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

Abstract

The application relates to a semiconductor structure, a self-supporting gallium nitride layer and a preparation method thereof, which comprises the following steps: providing a substrate; forming a patterned mask layer on the surface of the substrate; providing a hydride vapor phase epitaxy device; placing the substrate with the patterned mask layer into a substrate area; providing a first reaction gas containing hydrogen chloride to a gallium boat area through a first gas supply pipeline and providing a second reaction gas containing ammonia to the substrate area through a second gas supply pipeline to form a gallium nitride seed layer; stopping the first reaction gas from being provided to the gallium boat area and stopping the second reaction gas from being provided to the substrate area, and providing a third reaction gas containing hydrogen chloride to the substrate area through a third gas supply pipeline to completely remove the gallium nitride seed layer in a crystal grain area or make the thickness of the gallium nitride seed layer in the crystal grain area less than the thickness of the gallium nitride seed layer in an overgrowth area; and forming a thick film gallium nitride layer. The application can save raw material cost and improve the quality of the thick film gallium nitride layer.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a semiconductor structure, a self-supporting gallium nitride layer, and a method for preparing the same. Background Technology

[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-optic and photoelectric conversion efficiency to date.

[0003] Due to the difficulty in fabricating gallium nitride (GaN) single-crystal substrates, the current common practice is to prepare GaN single-crystal substrates by heteroepitaxial growth on heterogeneous substrates such as sapphire, silicon carbide, silicon, and gallium arsenide. The substrate is then peeled off from the heterogeneous substrate to obtain the GaN single-crystal substrate. One technique using a mask for GaN growth involves depositing a mask on the heterogeneous substrate. GaN cannot grow epitaxially on this mask; it can only grow within the openings of the mask. Finally, the openings are closed using lateral epitaxial growth techniques.

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

[0005] Therefore, it is necessary to address the shortcomings of the existing technology by providing a semiconductor structure, a self-supporting gallium nitride layer, and a method for fabricating the same.

[0006] According to some embodiments, this application provides a method for fabricating a semiconductor structure, including:

[0007] Provide substrate;

[0008] A patterned mask layer is formed on the surface of the substrate, and the patterned mask layer has a plurality of openings;

[0009] A hydride vapor phase epitaxy apparatus is provided, wherein the hydride vapor phase epitaxy apparatus has a substrate region and a gallium boat region arranged at intervals;

[0010] placing the substrate with the patterned mask layer formed thereon in the substrate zone; providing a first reactant gas including hydrogen chloride to the gallium boat zone via a first gas supply line and providing a second reactant gas including ammonia to the substrate zone via a second gas supply line to form a gallium nitride seed layer in the opening and on the surface of the patterned mask layer facing away from the substrate, the gallium nitride seed layer including a grain region in the opening and an overgrowth region on the surface of the patterned mask layer facing away from the substrate, a dislocation density in the grain region being greater than a dislocation density in the overgrowth region;

[0011] stopping the providing of the first reactant gas to the gallium boat zone and the providing of the second reactant gas to the substrate zone, and providing a third reactant gas including hydrogen chloride to the substrate zone via a third gas supply line, etching the gallium nitride seed layer with the hydrogen chloride to completely remove the gallium nitride seed layer in the grain region or to make a thickness of the gallium nitride seed layer in the grain region less than a thickness of the gallium nitride seed layer in the overgrowth region;

[0012] forming a thick film gallium nitride layer filling the opening and covering the remaining gallium nitride seed layer.

[0013] The preparation method of the semiconductor structure provided in the above embodiments includes the following steps: forming a patterned mask layer on a substrate; forming a gallium nitride seed layer on the substrate; etching the gallium nitride seed layer to form a thick film gallium nitride layer; and forming a gallium nitride epitaxial layer on the thick film gallium nitride layer. In the process of forming the gallium nitride seed layer, the gallium nitride is grown only at the openings at the beginning, and the vertical growth rate is relatively large. In addition, 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 with the growth of the gallium nitride, forming a grain region with 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 starts to grow laterally at the same time. With the increase of the lateral growth rate, the gallium nitride grains at adjacent openings start to contact, connect and fuse when the lateral epitaxial growth lasts for a sufficient time. However, the dislocation density of the vertically grown gallium nitride cannot be greatly bent and conducted 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 relatively low dislocation density. After the etching of the obtained structure and the removal of 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 again to perform lateral epitaxial growth to form a thick film gallium nitride layer. In this way, the problem that the dislocations are inconsistent above the openings and above the patterned mask layer (for example, at the lateral closure) at the initial stage of the growth of the gallium nitride, affecting the improvement of the quality and the performance of the product, can be avoided, the crystal quality of the thick film gallium nitride layer is improved, and the peeling of the thick film gallium nitride layer is also facilitated. In the preparation method of the semiconductor structure provided in the above embodiments, the gallium nitride generated by the reaction of ammonia, hydrogen chloride and metallic gallium can be accurately deposited in the openings of the patterned mask layer, so that the gallium nitride is grown only at the openings at the beginning, and the vertical growth rate is relatively large. Then, the gallium nitride grows vertically, and starts to grow laterally at the same time. In the preparation method of the semiconductor structure provided in the above embodiments, in the process of forming the gallium nitride seed layer, the first reaction gas is supplied to the gallium boat zone through the first gas supply pipeline, and the second reaction gas is supplied to the substrate zone through the second gas supply pipeline. In the process of removing the gallium nitride seed layer, the third reaction gas is supplied through the third gas supply pipeline, without the need of furnace opening operation. At the same time, the third reaction gas is supplied to the substrate zone through the third gas supply pipeline to remove the gallium nitride seed layer, which can avoid the reaction of the third reaction gas and the gallium in the gallium boat zone to generate additional loss, that is, save the raw material cost, and ensure the etching effect on the gallium nitride seed layer.

[0014] In one of the embodiments, the flow rate of the hydrogen chloride supplied by the third gas supply pipeline to the substrate zone is 1sccm-100sccm, and the time for which the hydrogen chloride is supplied by the third gas supply pipeline to the substrate zone is 10s-60min.

[0015] In the preparation method of the semiconductor structure provided in the above embodiments, the etching rate of the hydrogen chloride to the grain region with a high dislocation density is higher, so that the selective etching of the hydrogen chloride can be improved by controlling the flow rate and the time for which the hydrogen chloride is supplied by the third gas supply pipeline.

[0016] In one of the embodiments, before forming the thick film gallium nitride layer, further comprising:

[0017] stopping providing the third reaction gas to the substrate area via the third gas supply pipeline.

[0018] In one of the embodiments, while providing the third reaction gas to the substrate area via the third gas supply pipeline, further providing carrier gas to the substrate area via the third gas supply pipeline, after etching the gallium nitride seed layer and before forming the thick film gallium nitride layer, further comprising:

[0019] stopping providing the hydrogen chloride gas to the substrate area via the third gas supply pipeline, and only providing the carrier gas to the substrate area via the third gas supply pipeline.

[0020] after providing the carrier gas for a preset time, stopping providing the third reaction gas to the substrate area via the third gas supply pipeline.

[0021] In the method for preparing the semiconductor structure, the surface of the etched gallium nitride seed layer is cleaned by keeping in the carrier gas atmosphere for a preset time. In the process of lateral epitaxial growth for forming the thick film gallium nitride layer by using the gallium nitride seed layer in the overgrowth area as the seed again, the quality of the seed is better, so that the thick film gallium nitride layer with higher quality can be obtained, which is more helpful for the peeling of the thick film gallium nitride layer.

[0022] In one of the embodiments, the forming the thick film gallium nitride layer comprises:

[0023] continuing providing the first reaction gas to the gallium boat area via the first gas supply pipeline, and continuing providing the second reaction gas to the substrate area via the second gas supply pipeline, to form the thick film gallium nitride layer in the opening and on the surface of the remaining gallium nitride seed layer.

[0024] In one of the embodiments, the forming the thick film gallium nitride layer comprises:

[0025] continuing providing the first reaction gas to the gallium boat area via the first gas supply pipeline, and continuing providing the second reaction gas to the substrate area via the second gas supply pipeline, to form the thick film gallium nitride layer in the opening and on the surface of the remaining gallium nitride seed layer.

[0026] continuously providing the first reaction gas to the gallium boat region via the first gas supply pipe and continuously providing the second reaction gas to the substrate region via the second gas supply pipe, to perform a second thick film gallium nitride growth to obtain the thick film gallium nitride layer; the gas flow of the first reaction gas in the second thick film gallium nitride growth is greater than the gas flow of the first reaction gas in the first thick film gallium nitride growth.

[0027] In one of the embodiments, the gas flow of the first reaction gas in the first thick film gallium nitride growth is 1sccm-100sccm, and the time of the first thick film gallium nitride growth is 10min-5h; the gas flow of the first reaction gas in the second thick film gallium nitride growth is 50sccm-1000sccm, and the time of the second thick film gallium nitride growth is 1min-50h.

[0028] Based on the same inventive concept, the application also provides, according to some embodiments, a semiconductor structure prepared by the preparation method of the semiconductor structure provided in any of the preceding embodiments.

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

[0030] The semiconductor structure is prepared by the preparation method of the semiconductor structure provided in any of the preceding embodiments.

[0031] The semiconductor structure is subjected to a cooling treatment, 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 application also provides, according to some embodiments, a self-supporting gallium nitride layer, wherein the self-supporting gallium nitride layer is prepared by the preparation method of the self-supporting gallium nitride layer provided in the preceding embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0034] Figure 1 Flow chart of the preparation method of the semiconductor structure provided in one of the embodiments of the present application;

[0035] Figure 2A cross-sectional structure diagram of the structure obtained in step S20 in the method for manufacturing a semiconductor structure provided in one of the embodiments of the present application is shown in the following figure.

[0036] Figures 3 to 5 A cross-sectional structure diagram of the structure obtained in step S30 in the method for manufacturing a semiconductor structure provided in one of the embodiments of the present application is shown in the following figure.

[0037] Figure 6 A cross-sectional structure diagram of the structure obtained in step S40 in the method for manufacturing a semiconductor structure provided in one of the embodiments of the present application is shown in the following figure.

[0038] Figures 7 to 8 A cross-sectional structure diagram of the structure obtained in step S50 in the method for manufacturing a semiconductor structure provided in one of the embodiments of the present application is shown in the following figure. Figure 8 A cross-sectional structure diagram of the structure obtained in step S50 in the method for manufacturing a semiconductor structure provided in one of the embodiments of the present application is shown in the following figure.

[0039] Figure 9 A flow chart of step S60 in the method for manufacturing a semiconductor structure provided in one of the embodiments of the present application is shown in the following figure.

[0040] Figure 10 A flow chart of the method for manufacturing a self-supporting gallium nitride layer provided in one of the embodiments of the present application is shown in the following figure.

[0041] Explanation of reference numerals:

[0042] 10, substrate; 20, patterned mask layer; 30, opening; 40, gallium nitride seed layer; 401, grain region; 402, overgrowth region; 50, thick film gallium nitride layer. DETAILED DESCRIPTION

[0043] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The preferred embodiments of the present application are shown in the accompanying drawings. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided so that the disclosure of the present application is more thorough and complete.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application.

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

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0047] In the case of "comprising", "having", "including", and "containing", one or more of the specified elements can be present and additional elements can also be present unless the context clearly indicates otherwise. The term "consisting essentially of" means that the composition or process can include additional elements so long as the additional elements do not materially alter the basic and novel characteristics of the claimed composition or process.

[0048] The conventional method for preparing a gallium nitride single crystal substrate is prone to cause dislocation inconsistency above the opening and above the mask (such as a lateral closing) in the initial growth stage, thereby affecting the improvement of quality and making it difficult to meet the requirements of product performance.

[0049] Based on the above deficiencies in the prior art, according to some embodiments, a preparation method of a semiconductor structure is provided. Specifically, as shown in the figure, Figure 1 The preparation method can include the following steps:

[0050] S10: providing a substrate;

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

[0052] S30: providing a hydride vapor phase epitaxy device, the hydride vapor phase epitaxy device being provided with a substrate area and a gallium boat area arranged at intervals;

[0053] S40: placing the substrate formed with the patterned mask layer in the substrate area; providing a first reaction gas including hydrogen chloride to the gallium boat area through a first gas supply pipeline, and providing a second reaction gas including ammonia to the substrate area through a second gas supply pipeline, so as to form the gallium nitride seed layer in the openings and on the surface of the patterned mask layer away from the substrate, the gallium nitride seed layer including a grain region in the openings and an overgrowth region on the surface of the patterned mask layer away from the substrate, the dislocation density in the grain region being greater than the dislocation density in the overgrowth region;

[0054] S50: stopping the provision of the first reaction gas to the gallium boat area and the provision of the second reaction gas to the substrate area, and providing a third reaction gas including hydrogen chloride to the substrate area through a third gas supply pipeline, etching the gallium nitride seed layer by using the hydrogen chloride, so as to completely remove the gallium nitride seed layer in the grain region, or make the thickness of the gallium nitride seed layer in the grain region less than the thickness of the gallium nitride seed layer in the overgrowth region;

[0055] S60: forming a thick film gallium nitride layer, the thick film gallium nitride layer filling the openings and covering the remaining gallium nitride seed layer.

[0056] In the process of forming the gallium nitride seed layer on the surface of the patterned mask layer away from the substrate and in the openings, since the gallium nitride grows only at the openings at the beginning, the vertical growth rate is large, and the lattice mismatch between the epitaxially grown gallium nitride and the heterogeneous substrate causes a large number of dislocations to extend in the vertical direction as the gallium nitride grows, forming a grain area with a high dislocation density due to dislocation concentration. When the thickness of the deposited gallium nitride exceeds the thickness of the patterned mask layer, the gallium nitride grows vertically, gradually thickens, and then begins to grow laterally. As the lateral growth rate increases, the gallium nitride grains at adjacent openings begin to contact, connect, and fuse when the lateral epitaxial growth is sufficient. However, the dislocation density of the vertically grown gallium nitride cannot be greatly bent and conducted to the lateral growth area, so the dislocation density of the gallium nitride in the lateral growth area is relatively low, forming an overgrowth area with a lower dislocation density than the grain area. In the preparation method of the semiconductor structure provided in the above embodiments, after etching the obtained structure to remove part or all of the gallium nitride seed layer in the grain area, the gallium nitride seed layer in the overgrowth area is used as a seed again to perform lateral epitaxial growth to form a thick film gallium nitride layer. This can avoid the inconsistency of dislocations above the openings and above the patterned mask layer (such as the lateral closure) at the beginning of gallium nitride growth, which affects the improvement of quality and makes it difficult to meet the requirements of product performance. This improves the crystal quality of the thick film gallium nitride layer, and also helps to peel off the thick film gallium nitride layer. In the preparation method of the semiconductor structure provided in the above embodiments, the hydride vapor phase epitaxy (HVPE) method is used to prepare the gallium nitride seed layer 40, which has a high growth rate and 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 openings 30 of the patterned mask layer 20, so that the gallium nitride grows only at the openings 30 at the beginning, the vertical growth rate is large, and then the lateral epitaxial growth begins while the vertical growth gradually thickens.

[0057] For step S10, refer to the S10 step in Figure 1 and Figure 2 , and provide the substrate 10.

[0058] The material of the substrate 10 is not specifically limited in the present application, and the substrate 10 can 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.

[0059] For step S20, refer to the S20 step in Figure 1 and Figure 2A 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.

[0060] The present application does not make specific limitation to the structure of the patterned mask layer 20. The patterned mask layer 20 can be a single-layer structure, in which case the patterned mask layer 20 can 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 can also be a multi-layer structure, in which case each layer of the patterned mask layer 20 can 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 of the patterned mask layer 20 are consistent in principle, i.e., the same mask is used to make the patterned mask layer 20, but the patterns of each layer can be deformed by no more than 20% of the mask pattern within the process tolerance.

[0061] Specifically, the patterned mask layer 20 can include one or more of 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), etc. More specifically, the patterned mask layer 20 can include one or more of a silicon carbide layer, a silicon nitride layer, a tungsten nitride layer, or a chromium oxide layer, etc.

[0062] The present application also does not make specific limitation to 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, for example, the thickness of the patterned mask layer 20 can be 10 nm, 50 nm, 70 nm, 300 nm, 500 nm, 700 nm, or 1000 nm, etc. Preferably, the thickness of the patterned mask layer 20 is 50 nm to 700 nm, more preferably, the thickness of the patterned mask layer 20 is 70 nm to 300 nm, for example, the thickness of the patterned mask layer 20 can be 70 nm, 100 nm, 200 nm, or 300 nm, etc. It can be understood that the above data is only an example, and the thickness of the patterned mask layer 20 can be set according to actual needs in actual embodiments, and is not limited by the above data.

[0063] In other embodiments, the patterned mask layer 20 can 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.

[0064] The application is not limited to the way of forming the patterned mask layer 20. The patterned mask layer 20 can be formed by, but not limited to, molecular beam epitaxy, evaporation or sputtering process.

[0065] 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 equilateral polygon with more than 3 sides.

[0066] In one embodiment, the patterned mask layer 20 can include a plurality of openings 30, and the plurality of openings 30 can be regularly arranged, such as in a matrix arrangement or a hexagonal array arrangement, etc. In one embodiment, the circumscribed circle of the opening 30 pattern or the smallest circle that can cover the opening 30 has a diameter of 1 um to 100 um, such as 1 um, 20 um, 50 um, 80 um or 100 um, etc. In another embodiment, the center distance between adjacent openings 30 can be equal, which can be 1 um to 100 um, and more specifically, the center distance between adjacent openings 30 can be 1 um, 20 um, 50 um, 80 um or 100 um, etc. In another embodiment, the lateral distance between the centers of adjacent openings 30 can be the same, and the longitudinal distance between the centers of adjacent openings 30 can be the same, but the lateral distance and the longitudinal distance can be different. Alternatively, in all openings 30, the distance from the center of any opening 30 to the center of another adjacent opening 30 is not more than 5 different data. In other possible embodiments, the shape of the opening 30 can be a strip-shaped opening, and the width of the strip-shaped opening can be 1 um to 10 um, specifically 1 um, 5 um or 10 um, and the spacing between adjacent openings 30 can be 1 um to 10 um, specifically 1 um, 5 um or 10 um.

[0067] Optionally, in the patterned mask layer 20, the area of the opening 30 can 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, and specifically, it can be 40%, 50% or 60%, etc.

[0068] For step S30, please refer to S30 in Figure 1 , which provides a hydride vapor phase epitaxy device, wherein the hydride vapor phase epitaxy device is provided with a substrate area and a gallium boat area arranged at intervals.

[0069] For step S40, please refer to S40 in Figure 1 and Figures 3 to 5The substrate with the patterned mask layer is placed in a substrate zone; a first reaction gas including hydrogen chloride is provided to a gallium boat zone via a first gas supply pipeline, and a second reaction gas including ammonia is provided to the substrate zone via a second gas supply pipeline, so as to form a gallium nitride seed layer 40 in the openings and on the surface of the patterned mask layer away from the substrate, the gallium nitride seed layer 40 including a grain region 401 in the openings 30 and an overgrowth region 402 on the surface of the patterned mask layer 20 away from the substrate 10, the dislocation density in the grain region 401 being greater than that in the overgrowth region 402.

[0070] Specifically, in the process of forming the gallium nitride seed layer 40 on the surface of the patterned mask layer 20 away from the substrate 10 and in the openings 30, since the gallium nitride just starts to grow at the openings 30 at the beginning, as shown in FIG. 4A, the vertical growth rate is large, and the lattice mismatch between the epitaxially grown gallium nitride and the hetero-substrate 10 causes a large number of dislocations to extend in the vertical direction with the growth of the gallium nitride, forming the grain region 401 with a high dislocation density due to dislocation concentration. Figure 3 As shown in FIG. 4B, when the thickness of the deposited gallium nitride exceeds the thickness of the patterned mask layer 20, the gallium nitride grows vertically, gradually thickening while starting to grow laterally, and as the lateral growth rate increases, the gallium nitride in adjacent openings 30 starts to contact, connect and fuse when the lateral epitaxial growth is sufficient, as shown in FIG. 4C, and the dislocation density of the vertically grown gallium nitride cannot be greatly bent and conducted to the lateral growth region, so that, as shown in FIG. 4D, the dislocation density of the gallium nitride in the lateral growth region is low, forming the overgrowth region 402 with a lower dislocation density than the grain region 401. Figure 4 Figure 5

[0071] It can be understood that the growth process conditions of the gallium nitride seed layer 40 are not specifically limited in the present application.

[0072] 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.

[0073] ​​In one of the embodiments, the flow rate of the first reaction gas and the second reaction gas introduced into the hydride vapor phase epitaxy apparatus can be set according to actual needs; specifically, the flow rate of the second reaction gas can be 0.5 slm (Standard Liter per Minute) to 30 slm, for example, the flow rate of the second reaction gas can be 0.5 slm, 10 slm, 20 slm or 30 slm, and the like; the flow rate of the first reaction gas can be 20 sccm (Standard Cubic Centimeter per Minute) to 1000 sccm, for example, the flow rate of the first reaction gas can be 20 sccm, 100 sccm, 250 sccm, 500 sccm, 750 sccm or 1000 sccm, and the like.

[0074] In one of the embodiments, the growth time of the gallium nitride seed layer 40 can be set according to actual needs; specifically, the growth time can be 10 min to 5 h, for example, the growth time of the gallium nitride seed layer 40 can be 10 min, 30 min, 1 h, 3 h or 5 h, and the like.

[0075] It can be understood that the above data is only an example, and the growth process conditions of the gallium nitride seed layer 40 in the actual embodiment are not limited by the above data.

[0076] In one of the embodiments, 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, for example, 1 μm, 5 μm, 10 μm, 15 μm, 100 μm, 150 μm, 100 μm or 250 μm, and the like. It can be understood that the above data is only an example, and the thickness of the gallium nitride seed layer 40 in the actual embodiment can be set according to actual needs, and is not limited by the above data.

[0077] In one of the embodiments, while the first reaction gas and the second reaction gas are introduced into the hydride vapor phase epitaxy apparatus, a carrier gas is also introduced into the hydride vapor phase epitaxy apparatus.

[0078] The kind of the carrier gas is not specifically limited in the present application. Specifically, the carrier gas used can include one or more of hydrogen, nitrogen, helium and argon. It can be understood that the kind of the carrier gas in the actual embodiment can be set according to actual needs. More specifically, in one of the embodiments, the carrier gas used includes hydrogen.

[0079] For step S50, please refer to the S50 step in Figure 1 and the S50 step in Figure 6, stop providing the first reaction gas to the gallium boat region and stop providing the second reaction gas to the substrate region, and provide a third reaction gas including hydrogen chloride to the substrate region via a third gas supply pipeline, etch the gallium nitride seed layer with the hydrogen chloride in the third reaction gas to completely remove the gallium nitride seed layer located in the grain region 401 or make the thickness of the gallium nitride seed layer 40 located in the grain region 401 less than the thickness of the gallium nitride seed layer 40 located in the overgrowth region 402.

[0080] Specifically, the third gas supply pipeline can be an independent gas supply pipeline independent of the first gas supply pipeline and the second gas supply pipeline, and the gas outlet of the third gas supply pipeline directly extends to the substrate region to ensure that the third reaction gas directly reaches the substrate region without passing through the gallium boat region.

[0081] The above embodiment provides a preparation method of a semiconductor structure. In the process of forming the gallium nitride seed layer, the first reaction gas is provided to the gallium boat region via the first gas supply pipeline, and the second reaction gas is provided to the substrate region via the second gas supply pipeline. In the process of removing the gallium nitride seed layer, the third reaction gas is provided via the third gas supply pipeline, without opening the furnace to remove the substrate, thereby avoiding secondary pollution. At the same time, the third reaction gas is introduced into the substrate region via the third gas supply pipeline to remove the gallium nitride seed layer, which can avoid the reaction of the third reaction gas with gallium in the gallium boat region to produce additional loss, thereby saving raw material cost and ensuring the etching effect of the gallium nitride seed layer.

[0082] The hydrogen chloride has a high corrosion rate on the grain region with a high dislocation density. In the preparation method of the semiconductor structure provided by the above embodiment, the in-situ corrosion is performed by using the growth gas hydrogen chloride, without opening the furnace or providing additional gas or gas pipeline for corrosion, which is convenient to operate. By controlling the flow rate of the hydrogen chloride and the corrosion time, the gallium nitride in the grain region of the gallium nitride seed layer 40 is corroded faster, and then the gallium nitride seed layer 40 in the grain region is gradually reduced and recessed or completely corroded, while the gallium nitride in the overgrowth region is reserved due to the good crystal quality and small corrosion rate, so that the thickness of the gallium nitride seed layer 40 in the overgrowth region is greater than that in the grain region. In the subsequent process, the gallium nitride seed layer 40 with high quality in the overgrowth region can be used as a seed to perform lateral epitaxial overgrowth of gallium nitride to form the thick gallium nitride layer 50, thereby further improving the crystal quality of the thick gallium nitride layer 50.

[0083] It can be understood that the operation of stopping providing the first reaction gas to the gallium boat region and stopping providing the second reaction gas to the substrate region can be performed simultaneously with the operation of providing the third reaction gas including hydrogen chloride to the substrate region via the third gas supply pipeline. Alternatively, the operation of stopping providing the first reaction gas to the gallium boat region and stopping providing the second reaction gas to the substrate region can be performed first, and then the third reaction gas including hydrogen chloride is provided to the substrate region via the third gas supply pipeline after a certain period of time.

[0084] The application does not make specific limitation to the flow rate of hydrogen chloride provided by the third gas supply pipe to the substrate region; in one embodiment, the third gas supply pipe provides hydrogen chloride to the substrate region at a flow rate of 1 sccm to 100 sccm, for example, the flow rate of hydrogen chloride can be 1 sccm, 25 sccm, 50 sccm, 75 sccm or 100 sccm, etc. The application also does not make specific limitation to the time for which the third gas supply pipe provides hydrogen chloride to the substrate region; in one embodiment, the third gas supply pipe provides hydrogen chloride to the substrate region for a time of 10 s to 60 min, for example, the third gas supply pipe can provide hydrogen chloride to the substrate region for a time of 10 s, 5 min, 15 min, 30 min or 60 min, etc.

[0085] The preparation method of the semiconductor structure provided in the above embodiments has a higher etching rate of hydrogen chloride on the grain region with a higher dislocation density, so that the selective etching of hydrogen chloride can be improved by controlling the flow rate and time of hydrogen chloride provided by the third gas supply pipe.

[0086] In one embodiment, the preparation method further comprises the following steps after etching the gallium nitride seed layer 40 and before forming the thick gallium nitride layer 50:

[0087] Stopping providing the third reaction gas to the substrate region via the third gas supply pipe.

[0088] In another embodiment, the third reaction gas is introduced to the substrate region via the third gas supply pipe, and at the same time, a carrier gas is also introduced to the substrate region via the third gas supply pipe; at this time, the preparation method further comprises the following steps after etching the gallium nitride seed layer and before forming the thick gallium nitride layer:

[0089] Stopping introducing hydrogen chloride gas to the substrate region via the third gas supply pipe, and only introducing the carrier gas to the substrate region via the third gas supply pipe;

[0090] After introducing the carrier gas for a preset time, stopping providing the third reaction gas to the substrate region via the third gas supply pipe.

[0091] In the preparation method of the semiconductor structure provided in the above embodiments, the surface of the etched gallium nitride seed layer can be cleaned by maintaining for a preset time in the carrier gas atmosphere, so that the quality of the seed layer is better in the subsequent process of lateral epitaxial growth to form the thick gallium nitride layer by using the gallium nitride seed layer in the overgrowth region as the seed, thereby obtaining a thick gallium nitride layer with higher quality, which is more conducive to the peeling of the thick gallium nitride layer.

[0092] The preset time for introducing the carrier gas into the substrate region via the third gas supply pipeline only is not particularly limited in the present application; specifically, the preset time can be 1 min to 30 min, such as 1 min, 5 min, 15 min, or 30 min, and the like; it can be understood that the above data are only examples, and in actual embodiments, the time for introducing the carrier gas into the substrate region via the third gas supply pipeline only can be set according to actual needs, and is not limited by the above data.

[0093] The flow rate of the carrier gas during the process of introducing the carrier gas into the substrate region via the third gas supply pipeline only is not particularly limited; specifically, the flow rate of the carrier gas during the process of introducing the carrier gas into the substrate region via the third gas supply pipeline only can be the same as the flow rate of the carrier gas in other steps (for example, step S302), or can be different.

[0094] The type of the carrier gas is not particularly limited in the present application. Specifically, the carrier gas used can include one or more of hydrogen, nitrogen, helium, and argon; it can be understood that the type of the carrier gas can be set according to actual needs in actual embodiments; more specifically, in one of the embodiments, the carrier gas used includes hydrogen.

[0095] For step S60, please refer to the S60 step in Figure 1 , and Figures 7 to 8 , a thick film gallium nitride layer 50 is formed, which fills the opening 30 and covers the remaining gallium nitride seed layer 40.

[0096] The method for forming the thick film gallium nitride layer 50 is not particularly limited in the present application; specifically, after the step of etching the gallium nitride seed layer 40 is completed, the first reaction gas can be continuously supplied to the gallium boat region via the first gas supply pipeline, and the second reaction gas can be continuously supplied to the substrate region via the second gas supply pipeline, so as to form the thick film gallium nitride layer 50 in the opening and on the surface of the remaining gallium nitride seed layer 40.

[0097] In one of the embodiments, please refer to Figure 9 , step S60 can include:

[0098] S601: continue to supply the first reaction gas to the gallium boat region via the first gas supply pipeline, and supply the second reaction gas to the substrate region via the second gas supply pipeline, to perform first thick film gallium nitride growth;

[0099] S602: continue to supply the first reaction gas to the gallium boat region via the first gas supply pipeline, and continue to supply the second reaction gas to the substrate region via the second gas supply pipeline, to perform second thick film gallium nitride growth, so as to obtain a thick film gallium nitride layer; the gas flow rate of the first reaction gas during the second thick film gallium nitride growth is greater than the gas flow rate of the first reaction gas during the first thick film gallium nitride growth.

[0100] It can be understood that the application does not make specific limitation on the growth process conditions of the thick-film gallium nitride layer 50.

[0101] In one embodiment, the growth temperature of the thick-film gallium nitride layer 50 can be set according to actual needs; specifically, the growth temperature of the thick-film gallium nitride layer 50 is greater than 900℃.

[0102] The application does not make specific limitation on the size of the gas flow of the first reaction gas in the first thick-film gallium nitride growth process and the size of the gas flow of the first reaction gas in the second thick-film gallium nitride growth process, as long as the gas flow of the first reaction gas in the second thick-film gallium nitride growth process is greater than the gas flow of the first reaction gas in the first thick-film gallium nitride growth process; in one embodiment, the gas flow of the first reaction gas in the first thick-film gallium nitride growth process is 1sccm-100sccm, such as 1sccm, 25sccm, 50sccm, 75sccm or 100sccm, etc.; the gas flow of the first reaction gas in the second thick-film gallium nitride growth process is 50sccm-1000sccm, such as 50sccm, 125sccm, 250sccm, 500sccm or 1000sccm, etc.

[0103] The application also does not make specific limitation on the time of the first thick-film gallium nitride growth and the time of the second thick-film gallium nitride growth; in one embodiment, the time of the first thick-film gallium nitride growth is 10min-5h, such as 10min, 45min, 1.5h, 3h, 4h or 5h, etc.; the time of the second thick-film gallium nitride growth is 1min-50h, such as 1min, 30min, 1h, 5h, 10h, 20h, 30h, 40h or 50h, etc.

[0104] It can be understood that the above data is only an example, and the growth process conditions of the thick-film gallium nitride layer 50 are not limited by the above data in actual embodiments.

[0105] According to some embodiments, the application further provides a semiconductor structure. Please refer to Figure 8 The semiconductor structure is prepared by the preparation method of the semiconductor structure provided in any of the preceding embodiments, and the technical effects that can be achieved by the preparation method of the semiconductor structure can also be achieved by the semiconductor structure, which will not be described here in detail.

[0106] According to some embodiments, the application further provides a preparation method of a self-supporting gallium nitride layer. Please refer to Figure 10 The preparation method of the self-supporting gallium nitride layer can include the following steps:

[0107] S1: preparing the semiconductor structure by using the method for preparing a semiconductor structure provided in any one of the preceding embodiments;

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

[0109] In the method for preparing a self-supporting gallium nitride layer, the semiconductor structure is prepared by using the method for preparing a semiconductor structure provided in any one of the preceding embodiments, and thus the technical effects that can be achieved by the method for preparing a semiconductor structure are also achieved by the method for preparing a self-supporting gallium nitride layer, which will not be described here again. Through the cooling treatment, the thick gallium nitride layer 50 can be automatically peeled off due to the thermal mismatch between the thick gallium nitride layer 50 and the substrate 10.

[0110] According to some embodiments, the application further provides a self-supporting gallium nitride layer, which is prepared by using the method for preparing a self-supporting gallium nitride layer provided in the preceding embodiments, and thus the technical effects that can be achieved by the method for preparing a self-supporting gallium nitride layer are also achieved by the self-supporting gallium nitride layer, which will not be described here again.

[0111] It should be understood that, although Figure 1 , Figure 9 and Figure 10 in the flowcharts are displayed in sequence according to the arrows, these steps are not necessarily executed in sequence according to the arrows. Unless otherwise specified herein, the execution of these steps is not strictly limited in sequence, and these steps can be executed in other sequences. Moreover, Figure 1 , Figure 9 and Figure 10 may include multiple steps or stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution sequence of these steps or stages is not necessarily sequential, but can be executed in rotation or alternation with other steps or steps or stages in other steps.

[0112] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features of the above-described embodiments are described, and it should be considered that any combination of the technical features is within the scope of the present disclosure as long as the combination does not cause contradiction.

[0113] The above embodiments only express several implementation ways of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation to the patent scope of the application. It should be pointed out that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, which all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method of fabricating a semiconductor structure, characterized by, The application relates to a method for forming a thick-film gallium nitride layer on a substrate. The method comprises the following steps: providing a substrate; forming a patterned mask layer on the surface of the substrate, the patterned mask layer having a plurality of openings; providing a hydride vapor phase epitaxy device, the hydride vapor phase epitaxy device having a substrate area and a gallium boat area arranged at intervals; placing the substrate provided with the patterned mask layer in the substrate area; providing a first reaction gas containing hydrogen chloride to the gallium boat area through a first gas supply pipeline and providing a second reaction gas containing ammonia to the substrate area through a second gas supply pipeline, so as to form a gallium nitride seed layer in the openings and on the surface of the patterned mask layer away from the substrate, the gallium nitride seed layer comprising a grain area in the openings and an overgrowth area on the surface of the patterned mask layer away from the substrate, the dislocation density in the grain area being greater than that in the overgrowth area; stopping the provision of the first reaction gas to the gallium boat area and the provision of the second reaction gas to the substrate area, and providing a third reaction gas containing hydrogen chloride to the substrate area through a third gas supply pipeline, so as to etch the gallium nitride seed layer by using the hydrogen chloride, so as to completely remove the gallium nitride seed layer in the grain area or make the thickness of the gallium nitride seed layer in the grain area less than that of the gallium nitride seed layer in the overgrowth area; 2. The method of claim 1, wherein the semiconductor structure is prepared by a method comprising: continuing to provide the first reaction gas to the gallium boat area through the first gas supply pipeline and continuing to provide the second reaction gas to the substrate area through the second gas supply pipeline, so as to form a thick-film gallium nitride layer in the openings and on the surface of the remaining gallium nitride seed layer; the thick-film gallium nitride layer fills the openings and covers the remaining gallium nitride seed layer.

3. The method of claim 1, wherein the semiconductor structure is prepared by a method comprising: The flow rate of the hydrogen chloride provided by the third gas supply pipeline to the substrate area is 1-100 sccm, and the time for providing the hydrogen chloride by the third gas supply pipeline to the substrate area is 10 s-60 min. Before the step of forming the thick-film gallium nitride layer, the method further comprises the following steps:

4. The method of claim 1, wherein the semiconductor structure is prepared by a method comprising: stopping the provision of the third reaction gas to the substrate area through the third gas supply pipeline. While the third reaction gas is being introduced into the substrate area through the third gas supply pipeline, a carrier gas is also introduced into the substrate area through the third gas supply pipeline; after etching the gallium nitride seed layer and before forming the thick-film gallium nitride layer, the method further comprises the following steps: stopping the introduction of the hydrogen chloride gas into the substrate area through the third gas supply pipeline and only introducing the carrier gas into the substrate area through the third gas supply pipeline; 5. The method of claim 1, wherein the semiconductor structure is prepared by a method comprising: after the carrier gas is introduced for a preset time, stopping the provision of the third reaction gas to the substrate area through the third gas supply pipeline. The step of continuing to provide the first reaction gas to the gallium boat area through the first gas supply pipeline and continuing to provide the second reaction gas to the substrate area through the second gas supply pipeline, so as to form a thick-film gallium nitride layer in the openings and on the surface of the remaining gallium nitride seed layer, comprises the following steps: continuing to provide the first reaction gas to the gallium boat area via the first gas supply pipe and continuing to provide the second reaction gas to the substrate area via the second gas supply pipe to perform a first thick film gallium nitride growth; continuing to provide the first reaction gas to the gallium boat area via the first gas supply pipe and continuing to provide the second reaction gas to the substrate area via the second gas supply pipe to perform a second thick film gallium nitride growth to obtain the thick film gallium nitride layer; the gas flow of the hydrogen chloride during the second thick film gallium nitride growth is greater than the gas flow of the first reaction gas during the first thick film gallium nitride growth.

6. The method of claim 5, wherein the semiconductor structure is prepared by a method comprising: The gas flow of the first reaction gas during the first thick film gallium nitride growth is 1-100 sccm, and the time of the first thick film gallium nitride growth is 10 min-5 h; the gas flow of the first reaction gas during the second thick film gallium nitride growth is 50-1000 sccm, and the time of the second thick film gallium nitride growth is 1 min-50 h.

7. A semiconductor structure, characterized by The semiconductor structure is prepared by the preparation method of the semiconductor structure according to any one of claims 1-6.

8. A method of producing a self-supporting gallium nitride layer, characterized by, comprising: The semiconductor structure is prepared by the preparation method of the semiconductor structure according to any one of claims 1-6. The semiconductor structure is subjected to a cooling treatment, so that the thick film gallium nitride layer is automatically peeled off to obtain a self-supporting gallium nitride layer.

9. A self-supporting gallium nitride layer, characterized by, The self-supporting gallium nitride layer is prepared by the preparation method of the self-supporting gallium nitride layer according to claim 8. The self-supporting gallium nitride layer is prepared by the preparation method of the self-supporting gallium nitride layer according to claim 8.

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