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. The method comprises the following steps: providing a substrate, forming a patterned mask layer on the surface of the substrate; placing the substrate provided 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 providing the first reaction gas and the second reaction gas 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 first area or make the thickness of the gallium nitride seed layer in the first area smaller than the thickness of the gallium nitride seed layer in a second area; and forming a doped thick film gallium nitride layer. The application can improve the quality of the doped thick film gallium nitride layer, help automatic peeling of the doped thick film gallium nitride layer, reduce the series resistance of a device, and increase the tunneling current.

Description

TECHNICAL FIELD

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

[0002] With the development of science and technology, the application field of semiconductor devices with excellent performance such as high frequency, high efficiency and large power is more and more. The third generation semiconductor material represented by gallium nitride (GaN) has excellent physical and chemical properties such as wide band gap, high thermal conductivity and corrosion resistance, and has wide application prospect in optoelectronic devices and microelectronic devices.

[0003] At present, a hydride vapor phase epitaxy (HVPE) method is mainly used to prepare a single crystal gallium nitride thick film. The single crystal gallium nitride prepared by HVPE is carried out in a hydride vapor phase epitaxy device, and a gallium nitride single crystal is obtained by introducing a growth material into the hydride vapor phase epitaxy device and deposited on a substrate (or seed crystal) to epitaxially form a gallium nitride single crystal. In the above method, there is a technology of using a mask to grow gallium nitride, that is, a layer of mask is plated on a heterogeneous substrate, and gallium nitride cannot be epitaxially grown on the mask, but can only be grown in the opening of the mask, and finally a lateral epitaxial overgrowth technology is used to close it.

[0004] However, this method is prone to cause dislocation inconsistency at the top of the opening and the top of the mask (such as the lateral closing position) in the initial growth stage, thereby affecting the improvement of quality and making it difficult to meet the requirements of product performance. SUMMARY

[0005] Therefore, it is necessary to provide a semiconductor structure, a self-supporting gallium nitride layer and a preparation method thereof in view of the above problems in the prior art.

[0006] According to some embodiments of the present application, a preparation method of a semiconductor structure is provided, which comprises the following steps:

[0007] providing a substrate; and forming a patterned mask layer on the surface of the substrate, the patterned mask layer having a plurality of openings therein;

[0008] 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; and placing the substrate provided with the patterned mask layer in the substrate area;

[0009] providing a first reaction gas including hydrogen chloride to the gallium boat region via a first gas supply line and providing a second reaction gas including ammonia to the substrate region via a second gas supply line 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 including a first region in the openings and a second region on the surface of the patterned mask layer away from the substrate, a dislocation density in the first region being greater than a dislocation density in the second region;

[0010] stopping the providing of the first reaction gas to the gallium boat region and stopping the providing of the second reaction gas to the substrate region, and providing a third reaction gas including hydrogen chloride to the substrate region via a third gas supply line to etch the gallium nitride seed layer with the hydrogen chloride to completely remove the gallium nitride seed layer in the first region or to make a thickness of the gallium nitride seed layer in the first region less than a thickness of the gallium nitride seed layer in the second region;

[0011] introducing a dopant gas into the hydride vapor phase epitaxy apparatus and continuing to introduce the first reaction gas and the second reaction gas into the hydride vapor phase epitaxy apparatus 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.

[0012] The method for preparing a semiconductor structure provided by the above embodiment can avoid the problem that the dislocation density is inconsistent at the top of the openings and the top of the patterned mask layer (for example, the lateral closure) in the initial growth of the gallium nitride, which affects the improvement of the quality and makes it difficult to meet the requirements of the product performance, and can improve the crystal quality of the doped thick film gallium nitride layer, which is helpful to the automatic peeling of the doped thick film gallium nitride layer. Meanwhile, the doped thick film gallium nitride layer is formed, and compared with the non-doped gallium nitride layer, the doped thick film gallium nitride layer can reduce the series resistance of the device and increase the tunneling current by improving the doping concentration of the gallium nitride and increasing the electron density per unit area. In the method for preparing a semiconductor structure provided by the above embodiment, the first reaction gas is provided to the gallium boat region via the first gas supply line and the second reaction gas is provided to the substrate region via the second gas supply line in the process of forming the gallium nitride seed layer, and the third reaction gas is provided via the third gas supply line in the process of removing the gallium nitride seed layer, which does not need to open the furnace and avoids pollution. The third reaction gas is introduced into the substrate region via the third gas supply line to remove the gallium nitride seed layer, which can avoid the additional loss caused by the valence reaction of the third reaction gas with the gallium boat region, that is, save the cost and ensure the etching effect of the gallium nitride seed layer.

[0013] In one of the embodiments, the third gas supply pipe provides the hydrogen chloride to the substrate region at a flow rate of 1-100 sccm for a time period of 10 s-60 min.

[0014] In the method for preparing the semiconductor structure provided in the above embodiments, the etching rate of the hydrogen chloride on the first region with high dislocation density is higher, so that the selective etching of the hydrogen chloride can be improved by controlling the flow rate and time period of the hydrogen chloride provided by the third gas supply pipe.

[0015] In one of the embodiments, while the third reaction gas is supplied to the substrate region through the third gas supply pipe, a carrier gas is also supplied to the substrate region through the third gas supply pipe, and the method further comprises:

[0016] stopping the supply of the hydrogen chloride gas to the substrate region through the third gas supply pipe, and supplying only the carrier gas to the substrate region through the third gas supply pipe;

[0017] after the carrier gas is supplied for a preset time period, stopping the supply of the third reaction gas to the substrate region through the third gas supply pipe.

[0018] In the method for preparing the semiconductor structure provided in the above embodiments, the surface of the etched gallium nitride seed layer can be cleaned by protection in the carrier gas atmosphere for a preset time period, so that the quality of the seed layer is better in the process of lateral epitaxial growth for forming the doped thick film gallium nitride layer by using the gallium nitride seed layer of the second region as the seed layer again, thereby obtaining a higher quality of the subsequent gallium nitride layer, which is more conducive to the peeling of the doped subsequent gallium nitride layer.

[0019] In one of the embodiments, the doped gas is supplied to the hydride vapor phase epitaxy device, and the supply of the first reaction gas and the second reaction gas to the hydride vapor phase epitaxy device is continued to form a doped thick film gallium nitride layer, which comprises:

[0020] the supply of the first reaction gas to the gallium boat region through the first gas supply pipe is continued, and the supply of the second reaction gas to the substrate region through the second gas supply pipe is continued;

[0021] the doped gas is supplied to the hydride vapor phase epitaxy device for at least a time period during which the first reaction gas is supplied to the gallium boat region through the first gas supply pipe and the second reaction gas is supplied to the substrate region through the second gas supply pipe to form the doped thick film gallium nitride layer.

[0022] In one of the embodiments, a dopant gas is introduced into the hydride vapor phase epitaxy apparatus, and the first reaction gas and the second reaction gas continue to be introduced into the hydride vapor phase epitaxy apparatus to form a doped thick film gallium nitride layer, comprising:

[0023] The first reaction gas continues to be supplied to the gallium boat area through the first gas supply pipeline, and the second reaction gas continues to be supplied to the substrate area through the second gas supply pipeline to perform a first thick film gallium nitride growth;

[0024] The first reaction gas continues to be supplied to the gallium boat area through the first gas supply pipeline, and the second reaction gas continues to be supplied to the substrate area through the second gas supply pipeline, and the dopant gas is introduced into the hydride vapor phase epitaxy apparatus at least for a period of time during which the first reaction gas is supplied to the gallium boat area through the first gas supply pipeline and the second reaction gas is supplied to the substrate area through the second gas supply pipeline to perform a second thick film gallium nitride growth to form the doped 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.

[0025] In one of the embodiments, the gas flow rate of the first reaction gas during the first thick film gallium nitride growth is 1sccm-100sccm, and the time for the first thick film gallium nitride growth is 10min-5h; the gas flow rate of the first reaction gas during the second thick film gallium nitride growth is 50sccm-1000sccm, and the time for the second thick film gallium nitride growth is 1min-50h.

[0026] In one of the embodiments, the doped thick film gallium nitride layer comprises a semi-insulating doped thick film gallium nitride layer, and the dopant gas at least comprises at least one of a carbon-containing 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.

[0027] In one of the embodiments, the doped thick film gallium nitride layer comprises an N-type doped thick film gallium nitride layer, and the dopant gas at least comprises at least one of a silicon-containing gas and a mixed gas of a silicon-containing gas and a premixed gas.

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

[0029] 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, comprising:

[0030] The semiconductor structure is prepared by using the preparation method of the semiconductor structure according to any one of the preceding embodiments.

[0031] 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.

[0032] Based on the same inventive concept, the 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 according to the preceding embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in 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 any creative effort on the basis of these drawings.

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

[0035] Figure 2 Cross-sectional structure schematic diagram of the structure obtained in step S10 in the preparation method of the semiconductor structure provided for one of the embodiments of the present application;

[0036] Figure 3 Cross-sectional structure schematic diagram of the structure obtained in step S30 in the preparation method of the semiconductor structure provided for one of the embodiments of the present application;

[0037] Figure 4 Cross-sectional structure schematic diagram of the structure obtained in step S40 in the preparation method of the semiconductor structure provided for one of the embodiments of the present application;

[0038] Figure 5 Flow chart of step S50 in the preparation method of the semiconductor structure provided for one of the embodiments of the present application;

[0039] Figure 6 Cross-sectional structure schematic diagram of the structure obtained in step S502 in the preparation method of the semiconductor structure provided for one of the embodiments of the present application; Figure 6 Also provided is a cross-sectional structure schematic diagram of the semiconductor structure provided for one of the embodiments of the present application;

[0040] Figure 7 Flow chart of the preparation method of the self-supporting gallium nitride layer provided for one of the embodiments of the present application.

[0041] Reference Signs List:

[0042] 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 DESCRIPTION

[0043] For the purpose of promoting an understanding of the application, the application will now be described in greater detail with reference to the figures illustrative of preferred embodiments. The preferred embodiments described herein are intended to be illustrative only and the application is not limited to these embodiments. Rather, the application is limited only as described in the appended claims.

[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 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.

[0045] It will be understood that when an element or layer is referred to as being "on" another element or layer, it can be directly on another element or layer or intervening elements or layers can 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. The term "and / or" includes any and all combinations of one or more of the associated listed items.

[0047] In the case of using "include", "have", and "contain" described herein, unless an explicit limiting term is used, such as "only", "consisting of", and the like, another component can be added. Unless otherwise mentioned, the singular form of the term can include the plural form, and it cannot be understood as one in number.

[0048] The conventional method for preparing a single-crystal gallium nitride thick film 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, the preparation method can include the following steps: Figure 1 The preparation method can include the following steps:

[0050] S10: providing a substrate; and forming a patterned mask layer on a surface of the substrate, the patterned mask layer having a plurality of openings therein;

[0051] S20: providing a hydride vapor phase epitaxy apparatus, the hydride vapor phase epitaxy apparatus having a substrate region and a gallium boat region arranged in an interval; and placing the substrate having the patterned mask layer formed thereon in the substrate region;

[0052] S30: providing a first reaction gas including hydrogen chloride to the gallium boat region via a first gas supply pipe, and providing a second reaction gas including ammonia to the substrate region via a second gas supply pipe, to form a gallium nitride seed layer in the openings and on a 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, a dislocation density in the first region being greater than a dislocation density in the second region;

[0053] S40: stopping providing the first reaction gas to the gallium boat region, and stopping providing the second reaction gas to the substrate region, and providing a third reaction gas including hydrogen chloride to the substrate region via a third gas supply pipe, etching the gallium nitride seed layer by the hydrogen chloride to completely remove the gallium nitride seed layer in the first region, or to make a thickness of the gallium nitride seed layer in the first region less than a thickness of the gallium nitride seed layer in the second region;

[0054] S50: introducing a doping gas into the hydride vapor phase epitaxy apparatus, and continuing to introduce the first reaction gas and the second reaction gas into the hydride vapor phase epitaxy apparatus, 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.

[0055] During the formation of gallium nitride (GaN) seed layers on the surface of the patterned mask layer away from the substrate and within the openings, GaN initially grows only at the openings, resulting in a high vertical growth rate. Furthermore, lattice mismatch between the epitaxially grown GaN and the heterogeneous substrate causes numerous dislocations to extend vertically with the growth of GaN, forming a first region with concentrated dislocations and high dislocation density. When the deposited GaN thickness exceeds the thickness of the patterned mask layer, GaN begins to grow laterally while simultaneously increasing in thickness. As the lateral growth rate increases and sufficient time is allowed for lateral epitaxial growth, GaN grains at adjacent openings begin to contact, connect, and fuse. Meanwhile, the dislocation density from vertical growth cannot be significantly reduced by bending and conducting. The gallium nitride dislocation density is lower in the lateral growth region, forming a second region with a lower dislocation density than the first region. In the semiconductor structure fabrication method provided in the above embodiment, after etching the obtained structure to remove the gallium nitride seed layer in the first region, the gallium nitride seed layer in the second region is used as a seed for lateral epitaxial growth again to form a doped thick gallium nitride layer. This can avoid the problem of dislocation inconsistency above the opening and above the patterned mask layer (e.g., the lateral closure) in the early stage of gallium nitride growth, which affects the improvement of quality and makes it difficult for the product performance to meet the requirements. It improves the crystal quality of the doped thick gallium nitride layer and helps the automatic stripping of the doped thick gallium nitride layer in the later stage.

[0056] In the semiconductor structure fabrication method provided in the above embodiments, gallium nitride seed layer is prepared by hydride vapor phase epitaxy (HVPE), which not only has a high growth rate but also low equipment cost. At the same time, the gallium nitride generated by the reaction can be accurately deposited in the opening of the patterned mask layer, ensuring that gallium nitride grows only at the opening at the beginning, with a large vertical growth rate. Then, while growing vertically and gradually thickening, lateral epitaxial growth begins.

[0057] Meanwhile, in the semiconductor structure fabrication method provided in the above embodiments, a doped thick-film gallium nitride layer is also formed. Compared with the undoped gallium nitride layer, the doped thick-film gallium nitride layer increases the doping concentration of gallium nitride. The doping in the gallium nitride layer after doping can include silicon-doped N-type doping, or carbon-doped or iron-doped semi-insulating doping.

[0058] For step S10, please refer to... Figure 1 See S10 in the middle. Figure 2 A substrate 10 is provided; and a patterned mask layer 20 is formed on the surface of the substrate 10, the patterned mask layer 20 having a plurality of openings 30.

[0059] It can be understood that the material of the substrate 10 is not 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.

[0060] The structure of the patterned mask layer 20 is not limited in the present application. 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 pattern of each layer can be deformed by no more than 20% of the mask pattern according to the process.

[0061] Specifically, the patterned mask layer 20 can include one or more of a silicon oxide layer, a silicon nitride layer (SiN x ), 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 ). 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 thickness of the patterned mask layer 20 is not limited in the present application. 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. 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 method for forming the patterned mask layer 20 is not limited in the present application. The patterned mask layer 20 can be formed by, but not limited to, molecular beam epitaxy, evaporation, or sputtering, etc.

[0065] It should also be noted that the shape of the opening 30 can be set according to actual needs. The shape of the opening 30 can be a circle, an ellipse, or an equilateral shape with more than 3 sides.

[0066] In one embodiment, the patterned mask layer 20 may include a plurality of openings 30, which may be arranged regularly, for example, in a matrix or a hexagonal array. In one embodiment, the diameter of the circumscribed circle of the opening 30 pattern or the smallest circle covering the opening 30 is between 1 μm and 100 μm; for example, the diameter of the smallest circle may be 1 μm, 20 μm, 50 μm, 80 μm, or 100 μm. In another embodiment, the center distance between adjacent openings 30 may be equal, specifically between 1 μm and 100 μm. More specifically, the center distance between adjacent openings 30 may be equal to the center distance between adjacent openings 30. The center distance of the openings 30 can be 1μm, 20μm, 50μm, 80μm or 100μm, 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; in other possible embodiments, the shape of the openings 30 can be a strip opening, the width of the strip opening can be 1μm to 10μm, specifically 1μm, 5μm or 10μm, and the spacing between adjacent openings 30 can be 1μm to 10μm, specifically 1μm, 5μm or 10μm.

[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, specifically, it can be 40%, 50%, or 60%, etc.

[0068] For step S20, please refer to... Figure 1 S20 in the middle Figure 2 A hydride vapor phase epitaxy apparatus is provided, wherein a substrate region and a gallium boat region are arranged at intervals in the hydride vapor phase epitaxy apparatus; a substrate 10 with a patterned mask layer 20 is placed in the substrate region.

[0069] For step S30, please refer to... Figure 1 See S30 in the middle. Figure 3The first reaction gas including hydrogen chloride is provided to the gallium boat area through the first gas supply pipeline, and the second reaction gas including ammonia is provided to the substrate area through the second gas supply pipeline, so as to form a gallium nitride seed layer 40 in the opening 30 and on the surface of the patterned mask layer 20 away from the substrate 10. The gallium nitride seed layer 40 includes a first region 401 in the opening 30 and a second region 402 on the surface of the patterned mask layer 20 away from the substrate 10. The dislocation density in the first region 401 is greater than that in the second 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 opening 30, since the gallium nitride just starts to grow at the opening 30 at the beginning, 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 first region 401 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 20, the gallium nitride grows vertically, gradually thickens, and starts to grow laterally. With the increase of the lateral growth rate, when the lateral epitaxial growth is sufficient, the gallium nitride grains at adjacent openings 30 start to contact, connect and fuse, and the dislocation density of the vertically grown gallium nitride cannot be greatly bent and conducted to the lateral growth region. Therefore, the dislocation density of the gallium nitride in the lateral growth region is low, forming the second region 402 with a lower dislocation density than the first region 401.

[0071] 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.

[0072] 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, etc.

[0073] It can be understood that the above data is only an example, and the growth temperature and thickness of the gallium nitride seed layer 40 can be set according to actual needs in actual embodiments, and are not limited by the above data.

[0074] Specifically, the flow rate of the first reaction gas including hydrogen chloride provided to the gallium boat region via the first gas supply pipeline and the flow rate of the second reaction gas including ammonia provided to the substrate region via the second gas supply pipeline can also be set according to actual needs; in one of the embodiments, the flow rate of the second reaction gas can be 0.5 slm (Standard Liter per Minute) to 10 slm, for example, the flow rate of the second reaction gas can be 0.5 slm, 1 slm, 5 slm, or 10 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.

[0075] 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, for example, the growth time can be 10 min, 30 min, 1 h, 3 h, or 5 h, and the like.

[0076] For step S40, please refer to S40 in Figure 1 Figure 4 For step S40, please refer to S40 in Figure 1 Figure 4 , 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, and use the hydrogen chloride in the third reaction gas 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 make the thickness of the gallium nitride seed layer 40 located in the first region 401 less than the thickness of the gallium nitride seed layer 40 located in the second region 402.

[0077] 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, so as to ensure that the third reaction gas directly reaches the substrate region without passing through the gallium boat region.

[0078] The above-mentioned embodiments provide 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 the need for furnace opening operation, avoiding pollution; by introducing the third reaction gas into the substrate region via the third gas supply pipeline to remove the gallium nitride seed layer, the additional loss caused by the reaction of the third reaction gas with the gallium boat region can be avoided, that is, the cost is saved, and the etching effect of the gallium nitride seed layer can be ensured.

[0079] The first region with high dislocation density is corroded at a high rate by hydrogen chloride. In the method for preparing a semiconductor structure provided in the above embodiment, in-situ corrosion is performed using the growth gas hydrogen chloride, without the need for furnace opening operation, and without the need for providing additional gas or gas path for corrosion, thus being convenient to operate. 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 first region of the gallium nitride seed layer 40 is gradually reduced and recessed or corroded completely, and the gallium nitride in the second region is reserved due to the good crystal quality and the small 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 this way, in the subsequent process, the gallium nitride seed layer 40 with high quality in the second region can be used as a seed to perform lateral epitaxial overgrowth of gallium nitride again to form the doped thick film gallium nitride layer 50, so as to further improve the crystal quality of the doped thick film gallium nitride layer 50.

[0080] It can be understood that the operation of stopping the first reaction gas from being supplied to the gallium boat region and stopping the second reaction gas from being supplied to the substrate region can be performed simultaneously with the operation of supplying the third reaction gas including hydrogen chloride to the substrate region via the third gas supply pipeline; or the operation of stopping the first reaction gas from being supplied to the gallium boat region and stopping the second reaction gas from being supplied to the substrate region can be performed first, and then the third reaction gas including hydrogen chloride is supplied to the substrate region via the third gas supply pipeline after a certain time.

[0081] The application does not make specific limitation on the flow rate of hydrogen chloride supplied to the substrate region by the third gas supply pipeline; in one of the embodiments, the flow rate of hydrogen chloride supplied to the substrate region by the third gas supply pipeline is 1sccm-100sccm, for example, the flow rate of hydrogen chloride can be 1sccm, 25sccm, 50sccm, 75sccm or 100sccm, etc. The application also does not make specific limitation on the time for supplying hydrogen chloride to the substrate region by the third gas supply pipeline; in one of the embodiments, the time for supplying hydrogen chloride to the substrate region by the third gas supply pipeline is 10s-60min, for example, the time for supplying hydrogen chloride to the substrate region by the third gas supply pipeline can be 10s, 5min, 15min, 30min or 60min, etc.

[0082] In the method for preparing a semiconductor structure provided in the above embodiment, the grain region with high dislocation density is corroded at a higher rate by hydrogen chloride, so that the selective corrosion of hydrogen chloride can be improved by controlling the flow rate and time of hydrogen chloride supplied by the third gas supply pipeline.

[0083] In another embodiment, while the third reaction gas is introduced into the substrate region via the third gas supply pipeline, a carrier gas is also introduced into the substrate region via the third gas supply pipeline; at this time, after etching the gallium nitride seed layer and before forming the thick film gallium nitride layer, the method further includes:

[0084] stopping the supply of hydrogen chloride gas to the substrate region via the third gas supply line and supplying only a carrier gas to the substrate region via the third gas supply line;

[0085] After the carrier gas is supplied for the preset time, the supply of the third reaction gas to the substrate region via the third gas supply line is stopped.

[0086] The method for manufacturing a semiconductor structure provided by the above embodiment can clean the surface of the etched gallium nitride seed layer by maintaining the carrier gas atmosphere for a preset time. In the process of using the gallium nitride seed layer in the overgrowth region as a seed to perform lateral epitaxial growth again to form a thick gallium nitride layer, the quality of the seed is better, so that a thick gallium nitride layer with higher quality can be obtained, which is more conducive to the exfoliation of the thick gallium nitride layer.

[0087] The present application does not make a specific limitation on the preset time for supplying only the carrier gas to the substrate region via the third gas supply line; specifically, the preset time 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 is only an example, and the time for supplying only the carrier gas to the substrate region via the third gas supply line in the actual embodiment can be set according to actual needs, and is not limited by the above data.

[0088] The flow rate of the carrier gas during the process of supplying only the carrier gas to the substrate region via the third gas supply line is not specifically limited; specifically, the flow rate of the carrier gas during the process of supplying only the carrier gas to the substrate region via the third gas supply line can be the same as the flow rate of the carrier gas in other steps (for example, step S302), or can be different.

[0089] The present application does not make a specific limitation on the type of the carrier gas. 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 in the actual embodiment can be set according to actual needs; more specifically, in one of the embodiments, the carrier gas used includes hydrogen.

[0090] For step S50, please refer to Figure 1 Please refer to Figure 5 The hydride vapor phase epitaxy device is supplied with a doping gas, and the supply of the first reaction gas and the second reaction gas to the hydride vapor phase epitaxy device is continued to form a doped thick gallium nitride layer, which fills the opening and covers the remaining gallium nitride seed layer.

[0091] In one example, step S50 can comprise: continuing to provide the first reaction gas to the gallium boat region via the first gas supply pipe and continuing to provide the second reaction gas to the substrate region via the second gas supply pipe; wherein the doped gas is introduced into the hydride vapor phase epitaxy apparatus to form the doped thick film gallium nitride layer 50 for at least a period of time during which the first reaction gas is provided to the gallium boat region via the first gas supply pipe and the second reaction gas is provided to the substrate region via the second gas supply pipe.

[0092] In another example, as shown in FIG. 5B, step S50 can specifically comprise the following steps: Figure 5

[0093] S501: continuing to provide the first reaction gas to the gallium boat region via the first gas supply pipe and continuing to provide the second reaction gas to the substrate region via the second gas supply pipe to perform a first thick film gallium nitride growth;

[0094] S502: continuing to provide the first reaction gas to the gallium boat region via the first gas supply pipe and continuing to provide the second reaction gas to the substrate region via the second gas supply pipe, and introducing the doped gas into the hydride vapor phase epitaxy apparatus for at least a period of time during which the first reaction gas is provided to the gallium boat region via the first gas supply pipe and the second reaction gas is provided to the substrate region via the second gas supply pipe to perform a second thick film gallium nitride growth to form the doped 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.

[0095] It should be noted that the doped gas can be provided to the substrate region via a separate gas supply pipe.

[0096] It should be further noted that the second gallium nitride growth can be a one-step growth or a growth process comprising multiple steps; that is, the second gallium nitride growth can comprise at least two gallium nitride growth processes.

[0097] Specifically, the growth temperature of the doped thick film gallium nitride layer 50 can be set according to actual needs, and in one embodiment, the growth temperature of the doped thick film gallium nitride layer 50 is greater than 900°C.

[0098] ​The application does not make specific limitation to the gas flow of the first reaction gas in the first thick-film gallium nitride growth process and 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 that 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 1 sccm to 100 sccm, such as 1 sccm, 25 sccm, 50 sccm, 75 sccm or 100 sccm, etc.; the gas flow of the first reaction gas in the second thick-film gallium nitride growth process is 50 sccm to 1000 sccm, such as 50 sccm, 125 sccm, 250 sccm, 500 sccm or 1000 sccm, etc.

[0099] The application also does not make specific limitation to 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 10 min to 3 h, such as 10 min, 45 min, 1.5 h or 3 h, etc.; the time of the second thick-film gallium nitride growth is 1 min to 20 h, such as 1 min, 30 min, 1 h, 5 h, 10 h or 20 h, etc.

[0100] 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 are not limited to the above data in actual embodiments.

[0101] Specifically, the application does not make specific limitation to the type of the doping gas introduced into the hydride vapor phase epitaxy device in step S502.

[0102] In one embodiment, the doped thick-film gallium nitride layer 50 can be a semi-insulating doped thick-film gallium nitride layer, and at this time, the doping gas at least includes one or more of a carbon-containing gas, an iron-containing gas, a mixed gas of the carbon-containing gas and a premix gas, and a mixed gas of the iron-containing gas and the premix gas.

[0103] The carbon-containing gas can include C n H 2n+2 (n = 1-10), such as methane (CH4), ethane (C2H6), propane (C3H8) or butane (C4H 10The 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 more of hydrogen, nitrogen, helium or argon, etc.; in one embodiment, the volume content of the carbon-containing gas in the mixture of carbon-containing gas and premixed 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).

[0104] In another embodiment, the doped thick-film gallium nitride layer 50 can be an N-type doped thick-film gallium nitride layer. In this case, the doping source is an N-type dopant, such as at least one of a silicon-containing gas and a mixture of a silicon-containing gas and a premixed gas. The silicon-containing gas can include one or more of silane, monochlorosilane, dichlorosilane, trichlorosilane, and tetrachlorosilane; the premixed gas can include, but is not limited to, one or more of hydrogen, nitrogen, helium, or argon; when the doping source is a mixture of a silicon-containing gas and a premixed gas, the volume content of the silicon-containing gas in the mixture is between 0.01% and 99.99%.

[0105] In one embodiment of the N-type doped thick gallium nitride layer, the silicon doping concentration is greater than or equal to 2 × 10⁻⁶. 16 atom / cm 3 For example, the silicon doping concentration can be greater than or equal to 1 × 10⁻⁶. 17 atom / cm 3 It can also be greater than or equal to 5×10 20 atom / cm 3 Most preferably, the silicon doping concentration is greater than or equal to 1×10⁻⁶. 17 atom / cm 3 .

[0106] In another embodiment of the N-type doped thick gallium nitride layer, the silicon doping concentration can be 1×10⁻⁶. 16 atom / cm 3 ~9×10 19 atom / cm 3 Preferably, the silicon doping concentration can be 4 × 10⁻⁶. 16 atom / cm 3 ~1×10 19 atom / cm 3 More preferably, the silicon doping concentration can be 9 × 10⁻⁶. 16 atom / cm 3 ~7×10 18 atom / cm 3 Specifically, the silicon doping concentration can be 1×10⁻⁶. 17 atom / cm 3 3×1017 atom / cm 3 , 5 x 10 17 atom / cm 3 , 7 x 10 17 atom / cm 3 , 9 x 10 17 atom / cm 3 , 1 x 10 18 atom / cm 3 , 2 x 10 18 atom / cm 3 , 3 x 10 18 atom / cm 3 , 4 x 10 18 atom / cm 3 or 5 x 10 18 atom / cm 3 .

[0107] In the process of introducing the doping gas in step S502, the doping amount (the amount of the doping source introduced) can be kept constant, or gradually increased or decreased; in one embodiment in which the doping amount is gradually increased, the amount of the doping source introduced can be increased at a constant speed or at a variable speed; in other embodiments, the doping can be performed at one or more time periods in the process of introducing the doping gas, and the doping amounts can be the same or different, and can be gradually changed at one or more stages as needed.

[0108] Specifically, in the process of forming the doped thick-film gallium nitride layer 50 in step S502, the doping can be performed from the beginning of growing the doped thick-film gallium nitride layer 50, or can be performed in the process of growing the doped thick-film gallium nitride layer 50; in one embodiment, the doping can also be performed 40 min to 1.5 h after the beginning of growing the doped thick-film gallium nitride layer 50.

[0109] Please continue to refer to Figure 6 According to some embodiments, the present application also provides a semiconductor structure, which is prepared by the method for preparing a semiconductor structure according to any one of the preceding embodiments, and can achieve the technical effects of the method for preparing a semiconductor structure, which will not be described in detail here.

[0110] Based on the same inventive concept, according to some embodiments, the present application also provides a method for preparing a self-supporting doped gallium nitride layer. Specifically, please refer to Figure 7 The method for preparing a self-supporting doped gallium nitride layer can include the following steps:

[0111] S1: preparing a semiconductor structure by the method for preparing a semiconductor structure according to any one of the preceding embodiments;

[0112] S2: cooling 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.

[0113] In the method for preparing the self-supporting gallium nitride layer, the semiconductor structure is prepared by using the method for preparing the semiconductor structure provided in any of the preceding embodiments, and thus the technical effects achieved by the method for preparing the semiconductor structure are also achieved by the method for preparing the self-supporting gallium nitride layer, which will not be described here again. Through the cooling process, the doped thick film gallium nitride layer 50 can be automatically peeled off due to the thermal mismatch between the doped thick film gallium nitride layer 50 and the substrate 10.

[0114] It should be understood that, although Figure 1 , Figure 5 and Figure 7 in the flowcharts are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by 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 5 and Figure 7 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.

[0115] According to some embodiments, the present application also provides a self-supporting gallium nitride layer, which is prepared by using the method for preparing the self-supporting gallium nitride layer provided in the preceding embodiments, and thus the technical effects achieved by the method for preparing the self-supporting gallium nitride layer are also achieved by the self-supporting gallium nitride layer, which will not be described here again.

[0116] 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, but it should be understood that any combination of the technical features that does not cause contradiction is within the scope of the present application.

[0117] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be noted that, for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A method for fabricating a semiconductor structure, characterized in that, include: Provide substrate; A patterned mask layer is formed on the surface of the substrate, and the patterned mask layer has a plurality of openings. 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; the substrate on which the patterned mask layer is formed is placed in the substrate region; A first reactive gas, comprising hydrogen chloride, is supplied to the gallium boat region via a first gas supply line, and a second reactive gas, comprising ammonia, is supplied to the substrate region via a second gas supply line, so as to form a gallium nitride seed layer in the opening and on the surface of the patterned mask layer opposite to the substrate. The gallium nitride seed layer includes a first region located in the opening and a second region located on the surface of the patterned mask layer opposite to the substrate. The dislocation density in the first region is greater than the dislocation density in the second region. The supply of the first reactant gas to the gallium boat region is stopped, and the supply of the second reactant gas to the substrate region is stopped. A third reactant gas, including hydrogen chloride, is supplied to the substrate region via a third gas supply line. The hydrogen chloride is used to etch the gallium nitride seed layer to completely remove the gallium nitride seed layer located 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. The third gas supply line is an independent gas supply line separate from the first and second gas supply lines, and the outlet of the third gas supply line extends directly to the substrate region to ensure that the third reactant gas reaches the substrate region directly without passing through the gallium boat region. A doped gas is introduced into the hydride vapor phase epitaxy apparatus, and the first reactant gas and the second reactant gas are continued to be introduced into the hydride vapor phase epitaxy apparatus to form a doped thick-film gallium nitride layer, wherein the doped thick-film gallium nitride layer fills the opening and covers the retained gallium nitride seed layer.

2. The method for preparing a semiconductor structure according to claim 1, characterized in that, The flow rate of hydrogen chloride supplied to the substrate region by the third gas supply pipeline is 1 sccm to 100 sccm; the time for the third gas supply pipeline to supply hydrogen chloride to the substrate region is 10 s to 60 min.

3. The method for preparing a semiconductor structure according to claim 1, characterized in that, While the third reactive gas is introduced into the substrate region via the third gas supply line, a carrier gas is also introduced into the substrate region via the third gas supply line. After etching the gallium nitride seed layer and before forming the doped thick gallium nitride layer, the process further includes: Stop supplying the hydrogen chloride gas to the substrate region via the third gas supply line, and only supply the carrier gas to the substrate region via the third gas supply line; After the carrier gas is introduced for a preset time, the supply of the third reaction gas to the substrate region via the third gas supply pipeline is stopped.

4. The method for preparing a semiconductor structure according to any one of claims 1 to 3, characterized in that, A doped gas is introduced into the hydride vapor phase epitaxy apparatus, and the first reactant gas and the second reactant gas are continuously introduced into the hydride vapor phase epitaxy apparatus to form a doped thick-film gallium nitride layer, comprising: The first reactive gas continues to be supplied to the gallium boat region via the first gas supply line, and the second reactive gas continues to be supplied to the substrate region via the second gas supply line; The doped gas is introduced into the hydride vapor phase epitaxy apparatus for at least a period of time during which a first reactive gas is supplied to the gallium boat region via the first gas supply line and a second reactive gas is continued to be supplied to the substrate region via the second gas supply line, so as to form the doped thick film gallium nitride layer.

5. The method for preparing a semiconductor structure according to claim 4, characterized in that, A doped gas is introduced into the hydride vapor phase epitaxy apparatus, and the first reactant gas and the second reactant gas are continuously introduced into the hydride vapor phase epitaxy apparatus to form a doped thick-film gallium nitride layer, comprising: The first reactive gas is continued to be supplied to the gallium boat region via the first gas supply line, and the second reactive gas is continued to be supplied to the substrate region via the second gas supply line, so as to perform the first thick-film gallium nitride growth; A first reactive gas is continuously supplied to the gallium boat region via the first gas supply line, and a second reactive gas is continuously supplied to the substrate region via the second gas supply line. For at least a period of time, while the first reactive gas is supplied to the gallium boat region via the first gas supply line and the second reactive gas is continuously supplied to the substrate region via the second gas supply line, the doped gas is introduced into the hydride vapor phase epitaxy apparatus to perform a second thick-film gallium nitride growth, thereby forming the doped thick-film gallium nitride layer. During the second thick-film gallium nitride growth, the gas flow rate of the first reactive gas is greater than that during the first thick-film gallium nitride growth.

6. The method for preparing a semiconductor structure according to claim 5, characterized in that, During the first thick-film gallium nitride growth process, the gas flow rate of the first reactive gas is 1 sccm to 100 sccm, and the growth time of the first thick-film gallium nitride is 10 min to 5 h; during the second thick-film gallium nitride growth process, the gas flow rate of the first reactive gas is 50 sccm to 1000 sccm, and the growth time of the second thick-film gallium nitride is 1 min to 50 h.

7. The method for preparing a semiconductor structure according to claim 4, characterized in that, The doped thick-film gallium nitride layer includes a semi-insulating doped thick-film gallium nitride layer, and the doping gas includes at least one of carbon-containing gas, iron-containing gas, a mixture of carbon-containing gas and premixed gas, and a mixture of iron-containing gas and premixed gas.

8. The method for preparing a semiconductor structure according to claim 4, characterized in that, The doped thick-film gallium nitride layer includes an N-type doped thick-film gallium nitride layer, and the doping gas includes at least one of silicon-containing gas and a mixture of silicon-containing gas and premixed gas.

9. A semiconductor structure, characterized in that, The semiconductor structure is prepared by the semiconductor structure preparation method as described in any one of claims 1 to 8.

10. A method for preparing a self-supporting gallium nitride doped layer, characterized in that, include: The semiconductor structure is prepared using the method for preparing the semiconductor structure as described in any one of claims 1 to 8; The semiconductor structure is cooled to allow the doped thick-film gallium nitride layer to be automatically peeled off, resulting in a self-supporting doped gallium nitride layer.

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

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