down section in the axial direction of the crucible is 3-5 mm; the third included angle between the extension direction of the inner wall of the second necked-down section and the axial direction of the crucible is 10-80°; the length of the second necked-up section in the axial direction of the crucible is 1-3 mm; and the fourth included angle between the extension direction of the inner wall of the second necked-up section and the axial direction of the crucible is 10-80°.

[0013] In other embodiments, the crucible is a graphite crucible; and the crystal growth device further comprises an electrode connected with the graphite crucible for supplying electricity to the graphite crucible.

[0014] In yet some embodiments, the graphite crucible comprises a first graphite crucible body and a second graphite crucible body, the first graphite crucible body has a first cavity, a top of the first graphite crucible body has a through hole in communication with the first cavity, the pulling device is arranged in the through hole, a bottom of the first graphite crucible body has a first opening in communication with the first cavity, the second graphite crucible body has a second cavity, a top of the second graphite crucible body has a second opening in communication with the second cavity, the bottom of the first graphite crucible body is connected with the top of the second graphite crucible body, and the first opening is in communication with the second opening; the electrode comprises a first electrode and a second electrode, the first electrode is connected with the first graphite crucible body, the first electrode is used for electrifying the first graphite crucible body, the second electrode is connected with the second graphite crucible body, and the second electrode is used for electrifying the second graphite crucible body.

[0015] In some embodiments, the crystal growth device further comprises a separation component, which is annular or cylindrical, and the bottom of the first graphite crucible body is connected with the top of the second graphite crucible body through the separation component; the resistance value of the separation component is higher than the resistance values of the first graphite crucible body and the second graphite crucible body.

[0016] It can be known from the crystal growth device provided above that, in the crystal growth device, the growth mold comprising the variable-diameter section is arranged, so that the crystal can grow along the shape of the growth mold, and the first diameter-reducing section with a reduced inner diameter is arranged in the variable-diameter section, which can reduce the diameter of the crystal when the crystal grows along the first diameter-reducing section, so that the defects such as holes and microtubules at the edge of the crystal are reduced or eliminated, and the purpose of reducing the overall defects of the crystal is achieved. In addition, the first diameter-increasing section is arranged in the variable-diameter section, which can make the diameter of the crystal reach the required size. Therefore, in general, the crystal growth device can achieve the purpose of reducing the defects of the crystal while maintaining the diameter of the crystal by arranging the first diameter-reducing section and the first diameter-increasing section. BRIEF DESCRIPTION OF DRAWINGS

[0017] The above and other objects, features and advantages of the exemplary embodiments of the present application will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0018] Figure 1 A schematic view of a crystal growth device according to an embodiment of the present application is shown;

[0019] Figure 2a A front view of a growth mold comprising a plurality of variable-diameter sections according to an embodiment of the present application is shown.

[0020] Figure 2b A front view of a growth mold according to an embodiment of the present application is shown, in which the sum of the angles of the first and second included angles is 90°.

[0021] Figure 3 A front view of a growth mold according to an embodiment of the present application is shown, in which the sum of the angles of the first and second included angles is 90°. Figure 2a A perspective view of a growth mold according to an embodiment of the present application is shown.

[0022] Figure 4 A front view of a growth mold according to an embodiment of the present application is shown, in which the sum of the angles of the first and second included angles is 90°.

[0023] Figure 5 A schematic view of a crystal growth apparatus according to another embodiment of the present application is shown. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] It should be understood that the terms "comprise" and "include" used in the specification and claims of the present application indicate the presence of the described features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0026] It should also be understood that the terms used in the present application specification are only for the purpose of describing specific embodiments, and are not intended to limit the present application. As used in the specification and claims of the present application, the singular forms "a", "an" and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should be further understood that the term "and / or" used in the specification and claims of the present application means one or more of the associated listed items and all possible combinations thereof, and includes these combinations.

[0027] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0028] Figure 1 A schematic view of a crystal growth apparatus according to an embodiment of the present application is shown. As shown in FIG. 1, the crystal growth apparatus 100 includes a growth mold 110, a heater 120, a temperature controller 130, a temperature sensor 140, and a controller 150. Figure 1As shown, the crystal growth apparatus may include a crucible 110, a pulling device 120, and a growth mold, wherein the pulling device 120 is movably inserted through the top of the crucible 110 along the axial direction F. The crucible 110 has a cavity that can be used to accommodate silicon raw materials and the growth mold to form a space for crystal growth. In some embodiments, the top of the crucible 110 may have a through hole penetrating the top wall 111, so that the pulling device 120 can be movably inserted through the through hole along the axial direction F of the crucible 110. In other embodiments, the pulling device 120 may be a rod-shaped structure. In some embodiments, one end of the growth mold near the top wall 111 of the crucible 110 may be directly or indirectly connected to the pulling device 120, so that the growth mold can also move along the axial direction F of the crucible 110 under the action of the pulling device 120, thereby allowing the crystal to grow along the growth mold and to grow a corresponding crystal morphology according to the shape of the mold.

[0029] like Figure 1 As further shown in the illustration, the growth mold according to an embodiment of the present invention may include a variable diameter section 150, which may include a first narrowing section 130 and a first expanding section 140 located inside the crucible 110 and arranged adjacent to each other along the axial direction F of the crucible 110. Both the first narrowing section 130 and the first expanding section 140 may be cylindrical structures and both extend along the axial direction F of the crucible 110. In some embodiments, the variable diameter section 150 may be a continuous cylindrical structure. Here, continuity can mean an uninterrupted connection between the first narrowing section 130 and the first expanding section 140. A cylindrical structure refers to a hollow, three-dimensional structure with a certain height; the cross-sectional shape of the inner wall of the cylindrical structure may be circular, square, or polygonal, etc.

[0030] like Figure 1 As shown, the first narrowing section 130 may have a first end 131 near the top wall 111 of the crucible 110 and a second end 132 away from the top wall 111. The inner diameter of the first narrowing section 130 decreases from the first end 131 to the second end 132. The first expanding section 140 has a third end 141 near the top wall 111 and a fourth end 142 away from the top wall 111. The inner diameter of the first expanding section 140 increases from the third end 141 to the fourth end 142. The second end 132 of the first narrowing section 130 is connected to the third end 141 of the first expanding section 140 and has the same inner diameter. The top wall 111 of the crucible 110 may be the crucible wall through which the lifting device 120 penetrates the crucible 110. The decrease in the inner diameter of the first narrowing section 130 from the first end 131 to the second end 132 may be a gradual decrease. The increase in the inner diameter of the first expanding section 140 from the third end 141 to the fourth end 142 may be a gradual increase. In some embodiments, the inner diameter of the fourth end 142 may be, for example, 200 mm.

[0031] In some embodiments, the growth mold can include one variable-diameter section 150 or a plurality of variable-diameter sections 150 arranged in sequence along the axial direction of the crucible 110, and the first end 131 of the first reduced-diameter section 130 in the variable-diameter section 150 closest to the top wall 111 can be connected with the pulling device 120. The connection here can be direct or indirect. For example, in other embodiments, the pulling device 120 can include a pulling rod and a seed table connected with the bottom end of the pulling rod, the seed table can be used to arrange a seed crystal, and the variable-diameter section 150 closest to the top wall 111 can be directly connected with the seed table, so that the seed table is located between the pulling rod and the variable-diameter section closest to the top wall. In some embodiments, the growth mold can be a cylindrical structure with a side bottom surface as a whole, that is, the first end 131 of the first reduced-diameter section 130 in the variable-diameter section 150 closest to the top wall 111 has a bottom surface, which can be directly connected with the pulling device 120. In yet other embodiments, the seed crystal can be directly bonded to the bottom of the pulling device 120, and the variable-diameter section 150 closest to the top wall 111 in the growth mold can be connected with the seed crystal to achieve indirect connection of the growth mold with the pulling device 120.

[0032] In the case where the growth mold includes one variable-diameter section 150, the one variable-diameter section 150 is the variable-diameter section closest to the top wall 111. In the case where the growth mold includes a plurality of variable-diameter sections 150, since the plurality of variable-diameter sections 150 are connected in sequence along the axial direction F, the variable-diameter section 150 closest to the top wall 111 among the plurality of variable-diameter sections 150 is the variable-diameter section closest to the top wall 111.

[0033] In some embodiments, the periphery of the crucible 110 can be arranged with heating elements to control the temperature of crystal growth in the crucible 110. In other embodiments, the crucible 110 can be a graphite crucible; and the crystal growth device can further include electrodes connected with the graphite crucible for electrically connecting the graphite crucible. The number of electrodes can be two to connect the positive and negative poles of the power supply, respectively.

[0034] Since graphite can conduct electricity, in some embodiments of the present application, by directly connecting the graphite crucible to the power supply, the graphite crucible itself can be used as a heater to adjust the temperature in the graphite crucible. Compared with using a conventional radio frequency furnace as a heater to control the crystal growth conditions, and other heating methods such as arranging heating elements on the periphery of the crucible, according to the embodiments of the present application, the crucible itself is used as a resistor to achieve heating, which serves as the main source of heat for the thermal field in the crucible, which is conducive to improving the uniformity of the temperature field distribution in the crucible, thereby helping to avoid problems such as crystal diameter expansion cracking caused by uneven temperature field distribution during crystal growth.

[0035] The above is described in combination with Figure 1The crystal growth device according to the embodiments of the present application is exemplarily described, and it can be understood that, by setting the growth mold comprising the first diameter-reducing section and the first diameter-increasing section, and connecting the first end 131 of the first diameter-reducing section 130 in the variable-diameter section 150 closest to the top wall 111 with the pulling device 120, the crystal can first be diameter-reduced and then diameter-increased in the growth process, instead of first being diameter-increased and then diameter-reduced or not being diameter-changed. Compared with the crystal grown without diameter change, which may have defects, and the crystal grown by first being diameter-increased, which may have increased defects, the crystal grown by first being diameter-reduced in the embodiments of the present application can first reduce or eliminate the crystal defects, and then be diameter-increased to grow the crystal with reduced or eliminated defects to the required size, so that the risk of crystal defects can be effectively reduced or avoided.

[0036] It can also be understood that the above description is exemplary but not restrictive, for example, the growth mold can not be limited to only comprising one variable-diameter section in the drawings, and a plurality of variable-diameter sections can also be set according to needs. For the convenience of understanding, the growth mold will be exemplarily described below in combination with Figure 2a Figure 3 .

[0037] Figure 2a A front view of a growth mold comprising a plurality of variable-diameter sections according to an embodiment of the present application is shown. Figure 3 A perspective view of the growth mold shown in Figure 2a . In combination with Figure 2a and Figure 3 , the growth mold as a whole can be a continuous cylindrical structure. In other embodiments, the growth mold can be a one-piece structure.

[0038] As shown in Figure 2a and Figure 3 , the growth mold can comprise a plurality of variable-diameter sections (for example, the first variable-diameter section 150-1, the second variable-diameter section 150-1 and the third variable-diameter section 150-3 in the drawings), each of which can be a continuous cylindrical structure, and each of which can comprise a first diameter-reducing section and a first diameter-increasing section. For example, the first variable-diameter section 150-1 in the plurality of variable-diameter sections in the drawings can comprise a first diameter-reducing section 130-1 and a first diameter-increasing section 140-1, the second variable-diameter section 150-2 can comprise a first diameter-reducing section 130-2 and a first diameter-increasing section 140-2, and the third variable-diameter section 150-3 can comprise a first diameter-reducing section 130-3 and a first diameter-increasing section 140-3.

[0039] ​In the case that the growth mold comprises a plurality of variable-diameter sections, in any two adjacent variable-diameter sections, the fourth end of the first expanding section in one of the variable-diameter sections is connected to the first end of the first contracting section in the other of the variable-diameter sections, and the inner diameter of the fourth end is equal to that of the first end. Here, the "one of the variable-diameter sections" and the "the other of the variable-diameter sections" refer to one and the other of the two adjacent variable-diameter sections. For example, in the case of the adjacent first variable-diameter section 150-1 and the second variable-diameter section 150-2 in the figure, the fourth end 142-1 of the first expanding section 140-1 of the first variable-diameter section 150-1 is connected to the first end 131-2 of the first contracting section 130-2 of the second variable-diameter section 150-2, and the inner diameter of the fourth end 142-1 is equal to that of the first end 131-2, so that the connection between the fourth end 142-1 and the first end 131-2 can be naturally transitioned.

[0040] In some embodiments, in the case that the growth mold comprises a plurality of variable-diameter sections, in any two adjacent variable-diameter sections, the connection between the first expanding section in one of the variable-diameter sections and the first contracting section in the other of the variable-diameter sections can have a circular inner chamfer. For ease of illustration, still taking the adjacent first variable-diameter section 150-1 and the second variable-diameter section 150-2 in the figure as an example, the connection 220 (i.e., the connection between the fourth end 142-1 and the first end 131-2) between the first expanding section 140-1 of the first variable-diameter section 150-1 and the first contracting section 130-2 of the second variable-diameter section 150-2 can have a circular inner chamfer (see the circular dotted line in the figure). The circular inner chamfer herein refers to that the inner wall of the connection is arc-shaped or circular.

[0041] In other embodiments, in the same variable-diameter section, the connection between the first expanding section and the first contracting section can have a circular inner chamfer. For example, taking the first variable-diameter section 150-1 in the figure as an example, the connection 210 between the first expanding section 140-1 and the first contracting section 130-1 in the variable-diameter section can have a circular inner chamfer (see the circular dotted line in the figure). The connection between the first expanding section and the first contracting section is the connection between the third end of the first expanding section and the second end of the first contracting section.

[0042] In yet other embodiments, the length of each first contracting section in the axial direction of the crucible can be 5-10 mm. For example, the length of the first contracting section 130-1 in the axial direction F of the crucible in the figure can be 5-10 mm. In some embodiments, the length of the first contracting section in the axial direction of the crucible can also be understood as the height of the first contracting section. In other embodiments, the first included angle a between the extension direction of the inner wall of each first contracting section and the axial direction F of the crucible can be 10°-70°. In some embodiments, the extension direction of the inner wall of the first contracting section can be the direction of the first end of the first contracting section along the inner wall interface to the second end.

[0043] In some embodiments, the length of each first expanding section in the axial direction of the crucible can be 5-10 mm. For example, the length of the first expanding section 140-1 in the axial direction F of the crucible in the illustration can be 5-10 mm. In some embodiments, the length of the first expanding section in the axial direction of the crucible can also be understood as the height of the first expanding section. In other embodiments, the angle of the second included angle β between the extension direction of the inner wall of each first expanding section and the axial direction F of the crucible can be less than 90° (for example Figure 2a The angle of the second included angle β between the extension direction of the inner wall of each first expanding section and the axial direction F of the crucible is shown in the middle, of course, it can not be limited to this, for example, it can also be greater than 90°, or equal to 90°. In other words, the sum of the angles of the first included angle α and the second included angle β in the same variable diameter section can be 90°, or greater than 90°, or less than 90°.

[0044] For example, as shown in the middle Figure 2b The angle of the second included angle β between the extension direction of the inner wall of each first expanding section and the axial direction F of the crucible is shown in the middle, of course, it can not be limited to this, for example, it can also be greater than 90°, or equal to 90°. In other words, the sum of the angles of the first included angle α and the second included angle β in the same variable diameter section can be 90°, or greater than 90°, or less than 90°.

[0045] The above is described in combination with Figure 2a - Figure 3 The growth mold including a plurality of variable diameter sections is described exemplarily, it can be understood that a plurality of continuous variable diameter sections can facilitate rapid iterative growth of the seed crystal, and a plurality of first reducing sections can reduce the diameter multiple times during crystal growth, which is beneficial to remove more crystal defects to obtain a high-quality large-size crystal ingot. In some embodiments, the circular inner chamfer provided by the connection can effectively prevent the risk of crystal cracking caused by excessive curvature in a short distance.

[0046] It can also be understood that the above description and the shown in the figures are exemplary and not limiting, for example, the number of variable diameter sections can not be limited to three as shown in the figures, more or less can be set as needed. The length and angle of the first reduced diameter section and the first expanded diameter section in different variable diameter sections can not be limited to the same as shown in the figures, and can be set differently as needed. For example, the inner wall of the growth mold can be in the shape of a varying inner diameter, and the outer wall of the growth mold can not be limited to also changing as shown in the figures (for example, in the shape of a wave), in other embodiments, the outer wall of the growth mold can not be kept the same shape and angle as the inner wall, but can be set, for example, as a straight cylinder, that is, the outer diameter of the growth mold extending along the axial direction F can not change. For example, the growth mold can not be limited to only including variable diameter sections, and in yet other embodiments, the growth mold can also include a stress release section, which can be connected to the fourth end of the first expanded diameter section in the variable diameter section farthest from the top wall. The following will be described in an exemplary manner. Figure 4

[0047] Figure 4 A front view of a growth mold including a stress release section according to an embodiment of the present application is shown. As shown in the figure, the growth mold can include a plurality of variable diameter sections (for example, the first variable diameter section 150-1 and the second variable diameter section 150-2 shown in the figure) and a stress release section 400, wherein the first variable diameter section 150-1 can include a first reduced diameter section 130-1 and a first expanded diameter section 140-1, and the second variable diameter section 150-2 can include a first reduced diameter section 130-2 and a first expanded diameter section 140-2. In some embodiments, the growth mold shown in the figure can be integrally formed and can be a continuous cylindrical structure. Figure 4 Figure 4

[0048] Assuming that when the growth mold shown in the figure is set in the crucible, the top of the first variable diameter section 150-1 is directed towards the top wall of the crucible, then among the plurality of variable diameter sections, the second variable diameter section 150-2 is the variable diameter section farthest from the top wall compared to other variable diameter sections. In other embodiments, the stress release section 400 can include a second reduced diameter section 410 and a second expanded diameter section 420 adjacently arranged along the axial direction F of the crucible, which can both be cylindrical structures and extend along the axial direction F of the crucible. Further, the second reduced diameter section 410 can have a fifth end 411 close to the top wall and a sixth end 412 away from the top wall, and the inner diameter of the second reduced diameter section 410 decreases from the fifth end 411 to the sixth end 412. Here, the decrease can be gradual.

[0049] ​​​The second expanding section 420 can have a seventh end 421 close to the top wall and an eighth end 422 away from the top wall, and the inner diameter of the second expanding section 420 increases from the seventh end 421 to the eighth end 422. Here, the increase can be gradual. The sixth end 412 of the second reducing section 410 is connected to the seventh end 421 of the second expanding section 420 and has the same inner diameter, and the fifth end 411 of the second reducing section 410 is connected to the fourth end of the first expanding section in the variable diameter section farthest away from the top wall, for example, the fifth end 411 in the figure is connected to the fourth end 142-2 of the first expanding section 140-2 in the second variable diameter section 150-2.

[0050] As further shown in Figure 4 the fifth end 411 of the second reducing section 410 is connected to the fourth end of the first expanding section in the variable diameter section farthest away from the top wall, in some embodiments, the connection 430 can have a circular inner chamfer (see the dotted circle shown in the figure); and the connection 440 between the second expanding section 420 and the second reducing section 410 can have a sharp-angled inner chamfer (see the dotted circle shown in Figure 4 the figure). The sharp-angled inner chamfer refers to the inner wall of the connection being at a sharp angle.

[0051] Further, in some embodiments, the length of the second reducing section 410 in the axial direction F of the crucible can be 3-5 mm. In some embodiments, the length of the second reducing section 410 in the axial direction of the crucible can also be understood as the height of the second reducing section 410. In some embodiments, the length of the second expanding section 420 in the axial direction F of the crucible is 1-3 mm. In some embodiments, the length of the second expanding section 420 in the axial direction of the crucible can also be understood as the height of the second expanding section 420.

[0052] In some embodiments, the third included angle θ between the extension direction of the inner wall of the second reducing section 410 and the axial direction F of the crucible is 10°-80°, and the fourth included angle γ between the extension direction of the inner wall of the second expanding section 420 and the axial direction F of the crucible is 10°-80°. In some embodiments, the sum of the angles of the third included angle θ and the fourth included angle γ can be 90°, or less than 90°, or greater than 90°. In some embodiments, the extension direction of the inner wall of the second reducing section can be the direction of the fifth end along the inner wall interface to the sixth end of the second reducing section, and the extension direction of the inner wall of the second expanding section can be the direction of the seventh end along the inner wall interface to the eighth end of the second expanding section.

[0053] The above is described in combination with Figure 4The growth mold including the stress release section according to the embodiments of the present utility model is described exemplarily, and it can be understood that, in some embodiments, a circular inner chamfer is arranged at the connection between the stress release section 400 and the variable diameter section, which can alleviate the short distance curvature of the crystal, reduce the stress of the crystal at the connection, and reduce the risk of cracking of the crystal. When the crystal growth reaches a certain thickness, the inner stress of the crystal increases, and the connection 440 between the second expanding section 420 and the second reducing section 410 is arranged as a sharp angle type inner chamfer, which can instantaneously increase the curvature of the crystal at the connection, generate stress concentration, so that the crystal can be cut at the stress concentration area (i.e. the connection of the sharp angle type inner chamfer), so that the crystal cracks at this area and releases stress, so as to reduce the stress of the remaining position of the crystal, and reserve the high-quality large-size complete crystal ingot. It can also be understood that the above description and the shown in the figure are exemplary but not limited, for example, the variable diameter section can not be limited to two in the figure, and more or less can be arranged as needed.

[0054] Figure 5 A schematic diagram of a crystal growth device according to another embodiment of the present utility model is shown. As shown in the figure, the crystal growth device can include a crucible, a pulling device 120 and a growth mold 510 arranged in the crucible and extending along the axial direction F of the crucible, wherein the growth mold 510 can include one or more variable diameter sections 150 and a stress release section 400, which have been described in the foregoing in connection with any of the embodiments of the growth mold 510, and will not be repeated here. Figure 5 Figure 1 Figure 4 Any of the embodiments of the growth mold 510 have been described in the foregoing, and will not be repeated here.

[0055] In the present embodiment, the crucible can be a graphite crucible, as shown in the figure, which can include a first graphite crucible body 520 and a second graphite crucible body 530, wherein the first graphite crucible body 520 can have a first cavity 521, the top of the first graphite crucible body 520 can have a through hole 522 communicating with the first cavity 521, the pulling device 120 can be arranged in the through hole 522, and the bottom of the first graphite crucible body 520 has a first opening communicating with the first cavity 521. The first graphite crucible body 520 can be a cylindrical structure including a bottom surface as a top wall of the first graphite crucible body 520. The shape of the through hole 522 can be adapted to the shape of the pulling device 120, so that the pulling device 120 can move through the through hole 522. For example, in some embodiments, the pulling device 120 is in the shape of a round rod, and the through hole 522 can be a circular hole. In other embodiments, the pulling device 120 is in the shape of a square rod, i.e. its cross section is square or rectangular, and the through hole 522 can be a corresponding square or rectangular shape.

[0056] ​​The second graphite crucible body 530 can have a second cavity 531, and the top of the second graphite crucible body 530 can have a second opening in communication with the second cavity 531. The bottom of the first graphite crucible body 520 is connected to the top of the second graphite crucible body 530, and the first opening is in communication with the second opening. The second graphite crucible body 530 can be a bottom-surface cylinder structure, and the bottom surface serves as the bottom of the second graphite crucible body 530. The connection of the bottom of the first graphite crucible body 520 to the top of the second graphite crucible body 530 can be the connection of the bottom end of the crucible wall of the first graphite crucible body 520 to the top end of the crucible wall of the second graphite crucible body 530. The bottom of the first graphite crucible body 520 can be directly connected or indirectly connected to the top of the second graphite crucible body 530. The first opening in communication with the second opening can make the first cavity 521 and the second cavity 531 in communication to form a complete crystal growth chamber.

[0057] As shown in further detail in Figure 5 The crystal growth device can further include electrodes for supplying electricity to the graphite crucible. In some embodiments, the electrodes can include a first electrode 541 and a second electrode 542, wherein the first electrode 541 can be connected to the first graphite crucible body 520, and the first electrode 541 can be used to supply electricity to the first graphite crucible body 520. The second electrode 542 can be connected to the second graphite crucible body 530, and the second electrode 542 can be used to supply electricity to the second graphite crucible body 530. One end of the first electrode 541 can be electrically connected to the first graphite crucible body 520, and the other end of the first electrode 541 can be connected to a power supply to form an electricity supply circuit, thereby achieving the purpose of supplying electricity to the first graphite crucible body 520.

[0058] In other embodiments, the number of first electrodes 541 can be two, and each is connected to the positive and negative poles of the power supply. One end of the second electrode 542 can be electrically connected to the second graphite crucible body 530, and the other end of the second electrode 542 can be connected to a power supply to form an electricity supply circuit, thereby achieving the purpose of supplying electricity to the second graphite crucible body 530. In other embodiments, the number of second electrodes 542 can be two, and each is connected to the positive and negative poles of the power supply. In yet other embodiments, the first electrode 541 and the second electrode 542 can each be a graphite electrode.

[0059] Compared with only one crucible body, by providing the first graphite crucible body 520 and the second graphite crucible body 530, and providing the first electrode 541 and the second electrode 542 to supply electricity to the first graphite crucible body 520 and the second graphite crucible body 530, respectively, the temperature field in the first cavity and the second cavity can be independently adjusted, thereby being more conducive to adjusting the radial and transverse temperature gradients in the crystal growth chamber, and being more conducive to further improving the uniformity of the temperature field during crystal growth, and being easier to adjust a suitable temperature field that is conducive to uniform crystal growth, thereby reducing the risk of crystal cracking.

[0060] Furthermore, in some embodiments, the crystal growth apparatus may further include a separator 550, which may be an annular or cylindrical structure, wherein the bottom of the first graphite crucible body 520 is connected to the top of the second graphite crucible body 530 via the separator 550; wherein the resistance of the separator 550 is higher than the resistance of the first graphite crucible body 520 and the resistance of the second graphite crucible body 530. The annular structure described herein may be a hollow circular ring or a square ring, etc. Compared to the cylindrical structure, the annular structure has a smaller height and can be sheet-like. In another embodiment, the separator 550 may be a cylindrical structure without a bottom surface.

[0061] The dimensions of the partition member 550 can be adapted to the dimensions of the first graphite crucible body 520 and the second graphite crucible body 530. For example, in some embodiments, the thickness of the partition member 550 can be the same as the wall thickness of the crucible. In other words, when the wall thicknesses of the first graphite crucible body 520 and the second graphite crucible body 530 are the same, the thickness of the partition member 550 can be the same as the wall thicknesses of the first graphite crucible body 520 and the second graphite crucible body 530, and the inner diameter of the partition member 550 can be the same as the dimensions of the first opening and the second opening. In some embodiments, the wall thicknesses of the first graphite crucible body 520 and the second graphite crucible body 530 can be 10-25 mm.

[0062] In other embodiments, the resistance of the separator 550 may be greater than 200 ohms. In some embodiments, the resistance of the separator 550 may be more than 1,000 times the resistance of the first graphite crucible body 520 or the second graphite crucible body 530. In still other embodiments, the separator 550 may be a rigid felt ring.

[0063] The separator 550 not only connects the first graphite crucible body 520 and the second graphite crucible body 530 to form a closed crystal growth chamber, but also, because the resistance of the separator 550 is higher than that of the first graphite crucible body 520 and the second graphite crucible body 530, it can block the current between the first graphite crucible body 520 and the second graphite crucible body 530, thereby preventing arcing between the first graphite crucible body 520 and the second graphite crucible body 530.

[0064] The crystal growth apparatus according to embodiments of the present invention has been described above with reference to multiple embodiments. To facilitate understanding of the usage of the crystal growth apparatus according to embodiments of the present invention, the following will use... Figure 5 Taking the crystal growth apparatus shown in the figure as an example, the process of growing crystals using the crystal growth apparatus will be described exemplarily.

[0065] In some application scenarios, first, the silicon raw material with purity of 4N-5N (i.e., containing only 0.000001-0.00009% impurities) can be loaded in the second cavity 531 of the second graphite crucible body 530, and then the 4H spliced seed crystal wafer with a bias of 4° (i.e., 4 pieces of seed crystal are spliced by cutting at an angle of 4°, and the crystal growth is grown at an angle of 4°) and the growth mold are installed. Then, the crystal growth chamber is pumped to a pressure below 1x10-2mbar, the power of the first graphite crucible body 520 is adjusted to 20-25kw, and the power of the second graphite crucible body 530 is adjusted to 10-15kw. When the silicon raw material is in the process of melting and is not completely melted, the lifting device 120 is lifted so that the position of the seed crystal wafer is far away from the liquid surface of the silicon raw material. After the silicon raw material is heated to a molten state, the power of the first graphite crucible body 520 and the second graphite crucible body 530 is maintained to start preparing for crystal growth.

[0066] When the silicon raw material in the crystal growth device is completely melted, and the temperature of the silicon solution reaches 1850-2010℃, the seed crystal wafer with the growth mold is contacted with the molten silicon solution liquid surface, and the lifting device 120 starts to drive the seed crystal wafer to rise at a speed of 0.3-0.8mm / h to realize crystal lengthening and thickening.

[0067] As the crystal grows along the first diameter-reducing section, the diameter of the crystal decreases, the crystal defects decrease, and then the diameter of the crystal increases at the first diameter-increasing section to reach the diameter of 200mm consistent with the seed crystal wafer. In the case where the growth mold includes multiple variable-diameter sections, the process of reducing and increasing the diameter of the crystal is repeated multiple times to reduce the crystal defects multiple times. When the crystal growth reaches a certain thickness, the crystal growth is completed after reaching the stress release section.

[0068] In the case where the sharp-angle type inner chamfer is between the second diameter-reducing section and the second diameter-increasing section of the stress release section, the stress is gathered around the sharp-angle type chamfer, and when the crystal is cut, the cutting can be performed along the sharp-angle type chamfer, so that the stress is released at the sharp-angle type chamfer to protect the crystal in other regions, and a low-stress crystal ingot is obtained, which can be used as a first-generation high-quality large-size substrate for subsequent processing.

[0069] In summary, the crystal growth device of the embodiments of the present application can effectively reduce the crystal defects by reducing the diameter of the crystal during the crystal growth process, and can make the crystal reach the required size by increasing the diameter, so that the crystal defects can be reduced as a whole under the condition of maintaining the diameter of the crystal. In some embodiments, by providing the stress release section, a stress release point can be provided for the crystal, so that the crystal cracks along the stress release point, that is, the crystal can crack in the specified area without cracking from other positions during cutting, so that a high-quality large-size crystal ingot is reserved.

[0070] While several embodiments of the present application have been shown and described herein, it is to be understood that all such embodiments are merely illustrative of the present application. Numerous modifications, changes and adaptations will occur to those skilled in the art without departing from the spirit and scope of the present application. It should be understood that each of the embodiments described herein and illustrated in the drawings represents only a typical embodiment of the present application. Numerous additions, subtractions and modifications can be made to these described embodiments without departing from the scope of the present application. It is intended that all such modification fall within the scope of the present application. Accordingly, the appended claims are intended to cover all such modifications.

Claims

1. A crystal growing apparatus, characterized by comprising: The crystal growth device comprises: a crucible; a pulling device movably penetrating through a top of the crucible along an axial direction of the crucible; and a growth mold comprising a variable-diameter section, the variable-diameter section comprising a first necking section and a first expanding section located in the crucible and adjacently arranged along the axial direction of the crucible, the first necking section and the first expanding section are both in a cylindrical structure and both extend along the axial direction of the crucible, the first necking section has a first end close to a top wall of the crucible and a second end away from the top wall, an inner diameter of the first necking section decreases from the first end to the second end, the first expanding section has a third end close to the top wall and a fourth end away from the top wall, an inner diameter of the first expanding section increases from the third end to the fourth end, the second end of the first necking section is connected with the third end of the first expanding section and has an equal inner diameter. In a case where the growth mold comprises a plurality of the variable-diameter sections, the first end of the first necking section in the variable-diameter section closest to the top wall is connected with the pulling device, and in a case where the growth mold comprises a plurality of the variable-diameter sections, the fourth end of the first expanding section in one of the two adjacent variable-diameter sections is connected with the first end of the first necking section in the other of the two adjacent variable-diameter sections and has an equal inner diameter. Each of the variable-diameter sections is a continuous cylindrical structure, and the growth mold as a whole is a continuous cylindrical structure.

2. The crystal growing apparatus of claim 1, wherein The growth mold is an integrally formed structure. In one of the variable-diameter sections, a connection between the first expanding section and the first necking section has a circular inner chamfer.

3. The crystal growing apparatus of claim 1, wherein In a case where the growth mold comprises a plurality of the variable-diameter sections, a connection between the first expanding section in one of the two adjacent variable-diameter sections and the first necking section in the other of the two adjacent variable-diameter sections has a circular inner chamfer. The growth mold further comprises a stress release section connected with the fourth end of the first expanding section in the variable-diameter section farthest away from the top wall. The stress release section comprises a second necking section and a second expanding section adjacently arranged along the axial direction of the crucible, the second necking section and the second expanding section are both in a cylindrical structure and both extend along the axial direction of the crucible, the second necking section has a fifth end close to the top wall and a sixth end away from the top wall, an inner diameter of the second necking section decreases from the fifth end to the sixth end, the second expanding section has a seventh end close to the top wall and an eighth end away from the top wall, an inner diameter of the second expanding section increases from the seventh end to the eighth end, the sixth end of the second necking section is connected with the seventh end of the second expanding section and has an equal inner diameter, and the fifth end of the second necking section is connected with the fourth end of the first expanding section in the variable-diameter section farthest away from the top wall.

4. The crystal growing apparatus according to any one of claims 1 to 3, characterized by 6. The crystal growth device according to claim 5, wherein 5. The crystal growing apparatus of claim 4, wherein a connection between the fifth end of the second necking section and the fourth end of the first expanding section in the variable-diameter section farthest away from the top wall has a circular inner chamfer. ​ ​ The connection between the second diameter-increasing section and the second diameter-decreasing section has an acute-angle inner chamfer.

7. The crystal growing apparatus according to any one of claims 1 to 3, wherein each of the first diameter-decreasing sections has a length of 5 to 10 mm in the axial direction of the crucible, and an angle of a first included angle between an extension direction of an inner wall of each of the first diameter-decreasing sections and the axial direction of the crucible is 10° to 70°; each of the first diameter-increasing sections has a length of 5 to 10 mm in the axial direction of the crucible, and an angle of a second included angle between an extension direction of an inner wall of each of the first diameter-increasing sections and the axial direction of the crucible is 10° to 70°, and a sum of the angle of the first included angle corresponding to the first diameter-decreasing section in the diameter-changing section where each of the first diameter-increasing sections is located and the angle of the second included angle is 90°.

8. The crystal growing apparatus according to claim 5, wherein the second diameter-decreasing section has a length of 3 to 5 mm in the axial direction of the crucible, and an angle of a third included angle between an extension direction of an inner wall of the second diameter-decreasing section and the axial direction of the crucible is 10° to 80°; the second diameter-increasing section has a length of 1 to 3 mm in the axial direction of the crucible, and an angle of a fourth included angle between an extension direction of an inner wall of the second diameter-increasing section and the axial direction of the crucible is 10° to 80°.

9. The crystal growing apparatus of claim 1, wherein the crucible is a graphite crucible; and the crystal growing apparatus further comprises: an electrode connected to the graphite crucible for applying electricity to the graphite crucible.

10. The crystal growing apparatus according to claim 9, wherein the graphite crucible comprises a first graphite crucible body and a second graphite crucible body, the first graphite crucible body has a first cavity, a top portion of the first graphite crucible body has a through hole communicating with the first cavity, the pulling device is arranged in the through hole, a bottom portion of the first graphite crucible body has a first opening communicating with the first cavity, the second graphite crucible body has a second cavity, a top portion of the second graphite crucible body has a second opening communicating with the second cavity, the bottom portion of the first graphite crucible body is connected to the top portion of the second graphite crucible body, and the first opening communicates with the second opening; the electrode comprises a first electrode and a second electrode, the first electrode is connected to the first graphite crucible body for applying electricity to the first graphite crucible body, the second electrode is connected to the second graphite crucible body for applying electricity to the second graphite crucible body.

11. The crystal growing apparatus of claim 10, wherein The crystal growing apparatus further comprises: a separation component in a ring structure or a cylindrical structure, the bottom portion of the first graphite crucible body is connected to the top portion of the second graphite crucible body through the separation component, and a resistance value of the separation component is higher than resistance values of the first graphite crucible body and the second graphite crucible body.

Images