Apparatus and method for improving crystal morphology growth

Abstract

The application provides a growth device and method for improving crystal morphology, and relates to the field of silicon carbide crystal growth. The growth device and the matched growth method selectively install a flow guide block with a specific shape of a gas phase outlet on the top of a crucible body, and set a translation mechanism to drive the crucible cover with a seed crystal to reciprocate linearly above the gas phase outlet. According to the difference between the shape of the gas phase outlet and the seed crystal movement rate, the growth surface of the crystal will present different morphologies. Therefore, the scanning type of the crystal growth mode can weaken the dependence of the crystal morphology and quality on the thermal field, accurately control the morphology of the crystal, and reduce the internal stress and dislocation defects of the crystal.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of silicon carbide crystal growth, in particular to a growth device and method for improving crystal morphology. BACKGROUND

[0002] The physical vapor transport method (i.e. PVT method) is a common method for growing silicon carbide single crystals. In the prior art, the crystal growth requires a high temperature of more than 2,000 degrees in the furnace, and the morphology and quality of the crystal are highly dependent on the thermal field. However, due to the non-uniform thermal field caused by heat conduction, the supersaturation of the crystal growth gas is different at different positions, making it difficult to control the crystal morphology, internal stress and dislocation. SUMMARY

[0003] The present application aims to provide a growth device and method for improving crystal morphology, which can weaken the dependence of the crystal morphology and quality on the thermal field, accurately control the morphology of the crystal, and reduce the internal stress and dislocation defects of the crystal.

[0004] The embodiments of the present application can be implemented as follows:

[0005] In a first aspect, the present application provides a growth device for improving crystal morphology, comprising:

[0006] a crystal growth furnace body;

[0007] a crucible body located in the crystal growth furnace body for containing silicon carbide powder;

[0008] a plurality of flow guide blocks, which are alternatively detachably connected to the top of the crucible body, each of the flow guide blocks is provided with a gas phase outlet, each of the gas phase outlets is in the shape of a strip and extends along a first direction, and the width of the middle and both ends of each of the gas phase outlets is different in size;

[0009] a heater located in the crystal growth furnace body and arranged around the crucible body;

[0010] a crucible cover located in the crystal growth furnace body and provided with a seed crystal;

[0011] a translation mechanism connected to the crucible cover for driving the crucible cover to reciprocate along a second direction at a preset speed, so that the seed crystal reciprocates above the gas phase outlet along the second direction;

[0012] wherein the second direction is perpendicular to the first direction.

[0013] In an optional embodiment, the number of the flow guide blocks is three, the gas phase outlets on the three flow guide blocks are respectively a first outlet, a second outlet and a third outlet, the width of the middle part of the first outlet is equal to the width of the two ends, the width of the middle part of the second outlet is greater than the width of the two ends, and the width of the middle part of the third outlet is less than the width of the two ends.

[0014] In an optional embodiment, the projection of the gas phase outlet and the seed crystal on a horizontal plane partially overlaps, and the two ends of the projection of the gas phase outlet are located outside the projection of the seed crystal.

[0015] In an optional embodiment, the translation mechanism comprises a translation shaft and a power source connected in transmission, the translation shaft is arranged through the body of the crystal growth furnace and can reciprocate in a second direction at a preset speed under the drive of the power source, the power source is located outside the body of the crystal growth furnace, and the crucible cover is fixedly connected to the translation shaft.

[0016] In an optional embodiment, the translation mechanism further comprises two mounting blocks, the two mounting blocks are respectively mounted to opposite sides of the outer wall of the body of the crystal growth furnace, a linear bearing is arranged in each of the two mounting blocks, and the translation shaft is arranged in the body of the crystal growth furnace through the two linear bearings and slides in the second direction.

[0017] In an optional embodiment, the outer wall of each of the two mounting blocks is wound with a water-cooling pipe.

[0018] In an optional embodiment, the two linear bearings are respectively arranged at the end portions of the two mounting blocks away from the body of the crystal growth furnace.

[0019] In an optional embodiment, the top of the crucible body is provided with an annular polysilicon groove, and the gas phase outlet, the space below the crucible cover and the inner cavity of the polysilicon groove are sequentially communicated.

[0020] In an optional embodiment, the inner wall of the gas phase outlet is provided with a tantalum plating layer, and the tantalum plating layer extends inwardly to the inner wall of the crucible body.

[0021] In a second aspect, the present application provides a growth method for improving the morphology of crystals, based on the growth device for improving the morphology of crystals according to any one of the preceding embodiments, comprising:

[0022] After the silicon carbide powder is filled, one of the flow guide blocks is connected to the top of the crucible body;

[0023] The heater is started to make the silicon carbide powder sublimate to form a crystal growth gas phase and flow out from the gas phase outlet;

[0024] The translation mechanism drives the crucible cover to reciprocate along the second direction at a preset speed, so that the seed crystal passes above the gas phase outlet along the second direction, and the crystal growth gas phase is crystallized on the seed crystal.

[0025] The growth device and method for improving crystal morphology provided by the embodiments of the present application have the following beneficial effects:

[0026] By selectively installing a flow guide block with a specific shape of gas phase outlet on the top of the crucible body, and setting a translation mechanism to drive the crucible cover to reciprocate linearly above the gas phase outlet with the seed crystal, the crystal growth gas phase flowing out of the gas phase outlet can be crystallized on the seed crystal to form a silicon carbide crystal. According to the shape of the gas phase outlet and the moving speed of the seed crystal, the growth surface of the crystal will present different morphologies. Therefore, this scanning type of crystal growth method can weaken the dependence of the crystal morphology and quality on the thermal field, accurately control the morphology of the crystal, and reduce the internal stress and dislocation defects of the crystal. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0028] Figure 1 The structure diagram of the growth device for improving crystal morphology provided by the embodiments of the present application is shown in the figure.

[0029] Figure 2 The crystal morphology diagram corresponding to the first outlet of the embodiments of the present application is shown in the figure.

[0030] Figure 3 The crystal morphology diagram corresponding to the second outlet of the embodiments of the present application is shown in the figure.

[0031] Figure 4 The crystal morphology diagram corresponding to the third outlet of the embodiments of the present application is shown in the figure.

[0032] Figure 5 The relative position diagram between the seed crystal and the gas phase outlet when the seed crystal is in the first limit position provided by the embodiments of the present application is shown in the figure.

[0033] Figure 6 The relative position diagram between the seed crystal and the gas phase outlet when the seed crystal is in the middle position provided by the embodiments of the present application is shown in the figure.

[0034] Figure 7 The relative position diagram between the seed crystal and the gas phase outlet when the seed crystal is in the second limit position provided by the embodiments of the present application is shown in the figure.

[0035] Icon: 100-long crystal furnace body; 200-crucible body; 210-flow guide block; 212-first outlet; 214-second outlet; 216-third outlet; 220-tantalum plating layer; 300-heater; 400-crucible cover; 410-seed crystal; 500-translation mechanism; 510-translation shaft; 520-power source; 530-mounting block; 532-linear bearing; 540-water-cooled pipe; 600-polycrystal tank; 700-silicon carbide powder. DETAILED DESCRIPTION

[0036] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor fall within the scope of protection of the present application.

[0038] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0039] In the description of the present application, it should be noted that if the terms "upper", "lower", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of the present application is usually placed, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the present application.

[0040] In addition, if the terms "first", "second" and the like appear, they are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0041] It should be noted that the features in the embodiments of the present application can be combined with each other without conflict.

[0042] Please refer to Figure 1This invention provides a growth apparatus for improving crystal morphology, comprising a crystal growth furnace body 100, a crucible body 200, multiple flow guide blocks 210, a heater 300, a crucible cover 400, and a translation mechanism 500. The crucible body 200 is located within the crystal growth furnace body 100 and is used to hold silicon carbide powder 700. One of the multiple flow guide blocks 210 is detachably connected to the top of the crucible body 200. Each flow guide block 210 is provided with a gas phase outlet, each gas phase outlet being elongated and extending along a first direction X, with the width of the middle and both ends of each gas phase outlet differing. The heater 300 is located within the crystal growth furnace body 100 and is arranged around the crucible body 200. The crucible cover 400 is located within the crystal growth furnace body 100 and is provided with a seed crystal 410. The translation mechanism 500 is connected to the crucible cover 400 and is used to drive the crucible cover 400 to reciprocate along the second direction Y at a preset speed, so that the seed crystal 410 reciprocates above the gas phase outlet along the second direction Y. The second direction Y is perpendicular to the first direction X.

[0043] By selectively installing a flow guide block 210 with a specific shape of gas phase outlet on the top of the crucible body 200, and setting a translation mechanism 500 to drive the crucible cover 400 to reciprocate linearly above the gas phase outlet, the growth gas phase flowing out of the gas phase outlet crystallizes on the seed crystal 410 to form silicon carbide crystals. Depending on the shape of the gas phase outlet and the movement rate of the seed crystal, the growth surface of the crystal will exhibit different morphologies. Therefore, this scanning crystal growth method can weaken the dependence of crystal morphology and quality on the thermal field, precisely control the crystal morphology, and reduce defects such as internal stress and dislocations in the crystal.

[0044] In this embodiment, please refer to Figure 2 , Figure 3 and Figure 4 There are three flow guide blocks 210, and the gas phase outlets on the three flow guide blocks 210 are the first outlet 212, the second outlet 214 and the third outlet 216, respectively.

[0045] The width of the middle part of the first outlet 212 is equal to the width of both ends (i.e., along the first direction X, the width of the first outlet 212 remains unchanged from the middle to both ends), used to form crystals with planar growth surfaces (such as...). Figure 2 As shown, the growth surface at the bottom of the crystal is planar. The width of the middle and both ends of the first outlet 212 is equal, which makes the flow rate of the crystal growth gas phase flowing out from the middle and both ends the same. Thus, in the first direction X, the crystal growth rate of the middle and edge of the seed crystal 410 is consistent, so a crystal with a planar growth surface can be obtained.

[0046] The width of the middle part of the second outlet 214 is greater than the width at both ends (i.e., along the first direction X, the width of the second outlet 214 gradually decreases from the middle to both ends), which is used to form crystals with convex growth surfaces (such as...). Figure 3As shown, the growth surface of the crystal bottom is convex. The width of the middle part of the second outlet 214 is greater than the width of the two ends, which can make the flow of the crystal growth gas from the middle part greater than the flow of the crystal growth gas from the two ends, so that in the first direction X, the crystal growth rate of the middle part of the seed crystal 410 is greater than the crystal growth rate of the edge of the seed crystal 410, and thus a crystal with a convex growth surface can be obtained.

[0047] The width of the middle part of the third outlet 216 is less than the width of the two ends (i.e. the width of the middle part of the third outlet 216 gradually increases to the two ends along the first direction X), which is used to form a crystal with a concave growth surface (as shown in Figure 4 As shown, the growth surface of the crystal bottom is concave. The width of the middle part of the third outlet 216 is less than the width of the two ends, which can make the flow of the crystal growth gas from the middle part less than the flow of the crystal growth gas from the two ends, so that in the first direction X, the crystal growth rate of the middle part of the seed crystal 410 is less than the crystal growth rate of the edge of the seed crystal 410, and thus a crystal with a concave growth surface can be obtained.

[0048] In order to delay the corrosion of the crystal growth gas to the gas phase outlet, avoid the increase of the carbon source, and reduce the carbon inclusion of the crystal, in the embodiment, a tantalum plating layer 220 is arranged on the inner wall of the gas phase outlet, and the tantalum plating layer 220 extends inwardly to the inner wall of the crucible body 200 to protect the gas phase outlet and the partial inner wall of the crucible body 200 adjacent to the gas phase outlet.

[0049] The projection of the gas phase outlet and the seed crystal 410 at any position on the horizontal plane partially overlaps, and the two ends of the projection of the gas phase outlet are located outside the projection of the seed crystal 410. Please refer to Figure 5 、 Figure 6 and Figure 7 The three figures respectively show the relative position relationship between the seed crystal 410 and the gas phase outlet (the gas phase outlet in the figure is taken as an example of the first outlet 212) when the seed crystal 410 is in the first limit position, the middle position and the second limit position. It can be seen that the projections of the seed crystal 410 and the gas phase outlet on the horizontal plane at the three positions satisfy the condition. Such arrangement can ensure that the crystal growth gas flowing out of the gas phase outlet can reach every region of the seed crystal 410, while minimizing the cross-sectional area of the crystal growth gas leakage (overflowing outside the seed crystal 410), thereby reducing the waste of silicon carbide powder 700 and improving the crystal growth efficiency.

[0050] Please refer to Figure 1In order to avoid the influence of the leaked crystal growth gas phase on the maintenance of the equipment, in the embodiment, the top of the crucible body 200 is provided with an annular polycrystal groove 600, the gas phase outlet, the space below the crucible cover 400 (i.e. the space surrounded by the crucible cover 400 and the gap between the upper surface of the flow guide block 210 and the crucible cover 400) and the inner cavity of the polycrystal groove 600 are sequentially communicated, and the inner side wall bottom of the polycrystal groove 600 is slidingly sealed with the top wall of the crucible cover 400. In this way, the leaked crystal growth gas phase can flow into the polycrystal groove 600 as much as possible and accumulate in the polycrystal groove 600 to form polycrystals, and will not flow to the crystal growth furnace body 100 in large quantities to affect the maintenance of the crystal growth furnace body 100.

[0051] The translation mechanism 500 can adopt different structures as required. In the embodiment, please refer to Figure 1 The translation mechanism 500 includes a translation shaft 510 and a power source 520 connected in transmission. The translation shaft 510 penetrates through the crystal growth furnace body 100 and can reciprocate along the second direction Y at a preset speed under the drive of the power source 520. The crucible cover 400 is fixedly connected to the translation shaft 510, so as to drive the seed crystal 410 to reciprocate along the second direction Y at a preset speed under the drive of the translation shaft 510.

[0052] In detail, in order to improve the stability and reliability of the movement of the translation shaft 510, in the embodiment, the translation mechanism 500 further includes two mounting blocks 530. The two mounting blocks 530 are respectively mounted on the opposite sides of the outer wall of the crystal growth furnace body 100. Linear bearings 532 are arranged in the two mounting blocks 530. The translation shaft 510 is slidingly arranged in the crystal growth furnace body 100 along the second direction Y through the two linear bearings 532.

[0053] Since the temperature that can be withstood by the linear bearing 532 is limited, in the embodiment, the two linear bearings 532 are respectively arranged at the ends of the two mounting blocks 530 away from the crystal growth furnace body 100. In this way, the working environment temperature of the linear bearing 532 can be reduced. Meanwhile, the outer walls of the two mounting blocks 530 are wound with water cooling pipes 540. The inlets and outlets of the water cooling pipes 540 are connected to external cold water, which can reduce the temperature of the mounting blocks 530, and further reduce the working environment temperature of the linear bearing 532, so as to ensure the working stability and prolong the service life of the linear bearing 532.

[0054] The power source 520 can adopt different structures, including but not limited to a linear motor, an oil cylinder and the like. An output shaft of the power source 520 is connected to any one end of the translation shaft 510, for providing power for the translation shaft 510.

[0055] The growth method corresponding to the above-mentioned growth device for improving the crystal morphology includes the following steps:

[0056] Step 1: after the silicon carbide powder 700 is loaded, one of the flow guides 210 is selected to be connected to the top of the crucible body 200. The selection of the flow guide 210 is determined according to the required crystal morphology.

[0057] In detail, if a crystal with a flat growth surface is required to be prepared, the flow guide 210 where the first outlet 212 is located is selected (see Figure 2 ), and the seed crystal 410 needs to be reciprocated at a constant speed along the second direction Y, that is, the speed when the vapor phase outlet corresponds to the central region of the seed crystal 410 is equal to the speed when the vapor phase outlet corresponds to the two side regions of the seed crystal 410 (the region where the seed crystal 410 is located can be divided into three regions along the second direction Y, that is, one side region, a middle region and the other side region, and the one side region and the other side region are collectively referred to as the two side regions).

[0058] If a crystal with a convex growth surface is required to be prepared, the flow guide 210 where the second outlet 214 is located is selected (see Figure 3 ), and the seed crystal 410 needs to be reciprocated at a variable speed along the second direction Y, wherein the speed when the vapor phase outlet corresponds to the middle region of the seed crystal 410 is less than the speed when the vapor phase outlet corresponds to the two side regions of the seed crystal 410.

[0059] If a crystal with a concave growth surface is required to be prepared, the flow guide 210 where the third outlet 216 is located is selected (see Figure 4 ), and the seed crystal 410 needs to be reciprocated at a variable speed along the second direction Y, wherein the speed when the vapor phase outlet corresponds to the middle region of the seed crystal 410 is greater than the speed when the vapor phase outlet corresponds to the two side regions of the seed crystal 410.

[0060] Step 2: start the heater 300 to make the silicon carbide powder 700 sublimate to form a crystal growth vapor phase and flow out from the vapor phase outlet.

[0061] Step 3: the translation mechanism 500 drives the crucible cover 400 to reciprocate along the second direction Y at a preset speed, so that the seed crystal 410 reciprocates above the vapor phase outlet along the second direction Y, so that the crystal growth vapor phase flowing out from the vapor phase outlet crystallizes on the seed crystal 410 to form a silicon carbide crystal.

[0062] The above growth method can be used to prepare a crystal with a required morphology, and the prepared crystal has the characteristics of good internal stress and few defects.

[0063] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A growth apparatus for improving crystal morphology, characterized in that, The application relates to a long crystal furnace body (100), a crucible body (200) located in the long crystal furnace body (100) and used for containing silicon carbide powder (700), a plurality of flow guide blocks (210) which are alternatively detachably connected to the top of the crucible body (200), each of the flow guide blocks (210) is provided with a gas phase outlet, each of the gas phase outlets is in a strip shape and extends along a first direction, and the width of the middle part and the two ends of each of the gas phase outlets is different, a heater (300) located in the long crystal furnace body (100) and arranged around the crucible body (200), a crucible cover (400) located in the long crystal furnace body (100) and provided with a seed crystal (410), a translation mechanism (500) connected with the crucible cover (400) and used for driving the crucible cover (400) to reciprocate along a second direction at a preset speed, so that the seed crystal (410) reciprocates above the gas phase outlet along the second direction, wherein the second direction is perpendicular to the first direction, the number of the flow guide blocks (210) is three, the gas phase outlets on the three flow guide blocks (210) are respectively a first outlet (212), a second outlet (214) and a third outlet (216), the width of the middle part of the first outlet (212) is equal to the width of the two ends, the width of the middle part of the second outlet (214) is greater than the width of the two ends, and the width of the middle part of the third outlet (216) is less than the width of the two ends, the projection of the gas phase outlet and the projection of the seed crystal (410) on a horizontal plane are partially coincident, and the two ends of the projection of the gas phase outlet are located outside the projection of the seed crystal (410), the translation mechanism (500) comprises a translation shaft (510) and a power source (520) in transmission connection, the translation shaft (510) penetrates the long crystal furnace body (100) and can reciprocate along the second direction at a preset speed under the drive of the power source (520), the power source (520) is located outside the long crystal furnace body (100), and the crucible cover (400) is fixedly connected to the translation shaft (510), the translation mechanism (500) further comprises two mounting blocks (530), the two mounting blocks (530) are respectively mounted to the opposite sides of the outer wall of the long crystal furnace body (100), linear bearings (532) are arranged in the two mounting blocks (530), and the translation shaft (510) is slidably arranged in the long crystal furnace body (100) along the second direction through the two linear bearings (532), the outer walls of the two mounting blocks (530) are wound with water cooling pipes (540), and the two linear bearings (532) are respectively arranged at the end parts of the two mounting blocks (530) away from the long crystal furnace body (100). ​ ​ ​ ​ ​ ​ ​ ​ 2. The apparatus for improving the morphology of crystal growth according to claim 1, wherein, ​ 3. The apparatus for improving the morphology of crystal growth according to claim 1, wherein, ​ 4. The apparatus for improving the morphology of crystal growth according to claim 3, wherein ​ 5. The apparatus for improving the morphology of crystal growth according to claim 4, wherein ​ 6. The apparatus for improving the morphology of crystal growth according to claim 4, wherein ​ 7. The apparatus for improving the morphology of crystal growth according to claim 1, wherein The top of the crucible body (200) is provided with an annular polycrystal groove (600), and the gas phase outlet, the space below the crucible cover (400) and the inner cavity of the polycrystal groove (600) are sequentially communicated.

8. The apparatus for improving the morphology of crystal growth according to claim 1, wherein, The inner wall of the gas phase outlet is provided with a tantalum plating layer (220) which extends inwardly to the inner wall of the crucible body (200).

9. A method for improving the morphology of a crystal grown by a device for improving the morphology of a crystal according to any one of claims 1 to 8, characterized in that The method comprises the following steps: After the silicon carbide powder (700) is filled, one of the flow guide blocks (210) is connected to the top of the crucible body (200); The heater (300) is started to make the silicon carbide powder (700) sublimate to form crystal growth gas phase and flow out from the gas phase outlet; The translation mechanism (500) drives the crucible cover (400) to reciprocate along the second direction at a preset speed, so that the seed crystal (410) reciprocates above the gas phase outlet along the second direction, so that the crystal growth gas phase crystallizes on the seed crystal (410).

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