Crystal growth device with multiple deposition sites and manufacturing process thereof

Abstract

The invention discloses a crystal growth device with a plurality of deposition sites, which mainly comprises a heating cavity internally provided with a rotatable support column; the heating bearing assembly is connected to the supporting column, the heating bearing assembly comprises a crucible, a filter and a plurality of deposition sites, and the crucible is provided with a plurality of source materials; the heat generator is arranged in the heating cavity and is used for providing the heat energy to the heating cavity; and a plurality of rigid devices as auxiliary heaters or deposition radiators, so that at least one thermal field inside the heating cavity forms a 2D or 3D thermal gradient. The invention further discloses a crystal growth process with a plurality of deposition sites. By forming 2D or 3D thermal gradients over a plurality of deposition sites, compound crystals with few defects are stably and rapidly manufactured.

Description

Technical Field

[0001] The present invention relates to a crystal growth apparatus and a process thereof, and more particularly, to a crystal growth apparatus and a process thereof for growing high-quality compound crystals of silicon carbide, which stably and rapidly fabricate compound crystals with few defects by forming 2D or 3D thermal gradients at a plurality of deposition sites. Background Art

[0002] Crystal growth is a process in which a pre-existing crystal becomes larger as more molecules or ions are added to positions in the lattice. A crystal is defined as atoms, molecules, or ions arranged in an ordered repeating pattern, i.e., a lattice, that extends in all three spatial dimensions. Thus, crystal growth differs from droplet growth in that during growth, molecules or ions must fall into the correct lattice positions in order to grow an ordered crystal.

[0003] Widely used compound crystals include crystals such as silicon carbide (SiC), gallium nitride (GaN), aluminum nitride (AlN), and gallium oxide (Ga2O3). Most compound crystals have semiconductor materials and excellent thermal conductivity and chemical stability. From the perspective of transistor characteristics such as dielectric breakdown characteristics and saturation drift velocity, they are highly anticipated as materials for next-generation semiconductor components. Compound crystal growth techniques can be roughly divided into three types: physical vapor transport (PVT), high-temperature chemical vapor deposition (HTCVD), and solution growth.

[0004] For the growth of compound crystal GaN crystals, under high temperature and high pressure, NH 3 Needle-shaped GaN is grown through liquid Ga; GaN can also be grown using chemical vapor deposition (CVD); high-temperature growth has obtained high-quality GaN, and it is still the most common buffer layer growth method at present. Although the technology using buffer layers has improved the quality of GaN epitaxy, there is still a certain gap compared with GaN components grown directly on GaN substrates.

[0005] In addition to being more expensive than Si substrates, compound crystal SiC substrates also have problems such as insufficient reduction of defects and insufficient high quality of single crystal substrates. When silicon carbide is heated under normal pressure, it sublimes at a temperature of around 2000 °C, so crystal growth methods such as the Czochralski method (CZ method) or the floating zone method (FZ method) cannot be used. Therefore, current silicon carbide single crystals are mainly manufactured by sublimation methods led by the modified Rayleigh method. The sublimation method is a common method for mass-producing silicon carbide single crystals. However, even when using silicon carbide single crystals obtained by the sublimation method to fabricate power devices, their characteristics may not be considered sufficient. The reason is that it is difficult to reduce the defects of silicon carbide single crystals. Crystal growth by the sublimation method is a precipitation phenomenon from the gas phase, with a slow growth rate and difficult temperature management in the reaction space.

[0006] Therefore, recently, a compound crystal crystallization growth method using the solution method has attracted attention. The solution method for compound crystals is roughly divided into the following four types: (a) Traveling Solvent Method (TSM), (b) Slow Cooling Technique (SCT), (c) Vapor Liquid Solid (VLS), and (d) Top Seeded Solution Growth (TSSG). The growth of compound crystals by the solution method of conventional methods uses the temperature gradient formed throughout the solution to grow single crystals. Many compound crystals themselves do not melt under normal pressure. In this solution method, the crystallization growth of compound crystals is carried out in a state extremely close to thermal equilibrium. Therefore, compared with compound crystals obtained by the sublimation method, compound crystals with fewer defects can be obtained. However, this conventional crystal growth method has the following problem: the composition of raw materials changes over time, and it is difficult to continuously and stably carry out single crystal growth of compound crystals for a long time.

[0007] In view of the above problems, it is necessary to propose a crystal growth device and its manufacturing process that can stably and rapidly manufacture diverse compound crystals with few defects, including silicon carbide (SiC), gallium nitride (GaN), aluminum nitride (AlN), and gallium oxide (Ga 2 O 3 ) etc., by forming 2D or 3D thermal gradients at multiple deposition sites. Summary of the Invention

[0008] The main object of the present invention is to provide a crystal growth apparatus with multiple deposition sites, which can form a 2D or 3D thermal gradient at multiple deposition sites through an auxiliary heater or a deposition radiator and a plurality of thermal field adjustment components, and stably and rapidly manufacture compound crystals such as silicon carbide (SiC), gallium nitride (GaN), aluminum nitride (AlN), and gallium oxide (Ga 2 O 3 )

[0009] The secondary object of the present invention is to provide a crystal growth process with multiple deposition sites, mainly by forming a single or multiple different thermal fields in a heating cavity, enabling the source material to evaporate in these thermal fields, and with the assistance of a filter, stably and rapidly manufacturing compound crystals such as silicon carbide (SiC), gallium nitride (GaN), aluminum nitride (AlN), and gallium oxide (Ga 2 O 3 )

[0010] To achieve the above main object, the present invention provides a crystal growth apparatus with multiple deposition sites, comprising:

[0011] A heating cavity internally provided with a rotatable support pillar;

[0012] At least one heating and carrying component connected to the support pillar, the heating and carrying component including a crucible, a filter, a plurality of deposition sites, and the crucible having a plurality of source materials;

[0013] A heat generator disposed inside the heating cavity for providing heat energy to the heating cavity; and

[0014] A plurality of rigid devices serving as an auxiliary heater or a deposition radiator to form a 2D or 3D thermal gradient in at least one thermal field inside the heating cavity.

[0015] According to a feature of the present invention, the heat generator is a radio frequency heating coil, forming a single or multiple different thermal fields in the heating cavity, and the source materials of the heating and carrying component evaporate in these thermal fields, and the vapor reaches the deposition sites through the filter.

[0016] According to a feature of the present invention, it further includes a plurality of insulators disposed inside the heating cavity for protecting a cylindrical or rectangular water jacket on the surface of the heating cavity.

[0017] According to a feature of the present invention, it further includes a plurality of thermal field adjustment components disposed inside the heating cavity and located between the heating and carrying components, so that each heating and carrying component of the heating cavity is in a thermal field with a different thermal gradient.

[0018] According to a feature of the present invention, the material of the crucible is one or a combination selected from an alloy, a metal, a ceramic, or a compound material.

[0019] According to a feature of the present invention, a gas is introduced into the heating cavity, and the gas is selected from Ar, N 2 , CO, CO 2 and one of the doping gases, and the pressure range of the gas is: 10 -6 mbar to 10 atm.

[0020] According to a feature of the present invention, the state of the source material can be a liquid phase, a solid phase, a gas phase, and a mixed phase, and the deposition sites have a powdery crystal as a nucleation point, and the powdery crystal is selected from SiC, GaN, AlN, or Ga 2 O 3 one of the powdery crystals.

[0021] According to a feature of the present invention, the top, middle, and bottom viewports of the heating cavity are equipped with infrared pyrometers to detect the temperature of the heating cavity.

[0022] According to a feature of the present invention, the filter is used to regulate the gas of the source material that sublimes when heated, and the filtration rate will vary with the thermal gradient of different thermal fields.

[0023] To achieve the above secondary objectives, the present invention proposes a crystal growth process with multiple deposition sites, which uses a crystal growth device with multiple deposition sites, including the following steps:

[0024] Providing a plurality of source materials on a crucible of a heating and carrying component in a heating cavity;

[0025] Providing a thermal energy to the heating cavity to form one or more different thermal fields, so that the source materials of the heating and carrying component evaporate in the thermal fields, and the vapor passes through a filter to reach the deposition sites; and

[0026] Forming a 2D or 3D thermal gradient in the thermal field inside the heating cavity through an auxiliary heater or a deposition radiator.

[0027] In summary, a crystal growth device and process with multiple deposition sites according to the present invention have the following effects:

[0028] 1. The diverse crystal growth device is easy to manufacture and integrate;

[0029] 2. The heating cavity forms one or more different thermal fields;

[0030] 3. Multiple deposition sites form a 2D or 3D thermal gradient;

[0031] 4. Stably and rapidly fabricate compound crystals with few defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] To make the above and other objects, features, and advantages of the present invention more obvious and understandable, several preferred embodiments are specifically given below and described in detail in conjunction with the accompanying drawings as follows.

[0033] Figure 1 It is a main structural diagram of a crystal growth device with multiple deposition sites according to the present invention.

[0034] Figure 2 It is a schematic diagram of a heating and loading component of a crystal growth device with multiple deposition sites according to the present invention.

[0035] Figure 3 It is a flowchart of a crystal growth process with multiple deposition sites of the present invention.

[0036] Figure 4 It is a schematic photo of these source materials in the heating and loading component of the present invention.

[0037] Figure 5 It is a schematic photo of these deposition sites in the heating and loading component of the present invention.

[0038] Figure 6 It is a schematic photo of the compound crystal in the heating and loading component of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] Although the present invention can be embodied in different forms of embodiments, the embodiments shown in the drawings and described herein are considered to be preferred embodiments of the present invention. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the drawings are considered as an example of the present invention, a non-limiting illustrative embodiment, and the scope of the present invention is only defined by the claims. Features illustrated or described in connection with one illustrative embodiment can be combined with features of other embodiments. Such modifications and variations will be included within the scope of the present invention.

[0040] Now please refer to Figure 1 , which is a schematic side view of the structure of an embodiment of a crystal growth device 100 with multiple deposition sites. The crystal growth device 100 with multiple deposition sites mainly includes: a heating cavity 10, at least one heating and loading component 20, a plurality of rigid devices 30-1, 30-2, 30-3, 30-4, and a heat generator 40.

[0041] Inside the heating cavity 10, a rotatable support pillar 12 is provided. The heating and carrying assembly 20 is connected to the support pillar 12 and is arranged at different positions above and below the support pillar 12. Through the rotatable support pillar 12, the heating and carrying assembly 20 can rotate inside the heating cavity 10 and control the rotation speed. A cylindrical or rectangular water jacket 14 is arranged on the surface of the heating cavity 10, and the water jacket 14 is used to reduce the temperature of the outer surface of the heating cavity 10. For example, there are at least 6 groups of the heating and carrying assemblies 20, divided into 3 groups above and 3 groups below, and are connected to the support pillar 12.

[0042] These rigid devices 30-1, 30-2, 30-3, 30-4, as auxiliary heaters or deposition radiators, are used to form a 2D or 3D thermal gradient in at least one thermal field 28 inside the heating cavity 10. That is, these rigid devices 30-1, 30-2, 30-3, 30-4 can be connected to an external heater to regulate the thermal field distribution of the heating cavity 10; or, these rigid devices 30-1, 30-2, 30-3, 30-4 are made of materials with rapid heat dissipation, such as carbon-containing compounds, to regulate the thermal field distribution of the heating cavity 10.

[0043] The heat generator 40 is arranged inside the heating cavity 10 and is used to provide a thermal energy to the heating cavity 10 to form a single or multiple different thermal fields 28 in the heating cavity 10. In one embodiment, the heat generator 40 surrounds the inside of the heating cavity 10, mainly including an electrothermal heating coil, an electromagnetic induction coil, a radio frequency heating coil, a microwave heat conduction source, etc. The arrow 42 indicates the heat dissipation direction.

[0044] In one embodiment, the crystal growth device 100 with multiple deposition sites uses the solution method to form compound crystals. Since many compound crystals are difficult to melt under normal pressure, the heating cavity 10 requires a very high temperature. In this solution method, the crystallization growth of compound crystals is carried out in a state very close to thermal equilibrium. Therefore, compared with the compound crystals obtained by the sublimation method, compound crystals with fewer defects can be obtained. For example, in the manufacturing method of silicon carbide compound crystals using the solution method, in a silicon (Si) melt in a graphite crucible, carbon (C) is dissolved from the high-temperature part below the crucible, and a silicon carbide seed crystal is brought into contact with this Si-C melt, and epitaxial growth is carried out on the silicon carbide seed crystal to obtain silicon carbide compound crystals.

[0045] The heating and carrying assembly 20 includes a crucible 22, a filter 24, and a plurality of deposition sites 26-1, 26-2, 26-3. The crucible has a plurality of source materials 23. The material of the crucible 22 is selected from one of alloy, metal, ceramic, and compound materials. The crucible 22 is used to contain silicon carbide (SiC), gallium nitride (GaN), aluminum nitride (AlN), and gallium oxide (Ga 2 O3 ) These source materials 23 of compound crystals, such as, will melt or sublime when heated. These deposition sites 26-1, 26-2, 26-3 can be set to install seeds, supply the vapor or sublimation gas generated by the melting of these source materials 23, and grow specific compound crystals on these seeds. The filter 24 is used to regulate the vapor or sublimation gas generated by the heating and melting of these source materials 23, and the filtration rate will vary with the thermal gradient of different thermal fields.

[0046] The state of the source material 23 can be liquid phase, solid phase, gas phase and mixed phase, and these deposition sites 26-1, 26-2, 26-3 have a powdery crystal as a nucleation point, and the powdery crystal is selected from SiC, GaN, AlN and Ga 2 O 3 One of the powdery crystals.

[0047] In one embodiment, these source materials 23 are preferably high-purity silicon carbide powder raw materials, placed in the crucible 22, and heated to above 1,800 °C in an environment of negative pressure or inert gas (low-pressure argon), so that the silicon carbide powder raw material decomposes and sublimes into Si, C, Si 2 C and SiC 2 gas. In another embodiment, an Si melt can be formed in the crucible 22, but since the solubility of C in the Si melt is about 1 at%, which is extremely small, a transition metal or the like is added to the Si melt to make C easily soluble. The transition metal includes low-melting-point metals such as Ti, Cr, Ni, Fe, Al, Sn, Ga, or various rare earth elements, etc.

[0048] In one embodiment, the heat generator 40 is heated by a radio frequency induction coil and is disposed in the region of the heating cavity 10 to heat the crucible 22 of the heating and loading assembly 20. At the same time, by controlling the pressure of the heating cavity 10, these source materials 23 of the heating and loading assembly 20 melt or sublime in these thermal fields 28, and the vapor or sublimation gas generated by melting passes through the filter 24 to reach these deposition sites 26-1, 26-2, 26-3. In one embodiment, by controlling the pressure of the heating cavity 10 to a low vacuum degree, these source materials 23 of the heating and loading assembly 20 sublime in these thermal fields 28, forming a chemical vapor phenomenon and depositing on these deposition sites 26-1, 26-2, 26-3.

[0049] The crystal growth device 100 with multiple deposition sites further includes a plurality of insulators 60-1, 60-2, 60-3, 60-4, which are disposed inside the heating cavity 10 and between the heating and loading assemblies 20 to protect the cylindrical or rectangular water jacket 14 from overheating and melting.

[0050] It should be noted that, in order to provide the heating cavity 10 to form a single or multiple different thermal fields 28, the crystal growth device 100 with multiple deposition sites further includes a plurality of thermal field adjustment components 70-1, 70-2, which are arranged inside the heating cavity 10 and located between the heating and supporting components 20, so that each of the heating and supporting components 20 of the heating cavity 10 is in the thermal field 28 with different thermal gradients.

[0051] The heating cavity 10 has a connected gas pipeline through which a gas can be introduced to make the cavity in the atmosphere of the gas. Preferably, the gas is selected from one of Ar, N 2 , CO, CO 2 and a doping gas. The gas pressure range of the heating cavity 10 is: 10 -6 mbar to 10 atm.

[0052] Since each of the heating and supporting components 20 of the heating cavity 10 needs to be in the thermal field 28 with different thermal gradients, infrared pyrometers 50 are provided at the top, middle and bottom of the heating cavity 10 to detect the temperature of the heating cavity 10. By understanding the temperature distribution, a central control module (not shown) of the crystal growth device 100 with multiple deposition sites controls the operations of the heat generator 40, the rigid devices 30-1, 30-2, 30-3, 30-4 and the thermal field adjustment components 70-1, 70-2, so that each of the heating and supporting components 20 of the heating cavity 10 can be precisely in the thermal field 28 with different thermal gradients. That is to say, in addition to the heat generator 40 providing heat to the heating cavity 10, the rigid devices 30-1, 30-2, 30-3, 30-4 can be selected as auxiliary heaters or deposition radiators, and the thermal field adjustment components 70-1, 70-2 can be appropriately activated to adjust each of the heating and supporting components 20 of the heating cavity 10 to be in the thermal field 28 with different thermal gradients.

[0053] Figure 2 It is a schematic diagram of the heating and supporting components of the crystal growth device with multiple deposition sites according to the present invention. In the heating cavity 10, there are 3 groups of the heating and supporting components 20 each on the upper and lower sides. The 3 groups of heating and supporting components on the upper side are 20-U1, 20-U2, 20-U3, and the 3 groups of heating and supporting components on the lower side are 20-L1, 20-L2, 20-L3. It should be noted that all the heating and supporting components will have their own crucibles 22, the source materials 23, filters 24, and a plurality of deposition sites 26 (26-1, 26-2, 26-3 are represented by 26).

[0054] Now please refer to Figure 3 and in conjunction with Figure 1, which is a flowchart of the crystal growth process for multiple deposition sites of the present invention. The present invention proposes a crystal growth process with multiple deposition sites, which uses a crystal growth device with multiple deposition sites and includes the following steps:

[0055] Step S10: Provide a plurality of source materials on a crucible of a heating carrier assembly in a heating cavity;

[0056] Step S20: Provide a thermal energy to the heating cavity to form one or more different thermal fields, so that the source materials of the heating carrier assembly are evaporated in these thermal fields, and the vapor reaches the deposition sites through a filter; and

[0057] Step S30: Provide an auxiliary heater or a deposition radiator to form a 2D or 3D thermal gradient in at least one thermal field inside the heating cavity.

[0058] Now please refer to Figure 4 , 5, 6. Figure 4 is a photo schematic diagram of the source materials in the heating carrier assembly of the present invention. The state of the source materials 23 can be liquid phase, solid phase, gas phase, and mixed phase. Figure 5 is a photo schematic diagram of the deposition sites in the heating carrier assembly of the present invention, with a powdery crystal as a nucleation point. Figure 6 is a photo schematic diagram of the compound crystal in the heating carrier assembly of the present invention. Since there are multiple different thermal fields 28 in the heating cavity 10, the crystal sizes of the compound crystals are different. The crystal pattern C formed in the relatively cold zone is shown above, and the crystal pattern H formed in the relatively hot zone is shown below. And the crystal size of the crystal pattern C formed in the relatively cold zone is smaller than the crystal size of the crystal pattern H formed in the relatively hot zone.

[0059] In summary, a crystal growth device and process with multiple deposition sites of the present invention have the following effects:

[0060] 1. The diverse crystal growth device is easy to manufacture and integrate;

[0061] 2. The heating cavity forms one or more different thermal fields;

[0062] 3. A 2D or 3D thermal gradient is formed on multiple deposition sites;

[0063] 4. Various compound crystals can be stably and rapidly manufactured.

[0064] Although the present invention has been disclosed in the foregoing preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. As explained above, various forms of corrections and changes can be made without destroying the spirit of this invention. Therefore, the scope of protection of the present invention shall be subject to that defined by the appended patent application scope.

Claims

1. A crystal growth device with multiple deposition sites, characterized in that, mainly includes: a heating cavity with a rotatable support pillar disposed therein; at least one heating and carrying component connected to the support pillar, the heating and carrying component includes a crucible, a filter, a plurality of deposition sites, and the crucible has a plurality of source materials; a heat generator disposed inside the heating cavity for providing heat energy to the heating cavity; and a plurality of rigid devices serving as an auxiliary heater or a deposition radiator to form a 2D or 3D thermal gradient in at least one thermal field inside the heating cavity.

2. The crystal growth device with multiple deposition sites according to claim 1, characterized in that, the heat generator is a radio frequency heating coil, forming a single or multiple different thermal fields in the heating cavity, and the source materials of the heating and carrying component evaporate in these thermal fields, and the vapor passes through the filter to reach the deposition sites.

3. The crystal growth device with multiple deposition sites according to claim 1, characterized in that, further includes a plurality of insulators disposed inside the heating cavity for protecting a cylindrical or rectangular water jacket on the surface of the heating cavity.

4. The crystal growth device with multiple deposition sites according to claim 1, characterized in that, further includes a plurality of thermal field adjustment components disposed inside the heating cavity and located between the heating and carrying components to make each heating and carrying component of the heating cavity be in a thermal field with different thermal gradients.

5. The crystal growth device with multiple deposition sites according to claim 1, characterized in that, the material of the crucible is selected from one or a combination of an alloy, a metal, a ceramic or a compound material.

6. The crystal growth device with multiple deposition sites according to claim 1, characterized in that, A gas is introduced into the heating chamber, and the gas is selected from Ar, N 2 , CO, CO 2 and one of the doping gases, and the pressure range of the gas is: 10 -6 mbar to 10 atm.

7. The crystal growth device with multiple deposition sites according to claim 1, characterized in that, the state of the source material can be liquid phase, solid phase, gas phase and mixed phase, and the deposition sites have a powdered crystal as a nucleation point, and the powdered crystal is selected from one of SiC, GaN, AlN or Ga2O3 powdered crystals.

8. The crystal growth device with multiple deposition sites according to claim 1, characterized in that, the top, middle and bottom viewports of the heating cavity are provided with an infrared pyrometer to detect the temperature of the heating cavity.

9. The crystal growth device with multiple deposition sites according to claim 2, characterized in that, the filter is used to regulate the gas of the source material sublimated by heat, and the filtering speed is different with the thermal gradient of different thermal fields.

10. A crystal growth process with multiple deposition sites, which uses the crystal growth device with multiple deposition sites of claim 1, characterized in that, includes the following steps: providing a plurality of source materials on a crucible of a heating and carrying component in a heating cavity; providing a heat energy to the heating cavity to form a single or multiple different thermal fields, so that the source materials of the heating and carrying component evaporate in these thermal fields, and the vapor passes through a filter to reach the deposition sites; and Provide an auxiliary heater or a deposition heat sink so that the thermal field inside the heating cavity forms a 2D or 3D thermal gradient.

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