Crucible, application thereof and crystal growth method

Abstract

The invention relates to the technical field of crystal growth, in particular to a crucible, application of the crucible and a crystal growth method. The crucible comprises a crucible body, a slope block is arranged at the bottom in the crucible body, the slope block is a cylinder with the upper surface being a slope, and a gap allowing a solution formed by melting growth raw materials to enter does not exist between the slope block and the crucible body. The vertical distance from the highest position of the upper surface of the slope block to the lowest position of the upper surface of the slope block is 45%-80% of the height of the liquid level of a solution contained in the crucible body. The slope block is arranged at the bottom in the crucible body, so that the crucible is of a non-rotational symmetric structure, a solution flows in a single direction in a seed crystal area, and the flowing direction of the solution is simply and efficiently controlled to be kept constant. By rotating the seed crystal or the crucible, the relative direction of the flowing of the solution and the step flow of the seed crystal can be adjusted, the generation of step coalescence in the growth process of the crystal 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 and an application thereof and a crystal growth method. 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] The inner bottom of the existing crucible is designed as a horizontal bottom with uniform wall thickness and an axisymmetric structure. 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 flow direction of the solution 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 flow direction of the solution is always opposite to the step flow direction of the seed crystal in the existing crucible design, the present invention provides a crucible and its application and a crystal growth method.

[0007] In a first aspect, the present invention provides a crucible, comprising a crucible body, wherein a slope block is arranged at the inner bottom of the crucible body, the slope block being a cylinder with an inclined upper surface, and no gap between the slope block and the crucible body allowing a solution formed by melting a growth raw material to enter, and a vertical distance from the highest point on the upper surface of the slope block to the lowest point on the upper surface of the slope block is 45%-80% of the liquid level of the solution contained in the crucible body.

[0008] Furthermore, the slope block and the crucible body are integrally formed.

[0009] Furthermore, the slope block and the crucible body are split structures.

[0010] Furthermore, the slope block is made of the same material as the crucible body.

[0011] Furthermore, the slope block and the crucible body are both made of graphite; preferably, the density of the slope block and the crucible body is 1.70-2.0 g / cm 3 , and / or, the purity of graphite is not less than 99.95%.

[0012] In a second aspect, the present invention provides a use of the above-mentioned crucible in crystal growth.

[0013] In a third aspect, the present invention also provides a crystal growth method, using a crucible having a slope block at the bottom of a crucible body, the slope block being a cylinder with an inclined upper surface, and no gap between the slope block and the crucible body allowing a solution formed by the melted growth raw material to enter, the growth raw material is heated to grow crystals, and the amount of growth raw material added is controlled such that the vertical distance from the highest point on the upper surface of the slope block to the lowest point on the upper surface of the slope block is 45%-80% of the liquid level of the solution formed by the melted growth raw material in the crucible body.

[0014] Furthermore, when the crystal grows, the seed crystal or the crucible is rotated to adjust the flow direction of the solution 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.

[0015] The beneficial effects of the present invention are: The present invention arranges a slope block at the bottom of the crucible body, so that the crucible presents a non-rotationally symmetrical structure, realizes the unidirectional flow of the solution in the seed crystal area, and simply and efficiently controls the solution flow direction 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, effectively suppressing the generation of step aggregation during crystal growth, and 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

[0016] 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.

[0017] Figure 1 is a cross-sectional view of the graphite crucible in Example 1.

[0018] Figure 2This is a side view of the flow state of the solution in the graphite crucible simulated using COMSOL simulation software in Example 1.

[0019] Figure 3 This is a top view of the flow state of the solution in the graphite crucible simulated using COMSOL simulation software in Example 1.

[0020] Figure 4 It is a cross-sectional view of the graphite crucible in Example 2.

[0021] Figure 5 This is a side view of the flow state of the solution in the graphite crucible simulated using COMSOL simulation software in Example 2.

[0022] Figure 6 This is a top view of the flow state of the solution in the graphite crucible simulated using COMSOL simulation software in Example 2.

[0023] Figure 7 This is a cross-sectional view of the graphite crucible in Comparative Example 1.

[0024] Figure 8 This is a side view of the flow state of the solution in the graphite crucible simulated using COMSOL simulation software in Comparative Example 1.

[0025] Fig. 9 This is a top view of the flow state of the solution in the graphite crucible simulated using COMSOL simulation software in Comparative Example 1.

[0026] In the figure, 1-crucible body, 2-slope block, 3-solution, 4-seed crystal. DETAILED DESCRIPTION

[0027] 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.

[0028] Example 1 like Figure 1As shown, a graphite crucible includes a crucible body 1, the crucible body 1 is a cup-shaped structure with uniform thickness and height at all parts of the side wall, and the bottom thickness of the crucible body 1 is also uniform, a slope block 2 is arranged at the bottom of the crucible body 1, the slope block 2 is a cylinder with an inclined upper surface, the size of the cylinder is adapted to the inner diameter of the crucible body 1, the slope block 2 and the crucible body 1 are integrally formed, and the vertical distance from the highest point on the upper surface of the slope block 2 to the lowest point on the upper surface of the slope block 2 is h1. The adaptation and integral forming mentioned here means that the outer side surface of the slope block 2 and the inner side surface of the crucible body 1 are connected to each other without gaps, and are an integral whole, ensuring that there is no gap between the slope block 2 and the crucible body 1 to allow the solution 3 formed by the melting of the growth raw materials to enter.

[0029] The graphite crucible of this embodiment is used for crystal growth, and a certain amount of growth raw material is added to the crucible. The amount of growth raw material added m1 is determined according to the slope height (h1). Taking the preparation of silicon carbide crystal as an example, the growth raw materials are silicon and metal elements, such as chromium, titanium, aluminum, etc. The crucible is placed inside the crystal growth device, and the crucible is heated by a heating mechanism. When the crucible temperature rises above the melting point of the growth raw material, a solution with silicon as solvent and carbon as solute is formed in the crucible. At this time, the liquid level of the solution is h2, and h1=45%×h2 is satisfied. Then, the position of the seed crystal is adjusted to make it contact with the solution, and crystal growth is carried out. Due to the slope block structure at the bottom of the crucible body, the solution flows in a single direction in the seed crystal area. By controlling the rotation of the crucible and / or the seed crystal to adjust the flow direction of the solution, the flow direction of the solution can always be opposite to the step flow direction of the seed crystal.

[0030] COMSOL simulation software was used for verification. Figure 2 This is a lateral cross-sectional view of the graphite crucible of this embodiment along the direction perpendicular to the solution flow. The upper rectangular block represents the seed crystal 4, and the lower rectangular block represents the interior of the crucible. The arrow area represents the solution 3, the arrow is the solution flow direction, and the arrow length represents the solution flow rate. The area without an arrow represents the slope block 2. It can be seen that the flow in the solution at the lower part of the seed crystal area is also in a single direction. Figure 3 This is a top view of the graphite crucible of this embodiment, wherein the outer circle represents the inner diameter of the crucible, the inner circle represents the seed crystal, the arrow is the flow direction of the solution, and the length of the arrow represents the flow rate of the solution. It can be seen that a single solution flows in the seed crystal area.

[0031] Example 2 like Figure 4As shown, a graphite crucible includes a crucible body 1, the crucible body 1 is a cup-shaped structure with uniform thickness and height at all parts of the side wall, and the bottom thickness of the crucible body 1 is also uniform, a slope block 2 is arranged at the bottom of the crucible body 1, the slope block 2 is a cylinder with an inclined upper surface, and the size of the cylinder is adapted to the inner diameter of the crucible body 1, the slope block 2 and the crucible body 1 are split structures, and the vertical distance from the highest point of the upper surface of the slope block 2 to the lowest point of the upper surface of the slope block 2 is h1'. The adaptation mentioned here means that after the slope block 2 is placed inside the crucible body 1, the outer side surface of the slope block 2 and the inner side surface of the crucible body 1 are tightly fitted and sealed to ensure that there is no gap between the slope block 2 and the crucible body 1 that allows the solution 3 formed by the melting of the growth raw material to enter. The assembly method of the slope block 2 and the crucible body 1 can be fixedly connected by bonding, sleeve connection, etc. according to the material.

[0032] The graphite crucible of this embodiment is used for crystal growth, and a certain amount of growth raw material is added to the crucible. The amount of growth raw material added m1' is determined according to the height of the slope (h1'). Taking the preparation of silicon carbide crystal as an example, the growth raw materials are silicon and metal elements, such as chromium, titanium, aluminum, etc. The crucible is placed inside the crystal growth device, and the crucible is heated by a heating mechanism. When the crucible temperature rises above the melting point of the growth raw material, a solution with silicon as solvent and carbon as solute is formed in the crucible. At this time, the liquid level of the solution is h2', and h1'=80%×h2' is satisfied. Then, the position of the seed crystal is adjusted to make it contact with the solution, and crystal growth is carried out. Due to the slope block structure at the bottom of the crucible body, the solution flows in a single direction in the seed crystal area. By controlling the rotation of the crucible and / or the seed crystal to adjust the flow direction of the solution, the flow direction of the solution can always be opposite to the step flow direction of the seed crystal.

[0033] COMSOL simulation software was used for verification. Figure 5 This is a lateral cross-sectional view of the graphite crucible of this embodiment along the direction perpendicular to the solution flow. The upper rectangular block represents the seed crystal 4, and the lower rectangular block represents the interior of the crucible. The arrow area represents the solution 3, the arrow is the solution flow direction, and the arrow length represents the solution flow rate. The area without an arrow represents the slope block 2. It can be seen that the flow in the solution at the lower part of the seed crystal area is also in a single direction. Figure 6 This is a top view of the graphite crucible of this embodiment, wherein the outer circle represents the inner diameter of the crucible, the inner circle represents the seed crystal, the arrow is the flow direction of the solution, and the length of the arrow represents the flow rate of the solution. It can be seen that a single solution flows in the seed crystal area.

[0034] Comparative Example 1 like Figure 7 As shown, a graphite crucible comprises a crucible body 1. The crucible body 1 is a cup-shaped structure with uniform thickness and height at all sides of the side wall, and the bottom thickness of the crucible body 1 is also uniform.

[0035] A growth raw material with a mass of m1 (the same as in Example 1) is added to the graphite crucible of this comparative example, and the heating mechanism is turned on to heat the graphite crucible. After the solution is formed, the position of the seed crystal is adjusted so that it contacts the solution to grow the crystal. Since the inner bottom of the graphite crucible is a plane, the flow direction of the solution in the crucible of this comparative example is symmetrical from the center to the surroundings.

[0036] COMSOL simulation software was used for verification. Figure 8 This is a lateral cross-sectional view of the graphite crucible of this comparative example along the direction perpendicular to the solution flow. The upper rectangular block represents the seed crystal 4, and the lower rectangular block represents the inside of the crucible. The arrow area represents the solution 3, the arrow is the solution flow direction, and the arrow length represents the solution flow rate. It can be seen that the flow inside the solution is axisymmetric. Fig. 9 This is a top view of the graphite crucible of this comparative example, wherein the outer circle represents the inner diameter of the crucible, the inner circle represents the seed crystal, the arrow is the flow direction of the solution, and the length of the arrow represents the flow rate of the solution. It can be seen that the seed crystal area is uniformly axially symmetrical.

[0037] 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, comprising a crucible body, characterized in that: A slope block is arranged at the bottom of the crucible body. The slope block is a column with an inclined upper surface. There is no gap between the slope block and the crucible body to allow the solution formed by the melting of the growth raw materials to enter. The vertical distance from the highest point on the upper surface of the slope block to the lowest point on the upper surface of the slope block is 45%-80% of the liquid level of the solution contained in the crucible body.

2. The crucible according to claim 1, characterized in that The slope block and the crucible body are integrally formed or split structures.

3. The crucible according to claim 1, characterized in that The slope block is made of the same material as the crucible body.

4. The crucible according to claim 3, characterized in that The slope block and the crucible body are both made of graphite.

5. Use of the crucible according to any one of claims 1 to 4 in crystal growth.

6. A crystal growth method, characterized in that: A crucible with a slope block at the bottom of the crucible body is used. The slope block is a column with an inclined upper surface. There is no gap between the slope block and the crucible body to allow the solution formed by the melted growth raw material to enter. The growth raw material is heated to grow crystals. The vertical distance from the highest point on the upper surface of the slope block to the lowest point on the upper surface of the slope block is 45%-80% of the liquid level of the solution formed by the melted growth raw material in the crucible body to control the amount of growth raw material added.

7. The crystal growth method according to claim 6, characterized in that When the crystal grows, the seed crystal is rotated to adjust the flow direction of the solution 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.

8. The crystal growth method according to claim 6, characterized in that When the crystal grows, the crucible is rotated to adjust the flow direction of the solution 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.

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