Crystal growth device, crystal growth method and method for adjusting solution flow in crystal growth

Abstract

The invention relates to the technical field of crystal growth, in particular to a crystal growth device, a crystal growth method and a method for adjusting solution flow in crystal growth. The crystal growth device comprises a crucible, a hot wall is arranged on the outer side of the crucible, and a heat preservation layer and a heating mechanism are arranged on the outer side of the hot wall. The hot wall is of a non-rotational-symmetry cylindrical structure with the outer side face being slotted, and the radian of the slotted area of the outer side face of the hot wall ranges from 36 degrees to 180 degrees. The thickness of the slotted area is less than or equal to 90% of the thickness of the non-slotted hot wall on the same horizontal plane; the height of the slotting area is 30%-100% of the height of the hot wall. The hot wall of the crystal growth device is designed to be of a non-rotational symmetric cylindrical structure, so that solutions at different positions in the crucible are subjected to different Lorentz forces in the liquid phase growth process, non-axisymmetric unidirectional flow of the solutions in a seed crystal area is realized, and the crystal growth speed is increased by rotating the crucible or seed crystals. The relative direction of solution flow and seed crystal step flow can be adjusted, and generation of step coalescence in the crystal growth process is effectively inhibited.

Description

Technical Field

[0001] The invention relates to the technical field of crystal growth, and in particular to a crystal growth device, a crystal growth method and a method for regulating solution flow during crystal growth. Background Art

[0002] Crystal quality is one of the decisive factors affecting the performance of semiconductor devices, so crystal growth control is a key process in semiconductor device manufacturing.

[0003] At present, the commonly used crystal growth techniques include liquid phase growth, vapor phase growth, molecular beam epitaxy and hydrothermal method. Among them, the liquid phase growth method is widely used because of its fast crystal growth rate, low crystal growth temperature requirement, growth process close to thermodynamic equilibrium, and can eliminate threading dislocations in the substrate. Common semiconductor materials such as silicon, germanium, silicon carbide, etc. can be prepared by liquid phase growth method.

[0004] The growth device of the liquid phase growth method includes a crucible and a seed crystal shaft. A seed crystal is fixed at one end of the seed crystal shaft. The seed crystal extends into the crucible. The rotation of the seed crystal shaft drives the solution in the crucible to flow. Studies have shown that the flow of the solution has an extremely important influence on the quality of the crystal. When the solution flow direction is the same as the step flow direction of the seed crystal, the crystal tends to form large steps; when the solution flow direction is opposite to the step flow direction of the seed crystal, the crystal surface tends to form small steps. If the step on the crystal surface is too high, solution inclusions are likely to appear at the edge of the step, reducing the quality of the crystal. Therefore, controlling the solution flow direction to always be opposite to the step flow direction of the seed crystal during crystal growth is more conducive to obtaining high-quality crystals.

[0005] At present, the common crucibles are all designed in a rotationally symmetrical cup shape. The solution formed by the rotation of the seed crystal axis will flow symmetrically around the seed crystal axis. Since the flow direction of the steps on the seed crystal surface is unidirectional, it is difficult to use conventional crucibles to achieve that the solution flow direction is always opposite to the step flow direction of the seed crystal. Summary of the invention

[0006] In view of the technical problem that it is difficult to use a conventional crucible to ensure that the solution flow direction is always opposite to the step flow direction of the seed crystal, the present invention provides a crystal growth device, a crystal growth method and a method for regulating the solution flow during crystal growth.

[0007] In a first aspect, the present invention provides a crystal growth device, including a crucible, a hot wall is provided on the outside of the crucible, a heat preservation layer is provided on the outside of the hot wall, and a heating mechanism is provided on the outside of the heat preservation layer; The heat wall is a non-rotationally symmetrical cylindrical structure with grooves on the outer side, and the arc of the groove area on the outer side of the heat wall is 36°-180°, such as 45°, 60°, 72°, 75°, 90°, 105°, 108°, 120°, 135°, 144°, 150°, 165°, 180°, etc., wherein the arc of the groove area refers to the sum of the arcs continuously spanned by the groove body on the outer side of the heat wall in the circumferential direction; The thickness of the slotted area is ≤ 90% of the thickness of the unslotted hot wall on the same horizontal plane. For example, the thickness of the slotted area is 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, etc. of the thickness of the unslotted hot wall on the same horizontal plane. When the thickness of the slotted area is 0% of the thickness of the unslotted hot wall on the same horizontal plane, it means that the slot body is a through slot along the direction of the hot wall thickness. The height of the slotted area is 30%-100% of the height of the hot wall, wherein the height of the slotted area refers to the vertical distance from the horizontal plane where the highest point of the slot body on the outer side of the hot wall is located to the horizontal plane where the lowest point is located.

[0008] Furthermore, the arc of the slotted area is 36°-108°, the thickness of the slotted area is 40%-80% of the thickness of the unslotted hot wall on the same horizontal plane, and the height of the slotted area is 50%-100% of the height of the hot wall.

[0009] Furthermore, the arc of the slotted area is 60°, the thickness of the slotted area is 60% of the thickness of the unslotted hot wall on the same horizontal plane, and the height of the slotted area is 100% of the height of the hot wall.

[0010] Furthermore, the material of the hot wall is selected from materials acceptable in the field of crystal growth, such as graphite, quartz, corundum, silicon carbide, metal, etc., preferably graphite.

[0011] Furthermore, it also includes a seed crystal shaft, one end of which is used to fix the seed crystal, and the end of the seed crystal shaft used to fix the seed crystal extends into the interior of the crucible.

[0012] Furthermore, the heating mechanism is an induction coil.

[0013] Furthermore, the crucible is placed on a base, and a crucible rotating mechanism is installed on the base. The crucible rotating mechanism can drive the base to drive the crucible to rotate.

[0014] Furthermore, a seed crystal lifting and rotating mechanism is installed at the other end of the seed crystal shaft, and the seed crystal lifting and rotating mechanism can drive the seed crystal shaft to drive the seed crystal to lift or rotate.

[0015] In a second aspect, the present invention provides a crystal growth method, specifically, using the above-mentioned crystal growth device to grow crystals.

[0016] In a third aspect, the present invention also provides a method for regulating the flow of solution during crystal growth, using the above-mentioned crystal growth device to grow crystals, and adjusting the flow direction of the solution by rotating the seed crystal or the crucible so that the flow direction of the solution on the surface of the seed crystal is opposite to the step flow direction of the seed crystal.

[0017] The beneficial effects of the present invention are: The present invention designs the hot wall of the crystal growth device as a non-rotationally symmetric cylindrical structure, so that the solutions at different positions in the crucible are subjected to different Lorentz forces during the liquid phase growth process, and the non-axisymmetric unidirectional flow of the solution in the seed crystal region is realized, and the flow direction of the solution is simply and efficiently controlled to remain constant. By rotating the crucible or the seed crystal, the relative direction of the solution flow and the seed crystal step flow can be adjusted, and the generation of step aggregation during the crystal growth process can be effectively suppressed, thereby improving the crystallization quality of the crystal. At the same time, under the premise of ensuring the quality of the crystal, a longer growth time can be achieved, so that a thicker ingot can be obtained in one growth, and the output is effectively improved without increasing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 It is a schematic diagram of the structure of the crystal growth device in Example 1.

[0020] Figure 2 It is a schematic diagram of the three-dimensional structure of the heat wall in Example 1.

[0021] Figure 3 It is a schematic diagram of the assembly of the hot wall and the crucible in Example 1.

[0022] Figure 4 This is a simulation diagram of the flow of solution in the crucible when crystal growth is performed using the crystal growth apparatus of Example 1.

[0023] Figure 5 It is a schematic diagram of the three-dimensional structure of the heat wall in Example 2.

[0024] Figure 6 It is a schematic diagram of the assembly of the hot wall and the crucible in Example 2.

[0025] Figure 7 This is a simulation diagram of the flow of solution in the crucible when crystal growth is performed using the crystal growth apparatus of Example 2.

[0026] Figure 8 It is a schematic diagram of the three-dimensional structure of the heat wall in Example 3.

[0027] Fig. 9 It is a schematic diagram of the assembly of the hot wall and the crucible in Example 3.

[0028] Fig.10 This is a simulation diagram of the flow of solution in the crucible when crystal growth is performed using the crystal growth apparatus of Example 3.

[0029] Fig.11 It is a schematic diagram of the three-dimensional structure of the heat wall in Example 4.

[0030] Fig.12 It is a schematic diagram of the assembly of the hot wall and the crucible in Example 4.

[0031] Fig.13 This is a simulation diagram of the flow of solution in the crucible when crystal growth is performed using the crystal growth apparatus of Example 4.

[0032] Fig.14 This is a simulation diagram of the flow of solution in a conventional crucible during the crystal growth process of Comparative Example 1.

[0033] In the figure, 1-seed crystal lifting and rotating mechanism, 2-crucible, 3-hot wall, 4-insulating layer, 5-heating mechanism, 6-solution, 7-crucible rotating mechanism, 8-base, 9-seed crystal, 10-seed crystal axis. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0035] Example 1 like Figures 1 to 3 As shown, a crystal growth device includes a crucible 2, which can use a conventional cup-shaped crucible. The crucible 2 is placed on a base 8, on which a crucible rotating mechanism 7 is installed, and the crucible rotating mechanism 7 can drive the base 8 to drive the crucible 2 to rotate; it also includes a seed crystal shaft 10, one end of the seed crystal shaft 10 is used to fix a seed crystal 9, and one end of the seed crystal shaft 10 for fixing the seed crystal 9 extends into the crucible 2, and the other end of the seed crystal shaft 10 is installed with a seed crystal lifting and rotating mechanism 1, and the seed crystal lifting and rotating mechanism 1 can drive the seed crystal shaft 10 to drive the seed crystal 9 to lift or rotate; a hot wall 3 is provided on the outside of the crucible 2, the hot wall 3 is made of graphite, an insulation layer 4 is provided on the outside of the hot wall 3, and a heating mechanism 5 (such as an induction coil, etc.) is provided on the outside of the insulation layer 4; The heat wall 3 is a non-rotationally symmetrical cylindrical structure with grooves on the outer side. The arc of the groove area on the outer side of the heat wall 3 is 60°, where the arc of the groove area refers to the sum of the arcs continuously spanned by the groove body on the outer side of the heat wall 3 in the circumferential direction; The thickness of the slotted area is 60% of the thickness of the unslotted hot wall on the same horizontal plane; The height of the slotted area is 100% of the height of the hot wall 3 , wherein the height of the slotted area refers to the vertical distance from the horizontal plane where the highest point of the slot body on the outer side of the hot wall 3 is located to the horizontal plane where the lowest point is located.

[0036] When in use, protective gas is introduced into the crystal growth device, and the crucible 2 is heated by the heating mechanism 5 to raise the temperature of the crucible 2 to above the melting point of the growth raw material, and the molten growth raw material corrodes the inner wall of the crucible 2 to form silicon liquid containing carbon in the crucible 2. The crucible rotating mechanism 7 and / or the seed crystal lifting and rotating mechanism 1 are adjusted to make the seed crystal 9 contact with the solution 6.

[0037] COMSOL software was used to simulate and verify the flow direction of the solution inside the crucible when SiC was grown in the crystal growth device of this embodiment using an off-axis seed crystal. The purpose of using an off-axis seed crystal is to maintain the stability of the crystal form. The results are as follows Figure 4 As shown, due to the inconsistent thickness of the hot wall surrounding the outside of the crucible, the solution at different positions inside the crucible is subjected to different Lorentz forces, and the solution flows in an asymmetric unidirectional manner in the seed crystal area. By controlling the rotation of the crucible and / or the seed crystal, the step flow direction of the seed crystal is adjusted to be opposite to the flow direction of the solution.

[0038] Example 2 On the basis of Example 1, Figures 5 and 6 As shown, the difference of the crystal growth device of Example 2 is: The arc of the slotted area on the outer side of the hot wall is 36°, where the arc of the slotted area refers to the sum of the arcs continuously spanned by the slot body on the outer side of the hot wall in the circumferential direction; The thickness of the slotted area is 0% of the thickness of the unslotted hot wall on the same horizontal plane; The height of the slotted area is 75% of the height of the hot wall, where the height of the slotted area refers to the vertical distance from the horizontal plane where the highest point of the slot body on the outer side of the hot wall is located to the horizontal plane where the lowest point is located.

[0039] like Figure 7 As shown, it has been verified by COMSOL software simulation that when the crystal growth device of this embodiment is used to grow off-axis seed crystals, the flow direction of the solution is non-axisymmetric. By controlling the rotation of the crucible and / or the seed crystal, the step flow direction of the seed crystal is adjusted to be opposite to the flow direction of the solution.

[0040] Example 3 On the basis of Example 1, Figures 8 to 9As shown, the difference of the crystal growth device of Example 3 is: The arc of the slotted area on the outer side of the hot wall is 180°, where the arc of the slotted area refers to the sum of the arcs continuously spanned by the slot body on the outer side of the hot wall in the circumferential direction; The thickness of the slotted area is 0% of the thickness of the unslotted hot wall on the same horizontal plane; The height of the slotted area is 30% of the height of the hot wall, where the height of the slotted area refers to the vertical distance from the horizontal plane where the highest point of the slot body on the outer side of the hot wall is located to the horizontal plane where the lowest point is located.

[0041] like Fig.10 As shown, COMSOL software simulation verifies that when the crystal growth device of this embodiment is used to grow off-axis seed crystals, the flow direction of the solution is non-axisymmetric. By controlling the rotation of the crucible and / or the seed crystal, the step flow direction of the seed crystal is adjusted to be opposite to the solution flow direction.

[0042] Example 4 On the basis of Example 1, Figure 11 to Figure 12 As shown, the difference of the crystal growth device of Example 4 is: The slotted area on the outer side of the hot wall consists of slot A, slot B and slot C, wherein the arcs of slot A, slot B and slot C are all 30°, the arc of the hot wall between slot A and slot B is 30°, the arc of the hot wall between slot B and slot C is 30°, and the arc of the hot wall between slot C and slot A is 210°; The thickness of the slotted area is 20% of the thickness of the unslotted hot wall on the same horizontal plane; The slotted area height is equal to the hot wall height.

[0043] like Fig.13 As shown, COMSOL software simulation verifies that when the crystal growth device of this embodiment is used to grow off-axis seed crystals, the flow direction of the solution is non-axisymmetric. By controlling the rotation of the crucible and / or the seed crystal, the step flow direction of the seed crystal is adjusted to be opposite to the flow direction of the solution. The effect of opening multiple grooves on the side wall is the sum of the effects of each groove.

[0044] Comparative Example 1 The composition and connection relationship of the crystal growth device in this comparative example are basically the same as those in Example 1, except that the crystal growth device in Comparative Example 1 is not provided with a hot wall.

[0045] like Fig.14 As shown, COMSOL software simulation verifies that when the comparative crystal growth device is used to grow off-axis seed crystals, the solution flow is an axisymmetric flow with the center of the seed crystal as the axis. Since the step flow is unidirectional, it cannot be guaranteed that the step flow is opposite to the solution flow direction. Only half of the area is opposite, and the other half is the same.

[0046] Although the present invention has been described in detail with reference to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A crystal growth device, comprising a crucible, characterized in that: A hot wall is arranged outside the crucible, a heat preservation layer is arranged outside the hot wall, and a heating mechanism is arranged outside the heat preservation layer; The hot wall is a non-rotationally symmetrical cylindrical structure with grooves on the outer side. The arc of the groove area on the outer side of the hot wall is 36°-180°; the thickness of the groove area is ≤ 90% of the thickness of the ungrooved hot wall on the same horizontal plane; the height of the groove area is 30%-100% of the height of the hot wall.

2. The crystal growth apparatus according to claim 1, wherein: The arc of the slotted area is 36°-108°, the thickness of the slotted area is 40%-80% of the thickness of the unslotted hot wall on the same horizontal plane, and the height of the slotted area is 50%-100% of the height of the hot wall.

3. The crystal growth apparatus according to claim 1, wherein: The arc of the slotted area is 60°, the thickness of the slotted area is 60% of the thickness of the unslotted hot wall on the same horizontal plane, and the height of the slotted area is 100% of the hot wall height.

4. The crystal growth apparatus according to claim 1, wherein: It also includes a seed crystal shaft, one end of which is used to fix the seed crystal, and the other end of the seed crystal shaft used to fix the seed crystal extends into the crucible.

5. The crystal growth apparatus according to claim 1, wherein: The heating mechanism is an induction coil.

6. The crystal growth apparatus according to claim 1, wherein: The crucible is placed on a base, and a crucible rotating mechanism is installed on the base. The crucible rotating mechanism can drive the base to drive the crucible to rotate.

7. The crystal growth apparatus according to claim 1, wherein: The other end of the seed crystal shaft is equipped with a seed crystal lifting and rotating mechanism, which can drive the seed crystal shaft to drive the seed crystal to lift or rotate.

8. A crystal growth method, characterized in that: Crystal growth is carried out using the crystal growth apparatus as described in any one of claims 1 to 7.

9. A method for regulating the flow of a solution during crystal growth, characterized in that: The crystal growth device as described in any one of claims 1 to 7 is used to grow crystals, and the solution flow direction is adjusted by rotating the seed crystal or the crucible so that the solution flow direction on the seed crystal surface is opposite to the step flow direction of the seed crystal.

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