Silicon carbide-based composite substrate, method for manufacturing the same, and functional device

Abstract

The application provides a silicon carbide-based composite substrate, a preparation method thereof and a functional device, and relates to the technical field of semiconductors. The preparation method of the silicon carbide-based composite substrate comprises the following steps: providing a silicon carbide substrate and a first donor substrate; the first donor substrate comprises at least a monocrystalline silicon film layer and a first sacrificial layer located on one side of the monocrystalline silicon film layer in the thickness direction; bonding the silicon carbide substrate and the first donor substrate in a manner that the silicon carbide substrate and the monocrystalline silicon film layer face each other; and removing the first sacrificial layer to form an oxide layer on the bonding side of the silicon carbide substrate. By completely oxidizing at least the monocrystalline silicon film layer, the oxide layer is formed on the bonding side of the silicon carbide substrate. Since the oxidation rate of the monocrystalline silicon film layer is higher, the preparation efficiency of the oxide layer on the silicon carbide substrate is improved, and the preparation efficiency of the silicon carbide-based composite substrate of the application is further improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a silicon carbide-based composite substrate, its preparation method, and functional devices. Background Technology

[0002] Silicon carbide, as a representative material in third-generation semiconductors, possesses excellent properties such as wide bandgap, high breakdown electric field, high thermal conductivity, and high temperature resistance. It has become an ideal material for manufacturing high-voltage, high-temperature, and high-frequency power devices such as metal-oxide-semiconductor transistors (MOSFETs), power diodes, power triodes, and thyristors.

[0003] Currently, when using silicon carbide as a substrate to manufacture silicon carbide power devices, an oxide layer needs to be prepared on the silicon carbide substrate to perform functions such as surface passivation, protection, field intensity regulation, and electrical isolation.

[0004] However, the slow oxidation rate and long preparation cycle of silicon carbide affect the substrate preparation efficiency. Summary of the Invention

[0005] This application provides a silicon carbide-based composite substrate, its preparation method, and a functional device. By transferring a single-crystal silicon thin film layer onto a silicon carbide substrate and at least completely oxidizing the single-crystal silicon thin film layer, an oxide layer is formed on one side of the silicon carbide substrate. Since the oxidation rate of the single-crystal silicon thin film layer is higher, the preparation efficiency of the oxide layer on the silicon carbide substrate can be improved, thereby improving the preparation efficiency of the silicon carbide-based composite substrate.

[0006] In a first aspect, this application provides a method for preparing a silicon carbide-based composite substrate, comprising:

[0007] A silicon carbide substrate and a first donor substrate are provided; the first donor substrate includes at least a monocrystalline silicon thin film layer and a first sacrificial layer located on one side of the thickness direction of the monocrystalline silicon thin film layer;

[0008] The silicon carbide substrate and the first donor substrate are bonded together with the silicon carbide substrate and the single-crystal silicon thin film layer facing each other.

[0009] Remove the first sacrificial layer and form an oxide layer on the bonding side of the silicon carbide substrate.

[0010] In one possible implementation, the entire single-crystal silicon thin film layer is oxidized before bonding the silicon carbide substrate and the first donor substrate.

[0011] Alternatively, before bonding the silicon carbide substrate and the first donor substrate, a portion of the single-crystal silicon thin film layer is oxidized from the bonding side, and the remaining portion of the single-crystal silicon thin film layer is oxidized after removing the first sacrificial layer.

[0012] Alternatively, after removing the first sacrificial layer, all of the monocrystalline silicon thin film layers can be oxidized.

[0013] In one possible implementation, forming an oxide layer on the bonding side of the silicon carbide substrate includes:

[0014] Oxidation treatment of all of the said single-crystal silicon thin film layers; and,

[0015] The surface of the silicon carbide substrate is bonded to the first donor substrate by oxidation treatment.

[0016] In one possible implementation, before bonding the silicon carbide substrate and the first donor substrate, the surface of the silicon carbide substrate bonded to the first donor substrate is oxidized.

[0017] Alternatively, after removing the first sacrificial layer, the surface of the silicon carbide substrate bonded to the first donor substrate is oxidized.

[0018] In one possible implementation, providing the first donor substrate includes:

[0019] Provide a first silicon substrate;

[0020] A first separation layer is formed within the first silicon substrate by ion implantation; a single-crystal silicon thin film layer and a first sacrificial layer are formed on both sides of the first separation layer, respectively.

[0021] The removal of the first sacrificial layer includes:

[0022] The first donor substrate is annealed.

[0023] In one possible implementation, when all or part of the single-crystal silicon thin film layer is oxidized before bonding the silicon carbide substrate and the first donor substrate, providing the first donor substrate includes:

[0024] A first silicon substrate is provided, and a first separation layer is pre-set within the first silicon substrate, the first separation layer defining the monocrystalline silicon thin film layer and the first sacrificial layer;

[0025] Oxidation treatment of all or part of the single-crystal silicon thin film layer;

[0026] The monocrystalline silicon thin film layer after self-oxidation treatment is ion implanted laterally into the first separation layer of the first silicon substrate.

[0027] In one possible implementation, providing the first donor substrate includes:

[0028] Provide a second silicon substrate;

[0029] An intermediate layer is formed within the second silicon substrate by an oxidation process; a single-crystal silicon thin film layer and the first sacrificial layer are formed on both sides of the intermediate layer, respectively.

[0030] The removal of the first sacrificial layer includes:

[0031] Remove only the first sacrificial layer from the side of the second silicon substrate away from the silicon carbide substrate, or remove the first sacrificial layer and at least part of the intermediate layer.

[0032] In one possible implementation, after forming the oxide layer on the bonding side of the silicon carbide substrate, the method further includes:

[0033] A second donor substrate is provided; the second donor substrate includes at least a functional layer and a second sacrificial layer located on one side of the functional layer thickness direction;

[0034] The oxide layer and the second donor substrate are bonded together with the functional layer and the oxide layer facing each other.

[0035] Remove the second sacrificial layer.

[0036] In one possible implementation, the functional layer is made of at least one of lithium niobate, lithium tantalate, silicon carbide, silicon, gallium nitride, and gallium arsenide.

[0037] Secondly, this application provides a silicon carbide-based composite substrate, which is prepared by the preparation method described above;

[0038] The silicon carbide-based composite substrate includes:

[0039] Silicon carbide substrate;

[0040] An oxide layer is located on one side of the silicon carbide substrate layer; the oxide layer is formed from at least a single-crystal silicon thin film layer by an oxidation process.

[0041] Thirdly, this application provides a functional device, including the silicon carbide-based composite substrate as described above.

[0042] The silicon carbide-based composite substrate, its preparation method, and functional device provided in this application transfer a single-crystal silicon thin film layer onto a silicon carbide substrate through a first donor substrate. At least the single-crystal silicon thin film layer is completely oxidized to form an oxide layer on the bonding side of the silicon carbide substrate. Since the oxidation rate of the single-crystal silicon thin film layer is higher, the preparation efficiency of the oxide layer on the silicon carbide substrate can be improved, thereby improving the preparation efficiency of the silicon carbide-based composite substrate of this application. Attached Figure Description

[0043] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0044] Figure 1 A flowchart illustrating the preparation method of a silicon carbide-based composite substrate provided in some embodiments of this application;

[0045] Figure 2 This is a flowchart illustrating the method for preparing a silicon carbide-based composite substrate as provided in Embodiment 1 of this application.

[0046] Figure 3 This is a flowchart illustrating the preparation method of the silicon carbide-based composite substrate provided in Embodiment 2 of this application;

[0047] Figure 4 This is a flowchart illustrating the preparation method of the silicon carbide-based composite substrate provided in Embodiment 3 of this application;

[0048] Figure 5 This is a flowchart of the method for preparing a silicon carbide-based composite substrate provided in Embodiment 4 of this application;

[0049] Figure 6 This is a flowchart illustrating the method for preparing a silicon carbide-based composite substrate as provided in Embodiment 5 of this application;

[0050] Figure 7 This is a flowchart illustrating the method for preparing a silicon carbide-based composite substrate as provided in Embodiment Six of this application;

[0051] Figure 8 This is a flowchart illustrating the method for preparing a silicon carbide-based composite substrate as provided in Embodiment 7 of this application;

[0052] Figure 9 This is a flowchart illustrating the method for preparing a silicon carbide-based composite substrate as provided in Embodiment 8 of this application.

[0053] Figure 10 This is a flowchart illustrating the preparation method of the silicon carbide-based composite substrate provided in Embodiment 9 of this application;

[0054] Figure 11 This is a flowchart illustrating the preparation method of the silicon carbide-based composite substrate provided in Embodiment 10 of this application;

[0055] Figure 12 This is a flowchart illustrating the preparation method of the silicon carbide-based composite substrate provided in Example 11 of this application.

[0056] Explanation of reference numerals in the attached figures:

[0057] 100', Silicon carbide substrate; 100', Silicon carbide substrate layer;

[0058] 201, First silicon substrate; 202, Second silicon substrate; 210, Single-crystal silicon thin film layer; 220, First sacrificial layer; 230, First separation layer; 240, Intermediate layer; 250, Second donor substrate; 251, Functional layer; 252, Second sacrificial layer; 253, Second separation layer;

[0059] 310, First oxide layer; 320, Second oxide layer; 330, Third oxide layer; 340, Fourth oxide layer.

[0060] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0061] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0062] Currently, when using silicon carbide as a substrate to manufacture silicon carbide power devices, an oxide layer needs to be prepared on the silicon carbide substrate to perform functions such as surface passivation, protection, field intensity regulation, and electrical isolation.

[0063] However, the slow oxidation rate and long preparation cycle of silicon carbide affect the substrate preparation efficiency.

[0064] This application provides a silicon carbide-based composite substrate, its preparation method, and a functional device. A single-crystal silicon thin film layer is transferred onto a silicon carbide substrate through a first donor substrate. The single-crystal silicon thin film layer is at least completely oxidized to form an oxide layer on the bonding side of the silicon carbide substrate. Since the oxidation rate of the single-crystal silicon thin film layer is higher, the preparation efficiency of the oxide layer on the silicon carbide substrate can be improved, thereby improving the preparation efficiency of the silicon carbide-based composite substrate in this application embodiment.

[0065] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0066] Firstly, this application provides a method for preparing a silicon carbide-based composite substrate, see [link to relevant documentation]. Figure 1As shown, the preparation method includes the following steps:

[0067] A silicon carbide substrate and a first donor substrate are provided; the first donor substrate includes at least a monocrystalline silicon thin film layer and a first sacrificial layer located on one side of the thickness direction of the monocrystalline silicon thin film layer. In this embodiment, the first donor substrate may include only the monocrystalline silicon thin film layer and the first sacrificial layer, or it may include other layers besides the monocrystalline silicon thin film layer and the first sacrificial layer, without particular limitation.

[0068] The silicon carbide substrate and the first donor substrate are bonded together with the silicon carbide substrate and the single-crystal silicon thin film layer facing each other. In this embodiment, the first donor substrate is stacked on the silicon carbide substrate through the bonding between the silicon carbide substrate and the single-crystal silicon thin film layer.

[0069] The first sacrificial layer is removed, and an oxide layer is formed on the bonding side of the silicon carbide substrate. In this embodiment, the first sacrificial layer is removed, and a single-crystal silicon thin film layer is retained on the silicon carbide substrate. By at least oxidizing the single-crystal silicon thin film layer, an oxide layer can be formed on the bonding side of the silicon carbide substrate.

[0070] It is understandable that when using silicon carbide as a substrate to manufacture silicon carbide power devices, an oxide layer needs to be prepared on the silicon carbide substrate. The oxide layer serves functions such as surface passivation, protection, field intensity regulation, and electrical isolation. Conventionally, a silicon dioxide layer is formed on the silicon carbide substrate through thermal oxidation, and this silicon dioxide layer forms the oxide layer. The preparation method of this application is based on the fact that the oxide layer on the silicon carbide substrate is a silicon dioxide layer, and the direct product of silicon oxidation is silicon dioxide. Furthermore, silicon has a higher oxidation rate than silicon carbide. Therefore, the matching degree of forming an oxide layer on silicon carbide with silicon assistance is higher, and the preparation efficiency is higher.

[0071] Furthermore, due to its lattice characteristics, monocrystalline silicon allows the oxidation rate at different locations to remain relatively consistent during oxidation treatment, without significant differences, resulting in higher oxidation uniformity.

[0072] The preparation method of this application embodiment involves transferring a single-crystal silicon thin film layer onto a silicon carbide substrate using a first donor substrate. Since the oxidation rate of the single-crystal silicon thin film layer is higher, it is easier to oxidize the single-crystal silicon thin film layer when the silicon carbide substrate containing the single-crystal silicon thin film layer is oxidized. This makes it easier to form an oxide layer on the silicon carbide substrate, thereby improving the preparation efficiency of the oxide layer on the silicon carbide substrate and thus improving the preparation efficiency of the silicon carbide-based composite substrate of this application embodiment.

[0073] In this application, it is understood that the timing of oxidizing the single-crystal silicon thin film layer to form an oxide layer on the bonding side of the silicon carbide substrate is not particularly limited, as long as an oxide layer can eventually be formed on the silicon carbide substrate. For example, the oxidation can occur before the silicon carbide substrate and the first donor substrate are bonded, or after the first sacrificial layer is removed, or partly before the silicon carbide substrate and the first donor substrate are bonded and the remainder occurs after the first sacrificial layer is removed.

[0074] Specifically, in some embodiments of this application, all single-crystal silicon thin film layers are oxidized before bonding the silicon carbide substrate and the first donor substrate; or, before bonding the silicon carbide substrate and the first donor substrate, a portion of the single-crystal silicon thin film layer is oxidized from the bonding side, and the remaining portion of the single-crystal silicon thin film layer is oxidized after removing the first sacrificial layer; or, after removing the first sacrificial layer, all single-crystal silicon thin film layers are oxidized.

[0075] For example, the thickness of the monocrystalline silicon thin film layer is 20nm-2μm. The thickness of the monocrystalline silicon thin film layer ranges from nanometer to micrometer, which can realize the preparation of silicon dioxide layers with a wide range of thicknesses. Specifically, the thickness of the monocrystalline silicon thin film layer can be selected as 20nm, 40nm, 60nm, 80nm, 100nm, 200nm, 500nm, 750nm, 900nm, 1μm, 1.2μm, 1.5μm, 1.7μm, 1.9μm or 2μm.

[0076] As another example, before bonding the silicon carbide substrate and the first donor substrate, when partially oxidizing the single-crystal silicon thin film layer, the partial oxidation thickness of the single-crystal silicon thin film layer is 10nm-30nm. Specifically, the partial oxidation thickness of the single-crystal silicon thin film layer can be selected as 10nm, 12nm, 15nm, 18nm, 20nm, 21nm, 23nm, 27nm, 29nm or 30nm.

[0077] As another example, whenever the monocrystalline silicon thin film layer is oxidized, the oxidation temperature for oxidizing the monocrystalline silicon thin film layer is 700℃-1000℃.

[0078] It is worth mentioning that by oxidizing all or part of the monocrystalline silicon thin film layer before bonding, direct bonding between amorphous silicon dioxide and silicon carbide can be achieved during bonding without the problem of lattice mismatch.

[0079] In some embodiments of this application, removing the first sacrificial layer and forming an oxide layer on the bonding side of the silicon carbide substrate specifically includes the following steps:

[0080] Remove the first sacrificial layer. In this embodiment, by removing the first sacrificial layer, the single-crystal silicon thin film layer on the first donor substrate can be transferred to the silicon carbide substrate, thereby realizing the fabrication of a single-crystal silicon thin film layer on the silicon carbide substrate.

[0081] The entire monocrystalline silicon thin film layer is oxidized. In this embodiment, if only part of the monocrystalline silicon thin film layer was oxidized, or if the monocrystalline silicon thin film layer was not oxidized, before bonding the silicon carbide substrate and the first donor substrate, then after removing the first sacrificial layer, the oxidation treatment of the entire monocrystalline silicon thin film layer is completed, so that the entire monocrystalline silicon thin film layer forms a silicon dioxide layer. It is worth mentioning that if the monocrystalline silicon thin film layer has already been completely oxidized before bonding the silicon carbide substrate and the first donor substrate, then this step is unnecessary.

[0082] For example, if the monocrystalline silicon thin film layer is not oxidized before bonding the first donor substrate and the silicon carbide substrate, then the bonding is completed with the monocrystalline silicon thin film layer and the silicon carbide substrate facing each other. After removing the first sacrificial layer, the entire monocrystalline silicon thin film layer is oxidized to form a silicon dioxide layer, thereby forming an oxide layer on one side of the silicon carbide substrate.

[0083] In another example, before bonding the first donor substrate and the silicon carbide substrate, a portion of the monocrystalline silicon thin film layer is oxidized, forming a silicon dioxide layer on the side of the monocrystalline silicon thin film layer away from the first sacrificial layer. During bonding, the silicon dioxide layer and the silicon carbide substrate face each other. After removing the first sacrificial layer, the monocrystalline silicon thin film layer is oxidized again, allowing the remaining unoxidized portion to be oxidized, thus forming a silicon dioxide layer on the entire monocrystalline silicon thin film layer. This achieves the formation of an oxide layer on one side of the silicon carbide substrate.

[0084] As another example, if the entire monocrystalline silicon thin film layer is oxidized before bonding the first donor substrate and the silicon carbide substrate, the entire monocrystalline silicon thin film layer forms a silicon dioxide layer. During bonding, the silicon dioxide layer and the silicon carbide substrate face each other. Afterward, the first sacrificial layer is removed, and an oxide layer can be formed on one side of the silicon carbide substrate.

[0085] In this embodiment, an oxide layer is formed on the bonding side of the silicon carbide substrate. In addition to including the entire single-crystal silicon thin film layer that has undergone oxidation treatment, it may also include: the surface of the silicon carbide substrate bonded to the first donor substrate that has undergone oxidation treatment.

[0086] In this application, it is understood that the timing of oxidizing the surface of the silicon carbide substrate bonded to the first donor substrate is not particularly limited, as long as the surface of the bonding side of the silicon carbide substrate can be oxidized to form an oxide. For example, the oxidation can occur before the silicon carbide substrate and the first donor substrate are bonded, or after the first sacrificial layer is removed.

[0087] For example, whenever the surface of the silicon carbide substrate bonded to the first donor substrate is oxidized, the oxidation temperature for oxidizing the silicon carbide substrate is 1000℃-1300℃. The oxidation thickness of the silicon carbide substrate is 5nm-10nm, specifically, the oxidation thickness of the silicon carbide substrate can be selected as 5nm, 6nm, 7nm, 8nm, 9nm or 10nm.

[0088] Therefore, in this embodiment, all the single-crystal silicon thin film layers are oxidized, and the surface of the silicon carbide substrate used for bonding the single-crystal silicon thin film layers is oxidized, so that a silicon dioxide layer can also be formed on the surface of the silicon carbide substrate used for bonding the single-crystal silicon thin film layers. The oxidation products of the single-crystal silicon thin film layers and the oxidation products of the surface of the silicon carbide substrate used for bonding the single-crystal silicon thin film layers together form a silicon dioxide layer, i.e. an oxide layer, forming an oxide layer composite structure on the silicon carbide substrate.

[0089] It is worth mentioning that by further oxidizing the silicon carbide substrate, the bonding interface between the silicon carbide substrate and the monocrystalline silicon thin film layer after overall oxidation becomes a silicon dioxide-silicon dioxide bonding interface, which improves the quality of the bonding interface and results in higher bonding strength. Furthermore, because the oxidation thickness of the silicon carbide substrate is relatively small, it does not lead to excessively high interface state density.

[0090] It is worth mentioning that, based on the oxidation timing of the single-crystal silicon thin film layer and the oxidation timing of the surface of the silicon carbide substrate bonded to the first donor substrate in this embodiment, various oxidation schemes can be obtained. Specifically:

[0091] For example, no oxidation treatment is performed on the monocrystalline silicon thin film layer before bonding the first donor substrate and the silicon carbide substrate, or a portion of the monocrystalline silicon thin film layer is oxidized before bonding the first donor substrate and the silicon carbide substrate. After bonding the first donor substrate and the silicon carbide substrate and removing the first sacrificial layer, oxidation treatment begins from the side of the monocrystalline silicon thin film layer away from the silicon carbide substrate. First, a silicon dioxide layer is formed on the entire monocrystalline silicon thin film layer, and then a silicon dioxide layer is formed on the surface of the bonding side of the silicon carbide substrate.

[0092] It is worth mentioning that, due to the regularity of the grains and the uniformity of the lattice of monocrystalline silicon, the oxidation rate of the monocrystalline silicon thin film is relatively consistent from the direction of the monocrystalline silicon thin film towards the silicon carbide substrate during the oxidation treatment. This high uniformity allows all positions of the monocrystalline silicon thin film to be oxidized to the bonding interface with the silicon carbide substrate almost simultaneously, thus maintaining a relatively consistent oxidation rate on the silicon carbide substrate. This optimizes the grain state of the bonding interface between the monocrystalline silicon thin film and the silicon carbide substrate, improving the bonding effect.

[0093] For example, before bonding the first donor substrate and the silicon carbide substrate, the entire monocrystalline silicon thin film layer is subjected to complete oxidation. After bonding the first donor substrate and the silicon carbide substrate and removing the first sacrificial layer, only the surface of the silicon carbide substrate is oxidized. By oxidizing the monocrystalline silicon thin film layer and the silicon carbide substrate separately, the oxidation transition between the monocrystalline silicon thin film layer and the silicon carbide substrate can be avoided, thereby avoiding the problem of poor grain state at the bonding interface caused by inconsistent oxidation rates at different locations.

[0094] For example, before bonding the silicon carbide substrate to the first donor substrate, the bonding surface of the silicon carbide substrate is oxidized, and a portion of the single-crystal silicon thin film layer is oxidized. After the first donor substrate and the silicon carbide substrate are bonded and the first sacrificial layer is removed, the remaining unoxidized portion of the single-crystal silicon thin film layer is oxidized starting from the side of the single-crystal silicon thin film layer facing away from the silicon carbide substrate. When the silicon carbide substrate and the first donor substrate are bonded, bonding can be completed with the silicon dioxide layers facing each other, which can improve the bonding effect between the silicon carbide substrate and the first donor substrate.

[0095] For example, before bonding the silicon carbide substrate to the first donor substrate, the bonding surface of the silicon carbide substrate and the entire single-crystal silicon thin film layer are oxidized. After the first donor substrate and the silicon carbide substrate are bonded and the first sacrificial layer is removed, no oxidation treatment is required. When bonding the silicon carbide substrate to the first donor substrate, bonding can also be completed with the silicon dioxide layers facing each other, which can improve the bonding effect between the silicon carbide substrate and the first donor substrate.

[0096] For example, before bonding the first donor substrate and the silicon carbide substrate, no oxidation treatment is performed on the monocrystalline silicon thin film layer. Instead, the bonding surface of the silicon carbide substrate is oxidized before bonding with the first donor substrate. During bonding, the silicon dioxide layer and the monocrystalline silicon thin film layer are bonded facing each other, enabling direct bonding between amorphous silicon dioxide and monocrystalline silicon without lattice mismatch. After removing the first sacrificial layer, the entire monocrystalline silicon thin film layer is oxidized to form a silicon dioxide layer.

[0097] It is understood that by oxidizing the bonding surface of the silicon carbide substrate before bonding it to the first donor substrate, the bonding surface of the silicon carbide substrate is directly exposed, making it easier for the bonding surface of the silicon carbide substrate to be oxidized during the oxidation process, thereby improving the preparation efficiency of the silicon carbide-based composite substrate in the embodiments of this application.

[0098] In some embodiments of this application, providing a first donor substrate includes:

[0099] A first silicon substrate is provided. In this embodiment, the first silicon substrate is a monocrystalline silicon substrate.

[0100] A first separation layer is formed within a first silicon substrate by ion implantation. A monocrystalline silicon thin film layer and a first sacrificial layer are formed on both sides of the first separation layer. Specifically, the monocrystalline silicon thin film layer is formed on the side of the first separation layer closest to the ion implantation direction, and the first sacrificial layer is formed on the side of the first separation layer furthest from the ion implantation direction. In this embodiment, vaporizable ions are implanted into the first silicon substrate, thereby forming the first separation layer inside the first silicon substrate, with a monocrystalline silicon thin film layer and a first sacrificial layer formed on both sides of the first separation layer. Exemplarily, the implanted ions are one or more of hydrogen ions and helium ions. The ion implantation dose is 1 × 10⁻⁶. 16 -1×10 17 ions / cm 2 The ion implantation energy ranges from 1 keV to 250 keV.

[0101] Furthermore, in this embodiment, by annealing the first donor substrate, the implanted ions in the first separation layer are vaporized and interconnected, thereby allowing the first sacrificial layer to be peeled off and removed, thus transferring the single-crystal silicon thin film layer onto the silicon carbide substrate. Exemplarily, the annealing temperature for the first donor substrate is 200℃-400℃; the annealing time is 1h-6h; and the annealing atmosphere is air or nitrogen. In some embodiments of this application, after removing the first sacrificial layer from the first silicon substrate, the exposed surface of the single-crystal silicon thin film layer is polished to remove any remaining first separation layer, thereby reducing surface defects on the exposed surface of the single-crystal silicon thin film layer.

[0102] Furthermore, in this embodiment, when all or part of the single-crystal silicon thin film layer is oxidized before bonding the silicon carbide substrate and the first donor substrate, providing the first donor substrate includes: providing a first silicon substrate, pre-setting a first separation layer in the first silicon substrate, defining the single-crystal silicon thin film layer and the first sacrificial layer through the first separation layer; oxidizing all or part of the single-crystal silicon thin film layer; and performing ion implantation from the oxidized single-crystal silicon thin film layer to the first separation layer of the first silicon substrate. Thus, the oxidation treatment of the single-crystal silicon thin film layer before bonding occurs before ion implantation, avoiding the problems of high-temperature oxidation (700℃-1000℃, far exceeding the annealing temperature of 200℃-400℃ for stripping and removing the first sacrificial layer) during ion implantation followed by oxidation, which would cause the first donor substrate to directly peel off the first sacrificial layer at the first separation layer after ion implantation before bonding, and the thinner oxidized single-crystal silicon thin film layer to fragment without support.

[0103] In some embodiments of this application, the method of providing the first donor substrate may also be:

[0104] A second silicon substrate is provided. In this embodiment, the second silicon substrate is a monocrystalline silicon substrate.

[0105] An intermediate layer is formed within a second silicon substrate through an oxidation process. A monocrystalline silicon thin film layer and a first sacrificial layer are formed on both sides of the intermediate layer, respectively. In this embodiment, an oxygen implantation process and an annealing process can be used to oxidize the interior of the second silicon substrate to form an intermediate layer, which is a silicon dioxide layer. A monocrystalline silicon thin film layer and a first sacrificial layer can then be formed on both sides of the intermediate layer. Specifically, the monocrystalline silicon thin film layer is formed on the side of the intermediate layer closer to the oxygen implantation direction, and the first sacrificial layer is formed on the side of the intermediate layer away from the oxygen implantation direction. It is understood that the first donor substrate prepared by the above method in this application embodiment is also called an SOI substrate (Silicon-On-Insulator). It can be prepared by oneself or purchased commercially.

[0106] For example, after the first donor substrate is bonded to the silicon carbide substrate, the first sacrificial layer is removed by grinding, and the single-crystal silicon thin film layer and the intermediate layer are transferred onto the silicon carbide substrate.

[0107] In another exemplary manner, after the first donor substrate is bonded to the silicon carbide substrate, the first sacrificial layer is removed by grinding, and the intermediate layer is removed by etching with hydrofluoric acid (HF) or BOE (buffered oxide etchant, the main component of which is HF), thereby transferring the single-crystal silicon thin film layer onto the silicon carbide substrate.

[0108] It is worth mentioning that when a thicker oxide layer needs to be prepared on a silicon carbide substrate, after the first donor substrate is bonded to the silicon carbide substrate, only the first sacrificial layer can be removed, or the first sacrificial layer and part of the intermediate layer can be removed, so that at least part of the intermediate layer can be transferred to the silicon carbide substrate together with the single crystal silicon thin film layer. Since the intermediate layer is a silicon dioxide layer, the intermediate layer, the single crystal silicon thin film layer after overall oxidation treatment and the silicon dioxide layer oxidized on the bonding surface of the silicon carbide substrate can jointly form an oxide layer, thereby improving the preparation efficiency of a thicker oxide layer on the silicon carbide substrate.

[0109] In some embodiments of this application, after forming an oxide layer on the bonding side of the silicon carbide substrate, the preparation method of this application embodiment further includes:

[0110] A second donor substrate is provided, comprising at least a functional layer and a second sacrificial layer located on one side of the functional layer thickness direction. In this embodiment, the material of the second donor substrate is not limited and may be at least one of lithium niobate, lithium tantalate, silicon carbide, silicon, gallium nitride, and gallium arsenide. Correspondingly, the material of the functional layer is at least one of lithium niobate, lithium tantalate, silicon carbide, silicon, gallium nitride, and gallium arsenide.

[0111] The oxide layer and the second donor substrate are bonded together with the functional layer and the oxide layer facing each other. In this embodiment, the second donor substrate is stacked on the side of the oxide layer away from the silicon carbide substrate by a bonding process.

[0112] Remove the second sacrificial layer.

[0113] For example, after the silicon carbide substrate and the second donor substrate are bonded, the second sacrificial layer is removed by grinding from the side of the second donor substrate away from the silicon carbide substrate, thereby transferring the functional layer onto the silicon carbide substrate.

[0114] In another exemplary embodiment, the second donor substrate is an ion-implanted sheet that has undergone ion implantation. Ion implantation allows a second separation layer to be formed within the second donor substrate, with a functional layer and a second sacrificial layer formed on opposite sides of the second separation layer. Specifically, the functional layer is formed on the side of the second separation layer closest to the ion implantation direction, and the second sacrificial layer is formed on the side of the second separation layer furthest from the ion implantation direction. The implanted ions, ion implantation dose, and ion implantation energy are not limited; for example, the implanted ions can be one or more of hydrogen ions, helium ions, nitrogen ions, oxygen ions, or argon ions; the ion implantation dose is 1 × 10⁻⁶. 16 -3×10 17 ions / cm 2The ion implantation energy is 30 keV-5 MeV. Further, after bonding the oxide layer and the second donor substrate, the second donor substrate is annealed to vaporize and connect the implanted ions in the second separation layer, thereby allowing the second sacrificial layer to be peeled off and transferred to the silicon carbide substrate. Exemplarily, the annealing temperature for the second donor substrate is 100℃-600℃; the annealing time is 1h-24h; and the annealing atmosphere is air or nitrogen. In some embodiments of this application, after removing the second sacrificial layer from the second donor substrate, the exposed surface of the functional layer is polished to remove any remaining second separation layer, thereby reducing surface defects on the exposed surface of the functional layer.

[0115] Secondly, embodiments of this application provide a silicon carbide-based composite substrate, prepared by the above-described preparation method. Therefore, it possesses the corresponding technical effects and advantages described above.

[0116] The silicon carbide-based composite substrate of this application embodiment includes a silicon carbide substrate layer and an oxide layer located on the silicon carbide substrate layer, with the oxide layer situated on one side of the silicon carbide substrate layer in the thickness direction. The oxide layer is formed at least by oxidation of a single-crystal silicon thin film layer. Exemplarily, the oxide layer is formed solely by oxidation of a single-crystal silicon thin film layer. Yet another example, the oxide layer comprises two parts: one part is formed by oxidation of a single-crystal silicon thin film layer, and the other part is formed by oxidation of the surface of the silicon carbide substrate bonded to the first donor substrate. Still another example, the oxide layer comprises two parts: one part is at least a portion of the intermediate layer of the first donor substrate, and the other part is formed by oxidation of a single-crystal silicon thin film layer. Yet another example, the oxide layer comprises three parts: one part is at least a portion of the intermediate layer of the first donor substrate, one part is formed by oxidation of a single-crystal silicon thin film layer, and the other part is formed by oxidation of the surface of the silicon carbide substrate bonded to the first donor substrate. Further, the silicon carbide-based composite substrate of this application embodiment also includes a functional layer formed on the side of the oxide layer opposite to the silicon carbide substrate layer.

[0117] Thirdly, embodiments of this application provide a functional device comprising the aforementioned silicon carbide-based composite substrate. Therefore, it possesses the corresponding technical effects and advantages described above.

[0118] To more clearly illustrate the preparation method of the silicon carbide-based composite substrate in the embodiments of this application, several specific embodiments are described below. It should be understood that the specific embodiments described below are merely for explaining the present invention and are not exhaustive examples, nor are they intended to limit the specific scope of the present invention. All equivalent variations based on the technical content of the present invention should be included within the protection scope of the present invention.

[0119] Example 1

[0120] This embodiment provides a method for preparing a silicon carbide-based composite substrate, see [link to documentation]. Figure 2 As shown, the preparation method includes the following steps:

[0121] A silicon carbide substrate 100 and a first donor substrate are provided. The first donor substrate includes a monocrystalline silicon thin film layer 210, a first sacrificial layer 220 located on one side of the thickness direction of the monocrystalline silicon thin film layer 210, and a first separation layer 230 located between the monocrystalline silicon thin film layer 210 and the first sacrificial layer 220. Specifically, the method for providing the first donor substrate in this embodiment is as follows: a first silicon substrate 201 is provided, which is a monocrystalline silicon substrate; a first separation layer 230 is formed in the first silicon substrate 201 by ion implantation, and a monocrystalline silicon thin film layer 210 and a first sacrificial layer 220 are formed on both sides of the first separation layer 230, wherein the monocrystalline silicon thin film layer 210 is formed on the side of the first separation layer 230 closer to the ion implantation direction, and the first sacrificial layer 220 is formed on the side of the first separation layer 230 away from the ion implantation direction. In this embodiment, the implanted ions, ion implantation dose, and ion implantation energy are not limited. For example, the implanted ions are one or more of hydrogen ions and helium ions; the ion implantation dose is 1×10⁻⁶. 16 -1×10 17 ions / cm 2 The ion implantation energy is 1 keV-250 keV. In this embodiment, the thickness of the single-crystal silicon thin film layer 210 is 900 nm.

[0122] The silicon carbide substrate 100 and the first donor substrate are bonded together with the single-crystal silicon thin film layer 210 facing each other. After bonding, the first donor substrate is annealed to vaporize and connect the implanted ions in the first separation layer 230, thereby removing the first sacrificial layer 220 and transferring the single-crystal silicon thin film layer 210 onto the silicon carbide substrate 100. The exposed surface of the single-crystal silicon thin film layer 210 is then polished. For example, the annealing temperature for the first donor substrate is 300°C; the annealing time is 3 hours; and the annealing atmosphere is nitrogen.

[0123] The oxidation process begins on the side of the monocrystalline silicon thin film layer 210 facing away from the silicon carbide substrate 100, so that the entire monocrystalline silicon thin film layer 210 forms a third oxide layer 330, wherein the third oxide layer 330 is formed as an oxide layer. For example, the oxidation temperature for the oxidation process of the monocrystalline silicon thin film layer 210 is 850°C.

[0124] The silicon carbide-based composite substrate prepared by the method of this embodiment includes a silicon carbide substrate layer 100' and an oxide layer located on the silicon carbide substrate layer 100'. The oxide layer is formed only by oxidation treatment of the single-crystal silicon thin film layer 210, and the silicon carbide substrate layer 100' corresponds to the silicon carbide substrate 100.

[0125] Example 2

[0126] This embodiment provides a method for preparing a silicon carbide-based composite substrate, see [link to documentation]. Figure 3 As shown, the preparation method includes the following steps:

[0127] A silicon carbide substrate 100 and a first donor substrate are provided. The first donor substrate includes a monocrystalline silicon thin film layer 210, a first sacrificial layer 220 located on one side of the thickness direction of the monocrystalline silicon thin film layer 210, and a first separation layer 230 located between the monocrystalline silicon thin film layer 210 and the first sacrificial layer 220. Specifically, the method for providing the first donor substrate in this embodiment is as follows: a first silicon substrate 201 is provided, wherein the first silicon substrate 201 is a single-crystal silicon substrate; a first separation layer 230 is preset in the first silicon substrate 201, and the single-crystal silicon thin film layer 210 and the first sacrificial layer 220 are defined by the first separation layer 230; oxidation treatment is performed starting from the side of the single-crystal silicon thin film layer 210 away from the first sacrificial layer 220, so that part of the single-crystal silicon thin film layer 210 is oxidized to form a first oxide layer 310. For example, the oxidation temperature for oxidizing the single-crystal silicon thin film layer 210 is 850°C; the partial oxidation thickness of the single-crystal silicon thin film layer 210 is 20 nm; ion implantation is performed from the side of the partially oxidized single-crystal silicon thin film layer (i.e., the side of the first oxide layer 310) to the first separation layer 230 of the first silicon substrate 201 to form a first separation layer 230 with concentrated implanted ions; the two sides of the first separation layer 230 are the single-crystal silicon thin film layer 210 and the first sacrificial layer 220, respectively. In this embodiment, a single-crystal silicon thin film layer 210 is located on the side of the first separation layer 230 closest to the ion implantation direction, and a first sacrificial layer 220 is located on the side of the first separation layer 230 furthest from the ion implantation direction. In this embodiment, the implanted ions, ion implantation dose, and ion implantation energy are not limited. For example, the implanted ions are one or more of hydrogen ions and helium ions; the ion implantation dose is 1 × 10⁻⁶. 16 -1×10 17 ions / cm 2 The ion implantation energy is 1 keV-250 keV. In this embodiment, the thickness of the single-crystal silicon thin film layer 210 is 500 nm.

[0128] The silicon carbide substrate 100 and the first oxide layer 310 are bonded together with their faces facing each other. After bonding, the first donor substrate is annealed to vaporize and connect the implanted ions in the first separation layer 230, thereby removing the first sacrificial layer 220 and transferring the single-crystal silicon thin film layer 210 onto the silicon carbide substrate 100. The exposed surface of the single-crystal silicon thin film layer 210 is then polished. For example, the annealing temperature for the first donor substrate is 350°C; the annealing time is 2 hours; and the annealing atmosphere is air.

[0129] Oxidation is performed starting from the side of the monocrystalline silicon thin film layer 210 away from the silicon carbide substrate 100, so that the unoxidized portion of the monocrystalline silicon thin film layer 210 forms a second oxide layer 320, wherein the first oxide layer 310 and the second oxide layer 320 together form an oxide layer.

[0130] The silicon carbide-based composite substrate prepared by the method of this embodiment includes a silicon carbide substrate layer 100' and an oxide layer located on the silicon carbide substrate layer 100'. The oxide layer is formed only by oxidation treatment of the single-crystal silicon thin film layer 210, and the silicon carbide substrate layer 100' corresponds to the silicon carbide substrate 100.

[0131] Example 3

[0132] This embodiment provides a method for preparing a silicon carbide-based composite substrate, see [link to documentation]. Figure 4 As shown, the preparation method includes the following steps:

[0133] A silicon carbide substrate 100 and a first donor substrate are provided. The first donor substrate is an SOI substrate, including a monocrystalline silicon thin film layer 210, a first sacrificial layer 220 located on one side of the thickness direction of the monocrystalline silicon thin film layer 210, and an intermediate layer 240 located between the monocrystalline silicon thin film layer 210 and the first sacrificial layer 220. Specifically, the method for providing the first donor substrate in this embodiment is as follows: a second silicon substrate 202 is provided, the second silicon substrate 202 being a monocrystalline silicon substrate; an intermediate layer 240 is formed in the second silicon substrate 202 by oxidation treatment; a monocrystalline silicon thin film layer 210 and a first sacrificial layer 220 are formed on both sides of the intermediate layer 240, respectively. In this embodiment, an oxygen implantation process and an annealing process can be used to oxidize the interior of the second silicon substrate 202 to form the intermediate layer 240, which is a silicon dioxide layer, so that a monocrystalline silicon thin film layer 210 and a first sacrificial layer 220 can be formed on both sides of the intermediate layer 240, respectively. In this embodiment, a monocrystalline silicon thin film layer 210 is formed on the side of the intermediate layer 240 closest to the oxygen injection direction, and a first sacrificial layer 220 is formed on the side of the intermediate layer 240 furthest from the oxygen injection direction. In this embodiment, the thickness of the monocrystalline silicon thin film layer 210 is 800 nm.

[0134] The oxidation process begins on the side of the monocrystalline silicon thin film layer 210 that faces away from the first sacrificial layer 220, so that the entire monocrystalline silicon thin film layer 210 is oxidized to form the third oxide layer 330. For example, the oxidation temperature for oxidizing the monocrystalline silicon thin film layer 210 is 900°C.

[0135] The silicon carbide substrate 100 and the first donor substrate are bonded together with the third oxide layer 330 facing each other. After bonding, the first sacrificial layer 220 is removed by grinding or other methods, and then all intermediate layers 240 are removed by hydrofluoric acid or BOE etching. The third oxide layer 330 is then transferred onto the silicon carbide substrate 100, and the exposed surface of the third oxide layer 330 is polished. The third oxide layer 330 is formed as an oxide layer.

[0136] The silicon carbide-based composite substrate prepared by the method of this embodiment includes a silicon carbide substrate layer 100' and an oxide layer located on the silicon carbide substrate layer 100'. The oxide layer is formed only by oxidation treatment of the single-crystal silicon thin film layer 210, and the silicon carbide substrate layer 100' corresponds to the silicon carbide substrate 100.

[0137] Example 4

[0138] This embodiment provides a method for preparing a silicon carbide-based composite substrate, see [link to documentation]. Figure 5 As shown, the preparation method includes the following steps:

[0139] A silicon carbide substrate 100 and a first donor substrate are provided. The first donor substrate is an SOI substrate, including a monocrystalline silicon thin film layer 210, a first sacrificial layer 220 located on one side of the thickness direction of the monocrystalline silicon thin film layer 210, and an intermediate layer 240 located between the monocrystalline silicon thin film layer 210 and the first sacrificial layer 220. Specifically, the method for providing the first donor substrate in this embodiment is as follows: a second silicon substrate 202 is provided, the second silicon substrate 202 being a monocrystalline silicon substrate; an intermediate layer 240 is formed in the second silicon substrate 202 by oxidation treatment; a monocrystalline silicon thin film layer 210 and a first sacrificial layer 220 are formed on both sides of the intermediate layer 240, respectively. In this embodiment, an oxygen implantation process and an annealing process can be used to oxidize the interior of the second silicon substrate 202 to form the intermediate layer 240, which is a silicon dioxide layer, so that a monocrystalline silicon thin film layer 210 and a first sacrificial layer 220 can be formed on both sides of the intermediate layer 240, respectively. In this embodiment, a monocrystalline silicon thin film layer 210 is formed on the side of the intermediate layer 240 closest to the oxygen injection direction, and a first sacrificial layer 220 is formed on the side of the intermediate layer 240 furthest from the oxygen injection direction. In this embodiment, the thickness of the monocrystalline silicon thin film layer 210 is 1 μm.

[0140] Oxidation is performed starting from the bonding side of the silicon carbide substrate 100, causing the surface of the bonding side of the silicon carbide substrate 100 to be oxidized to form a fourth oxide layer 340, thereby forming a composite structure of silicon carbide substrate layer 100' and fourth oxide layer 340. For example, the oxidation temperature for oxidizing the silicon carbide substrate 100 is 1200°C; the oxidation thickness of the silicon carbide substrate 100 is 8 nm.

[0141] The silicon carbide substrate 100 (corresponding to the composite structure of silicon carbide substrate layer 100' and fourth oxide layer 340) and the first donor substrate are bonded with the fourth oxide layer 340 and the single-crystal silicon thin film layer 210 facing each other. After bonding, the first sacrificial layer 220 is removed by grinding or other means. Then, part of the intermediate layer 240 is removed by hydrofluoric acid or BOE etching. The single-crystal silicon thin film layer 210 and the remaining part of the intermediate layer 240 are transferred together onto the silicon carbide substrate 100. The exposed surface of the remaining part of the intermediate layer 240 is polished.

[0142] The oxidation process begins on the side of the monocrystalline silicon thin film layer 210 facing away from the silicon carbide substrate 100, so that the entire monocrystalline silicon thin film layer 210 forms a third oxide layer 330, wherein the remaining intermediate layer 240, the fourth oxide layer 340, and the third oxide layer 330 are collectively formed as an oxide layer. For example, the oxidation temperature for the oxidation process of the monocrystalline silicon thin film layer 210 is 700°C.

[0143] The silicon carbide-based composite substrate prepared by the method of this embodiment includes a silicon carbide substrate layer 100' and an oxide layer located on the silicon carbide substrate layer 100'. The oxide layer includes three parts: one part is a partial intermediate layer 240 of the first donor substrate, one part is formed by oxidation treatment of the single crystal silicon thin film layer 210, and the other part is formed by surface oxidation of the silicon carbide substrate 100 bonded to the first donor substrate.

[0144] Example 5

[0145] This embodiment provides a method for preparing a silicon carbide-based composite substrate, see [link to documentation]. Figure 6 As shown, the preparation method includes the following steps:

[0146] A silicon carbide substrate 100 and a first donor substrate are provided. The first donor substrate is an SOI substrate, including a monocrystalline silicon thin film layer 210, a first sacrificial layer 220 located on one side of the thickness direction of the monocrystalline silicon thin film layer 210, and an intermediate layer 240 located between the monocrystalline silicon thin film layer 210 and the first sacrificial layer 220. Specifically, the method for providing the first donor substrate in this embodiment is as follows: a second silicon substrate 202 is provided, the second silicon substrate 202 being a monocrystalline silicon substrate; an intermediate layer 240 is formed in the second silicon substrate 202 by oxidation treatment; a monocrystalline silicon thin film layer 210 and a first sacrificial layer 220 are formed on both sides of the intermediate layer 240, respectively. In this embodiment, an oxygen implantation process and an annealing process can be used to oxidize the interior of the second silicon substrate 202 to form the intermediate layer 240, which is a silicon dioxide layer, so that a monocrystalline silicon thin film layer 210 and a first sacrificial layer 220 can be formed on both sides of the intermediate layer 240, respectively. In this embodiment, a monocrystalline silicon thin film layer 210 is formed on the side of the intermediate layer 240 closest to the oxygen injection direction, and a first sacrificial layer 220 is formed on the side of the intermediate layer 240 furthest from the oxygen injection direction. In this embodiment, the thickness of the monocrystalline silicon thin film layer 210 is 1.9 μm.

[0147] Oxidation is performed starting from the side of the single-crystal silicon thin film layer 210 away from the first sacrificial layer 220, causing a portion of the single-crystal silicon thin film layer 210 to be oxidized to form a first oxide layer 310. Exemplarily, the oxidation temperature for oxidizing the single-crystal silicon thin film layer 210 is 1000°C, and the partial oxide thickness of the single-crystal silicon thin film layer 210 is 14 nm. Oxidation is then performed starting from the bonding side of the silicon carbide substrate 100, causing the surface of the bonding side of the silicon carbide substrate 100 to be oxidized to form a fourth oxide layer 340, thereby forming a composite structure of the silicon carbide substrate layer 100' and the fourth oxide layer 340. Exemplarily, the oxidation temperature for oxidizing the silicon carbide substrate 100 is 1300°C, and the oxide thickness of the silicon carbide substrate 100 is 9 nm.

[0148] The silicon carbide substrate 100 (corresponding to the composite structure of silicon carbide substrate layer 100' and fourth oxide layer 340) and the first donor substrate are bonded with the first oxide layer 310 and the fourth oxide layer 340 facing each other. After bonding, the first sacrificial layer 220 is removed by grinding or other means, and the single crystal silicon thin film layer 210 and the intermediate layer 240 are transferred together onto the silicon carbide substrate 100. The exposed surface of the intermediate layer 240 is then polished.

[0149] Oxidation is performed starting from the side of the single-crystal silicon thin film layer 210 away from the silicon carbide substrate 100, so that the unoxidized portion of the single-crystal silicon thin film layer 210 forms a second oxide layer 320, wherein the intermediate layer 240, the first oxide layer 310, the second oxide layer 320 and the fourth oxide layer 340 are collectively formed as an oxide layer.

[0150] The silicon carbide-based composite substrate prepared by the method of this embodiment includes a silicon carbide substrate layer 100' and an oxide layer located on the silicon carbide substrate layer 100'. The oxide layer comprises three parts: one part is an intermediate layer 240 of the first donor substrate, one part is formed by oxidation of the single crystal silicon thin film layer 210, and the other part is formed by surface oxidation of the silicon carbide substrate 100 bonded to the first donor substrate.

[0151] Example 6

[0152] This embodiment provides a method for preparing a silicon carbide-based composite substrate, see [link to documentation]. Figure 7 As shown, the preparation method includes the following steps:

[0153] A silicon carbide substrate 100 and a first donor substrate are provided. The first donor substrate is an SOI substrate, including a monocrystalline silicon thin film layer 210, a first sacrificial layer 220 located on one side of the thickness direction of the monocrystalline silicon thin film layer 210, and an intermediate layer 240 located between the monocrystalline silicon thin film layer 210 and the first sacrificial layer 220. Specifically, the method for providing the first donor substrate in this embodiment is as follows: a second silicon substrate 202 is provided, the second silicon substrate 202 being a monocrystalline silicon substrate; an intermediate layer 240 is formed in the second silicon substrate 202 by oxidation treatment; a monocrystalline silicon thin film layer 210 and a first sacrificial layer 220 are formed on both sides of the intermediate layer 240, respectively. In this embodiment, an oxygen implantation process and an annealing process can be used to oxidize the interior of the second silicon substrate 202 to form the intermediate layer 240, which is a silicon dioxide layer, so that a monocrystalline silicon thin film layer 210 and a first sacrificial layer 220 can be formed on both sides of the intermediate layer 240, respectively. In this embodiment, a monocrystalline silicon thin film layer 210 is formed on the side of the intermediate layer 240 closest to the oxygen injection direction, and a first sacrificial layer 220 is formed on the side of the intermediate layer 240 furthest from the oxygen injection direction. In this embodiment, the thickness of the monocrystalline silicon thin film layer 210 is 2 μm.

[0154] Oxidation is performed starting from the side of the single-crystal silicon thin film layer 210 away from the first sacrificial layer 220, so that the entire single-crystal silicon thin film layer 210 is oxidized to form a third oxide layer 330. Exemplarily, the oxidation temperature for oxidizing the single-crystal silicon thin film layer 210 is 780°C. Oxidation is then performed starting from the bonding side of the silicon carbide substrate 100, so that the surface of the bonding side of the silicon carbide substrate 100 is oxidized to form a fourth oxide layer 340, thereby forming a composite structure of the silicon carbide substrate layer 100' and the fourth oxide layer 340. Exemplarily, the oxidation temperature for oxidizing the silicon carbide substrate 100 is 1250°C; the oxide thickness of the silicon carbide substrate 100 is 5 nm.

[0155] A silicon carbide substrate 100 (corresponding to a composite structure of silicon carbide substrate layer 100' and fourth oxide layer 340) and a first donor substrate are bonded with the third oxide layer 330 and fourth oxide layer 340 facing each other. After bonding, the first sacrificial layer 220 is removed by grinding or other methods, and then all intermediate layers 240 are removed by hydrofluoric acid or BOE etching. The third oxide layer 330 is then transferred onto the silicon carbide substrate 100, and the exposed surface of the third oxide layer 330 is polished. The third oxide layer 330 and the fourth oxide layer 340 together form an oxide layer.

[0156] The silicon carbide-based composite substrate prepared by the method of this embodiment includes a silicon carbide substrate layer 100' and an oxide layer located on the silicon carbide substrate layer 100'. The oxide layer comprises two parts: one part is formed by oxidation of the single-crystal silicon thin film layer 210, and the other part is formed by surface oxidation of the silicon carbide substrate 100 bonded to the first donor substrate.

[0157] Example 7

[0158] This embodiment provides a method for preparing a silicon carbide-based composite substrate, see [link to documentation]. Figure 8 As shown, the preparation method includes the following steps:

[0159] A silicon carbide substrate 100 and a first donor substrate are provided. The first donor substrate includes a monocrystalline silicon thin film layer 210, a first sacrificial layer 220 located on one side of the thickness direction of the monocrystalline silicon thin film layer 210, and a first separation layer 230 located between the monocrystalline silicon thin film layer 210 and the first sacrificial layer 220. Specifically, the method for providing the first donor substrate in this embodiment is as follows: a first silicon substrate 201 is provided, which is a monocrystalline silicon substrate; a first separation layer 230 is formed in the first silicon substrate 201 by ion implantation, and a monocrystalline silicon thin film layer 210 and a first sacrificial layer 220 are formed on both sides of the first separation layer 230, respectively. The monocrystalline silicon thin film layer 210 is formed on the side of the first separation layer 230 closer to the ion implantation direction, and the first sacrificial layer 220 is formed on the side of the first separation layer 230 away from the ion implantation direction. In this embodiment, the implanted ions, ion implantation dose, and ion implantation energy are not limited. For example, the implanted ions are one or more of hydrogen ions and helium ions; the ion implantation dose is 1×10⁻⁶. 16 -1×10 17 ions / cm 2 The ion implantation energy is 1 keV-250 keV. In this embodiment, the thickness of the single-crystal silicon thin film layer 210 is 70 nm.

[0160] The silicon carbide substrate 100 and the first donor substrate are bonded together with the single-crystal silicon thin film layer 210 facing each other. After bonding, the first donor substrate is annealed to vaporize and connect the implanted ions in the first separation layer 230, thereby removing the first sacrificial layer 220 and transferring the single-crystal silicon thin film layer 210 onto the silicon carbide substrate 100. The exposed surface of the single-crystal silicon thin film layer 210 is then polished. For example, the annealing temperature for the first donor substrate is 330°C; the annealing time is 2.5 hours; and the annealing atmosphere is nitrogen.

[0161] Oxidation is performed starting from the side of the single-crystal silicon thin film layer 210 facing away from the silicon carbide substrate 100, so that the entire single-crystal silicon thin film layer 210 forms a third oxide layer 330, and the surface of the silicon carbide substrate 100 bonded to the first donor substrate is oxidized to form a fourth oxide layer 340, wherein the third oxide layer 330 and the fourth oxide layer 340 are together formed as an oxide layer. For example, the oxidation temperature for oxidizing the single-crystal silicon thin film layer 210 is 730°C; the oxidation temperature for oxidizing the silicon carbide substrate 100 is 1150°C; and the oxide thickness of the silicon carbide substrate 100 is 6.5 nm.

[0162] The silicon carbide-based composite substrate prepared by the method of this embodiment includes a silicon carbide substrate layer 100' and an oxide layer located on the silicon carbide substrate layer 100'. The oxide layer comprises two parts: one part is formed by oxidation of the single-crystal silicon thin film layer 210, and the other part is formed by surface oxidation of the silicon carbide substrate 100 bonded to the first donor substrate.

[0163] Example 8

[0164] This embodiment provides a method for preparing a silicon carbide-based composite substrate, see [link to documentation]. Figure 9 As shown, the preparation method includes the following steps:

[0165] A silicon carbide substrate 100 and a first donor substrate are provided. The first donor substrate includes a monocrystalline silicon thin film layer 210, a first sacrificial layer 220 located on one side of the thickness direction of the monocrystalline silicon thin film layer 210, and a first separation layer 230 located between the monocrystalline silicon thin film layer 210 and the first sacrificial layer 220. Specifically, the method for providing the first donor substrate in this embodiment is as follows: a first silicon substrate 201 is provided, wherein the first silicon substrate 201 is a single-crystal silicon substrate; a first separation layer 230 is preset in the first silicon substrate 201, and the single-crystal silicon thin film layer 210 and the first sacrificial layer 220 are defined by the first separation layer 230; oxidation treatment is performed starting from the side of the single-crystal silicon thin film layer 210 away from the first sacrificial layer 220, so that part of the single-crystal silicon thin film layer 210 is oxidized to form a first oxide layer 310. For example, the oxidation temperature of the single-crystal silicon thin film layer 210 is 830°C; the partial oxidation thickness of the single-crystal silicon thin film layer 210 is 15nm; ion implantation is performed from the side of the partially oxidized single-crystal silicon thin film layer (i.e., the side of the first oxide layer 310) to the first separation layer 230 of the first silicon substrate 201 to form a first separation layer 230 with concentrated implanted ions, wherein the two sides of the first separation layer 230 are the single-crystal silicon thin film layer 210 and the first sacrificial layer 220, respectively. In this embodiment, a single-crystal silicon thin film layer 210 is located on the side of the first separation layer 230 closest to the ion implantation direction, and a first sacrificial layer 220 is located on the side of the first separation layer 230 furthest from the ion implantation direction. In this embodiment, the implanted ions, ion implantation dose, and ion implantation energy are not limited. For example, the implanted ions are one or more of hydrogen ions and helium ions; the ion implantation dose is 1 × 10⁻⁶. 16 -1×10 17 ions / cm 2 The ion implantation energy is 1 keV-250 keV. In this embodiment, the thickness of the monocrystalline silicon thin film layer 210 is 1.6 μm.

[0166] The silicon carbide substrate 100 and the first oxide layer 310 are bonded together with the silicon carbide substrate 100 and the first donor substrate facing each other. After bonding, the first donor substrate is annealed to vaporize and connect the implanted ions in the first separation layer 230, thereby removing the first sacrificial layer 220 and transferring the single-crystal silicon thin film layer 210 onto the silicon carbide substrate 100. The exposed surface of the single-crystal silicon thin film layer 210 is then polished. For example, the annealing temperature for the first donor substrate is 220°C; the annealing time is 4.5 hours; and the annealing atmosphere is nitrogen.

[0167] Oxidation is performed starting from the side of the single-crystal silicon thin film layer 210 facing away from the silicon carbide substrate 100, such that the unoxidized portion of the single-crystal silicon thin film layer 210 forms a second oxide layer 320, and the surface of the silicon carbide substrate 100 bonded to the first donor substrate is oxidized to form a fourth oxide layer 340. The first oxide layer 310, the second oxide layer 320, and the fourth oxide layer 340 are collectively formed as an oxide layer. For example, the oxidation temperature for oxidizing the silicon carbide substrate 100 is 1150°C. The oxide thickness of the silicon carbide substrate 100 is 9.5 nm.

[0168] The silicon carbide-based composite substrate prepared by the method of this embodiment includes a silicon carbide substrate layer 100' and an oxide layer located on the silicon carbide substrate layer 100'. The oxide layer comprises two parts: one part is formed by oxidation of the single-crystal silicon thin film layer 210, and the other part is formed by surface oxidation of the silicon carbide substrate 100 bonded to the first donor substrate.

[0169] Example 9

[0170] This embodiment provides a method for preparing a silicon carbide-based composite substrate, see [link to documentation]. Figure 10 As shown, the preparation method includes the following steps:

[0171] A silicon carbide substrate 100 and a first donor substrate are provided. The first donor substrate includes a monocrystalline silicon thin film layer 210, a first sacrificial layer 220 located on one side of the thickness direction of the monocrystalline silicon thin film layer 210, and a first separation layer 230 located between the monocrystalline silicon thin film layer 210 and the first sacrificial layer 220. Specifically, the method for providing the first donor substrate in this embodiment is as follows: a first silicon substrate 201 is provided, wherein the first silicon substrate 201 is a single-crystal silicon substrate; a first separation layer 230 is pre-set in the first silicon substrate 201, and the single-crystal silicon thin film layer 210 and the first sacrificial layer 220 are defined by the first separation layer 230; oxidation treatment is performed starting from the side of the single-crystal silicon thin film layer 210 away from the first sacrificial layer 220, so that all of the single-crystal silicon thin film layer 210 is oxidized to form a third oxide layer 330. For example, the oxidation temperature for oxidizing the single-crystal silicon thin film layer 210 is 930°C; ion implantation is performed from the third oxide layer 330 side towards the first separation layer 230 of the first silicon substrate 201 to form a first separation layer 230 with concentrated implanted ions. The two sides of the first separation layer 230 are the third oxide layer 330 and the first sacrificial layer 220, respectively. Wherein, the side of the first separation layer 230 closer to the ion implantation direction is the third oxide layer 330, and the side of the first separation layer 230 away from the ion implantation direction is the first sacrificial layer 220. In this embodiment, the implanted ion, ion implantation dose, and ion implantation energy are not limited. For example, the implanted ion is one or more of hydrogen ions and helium ions; the ion implantation dose is 1×10⁻⁶. 16 -1×1017 ions / cm 2 The ion implantation energy is 1 keV-250 keV. In this embodiment, the thickness of the single-crystal silicon thin film layer 210 is 20 nm.

[0172] The silicon carbide substrate 100 and the first donor substrate are bonded together with the third oxide layer 330 facing each other. After bonding, the first donor substrate is annealed to vaporize and connect the implanted ions in the first separation layer 230, thereby removing the first sacrificial layer 220 and transferring the third oxide layer 330 onto the silicon carbide substrate 100. The exposed surface of the third oxide layer 330 is then polished. For example, the annealing temperature for the first donor substrate is 270°C; the annealing time is 3.5 hours; and the annealing atmosphere is nitrogen.

[0173] Oxidation is performed starting from the side of the third oxide layer 330 facing away from the silicon carbide substrate 100, causing the surface of the silicon carbide substrate 100 bonded to the first donor substrate to be oxidized to form a fourth oxide layer 340. The third oxide layer 330 and the fourth oxide layer 340 together form an oxide layer. For example, the oxidation temperature for oxidizing the silicon carbide substrate 100 is 1270°C; the oxidation thickness of the silicon carbide substrate 100 is 8.4 nm.

[0174] The silicon carbide-based composite substrate prepared by the method of this embodiment includes a silicon carbide substrate layer 100' and an oxide layer located on the silicon carbide substrate layer 100'. The oxide layer comprises two parts: one part is formed by oxidation of the single-crystal silicon thin film layer 210, and the other part is formed by surface oxidation of the silicon carbide substrate 100 bonded to the first donor substrate.

[0175] Example 10

[0176] This embodiment provides a method for preparing a silicon carbide-based composite substrate, based on any of the preparation methods in Embodiments 1 to 9, specifically, after forming an oxide layer on the bonding side of the silicon carbide substrate layer 100', see [link to previous embodiment]. Figure 11 As shown, it further includes the following steps:

[0177] A second donor substrate 250 is provided, which includes at least a functional layer 251 and a second sacrificial layer 252 located on one side of the functional layer 251 in the thickness direction. In this embodiment, the second donor substrate 250 is an ion-implanted wafer that has undergone ion implantation. Through ion implantation, a second separation layer 253 can be formed inside the second donor substrate 250, and the functional layer 251 and the second sacrificial layer 252 are formed on both sides of the second separation layer 253, respectively. The functional layer 251 is formed on the side of the second separation layer 253 closer to the ion implantation direction, and the second sacrificial layer 252 is formed on the side of the second separation layer 253 away from the ion implantation direction. In this embodiment, the implanted ions, ion implantation dose, and ion implantation energy are not limited. For example, the implanted ions are one or more of hydrogen ions, helium ions, nitrogen ions, oxygen ions, or argon ions; the ion implantation dose is 1×10⁻⁶. 16 -3×10 17 ions / cm 2 The ion implantation energy is 30 keV-5 MeV. In this embodiment, the material of the second donor substrate 250 is not limited and can be at least one of lithium niobate, lithium tantalate, silicon carbide, silicon, gallium nitride, and gallium arsenide. Correspondingly, the material of the functional layer 251 is at least one of lithium niobate, lithium tantalate, silicon carbide, silicon, gallium nitride, and gallium arsenide.

[0178] The oxide layer and the second donor substrate 250 are bonded together with the functional layer 251 and the oxide layer facing each other.

[0179] The second sacrificial layer 252 is removed, thereby transferring the functional layer 251 onto the silicon carbide substrate 100' and the oxide layer. In this embodiment, the second donor substrate 250 is annealed, causing the implanted ions in the second separation layer 253 to vaporize and connect, thereby allowing the second sacrificial layer 252 to be peeled off and removed, thus transferring the functional layer 251 onto the silicon carbide substrate 100' and the oxide layer. Exemplarily, the annealing temperature for the second donor substrate 250 is 100°C-600°C; the annealing time is 1h-24h; and the annealing atmosphere is air or nitrogen. In this embodiment, after removing the second sacrificial layer 252 from the second donor substrate 250, the exposed surface of the functional layer 251 is polished.

[0180] The silicon carbide-based composite substrate prepared by the method of this embodiment includes a silicon carbide substrate layer 100', an oxide layer on the silicon carbide substrate layer 100', and a functional layer 251 on the oxide layer.

[0181] Example 11

[0182] This embodiment provides a method for preparing a silicon carbide-based composite substrate, based on any of the preparation methods in Embodiments 1 to 9, specifically, after forming an oxide layer on the bonding side of the silicon carbide substrate layer 100', see [link to previous embodiment]. Figure 12 As shown, it further includes the following steps:

[0183] A second donor substrate 250 is provided, which includes at least a functional layer 251 and a second sacrificial layer 252 located on one side of the thickness direction of the functional layer 251. In this embodiment, the material of the second donor substrate 250 is not limited and can be at least one of lithium niobate, lithium tantalate, silicon carbide, silicon, gallium nitride, and gallium arsenide. Correspondingly, the material of the functional layer 251 is at least one of lithium niobate, lithium tantalate, silicon carbide, silicon, gallium nitride, and gallium arsenide.

[0184] The oxide layer and the second donor substrate 250 are bonded together with the functional layer 251 and the oxide layer facing each other.

[0185] The second sacrificial layer 252 is removed by grinding, thereby transferring the functional layer 251 onto the silicon carbide substrate 100' and the oxide layer. The exposed surface of the functional layer 251 is then polished.

[0186] The silicon carbide-based composite substrate prepared by the method of this embodiment includes a silicon carbide substrate layer 100', an oxide layer on the silicon carbide substrate layer 100', and a functional layer 251 on the oxide layer.

[0187] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for preparing a silicon carbide-based composite substrate, characterized in that, include: A silicon carbide substrate (100) and a first donor substrate are provided; The first donor substrate includes at least a single-crystal silicon thin film layer (210) and a first sacrificial layer (220) located on one side of the thickness direction of the single-crystal silicon thin film layer (210). The silicon carbide substrate (100) and the first donor substrate are bonded together with the silicon carbide substrate (100) and the single crystal silicon thin film layer (210) facing each other. Remove the first sacrificial layer (220) and form an oxide layer on the bonding side of the silicon carbide substrate (100).

2. The preparation method according to claim 1, characterized in that, Before bonding the silicon carbide substrate (100) and the first donor substrate, all of the single-crystal silicon thin film layer (210) is oxidized. Alternatively, before bonding the silicon carbide substrate (100) and the first donor substrate, a portion of the single-crystal silicon thin film layer (210) is oxidized from the bonding side, and the remaining portion of the single-crystal silicon thin film layer (210) is oxidized after the first sacrificial layer (220) is removed. Alternatively, after removing the first sacrificial layer (220), all of the monocrystalline silicon thin film layers (210) may be oxidized.

3. The preparation method according to claim 1, characterized in that, The formation of an oxide layer on the bonding side of the silicon carbide substrate (100) includes: Oxidation treatment of all of the single-crystal silicon thin film layers (210); and, The silicon carbide substrate (100) is oxidized to bond the surface of the first donor substrate.

4. The preparation method according to any one of claims 1-3, characterized in that, Before bonding the silicon carbide substrate (100) and the first donor substrate, the surface of the silicon carbide substrate (100) bonded to the first donor substrate is oxidized. Alternatively, after removing the first sacrificial layer (220), the silicon carbide substrate (100) is oxidized to bond the surface of the first donor substrate.

5. The preparation method according to any one of claims 1-3, characterized in that, The provision of the first donor substrate includes: A first silicon substrate (201) is provided; A first separation layer (230) is formed in the first silicon substrate (201) by ion implantation; a single crystal silicon thin film layer (210) and a first sacrificial layer (220) are formed on both sides of the first separation layer (230). The removal of the first sacrificial layer (220) includes: The first donor substrate is annealed.

6. The preparation method according to claim 5, characterized in that, When providing the first donor substrate involves oxidizing all or part of the single-crystal silicon thin film layer (210) before bonding the silicon carbide substrate (100) and the first donor substrate, the provision of the first donor substrate includes: A first silicon substrate (201) is provided, and a first separation layer (230) is preset in the first silicon substrate (201) to define the single crystal silicon thin film layer (210) and the first sacrificial layer (220). Oxidation treatment of all or part of the monocrystalline silicon thin film layer (210). Ion implantation is performed on the first separation layer (230) of the first silicon substrate (201) after the self-oxidation treatment of the single crystal silicon thin film layer (210).

7. The preparation method according to any one of claims 1-3, characterized in that, The provision of the first donor substrate includes: A second silicon substrate (202) is provided; An intermediate layer (240) is formed in the second silicon substrate (202) by oxidation treatment; a single crystal silicon thin film layer (210) and the first sacrificial layer (220) are formed on both sides of the intermediate layer (240). The removal of the first sacrificial layer (220) includes: From the side of the second silicon substrate (202) away from the silicon carbide substrate (100), only the first sacrificial layer (220) is removed, or the first sacrificial layer (220) and at least part of the intermediate layer (240) are removed.

8. The preparation method according to any one of claims 1-3, characterized in that, After forming an oxide layer on the bonding side of the silicon carbide substrate (100), the method further includes: A second donor substrate (250) is provided; the second donor substrate (250) includes at least a functional layer (251) and a second sacrificial layer (252) located on one side of the thickness direction of the functional layer (251); The oxide layer and the second donor substrate (250) are bonded together with the functional layer (251) and the oxide layer facing each other. Remove the second sacrificial layer (252).

9. A silicon carbide-based composite substrate, characterized in that, Prepared by the preparation method according to any one of claims 1-8; The silicon carbide-based composite substrate includes: Silicon carbide substrate (100'); An oxide layer is located on one side of the silicon carbide substrate layer (100'); the oxide layer is formed by oxidation of at least a single-crystal silicon thin film layer (210).

10. A functional device, characterized in that, Including the silicon carbide-based composite substrate as described in claim 9.

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