Methods for reducing volatiles during gallium oxide crystal growth, seed crystal pulling devices and applications

Abstract

This application relates to the field of gallium oxide crystal technology, specifically disclosing a method for reducing volatiles generated during gallium oxide crystal growth, a seed crystal pulling device, and its application. The method for reducing volatiles generated during gallium oxide crystal growth includes a seed crystal pulling device. The device includes an inner seed crystal rod, the bottom of which is used to fix the seed crystal. An outer seed crystal rod is fitted onto the outer periphery of the inner seed crystal rod. The outer seed crystal rod is a cylinder with an open top, a closed bottom, and a hollow interior. The inner diameter of the outer seed crystal rod is larger than the diameter of the inner seed crystal rod. A through-hole adapted to the seed crystal is formed at the bottom of the outer seed crystal rod. The inner seed crystal rod moves along the length of the outer seed crystal rod, driving the seed crystal to move within the through-hole. Before crystal pulling, the interaction between the outer and inner seed crystal rods causes the volatiles adhering to the outer periphery of the seed crystal to detach, solving the problem of volatiles affecting the crystal formation rate. Simultaneously, the seed crystal pulling device also has the advantages of simple structure and low cost, creating high economic benefits.

Description

Technical Field

[0001] This application relates to the field of gallium oxide crystal technology, and in particular to a method for reducing gallium oxide crystal growth volatiles, a seed crystal pulling device, and its application. Background Technology

[0002] Gallium oxide (GaO) crystal is a transparent oxide semiconductor material with advantages such as ultra-wide bandgap, low power consumption, and high stability, making it promising for applications in optoelectronic devices. The main methods for growing GaO crystals include the Czochralski method and the mode-guided method.

[0003] The Czochralski method involves heating and melting gallium oxide raw material, adjusting the temperature inside the crystal growth furnace to ensure the top of the molten gallium oxide is in a supercooled state, then using a seed crystal to fuse with the surface of the molten gallium oxide. The seed crystal is then pulled up, allowing the top molten gallium oxide to crystallize on it. This process is repeated, with the seed crystal being pulled up again, and the molten gallium oxide continuing to crystallize, thus growing a gallium oxide crystal on the seed crystal.

[0004] The guide mold method involves heating and melting gallium oxide raw material inside a mold. The molten gallium oxide rises to the top of the mold under the action of capillaries, and the seed crystal contacts the molten gallium oxide at the top of the mold. Then the seed crystal is pulled up, and the molten gallium oxide crystallizes to form a gallium oxide crystal with the same shape as the mold.

[0005] However, regardless of whether gallium oxide crystals are prepared by the Czochralski method or the guided method, volatiles are inevitably generated after the gallium oxide material is added to the molten material. These volatiles can easily lead to polycrystalline gallium oxide crystals, reducing the crystallization rate of gallium oxide crystal growth. Summary of the Invention

[0006] In the preparation of gallium oxide crystals, in order to reduce the influence of gallium oxide crystal growth volatiles on the crystallization rate, this application provides a method for reducing gallium oxide crystal growth volatiles, a seed crystal pulling device, and its application.

[0007] In a first aspect, this application provides a seed crystal pulling device for reducing gallium oxide crystal growth volatiles, employing the following technical solution:

[0008] A seed crystal pulling device for reducing volatiles during gallium oxide crystal growth includes an inner seed crystal rod, the bottom end of which is used to fix the seed crystal. An outer seed crystal rod is fitted onto the outer circumferential surface of the inner seed crystal rod. The outer seed crystal rod is a cylindrical shape with an open top, a closed bottom, and a hollow interior. The inner diameter of the outer seed crystal rod is larger than the diameter of the inner seed crystal rod. A through hole adapted to the seed crystal is opened at the bottom end of the outer seed crystal rod. The inner seed crystal rod moves along the length of the outer seed crystal rod and drives the seed crystal to move within the through hole.

[0009] During the gallium oxide crystal preparation process, the applicant discovered that even with a volatile matter removal system installed in the crystal growth furnace, a portion of the volatiles still adhered to the outer surface of the seed crystal due to the large amount of volatiles present, and these volatiles were filamentous. During crystal pulling, the detached volatiles easily entered the molten gallium oxide, introducing impurities and reducing the crystallization rate of the gallium oxide crystal. Based on this, the applicant conducted extensive research.

[0010] Before crystal pulling, the seed crystal is mounted on the inner rod of the seed crystal. Then, the outer rod of the seed crystal moves the seed crystal within the through-hole. When the volatiles come into contact with the bottom wall of the outer rod, force is applied to the inner rod, causing the volatiles to detach. The detached volatiles remelt and evaporate. Since the amount of volatiles at this point is small, they are unlikely to re-adhere to the outer surface of the seed crystal, thus solving the problem of volatiles adhering to the outer surface of the seed crystal and affecting the crystal formation rate.

[0011] Optionally, a limiting member is provided between the outer seed crystal rod and the inner seed crystal rod to reduce the shaking of the inner seed crystal rod.

[0012] Because the seed crystal is fixed at the bottom of the inner seed crystal rod, and the inner diameter of the outer seed crystal rod is larger than its diameter, when the inner seed crystal rod moves the seed crystal within the through-hole, any wobbling within the outer seed crystal rod will inevitably exert a force on the seed crystal, potentially causing it to bend or fall off. The limiting component, by limiting the movement of the inner seed crystal rod within the outer seed crystal rod, reduces this wobbling and improves the stability of the inner seed crystal rod during use.

[0013] In one embodiment, the limiting element is a bearing. Alternatively, as needed, the limiting element can be a limiting ring, at least two limiting blocks arranged circumferentially along the outer rod of the seed crystal, etc., to reduce the wobbling of the inner rod of the seed crystal.

[0014] In one embodiment, the limiting member is fixed to the inner wall of the seed crystal outer rod. Alternatively, the limiting member can be fixed to the outer wall of the seed crystal inner rod as needed.

[0015] In one embodiment, the number of limiting members is three, and the three limiting members are evenly arranged along the length direction of the seed crystal outer rod. Alternatively, the number of limiting members can be set to one, two, four, five, six, etc., as needed.

[0016] Optionally, the diameter of the seed crystal inner rod is larger than the diameter of the through hole.

[0017] Since the inner diameter of the seed crystal outer rod is larger than the outer diameter of the seed crystal, and the diameter of the seed crystal inner rod is larger than the diameter of the through hole, the bottom wall of the seed crystal outer rod can limit the movement distance of the seed crystal inner rod. Moreover, when the bottom end of the seed crystal inner rod and the bottom of the seed crystal outer rod come into contact, moving the seed crystal outer rod can drive the seed crystal inner rod and the seed crystal to move synchronously, which facilitates subsequent crystal pulling, shoulder formation, and equal diameter growth using a seed crystal pulling device.

[0018] Optionally, the bottom wall of the seed crystal outer rod is fixed with an annular protrusion with a right-angled triangular cross-section at the through hole. The end of the annular protrusion away from the bottom wall of the seed crystal outer rod is a spike end, which is in contact with the outer peripheral surface of the seed crystal.

[0019] The volatiles adhering to the outer surface of the seed crystal are filamentous, with one end attached to the seed crystal's outer surface and the other end suspended. If the volatiles tilt towards the outer rod of the seed crystal, the outer rod will initially contact the suspended end of the volatiles. The bottom wall of the outer rod applies force to the suspended end of the volatiles, causing them to easily burst and scatter in all directions. As the seed crystal continues to move, the bottom wall of the outer rod contacts the end of the volatiles, causing the volatiles to detach from the outer surface of the seed crystal.

[0020] An annular protrusion with a spiked end is provided on the outer rod of the seed crystal. If the volatile material is tilted towards the outer rod of the seed crystal, the spiked end of the annular protrusion contacts the volatile material connection end, and the spiked end of the annular protrusion applies force to the volatile material connection end. The volatile material is forced to fall off the outer peripheral surface of the seed crystal, reducing the possibility of the volatile material exploding and scattering in all directions.

[0021] Optionally, the seed crystal outer rod is provided with an outer lifting member for moving it, and / or,

[0022] The seed crystal inner rod is provided with an inner lifting member for moving it.

[0023] An external lifting component is installed on the outer rod of the seed crystal to facilitate the movement of the outer rod and to facilitate the subsequent synchronous movement of the inner rod and the seed crystal by the outer rod.

[0024] An inner lifting component is installed on the inner rod of the seed crystal to facilitate the movement of the seed crystal within the through hole, thereby facilitating the detachment of volatiles from the outer periphery of the seed crystal.

[0025] Optionally, both the inner and outer seed crystal rods are made of high-temperature and oxidation-resistant materials.

[0026] Optionally, the high-temperature and oxidation-resistant material is one of iridium, alumina ceramic, or zirconium oxide ceramic.

[0027] Since the melting temperature of gallium oxide raw material reaches 1740-1820℃, and both the inner and outer seed rods are made of high-temperature and oxidation-resistant materials, the stability and lifespan of the seed crystal pulling device are improved.

[0028] Secondly, this application provides an application of the above-mentioned seed crystal pulling device for reducing gallium oxide crystal growth volatiles, employing the following technical solution:

[0029] The above-described application of the seed crystal pulling device for reducing volatiles during gallium oxide crystal growth, specifically its application in gallium oxide Czochralski crystal growth and gallium oxide guided-mode crystal growth.

[0030] Thirdly, this application provides a method for reducing volatiles generated during gallium oxide crystal growth, employing the following technical solution:

[0031] A method for reducing gallium oxide crystal growth volatiles includes the seed crystal pulling device for reducing crystal growth volatiles described above.

[0032] Optional steps include the following:

[0033] S1. Install the seed crystal at the bottom of the inner rod of the seed crystal;

[0034] S2. Heat the gallium oxide raw material to melt it, and obtain molten gallium oxide;

[0035] S3. Use the inner rod of the seed crystal to drive the seed crystal to move back and forth in the through hole, so that the volatiles adhering to the outer peripheral surface of the seed crystal will fall off.

[0036] S4. Bring the bottom of the inner rod of the seed crystal to contact the bottom of the outer rod of the seed crystal, so that the seed crystal extends out of the outer rod of the seed crystal;

[0037] S5. Move the outer rod of the seed crystal downwards, so that the outer rod of the seed crystal drives the seed crystal and the inner rod of the seed crystal to move downwards synchronously. Then perform welding, crystal pulling, shoulder formation, equal diameter growth, and demolding.

[0038] By adopting the above technical solution, before crystal pulling, the volatiles on the outer periphery of the seed crystal are removed by using a seed crystal pulling device, thereby reducing the introduction of volatiles on the outer periphery of the seed crystal into the gallium oxide crystal and improving the crystallization rate and quality of gallium oxide crystal growth.

[0039] In summary, this application includes at least one of the following beneficial technical effects:

[0040] 1. The method for reducing volatiles during gallium oxide crystal growth in this application utilizes the cooperation of the outer and inner seed crystal rods before crystal pulling to remove volatiles adhering to the outer periphery of the seed crystal, thus solving the problem of volatiles adhering to the outer periphery of the seed crystal affecting the crystal formation rate. Furthermore, the seed crystal pulling device of this application also has the advantages of simple structure and low cost, creating significant economic benefits.

[0041] 2. The inner diameter of the seed crystal outer rod is larger than the outer diameter of the seed crystal, and the diameter of the seed crystal inner rod is larger than the diameter of the through hole. Through the interaction of the seed crystal outer rod, the seed crystal inner rod, and the through hole, the bottom wall of the seed crystal outer rod limits the movement distance of the seed crystal inner rod. This allows the seed crystal outer rod to drive the seed crystal inner rod and the seed crystal to move synchronously, facilitating subsequent crystal pulling, shoulder formation, and equal-diameter growth. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of volatiles bonded to the outer surface of the seed crystal.

[0043] Figure 2 This is a schematic diagram of the seed crystal pulling device in Example 1.

[0044] Figure 3 This is a partial cross-sectional view of the limiting member in Embodiment 1.

[0045] Figure 4 This is a partial cross-sectional view of Example 2 to show the annular spikes.

[0046] Figure 5 This is a partial cross-sectional view of the annular protrusion in Embodiment 3.

[0047] Explanation of reference numerals in the attached diagram: 1. Seed crystal; 2. Inner rod of seed crystal; 3. Outer rod of seed crystal; 31. Through hole; 32. Annular spike; 33. Annular protrusion; 4. Limiting component; 5. Inner lifting component; 6. Outer lifting component. Detailed Implementation

[0048] The following is in conjunction with the appendix Figure 1-5 This application will be described in further detail.

[0049] In preparing gallium oxide crystals, the applicant first places gallium oxide raw material into a mold within a crucible, then heats and melts it to obtain molten gallium oxide. Next, a seed crystal pulling device is used to extend seed crystal 1 downwards above the mold, fusing seed crystal 1 with the molten gallium oxide at the top of the mold. Then, seed crystal 1 is pulled up to begin crystal growth. Afterwards, shoulder formation, constant diameter growth, and demolding are performed to obtain the gallium oxide crystal.

[0050] The applicant discovered during the preparation process that volatiles generated after adding gallium oxide to the molten material diffused freely within the crystal growth furnace and easily deposited throughout the furnace. Even with a volatiles removal system installed in the crystal growth furnace, the high melting temperature of gallium oxide (1740-1820℃) resulted in a large amount of volatiles. Figure 1However, some volatiles still adhere to the outer surface of seed crystal 1, and the amount of volatiles adhering to the outer surface of seed crystal 1 increases with the continuous accumulation of volatiles. Further observation of the volatiles revealed that they appear as filaments and are easily detached upon impact. During crystal pulling, the detached volatiles easily introduce impurities, thereby reducing the crystallization rate of gallium oxide crystal growth and affecting the quality of gallium oxide crystals.

[0051] Example 1

[0052] A seed crystal pulling device for reducing volatiles during gallium oxide crystal growth. The seed crystal pulling device is used in the fabrication of gallium oxide crystals; specifically, it is used to fix a seed crystal 1. (Refer to...) Figure 2-3 The seed crystal pulling device includes an inner seed crystal rod 2 and an outer seed crystal rod 3. The inner seed crystal rod 2 is made of a high-temperature and oxidation-resistant material; in this embodiment, the high-temperature and oxidation-resistant material is zirconia ceramic. The cross-section of the inner seed crystal rod 2 is circular, and the seed crystal 1 is fixed at the bottom end of the inner seed crystal rod 2.

[0053] Reference Figure 2-3 The seed crystal outer rod 3 is also made of zirconia ceramic material. The seed crystal outer rod 3 is a cylinder with an open top and bottom and a hollow interior. The seed crystal inner rod 2 is fitted inside the seed crystal outer rod 3 and slidably connected to it, meaning the seed crystal inner rod 2 can reciprocate along the length of the seed crystal outer rod 3. The inner diameter of the seed crystal outer rod 3 is larger than its diameter.

[0054] Reference Figure 2-3 To reduce the wobbling of the inner seed rod 2 within the outer seed rod 3, a limiting component 4 is provided between the outer seed rod 3 and the inner seed rod 2. The limiting component 4 is a bearing, which is fixed to the inner wall of the outer seed rod 3. In this embodiment, there are three bearings, which are evenly distributed along the length of the outer seed rod 3. To facilitate the movement of the inner seed rod 2, an inner lifting component 5, which is an inner lifting block, is fixed to the top of the inner seed rod 2. To facilitate the movement of the outer seed rod 3, an outer lifting component 6, which is an outer lifting block, is fixed to the top of the outer wall of the outer seed rod 3.

[0055] Reference Figure 2-3 The bottom end of the seed crystal outer rod 3 has a through hole 31 that matches the seed crystal 1. The seed crystal 1 can reciprocate within the through hole 31, and the diameter of the through hole 31 is smaller than the diameter of the seed crystal inner rod 2. Since the seed crystal inner rod 2 and the seed crystal 1 are fixedly connected, when volatiles adhere to the outer circumferential surface of the seed crystal 1, the seed crystal 1 can be moved within the through hole 31 by moving the seed crystal inner rod 2. When the volatiles come into contact with the bottom end of the seed crystal outer rod 3, they fall off from the bottom end of the seed crystal outer rod 3.

[0056] A method for reducing volatiles generated during gallium oxide crystal growth includes the following steps:

[0057] S1. Install seed crystal 1 at the bottom of seed crystal inner rod 2.

[0058] S2. Heat the gallium oxide raw material to melt it, and obtain molten gallium oxide.

[0059] S3. Pull up the inner seed rod 2, causing it to reciprocate relative to the outer seed rod 3. At the same time, the inner seed rod 2 drives the seed crystal 1 to reciprocate within the through hole 31. When the volatiles on the outer surface of the seed crystal 1 come into contact with the bottom of the outer seed rod 3, the volatiles fall off from the outer surface of the seed crystal 1.

[0060] S4. Move the inner seed rod 2 downwards until its bottom end touches the bottom of the outer seed rod 3. At this time, the inner seed rod 2 and the outer seed rod 3 are relatively fixed, and the seed 1 is located outside the outer seed rod 3.

[0061] S5. Move the outer seed crystal rod 3 downwards, so that the outer seed crystal rod 3 drives the seed crystal 1 and the inner seed crystal rod 2 to move downwards synchronously. Then perform welding, crystal pulling, shoulder formation, equal diameter growth, and demolding.

[0062] In this embodiment, the seed crystal pulling device utilizes the cooperation of the outer seed crystal rod 3 and the inner seed crystal rod 2 to detach the volatiles adhering to the outer peripheral surface of the seed crystal 1 before crystal pulling. Furthermore, the detached volatiles fall onto the mold. Due to the high surface temperature of the mold, the volatiles remelt and evaporate or flow back into the crucible. Since the amount of volatiles at this point is small, they are unlikely to re-adhere to the outer peripheral surface of the seed crystal 1. Then, welding and crystal pulling are performed, effectively reducing the impact of the volatiles adhering to the surface of the seed crystal 1 on the crystallization rate and quality of the gallium oxide crystal.

[0063] Example 2

[0064] A seed crystal pulling device for reducing gallium oxide crystal growth volatiles, which differs from Example 1 in that, referring to... Figure 4 A receiving cavity is formed at the through hole 31 on the bottom wall of the seed crystal outer rod 3. An annular spike 32 is fixedly provided on the circumferential surface of the receiving cavity. The axis of the annular spike 32 coincides with the axis of the seed crystal outer rod 3, and the inner diameter of the annular spike 32 is the same as the inner diameter of the through hole 31. The cross-section of the annular spike 32 is an isosceles triangle, with one end being a fixed end and the other end being a spike end. The fixed end of the annular spike 32 is fixed on the circumferential surface of the receiving cavity, and the spike end is positioned close to the axis of the seed crystal outer rod 3. In this embodiment, there are two spikes, which are evenly distributed along the axis of the seed crystal outer rod 3.

[0065] Example 3

[0066] A seed crystal pulling device for reducing gallium oxide crystal growth volatiles, which differs from Example 1 in that, referring to... Figure 5An annular protrusion 33 is fixedly provided on the bottom wall of the seed crystal outer rod 3 at the through hole 31. The axis of the annular protrusion 33 coincides with the axis of the seed crystal outer rod 3, and the inner diameter of the annular protrusion 33 is the same as the inner diameter of the through hole 31. The cross-section of the annular protrusion 33 is a right-angled triangle, with one end being a fixed end and the other end being a spike end. The fixed end of the annular protrusion 33 is fixed on the bottom wall of the seed crystal outer rod 3, and the spike end is set away from the seed crystal outer rod 3 and is in contact with the outer peripheral surface of the seed crystal 1.

[0067] One end of the volatile material is connected to the outer peripheral surface of the seed crystal 1, while the other end is suspended. If the volatile material tilts towards the outer rod 3 of the seed crystal, the inner rod 2 of the seed crystal is moved, causing the seed crystal 1 to move as well. Then, the spiked end of the annular protrusion 33 contacts the end of the volatile material and applies force to it. The volatile material is forced to detach from the outer peripheral surface of the seed crystal 1, reducing the possibility of the volatile material exploding and scattering in all directions.

[0068] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A seed crystal pulling device for reducing volatiles during gallium oxide crystal growth, characterized in that: The system includes an inner seed crystal rod (2), the bottom end of which is used to fix the seed crystal (1). An outer seed crystal rod (3) is fitted on the outer circumferential surface of the inner seed crystal rod (2). The outer seed crystal rod (3) is a cylindrical shape with an open top, a closed bottom, and a hollow interior. The inner diameter of the outer seed crystal rod (3) is larger than the diameter of the inner seed crystal rod (2). A through hole (31) adapted to the seed crystal (1) is opened at the bottom end of the outer seed crystal rod (3). The inner seed crystal rod (2) moves along the length direction of the outer seed crystal rod (3) and drives the seed crystal (1) to move within the through hole (31). The bottom wall of the seed crystal outer rod (3) is fixed with an annular protrusion (33) with a right-angled triangle cross-section at the through hole (31). The end of the annular protrusion (33) away from the bottom wall of the seed crystal outer rod (3) is a spike end, which is in contact with the outer peripheral surface of the seed crystal (1).

2. The seed crystal pulling device for reducing gallium oxide crystal growth volatiles according to claim 1, characterized in that: A limiting member (4) is provided between the seed crystal outer rod (3) and the seed crystal inner rod (2) to reduce the shaking of the seed crystal inner rod (2).

3. The seed crystal pulling device for reducing gallium oxide crystal growth volatiles according to claim 1, characterized in that: The diameter of the seed crystal inner rod (2) is greater than the diameter of the through hole (31).

4. The seed crystal pulling device for reducing gallium oxide crystal growth volatiles according to claim 1, characterized in that: The seed crystal outer rod (3) is provided with an outer lifting member (6) for moving it, and / or, The seed crystal inner rod (2) is provided with an inner lifting member (5) for moving it.

5. The seed crystal pulling device for reducing gallium oxide crystal growth volatiles according to claim 1, characterized in that: Both the inner rod (2) and the outer rod (3) of the seed crystal are made of high-temperature resistant and oxidation-resistant materials.

6. The seed crystal pulling device for reducing gallium oxide crystal growth volatiles according to claim 5, characterized in that: The high-temperature and oxidation-resistant material is one of iridium, alumina ceramic, or zirconium oxide ceramic.

7. The application of the seed crystal pulling device for reducing gallium oxide crystal growth volatiles as described in any one of claims 1-6, characterized in that: The seed crystal pulling device is used in the growth of gallium oxide crystals by the Czochralski method and the growth of gallium oxide crystals by the guided mode method.

8. A method for reducing gallium oxide crystal growth volatiles, comprising a seed crystal pulling apparatus for reducing crystal growth volatiles as described in any one of claims 1-6.

9. The method for reducing gallium oxide crystal growth volatiles according to claim 8, characterized in that: Includes the following steps: S1. Install the seed crystal (1) at the bottom end of the inner rod (2) of the seed crystal; S2. Heat the gallium oxide raw material to melt it, and obtain molten gallium oxide; S3. Using the inner rod (2) of the seed crystal, the seed crystal (1) is driven to move back and forth in the through hole (31) so that the volatiles adhering to the outer peripheral surface of the seed crystal (1) fall off. S4. Bring the bottom of the inner rod (2) of the seed crystal to contact the bottom of the outer rod (3) of the seed crystal, so that the seed crystal (1) extends out of the outer rod (3); S5. Move the seed crystal outer rod (3) downwards so that the seed crystal outer rod (3) drives the seed crystal (1) and the seed crystal inner rod (2) to move downwards synchronously. Then perform welding, crystal pulling, shoulder formation, equal diameter growth, and demolding.

Images