A rapid preparation method of high-quality gallium oxide epitaxial wafer and high-quality gallium oxide epitaxial wafer

Abstract

The application belongs to the technical field of semiconductors, and particularly relates to a rapid preparation method of high-quality gallium oxide epitaxial wafer and the high-quality gallium oxide epitaxial wafer. The preparation method adopts an HVPE process and comprises a first growth step and a second growth step. The VI / III ratio in the first growth step is controlled to be 2.5-5, and the first growth step lasts for 1-2 hours. The VI / III ratio in the second growth step is controlled to be 5-10, and the second growth step lasts for 2-5 hours. The VI / III ratio in the second growth step is greater than that in the first growth step. The preparation method with two growth steps can not only inhibit crystal defects in the initial stage of epitaxy, reduce structural defects such as twinning and polycrystal in the epitaxial layer, but also promote two-dimensional step flow growth, significantly improve the epitaxial speed, and obtain a high-quality gallium oxide homoepitaxial wafer prepared rapidly. The application provides technical reserves for the preparation of a large-size gallium oxide homoepitaxial wafer, and greatly promotes the landing application of gallium oxide.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, specifically relating to a rapid preparation method for high-quality gallium oxide epitaxial wafers and the high-quality gallium oxide epitaxial wafers themselves. Background Technology

[0002] With the booming development of the semiconductor industry, gallium oxide (GaO) is experiencing increasing market demand in fields such as new energy vehicles and power electronic devices due to its unique advantages in the ultra-wide bandgap semiconductor field. To achieve efficient integration and large-scale production of GaO power devices, the demand for 8-inch and larger GaO epitaxial wafers is becoming increasingly prominent.

[0003] Currently, China has successfully fabricated 8-inch gallium oxide single-crystal substrates, making the development of gallium oxide epitaxial wafers particularly urgent. The mainstream methods for homoepitaxial growth of gallium oxide are metal-organic chemical vapor deposition (MOCVD) and hydride vapor phase epitaxy (HVPE). However, the traditional MOCVD homoepitaxial growth of (100)-plane gallium oxide epitaxial layers has the following main problems: (100)-plane epitaxy is prone to the formation of structural defects such as twins, stacked layers, and polycrystalline composites; the three-dimensional island growth mode results in large surface roughness and poor crystal quality; the flow field structure is complex, the process control is difficult, and the rapid, thick film fabrication is difficult to control. The novel HVPE homoepitaxial process technology has advantages such as simple gas environment, fast growth speed, and low process control difficulty, which is conducive to the rapid and high-quality fabrication of (100)-plane gallium oxide epitaxial layers.

[0004] However, when using the current HVPE homoepitaxial process to prepare thick gallium oxide epitaxial wafers, it is not only necessary to repeat the epitaxial growth steps multiple times, but it is also difficult to obtain high-quality thick gallium oxide epitaxial films with smooth surfaces and no polycrystalline defects. Furthermore, the epitaxial speed is slow and the production efficiency needs to be improved. Summary of the Invention

[0005] In view of this, the present invention provides a rapid preparation method for high-quality gallium oxide epitaxial wafers and a high-quality gallium oxide epitaxial wafer. The preparation method adopts a two-step growth approach to suppress early epitaxial defects and promote two-dimensional step flow growth, thereby rapidly obtaining a thicker, high-quality gallium oxide epitaxial layer.

[0006] In a first aspect, the present invention provides a rapid preparation method for high-quality gallium oxide epitaxial wafers, employing an HVPE process, comprising a first growth step and a second growth step; wherein, in the first growth step, the VI / III ratio is controlled to be 2.5~5, and the growth is sustained for 1~2 hours; in the second growth step, the VI / III ratio is controlled to be 5~10, and the growth is sustained for 2~5 hours; and the VI / III ratio of the second growth step is controlled to be greater than the VI / III ratio of the first growth step.

[0007] In one possible implementation, the first growth step specifically comprises:

[0008] A (100)-plane gallium oxide substrate is placed in an epitaxial growth system, a carrier gas is introduced, the pressure in the epitaxial growth system is set to a first preset pressure, the temperature is raised to a first preset temperature, and hydrogen is introduced to pre-treat the gallium oxide substrate.

[0009] Remove hydrogen from the epitaxial growth system, reintroduce carrier gas, set the pressure in the epitaxial growth system to the second preset pressure, and raise the source region temperature to the second preset temperature and the growth region temperature to the third preset temperature.

[0010] Hydrogen chloride, oxygen and hydrogen are simultaneously introduced into the epitaxial growth system, and the VI / III ratio is controlled at 3~4.5, and growth is continued for 1~2 hours;

[0011] The second growth step is as follows:

[0012] After the first growth step is completed, hydrogen chloride, oxygen and hydrogen are continuously introduced simultaneously, and the VI / III ratio is controlled at 6~9. The growth continues for 2~5 hours, and then cooled to room temperature to obtain a high-quality gallium oxide epitaxial wafer.

[0013] In one possible implementation, the (100)-plane gallium oxide substrate has an offset angle ranging from 2 to 6°;

[0014] The carrier gas is nitrogen or argon, and the flow rate of the carrier gas is 6000~8000 sccm.

[0015] In one possible implementation, the first preset pressure is 150~250 mbar and the first preset temperature is 500~600℃.

[0016] In one possible implementation, the pretreatment of the gallium oxide substrate by introducing hydrogen gas specifically involves introducing hydrogen gas at a flow rate of 20-50 sccm and treating the gallium oxide substrate for 10-15 minutes.

[0017] In one possible implementation, the removal of hydrogen from the epitaxial growth system specifically involves: after the gallium oxide substrate has been pretreated with hydrogen, the hydrogen supply is stopped, and the pressure in the reaction chamber is set to 0 mbar until the hydrogen in the reaction chamber is completely removed.

[0018] In one possible implementation, the second preset pressure is 150~250 mbar, the second preset temperature is 850~900℃, and the third preset temperature is 1000~1050℃.

[0019] In one possible implementation, during the first growth step, the flow rate of hydrogen chloride is 20-40 sccm, the flow rate of oxygen is 90-120 sccm, and the flow rate of hydrogen is 20-40 sccm.

[0020] In one possible implementation, during the second growth step, the flow rate of hydrogen chloride is 20-40 sccm, the flow rate of oxygen is 180-220 sccm, and the flow rate of hydrogen is 20-40 sccm.

[0021] In a second aspect, the present invention provides a high-quality gallium oxide epitaxial wafer, prepared according to the preparation method described in the first aspect or any possible implementation thereof.

[0022] Compared with the (100) plane gallium oxide epitaxial layer prepared by the conventional HVPE method, the two-step growth method provided by this invention can not only suppress crystal defects in the early stage of epitaxy and reduce structural defects such as twins and polycrystalline structures in the epitaxial layer, but also promote two-dimensional step flow growth, significantly improve the epitaxial speed, and thus obtain a high-quality (100) plane gallium oxide homoepitaxial wafer with a larger thickness that can be prepared quickly. This provides an innovative technical reserve for the preparation of large-size (100) plane gallium oxide homoepitaxial wafers and also plays a great role in promoting the practical application of gallium oxide. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a surface morphology diagram of the epitaxial layer obtained in the first growth step of an embodiment of the present invention;

[0025] Figure 2 This is a surface morphology diagram of the epitaxial layer obtained in the second growth step of an embodiment of the present invention;

[0026] Figure 3 This is a surface morphology diagram of the epitaxial layer obtained in Comparative Example 1 of the present invention;

[0027] Figure 4 This is a surface morphology diagram of the epitaxial layer obtained in Comparative Example 2 of the present invention;

[0028] Figure 5 This is a surface morphology diagram of the epitaxial layer obtained in the first growth step of Comparative Example 3 of the present invention;

[0029] Figure 6This is a surface morphology diagram of the epitaxial layer obtained in the second growth step in Comparative Example 3 of the present invention;

[0030] Figure 7 This is a surface morphology diagram of the epitaxial layer obtained in Comparative Example 4 of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0032] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the meaning consistent with their meaning in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined.

[0033] Currently, although the HVPE homoepitaxial process can enable homoepitaxial growth of gallium oxide on the (100) plane, this process cannot quickly obtain high-quality thick epitaxial films, and the surface of the epitaxial layer is prone to structural defects such as twins, stacked layers, and polycrystalline composites.

[0034] In view of this, the present invention provides a rapid preparation method for high-quality gallium oxide epitaxial wafers and a high-quality gallium oxide epitaxial wafer. The preparation method innovatively adopts a two-step growth to suppress crystal defects in the early stage of epitaxy, reduce structural defects such as twinning and polycrystalline in the epitaxial layer, and promote two-dimensional step flow growth, thereby obtaining a rapid and high-quality (100) plane gallium oxide homogeneous epitaxial wafer, providing material support for the development of gallium oxide power devices.

[0035] In this embodiment, the HVPE process is used, including a first growth step and a second growth step; wherein, the first growth step controls the VI / III ratio to be 2.5~5 and grows continuously for 1~2 hours, the second growth step controls the VI / III ratio to be 5~10 and grows continuously for 2~5 hours, and the VI / III ratio of the second growth step is controlled to be greater than the VI / III ratio of the first growth step.

[0036] In the first growth step, a relatively low oxygen to hydrogen chloride flow rate ratio is used, resulting in a relatively high hydrogen chloride flow rate and a relatively low oxygen flow rate. This increases the amount of gallium chloride produced by the reaction of hydrogen chloride with gallium, leading to an increase in the amount of gallium chloride reaching the surface of the atomic steps on the substrate. The gallium chloride adsorbed on the surface migrates to the atomic steps, forming more nucleation sites, thus promoting the formation of the gallium-oxygen atomic layer. Simultaneously, the diffusion of gallium atoms facilitates two-dimensional epitaxial growth, reducing three-dimensional island growth and effectively suppressing crystal defects in the early stages of epitaxy, reducing the formation of structural defects such as twins, stacked layers, and polycrystalline composites in the epitaxial layer. In the second growth step, a higher oxygen to hydrogen chloride flow rate ratio is used, ensuring a relatively stable and sufficient gallium chloride concentration in the reaction system. Increasing the oxygen flow rate promotes the forward reaction of gallium chloride with oxygen to form gallium oxide, thereby rapidly increasing the growth rate.

[0037] In one possible implementation, the first growth step specifically involves:

[0038] A (100)-plane gallium oxide substrate is placed in an epitaxial growth system, a carrier gas is introduced, the pressure in the epitaxial growth system is set to a first preset pressure, the temperature is raised to a first preset temperature, and hydrogen is introduced to pre-treat the gallium oxide substrate.

[0039] Remove hydrogen from the epitaxial growth system, reintroduce carrier gas, set the pressure in the epitaxial growth system to the second preset pressure, and raise the source region temperature to the second preset temperature and the growth region temperature to the third preset temperature.

[0040] Hydrogen chloride, oxygen and hydrogen are simultaneously introduced into the epitaxial growth system, and the VI / III ratio is controlled at 3~4.5, and growth is continued for 1~2 hours;

[0041] The second growth step is as follows:

[0042] After the first growth step is completed, hydrogen chloride, oxygen and hydrogen are continuously introduced simultaneously, and the VI / III ratio is controlled at 6~9. The growth continues for 2~5 hours, and then cooled to room temperature to obtain a high-quality gallium oxide epitaxial wafer.

[0043] In the two growth steps, the growth rate of the epitaxial layer is controlled by adjusting VI / III to ensure the quality of the epitaxial wafer.

[0044] In the first growth step, a smaller VI / III ratio is used to increase the amount of gallium chloride generated, which increases the amount of gallium chloride reaching the surface of the atomic steps on the substrate. The gallium chloride adsorbed on the surface migrates to the atomic steps to form more nucleation sites, thereby promoting the formation of gallium-oxygen atomic layers. At the same time, the diffusion of gallium atoms is conducive to epitaxial growth in a two-dimensional growth mode, reducing three-dimensional island growth, thus effectively suppressing crystal defects in the early stage of epitaxy and reducing the generation of structural defects such as epitaxial layer twins, stacked layers, and polycrystalline composites.

[0045] In the second growth step, a larger VI / III ratio is used. At this time, the concentration of gallium chloride in the reaction system is relatively stable and sufficient. Increasing the oxygen flow rate can promote the forward reaction of gallium chloride and oxygen to generate gallium oxide, thereby rapidly increasing the growth rate.

[0046] Preferably, in the first growth step, the VI / III ratio is controlled to be 3.5 to 4.5; in the second growth step, the VI / III ratio is controlled to be 6 to 8.

[0047] More preferably, in the first growth step, the VI / III ratio is controlled to be 4; and in the second growth step, the VI / III ratio is controlled to be 7.

[0048] Hydrogen has a positive impact on the kinetic conditions of the substrate surface, which can promote the step flow growth of epitaxial layered films, facilitate the formation of continuous stripe morphology, reduce epitaxial defect density, and further improve the quality of epitaxial films.

[0049] In one possible implementation, the (100)-plane gallium oxide substrate has an offset angle ranging from 2 to 6°; the carrier gas is nitrogen or argon, and the flow rate of the carrier gas is 6000 to 8000 sccm.

[0050] The deflection angle of a gallium oxide substrate refers to the angular deviation of the wafer surface from the ideal crystal plane. In practical applications, depending on the different deflection angles of the substrate, the epitaxial structure defects can be suppressed by adjusting the flow ratio of hydrogen chloride, oxygen and hydrogen, and the growth mode of the step flow can be controlled, thereby quickly obtaining high-quality (100)-plane gallium oxide homoepitaxial wafers.

[0051] Carrier gas is an auxiliary gas used in epitaxial growth to transport reactive gases to the substrate in the reaction chamber and help maintain the stability of the reaction environment.

[0052] In one possible implementation, the first preset pressure is 150~250 mbar and the first preset temperature is 500~600℃.

[0053] The carrier gas flow rate, first preset pressure, and first preset temperature selected in this embodiment are determined based on the reaction characteristics of gallium oxide pretreatment. The specific reaction pressure and temperature can be selected within this range according to actual needs.

[0054] In one possible implementation, the pretreatment of the gallium oxide substrate by introducing hydrogen gas specifically involves introducing hydrogen gas at a flow rate of 20-50 sccm and treating the gallium oxide substrate for 10-15 minutes.

[0055] Pretreatment of gallium oxide substrates with hydrogen gas within a certain flow rate range can remove the sub-damaged layer on the surface of the gallium oxide substrate. The aforementioned hydrogen flow rate range and treatment time can achieve good pretreatment results. As the flow rate of hydrogen gas increases, the reaction rate between hydrogen gas and the surface of gallium oxide substrates also increases, so the pretreatment time can be appropriately shortened within the aforementioned range.

[0056] In one possible implementation, removing hydrogen from the epitaxial growth system specifically involves: after pretreating the gallium oxide substrate with hydrogen, stopping the hydrogen supply, setting the pressure in the step reaction chamber to 0 mbar, and continuing this process until the hydrogen in the step reaction chamber is completely removed.

[0057] Removing hydrogen from the epitaxial growth system after pretreatment ensures the epitaxial growth effect and avoids the impact of large flow rates of hydrogen during pretreatment on epitaxial growth.

[0058] In one possible implementation, the second preset pressure is 150~250 mbar, the second preset temperature is 850~900℃, and the third preset temperature is 1000~1050℃.

[0059] During epitaxial growth, the growth temperature, internal pressure of the growth system, and flow rate of the reactant gas all affect the growth effect. Excessively high growth temperatures may lead to material decomposition, while excessively low temperatures will affect the quality of the epitaxial wafer. High internal pressure of the growth system is beneficial for increasing the growth rate, but may increase the defect density in the film; low internal pressure, while improving the quality of the epitaxial wafer, will slow down the growth rate. The second preset pressure, second preset temperature, and third preset temperature selected in this embodiment can ensure good epitaxial growth results.

[0060] In one possible implementation, during the first growth step, the flow rate of hydrogen chloride is 20-40 sccm, the flow rate of oxygen is 90-120 sccm, and the flow rate of hydrogen is 20-40 sccm.

[0061] In one possible implementation, during the second growth step, the flow rate of hydrogen chloride is 20-40 sccm, the flow rate of oxygen is 180-220 sccm, and the flow rate of hydrogen is 20-40 sccm.

[0062] Preferably, in the first growth step, the flow rate of hydrogen chloride is 23-30 sccm and the flow rate of oxygen is 100 sccm; in the second growth step, the flow rate of hydrogen chloride is 23-30 sccm and the flow rate of oxygen is 200 sccm.

[0063] This embodiment uses a relatively large flow rate of hydrogen gas during the epitaxial growth process to suppress defects on the surface of the epitaxial layer, thereby obtaining a high-quality gallium oxide epitaxial wafer with greater thickness, a smooth surface, and no polycrystalline defects.

[0064] In one specific embodiment, the rapid fabrication method for high-quality gallium oxide epitaxial wafers provided by the present invention may include a first growth step and a second growth step, wherein the first growth step includes:

[0065] Step 1: Place the gallium oxide substrate with the (100) plane offset by 4°±0.5° in the reaction chamber of the epitaxial growth system. Use nitrogen gas at 6000~8000 sccm as the carrier gas. Set the pressure in the epitaxial growth system to 150~250 mbar. Raise the temperature in the reaction chamber of the epitaxial growth system to 500~600℃. After the temperature stabilizes, introduce hydrogen gas at 20~50 sccm to pretreat the substrate for 10~15 min.

[0066] Step 2: Stop the hydrogen supply and set the pressure in the epitaxial growth system to 0 mbar until the hydrogen is completely removed. Then, reset the pressure in the reaction chamber of the epitaxial growth system to 150-250 mbar and raise the source region temperature to 850-900℃ and the growth region temperature to 1000-1050℃.

[0067] Step 3: After the temperature stabilizes, hydrogen chloride, oxygen, and hydrogen are simultaneously introduced into the epitaxial growth system as reaction source gases. The flow rate of hydrogen chloride is 23-30 sccm, the flow rate of oxygen is 100 sccm, and the flow rate of hydrogen is 20-40 sccm. Growth continues for 1-2 hours to obtain an epitaxial film with a thickness of 2 μm and the morphology is as follows. Figure 1 As shown. By Figure 1 It can be seen that the surface of the epitaxial wafer is flat and has a striped morphology, without structural defects such as twins or polycrystalline structures. This indicates that the preparation method effectively suppresses crystal defects in the early stage of epitaxy, and also shows that the hydrogen flow rate selected in this invention can promote the epitaxial wafer surface to grow to be flatter.

[0068] The second growth step includes:

[0069] Step 4: After the first growth step is completed, continue to simultaneously introduce hydrogen chloride, oxygen and hydrogen. Set the flow rate of hydrogen chloride to 23~30 sccm, the flow rate of oxygen to 200 sccm, and the flow rate of hydrogen to 20~40 sccm, and continue growth for 2~5 hours. After the epitaxial growth is completed, set the temperature of the epitaxial growth system to 23℃ and wait for it to cool down naturally to room temperature to obtain a high-quality gallium oxide epitaxial wafer.

[0070] Tests showed that the thickness of the obtained epitaxial wafer was 7 μm, the epitaxial speed was 3.5 μm / h, and the morphology was as follows. Figure 2As shown, the epitaxial stripes on the surface of the epitaxial wafer are continuous and there are basically no structural defects such as twins or polycrystalline structures. This indicates that the epitaxy maintains the step flow growth mode and also shows that the preparation method effectively suppresses the generation of island-shaped polycrystalline defects, thus obtaining high-quality epitaxial wafers in a shorter time.

[0071] This invention also provides a high-quality gallium oxide epitaxial wafer, prepared according to the preparation method of the first aspect or any possible implementation thereof.

[0072] Comparative Example 1

[0073] This comparative example provides a method for preparing gallium oxide epitaxial wafers, the method of which is as follows:

[0074] Step 1: Place the gallium oxide substrate with a (100) plane offset of 4°±0.5° in the reaction chamber of the epitaxial growth system, use 6000 sccm of nitrogen as the carrier gas, set the pressure in the epitaxial growth system to 150 mbar, raise the temperature in the reaction chamber of the epitaxial growth system to 600℃, and after the temperature stabilizes, introduce 20 sccm of hydrogen to pretreat the substrate for 15 min.

[0075] Step 2: Stop the hydrogen supply, set the pressure in the epitaxial growth system to 0 mbar until the hydrogen is completely removed, reset the pressure in the reaction chamber of the epitaxial growth system to 150 mbar, and raise the source region temperature of the epitaxial growth system to 900℃ and the growth region temperature to 1000℃.

[0076] Step 3: After the temperature stabilizes, hydrogen chloride, oxygen, and hydrogen are simultaneously introduced into the epitaxial growth system as reaction source gases. The flow rate of hydrogen chloride is 20 sccm, the flow rate of oxygen is 100 sccm (oxygen to hydrogen chloride flow rate ratio is 5), and the flow rate of hydrogen is 20 sccm. Growth continues for 4 hours. After epitaxial growth is complete, the temperature of the epitaxial growth system is set to 23℃ and allowed to cool naturally to room temperature, resulting in a 4 μm thick epitaxial film. The epitaxial rate is 1 μm / h. The morphology of the epitaxial layer is as follows. Figure 3 As shown, spindle-shaped defects appear in the epitaxial layer.

[0077] The difference between this comparative example and the embodiment is that the epitaxial growth process did not involve a two-step growth process, i.e., the flow ratio of oxygen and hydrogen chloride was not changed, but the ratio in step three of the first growth step was directly used and the growth continued for 4 hours.

[0078] Comparing Comparative Example 1 and the Example, it can be seen that in the second growth step, the Example increases the epitaxial growth rate from 1 μm / h in Comparative Example 1 to 3.5 μm / h by increasing the oxygen / hydrogen chloride ratio, resulting in a 3.5-fold increase in epitaxial layer growth rate and significantly improving the growth speed of the epitaxial wafer. Comparative Example 1 did not change the oxygen / hydrogen chloride ratio, and spindle-shaped structural defects appeared on the epitaxial layer surface. In contrast, the epitaxial layer surface of the Example is smooth and free of spindle-shaped structural defects. This demonstrates that the present invention, by changing the stepwise growth method of the oxygen / hydrogen chloride ratio, effectively suppresses epitaxial defects while achieving rapid epitaxial layer growth, promotes step flow growth, and obtains a continuous striped morphology. Therefore, the preparation method of the present invention is beneficial for achieving rapid and high-quality thick film preparation of (100)-plane gallium oxide epitaxial layers to meet the requirements of power devices for thick gallium oxide films.

[0079] Comparative Example 2

[0080] This comparative example provides a method for preparing a gallium oxide epitaxial wafer, the method comprising a first growth step and a second growth step, wherein the first growth step includes the following steps:

[0081] Step 1 is the same as Step 1 in the embodiment, and will not be repeated here.

[0082] Step two is the same as step two in the embodiment, and will not be repeated.

[0083] Step 3: After the temperature stabilizes, hydrogen chloride, oxygen and hydrogen are simultaneously introduced into the epitaxial growth system as reaction source gases. The flow rate of hydrogen chloride is 20 sccm, the flow rate of oxygen is 200 sccm (the flow rate ratio of oxygen to hydrogen chloride is 10), and the flow rate of hydrogen is 20 sccm. The growth continues for 2 hours.

[0084] The second growth step includes the following steps:

[0085] Step 4: After the first growth step, hydrogen chloride, oxygen, and hydrogen are simultaneously introduced. The flow rate of hydrogen chloride is set to 20 sccm, the flow rate of oxygen to 100 sccm (oxygen to hydrogen chloride flow rate ratio of 5), and the flow rate of hydrogen to 20 sccm. Growth continues for 2 hours. After epitaxial growth is complete, the epitaxial growth system temperature is set to 23℃ and allowed to cool naturally to room temperature, resulting in an epitaxial film with a total epitaxial layer thickness of 14 μm and an epitaxial rate of 3.3 μm / h. The epitaxial layer morphology is as follows. Figure 4 As shown, the epitaxial layer is of very poor quality and has a large number of polycrystalline defects (black spot areas) on its surface.

[0086] The difference between this comparative example and the embodiment is that, in the epitaxial growth process, a relatively large proportion of oxygen / hydrogen chloride flow rate is used in the first growth step, while a relatively small proportion of oxygen / hydrogen chloride flow rate is used in the second growth step.

[0087] Comparing Comparative Example 2 and the Example, it can be seen that the preparation method provided in the Example has a faster epitaxial growth rate, indicating that high-speed epitaxial growth has been achieved; moreover, the epitaxial layer obtained in the Example has a smooth surface, no polycrystalline defects, and exhibits step-flow growth. In contrast, the preparation method in Comparative Example 1 initially uses a large proportion of oxygen / hydrogen chloride flow rate followed by a small proportion. Due to the excessively rapid initial growth rate, crystal defects in the early stage of epitaxy were not effectively suppressed, resulting in the gradual exposure of defects during subsequent epitaxial growth, ultimately leading to polycrystalline defects.

[0088] Comparative Example 3

[0089] This comparative example provides a method for preparing a gallium oxide epitaxial wafer, the method comprising a first growth step and a second growth step, wherein the first growth step includes the following steps:

[0090] Step 1 is the same as Step 1 in the embodiment, and will not be repeated here.

[0091] Step two is the same as step two in the embodiment, and will not be repeated.

[0092] Step 3: After the temperature stabilizes, hydrogen chloride, oxygen, and hydrogen are simultaneously introduced into the epitaxial growth system as reaction source gases. The flow rate of hydrogen chloride is 20 sccm, the flow rate of oxygen is 100 sccm (the flow rate ratio of oxygen to hydrogen chloride is 5), and the flow rate of hydrogen is 1 sccm. Growth is continued for 30 minutes to obtain an epitaxial film with a thickness of 500 nm, and the morphology is as follows. Figure 5 As shown, the surface of most areas of the epitaxial layer is flat with almost no polycrystalline defects, indicating that the presence of low-flow hydrogen has a positive impact on the kinetic conditions of the substrate surface and promotes the growth of the layered film.

[0093] The second growth step includes the following steps:

[0094] Step 4: After the first growth step, hydrogen chloride, oxygen, and hydrogen are continuously introduced simultaneously. The flow rate of hydrogen chloride is set to 20 sccm, the flow rate of oxygen to 200 sccm (oxygen to hydrogen chloride flow rate ratio of 10), and the flow rate of hydrogen to 1 sccm. Growth continues for 4 hours. After epitaxial growth is complete, the epitaxial growth system temperature is set to 23℃ and allowed to cool naturally to room temperature, resulting in a 4 μm thick gallium oxide epitaxial wafer with the following morphology. Figure 6 As shown, some polycrystalline defects (black spot areas) appear on the surface of the epitaxial layer, indicating that the low-flow hydrogen preparation method in Comparative Example 3 cannot effectively suppress defects when preparing thick films.

[0095] The difference between this comparative example and the embodiment is that the flow rate of hydrogen used in the first growth step and the second growth step is 1 sccm, and the growth time is different.

[0096] Comparing Comparative Example 3 and the Examples, it can be seen that the preparation method provided in the Examples can be used to prepare thicker epitaxial films, while the method in Comparative Example 3 is not suitable for thick film preparation and cannot obtain high-quality gallium oxide thick epitaxial films with smooth surfaces and no polycrystalline defects.

[0097] Comparative Example 4

[0098] This comparative example provides a method for preparing a gallium oxide epitaxial wafer, the method comprising a first growth step and a second growth step, wherein the first growth step includes the following steps:

[0099] Step 1 is the same as Step 1 in the embodiment, and will not be repeated here.

[0100] Step two is the same as step two in the embodiment, and will not be repeated.

[0101] Step 3: After the temperature stabilizes, hydrogen chloride, oxygen and hydrogen are simultaneously introduced into the epitaxial growth system as reaction source gases. The flow rate of hydrogen chloride is 20 sccm, the flow rate of oxygen is 100 sccm (the flow rate ratio of oxygen to hydrogen chloride is 5), and the flow rate of hydrogen is 200 sccm. The growth continues for 2 hours.

[0102] The second growth step includes the following steps:

[0103] Step 4: After the first growth step, hydrogen chloride, oxygen, and hydrogen are simultaneously introduced. The flow rate of hydrogen chloride is set to 20 sccm, the flow rate of oxygen to 200 sccm (oxygen to hydrogen chloride flow rate ratio of 10), and the flow rate of hydrogen to 200 sccm, and growth continues for 2 hours. After epitaxial growth is complete, the epitaxial growth system temperature is set to 23℃ and allowed to cool naturally to room temperature, resulting in a 7 μm thick gallium oxide epitaxial wafer with the following morphology. Figure 7 As shown, there are a large number of polycrystalline defects (black spot areas) on the surface of the epitaxial layer, indicating that the hydrogen flow rate will have a relatively severe etching effect on the substrate surface, damaging the substrate surface and generating defects.

[0104] The difference between this comparative example and the embodiment is that the flow rate of hydrogen used in both the first and second growth steps is 200 sccm.

[0105] Comparing Comparative Example 4 and the Examples, it can be seen that the preparation method provided in the Examples, by controlling the gas parameters, ensures that under the appropriate hydrogen flow rate, it can promote a smoother epitaxial surface growth while avoiding severe etching of the surface, thereby ensuring step flow growth, suppressing the generation of polycrystalline defects, and finally obtaining a high-quality epitaxial wafer.

[0106] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A rapid preparation method for high-quality gallium oxide epitaxial wafers, characterized in that, The HVPE process includes a first growth step and a second growth step. In the first growth step, the VI / III ratio is controlled to be 2.5 to 5 and the growth is continued for 1 to 2 hours. In the second growth step, the VI / III ratio is controlled to be 5 to 10 and the growth is continued for 2 to 5 hours. Furthermore, the VI / III ratio of the second growth step is controlled to be greater than that of the first growth step. In both the first and second growth steps, the flow rate of hydrogen is 20~40 sccm.

2. The rapid fabrication method for high-quality gallium oxide epitaxial wafers as described in claim 1, characterized in that, The first growth step is specifically as follows: A (100)-plane gallium oxide substrate is placed in an epitaxial growth system, a carrier gas is introduced, the pressure in the epitaxial growth system is set to a first preset pressure, the temperature is raised to a first preset temperature, and hydrogen is introduced to pre-treat the gallium oxide substrate. Remove hydrogen from the epitaxial growth system, reintroduce carrier gas, set the pressure in the epitaxial growth system to the second preset pressure, and raise the source region temperature to the second preset temperature and the growth region temperature to the third preset temperature. Hydrogen chloride, oxygen and hydrogen are simultaneously introduced into the epitaxial growth system, and the VI / III ratio is controlled at 3~4.5, and growth is continued for 1~2 hours; The second growth step is as follows: After the first growth step is completed, hydrogen chloride, oxygen and hydrogen are continuously introduced simultaneously, and the VI / III ratio is controlled at 6~9. The growth continues for 2~5 hours, and then cooled to room temperature to obtain a high-quality gallium oxide epitaxial wafer.

3. The rapid fabrication method for high-quality gallium oxide epitaxial wafers as described in claim 2, characterized in that, The (100) plane gallium oxide substrate has an offset angle ranging from 2 to 6°; The carrier gas is nitrogen or argon, and the flow rate of the carrier gas is 6000~8000 sccm.

4. The rapid fabrication method for high-quality gallium oxide epitaxial wafers as described in claim 2, characterized in that, The first preset pressure is 150~250 mbar, and the first preset temperature is 500~600℃.

5. The rapid fabrication method for high-quality gallium oxide epitaxial wafers as described in claim 4, characterized in that, The pretreatment of the gallium oxide substrate by introducing hydrogen gas specifically involves introducing hydrogen gas at a flow rate of 20-50 sccm and treating the gallium oxide substrate for 10-15 minutes.

6. The rapid fabrication method for high-quality gallium oxide epitaxial wafers as described in claim 2, characterized in that, The removal of hydrogen from the epitaxial growth system specifically involves: after the gallium oxide substrate has been pretreated with hydrogen, the hydrogen supply is stopped, and the pressure in the reaction chamber is set to 0 mbar until the hydrogen in the reaction chamber is completely removed.

7. The rapid fabrication method for high-quality gallium oxide epitaxial wafers as described in claim 2, characterized in that, The second preset pressure is 150~250 mbar, the second preset temperature is 850~900℃, and the third preset temperature is 1000~1050℃.

8. The rapid fabrication method for high-quality gallium oxide epitaxial wafers as described in claim 2, characterized in that, In the first growth step, the flow rate of hydrogen chloride is 20-40 sccm, the flow rate of oxygen is 90-120 sccm, and the flow rate of hydrogen is 20-40 sccm.

9. The rapid fabrication method for high-quality gallium oxide epitaxial wafers as described in claim 2 or 7, characterized in that, In the second growth step, the flow rate of hydrogen chloride is 20-40 sccm, the flow rate of oxygen is 180-220 sccm, and the flow rate of hydrogen is 20-40 sccm.

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