Preparation method of epitaxial structure

Abstract

The invention discloses a preparation method of an epitaxial structure. The preparation method of the epitaxial structure comprises the following steps: forming a stripping layer on one side of a substrate; an epitaxial layer is formed on the side, away from the substrate, of the stripping layer, and the decomposition temperature of the stripping layer is smaller than that of the epitaxial layer; decomposing the stripping layer to enable the stripping layer to be completely separated from the epitaxial layer; or decomposing the stripping layer and reserving a part of thickness of the stripping layer on the epitaxial layer. According to the invention, the substrate can be stripped on the basis of damage as little as possible or no damage to the epitaxial layer.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for preparing an epitaxial structure. Background Art

[0002] Epitaxial structures, such as GaN-based optoelectronic devices and power devices, have important applications in the field of semiconductor technology. Currently, sapphire substrates are mainly used to manufacture GaN-based optoelectronic devices and power devices.

[0003] However, with the increase in integration and power, the disadvantage of poor thermal conductivity of sapphire substrates has become increasingly obvious, greatly restricting the further application of epitaxial structures. To solve this problem, the substrate can be peeled off by peeling technology. However, the existing peeling technology will damage the GaN epitaxial layer, increase the defect density of GaN, increase reverse leakage, and reduce the performance of the epitaxial structure. Summary of the invention

[0004] The invention provides an epitaxial structure and a preparation method thereof, so as to peel off a substrate without damaging an epitaxial layer.

[0005] According to one aspect of the present invention, a method for preparing an epitaxial structure is provided, the method for preparing the epitaxial structure comprising:

[0006] forming a peeling layer on one side of the substrate;

[0007] forming an epitaxial layer on a side of the peeling layer away from the substrate, wherein a decomposition temperature of the peeling layer is lower than a decomposition temperature of the epitaxial layer;

[0008] Decomposing the peeling layer so that the peeling layer is completely separated from the epitaxial layer;

[0009] Alternatively, the peeling layer is decomposed and a partial thickness of the peeling layer is retained on the epitaxial layer; and the peeling layer retained on a side of the epitaxial layer close to the substrate is removed.

[0010] Optionally, decomposing the peeling layer comprises:

[0011] The peeling layer is heated from a side of the peeling layer close to the substrate to decompose the peeling layer.

[0012] Optionally, heating the peeling layer from a side of the peeling layer close to the substrate comprises:

[0013] The release layer is irradiated with laser light from a side of the release layer close to the substrate.

[0014] Optionally, irradiating the peeling layer with laser light from a side of the peeling layer close to the substrate comprises:

[0015] The distance between the focal plane of the laser and the surface of the lift-off layer close to the epitaxial layer is controlled to be greater than or equal to 10 nanometers.

[0016] Optionally, the thickness of the peeling layer remaining after decomposing the peeling layer is less than or equal to 200 nanometers.

[0017] Optionally, removing the peeling layer retained on a side of the epitaxial layer close to the substrate comprises:

[0018] removing the retained release layer by chemical etching;

[0019] Alternatively, the retained peeling layer is removed by mechanical polishing;

[0020] Alternatively, the remaining release layer is removed by chemical mechanical polishing.

[0021] Optionally, the release layer includes a first surface opposite to the substrate and a second surface adjacent to the first surface, and the second surface of the release layer is a non-polar surface.

[0022] Optionally, forming a peeling layer on one side of the substrate includes:

[0023] A peeling layer is formed on one side of the substrate and matches the lattice constant of the epitaxial layer.

[0024] Optionally, forming a lift-off layer on one side of the substrate that matches the lattice constant of the epitaxial layer includes:

[0025] In is formed on one side of the substrate x Al 1-x N constitutes the peeling layer;

[0026] The step of forming an epitaxial layer on a side of the peeling layer away from the substrate comprises:

[0027] An epitaxial layer consisting of one or more combinations of AlN, GaN, AlGaN and InGaN is formed on the side of the peeling layer away from the substrate.

[0028] Optionally, before forming the peeling layer on one side of the substrate, the method further includes:

[0029] forming a transition layer on one side of the substrate;

[0030] The step of forming a peeling layer on one side of the substrate comprises:

[0031] The peeling layer is formed on a side of the transition layer away from the substrate.

[0032] Optionally, before forming the epitaxial layer on the side of the lift-off layer away from the substrate, the method further includes:

[0033] forming a buffer layer on a side of the peeling layer away from the substrate;

[0034] The step of forming an epitaxial layer on a side of the peeling layer away from the substrate comprises:

[0035] The epitaxial layer is formed on a side of the buffer layer away from the peeling layer.

[0036] The technical solution of the embodiment of the present invention adopts a method for preparing an epitaxial structure, comprising: forming a stripping layer on one side of a substrate; forming an epitaxial layer on a side of the stripping layer away from the substrate, wherein the decomposition temperature of the stripping layer is lower than the decomposition temperature of the epitaxial layer; decomposing the stripping layer so that the stripping layer is completely separated from the epitaxial layer; or decomposing the stripping layer and retaining a portion of the thickness of the stripping layer on the epitaxial layer. By setting the stripping layer with a decomposition temperature lower than the decomposition temperature of the epitaxial layer, when the stripping layer is decomposed to strip the substrate, thermal damage will not be caused to the epitaxial layer, so that the substrate can be stripped with little or no damage to the epitaxial layer.

[0037] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 A flow chart of a method for preparing an epitaxial structure provided in an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of a product structure formed by the main steps of a method for preparing an epitaxial structure provided by an embodiment of the present invention;

[0041] Figure 3 A schematic diagram of a product structure formed by the main steps of another method for preparing an epitaxial structure provided by an embodiment of the present invention;

[0042] Figure 4 A flow chart of another method for preparing an epitaxial structure provided in an embodiment of the present invention;

[0043] Figure 5 A schematic diagram of a product structure formed by the main steps of another method for preparing an epitaxial structure provided by an embodiment of the present invention;

[0044] Figure 6 A flow chart of another method for preparing an epitaxial structure provided in an embodiment of the present invention;

[0045] Figure 7 A schematic diagram of a product structure formed by the main steps of another method for preparing an epitaxial structure provided by an embodiment of the present invention;

[0046] Figure 8 A flow chart of another method for preparing an epitaxial structure provided in an embodiment of the present invention;

[0047] Fig. 9 A schematic diagram of a product structure formed by the main steps of another method for preparing an epitaxial structure provided by an embodiment of the present invention;

[0048] Fig.10 A flow chart of another method for preparing an epitaxial structure provided in an embodiment of the present invention;

[0049] Fig.11 A schematic diagram of a product structure formed by main steps of another method for preparing an epitaxial structure provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0050] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0051] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0052] Figure 1 A flowchart of a method for preparing an epitaxial structure provided in an embodiment of the present invention, Figure 2A schematic diagram of a product structure formed by the main steps of a method for preparing an epitaxial structure provided by an embodiment of the present invention, Figure 3 A schematic diagram of a product structure formed by the main steps of another method for preparing an epitaxial structure provided in an embodiment of the present invention, combined with Figures 1 to 3 The method for preparing the epitaxial structure comprises:

[0053] Step S110, forming a peeling layer on one side of the substrate;

[0054] Specifically, Figure 2 As shown, a substrate 11 is first provided; the substrate 11 can be a transparent substrate or a non-transparent substrate. To facilitate the subsequent peeling of the substrate 11, the substrate 11 is preferably a transparent substrate. Subsequently, a peeling layer 13 is formed on one side of the substrate 11. The peeling layer 13 is subsequently used to separate the substrate 11 from the epitaxial structure after peeling.

[0055] Step S120, forming an epitaxial layer on a side of the lift-off layer away from the substrate, wherein a decomposition temperature of the lift-off layer is lower than a decomposition temperature of the epitaxial layer;

[0056] Specifically, Figure 2 and Figure 3 As shown, after the peeling layer 13 is formed, the epitaxial layer 15 can be formed by growth or the like. The decomposition temperature of the peeling layer 13 and the decomposition temperature of the epitaxial layer 15 are both thermal decomposition temperatures. In this embodiment, the decomposition temperature of the peeling layer 13 is set to be lower than the decomposition temperature of the epitaxial layer 15, so that when the peeling layer 13 is subsequently thermally decomposed, the temperature of the peeling layer 13 is heated to a temperature greater than or equal to the decomposition temperature of the peeling layer and lower than the decomposition temperature of the epitaxial layer, thereby reducing thermal damage to the epitaxial layer 15.

[0057] Step S130, decomposing the stripping layer so that the stripping layer is completely separated from the epitaxial layer; or, decomposing the stripping layer and retaining a partial thickness of the stripping layer on the epitaxial layer; removing the stripping layer retained on the side of the epitaxial layer close to the substrate.

[0058] Specifically, Figure 2 and Figure 3 As shown, the peeling layer 13 can be decomposed by heating the peeling layer 13 to change the state of the peeling layer 13, so that the substrate is peeled off from the epitaxial layer structure. As described above, when the peeling layer is decomposed, the peeling layer 13 is heated to a preset temperature, which is greater than or equal to the decomposition temperature of the peeling layer 13 and less than the decomposition temperature of the epitaxial layer. When the peeling layer 13 is decomposed, it can be as follows Figure 2 The method shown in FIG. 1 is to completely separate the peeling layer from the epitaxial layer. In this method, the peeling layer 13 is not retained on the epitaxial layer, which can not only reduce the thermal damage to the epitaxial layer, but also eliminate the need to remove the peeling layer 13 later, resulting in fewer process steps. Alternatively, the method may be used as shown in FIG. Figure 3In the manner shown, when the peeling layer 13 is decomposed, a portion of the peeling layer 13 is retained on the epitaxial layer. Compared with completely separating the peeling layer 13 from the epitaxial layer 15, this manner can further avoid damage to the epitaxial layer 15 when the peeling layer 13 is decomposed, thereby achieving damage-free peeling. Figure 3 As shown, after the peeling layer is decomposed, a portion of the peeling layer will remain on the surface of the epitaxial layer 15, which is defined as the peeling layer retaining portion 131. The existence of the peeling layer retaining portion 131 will still affect the thermal conductivity of the epitaxial structure, thereby limiting the application of the epitaxial structure. Therefore, in this embodiment, the peeling layer 13 and the substrate 11 can be peeled off from the epitaxial layer by removing the peeling layer retaining portion 131, so that the epitaxial structure no longer retains the substrate and the peeling layer, thereby greatly improving the performance of the epitaxial structure.

[0059] The technical solution of this embodiment adopts a method for preparing an epitaxial structure, including: forming a peeling layer on one side of a substrate; forming an epitaxial layer on a side of the peeling layer away from the substrate, wherein the decomposition temperature of the peeling layer is lower than the decomposition temperature of the epitaxial layer; decomposing the peeling layer so that the peeling layer is completely separated from the epitaxial layer; or, decomposing the peeling layer and retaining a portion of the thickness of the peeling layer on the epitaxial layer. By setting the peeling layer with a decomposition temperature lower than the decomposition temperature of the epitaxial layer, when the peeling layer is decomposed to peel off the substrate, the thermal damage to the epitaxial layer is reduced, so that the substrate can be peeled off without damaging the epitaxial layer.

[0060] Optionally, decomposing the peeling layer so that the peeling layer is completely separated from the epitaxial layer may be completely decomposing the peeling layer. Decomposing the peeling layer and leaving a partial thickness of the peeling layer on the epitaxial layer may be partially decomposing the peeling layer.

[0061] Optionally, decomposing the peeling layer comprises:

[0062] The peeling layer is heated from a side of the peeling layer close to the substrate to decompose the peeling layer.

[0063] Specifically, in this embodiment, when the peeling layer is heated, the heating is started from the side of the peeling layer close to the substrate, in other words, the heating is started from the side of the peeling layer away from the epitaxial layer. Since the peeling layer has a certain thickness, by such a heating method, when the peeling layer is heated, the temperature transmitted to the epitaxial layer is less, so that the temperature of the epitaxial layer is lower than the decomposition temperature of the epitaxial layer, thereby further reducing the risk of thermal damage to the epitaxial layer.

[0064] Optionally, heating the peeling layer from a side of the peeling layer close to the substrate comprises:

[0065] The release layer is irradiated with laser light from a side of the release layer close to the substrate.

[0066] Specifically, the peeling layer is heated from the side close to the substrate by laser irradiation. Laser heating has the advantages of fast speed, etc., and can quickly heat the peeling layer to the decomposition temperature, and then quickly decompose the peeling layer, avoiding too long heating time so that more heat is transferred to the epitaxial layer, that is, it can further avoid the situation where the temperature of the epitaxial layer rises too much during the heating process. Preferably, by setting the substrate as a transparent substrate, the efficiency of laser irradiation can be further improved. In addition, in this embodiment, since the decomposition temperature of the peeling layer is lower than the decomposition temperature of the epitaxial layer, compared with the traditional laser irradiation epitaxial layer to peel off the substrate, a low-power laser can be used for the peeling layer in this embodiment, which can not only reduce costs, but also reduce thermal damage to the epitaxial layer. Preferably, the decomposition temperature of the peeling layer can be between 600°C and 800°C.

[0067] The method for preparing an epitaxial structure comprises decomposing a peeling layer and retaining a peeling layer of a partial thickness on the epitaxial layer; irradiating the peeling layer with a laser from a side of the peeling layer close to a substrate comprises:

[0068] The distance between the focal plane of the laser and the surface of the peeling layer close to the epitaxial layer is controlled to be greater than or equal to 10 nanometers.

[0069] Optionally, the thickness of the peeling layer is less than or equal to 1000 nanometers;

[0070] Specifically, in this embodiment, if the focal plane of the laser is too close to the surface of the peeling layer close to the epitaxial layer, heat is easily transferred to the epitaxial layer during the laser irradiation process, which may cause damage to the epitaxial layer. If the focal plane of the laser is too far from the surface of the peeling layer close to the epitaxial layer, the peeling layer retained in the end will be thicker, and it will take a long time to remove the retained peeling layer later.

[0071] Optionally, the thickness of the peeling layer retained after the peeling layer is decomposed is less than or equal to 200 nanometers. This arrangement ensures that the thickness of the retained peeling layer is not too thick, and it does not take a long time to remove the retained peeling layer later.

[0072] Optionally, removing the peeling layer retained on the side of the epitaxial layer close to the substrate includes:

[0073] The retained peeling layer is removed by chemical etching, or by mechanical polishing, or by chemical mechanical polishing. Of course, other methods can also be used to remove the retained peeling layer.

[0074] Optionally, the release layer includes a first surface opposite to the substrate and a second surface adjacent to the first surface, and the second surface of the release layer is a non-polar surface.

[0075] Specifically, the first surface of the peeling layer 13 can be understood as the bottom surface of the peeling layer 13, and the second surface of the peeling layer 13 can be understood as the side surface of the peeling layer 13. When the peeling layer 13 is chemically etched, since the second surface of the peeling layer 13 is set as a non-polar surface, it is convenient to etch the peeling layer from the side later without etching other film layers. In addition, since the peeling layer has been thermally damaged when the peeling layer is heated, the quality of the peeling layer is deteriorated, and it is easier to be etched and removed by chemical solutions, or easier to be removed by methods such as chemical mechanical polishing.

[0076] Optionally, forming a peeling layer on one side of the substrate includes:

[0077] A lift-off layer is formed on one side of the substrate, the lift-off layer matching the lattice constant of the epitaxial layer.

[0078] Specifically, in a structure without a stripping layer, due to the mismatch between the lattice constants of the substrate and the epitaxial layer, when the substrate is stripped by laser, the stress released by the substrate will damage the epitaxial layer. In this embodiment, due to the provision of a stripping layer, when the substrate is stripped by laser, although the substrate will also release stress, the released stress has little effect on the epitaxial layer, and thus the damage to the epitaxial layer is also small. In addition, when the stripping layer is corroded by a chemical solution, if the lattice constants of the stripping layer and the epitaxial layer do not match, the stripping layer and the epitaxial layer will cause a problem of stress release. When the stress of the stripping layer is released, the epitaxial layer may be damaged, thereby reducing the performance of the epitaxial structure. In this embodiment, the lattice constant of the stripping layer is matched with the lattice constant of the epitaxial layer. When the stripping layer is corroded, the problem of stress release of the stripping layer will be greatly suppressed, thereby further preventing damage to the epitaxial layer and ensuring that the performance of the epitaxial structure will not be reduced.

[0079] Optionally, forming a lift-off layer on one side of the substrate that matches the lattice constant of the epitaxial layer includes:

[0080] In is formed on one side of the substrate x Al 1-x N, wherein the value range of x is 0<x<1, preferably, the value range of x is 0.15 to 0.19;

[0081] Forming an epitaxial layer on a side of the lift-off layer away from the substrate includes:

[0082] An epitaxial layer consisting of one or more combinations of AlN, GaN, AlGaN and InGaN is formed on the side of the peeling layer away from the substrate.

[0083] Specifically, in this embodiment, the epitaxial layer can be a stacked structure of one or more of AlN, GaN, AlGaN and InGaN. x Al 1-xN, and when x is in the range of 0.15 to 0.19, the lattice constants of the peeling layer and the epitaxial layer are well matched. Therefore, when the peeling layer is corroded, the problem of stress release of the epitaxial layer can be greatly suppressed, and damage to the epitaxial layer can be further prevented, ensuring that the performance of the epitaxial structure will not be reduced. Of course, it should be noted that the peeling layer can also be made of other materials whose lattice constants match the lattice constants of the epitaxial layer. Lattice constant matching can be understood as the same lattice constants.

[0084] Optionally, Figure 4 A flowchart of another method for preparing an epitaxial structure provided in an embodiment of the present invention, Figure 5 A schematic diagram of a product structure formed by the main steps of another method for preparing an epitaxial structure provided in an embodiment of the present invention, combined with Figure 4 and Figure 5 In this embodiment, the method for preparing the epitaxial structure includes:

[0085] Step S210, forming a transition layer on one side of the substrate;

[0086] Specifically, the substrate 11 can be a combination of one or more of gallium nitride, aluminum gallium nitride, indium gallium nitride, aluminum indium gallium nitride, indium phosphide, gallium arsenide, silicon carbide, diamond, sapphire, germanium, silicon, or any other material capable of growing group III nitrides. The transition layer 12 can be a combination of one or more of AlN, GaN, AlGaN and InGaN. The transition layer 12 is used to enable the stripping layer 13 to grow smoothly, avoiding the problem of poor quality of the grown stripping layer due to the stripping layer growing directly on the substrate. In this embodiment, the transition layer 12 is grown directly on the substrate 11.

[0087] Step S220, forming a peeling layer on a side of the transition layer away from the substrate;

[0088] Specifically, forming the peeling layer on one side of the substrate includes forming the peeling layer 13 on the side of the transition layer away from the substrate. The peeling layer 13 is directly grown on the transition layer 12, and a peeling layer with good quality can be grown.

[0089] Step S120, forming an epitaxial layer on a side of the lift-off layer away from the substrate, wherein a decomposition temperature of the lift-off layer is lower than a decomposition temperature of the epitaxial layer;

[0090] Step S130, decomposing the stripping layer so that the stripping layer is completely separated from the epitaxial layer; or, decomposing the stripping layer and retaining a partial thickness of the stripping layer on the epitaxial layer; removing the stripping layer retained on the side of the epitaxial layer close to the substrate.

[0091] Optionally, Figure 6 A flowchart of another method for preparing an epitaxial structure provided in an embodiment of the present invention, Figure 7A schematic diagram of a product structure formed by the main steps of another method for preparing an epitaxial structure provided in an embodiment of the present invention, combined with Figure 6 and Figure 7 The method for preparing the epitaxial structure comprises:

[0092] Step S110, forming a peeling layer on one side of the substrate;

[0093] Step S310, forming a buffer layer on a side of the peeling layer away from the substrate;

[0094] Specifically, the material of the buffer layer 14 may be GaN, and the buffer layer 14 may improve the quality of the subsequently grown semiconductor material layer, thereby greatly improving the quality of the epitaxial structure. In this embodiment, the buffer layer is directly grown on the surface of the lift-off layer.

[0095] Step S320, forming an epitaxial layer on a side of the buffer layer away from the stripping layer;

[0096] Specifically, compared with the above-mentioned implementation manner, in this embodiment, the epitaxial layer is not grown directly on the corrosion layer, but is grown on the buffer layer, so that the quality of the epitaxial layer is better.

[0097] Step S130, decomposing the stripping layer so that the stripping layer is completely separated from the epitaxial layer; or, decomposing the stripping layer and retaining a partial thickness of the stripping layer on the epitaxial layer; removing the stripping layer retained on the side of the epitaxial layer close to the substrate.

[0098] Optionally, Figure 8 A flowchart of another method for preparing an epitaxial structure provided in an embodiment of the present invention, Fig. 9 A schematic diagram of a product structure formed by the main steps of another method for preparing an epitaxial structure provided in an embodiment of the present invention, referring to Figure 8 and Fig. 9 The method for preparing the epitaxial structure comprises:

[0099] Step S210, forming a transition layer on one side of the substrate;

[0100] Step S220, forming a peeling layer on a side of the transition layer away from the substrate;

[0101] Step S310, forming a buffer layer on a side of the peeling layer away from the substrate;

[0102] Step S320, forming an epitaxial layer on a side of the buffer layer away from the stripping layer;

[0103] Step S130, decomposing the stripping layer so that the stripping layer is completely separated from the epitaxial layer; or, decomposing the stripping layer and retaining a partial thickness of the stripping layer on the epitaxial layer; removing the stripping layer retained on the side of the epitaxial layer close to the substrate.

[0104] Specifically, in this embodiment, both a transition layer and a buffer layer are formed in the epitaxial structure, so that the quality of the grown peeling layer and epitaxial layer are good, thereby further reducing the risk of epitaxial layer damage when peeling off the substrate and improving the performance of the epitaxial structure.

[0105] Optionally, in the above embodiment, forming the corrosion layer on one side of the substrate includes: forming the corrosion layer on one side of the substrate using at least one of metal-organic chemical vapor deposition (Metal-organic Chemical Vapor Deposition, MOCVD) and molecular beam epitaxy (Molecular beam epitaxy, MBE); or forming the corrosion layer on one side of the substrate using a pulsed growth method.

[0106] Specifically, in this embodiment, the stripping layer can be grown by MOCVD, or by MBE, or by a mixture of MOCVD and MBE, for example, a certain thickness is first grown by MOCVD, and then the stripping layer of the remaining thickness is grown by MBE. Of course, a pulse growth method can also be used, such as during the entire growth process, NH3 is always introduced into the cavity, and the In source and Al source are sequentially introduced into the cavity in the form of pulses, the first pulse is the Al source introduced into the cavity, at which time the In source is not introduced into the cavity, and then the second pulse turns off the Al source and turns on the In source, and the cycle continues. It should be noted that the stripping layer can also be grown by other methods.

[0107] Optionally, Fig.10 A flowchart of another method for preparing an epitaxial structure provided in an embodiment of the present invention, Fig.11 A schematic diagram of a product structure formed by the main steps of another method for preparing an epitaxial structure provided in an embodiment of the present invention, referring to Fig.10 and Fig.11 The method for preparing the epitaxial structure comprises:

[0108] Step S110, forming a peeling layer on one side of the substrate, wherein the peeling layer includes a first surface opposite to the substrate and a second surface adjacent to the first surface, and the second surface of the peeling layer is a non-polar surface;

[0109] Step S120, forming an epitaxial layer on a side of the lift-off layer away from the substrate, wherein a decomposition temperature of the lift-off layer is lower than a decomposition temperature of the epitaxial layer;

[0110] After step S120, the method further includes:

[0111] Step S410, forming a channel layer on a side of the epitaxial layer away from the substrate;

[0112] Specifically, the channel layer 16 is directly grown on the epitaxial layer to obtain a better two-dimensional electron gas interface, reduce interface scattering, and improve mobility and two-dimensional electron gas concentration.

[0113] Step S420, forming a spacer layer on a side of the channel layer away from the epitaxial layer;

[0114] Specifically, the spacer layer 17 is directly grown on the channel layer 16 . The spacer layer 17 is an AlN spacer layer, which can raise the potential barrier to increase the confinement of the two-dimensional electron gas, while reducing alloy scattering and improving mobility.

[0115] Step S430, forming a barrier layer on a side of the spacer layer away from the channel layer;

[0116] Specifically, the barrier layer 18 is directly grown on the spacer layer 17, and the barrier layer can be AlGaN. The barrier layer 18 forms a heterojunction structure with the channel layer 16, so that the channel layer 16 can provide a channel for the movement of the two-dimensional electron gas. It should be noted that the barrier layer 18 is made of a different material from the stripping layer 13, so as to prevent the chemical solution from corroding the barrier layer 18 when the stripping layer 13 is corroded.

[0117] Step S440, forming a cap layer on a side of the barrier layer away from the spacer layer;

[0118] Specifically, the cap layer 19 can be used to reduce surface states, reduce surface leakage of subsequent devices, and inhibit current collapse, thereby improving device performance and reliability. It should be noted that in some optional implementations, the cap layer 19 may not be provided.

[0119] Step S130, decomposing the stripping layer so that the stripping layer is completely separated from the epitaxial layer; or, decomposing the stripping layer and retaining a partial thickness of the stripping layer on the epitaxial layer; removing the stripping layer retained on the side of the epitaxial layer close to the substrate.

[0120] The embodiment of the present invention further provides an epitaxial structure, which is made by the method for making an epitaxial structure provided by any embodiment of the present invention. The epitaxial structure provided by this embodiment has good performance because the epitaxial layer will not be lost when the substrate is peeled off.

[0121] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0122] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an epitaxial structure, characterized in that: The method for preparing the epitaxial structure comprises: forming a peeling layer on one side of the substrate; forming an epitaxial layer on a side of the peeling layer away from the substrate, wherein a decomposition temperature of the peeling layer is lower than a decomposition temperature of the epitaxial layer; Decomposing the peeling layer so that the peeling layer is completely separated from the epitaxial layer; Alternatively, the peeling layer is decomposed and a partial thickness of the peeling layer is retained on the epitaxial layer; and the peeling layer retained on a side of the epitaxial layer close to the substrate is removed.

2. The method for preparing an epitaxial structure according to claim 1, characterized in that: The decomposing the peeling layer comprises: The peeling layer is heated from a side of the peeling layer close to the substrate to decompose the peeling layer.

3. The method for preparing an epitaxial structure according to claim 2, characterized in that: The step of heating the peeling layer from a side of the peeling layer close to the substrate comprises: The release layer is irradiated with laser light from a side of the release layer close to the substrate.

4. The method for preparing an epitaxial structure according to claim 3, characterized in that: The step of irradiating the peeling layer with laser light from a side of the peeling layer close to the substrate comprises: The distance between the focal plane of the laser and the surface of the lift-off layer close to the epitaxial layer is controlled to be greater than or equal to 10 nanometers.

5. The method for preparing an epitaxial structure according to claim 1, characterized in that: The thickness of the peeling layer remaining after decomposing the peeling layer is less than or equal to 200 nanometers.

6. The method for preparing an epitaxial structure according to claim 1, characterized in that: The removing the peeling layer retained on a side of the epitaxial layer close to the substrate comprises: removing the retained release layer by chemical etching; Alternatively, the retained peeling layer is removed by mechanical polishing; Alternatively, the remaining release layer is removed by chemical mechanical polishing.

7. The method for preparing an epitaxial structure according to claim 1, characterized in that: The release layer includes a first surface opposite to the substrate and a second surface adjacent to the first surface, and the second surface of the release layer is a non-polar surface.

8. The method for preparing an epitaxial structure according to claim 1, characterized in that: The step of forming a peeling layer on one side of the substrate comprises: A peeling layer is formed on one side of the substrate and matches the lattice constant of the epitaxial layer.

9. The method for preparing an epitaxial structure according to claim 8, characterized in that: The step of forming a peeling layer on one side of the substrate and matching the lattice constant of the epitaxial layer comprises: In is formed on one side of the substrate x Al 1-x N constitutes the peeling layer; The step of forming an epitaxial layer on a side of the peeling layer away from the substrate comprises: An epitaxial layer consisting of one or more combinations of AlN, GaN, AlGaN and InGaN is formed on the side of the peeling layer away from the substrate.

10. The method for preparing an epitaxial structure according to claim 1, characterized in that: Before forming the peeling layer on one side of the substrate, the method further includes: forming a transition layer on one side of the substrate; The step of forming a peeling layer on one side of the substrate comprises: The peeling layer is formed on a side of the transition layer away from the substrate.

11. The method for preparing an epitaxial structure according to claim 1 or 10, characterized in that: Before forming an epitaxial layer on a side of the peeling layer away from the substrate, the method further comprises: forming a buffer layer on a side of the peeling layer away from the substrate; The step of forming an epitaxial layer on a side of the peeling layer away from the substrate comprises: The epitaxial layer is formed on a side of the buffer layer away from the peeling layer.

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