Semiconductor structure, self-supporting gallium nitride layer and method for preparing same

Abstract

The present application relates to a semiconductor structure, a self-supporting gallium nitride layer and a method for preparing the same. The method for preparing the semiconductor structure includes providing a substrate, forming a patterned mask layer on the surface of the substrate, and the patterned mask layer has openings; placing the substrate in a hydride vapor epitaxy device; forming a gallium nitride seed layer in the openings and on the surface of the patterned mask layer facing away from the substrate, the gallium nitride seed layer includes a first region located in the openings and a second region located on the surface of the patterned mask layer, and the dislocation density in the first region is greater than that in the second region; etching the gallium nitride seed layer to remove all or part of the gallium nitride seed layer located in the first region; introducing a doping gas into the hydride vapor epitaxy device to form a doped thick film gallium nitride layer. The method for preparing the semiconductor structure can improve the crystal quality of the doped thick film gallium nitride layer, contribute to the automatic peeling of the subsequent doped thick film gallium nitride layer, reduce the series resistance of the device, and increase the tunneling current.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and particularly to a semiconductor structure, a self-supporting gallium nitride layer and a method for preparing the same. Background Art

[0002] With the development of science and technology, semiconductor devices with excellent properties such as high frequency, high efficiency and high power are applied in more and more fields. The third-generation semiconductor materials represented by gallium nitride (GaN) have excellent physical and chemical properties such as wide bandgap, high thermal conductivity and corrosion resistance, and have broad application prospects in optoelectronic devices and microelectronic devices.

[0003] Currently, the method of hydride vapor phase epitaxy (HVPE) is mainly used to prepare single-crystal gallium nitride thick films. The preparation of single-crystal gallium nitride by HVPE is carried out in a hydride vapor phase epitaxy device. Gallium nitride single crystals are obtained by introducing growth materials into the hydride vapor phase epitaxy device and deposited on a substrate (or seed) to epitaxially form gallium nitride single crystals. In the above method, there is a technology of using a mask for gallium nitride growth, that is, a mask is plated on a hetero-substrate, and gallium nitride cannot epitaxially grow on the mask and can only grow within the mask opening. Finally, lateral epitaxial overgrowth technology is used for closing.

[0004] However, this method is prone to dislocation inconsistency above the opening and above the mask (such as the lateral closing position) in the initial stage of growth, which further affects the improvement of quality, and the product performance is difficult to meet the requirements. Summary of the Invention

[0005] Based on this, in view of the above deficiencies in the prior art, it is necessary to provide a semiconductor structure, a self-supporting gallium nitride layer and a method for preparing the same.

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

[0007] Providing a substrate; and forming a patterned mask layer on the surface of the substrate, wherein the patterned mask layer has a plurality of openings;

[0008] Placing the substrate with the patterned mask layer formed thereon into a hydride vapor phase epitaxy device;

[0009] Forming a gallium nitride seed layer within the opening and on the surface of the patterned mask layer facing away from the substrate, the gallium nitride seed layer including a first region within the opening and a second region on the surface of the patterned mask layer facing away from the substrate, and the dislocation density in the first region is greater than the dislocation density in the second region;

[0010] Etch the gallium nitride seed layer to completely remove the gallium nitride seed layer in the first region or make the thickness of the gallium nitride seed layer in the first region less than the thickness of the gallium nitride seed layer in the second region;

[0011] Introduce a doping gas into the hydride vapor phase epitaxy equipment to form a doped thick film gallium nitride layer, and the doped thick film gallium nitride layer fills the opening and covers the remaining gallium nitride seed layer.

[0012] In the method for preparing a semiconductor structure provided in the above embodiment, after etching the obtained structure to remove part or all of the gallium nitride seed layer in the first region, using the gallium nitride seed layer in the second region as a seed, and performing lateral epitaxial growth again to form a doped thick film gallium nitride layer, it is possible to avoid the problem that the dislocations above the opening and above the patterned mask layer (such as the lateral closing part) are inconsistent during the initial growth of gallium nitride, which affects the improvement of quality and the product performance is difficult to meet the requirements, improve the crystal quality of the doped thick film gallium nitride layer, and contribute to the automatic peeling of the subsequent doped thick film gallium nitride layer; at the same time, a doped thick film gallium nitride layer is also formed. Compared with the undoped gallium nitride layer, the doped thick film gallium nitride layer can increase the electron density per unit area by increasing the doping concentration of gallium nitride, thereby reducing the series resistance of the device and increasing the tunneling current.

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

[0014] Introduce a reaction gas including hydrogen chloride and ammonia into the hydride vapor phase epitaxy equipment to form the gallium nitride seed layer in the opening and on the surface of the patterned mask layer facing away from the substrate.

[0015] In one embodiment, etching the gallium nitride seed layer includes:

[0016] Stop introducing ammonia into the hydride vapor phase epitaxy equipment and continuously introduce hydrogen chloride into the hydride vapor phase epitaxy equipment, and use the hydrogen chloride to etch the gallium nitride seed layer.

[0017] In one embodiment, during the process of continuously introducing hydrogen chloride into the hydride vapor phase epitaxy equipment, continuously reduce the flow rate of the hydrogen chloride to a preset flow rate, and the hydrogen chloride etches the gallium nitride seed layer at the preset flow rate.

[0018] In one embodiment, 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. Before forming the doped thick film gallium nitride layer after etching the gallium nitride seed layer, it further includes:

[0019] Stop introducing the hydrogen chloride gas into the hydride vapor phase epitaxy device, and only introduce the carrier gas into the hydride vapor phase epitaxy device.

[0020] In one embodiment, introducing a doping gas into the hydride vapor phase epitaxy device to form a doped thick film gallium nitride layer includes:

[0021] Continue to introduce a reaction gas including hydrogen chloride and ammonia into the hydride vapor phase epitaxy device;

[0022] Introduce the doping gas into the hydride vapor phase epitaxy device for at least a period of time while continuing to introduce the reaction gas including hydrogen chloride and ammonia into the hydride vapor phase epitaxy device to form the doped thick film gallium nitride layer.

[0023] In one embodiment, the doping gas contains at least one of at least one of a carbon gas, an iron-containing gas, a mixed gas of a carbon-containing gas and a premixed gas, and a mixed gas of an iron-containing gas and a premixed gas.

[0024] Based on the same inventive concept, the present application also provides, according to some embodiments, a semiconductor structure prepared by using the preparation method of the semiconductor structure described in any of the foregoing embodiments.

[0025] Based on the same inventive concept, the present application also provides, according to some embodiments, a method for preparing a self-supporting doped gallium nitride layer, including:

[0026] Prepare the semiconductor structure by using the preparation method of the semiconductor structure described in any of the foregoing embodiments;

[0027] Cool down the semiconductor structure so that the doped thick film gallium nitride layer is automatically peeled off to obtain a self-supporting doped gallium nitride layer.

[0028] Based on the same inventive concept, the present application also provides, according to some embodiments, a self-supporting doped gallium nitride layer, characterized in that the self-supporting doped gallium nitride layer is prepared by using the preparation method of the self-supporting doped gallium nitride layer described in the foregoing embodiments. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1Flow chart of a method for preparing a semiconductor structure provided by one embodiment of the present application;

[0031] Figure 2 In the method for preparing a semiconductor structure provided by one embodiment of the present application, schematic cross-sectional structure diagram of the structure obtained in step S20;

[0032] Figure 3 In the method for preparing a semiconductor structure provided by one embodiment of the present application, schematic cross-sectional structure diagram of the structure obtained in step S30;

[0033] Figure 4 In the method for preparing a semiconductor structure provided by one embodiment of the present application, schematic cross-sectional structure diagram of the structure obtained in step S40;

[0034] Figure 5 In the method for preparing a semiconductor structure provided by one embodiment of the present application, flow chart of step S50;

[0035] Figure 6 In the method for preparing a semiconductor structure provided by one embodiment of the present application, schematic cross-sectional structure diagram of the structure obtained in step S502; Figure 6 Also schematic cross-sectional structure diagram of a semiconductor structure provided by one embodiment of the present application;

[0036] Figure 7 Flow chart of a method for preparing a self-supporting gallium nitride layer provided by one embodiment of the present application.

[0037] Description of reference numerals:

[0038] 10. Substrate; 20. Patterned mask layer; 30. Opening; 40. Gallium nitride seed layer; 401. First region; 402. Second region; 50. Doped thick film gallium nitride layer. Detailed implementation manners

[0039] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. Preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0041] It should 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 there can be intervening elements or layers.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application herein 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 related listed items.

[0043] In the case of using "comprising", "having", and "including" described herein, unless a clear limiting term is used, such as "only", "consisting of", etc., another component can also be added. Unless otherwise mentioned, terms in the singular form can include the plural form and should not be construed as having a quantity of one.

[0044] Traditional methods for preparing single-crystalline gallium nitride thick films are prone to dislocation inconsistency above the openings and above the mask (such as at the lateral closure) during the initial growth stage, which in turn affects the improvement of quality, and it is difficult to meet the requirements of product performance.

[0045] Based on the above deficiencies in the prior art, according to some embodiments, this application provides a method for preparing a semiconductor structure. Specifically, as Figure 1 shown, the preparation method may include the following steps:

[0046] S10: Provide a substrate; and form a patterned mask layer on the surface of the substrate, and there are several openings in the patterned mask layer;

[0047] S20: Place the substrate with the patterned mask layer formed thereon into a hydride vapor epitaxy device;

[0048] S30: Form a gallium nitride seed layer in the openings and on the surface of the patterned mask layer facing away from the substrate. The gallium nitride seed layer includes a first region in the openings and a second region on the surface of the patterned mask layer facing away from the substrate, and the dislocation density in the first region is greater than the dislocation density in the second region;

[0049] S40: Etch the gallium nitride seed layer to completely remove the gallium nitride seed layer in the first region, or make the thickness of the gallium nitride seed layer in the first region less than the thickness of the gallium nitride seed layer in the second region;

[0050] S50: Introduce a doping gas into the hydride vapor epitaxy device to form a doped thick film gallium nitride layer, and the doped thick film gallium nitride layer fills the openings and covers the remaining gallium nitride seed layer.

[0051] In the process of forming a gallium nitride seed layer on the surface of the patterned mask layer facing away from the substrate and within the openings, since initially gallium nitride only grows at the openings, the vertical growth rate is relatively large, and due to the lattice mismatch between the epitaxially grown gallium nitride and the hetero-substrate, a large number of dislocations extend in the vertical direction as gallium nitride grows, forming a first region with dislocation concentration and a relatively high dislocation density; when the thickness of the deposited gallium nitride exceeds the thickness of the patterned mask layer, while gallium nitride grows vertically and gradually thickens, it begins to grow laterally by epitaxy. As the lateral growth rate increases and after sufficient time of lateral growth by epitaxy, the gallium nitride grains at adjacent openings begin to contact, connect, and fuse. However, the dislocation density of the vertically grown gallium nitride cannot be bent significantly to conduct to the laterally grown region. Therefore, the dislocation density of gallium nitride in the laterally grown region is relatively low, forming a second region with a dislocation density lower than that of the first region. In the method for preparing a semiconductor structure provided in the above embodiment, after etching the obtained structure to remove part or all of the gallium nitride seed layer in the first region, using the gallium nitride seed layer in the second region as a seed, lateral growth by epitaxy is performed again to form a doped thick film gallium nitride layer. This can avoid the problem that the dislocations above the openings and above the patterned mask layer (such as the lateral closing part) are inconsistent at the initial stage of gallium nitride growth, which affects the improvement of quality and makes it difficult to meet the requirements of product performance, improve the crystal quality of the doped thick film gallium nitride layer, and contribute to the automatic peeling of the subsequent doped thick film gallium nitride layer.

[0052] In the method for preparing a semiconductor structure provided in the above embodiment, the gallium nitride seed layer is prepared by hydride vapor phase epitaxy (HVPE). Not only is the growth rate high, but the equipment cost is also relatively low. At the same time, the generated gallium nitride can be accurately deposited within the openings of the patterned mask layer, ensuring that initially gallium nitride only grows at the openings, with a relatively large vertical growth rate, and then while growing vertically and gradually thickening, it begins to grow laterally by epitaxy.

[0053] At the same time, in the method for preparing a semiconductor structure provided in the above embodiment, a doped thick film gallium nitride layer is also formed. Compared with an undoped gallium nitride layer, the doped thick film gallium nitride layer can increase the electron density per unit area by increasing the doping concentration of gallium nitride, thereby reducing the series resistance of the device and increasing the tunneling current.

[0054] For step S10, please refer to Figure 1 S10 in Figure 2 , provide a substrate 10; and form a patterned mask layer 20 on the surface of the substrate 10. The patterned mask layer 20 has a plurality of openings 30.

[0055] It can be understood that the present application does not specifically limit the material of the substrate 10. The substrate 10 may include one or several of a silicon substrate, a sapphire substrate, a silicon carbide substrate, a gallium arsenide substrate, an aluminum nitride substrate, or a gallium nitride substrate.

[0056] 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. At this time, 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, etc.; the patterned mask layer 20 may also be a multi-layer structure. At this time, each layer in 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, etc. 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 the same, that is, the same pattern mask is used to fabricate the patterned mask layer 20, but according to the process, the pattern of each layer is allowed to have a deformation amount not exceeding 20% from the pattern of the used mask to be qualified.

[0057] Specifically, the patterned mask layer 20 may include a silicon oxide layer, a nitride layer of silicon (SiN x ), a titanium oxide layer, a nitride layer of titanium, a zirconium oxide layer, a nitride layer of zirconium, a chromium oxide layer, a nitride layer of chromium, or a nitride layer of tungsten (WN x ), etc., one or several of them; more specifically, the patterned mask layer 20 may include a silicon carbide layer, a silicon nitride layer, a tungsten nitride layer, or a chromium oxide layer, etc., one or several of them.

[0058] The present application also does not specifically limit the thickness of the patterned mask layer 20; in one embodiment, the thickness of the patterned mask layer 20 may be 10 nm to 1000 nm, such as 10 nm, 50 nm, 70 nm, 300 nm, 500 nm, 700 nm, or 1000 nm, etc. It can be understood that the above data are only examples, and 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.

[0059] In other embodiments, the patterned mask layer 20 may also include one or several 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.

[0060] The present application also does not specifically limit the manner of forming the patterned mask layer 20. The patterned mask layer 20 can be formed by, but not limited to, processes such as molecular beam epitaxy, evaporation, or sputtering.

[0061] Meanwhile, it should be noted that the shape of the opening 30 can be set according to actual needs, and the shape of the opening 30 can be circular, elliptical or an equilateral polygon with more than 3 sides.

[0062] 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, they may be arranged in a matrix or a hexagonal array, 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 1 μm and 100 μm, such as 1 μm, 20 μm, 50 μm, 80 μm or 100 μm, etc.; In another embodiment, the center distances of adjacent openings 30 may be equal, specifically, it may be 1 μm to 100 μm, more specifically, it may be 1 μm, 20 μm, 50 μm, 80 μm or 100 μm, etc.; In another embodiment, it may also be that the horizontal distances between the centers of adjacent openings 30 are the same, and the vertical distances between the centers of adjacent openings 30 are the same, but the horizontal distance and the vertical distance may be different; In other possible embodiments, the shape of the opening 30 may be a strip-shaped opening, and the width of the strip-shaped opening may be 1 μm to 10 μm, specifically, it may be 1 μm, 5 μm or 10 μm, and the spacing between adjacent openings 30 may be 1 μm to 10 μm, specifically, it may be 1 μm, 5 μm or 10 μm.

[0063] 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.

[0064] For step S20, please refer to Figure 1 S20 in Figure 2 and place the substrate 10 formed with the patterned mask layer 20 in a hydride vapor phase epitaxy device.

[0065] For step S30, please refer to Figure 1 S30 in Figure 3 and 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. The gallium nitride seed layer 40 includes a first region 401 located in the opening 30 and a second region 402 located on the surface of the patterned mask layer 20 facing away from the substrate 10, and the dislocation density in the first region 401 is greater than the dislocation density in the second region 402.

[0066] Specifically, during 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 within the opening 30, since gallium nitride initially grows only at the opening 30, the vertical growth rate is relatively high, and due to the lattice mismatch between the epitaxially grown gallium nitride and the heterogeneous substrate 10, a large number of dislocations extend in the vertical direction as gallium nitride grows, forming a first region 401 with dislocation concentration and a relatively high dislocation density; when the thickness of the deposited gallium nitride exceeds the thickness of the patterned mask layer 20, while gallium nitride grows vertically and gradually thickens, it begins to grow laterally by epitaxy. As the lateral growth rate increases and sufficient time for lateral growth is reached, the gallium nitride grains at adjacent openings 30 begin to contact, connect, and fuse. However, the dislocation density of the vertically grown gallium nitride cannot be significantly bent and conducted to the laterally grown region. Therefore, the dislocation density of gallium nitride in the laterally grown region is relatively low, forming a second region 402 with a dislocation density lower than that of the first region 401.

[0067] Specifically, the growth temperature of the gallium nitride seed layer 40 can be set according to actual needs; in one embodiment, the growth temperature of the gallium nitride seed layer 40 is greater than 800 °C.

[0068] 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, 200 μm, or 250 μm, etc.

[0069] It can be understood that the above data are only examples, and in actual embodiments, the growth temperature and thickness of the gallium nitride seed layer 40 can be set according to actual needs and are not limited to the above data.

[0070] In one embodiment, step S30 may include the step of introducing a reaction gas including hydrogen chloride and ammonia into the metalorganic chemical vapor deposition apparatus to form the gallium nitride seed layer 40 within the opening 30 and on the surface of the patterned mask layer 20 facing away from the substrate 10.

[0071] Specifically, the flow rates of hydrogen chloride and ammonia introduced into the hydride vapor epitaxy equipment can also be set according to actual needs; in one embodiment, the flow rate of ammonia can be 0.5 slm (Standard Liter per Minute) to 10 slm, such as 0.5 slm, 1 slm, 5 slm, or 10 slm, etc.; 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, etc.

[0072] The growth time of the gallium nitride seed layer 40 can also be set according to actual needs; specifically, the growth time can be 10 min to 5 h, such as 10 min, 30 min, 1 h, 3 h, or 5 h, etc.

[0073] 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, 200 μm, or 250 μm, etc. It can be understood that the above data are only examples, and 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.

[0074] In one embodiment, the hydride vapor epitaxy equipment includes a gallium boat area and a substrate area. A gallium boat containing gallium is placed in the gallium boat area, and the structure obtained in step S20 is located in the substrate area; when hydrogen chloride in the reaction gas passes through the gallium boat area, it reacts with gallium to form gallium chloride, and the gallium chloride reacts with ammonia in the substrate area to form the gallium nitride seed layer 40.

[0075] It can be understood that the above data are only examples, and in actual embodiments, the flow rates of hydrogen chloride and ammonia introduced into the hydride vapor epitaxy equipment and the growth time of the gallium nitride seed layer 40 can all be set according to actual needs and are not limited to the above data.

[0076] For step S40, please refer to Figure 1 S40 in Figure 4 to etch the gallium nitride seed layer 40 so as to completely remove the gallium nitride seed layer 40 located in the first region 401, or to make the thickness of the gallium nitride seed layer 40 in the first region 401 less than the thickness of the gallium nitride seed layer 40 in the second region 402.

[0077] This application does not specifically limit the method of etching the gallium nitride seed layer 40 in step S40; in one embodiment, ammonia gas can be stopped from being introduced into the hydride vapor epitaxy equipment, and hydrogen chloride can be continuously introduced into the hydride vapor epitaxy equipment, and the gallium nitride seed layer 40 is etched with hydrogen chloride.

[0078] Hydrogen chloride has a higher corrosion rate in the first region with a higher dislocation density. In the method for preparing the semiconductor structure provided in the above embodiment, in-situ corrosion is carried out using the growth gas hydrogen chloride, without the need for furnace opening operation, nor the need to provide additional gas or pipelines for corrosion, and the operation is convenient; by controlling the flow rate of hydrogen chloride and the corrosion time, the gallium nitride in the first region of the gallium nitride seed layer 40 is corroded faster, and then the gallium nitride seed layer 40 in the first region gradually decreases and becomes concave or is completely corroded. The gallium nitride in the second region is retained because of its better crystal quality and smaller corrosion rate, so that the thickness of the gallium nitride seed layer 40 in the second region is larger than that in the first region. In the subsequent process, the gallium nitride in the high-quality second region can be used as a seed to carry out lateral epitaxial overgrowth of gallium nitride again to form a doped thick film gallium nitride layer 50, further improving the crystal quality of the doped thick film gallium nitride layer 50.

[0079] Specifically, after the growth of the gallium nitride seed layer 40 is completed, ammonia gas can be stopped from being introduced into the hydride vapor epitaxy equipment, and hydrogen chloride can be continuously introduced into the hydride vapor epitaxy equipment and maintained for a certain time; specifically, the maintained time can be 10 s to 100 min. For example, it can be 10 s, 1 min, 10 min, 30 min, 50 min, 60 min, 80 min or 100 min, etc.

[0080] On the basis of the above embodiment, optionally, during the process of continuously introducing hydrogen chloride into the hydride vapor epitaxy equipment, the flow rate of hydrogen chloride can be continuously reduced to a preset flow rate, and at this time, the gallium nitride seed layer 40 is etched with the preset flow rate of hydrogen chloride.

[0081] There is no limitation on the execution order between the operation of stopping the introduction of ammonia gas into the hydride vapor epitaxy equipment and the operation of reducing the flow rate of hydrogen chloride, that is, either of them can be executed first or they can be executed simultaneously; in one embodiment, ammonia gas can be stopped from being introduced into the hydride vapor epitaxy equipment and maintained for 0 min to 30 min, and then the flow rate of hydrogen chloride can be reduced; specifically, it can be maintained for 5 min, 10 min, 15 min, 20 min or 30 min, etc.

[0082] 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, etc. It can be understood that the above data are only examples, and in actual embodiments, the preset flow rate can be set according to actual needs and is not limited to the above data.

[0083] This application does not specifically limit the time required to reduce the flow rate of hydrogen chloride from the flow rate used when forming the gallium nitride seed layer 40 to the preset flow rate. Specifically, the time required to reduce to the preset flow rate can be 10 s to 30 min, such as 10 s, 30 s, 1 min, 5 min, 15 min, or 30 min, etc. It can be understood that the above data are only examples, and in actual embodiments, the time for etching the gallium nitride seed layer 40 with hydrogen chloride at the preset flow rate can be set according to actual needs and is not limited to the above data; that is to say, the flow rate of hydrogen chloride can be rapidly reduced in a short time or slowly reduced to the preset flow rate.

[0084] In one example, the time for etching the gallium nitride seed layer 40 with hydrogen chloride at the preset flow rate is 10 s to 60 min; specifically, it can be 10 s, 1 min, 10 min, 20 min, 30 min, 40 min, 50 min, or 60 min, etc.

[0085] In one of the embodiments, the temperature in the hydride vapor phase epitaxy device 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 process 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 subsequent formed doped thick film gallium nitride layer; optionally, the etching temperature during the etching process 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 to ensure the etching effect.

[0086] Specifically, in step S40, the temperature in the hydride vapor phase epitaxy device can be gradually cooled from the growth temperature of the gallium nitride seed layer 40 to the etching temperature, and after reaching the etching temperature, the step of etching the gallium nitride seed layer 40 is then executed. Of course, in other embodiments, the gallium nitride seed layer 40 can also be etched while cooling.

[0087] In one embodiment, while introducing reaction gases including hydrogen chloride and ammonia gas into the hydride vapor phase epitaxy equipment, a carrier gas is also introduced into the hydride vapor phase epitaxy equipment; on this basis, after step S40 and before step S50, the preparation method may further include a step of stopping introducing hydrogen chloride gas into the hydride vapor phase epitaxy equipment and only introducing the carrier gas into the hydride vapor phase epitaxy equipment.

[0088] This application does not specifically limit the type of the carrier gas. Specifically, the carrier gas used may include one or more of hydrogen, nitrogen, helium, and argon. It can be understood that in actual embodiments, the type of the carrier gas can be set according to actual needs. More specifically, in one embodiment, the carrier gas used includes hydrogen.

[0089] This application does not specifically limit the time for only introducing the carrier gas into the hydride vapor phase epitaxy equipment. Specifically, the time for only introducing the carrier gas into the hydride vapor phase epitaxy equipment can be 1 min to 30 min, such as 1 min, 5 min, 15 min, or 30 min, etc. It can be understood that the above data are only examples, and in actual embodiments, the time for only introducing the carrier gas into the hydride vapor phase epitaxy equipment can be set according to actual needs and is not limited to the above data.

[0090] Meanwhile, during the process of stopping introducing ammonia gas into the hydride vapor phase epitaxy equipment and continuously introducing hydrogen chloride into the hydride vapor phase epitaxy equipment, the flow rate of the carrier gas introduced into the hydride vapor phase epitaxy equipment can be the same as or different from that when forming the gallium nitride seed layer 40. Specifically, in one embodiment, the flow rate of the carrier gas introduced into the hydride vapor phase epitaxy equipment is the same as that when forming the gallium nitride seed layer 40.

[0091] For step S50, as Figure 5 shown, step S50 may specifically include the following steps:

[0092] S501: Continuously introduce reaction gases including hydrogen chloride and ammonia gas into the hydride vapor phase epitaxy equipment;

[0093] S502: Introduce a doping gas into the hydride vapor phase epitaxy equipment for at least a period of time while continuously introducing reaction gases including hydrogen chloride and ammonia gas into the hydride vapor phase epitaxy equipment to form a doped thick film gallium nitride layer 50, as Figure 6 shown.

[0094] Specifically, in step S501, ammonia gas can be first introduced into the hydride vapor phase epitaxy equipment, and then hydrogen chloride gas is introduced, and the flow rates of hydrogen chloride and ammonia are adjusted to the growth flow rates.

[0095] Specifically, the growth temperature of the doped thick-film gallium nitride layer 50 can be set according to actual needs. In one embodiment, the growth temperature of the doped thick-film gallium nitride layer 50 is greater than 900 °C.

[0096] In one embodiment, the flow rates of hydrogen chloride and ammonia gas introduced into the hydride vapor epitaxy equipment can be set according to actual needs; specifically, the flow rate of ammonia gas can be 1 slm to 30 slm, such as 1 slm, 10 slm, 20 slm or 30 slm, etc.; the flow rate of hydrogen chloride can be 100 sccm to 2000 sccm, such as 100 sccm, 250 sccm, 500 sccm, 1000 sccm or 2000 sccm, etc.

[0097] In one embodiment, the growth time of the doped thick-film gallium nitride layer 50 can be set according to actual needs; specifically, the growth time can be 1 h to 50 h, such as 1 h, 15 h, 25 h, 35 h or 50 h, etc.

[0098] It can be understood that the above data are only examples, and the growth process conditions of the doped thick-film gallium nitride layer 50 in the actual embodiment are not limited to the above data.

[0099] Specifically, the present application does not specifically limit the types of doping gases introduced into the hydride vapor epitaxy equipment in step S502; in one embodiment, the doping gas contains at least one of a carbon gas, an iron-containing gas, a mixed gas of a carbon-containing gas and a premixed gas, and a mixed gas of an iron-containing gas and a premixed gas.

[0100] Among them, the carbon-containing gas may include C n H 2n+2 (n = 1 to 10), such as one or several of methane (CH4), ethane (C2H6), propane (C3H8) or butane (C4H 10 ) ; the present application does not specifically limit the type and quantity of the premixed gas, as long as it does not react with other gases; the premixed gas may include, but is not limited to, one or several of hydrogen, nitrogen, helium or argon, etc.; in one embodiment, the volume content of the carbon-containing gas is between 0.01% and 99.99%; the iron-containing gas may include, but is not limited to, a gas containing ferrocene (Fe(C5H5)2).

[0101] Of course, in addition to the semi-insulating doping including carbon doping or iron doping as described above, the doping type in the doped gallium nitride layer 50 may also be N-type doping including silicon doping.

[0102] During the process of introducing the doping gas in step S502, the doping amount (the introduction amount of the doping source) remains constant all the time, or can also gradually increase; in one embodiment where the doping amount gradually increases, the introduction amount of the doping source can increase at a constant speed or at a variable speed; in other embodiments, doping can also be performed in one or several time periods during the process of introducing the doping gas, and the doping amounts can be the same or different.

[0103] Specifically, during the process of forming the doped thick-film gallium nitride layer 50 in step S502, doping can be carried out from the beginning of growing the doped thick-film gallium nitride layer 50, or doping can also be carried out during the process of growing the doped thick-film gallium nitride layer 50; in one embodiment, doping can also be carried out 40 min to 1.5 h after starting to grow the doped thick-film gallium nitride layer 50.

[0104] It should be noted that if the temperature in the hydride vapor phase epitaxy equipment is reduced to the etching temperature in step S40, the temperature in the hydride vapor phase epitaxy equipment still needs to be raised to the temperature required for growing the doped thick-film gallium nitride layer 50 in step S50 to ensure the growth of the doped thick-film gallium nitride layer 50.

[0105] Please continue to refer to Figure 6 , this application also provides a semiconductor structure according to some embodiments; this semiconductor structure is prepared by using the preparation method of the semiconductor structure provided in any of the foregoing embodiments, and the technical effects that can be achieved by the preparation method of the foregoing semiconductor structure can also be achieved by this semiconductor structure, which will not be elaborated here.

[0106] Based on the same inventive concept, this application also provides a preparation method of a self-supporting doped gallium nitride layer according to some embodiments. Specifically, please refer to Figure 7 , the preparation method of this self-supporting doped gallium nitride layer may include the following steps:

[0107] S1: Prepare a semiconductor structure by using the preparation method of the semiconductor structure provided in any of the foregoing embodiments;

[0108] S2: Perform a cooling treatment on the semiconductor structure so that the doped thick-film gallium nitride layer 50 is automatically peeled off to obtain a self-supporting doped gallium nitride layer.

[0109] In the above preparation method of the self-supporting gallium nitride layer, a semiconductor structure is prepared by using the preparation method of the semiconductor structure provided in any of the foregoing embodiments. Therefore, the technical effects that can be achieved by the preparation method of the foregoing semiconductor structure can also be achieved by this preparation method of the self-supporting gallium nitride layer, which will not be elaborated here; through the cooling treatment, the doped thick-film gallium nitride layer 50 can be automatically peeled off due to the thermal mismatch with the substrate 10.

[0110] It should be understood that althoughFigure 1 , Figure 5 and Figure 7 The steps in the flowcharts of Figure 1 , Figure 5 and Figure 7 are shown in sequence according to the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover,

[0111] This application also provides, according to some embodiments, a self-supporting gallium nitride layer, which is prepared by using the preparation method of the self-supporting gallium nitride layer provided in the foregoing embodiments. Therefore, the technical effects achievable by the preparation method of the foregoing self-supporting gallium nitride layer can also be achieved by this self-supporting gallium nitride layer, and details are not described herein again.

[0112] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features of the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0113] The above-described embodiments only represent several implementation manners of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of this application, several modifications and improvements can still be made, and these all belong to the protection scope of this application. Therefore, the protection scope of this application patent shall be subject to the appended claims.

Claims

1. A method for preparing a semiconductor structure, characterized in that, Comprising: Providing a substrate; And forming a patterned mask layer on the surface of the substrate, wherein the patterned mask layer has a plurality of openings; Placing the substrate with the formed patterned mask layer in a hydride vapor epitaxy device; Forming a gallium nitride seed layer in the openings and on the surface of the patterned mask layer facing away from the substrate, the gallium nitride seed layer including a first region in the openings and a second region on the surface of the patterned mask layer facing away from the substrate, and the dislocation density in the first region is greater than the dislocation density in the second region; Etching the gallium nitride seed layer to completely remove the gallium nitride seed layer in the first region, or to make the thickness of the gallium nitride seed layer in the first region less than the thickness of the gallium nitride seed layer in the second region; Introducing a doping gas into the hydride vapor epitaxy device to form a doped thick film gallium nitride layer, the doped thick film gallium nitride layer filling the openings and covering the remaining gallium nitride seed layer; Forming a gallium nitride seed layer in the openings and on the surface of the patterned mask layer facing away from the substrate, including: Introducing a reaction gas including hydrogen chloride and ammonia into the hydride vapor epitaxy device to form the gallium nitride seed layer in the openings and on the surface of the patterned mask layer facing away from the substrate; Etching the gallium nitride seed layer, including: Stopping introducing the ammonia into the hydride vapor epitaxy device, and continuously introducing the hydrogen chloride into the hydride vapor epitaxy device, and etching the gallium nitride seed layer with the hydrogen chloride.

2. The method for manufacturing a semiconductor structure according to claim 1, wherein The center distances of adjacent openings are all equal.

3. The method for preparing a semiconductor structure according to claim 1, characterized in that, The area of the openings accounts for 30% - 90% of the total area of the patterned mask layer.

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 epitaxy device, continuously reducing the flow rate of the hydrogen chloride to a preset flow rate, and etching the gallium nitride seed layer with the hydrogen chloride at the preset flow rate.

5. The method for manufacturing a semiconductor structure according to claim 3, wherein, When introducing the reaction gas into the hydride vapor epitaxy device, a carrier gas is also introduced into the hydride vapor epitaxy device. Before forming the doped thick film gallium nitride layer after etching the gallium nitride seed layer, it further includes: Stopping introducing the hydrogen chloride gas into the hydride vapor epitaxy device, and only introducing the carrier gas into the hydride vapor epitaxy device.

6. The method for preparing a semiconductor structure according to any one of claims 2 to 5, characterized in that, Introducing a doping gas into the hydride vapor epitaxy device to form a doped thick film gallium nitride layer, including: Continuing to introduce a reaction gas including hydrogen chloride and ammonia into the hydride vapor epitaxy device; Introducing the doping gas into the hydride vapor epitaxy device for at least a period of time while continuing to introduce the reaction gas including hydrogen chloride and ammonia into the hydride vapor epitaxy device to form the doped thick film gallium nitride layer.

7. The method for preparing a semiconductor structure according to claim 6, wherein The doping gas contains at least one of at least one of a carbon gas, an iron-containing gas, a mixed gas of a carbon-containing gas and a premixed gas, and a mixed gas of an iron-containing gas and a premixed gas.

8. A semiconductor structure, characterized in that, The semiconductor structure is prepared by using the preparation method of the semiconductor structure according to any one of claims 1 to 7.

9. A method for preparing a self-supporting doped gallium nitride layer, characterized in that, Comprising: The semiconductor structure is prepared by using the preparation method of the semiconductor structure according to any one of claims 1 to 7; The semiconductor structure is subjected to a cooling treatment so that the doped thick film gallium nitride layer is automatically peeled off to obtain a self-supporting doped gallium nitride layer.

10. A self-supporting doped gallium nitride layer, characterized in that, The self-supporting doped gallium nitride layer is obtained by using the preparation method of the self-supporting doped gallium nitride layer according to claim 9.

Images