Liquid phase method crystal growth device and method
By setting up a gas interlayer in the liquid phase crystal growth device, the heat dissipation enhancement problem caused by polycrystalline silicon carbide at the bottom of the crucible is solved, the internal temperature of the solution is achieved, and the growth quality of the crystal is improved.
Patent Information
- Application Number
- CN202411278781.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-12
- Publication Date
- 2025-01-14
AI Technical Summary
In the existing liquid phase crystal growth technology, the formation of polycrystalline silicon carbide at the bottom of the crucible leads to enhanced heat dissipation, affecting the stability of the internal temperature distribution of the solution, and thus affecting the stability of crystal growth.
A partition is provided at the bottom of the crucible, and a gas interlayer is formed with the bottom of the crucible through a lifting mechanism to offset the heat dissipation enhancement phenomenon caused by the high thermal conductivity of polycrystalline silicon carbide and maintain the stability of the internal temperature field of the solution.
Compensation with the gas interlayer reduces heat dissipation at the bottom of the crucible, ensures the stability of the internal temperature of the solution, and improves the growth quality of the crystal.
Smart Images
Figure CN119308005A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of crystal growth, and in particular to a liquid phase crystal growth device and 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] Taking the liquid phase growth of silicon carbide as an example, the growth device used includes a crucible, an induction coil is arranged around the side wall of the crucible, and the seed crystal axis extends into the crucible from the top. This method often forms a layer of polycrystalline silicon carbide (such as Figure 1 ). Since the thermal conductivity of polycrystalline silicon carbide is higher than that of the solution, the formation of polycrystalline silicon carbide at the bottom of the crucible will lead to enhanced heat dissipation at the bottom of the crucible, thereby changing the temperature distribution inside the entire solution and affecting the stability of long-term growth. Summary of the invention
[0005] In order to solve the technical problem that the formation of polycrystals at the bottom of the crucible affects the temperature distribution inside the solution and causes unstable crystal growth, the present invention provides a liquid phase crystal growth device and method, wherein a partition is arranged below the bottom of the crucible, and after polycrystalline silicon carbide is generated at the bottom of the crucible, the partition is moved downward to form a gas interlayer between the lower surface of the bottom of the crucible and the partition, thereby offsetting the enhanced bottom heat dissipation caused by the higher thermal conductivity of polycrystalline silicon carbide, thereby ensuring the stability of the temperature field inside the solution.
[0006] In the first aspect, the present invention provides a liquid phase crystal growth device, including a cavity, a crucible installed in the cavity, a hollow cylindrical structure installed at the bottom of the crucible, a partition is arranged inside the cylindrical structure, and the lower surface of the partition is connected to a lifting mechanism, the lifting mechanism is used to drive the partition to move up and down between position A and position B along the inner wall of the cylindrical structure and support the partition so that it is fixed at any position between position A and position B, position A is higher than position B; a gas interlayer can be formed between the partition and the lower surface of the bottom of the crucible.
[0007] Furthermore, the lifting mechanism is a telescopic rod, and the output end of the telescopic rod is fixedly connected to the lower surface of the partition. Through the extension and retraction of the output end of the telescopic rod, the partition can slide up and down between position A and position B along the inner wall of the cylindrical structure and be fixed at any position between position A and position B. When the output end of the telescopic rod is extended to the longest, the partition reaches position A, and when the output end of the telescopic rod is retracted to the shortest, the partition reaches position B.
[0008] Further, when the partition is located at position A, the upper surface of the partition is in contact with the lower surface of the bottom of the crucible.
[0009] Furthermore, one or more pores are provided on the side wall of the tubular structure, and at least one pore is located on the side wall of the tubular structure between the bottom of the crucible and position A. During liquid phase growth, nitrogen or argon or other gases need to be introduced into the crystal growth furnace chamber, and the gas can enter the gas interlayer from the chamber through the pores provided on the side wall of the tubular structure between the bottom of the crucible and position A.
[0010] Furthermore, a heat-insulating layer is provided on the outside of the crucible.
[0011] Furthermore, a heating device is provided outside the crucible; preferably, the heating device may be an induction coil.
[0012] Furthermore, it also includes a seed crystal rod, the upper end of which is connected to the pulling and rotating mechanism, and the lower end is used to fix the seed crystal.
[0013] Furthermore, the partition and the cylindrical structure are both made of graphite. Graphite is a porous material, so the partition and the cylindrical structure made of graphite have rich pore structures, and the gas can freely enter and exit from these pores. By utilizing this characteristic, even if no pores are opened on the side wall of the cylindrical structure, when the partition is moved, the gas in the chamber can be replenished into the space between the partition and the bottom of the crucible through the pores to form a gas interlayer.
[0014] In a second aspect, the present invention provides a liquid phase crystal growth method, which uses the above-mentioned liquid phase crystal growth device to introduce gas into the chamber, heat the co-solvent in the crucible, and the seed crystal rod drives the seed crystal to approach the co-solvent for crystal growth. After polycrystals are formed at the bottom of the crucible, gas is introduced into the interlayer; preferably, as polycrystals are continuously formed at the bottom of the crucible, the thickness of the interlayer is gradually increased, and gas is added to the interlayer.
[0015] Furthermore, the gas is selected from nitrogen and / or helium; preferably, the gas introduced into the interlayer is consistent with the gas introduced into the chamber.
[0016] The beneficial effects of the present invention are: The present invention provides a liquid phase crystal growth device and a liquid phase crystal growth method using the device, wherein a gas interlayer is arranged at the bottom of a crucible to reduce heat dissipation at the bottom of the crucible, thereby compensating for enhanced heat dissipation caused by polycrystals, and being able to keep the internal temperature field of the solution stable during a long growth period, thereby controlling the temperature of the crystal growth interface to maintain stability and improving the crystal quality. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] 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.
[0018] Figure 1 This is a photo of polycrystalline silicon carbide at the bottom of the crucible after liquid phase growth.
[0019] Figure 2 It is a schematic diagram of the structure of the liquid phase crystal growth device in Example 2.
[0020] Figure 3 It is a schematic diagram of the structure of the liquid phase crystal growth device in Example 3.
[0021] Figure 4 This is a simulation diagram of the temperature distribution inside the initial solution.
[0022] Figure 5 This is a simulation diagram of the temperature distribution in the cross section of the solution after polycrystal formation.
[0023] Figure 6 This is a simulation diagram of the temperature distribution in the cross section of the solution after polycrystal formation using gas interlayer temperature compensation.
[0024] Figure 7 It is a simulated curve diagram of the temperature distribution at the crystal growth front.
[0025] In the figure, 1-cavity, 2-crucible, 3-cylindrical structure, 4-partition, 5-lifting mechanism, 6-gas interlayer, 7-insulating layer, 8-heating device, 9-pulling and rotating mechanism, 10-seed crystal rod, 11-seed crystal, 12-pore, 13-gas transmission channel. DETAILED DESCRIPTION
[0026] 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.
[0027] Example 1 A liquid phase crystal growth device comprises a cavity 1, a crucible 2 is installed in the cavity 1, a hollow cylindrical structure 3 is installed at the bottom of the crucible 2, a partition 4 is arranged inside the cylindrical structure 3, and a lifting mechanism 5 is connected to the lower surface of the partition 4. The lifting mechanism 5 is used to drive the partition 4 to move up and down between position A and position B along the inner wall of the cylindrical structure 3 and support the partition 4 to be fixed at any position between position A and position B, and position A is higher than position B; a gas interlayer 6 can be formed between the partition 4 and the lower surface of the bottom of the crucible 2.
[0028] Example 2 A liquid phase crystal growth device, comprising a cavity 1, a crucible 2 installed in the cavity 1, a heat preservation layer 7 and a heating device 8 (such as an induction coil, etc.) surrounding the side wall of the crucible 2 are arranged on the outside of the crucible 2 in sequence; a pulling and rotating mechanism 9 is also installed in the cavity 1, and the pulling and rotating mechanism 9 is connected to the upper end of a seed crystal rod 10, and is used to drive the seed crystal rod 10 to rotate or move the seed crystal rod 10 upward or downward, and the lower end of the seed crystal rod 10 is fixed with a seed crystal 11; A hollow cylindrical structure 3 is installed at the bottom of the crucible 2, and a partition 4 is arranged inside the cylindrical structure 3. Both the cylindrical structure 3 and the partition 4 are made of graphite. The lower surface of the partition 4 is connected with a telescopic rod, and the output end of the telescopic rod is fixedly connected to the lower surface of the partition 4. When the output end of the telescopic rod is extended to the longest, the partition 4 reaches position A. When the partition 4 is in position A, the upper surface of the partition 4 contacts the lower surface of the bottom of the crucible 2. When the output end of the telescopic rod is contracted to the shortest, the partition 4 reaches position B; a gas interlayer 6 can be formed between the partition 4 and the lower surface of the bottom of the crucible 2.
[0029] Example 3 A liquid phase crystal growth device, comprising a cavity 1, a crucible 2 installed in the cavity 1, a heat preservation layer 7 and a heating device 8 (such as an induction coil, etc.) surrounding the side wall of the crucible 2 are arranged on the outside of the crucible 2 in sequence; a pulling and rotating mechanism 9 is also installed in the cavity 1, and the pulling and rotating mechanism 9 is connected to the upper end of a seed crystal rod 10, and is used to drive the seed crystal rod 10 to rotate or move the seed crystal rod 10 upward or downward, and the lower end of the seed crystal rod 10 is fixed with a seed crystal 11; A hollow cylindrical structure 3 is installed at the bottom of the crucible 2, and a partition 4 is arranged inside the cylindrical structure 3. The lower surface of the partition 4 is connected to a telescopic rod, and the output end of the telescopic rod is fixedly connected to the lower surface of the partition 4. When the output end of the telescopic rod is extended to the longest, the partition 4 reaches the A position. When the partition 4 is at the A position, the upper surface of the partition 4 contacts the lower surface of the bottom of the crucible 2. When the output end of the telescopic rod is retracted to the shortest, the partition 4 reaches the B position. One or more air holes 12 are opened on the side wall of the tubular structure 3, and at least one air hole 12 is located on the side wall of the tubular structure 3 between the bottom of the crucible 2 and the A position. When the telescopic rod pulls the partition 4 to move downward, the gas in the chamber enters the space between the partition 4 and the lower surface of the bottom of the crucible 2 through the air hole 12, forming a gas interlayer 6.
[0030] Example 4 The liquid phase crystal growth device of the above-mentioned embodiment 1, embodiment 2 or embodiment 3 is used to grow crystals. Taking silicon carbide crystal as an example, a graphite crucible is used, and a solubilizing agent is contained in the graphite crucible. The solubilizing agent is a growth raw material containing Si and a metal element. First, the air in the cavity is replaced with a mixed gas of helium and nitrogen, and then the heating device is turned on to melt the solubilizing agent into a solution, and the seed crystal rod is lowered to make the seed crystal contact with the solution for growth. After a period of time, the output end of the telescopic rod is controlled to shrink, so that the partition moves downward for a distance, and the mixed gas of helium and nitrogen enters the space between the partition and the lower surface of the bottom of the graphite crucible through the cylindrical structure, the pores of the partition itself, or the specially opened pores to form a gas interlayer.
[0031] In other embodiments, the speed of the telescopic rod may also be controlled by a speed regulator so that the partition moves slowly downward during a long crystal growth process until it reaches position B.
[0032] The working process of the liquid phase crystal growth device of Example 2 was analyzed by COMSOL software. A two-dimensional axisymmetric model was adopted. The center temperature of the seed crystal was set to 1900° C. and the internal temperature range of the solution was 1898-1910° C. during the simulation process. Figure 4-6 They are respectively a simulation diagram of the temperature distribution of the initial solution cross section, a simulation diagram of the temperature distribution of the solution cross section after polycrystal formation, and a simulation diagram of the temperature distribution of the solution cross section after polycrystal formation using gas interlayer compensation temperature. The isotherms are 20 equal parts of the solution temperature, i.e., an interval of 0.6° C. It can be seen from the comparison that the temperature field distribution inside the solution remains basically stable using the gas interlayer compensation technology proposed in the present invention. Figure 7 It is the temperature distribution curve of the crystal growth front position (i.e. the bottom of the seed crystal) in three states: initial, after polycrystalline formation, and after polycrystalline formation with gas interlayer temperature compensation. The horizontal axis represents the distance from the seed crystal surface to the center, and the vertical axis represents the temperature. Figure 7It more intuitively reflects that the temperature field distribution of the seed crystal using the growth method of gas interlayer compensation is almost consistent with the initial state, proving that the device and method of the present invention can achieve long-term stable growth of crystals, which is conducive to obtaining high-quality crystals.
[0033] 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 liquid phase crystal growth device, comprising a chamber, characterized in that: The crucible is installed in the cavity, and a hollow cylindrical structure is installed at the bottom of the crucible. A partition is arranged inside the cylindrical structure. The lower surface of the partition is connected to a lifting mechanism. The lifting mechanism is used to drive the partition to move up and down between position A and position B along the inner wall of the cylindrical structure and support the partition so that it is fixed at any position between position A and position B. Position A is higher than position B; a gas interlayer can be formed between the partition and the lower surface of the bottom of the crucible.
2. The liquid phase crystal growth device according to claim 1, characterized in that: The lifting mechanism is a telescopic rod, the output end of which is fixedly connected to the lower surface of the partition, wherein the partition reaches position A when the output end of the telescopic rod is extended to the longest, and reaches position B when the output end of the telescopic rod is contracted to the shortest.
3. The liquid phase crystal growth device according to claim 1, characterized in that: When the partition is located at position A, the upper surface of the partition is in contact with the lower surface of the bottom of the crucible.
4. The liquid phase crystal growth device according to claim 1, characterized in that: One or more air holes are formed on the side wall of the tubular structure, and at least one air hole is located on the side wall of the tubular structure between the bottom of the crucible and the A position.
5. The liquid phase crystal growth device according to claim 1, characterized in that: An insulation layer is provided on the outside of the crucible.
6. The liquid phase crystal growth device according to claim 1, characterized in that: A heating device is arranged on the outside of the crucible.
7. The liquid phase crystal growth device according to claim 1, characterized in that: It also includes a seed crystal rod, the upper end of which is connected to the pulling and rotating mechanism, and the lower end of which is used to fix the seed crystal.
8. The liquid phase crystal growth device according to claim 1, characterized in that: The partitions and the cylindrical structure are both made of graphite.
9. A liquid phase crystal growth method, characterized in that: Using the liquid phase crystal growth device as described in any one of claims 1 to 8, gas is introduced into the chamber to heat the solvent in the crucible, and the seed crystal rod drives the seed crystal to approach the solvent for crystal growth. After polycrystals are formed at the bottom of the crucible, gas is introduced into the interlayer.
10. The liquid phase crystal growth method according to claim 9, characterized in that: The gas is selected from nitrogen and / or helium.