Crucible, 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 crucible, a crystal growth device, a crystal growth method and a method for adjusting solution flow in crystal growth. The crucible is of a non-rotational symmetry structure and comprises a crucible bottom and a crucible wall, the crucible wall is composed of a thick wall part and a thin wall part, the radian of the thin wall part area is 36-180 degrees, the wall thickness of the thin wall part is 10%-90% of the wall thickness of the thick wall part located on the same horizontal plane, and the height of the thin wall part is 30%-100% of the height of the thick wall part. The crucible is designed into an asymmetric structure with non-uniform wall thickness, so that solutions at different positions in the crucible are subjected to different Lorentz forces in a liquid phase growth process, non-axisymmetric unidirectional flowing of the solutions in a seed crystal area is realized, the relative direction of the flowing of the solutions and the step flow of the seed crystal can be adjusted by rotating the crucible or the seed crystal, and the growth speed of the seed crystal is improved. The generation of step coalescence in the crystal growth process is effectively inhibited, and the crystallization quality of the crystal is improved.

Description

Technical Field

[0001] The invention relates to the technical field of crystal growth, and in particular to a crucible, 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 surface of the seed crystal is unidirectional, it is difficult to achieve that the solution flow direction is always opposite to the step flow direction of the seed crystal in the existing crucible design. Summary of the invention

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

[0007] In the first aspect, the present invention provides a crucible, which has a non-rotationally symmetrical structure. The crucible includes a crucible bottom and a crucible wall. The crucible wall consists of a thick-walled portion and a thin-walled portion. The curvature of the thin-walled portion is 36°-180°, that is, the total curvature corresponding to the thin-walled portion accounts for 10%-50% of the total curvature of the crucible, the wall thickness of the thin-walled portion is 10%-90% of the wall thickness of the thick-walled portion located on the same horizontal plane, and the height of the thin-walled portion is 30%-100% of the height of the thick-walled portion.

[0008] Furthermore, the curvature of the thin-walled area is 36°-108°, that is, the total curvature corresponding to the thin-walled area accounts for 10%-30% of the total curvature of the crucible; the wall thickness of the thin-walled part is 40%-80% of the wall thickness of the thick-walled part, and the height of the thin-walled part is 50%-100% of the height of the thick-walled part.

[0009] Furthermore, the curvature of the thin-walled area is 60°, that is, the total curvature corresponding to the thin-walled area accounts for 16.67% of the total curvature of the crucible; the wall thickness of the thin-walled part is 60% of the wall thickness of the thick-walled part, and the height of the thin-walled part is 100% of the height of the thick-walled part.

[0010] Further, the crucible is a graphite crucible; preferably, the density of the graphite crucible is 1.70-2.0 g / cm 3 , and / or, the purity of the graphite crucible is not less than 99.95%.

[0011] In a second aspect, the present invention provides a crystal growth device, comprising the above-mentioned crucible, an insulation layer is provided on the outside of the crucible, and a heating mechanism is provided on the outside of the insulation layer; it also includes a seed crystal shaft, one end of the seed crystal shaft 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 lifting and rotating mechanism is installed on the base. The crucible lifting and rotating mechanism can drive the base to drive the crucible to lift or 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 third aspect, the present invention provides a crystal growth method, specifically, using the above-mentioned crucible or crystal growth device to grow crystals.

[0016] In a fourth aspect, the present invention also provides a method for regulating the flow of solution during crystal growth, using the above-mentioned crucible or 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 crucible as an asymmetric structure with uneven wall thickness, 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 crucible in Example 1.

[0020] Figure 2 It is a schematic diagram of the structure of the crucible in Example 2.

[0021] Figure 3 Schematic diagram of the structure of the crucible in Example 3.

[0022] Figure 4 It is a schematic diagram of the structure of the crucible in Example 4.

[0023] Figure 5 It is a schematic diagram of the structure of the crystal growth device in Example 5.

[0024] Figure 6 This is a simulation diagram of the flow of solution in the crucible during the crystal growth process of Example 5.

[0025] Figure 7 This is a simulation diagram of the flow of solution in a conventional crucible during the crystal growth process of Comparative Example 1.

[0026] Figure 8 This is a simulation diagram of the flow of solution in the crucible during the crystal growth process of Example 6.

[0027] Fig. 9 This is a simulation diagram of the flow of solution in the crucible during the crystal growth process of Example 7.

[0028] Fig.10 This is a simulation diagram of the flow of solution in the crucible during the crystal growth process of Example 8.

[0029] In the figure, 1-thick wall part, 2-thin wall part, 3-crucible, 4-base, 5-crucible lifting and rotating mechanism, 6-insulating layer, 7-heating mechanism, 8-seed crystal axis, 9-seed crystal, 10-seed crystal lifting and rotating mechanism, 11-solution. DETAILED DESCRIPTION

[0030] 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.

[0031] A crucible, the crucible is a non-rotationally symmetrical structure, the crucible comprises a crucible bottom and a crucible wall, the crucible wall consists of a thick wall portion and a thin wall portion; The curvature of the thin-walled area is 36°-180°, preferably 36°-108°, and more preferably 60°; The wall thickness of the thin-walled part is 10%-90% of the wall thickness of the thick-walled part located on the same horizontal plane, preferably 40%-80%, more preferably 60%; The height of the thin-walled portion is 30%-100% of the height of the thick-walled portion, preferably 50%-100%, and more preferably 100%.

[0032] The crucible material is selected from materials acceptable in the field of crystal growth, such as graphite, quartz, corundum, silicon carbide, metal, etc., preferably graphite. More preferably, the density of the graphite crucible is 1.70-2.0 g / cm 3 , and / or, the purity of the graphite crucible is not less than 99.95%.

[0033] A crystal growth device comprises the above-mentioned crucible, wherein an insulation layer is arranged outside the crucible, and a heating mechanism is arranged outside the insulation layer; and further comprises 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 crucible.

[0034] Example 1 like Figure 1 As shown, a crucible has a non-rotationally symmetrical structure. The crucible includes a crucible bottom and a crucible wall. The crucible wall is composed of a continuous thick-walled portion 1 and a continuous thin-walled portion 2. The arc of the thin-walled portion 2 is 60°, and the wall thickness of the thin-walled portion 2 is 60% of the wall thickness of the thick-walled portion 1 located in the same horizontal plane. The height of the thin-walled portion 2 is equal to the height of the thick-walled portion 1.

[0035] Example 2 like Figure 2As shown, a crucible has a non-rotationally symmetrical structure. The crucible includes a crucible bottom and a crucible wall. The crucible wall is composed of a thick-walled portion 1 and a thin-walled portion 2. The curvature of the thin-walled portion 2 is 36°. The thickness of the thin-walled portion 2 is 10% of the thickness of the thick-walled portion 1 located in the same horizontal plane. The thin-walled portion 2 extends downward from the upper edge of the crucible wall, and the height of the thin-walled portion 2 is 75% of the height of the thick-walled portion 1.

[0036] Example 3 like Figure 3 As shown, a crucible is a non-rotationally symmetrical structure. The crucible includes a crucible bottom and a crucible wall. The crucible wall is composed of a thick-walled portion 1 and a thin-walled portion 2. The arc of the thin-walled portion 2 is 180°. The thickness of the thin-walled portion 2 is 90% of the thickness of the thick-walled portion 1 located in the same horizontal plane. The thin-walled portion 2 extends upward from the lower edge of the crucible wall, and the height of the thin-walled portion 2 is 30% of the height of the thick-walled portion 1.

[0037] Example 4 like Figure 4 As shown, a crucible has a non-rotationally symmetrical structure. The crucible comprises a crucible bottom and a crucible wall. The crucible wall consists of three thick-walled portions 1 and three thin-walled portions 2 arranged at intervals. The arcs of the first thick-walled portion, the first thin-walled portion, the second thick-walled portion, the second thin-walled portion, the third thick-walled portion, and the third thin-walled portion are 210°, 30°, 30°, 30°, 30°, 30°, respectively. The thickness of the thin-walled portion 2 is 20% of the thickness of the thick-walled portion 1 located in the same horizontal plane, and the height of the thin-walled portion 2 is equal to that of the thick-walled portion 1.

[0038] Example 5 Taking silicon carbide crystal as an example, a crystal growth device is used for growth. The structure of the crystal growth device is as follows: The crucible 3 of embodiment 1 is made of graphite and has a density of 1.70-2.0 g / cm 3 The purity of the crucible 3 is not less than 99.95%, and the crucible is filled with growth raw materials, which include silicon and metal elements (including chromium, titanium, and aluminum); The crucible 3 is placed on the base 4. To realize the lifting and / or rotation of the crucible in the crystal growth device, a crucible lifting and rotating mechanism 5 can be installed on the base 4 according to the prior art. The crucible lifting and rotating mechanism 5 can drive the base 4 to drive the crucible 3 to lift or rotate to a preset position. A heat preservation layer 6 is disposed outside the crucible 3, and a heating mechanism 7 is disposed outside the heat preservation layer 6. The heating mechanism 7 may be an induction coil or the like; It also includes a seed crystal shaft 8, one end of which is fixed with a seed crystal 9 and extends into the crucible 3. In order to realize the lifting and / or rotation of the seed crystal in the crystal growth device, a seed crystal lifting and rotating mechanism 10 can be installed at the other end of the seed crystal shaft 8 according to the existing technology. The seed crystal lifting and rotating mechanism 10 can drive the seed crystal shaft 8 to drive the seed crystal 9 to lift or rotate to a preset position.

[0039] A protective gas is introduced into the crystal growth device, and the crucible is heated by a heating mechanism to raise the temperature of the crucible to above the melting point of the growth raw material. The molten growth raw material corrodes the inner wall of the crucible to form a silicon liquid containing carbon in the crucible. The crucible lifting and rotating mechanism and / or the seed crystal lifting and rotating mechanism are adjusted to make the seed crystal contact with the solution.

[0040] COMSOL software was used to simulate and verify the flow direction of the solution inside the crucible when using an off-axis seed crystal in the crystal growth device of this embodiment. The purpose of using an off-axis seed crystal is to maintain the stability of the crystal form. The results are as follows Figure 6 As shown, due to the inconsistent thickness of the crucible wall, 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 region. 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.

[0041] Comparative Example 1 The crucible material and the composition and connection relationship of the crystal growth device in this comparative example are the same as those in Example 5, the only difference being that a conventional crucible with a consistent crucible wall thickness is used instead of the crucible in Example 1.

[0042] COMSOL software was used to simulate and verify the flow direction of the solution inside the crucible when using an off-axis seed crystal in the crystal growth device of this comparative example. The purpose of using an off-axis seed crystal is to maintain the stability of the crystal form. The results are as follows Figure 7 As shown, since the crucible used in Comparative Example 1 is of rotationally symmetrical design and has uniform wall thickness, the solution flow at this time 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 the general area is opposite, and the other half of the area is the same.

[0043] Example 6 The crucible material and the composition and connection relationship of the crystal growth device in this embodiment are the same as those in Embodiment 5, the only difference being that the crucible of Embodiment 2 is used instead of the crucible of Embodiment 1.

[0044] COMSOL software was used to simulate and verify the flow direction of the solution inside the crucible when using an off-axis seed crystal in the crystal growth device of this embodiment. The purpose of using an off-axis seed crystal is to maintain the stability of the crystal form. The results are as follows Figure 8As shown, at this time, 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.

[0045] Example 7 The crucible material and the composition and connection relationship of the crystal growth device in this embodiment are the same as those in Embodiment 5, the only difference being that the crucible of Embodiment 3 is used instead of the crucible of Embodiment 1.

[0046] COMSOL software was used to simulate and verify the flow direction of the solution inside the crucible when using an off-axis seed crystal in the crystal growth device of this embodiment. The purpose of using an off-axis seed crystal is to maintain the stability of the crystal form. The results are as follows Fig. 9 As shown, at this time, 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.

[0047] Example 8 The crucible material and the composition and connection relationship of the crystal growth device in this embodiment are the same as those in Embodiment 5, the only difference being that the crucible of Embodiment 4 is used instead of the crucible of Embodiment 1.

[0048] COMSOL software was used to simulate and verify the flow direction of the solution inside the crucible when using an off-axis seed crystal in the crystal growth device of this embodiment. The purpose of using an off-axis seed crystal is to maintain the stability of the crystal form. The results are as follows Fig.10 As shown, the flow direction of the solution is non-axisymmetric at this time, and the step flow direction of the seed crystal is adjusted to be opposite to the flow direction of the solution by controlling the rotation of the crucible and / or the seed crystal. The effect of opening multiple grooves on the side wall is the sum of the effects of each groove.

[0049] 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 crucible, characterized in that: The crucible has a non-rotationally symmetrical structure, comprising a crucible bottom and a crucible wall. The crucible wall consists of a thick-walled portion and a thin-walled portion. The curvature of the thin-walled portion is 36°-180°, the thickness of the thin-walled portion is 10%-90% of the thickness of the thick-walled portion located in the same horizontal plane, and the height of the thin-walled portion is 30%-100% of the height of the thick-walled portion.

2. The crucible according to claim 1, characterized in that The curvature of the thin-walled area is 36°-108°, the wall thickness of the thin-walled area is 40%-80% of the wall thickness of the thick-walled area, and the height of the thin-walled area is 50%-100% of the height of the thick-walled area.

3. The crucible according to claim 1, characterized in that The arc of the thin-walled area is 60°, the wall thickness of the thin-walled area is 60% of the wall thickness of the thick-walled area, and the height of the thin-walled area is 100% of the height of the thick-walled area.

4. The crucible according to claim 1, characterized in that The crucible is a graphite crucible.

5. The crucible according to claim 4, characterized in that The density of graphite crucible is 1.70-2.0g / cm 3 , and / or, the purity of the graphite crucible is not less than 99.95%.

6. A crystal growth device, characterized in that: It comprises the crucible as described in any one of claims 1-5, the outer side of the crucible is provided with an insulation layer, and the outer side of the insulation layer is provided with a heating mechanism; it also comprises a seed crystal shaft, one end of the seed crystal shaft is used to fix the seed crystal, and the end of the seed crystal shaft used to fix the seed crystal extends into the crucible.

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

8. The crystal growth apparatus according to claim 6, 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.

9. A crystal growth method, characterized in that: Crystal growth is carried out using the crucible as described in any one of claims 1 to 5 or the crystal growth device as described in any one of claims 6 to 8.

10. A method for regulating the flow of a solution during crystal growth, characterized in that: Crystal growth is performed using the crucible as described in any one of claims 1 to 5 or the crystal growth device as described in any one of claims 6 to 8, 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 seed crystal step flow direction.

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