Semiconductor structure, self-supporting gallium nitride layer and preparation method thereof

Abstract

The present invention relates to a semiconductor structure, a self-supporting gallium nitride layer, and a method for preparing the same. The method comprises: providing a substrate; forming a patterned mask layer on the surface of the substrate, the patterned mask layer having a plurality of openings; forming a gallium nitride seed layer in the openings and on the surface of the patterned mask layer, the gallium nitride seed layer comprising a grain region and an overgrowth region, the dislocation density in the grain region being greater than the dislocation density in the overgrowth region; etching the gallium nitride seed layer to remove the gallium nitride seed layer in the grain region; and forming a thick-film gallium nitride layer, the thick-film gallium nitride layer filling the openings and covering the remaining gallium nitride seed layer. The method for preparing the semiconductor structure provided by the present invention comprises: after removing the gallium nitride seed layer in part or all of the grain region, performing lateral epitaxial growth to form the thick-film gallium nitride layer, thereby improving the crystal quality of the thick-film gallium nitride layer and facilitating the stripping of the thick-film gallium nitride layer.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a semiconductor structure, a self-supporting gallium nitride layer, and a preparation method thereof. Background Art

[0002] Compared with traditional substrate materials, gallium nitride has superior properties such as large bandgap, high breakdown voltage, high thermal conductivity, high electron saturation drift velocity, strong radiation resistance and good chemical stability. It is the material system with the highest theoretical electro-optical and photoelectric conversion efficiency to date.

[0003] Due to the difficulty in preparing GaN single crystal substrates, the current method of heteroepitaxially growing GaN on a foreign substrate such as sapphire, silicon carbide, silicon, or gallium arsenide is generally used to prepare GaN single crystal substrates. The substrate is then exfoliated from the foreign substrate to obtain the GaN single crystal substrate. Among these methods, one technique uses a mask to grow GaN. This involves coating a mask on the foreign substrate. GaN cannot grow epitaxially on this mask, but can only grow within the mask openings. Finally, the mask is closed using lateral epitaxial overgrowth.

[0004] However, this method easily leads to inconsistent dislocations above the opening and above the mask (such as the lateral closure) in the early stages of growth, which in turn affects the improvement of quality and makes it difficult for product performance to meet requirements. Summary of the Invention

[0005] Based on this, it is necessary to provide a semiconductor structure, a self-supporting gallium nitride layer and a preparation method thereof to address the deficiencies in the above-mentioned prior art.

[0006] According to some embodiments, the present application provides a method for preparing a semiconductor structure, comprising:

[0007] providing a substrate;

[0008] forming a patterned mask layer on the surface of the substrate, wherein the patterned mask layer has a plurality of openings;

[0009] forming a gallium nitride seed layer in the opening and on a surface of the patterned mask layer facing away from the substrate, the gallium nitride seed layer comprising a grain region located in the opening and an overgrowth region located on a surface of the patterned mask layer facing away from the substrate, wherein a dislocation density in the grain region is greater than a dislocation density in the overgrowth region;

[0010] Etching the gallium nitride seed layer to completely remove the gallium nitride seed layer located in the grain region, or to make the thickness of the gallium nitride seed layer in the grain region smaller than the thickness of the gallium nitride seed layer in the overgrowth region;

[0011] A thick gallium nitride layer is formed, where the thick gallium nitride layer fills the opening and covers the remaining gallium nitride seed layer.

[0012] In the method for preparing the semiconductor structure provided by the above embodiment, during the process of forming the gallium nitride seed layer on the surface of the patterned mask layer facing away from the substrate and in the opening, initially, gallium nitride grows only in the opening, with a high vertical growth rate, and due to the lattice mismatch between the epitaxially grown gallium nitride and the foreign substrate, a large number of dislocations extend in the vertical direction as the gallium nitride grows, forming a grain region with concentrated dislocations and a high dislocation density. When the thickness of the deposited gallium nitride exceeds the thickness of the patterned mask layer, the gallium nitride grows vertically and gradually becomes thicker, while beginning to grow epitaxially laterally. As the lateral growth rate increases and the lateral epitaxial growth time is sufficient, the gallium nitride grains at adjacent openings begin to contact, connect, and fuse. However, the vertically grown dislocation density cannot be significantly bent and transmitted to the lateral growth region, so the dislocation density of the gallium nitride in the lateral growth region is relatively low, forming an overgrowth region with a lower dislocation density than the grain region. Then, the resulting structure is etched to remove part or all of the gallium nitride seed layer in the grain region, and then the gallium nitride seed layer in the overgrowth region is used as a seed to perform lateral epitaxial growth again to form a thick-film gallium nitride layer. This can avoid the problem of inconsistent dislocations above the opening at the initial stage of gallium nitride growth and above the patterned mask layer (such as the lateral closure), which affects the improvement of quality and makes it difficult for product performance to meet requirements. It improves the crystal quality of the thick-film gallium nitride layer and also helps to peel off the thick-film gallium nitride layer.

[0013] In one embodiment, forming a gallium nitride seed layer in the opening and on a surface of the patterned mask layer facing away from the substrate includes:

[0014] placing the substrate having the patterned mask layer formed thereon in a hydride vapor phase epitaxy device;

[0015] A reaction gas including hydrogen chloride and ammonia is introduced into the hydride vapor phase epitaxy apparatus to form the gallium nitride seed layer in the opening and on the surface of the patterned mask layer facing away from the substrate.

[0016] In the method for preparing the semiconductor structure provided by the above embodiment, gallium nitride generated by the reaction of ammonia with hydrogen chloride and metal gallium can be accurately deposited in the openings of the patterned mask layer, so that the gallium nitride initially grows only in the openings with a high vertical growth rate, and then grows vertically and gradually becomes thicker while starting lateral epitaxial growth.

[0017] In one embodiment, etching the gallium nitride seed layer includes:

[0018] The introduction of ammonia into the hydride vapor phase epitaxy equipment is stopped, and the introduction of hydrogen chloride into the hydride vapor phase epitaxy equipment is continued, and the gallium nitride seed layer is etched using the hydrogen chloride.

[0019] In the method for preparing the semiconductor structure provided by the above embodiment, in-situ etching is performed using the growth gas hydrogen chloride, which does not require furnace operation or the provision of additional gas or pipelines for etching, and is easy to operate.

[0020] In one embodiment, while continuously introducing the hydrogen chloride into the hydride vapor phase epitaxy apparatus, the flow rate of the hydrogen chloride is continuously reduced to a preset flow rate, and the hydrogen chloride etches the gallium nitride seed layer at the preset flow rate.

[0021] In the method for preparing the semiconductor structure provided by the above embodiment, hydrogen chloride has a higher etching rate on the grain region with a higher dislocation density. Therefore, by reducing the flow rate of hydrogen chloride to a preset flow rate, the selective etching of hydrogen chloride can be improved.

[0022] In one embodiment, during the formation of the gallium nitride seed layer, the flow rate of hydrogen chloride is 20 sccm to 1000 sccm; the preset flow rate is 1 sccm to 100 sccm; and the time for the hydrogen chloride to etch the gallium nitride seed layer at the preset flow rate is 10 s to 60 min.

[0023] In one embodiment, the forming of the thick-film gallium nitride layer includes: continuing to introduce the ammonia gas into the hydride vapor phase epitaxy equipment, and continuing to introduce the hydrogen chloride into the hydride epitaxy equipment, so as to form the thick-film gallium nitride layer in the opening and on the surface of the retained gallium nitride seed layer.

[0024] In one embodiment, while introducing the reaction gas into the hydride vapor phase epitaxy apparatus, a carrier gas is also introduced into the hydride vapor phase epitaxy apparatus, and after etching the gallium nitride seed layer and before forming the thick gallium nitride layer, the process further includes:

[0025] Stop introducing the hydrogen chloride gas into the hydride vapor phase epitaxy equipment, and only introduce the carrier gas into the hydride vapor phase epitaxy equipment.

[0026] In one embodiment, the time for introducing the carrier gas into the hydride vapor phase epitaxy apparatus is 1 min to 30 min.

[0027] In the method for preparing the semiconductor structure provided in the above embodiment, the surface of the etched gallium nitride seed layer can be cleaned by maintaining the layer in a carrier gas atmosphere for 1 to 30 minutes. This allows for improved seed quality during subsequent lateral epitaxial growth to form a thick gallium nitride layer using the gallium nitride seed layer in the overgrown region as a seed, thereby achieving a higher-quality thick gallium nitride layer and further facilitating stripping of the thick gallium nitride layer.

[0028] Based on the same inventive concept, the present application also provides a semiconductor structure according to some embodiments, wherein the semiconductor structure is prepared using the method for preparing the semiconductor structure provided by any of the aforementioned embodiments.

[0029] Based on the same inventive concept, the present application also provides, according to some embodiments, a method for preparing a self-supporting gallium nitride layer, comprising:

[0030] Prepare the semiconductor structure by using the method for preparing a semiconductor structure provided by any of the above embodiments;

[0031] The semiconductor structure is subjected to a temperature reduction process so that the thick-film gallium nitride layer is automatically peeled off to obtain a self-supporting gallium nitride layer.

[0032] Based on the same inventive concept, the present application also provides a self-supporting gallium nitride layer according to some embodiments, characterized in that the self-supporting gallium nitride layer is prepared using the preparation method of the self-supporting gallium nitride layer provided in the aforementioned embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 A flowchart of a method for preparing a semiconductor structure provided in one embodiment of the present application.

[0035] Figure 2 A schematic cross-sectional view of the structure obtained in step S20 in the method for preparing a semiconductor structure provided in one embodiment of the present application;

[0036] Figure 3 A flowchart of step S30 in the method for preparing a semiconductor structure provided in one embodiment of the present application;

[0037] Figures 4 to 6A schematic cross-sectional view of the structure obtained in step S30 in the method for preparing a semiconductor structure provided in one embodiment of the present application;

[0038] Figure 7 A schematic cross-sectional view of the structure obtained in step S40 in the method for preparing a semiconductor structure provided in one embodiment of the present application;

[0039] Figures 8 and 9 This is a schematic cross-sectional view of the structure obtained in step S50 in the method for preparing a semiconductor structure provided in one embodiment of the present application; wherein: Figure 9 It is also a schematic cross-sectional structural diagram of a semiconductor structure provided by one of the embodiments of the present application;

[0040] Figure 10 This is a flow chart of a method for preparing a self-supporting gallium nitride layer according to one embodiment of the present application.

[0041] Description of reference numerals:

[0042] 10. Substrate; 20. Patterned mask layer; 30. Opening; 40. GaN seed layer; 401. Grain region; 402. Overgrowth region; 50. Thick-film GaN layer. DETAILED DESCRIPTION

[0043] To facilitate understanding of the present application, a more comprehensive description of the present application will be provided below with reference to the accompanying drawings. The drawings illustrate preferred embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0045] It will be understood that when an element or layer is referred to as being on the surface of another element or layer, it can be directly on the surface of the other element or layer, or intervening elements or layers may be present.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0047] In the case of using “including,” “having,” and “comprising” described herein, another component may be added unless a clear limiting term such as “only,” “consisting of,” etc. is used. Unless mentioned otherwise, a term in the singular form may include a plural form and should not be understood as having one number.

[0048] The traditional method of preparing gallium nitride single crystal substrates easily leads to inconsistent dislocations above the opening and above the mask (such as the lateral closure) in the early stage of growth, which in turn affects the improvement of quality and makes it difficult for product performance to meet requirements.

[0049] Based on the above-mentioned deficiencies in the prior art, the present application provides a method for preparing a semiconductor structure according to some embodiments. Figure 1 As shown, the preparation method may include the following steps:

[0050] S10: providing a substrate;

[0051] S20: forming a patterned mask layer on the surface of the substrate, wherein the patterned mask layer has a plurality of openings;

[0052] S30: forming a gallium nitride seed layer in the opening and on a surface of the patterned mask layer facing away from the substrate, the gallium nitride seed layer comprising a grain region located in the opening and an overgrowth region located on a surface of the patterned mask layer facing away from the substrate, wherein a dislocation density in the grain region is greater than a dislocation density in the overgrowth region;

[0053] S40: etching the gallium nitride seed layer to completely remove the gallium nitride seed layer in the grain region, or to make the thickness of the gallium nitride seed layer in the grain region smaller than the thickness of the gallium nitride seed layer in the overgrowth region;

[0054] S50: forming a thick-film gallium nitride layer, wherein the thick-film gallium nitride layer fills the opening and covers the retained gallium nitride seed layer.

[0055] In the process of forming a gallium nitride seed layer on the surface of the patterned mask layer away from the substrate and in the opening, since gallium nitride only grows at the opening at the beginning, the vertical growth rate is relatively high, and there is a lattice mismatch between the epitaxially grown gallium nitride and the heterogeneous substrate, resulting in a large number of dislocations extending in the vertical direction as the gallium nitride grows, forming a grain area with concentrated dislocations and a high dislocation density; when the thickness of the deposited gallium nitride exceeds the thickness of the patterned mask layer, the gallium nitride grows vertically, slowly becomes thicker, and begins to grow epitaxially laterally. As the lateral growth rate increases, when the lateral epitaxial growth time is sufficient, the gallium nitride grains at adjacent openings begin to contact, connect and fuse, and the vertically grown dislocation density cannot be greatly bent and conducted. To the lateral growth region, the gallium nitride dislocation density in the lateral growth region is low, forming an overgrowth region with a lower dislocation density than the grain region; in the preparation method of the semiconductor structure provided by the above embodiment, after the obtained structure is etched to remove part or all of the gallium nitride seed layer in the grain region, the gallium nitride seed layer in the overgrowth region is used as a seed to perform lateral epitaxial growth again to form a thick-film gallium nitride layer. In this way, the problem of inconsistent dislocations above the opening at the initial stage of gallium nitride growth and above the patterned mask layer (for example, the lateral closed portion) affecting the improvement of quality and making it difficult for product performance to meet the requirements can be avoided, the crystal quality of the thick-film gallium nitride layer is improved, and at the same time, it is also helpful to peel off the thick-film gallium nitride layer.

[0056] For step S10, see Figure 1 S10 steps in Figure 2 , providing a substrate 10.

[0057] The present application does not specifically limit the material of the substrate 10 , and the substrate 10 may include one or more of a silicon substrate, a sapphire substrate, a silicon carbide substrate, a gallium arsenide substrate, an aluminum nitride substrate, or a gallium nitride substrate.

[0058] For step S20, see Figure 1 S20 steps and Figure 2 A patterned mask layer 20 is formed on the surface of the substrate 10 , and the patterned mask layer 20 has a plurality of openings 30 therein.

[0059] The present application does not specifically limit the structure of the patterned mask layer 20. The patterned mask layer 20 may be a single-layer structure, in which case the patterned mask layer 20 may be any one of a metal mask layer, a metal alloy mask layer, a silicon-based oxide mask layer, a silicon-based nitride mask layer, a metal oxide mask layer, or a metal nitride mask layer. The patterned mask layer 20 may also be a multi-layer structure, in which case each layer of the patterned mask layer 20 may be any one of a metal mask layer, a metal alloy mask layer, a silicon-based oxide mask layer, a silicon-based nitride mask layer, a metal oxide mask layer, or a metal nitride mask layer. It should be noted that if the patterned mask layer 20 is a multi-layer structure, the patterns of each layer in the patterned mask layer 20 are generally consistent, that is, the patterned mask layer 20 is produced using a mask with the same pattern. However, depending on the process, the pattern of each layer may be allowed to have a deformation of no more than 20% from the pattern of the mask used to be acceptable.

[0060] Specifically, the patterned mask layer 20 may include a silicon oxide layer (SiO2), a silicon nitride layer (SiN x , x=1, 2, 3 or 4), a titanium oxide layer, a titanium nitride layer, a zirconium oxide layer, a zirconium nitride layer, a chromium oxide layer, a chromium nitride layer or a tungsten nitride layer (WN x , x=1, 2, 3 or 4) and so on; more specifically, the patterned mask layer 20 may include one or more of a silicon carbide layer, a silicon nitride layer, a tungsten nitride layer or a chromium oxide layer and so on.

[0061] The present application does not impose any specific limitation on the thickness of the patterned mask layer 20. In one embodiment, the thickness of the patterned mask layer 20 can be 10 nm to 1000 nm, such as 10 nm, 50 nm, 70 nm, 300 nm, 500 nm, 700 nm, or 1000 nm. Preferably, the thickness of the patterned mask layer 20 is 50 to 700 nm, and more preferably, the thickness of the patterned mask layer 20 is 70 to 300 nm, such as 70 nm, 100 nm, 200 nm, or 300 nm. It will be understood that the above data are merely examples. In actual embodiments, the thickness of the patterned mask layer 20 can be set according to actual needs and is not limited to the above data.

[0062] In other embodiments, the patterned mask layer 20 may also include one or more of a titanium layer, a nickel layer, a tungsten layer, a chromium layer, a cobalt layer or a gold layer, etc.; more specifically, the patterned mask layer 20 includes a titanium layer, a nickel layer, a tungsten layer, a chromium layer, a cobalt layer or a gold layer.

[0063] The present application does not specifically limit the method for forming the patterned mask layer 20. The patterned mask layer 20 may be formed by, but is not limited to, molecular beam epitaxy, evaporation, or sputtering processes.

[0064] Meanwhile, it should be noted that the shape of the opening 30 can be set according to actual needs. The shape of the opening 30 can be a circle, an ellipse, or an equilateral polygon with more than 3 sides.

[0065] In one embodiment, the patterned mask layer 20 may include a plurality of openings 30, and the plurality of openings 30 may be regularly arranged, for example, in a matrix arrangement or a hexagonal array arrangement, etc.; in one embodiment, the diameter of the circumscribed circle of the opening 30 pattern or the smallest circle that can cover the opening 30 is between 1um and 100um, such as 1μm, 20μm, 50μm, 80μm or 100μm, etc.; in another embodiment, the center distances of adjacent openings 30 may be equal, specifically, 1μm to 100μm, more specifically, 1μm, 20μm, 50μm, 80μm or 100μm. m, etc.; in another embodiment, the lateral distance between the centers of adjacent openings 30 may be the same, and the longitudinal distance between the centers of adjacent openings 30 may be the same, but the lateral distance and the longitudinal distance may be different; or, among all the openings 30, the distance from the center of any opening 30 to the center of another adjacent opening 30 does not exceed 5 different data; in other possible embodiments, the shape of the opening 30 may be a strip opening, the width of the strip opening may be 1 μm to 10 μm, specifically 1 μm, 5 μm or 10 μm, and the spacing between adjacent openings 30 may be 1 μm to 10 μm, specifically 1 μm, 5 μm or 10 μm.

[0066] Optionally, in the patterned mask layer 20, the area of ​​the opening 30 may account for 30% to 90% of the total area of ​​the patterned mask layer 20; in one embodiment, the area of ​​the opening 30 accounts for 40% to 80% of the total area of ​​the patterned mask layer 20, specifically, it may be 40%, 50% or 60%, etc.

[0067] For step S30, see Figure 1 S30 steps in Figures 4 to 6 A gallium nitride seed layer 40 is formed in the opening 30 and on the surface of the patterned mask layer 20 facing away from the substrate 10. The gallium nitride seed layer 40 includes a grain region 401 located in the opening 30 and an overgrowth region 402 located on the surface of the patterned mask layer 20 facing away from the substrate 10. The dislocation density in the grain region 401 is greater than the dislocation density in the overgrowth region 402.

[0068] Specifically, in the process of forming the gallium nitride seed layer 40 on the surface of the patterned mask layer 20 facing away from the substrate 10 and in the opening 30, gallium nitride only grows in the opening 30 at the beginning. Figure 4As shown, the vertical growth rate is relatively high, and the lattice mismatch between the epitaxially grown GaN and the foreign substrate 10 causes a large number of dislocations to extend in the vertical direction as the GaN grows, forming a grain region 401 with concentrated dislocations and a high dislocation density. When the thickness of the deposited GaN exceeds the thickness of the patterned mask layer 20, the GaN grows vertically and gradually becomes thicker, and begins to grow epitaxially in the lateral direction. As the lateral growth rate increases and the lateral epitaxial growth time is sufficient, as shown in FIG. Figure 5 As shown, the GaN grains at adjacent openings 30 begin to contact, connect and fuse, while the vertically grown dislocation density cannot be significantly bent and conducted to the lateral growth region. Figure 6 As shown, the dislocation density of GaN in the lateral growth region is low, forming an overgrowth region 402 with a lower dislocation density than the grain region 401 .

[0069] In one embodiment, see Figure 1 S30 steps in Figure 3 , step S30 may include the following steps:

[0070] S301: placing the substrate 10 formed with the patterned mask layer 20 in a hydride vapor phase epitaxy device;

[0071] S302 : introducing reaction gases including hydrogen chloride and ammonia into the hydride vapor phase epitaxy apparatus to form a gallium nitride seed layer 40 in the opening 30 and on the surface of the patterned mask layer 20 facing away from the substrate 10 .

[0072] In the method for preparing the semiconductor structure provided in the above embodiment, the gallium nitride seed layer 40 is prepared by hydride vapor phase epitaxy (HVPE), which not only has a high growth rate but also has low equipment cost. At the same time, the gallium nitride generated by the reaction of ammonia, hydrogen chloride and metallic gallium can be accurately deposited in the opening 30 of the patterned mask layer 20, so that the gallium nitride initially grows only in the opening 30 with a high vertical growth rate, and then begins lateral epitaxial growth while growing vertically and gradually becoming thicker.

[0073] It is understood that the present application does not impose any specific limitation on the growth process conditions of the gallium nitride seed layer 40 .

[0074] In one embodiment, the growth temperature of the gallium nitride seed layer 40 can be set according to actual needs; specifically, the growth temperature of the gallium nitride seed layer 40 is greater than 800°C.

[0075] In one embodiment, the flow rates of hydrogen chloride and ammonia introduced into the hydride vapor phase epitaxy equipment can be set according to actual needs; specifically, the flow rate of ammonia can be 0.5 slm (Standard Liter per Minute) to 30 slm, such as 0.5 slm, 10 slm, 20 slm, or 30 slm; the flow rate of hydrogen chloride can be 20 sccm (Standard Cubic Centimeter per Minute) to 1000 sccm, such as 20 sccm, 100 sccm, 250 sccm, 500 sccm, 750 sccm, or 1000 sccm.

[0076] In one embodiment, the growth time of the gallium nitride seed layer 40 can be set according to actual needs; specifically, the growth time can be 10 minutes to 5 hours, such as 10 minutes, 30 minutes, 1 hour, 3 hours or 5 hours.

[0077] It is understood that the above data are only examples, and in actual embodiments, the growth process conditions of the gallium nitride seed layer 40 are not limited to the above data.

[0078] In one embodiment, the thickness of the gallium nitride seed layer 40 can also be set according to actual needs. Specifically, the thickness of the gallium nitride seed layer 40 can be 1 μm to 250 μm, such as 1 μm, 5 μm, 10 μm, 15 μm, 100 μm, 150 μm, 100 μm, or 250 μm. It will be understood that the above data are only examples. In actual embodiments, the thickness of the gallium nitride seed layer 40 can be set according to actual needs and is not limited to the above data.

[0079] In one embodiment, the hydride vapor phase epitaxy apparatus includes a gallium boat region and a substrate region. The gallium boat region is placed on a gallium boat, and the structure obtained in step S20 is located in the substrate region. The hydrogen chloride in the reaction gas passes through the gallium boat region and reacts with gallium to form gallium chloride while passing through the gallium boat region. The gallium chloride reacts with ammonia in the substrate region to form a gallium nitride seed layer 40.

[0080] In one embodiment, while the reaction gas is introduced into the hydride vapor phase epitaxy apparatus, a carrier gas is also introduced into the hydride vapor phase epitaxy apparatus.

[0081] This application does not specifically limit the type of carrier gas. Specifically, the carrier gas used may include one or more of hydrogen, nitrogen, helium, and argon. It will be appreciated that in actual embodiments, the type of carrier gas may be set according to actual needs. More specifically, in one embodiment, the carrier gas used includes hydrogen.

[0082] For step S40, see Figure 1 S40 steps and Figure 7 , the gallium nitride seed layer 40 is etched to completely remove the gallium nitride seed layer 40 located in the grain region 401 , or to make the thickness of the gallium nitride seed layer 40 located in the grain region 401 smaller than the thickness of the gallium nitride seed layer 40 located in the overgrowth region 402 .

[0083] It is understood that the present application does not limit the specific method of etching the gallium nitride seed layer 40; in one embodiment, the gallium nitride seed layer 40 can be etched using hydrogen chloride by stopping the introduction of ammonia into the hydride vapor phase epitaxy equipment and continuing to introduce hydrogen chloride into the hydride vapor phase epitaxy equipment.

[0084] Hydrogen chloride has a higher etching rate for grain regions with a higher dislocation density. In the semiconductor structure fabrication method provided by the above embodiment, hydrogen chloride is used as a growth gas for in-situ etching, which does not require furnace operation or the provision of additional gases or pipelines for etching, making the operation convenient. By controlling the flow rate of hydrogen chloride and the etching time, the gallium nitride in the grain region of the gallium nitride seed layer 40 is etched faster, and the gallium nitride seed layer 40 in the grain region gradually decreases and becomes concave or completely etched away. The gallium nitride in the overgrowth region is retained due to its better crystal quality and lower etching rate, resulting in a greater thickness of the gallium nitride seed layer 40 in the overgrowth region than in the grain region. In this way, in subsequent processes, the high-quality gallium nitride seed layer 40 in the overgrowth region can be used as a seed for further lateral epitaxial overgrowth of gallium nitride to form a thick gallium nitride layer 50, further improving the crystal quality of the thick gallium nitride layer 50.

[0085] Specifically, after the growth of the gallium nitride seed layer 40 is completed, the introduction of ammonia into the hydride vapor phase epitaxy equipment can be stopped, and the introduction of hydrogen chloride into the hydride vapor phase epitaxy equipment can be continued for a certain time; specifically, the maintenance time can be 10s to 100min, for example, 10s, 1min, 10min, 30min, 50min, 60min, 80min or 100min, etc.

[0086] Optionally, during the process of stopping the introduction of ammonia into the hydride vapor phase epitaxy apparatus and continuing to introduce hydrogen chloride into the hydride vapor phase epitaxy apparatus, the flow rate of the carrier gas introduced into the hydride vapor phase epitaxy apparatus may be the same as or different from that during the formation of the gallium nitride seed layer 40. Specifically, in one embodiment, the flow rate of the carrier gas introduced into the hydride vapor phase epitaxy apparatus is the same as that during the formation of the gallium nitride seed layer 40.

[0087] In one embodiment, while hydrogen chloride is continuously introduced into the hydride vapor phase epitaxy apparatus, the flow rate of hydrogen chloride can be continuously reduced to a preset flow rate, and hydrogen chloride etches the gallium nitride seed layer 40 at the preset flow rate.

[0088] In the method for preparing the semiconductor structure provided by the above embodiment, hydrogen chloride has a higher etching rate on the grain region 401 with a higher dislocation density. Therefore, by reducing the flow rate of hydrogen chloride to a preset flow rate, the selective etching of hydrogen chloride can be improved.

[0089] It is understood that the operation of stopping the flow of ammonia gas into the hydride vapor phase epitaxy apparatus and the operation of reducing the flow of hydrogen chloride can be performed simultaneously; alternatively, the flow of ammonia gas into the hydride vapor phase epitaxy apparatus can be stopped first, maintained for a certain period of time, and then the flow of hydrogen chloride can be reduced. Alternatively, the flow of ammonia gas into the hydride vapor phase epitaxy apparatus can be stopped and maintained for 0 to 30 minutes, and then the flow of hydrogen chloride can be reduced; specifically, the maintenance period can be 5 minutes, 10 minutes, 15 minutes, 20 minutes, or 30 minutes, etc.

[0090] This application does not specifically limit the range of the preset flow rate. Specifically, the preset flow rate can be 1 sccm to 100 sccm, such as 1 sccm, 10 sccm, 50 sccm, 80 sccm, or 100 sccm. It should be understood that the above values ​​are merely examples. In actual embodiments, the preset flow rate can be set according to actual needs and is not limited to the above values.

[0091] The present application does not impose any limitation on the time required to continuously reduce the flow rate of hydrogen chloride to a preset flow rate. Specifically, the time required to reduce the flow rate of hydrogen chloride from the flow rate used to form the gallium nitride seed layer 40 to the preset flow rate is not specifically limited. Specifically, the time required to reduce the flow rate to the preset flow rate can be 10 seconds to 30 minutes, such as 10 seconds, 30 seconds, 1 minute, 5 minutes, 15 minutes, or 30 minutes. It should be understood that the above data are merely examples. In actual embodiments, the time required for hydrogen chloride to etch the gallium nitride seed layer 40 at the preset flow rate can be set according to actual needs and is not limited to the above data. Furthermore, the flow rate of hydrogen chloride can be reduced rapidly in a short period of time or slowly to the preset flow rate.

[0092] In an example, the time for the hydrogen chloride to etch the gallium nitride seed layer 40 at the preset flow rate is 10 seconds to 60 minutes; specifically, it can be 10 seconds, 1 minute, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, or 60 minutes.

[0093] In one embodiment, the temperature in the hydride vapor phase epitaxy equipment in step S40 is lower than the growth temperature of the gallium nitride seed layer 40 in step S30, that is, the etching temperature during the etching of the gallium nitride seed layer 40 in step S40 is lower than the growth temperature of the gallium nitride seed layer 40 and the growth temperature of the subsequently formed thick-film gallium nitride layer; preferably, the etching temperature during the etching of the gallium nitride seed layer 40 in step S40 can be lower than the reaction temperature of hydrogen chloride and gallium to ensure that hydrogen chloride does not react with gallium when passing through the gallium boat area, so that hydrogen chloride can reach the substrate area to etch the gallium nitride seed layer 40, thereby ensuring the etching effect.

[0094] Specifically, in step S40, the temperature in the hydride vapor phase epitaxy equipment can be gradually lowered from the growth temperature of the gallium nitride seed layer 40 to the etching temperature. After reaching the etching temperature, the gallium nitride seed layer 40 is etched. Of course, in other embodiments, the gallium nitride seed layer 40 can also be etched while the temperature is lowered.

[0095] In one embodiment, the preparation method may further include the following steps after etching the gallium nitride seed layer 40 and before forming the thick-film gallium nitride layer 50:

[0096] Stop feeding hydrogen chloride gas into the hydride vapor phase epitaxy equipment, and only feed the carrier gas into the hydride vapor phase epitaxy equipment.

[0097] This application does not impose any specific restrictions on the time for only introducing the carrier gas into the hydride vapor phase epitaxy apparatus. Specifically, the time for only introducing the carrier gas into the hydride vapor phase epitaxy apparatus can be 1 minute to 30 minutes, such as 1 minute, 5 minutes, 15 minutes, or 30 minutes. It will be understood that the above data are merely examples. In actual embodiments, the time for only introducing the carrier gas into the hydride vapor phase epitaxy apparatus can be set according to actual needs and is not limited to the above data.

[0098] Meanwhile, the present application does not impose any specific restrictions on the flow rate of the carrier gas during the process of introducing only the carrier gas into the hydride vapor phase epitaxy apparatus. Specifically, during the process of introducing only the carrier gas into the hydride vapor phase epitaxy apparatus, the flow rate of the carrier gas may be the same as or different from the flow rate of the carrier gas introduced in step S302.

[0099] For step S50, see Figure 1 S50 steps and Figures 8 and 9 , forming a thick-film gallium nitride layer 50 , which fills the opening 30 and covers the retained gallium nitride seed layer 40 .

[0100] Specifically, after the step of etching the gallium nitride seed layer 40 is completed, ammonia gas is first introduced into the hydride vapor phase epitaxy equipment, and then hydrogen chloride gas is introduced. The flow rates of hydrogen chloride and ammonia gas are adjusted to growth flow rates to grow the gallium nitride seed layer 40.

[0101] In another example, step S50 may include: continuing to introduce ammonia gas into the hydride vapor phase epitaxy apparatus, and continuing to introduce hydrogen chloride into the hydride vapor phase epitaxy apparatus, to form a thick GaN layer 50 in the opening 30 and on the surface of the retained GaN seed layer 40 .

[0102] It is understood that the present application does not impose any specific limitation on the growth process conditions of the thick-film gallium nitride layer 50 .

[0103] In one embodiment, the growth temperature of the thick-film GaN layer 50 can be set according to actual needs; specifically, the growth temperature of the thick-film GaN layer 50 is greater than 900° C.

[0104] In one embodiment, the flow rates of hydrogen chloride and ammonia introduced into the hydride vapor phase epitaxy equipment can be set according to actual needs; specifically, the flow rate of ammonia can be 1slm to 30slm, such as 1slm, 10slm, 20slm or 30slm, etc.; the flow rate of hydrogen chloride can be 100sccm to 2000sccm, such as 100sccm, 250sccm, 500sccm, 1000sccm or 2000sccm, etc.

[0105] In one embodiment, the growth time of the thick-film gallium nitride layer 50 can be set according to actual needs; specifically, the growth time can be 5 hours to 20 hours, such as 5 hours, 10 hours, 15 hours or 20 hours.

[0106] It is understood that the above data are only examples, and in actual embodiments, the growth process conditions of the thick-film gallium nitride layer 50 are not limited to the above data.

[0107] It should be noted that if the temperature in the hydride vapor phase epitaxy equipment is lowered to the etching temperature in step S40, the temperature in the hydride vapor phase epitaxy equipment needs to be raised to the temperature required for the growth of the thick film gallium nitride layer 50 in step S50 to ensure the subsequent growth of the gallium nitride layer 50.

[0108] According to some embodiments, the present application also provides a semiconductor structure. Figure 9 The semiconductor structure is prepared by the preparation method of the semiconductor structure provided in any of the aforementioned embodiments. The technical effects that can be achieved by the preparation method of the aforementioned semiconductor structure can also be achieved by the semiconductor structure, which will not be described in detail here.

[0109] According to some embodiments, the present application also provides a method for preparing a self-supporting gallium nitride layer. Figure 10 The method for preparing the self-supporting gallium nitride layer may include the following steps:

[0110] S1: preparing a semiconductor structure by using the method for preparing a semiconductor structure provided by any of the above embodiments;

[0111] S2: Cooling the semiconductor structure so that the thick-film gallium nitride layer 50 is automatically peeled off to obtain a self-supporting gallium nitride layer.

[0112] In the above-mentioned method for preparing a self-supporting gallium nitride layer, the semiconductor structure is prepared using the method for preparing a semiconductor structure provided by any of the aforementioned embodiments. Therefore, the technical effects that can be achieved by the aforementioned method for preparing a semiconductor structure can also be achieved by the method for preparing a self-supporting gallium nitride layer, which will not be described in detail here. Through the cooling treatment, the thick-film gallium nitride layer 50 can be automatically peeled off due to the thermal mismatch between it and the substrate 10.

[0113] According to some embodiments, the present application also provides a self-supporting gallium nitride layer. The self-supporting gallium nitride layer is prepared using the preparation method of the self-supporting gallium nitride layer provided in the aforementioned embodiments. Therefore, the technical effects that can be achieved by the preparation method of the aforementioned self-supporting gallium nitride layer can also be achieved by the self-supporting gallium nitride layer, which will not be described in detail here.

[0114] It should be understood that although Figure 1 、 Figure 3 and Figure 10 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. In addition, Figure 1 、 Figure 3 and Figure 10 At least part of the steps may include multiple steps or multiple stages. These steps or stages are not necessarily performed at the same time, but can be performed at different times. The order of execution of these steps or stages is not necessarily one by one, but can be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.

[0115] The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features of the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0116] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A method for preparing a semiconductor structure, characterized in that: include: providing a substrate; forming a patterned mask layer on the surface of the substrate, wherein the patterned mask layer has a plurality of openings; forming a gallium nitride seed layer in the opening and on a surface of the patterned mask layer facing away from the substrate, the gallium nitride seed layer comprising a grain region located in the opening and an overgrowth region located on a surface of the patterned mask layer facing away from the substrate, wherein a dislocation density in the grain region is greater than a dislocation density in the overgrowth region; Etching the gallium nitride seed layer using hydrogen chloride to completely remove the gallium nitride seed layer in the grain region, or to make the thickness of the gallium nitride seed layer in the grain region thinner than the thickness of the gallium nitride seed layer in the overgrowth region; wherein the etching rate of the hydrogen chloride on the grain region is greater than the etching rate on the overgrowth region; A thick gallium nitride layer is formed by using the gallium nitride seed layer in the overgrowth region as a seed, wherein the thick gallium nitride layer fills the opening and covers the remaining gallium nitride seed layer.

2. The method for preparing a semiconductor structure according to claim 1, wherein: Forming a gallium nitride seed layer in the opening and on a surface of the patterned mask layer facing away from the substrate, comprising: placing the substrate having the patterned mask layer formed thereon in a hydride vapor phase epitaxy device; A reaction gas including hydrogen chloride and ammonia is introduced into the hydride vapor phase epitaxy apparatus to form the gallium nitride seed layer in the opening and on the surface of the patterned mask layer facing away from the substrate.

3. The method for preparing a semiconductor structure according to claim 2, wherein: The etching of the gallium nitride seed layer by using hydrogen chloride includes: The introduction of the ammonia gas into the hydride vapor phase epitaxy equipment is stopped, and the introduction of the hydrogen chloride into the hydride vapor phase epitaxy equipment is continued.

4. The method for preparing a semiconductor structure according to claim 3, wherein: During the process of continuously introducing the hydrogen chloride into the hydride vapor phase epitaxy equipment, the flow rate of the hydrogen chloride is continuously reduced to a preset flow rate, and the hydrogen chloride etches the gallium nitride seed layer at the preset flow rate.

5. The method for preparing a semiconductor structure according to claim 4, wherein: During the formation of the gallium nitride seed layer, the flow rate of the hydrogen chloride is 20 sccm to 1000 sccm; the preset flow rate is 1 sccm to 100 sccm; and the time for the hydrogen chloride to etch the gallium nitride seed layer at the preset flow rate is 10 s to 60 min.

6. The method for preparing a semiconductor structure according to claim 3, wherein: The forming of the thick-film gallium nitride layer using the gallium nitride seed layer in the overgrowth region as a seed includes: continuing to introduce the ammonia gas into the hydride vapor phase epitaxy equipment, and continuing to introduce the hydrogen chloride into the hydride vapor phase epitaxy equipment, so as to form the thick-film gallium nitride layer in the opening and on the surface of the retained gallium nitride seed layer.

7. The method for preparing a semiconductor structure according to claim 3, wherein: While introducing the reaction gas into the hydride vapor phase epitaxy equipment, a carrier gas is also introduced into the hydride vapor phase epitaxy equipment, and after etching the gallium nitride seed layer and before forming the thick-film gallium nitride layer, the method further includes: Stop introducing the hydrogen chloride gas into the hydride vapor phase epitaxy equipment, and only introduce the carrier gas into the hydride vapor phase epitaxy equipment.

8. The method for preparing a semiconductor structure according to claim 7, wherein: The time for introducing the carrier gas into the hydride vapor phase epitaxy equipment is 1 minute to 30 minutes.

9. A semiconductor structure, characterized in that The semiconductor structure is prepared by the method for preparing a semiconductor structure according to any one of claims 1 to 8.

10. A method for preparing a self-supporting gallium nitride layer, characterized in that: include: The semiconductor structure is prepared by the method for preparing a semiconductor structure according to any one of claims 1 to 8; The semiconductor structure is subjected to a temperature reduction process so that the thick-film gallium nitride layer is automatically peeled off to obtain a self-supporting gallium nitride layer.

11. A self-supporting gallium nitride layer, characterized in that: The self-supporting gallium nitride layer is prepared by the method for preparing a self-supporting gallium nitride layer according to claim 10.

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