A silicon-on-insulator substrate and a method for manufacturing the same

Abstract

The application provides a silicon-on-insulator substrate and a preparation method thereof, and the silicon-on-insulator substrate comprises the following steps: providing a first substrate and a second substrate; forming an insulating layer and at least one heat-conducting structure in the insulating layer on the surface of at least one of the first substrate and the second substrate, wherein each heat-conducting structure comprises at least one first insulating heat-conducting layer and at least one second insulating heat-conducting layer, the thermal conductivity of the first insulating heat-conducting layer is greater than that of the insulating layer, and the thermal conductivity of the second insulating heat-conducting layer is greater than that of the insulating layer; bonding the first substrate and the second substrate, and the insulating layer and the heat-conducting structure are located between the bonded first substrate and second substrate; and stripping the second substrate to remove part of the second substrate, and the remaining second substrate serves as a top semiconductor layer, and the first substrate serves as a base layer of the silicon-on-insulator substrate. The application embeds the heat-conducting structure in the insulating layer, conducts the heat of the top semiconductor layer to the base layer, and improves the heat dissipation performance of the silicon-on-insulator substrate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor technology, in particular to a silicon-on-insulator substrate and a preparation method thereof. BACKGROUND

[0002] As an advanced semiconductor substrate material, a silicon-on-insulator (SOI) substrate has advantages of small parasitic capacitance, weak short channel effect, high speed, low power consumption, etc., and has been widely applied in high-frequency devices, power devices, radio frequency circuits, integrated circuits, etc. The structure of a conventional SOI substrate usually comprises a top semiconductor layer, an insulating layer and a substrate layer, and the core feature is that the top semiconductor layer is electrically isolated from the substrate layer through the insulating layer.

[0003] At present, the preparation method of the SOI substrate is smart cut technology, and the basic process is as follows: first, two wafers are prepared, one of which is subjected to thermal oxidation treatment to form a buried oxide (BOX) layer, and the wafer is subjected to hydrogen ion implantation to form a weakened layer, and the other wafer is not treated; second, the two wafers are bonded, and the weakened layer enriched with hydrogen ions is induced to fracture by annealing, so as to realize the transfer of the top thin film to form the top semiconductor layer; finally, the bonding interface is strengthened by high-temperature annealing, and the top semiconductor layer is planarized by chemical mechanical polishing, and finally the SOI substrate is formed.

[0004] In the related art, the thermal conductivity of the insulating layer of the SOI substrate is low, and a large amount of heat is generated in the active region formed in the top semiconductor layer during the working process due to current transmission. Due to the heat insulation effect of the insulating layer, the heat is difficult to transfer to the substrate layer, resulting in an increase in the temperature of the top semiconductor layer, which seriously affects the performance of the device. In addition, there is a significant difference in the thermal expansion coefficient of the material of the SOI substrate. During the high-temperature process, due to the inconsistent thermal expansion behavior of each layer of material, residual thermal stress is generated at the interface after cooling. The uneven stress distribution causes the wafer to warp, that is, the vertical distance between the center and the edge of the wafer (i.e. the Bow value) is large, which affects the morphology of each layer of the SOI substrate, thereby making the process monitoring of each layer inaccurate, and increasing the process time and cost to improve the influence caused by the warping. SUMMARY

[0005] A series of simplified concepts are introduced in the summary section, which will be further described in detail in the specific embodiment section. The summary section of the present application does not mean to attempt to limit the key features and necessary technical features of the claimed technical solution, and even less to determine the protection scope of the claimed technical solution.

[0006] In view of the existing problems, the application provides a preparation method of a silicon-on-insulator substrate, which comprises the following steps: providing a first substrate and a second substrate; at least one of the first substrate and the second substrate is provided with an insulating layer and at least one heat-conducting structure in the insulating layer, each of the heat-conducting structures comprises at least one first insulating heat-conducting layer and at least one second insulating heat-conducting layer, the thermal conductivity of the first insulating heat-conducting layer is greater than that of the insulating layer, and the thermal conductivity of the second insulating heat-conducting layer is greater than that of the insulating layer; bonding the first substrate and the second substrate, the insulating layer and the heat-conducting structure are located between the first substrate and the second substrate after bonding; and stripping the second substrate to remove part of the second substrate, and the remaining second substrate serves as a top semiconductor layer, and the first substrate serves as a base layer of the silicon-on-insulator substrate.

[0007] Exemplarily, the method for forming the at least one heat-conducting structure in the insulating layer comprises the following steps: etching the insulating layer to form at least one groove penetrating through the insulating layer; forming the first insulating heat-conducting layer on the bottom and the sidewall of the groove; and forming the second insulating heat-conducting layer on the first insulating heat-conducting layer and filling the groove to form the heat-conducting structure.

[0008] Exemplarily, when the surface of the first substrate and the surface of the second substrate are both provided with the insulating layer, the method for forming the at least one heat-conducting structure in the insulating layer comprises the following steps: etching the insulating layer of the first substrate to form at least one first groove penetrating through the insulating layer of the first substrate, etching the insulating layer of the second substrate to form at least one second groove penetrating through the insulating layer of the second substrate, and the positions of the first groove and the second groove correspond to each other; forming the first insulating heat-conducting layer on the bottom and the sidewall of the first groove and the second groove; forming the second insulating heat-conducting layer on the first insulating heat-conducting layer of the first groove and the second groove, the second insulating heat-conducting layer in the first groove fills the first groove, and the second insulating heat-conducting layer in the second groove fills the second groove; wherein the first insulating heat-conducting layer and the second insulating heat-conducting layer of the first groove constitute a first heat-conducting structure, and the first insulating heat-conducting layer and the second insulating heat-conducting layer of the second groove constitute a second heat-conducting structure; and the bonding of the first substrate and the second substrate comprises the following step: bonding the side of the first substrate provided with the insulating layer and the side of the second substrate provided with the insulating layer, wherein the first heat-conducting structure and the second heat-conducting structure correspond to each other, and the first heat-conducting structure and the second heat-conducting structure are connected to constitute a composite heat-conducting structure after the bonding.

[0009] Exemplarily, forming the surface of at least one of the first substrate and the second substrate into an insulation layer and at least one heat-conducting structure in the insulation layer comprises: forming at least one layer of a first heat-conducting material and at least one layer of a second heat-conducting material on the surface of at least one of the first substrate and the second substrate; etching the first heat-conducting material and the second heat-conducting material to form a groove through the first heat-conducting material and the second heat-conducting material; and filling the groove with an insulation material to form the insulation layer; wherein the remaining first heat-conducting material forms the first insulation heat-conducting layer, and the remaining second heat-conducting material forms the second insulation heat-conducting layer, and the first insulation heat-conducting layer and the second insulation heat-conducting layer form the heat-conducting structure.

[0010] Exemplarily, the first insulation heat-conducting layer and the second insulation heat-conducting layer are different heat-conducting materials, wherein the material of the first insulation heat-conducting layer is boron nitride or aluminum nitride, and the material of the second insulation heat-conducting layer is boron nitride or aluminum nitride; and / or the insulation layer comprises at least one layer of the first insulation heat-conducting layer and at least one layer of the second insulation heat-conducting layer.

[0011] Exemplarily, before bonding the first substrate and the second substrate, the method further comprises: ion implanting the second substrate to form a weakened layer for guiding the fracture to form the top semiconductor layer in the peeling process; and / or after the peeling process of the second substrate, the method further comprises: performing a chemical mechanical planarization process on the top semiconductor layer.

[0012] Another aspect of the present application provides a silicon-on-insulator substrate, comprising: a base layer; an insulation layer on the base layer; at least one heat-conducting structure in the insulation layer, each of the heat-conducting structures comprising at least one layer of a first insulation heat-conducting layer and at least one layer of a second insulation heat-conducting layer, wherein the thermal conductivity of the first insulation heat-conducting layer is greater than that of the insulation layer, and the thermal conductivity of the second insulation heat-conducting layer is greater than that of the insulation layer; and a top semiconductor layer on the heat-conducting structure.

[0013] Exemplarily, the first insulation heat-conducting layer and the second insulation heat-conducting layer are different heat-conducting materials, wherein the material of the first insulation heat-conducting layer is boron nitride or aluminum nitride, and the material of the second insulation heat-conducting layer is boron nitride or aluminum nitride; and / or the insulation layer comprises at least one layer of the first insulation heat-conducting layer and at least one layer of the second insulation heat-conducting layer.

[0014] Exemplarily, the base layer is a silicon substrate or a silicon carbide substrate.

[0015] Exemplarily, the heat-conducting structure penetrates the insulating layer, one end of the heat-conducting structure is connected to the base layer, and the other end of the heat-conducting structure is connected to the top semiconductor layer.

[0016] The silicon-on-insulator substrate and the preparation method thereof provided by the application embed at least one heat-conducting structure in the insulating layer in the silicon-on-insulator substrate, the heat-conducting structure is composed of a first insulating heat-conducting layer and a second insulating heat-conducting layer, and the first insulating heat-conducting layer and the second insulating heat-conducting layer are both materials with high thermal conductivity and high electrical insulation, therefore, the heat-conducting structure can rapidly conduct the heat of the top semiconductor layer to the base layer, improve the heat dissipation performance of the silicon-on-insulator substrate, and further improve the reliability of the device, in addition, the high mechanical strength of the heat-conducting structure also improves the hardness and rigidity of the silicon-on-insulator substrate, improves the Bow value, and avoids consuming more process time and material cost in subsequent processes. BRIEF DESCRIPTION OF DRAWINGS

[0017] The following drawings for the application are hereby included as part of the present application for purposes of illustrating the application and, in which:

[0018] In the drawings:

[0019] Figure 1 A structure schematic diagram of a silicon-on-insulator substrate of a related art is shown;

[0020] Figure 2 A flow chart of a preparation method of a silicon-on-insulator substrate of an embodiment of the application is shown;

[0021] Figures 3 to 16 A schematic diagram of a silicon-on-insulator substrate obtained by sequentially implementing the preparation method of the silicon-on-insulator substrate of an embodiment of the application is shown. DETAILED DESCRIPTION

[0022] The application will be described in more detail with reference to the drawings, in which embodiments of the application are shown. The application may, however, be embodied in different forms without departing from the spirit or essential characteristics thereof. Rather, the embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art. In the drawings, the sizes and relative sizes of layers and regions are exaggerated for clarity. Identical reference numerals have been used, where applicable, to designate corresponding elements throughout the figures.

[0023] It will be understood that when an element or layer is referred to as being "on" or "connected to" another element or layer, it can be directly on or connected to the other element or layer or intervening elements or layers can be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present application.

[0024] Spatially relative terms, such as "beneath", "below", "lower", "under", "above", "upper" and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0025] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0026] For a thorough understanding of the present application, reference will be made to the following detailed description taken in conjunction with the accompanying drawings, in which:

[0027] In the related art, as shown in Figure 1 The thermal conductivity of the insulating layer of a silicon-on-insulator (SOI) substrate is low. When the active region formed by the top semiconductor layer 21 generates a large amount of heat due to current transmission during operation, the heat is difficult to transfer to the base layer 22 due to the heat insulation effect of the insulating layer 11, which causes the temperature of the top semiconductor layer 21 to rise, and seriously affects the performance of the device in a long-term working state. In addition, the thermal expansion coefficients of the materials of the SOI substrate are significantly different. During high-temperature processes, due to the inconsistent thermal expansion behaviors of the materials of the layers, residual thermal stress is generated at the interface after cooling. The uneven stress distribution causes the wafer to warp, that is, the vertical distance between the center and the edge of the wafer (i.e., the Bow value) is large, which affects the topography of the layers of the SOI substrate, thereby making the process monitoring of the layers inaccurate, and the process time and cost need to be increased to improve the impact of the warping.

[0028] Therefore, in view of the foregoing technical problems, the present application proposes a preparation method of a silicon-on-insulator substrate, as shown in Figure 2 which mainly includes the following steps:

[0029] Step S1, providing a first substrate and a second substrate;

[0030] Step S2, forming an insulating layer and at least one heat-conducting structure located in the insulating layer on the surface of at least one of the first substrate and the second substrate, each heat-conducting structure including at least one first insulating heat-conducting layer and at least one second insulating heat-conducting layer, wherein the thermal conductivity of the first insulating heat-conducting layer is greater than the thermal conductivity of the insulating layer, and the thermal conductivity of the second insulating heat-conducting layer is greater than the thermal conductivity of the insulating layer;

[0031] Step S3, bonding the first substrate and the second substrate, and the insulating layer and the heat-conducting structure are located between the bonded first substrate and the second substrate;

[0032] Step S4, stripping the second substrate to remove part of the second substrate, and the remaining second substrate serves as a top semiconductor layer, and the first substrate serves as a base layer of a silicon-on-insulator substrate.

[0033] The silicon-on-insulator substrate and the preparation method thereof, by embedding at least one heat conduction structure in the insulating layer in the silicon-on-insulator substrate, the heat conduction structure is composed of a first insulating heat conduction layer and a second insulating heat conduction layer, and the first insulating heat conduction layer and the second insulating heat conduction layer are both materials with high thermal conductivity and high electrical insulation, therefore, the heat conduction structure can quickly conduct the heat of the top semiconductor layer to the base layer, improve the heat dissipation performance of the silicon-on-insulator substrate, and further improve the reliability of the device, in addition, the high mechanical strength of the heat conduction structure also improves the hardness and stiffness of the silicon-on-insulator substrate, improves the Bow value, and avoids consuming more process time and material cost in the subsequent process.

[0034] Embodiment one

[0035] Next, with reference to Figure 2 and Figures 3 to 16 The preparation method of the silicon-on-insulator substrate of the present application is described in detail, wherein, Figure 2 The flow chart of the preparation method of the silicon-on-insulator substrate of one specific embodiment of the present application is shown, Figures 3 to 16 The schematic diagram of the silicon-on-insulator substrate obtained by sequentially implementing the preparation method of the silicon-on-insulator substrate of one specific embodiment of the present application is shown.

[0036] Exemplarily, the preparation method of the silicon-on-insulator substrate of the present application includes the following steps:

[0037] Firstly, step S1 is performed to provide a first substrate 10 and a second substrate 20.

[0038] In one example, as Figure 3 shown, the first substrate 10 and the second substrate 20 are provided. Exemplarily, the first substrate 10 and the second substrate 20 can be the same or different materials, wherein the first substrate 10 can be a silicon substrate or a silicon carbide substrate, etc., and the second substrate 20 can be a silicon substrate, etc., which is not specifically limited. When the first substrate 10 is a silicon carbide substrate, it can have higher heat dissipation effect, and the second substrate 20 is used for subsequent formation of the top semiconductor layer.

[0039] Secondly, step S2 is performed to form an insulating layer and at least one heat conduction structure in the insulating layer on the surface of at least one of the first substrate and the second substrate, each heat conduction structure includes at least one first insulating heat conduction layer and at least one second insulating heat conduction layer, wherein the thermal conductivity of the first insulating heat conduction layer is greater than the thermal conductivity of the insulating layer, and the thermal conductivity of the second insulating heat conduction layer is greater than the thermal conductivity of the insulating layer.

[0040] In one example, an insulating layer 11 is formed on the surface of at least one of the first substrate 10 and the second substrate 20. Exemplarily, the insulating layer 11 is formed on the surface of either the first substrate 10 or the second substrate 20, or on both the first substrate 10 and the second substrate 20. The insulating layer 11 is also the buried oxide layer (BOX) of the SOI substrate. Exemplarily, the material of the insulating layer can be an oxide (e.g., silicon dioxide) or other suitable materials. The process method for forming the insulating layer can be selected as needed, such as thermal oxidation or other suitable methods. The thickness of the formed insulating layer can be selected according to process requirements and is not specifically limited thereto. In this embodiment, the material of the insulating layer is silicon dioxide. There are various methods for forming the insulating layer and at least one thermally conductive structure located within the insulating layer on the surface of at least one of the first and second substrates; different methods will be described below.

[0041] In one example, such as Figure 4 and Figure 5 As shown, when an insulating layer 11 is formed on the surface of a substrate, for example, an insulating layer 11 is formed on a first substrate 10, at least one thermally conductive structure 12 is formed within the insulating layer 11. Each thermally conductive structure 12 includes at least one first insulating thermally conductive layer 13 and at least one second insulating thermally conductive layer 14. For example, one, two, three, or more thermally conductive structures 12 may be formed in the insulating layer 11. Each thermally conductive structure 12 may include two first insulating thermally conductive layers 13 and one second insulating thermally conductive layer 14, or each thermally conductive structure 12 may include one first insulating thermally conductive layer 13 and two second insulating thermally conductive layers 14; no specific limitation is made thereto. The step of forming at least one thermally conductive structure 12 within the insulating layer 11 includes:

[0042] First, the insulating layer 11 is etched to form at least one groove 110 penetrating the insulating layer. Specifically, a patterned photoresist layer is formed on the surface of the insulating layer 11, exposing the area and position corresponding to the thermally conductive structure. The insulating layer 11 is etched using the photoresist layer as a mask to form at least one groove 110, each groove 110 penetrating the insulating layer 11 and exposing a portion of the substrate surface. The photoresist layer is then removed. The etching of the insulating layer 11 can be performed using conventional etching processes such as dry etching, reactive ion etching (RIE), ion beam etching, and plasma etching.

[0043] Next, a first insulating and thermally conductive layer 13 is formed on the bottom and sidewalls of the groove 110. Specifically, a thermally conductive material is deposited in the groove 110 to form a first insulating and thermally conductive layer 13 covering the bottom and sidewalls of the groove 110. The thermally conductive material of the first insulating and thermally conductive layer 13 includes, but is not limited to, silicon nitride, boron nitride, or other suitable thermally conductive materials, and is not specifically limited thereto. The process method for forming the first insulating and thermally conductive layer 13 includes, but is not limited to, chemical vapor deposition (CVD), atomic layer deposition (ALD), or physical vapor deposition (PVD), and is not specifically limited thereto.

[0044] Finally, a second insulating thermally conductive layer 14 is formed on the first insulating thermally conductive layer 13 and fills the groove 110 to form a thermally conductive structure 12. Specifically, a thermally conductive material is filled into the groove 110, and the thermally conductive material fills the groove 110 and covers the first insulating thermally conductive layer 13 to form the second insulating thermally conductive layer 14. The thermally conductive material of the second insulating thermally conductive layer 14 is different from that of the first insulating thermally conductive layer 13. The thermally conductive material of the second insulating thermally conductive layer 14 includes, but is not limited to, silicon nitride, boron nitride, or other suitable thermally conductive materials, and is not specifically limited thereto. The process method for forming the second insulating thermally conductive layer 14 includes, but is not limited to, chemical vapor deposition (CVD), atomic layer deposition (ALD), or physical vapor deposition (PVD), and is not specifically limited thereto. The first insulating thermally conductive layer 13 and the second insulating thermally conductive layer 14 constitute the thermally conductive structure 12. Furthermore, after forming the first insulating thermally conductive layer 13 and the second insulating thermally conductive layer 14, the surfaces of the insulating layers are subjected to chemical mechanical polishing to remove excess thermally conductive material from the first and second insulating thermally conductive layers, thereby improving the reliability of the device. It should be noted that when the insulating layer is formed only on the second substrate, the method for forming the thermally conductive structure is the same as that on the first substrate, and will not be described in detail here.

[0045] In this design, the thermal conductivity of the first insulating thermally conductive layer 13 is greater than that of the insulating layer 11, and the thermal conductivity of the second insulating thermally conductive layer 14 is greater than that of the insulating layer 11. By setting the thermal conductivity of the first insulating thermally conductive layer 13 and the second insulating thermally conductive layer 14 to be greater than that of the insulating layer 11, the first and second insulating thermally conductive layers can conduct heat more efficiently during heat transfer, quickly dissipating the heat generated by the top semiconductor layer, etc., thus solving the heat dissipation bottleneck problem caused by the poor thermal conductivity of the insulating layer in conventional SOI substrates.

[0046] In one example, such as Figures 6 to 8 As shown, when an insulating layer 11 is formed on the surface of both the first substrate 10 and the surface of the second substrate 20, the step of forming at least one thermally conductive structure located in the insulating layer 11 includes:

[0047] First, the insulating layer 11 of the first substrate 10 is etched to form at least one first recess 111 penetrating the insulating layer 11, and the insulating layer 11 of the second substrate 20 is etched to form at least one second recess 112 penetrating the insulating layer 11, the positions of the first recess 111 and the second recess 112 corresponding to each other. Specifically, a patterned photoresist layer is formed on the surface of the insulating layer 11 of the first substrate 10, and the insulating layer 11 of the first substrate 10 is etched to form at least one first recess 111 penetrating the insulating layer 11 and exposing part of the surface of the first substrate 10, with the photoresist layer as a mask, and then the photoresist layer is removed; a patterned photoresist layer is formed on the surface of the insulating layer 11 of the second substrate 20, and the insulating layer 11 of the second substrate 20 is etched to form at least one second recess 112 penetrating the insulating layer 11 and exposing part of the surface of the second substrate 20, with the photoresist layer as a mask, and then the photoresist layer is removed; wherein the etching of the insulating layer 11 can be selected from conventional etching processes such as dry etching, reactive ion etching (RIE), ion beam etching, and plasma etching.

[0048] Second, the first insulating and heat-conducting layer 13 is formed on the bottom and sidewall of the first recess 111 and the second recess 112. Specifically, a heat-conducting material is deposited in the first recess 111 and the second recess 112 to form the first insulating and heat-conducting layer 13 covering the bottom and sidewall of the first recess 111 and the second recess 112, wherein the heat-conducting material of the first insulating and heat-conducting layer 13 includes but is not limited to silicon nitride, boron nitride, or other suitable heat-conducting materials, which are not specifically limited. The process method for forming the first insulating and heat-conducting layer 13 includes but is not limited to chemical vapor deposition (CVD), atomic layer deposition (ALD), or physical vapor deposition (PVD), etc., which are not specifically limited.

[0049] Finally, the second insulating and heat-conducting layer 14 is formed on the first insulating and heat-conducting layer 13 of the first groove 111 and the second groove 112, the second insulating and heat-conducting layer 14 in the first groove 111 fills the first groove 111, and the second insulating and heat-conducting layer 14 in the second groove 112 fills the second groove 112. Specifically, the heat-conducting material is filled in the first groove 111 and the second groove 112, the heat-conducting material in the first groove 111 fills the first groove 111 and covers the first insulating and heat-conducting layer 13 to form the second insulating and heat-conducting layer 14, and the heat-conducting material in the second groove 112 fills the second groove 112 and covers the first insulating and heat-conducting layer 13 to form the second insulating and heat-conducting layer 14, wherein the heat-conducting material of the second insulating and heat-conducting layer 14 is different from the heat-conducting material of the first insulating and heat-conducting layer 13, and the heat-conducting material of the second insulating and heat-conducting layer 14 includes but is not limited to silicon nitride, boron nitride or other suitable heat-conducting material, which is not limited specifically. The process method for forming the second insulating and heat-conducting layer 14 includes but is not limited to chemical vapor deposition (CVD), atomic layer deposition (ALD) or physical vapor deposition (PVD) method, which is not limited specifically. The first insulating and heat-conducting layer 13 and the second insulating and heat-conducting layer 14 of the first groove 111 constitute the first heat-conducting structure 121, and the first insulating and heat-conducting layer 13 and the second insulating and heat-conducting layer 14 of the second groove 112 constitute the second heat-conducting structure 122. In the subsequent bonding process, the side of the first substrate 10 formed with the insulating layer 11 and the side of the second substrate 20 formed with the insulating layer 11 are bonded, the first heat-conducting structure 121 and the second heat-conducting structure 122 correspond one by one, and the first heat-conducting structure 121 and the second heat-conducting structure 122 are connected to constitute the composite heat-conducting structure 18 after bonding.

[0050] In addition, after the first insulating and heat-conducting layer 13 and the second insulating and heat-conducting layer 14 are formed, the surface of the insulating layer 11 of the first substrate 10 and the second substrate 20 is also subjected to chemical mechanical polishing treatment to remove the excess heat-conducting material of the first insulating and heat-conducting layer and the second insulating and heat-conducting layer on the surface, thereby improving the reliability of the device.

[0051] In one example, as Figure 9 and Figure 10As shown, the heat-conducting structure can also be formed by first forming a layer of heat-conducting material and then forming an insulating layer. For example, at least one layer of first heat-conducting material 15 and at least one layer of second heat-conducting material 16 are formed on the surface of at least one of the first substrate 10 and the second substrate 20, such as on the surface of the first substrate 10 or the second substrate 20, or on the surface of both the first substrate 10 and the second substrate 20. Hereinafter, an example is described in which two layers of first heat-conducting material and one layer of second heat-conducting material are formed on the surface of the first substrate 10, with the second heat-conducting material layer being located between the two layers of first heat-conducting material:

[0052] First, the first heat-conducting material, the second heat-conducting material and the first heat-conducting material are sequentially deposited on the surface of the first substrate 10 to form two layers of first heat-conducting material 15 and a second heat-conducting material layer 16 located between the two layers of first heat-conducting material. For example, the first heat-conducting material and the second heat-conducting material include, but are not limited to, silicon nitride, boron nitride or other suitable heat-conducting materials, and the first heat-conducting material and the second heat-conducting material are different. The process method for forming the first heat-conducting material layer 15 and the second heat-conducting material layer 16 includes, but is not limited to, chemical vapor deposition (CVD), atomic layer deposition (ALD) or physical vapor deposition (PVD) and the like, and is not limited in particular.

[0053] Second, the first heat-conducting material layer 15 and the second heat-conducting material layer 16 are etched to form a groove penetrating through the first heat-conducting material layer 15 and the second heat-conducting material layer 16. Specifically, a patterned photoresist layer is formed on the surface of the first heat-conducting material layer 15, and the first heat-conducting material layer 15 and the second heat-conducting material layer 16 are etched with the photoresist layer as a mask to form at least one groove penetrating through the first heat-conducting material layer 15 and the second heat-conducting material layer 16 and exposing part of the surface of the first substrate 10, and then the photoresist layer is removed. The etching of the first heat-conducting material layer 15 and the second heat-conducting material layer 16 can be dry etching, reactive ion etching (RIE), ion beam etching, plasma etching and the like.

[0054] Finally, the groove is filled with an insulating material to form an insulating layer 11. For example, the material of the insulating layer 11 can be an oxide (such as silicon dioxide) or other suitable material. The process method for forming the insulating layer 11 can be selected as needed, such as thermal oxidation or other suitable methods, and is not limited in particular. In this embodiment, the material of the insulating layer 11 is silicon dioxide.

[0055] The remaining first thermal conductive material layer 15 forms a first insulating thermal conductive layer 13, and the remaining second thermal conductive material layer 16 forms a second insulating thermal conductive layer 14. The first insulating thermal conductive layer 13 and the second insulating thermal conductive layer 14 form a thermal conductive structure 12. The formed thermal conductive structure 12 can quickly conduct the heat of the subsequent top semiconductor layer to the base layer, improve the heat dissipation performance of the silicon-on-insulator substrate, and further improve the reliability of the device. In addition, the high mechanical strength of the thermal conductive structure also improves the hardness and rigidity of the silicon-on-insulator substrate, improves the Bow value, and avoids consuming more process time and material cost in subsequent processes. It should be noted that the method of forming a thermal conductive structure on the second substrate is the same as that on the first substrate, which will not be described in detail here.

[0056] Continuing, step S3 is performed to bond the first substrate and the second substrate, and the insulating layer and the thermal conductive structure are located between the bonded first substrate and the second substrate.

[0057] In one example, before bonding the first substrate 10 and the second substrate 20, the second substrate 20 is also subjected to ion implantation to form a weakened layer for guiding the fracture during the peeling process to form the top semiconductor layer 21. Specifically, to achieve controllable peeling of the second substrate for obtaining a high-quality top semiconductor layer, before bonding the first substrate 10 and the second substrate 20, the second substrate 20 is subjected to ion implantation treatment to form a weakened layer (also referred to as a "fracture layer" or a "hydrogen-rich layer") at a predetermined depth inside, which can induce controllable fracture of the substrate along a specific interface during subsequent heat treatment, thereby achieving precise transfer of the top semiconductor thin film to form the top semiconductor layer. For example, the ion implantation can use hydrogen ion implantation or hydrogen isotope ion implantation, which is not limited in particular. According to the process requirements, the ion implantation energy and dose are adjusted to control the depth and distribution characteristics of the weakened layer.

[0058] In one example, as shown in Figure 11 and Figure 15 When the insulating layer 11 is formed on the surface of a substrate, for example, the insulating layer 11 is formed on the first substrate 10, the first substrate 10 and the second substrate 20 are bonded, and through the bonding process, the first substrate 10 and the second substrate 20 form a firm connection at the interface, while ensuring that the insulating layer 11 and the thermal conductive structure 12 are located between the bonded first substrate 10 and the second substrate 20 to form the embedded functional layer of the subsequent SOI structure. For example, the bonding method can be direct bonding or indirect bonding, which is not limited in particular. In addition, as shown in Figure 13As shown, when an insulating layer 11 is formed on the surface of both the first substrate 10 and the second substrate 20, a first thermally conductive structure 121 is formed in the insulating layer 11 of the first substrate 10, and a second thermally conductive structure 122 is formed in the insulating layer 11 of the second substrate 20. During bonding, the side of the first substrate 10 with the insulating layer 11 and the side of the second substrate 20 with the insulating layer 11 are bonded together. The first thermally conductive structure 121 and the second thermally conductive structure 122 correspond one-to-one. After bonding, the first thermally conductive structure 121 and the second thermally conductive structure 122 are connected to form a composite thermally conductive structure 18.

[0059] Next, step S4 is performed to peel off a portion of the second substrate, leaving the remaining second substrate as the top semiconductor layer and the first substrate as the base layer of the silicon-on-insulator substrate.

[0060] In one example, such as Figure 12 , Figure 14 and Figure 16 As shown, after bonding the first substrate 10 and the second substrate 20, the second substrate 20 undergoes a peeling process to remove most of its material. Specifically, hydrogen ions are injected into the second substrate 20 before bonding to form a weakening layer, followed by a first-stage annealing at a certain temperature. This causes hydrogen to accumulate at the weakening layer and generate microbubbles, initiating controlled fracture along the layer. Under thermal stress, the cracks propagate along the weakening layer, achieving self-aligned peeling of the second substrate 20, thereby removing its main body and retaining only a thin layer of material near the bonding interface (i.e., the remaining second substrate). The remaining second substrate serves as the top semiconductor layer 21 of the silicon-on-insulator substrate, exhibiting good crystal integrity and thickness uniformity; while the first substrate 10 serves as the base layer 22 of the entire structure, providing mechanical support. Furthermore, after peeling, a second-stage annealing process can be performed at high temperature to enhance the interfacial bonding strength.

[0061] For example, after the second substrate 20 is stripped, the top semiconductor layer 21 is further subjected to chemical mechanical planarization. Planarizing the top semiconductor layer by chemical mechanical polishing (CMP) improves the reliability of the device, ultimately forming an SOI substrate comprising the top semiconductor layer 21, the insulating layer 11, the thermally conductive structure 12, and the base layer 22.

[0062] In the embodiment, the material of the insulation layer 11 is silicon dioxide, the thermal conductive material of the first insulation thermal conductive layer 13 is boron nitride (BN), which plays the role of insulation protection and interface transition; the thermal conductive material of the second insulation thermal conductive layer 14 is aluminum nitride (ALN), which serves as the main thermal conductive channel. Both BN and ALN are high thermal conductive and high insulation materials, and the thermal conductive structure composed of BN and ALN can have higher thermal conductivity, which can better improve the heat dissipation effect of the SOI substrate. The thermal conductivity of the thermal conductive structure is about 200-300 times of that of silicon dioxide. In addition, BN itself has excellent mechanical properties: the combination characteristics of strong covalent bonds in the crystal structure of BN make it have much higher hardness and Young's modulus (stiffness) than monocrystalline silicon, so the hardness and stiffness of the SOI substrate can be improved, so that the hardness of the SOI substrate formed reaches 6 times of that of monocrystalline silicon, and the stiffness reaches 9 times of that of monocrystalline silicon, solving the problem of easy breakage and poor deformation resistance of the conventional SOI substrate due to the weak mechanical properties of the insulation layer (such as silicon dioxide), and improving the Bow value of the SOI substrate. In other examples, the thermal conductive material of the first insulation thermal conductive layer 13 can also be aluminum nitride, and the thermal conductive material of the second insulation thermal conductive layer 14 can also be boron nitride, which is not limited in particular.

[0063] In some examples, the insulation layer 11 can also include at least one first insulation thermal conductive layer 13 and at least one second insulation thermal conductive layer 14. Optionally, the insulation layer 11 can be made synchronously with the thermal conductive structure, that is, the insulation layer 11 and the thermal conductive structure are composed of at least one first insulation thermal conductive layer 13 and at least one second insulation thermal conductive layer 14, or can be made asynchronously.

[0064] It is worth mentioning that the above steps are only examples, and the order of the above steps can also be adjusted without conflict.

[0065] So far, the process steps of the preparation method of the silicon-on-insulator substrate according to the embodiment of the present application have been completed. It can be understood that the silicon-on-insulator substrate preparation method of the present embodiment not only includes the above steps, but also can include other required steps before, during or after the above steps, which are all included in the scope of the preparation method of the present embodiment.

[0066] In summary, the preparation method of the silicon-on-insulator substrate of the present application embeds at least one thermal conductive structure in the insulation layer of the silicon-on-insulator substrate, the thermal conductive structure is composed of a first insulation thermal conductive layer and a second insulation thermal conductive layer, and both the first insulation thermal conductive layer and the second insulation thermal conductive layer are high thermal conductivity and high electrical insulation materials. Therefore, the thermal conductive structure can rapidly conduct the heat of the top semiconductor layer to the base layer, improve the heat dissipation performance of the silicon-on-insulator substrate, and further improve the reliability of the device. In addition, the high mechanical strength of the thermal conductive structure also improves the hardness and stiffness of the silicon-on-insulator substrate, improves the Bow value, and avoids wasting more process time and material cost in subsequent processes.

[0067] Example 2

[0068] This application also provides a silicon-on-insulator substrate, which can be prepared by the method described in the first embodiment above.

[0069] The following reference Figures 3 to 16 The silicon-on-insulator substrates in the embodiments of this application will be explained and described, wherein structures identical to those in the aforementioned Embodiment 1 will not be described in detail here.

[0070] Specifically, such as Figures 3 to 16 As shown, the silicon-on-insulator (SiI) substrate of this application includes: a base layer 22; an insulating layer 11 located on the base layer 22; at least one thermally conductive structure 12 located within the insulating layer 11, each thermally conductive structure 12 including at least one first insulating thermally conductive layer 13 and at least one second insulating thermally conductive layer 14, wherein the thermal conductivity of the first insulating thermally conductive layer 13 is greater than that of the insulating layer 11, and the thermal conductivity of the second insulating thermally conductive layer 14 is greater than that of the insulating layer 11; and a top semiconductor layer 21 located on the thermally conductive structure 12. By embedding thermally conductive structures within the insulating layer of the SiI substrate, heat from the top semiconductor layer can be rapidly conducted to the base layer, improving the heat dissipation performance of the SiI substrate and thus enhancing the reliability of the device. Furthermore, the high mechanical strength of the thermally conductive structures also improves the hardness and stiffness of the SiI substrate, enhancing its Bow value and avoiding the need for more processing time and material costs in subsequent processes.

[0071] For example, the first insulating thermally conductive layer 13 and the second insulating thermally conductive layer 14 are made of different thermally conductive materials, wherein the material of the first insulating thermally conductive layer 13 is boron nitride or aluminum nitride, and the material of the second insulating thermally conductive layer 14 is boron nitride or aluminum nitride.

[0072] In some examples, the insulating layer 11 may also include at least one first insulating thermally conductive layer 13 and at least one second insulating thermally conductive layer 14. Optionally, the insulating layer 11 may be manufactured simultaneously with the thermally conductive structure, that is, the insulating layer 11 and the thermally conductive structure are composed of at least one first insulating thermally conductive layer 13 and at least one second insulating thermally conductive layer 14, or they may be manufactured separately.

[0073] For example, the base layer 22 is a silicon substrate or a silicon carbide substrate, wherein when the base layer is a silicon carbide substrate, it can have a higher heat dissipation effect.

[0074] Exemplarily, the heat-conducting structure 12 penetrates the insulating layer 11. Specifically, one end of the heat-conducting structure 12 is in contact with the surface of the base layer 22, and the other end is in contact with the surface of the top semiconductor layer 21. The penetrating heat-conducting structure quickly conducts heat from the active region of the device (i.e., the region formed subsequently above the top semiconductor layer) to the base layer, significantly reduces the junction temperature when the device is working, and improves the power density and reliability. At the same time, the structure can be designed in an array arrangement in the lateral distribution, taking into account the electrical isolation and thermal performance, and is suitable for application scenarios of high-frequency and high-power semiconductor devices.

[0075] The silicon-on-insulator substrate provided by the present application embeds at least one heat-conducting structure in the insulating layer in the silicon-on-insulator substrate, the heat-conducting structure is composed of a first insulating heat-conducting layer and a second insulating heat-conducting layer, and the first insulating heat-conducting layer and the second insulating heat-conducting layer are both materials with high thermal conductivity and high electrical insulation. Therefore, the heat-conducting structure can quickly conduct heat from the top semiconductor layer to the base layer, improve the heat dissipation performance of the silicon-on-insulator substrate, and further improve the reliability of the device. In addition, the high mechanical strength of the heat-conducting structure also improves the hardness and stiffness of the silicon-on-insulator substrate, improves its Bow value, and avoids wasting more process time and material cost in subsequent processes.

[0076] Although a number of embodiments have been described herein, it is understood that the skilled person might conceive many other modifications and embodiments, which would all fall within the spirit and scope of the inventive concept disclosed. More particularly, various modifications and changes in the arrangement and / or composition of the subject matter can be made within the scope of the present disclosure, the accompanying drawings, and the appended claims. In addition to modifications and changes in the composition and / or arrangement, the use of alternative means will be apparent to those skilled in the art.

Claims

1. A method for fabricating a silicon-on-insulator substrate, characterized in that, include: Provide a first substrate and a second substrate; An insulating layer and at least one thermally conductive structure are formed on the surface of at least one of the first substrate and the second substrate. Each thermally conductive structure includes at least one first insulating thermally conductive layer and at least one second insulating thermally conductive layer. The first insulating thermally conductive layer and the second insulating thermally conductive layer are made of different thermally conductive materials. The material of the first insulating thermally conductive layer or the material of the second insulating thermally conductive layer is boron nitride. The thermal conductivity of the first insulating thermally conductive layer is greater than that of the insulating layer, and the thermal conductivity of the second insulating thermally conductive layer is greater than that of the insulating layer. The first substrate and the second substrate are bonded together, and the insulating layer and the thermally conductive structure are located between the bonded first substrate and the second substrate; The second substrate is peeled off to remove a portion of the second substrate, and the remaining second substrate serves as the top semiconductor layer, while the first substrate serves as the base layer of the silicon-on-insulator substrate.

2. The method for preparing a silicon-on-insulator substrate as described in claim 1, characterized in that, A method for forming at least one thermally conductive structure located in the insulating layer includes: The insulating layer is etched to form at least one groove penetrating the insulating layer; A first insulating and thermally conductive layer is formed at the bottom and sidewalls of the groove; A second insulating and thermally conductive layer is formed on the first insulating and thermally conductive layer and the groove is filled to form the thermally conductive structure.

3. The method for fabricating a silicon-on-insulator substrate as described in claim 1, characterized in that, When the insulating layer is formed on the surface of both the first substrate and the surface of the second substrate, a method for forming at least one thermally conductive structure located in the insulating layer includes: The insulating layer of the first substrate is etched to form at least one first groove penetrating the insulating layer therethrough, and the insulating layer of the second substrate is etched to form at least one second groove penetrating the insulating layer therethrough, wherein the positions of the first groove and the second groove are corresponding. A first insulating and thermally conductive layer is formed on the bottom and sidewalls of both the first and second grooves; A second insulating and thermally conductive layer is formed on the first insulating and thermally conductive layer of both the first groove and the second groove. The second insulating and thermally conductive layer in the first groove fills the first groove, and the second insulating and thermally conductive layer in the second groove fills the second groove. Wherein, the first insulating and heat-conducting layer and the second insulating and heat-conducting layer of the first groove constitute a first heat-conducting structure, and the first insulating and heat-conducting layer and the second insulating and heat-conducting layer of the second groove constitute a second heat-conducting structure. The bonding of the first substrate and the second substrate includes: The first substrate with an insulating layer is bonded to the second substrate with the insulating layer, wherein the first thermally conductive structure and the second thermally conductive structure correspond one-to-one, and after bonding, the first thermally conductive structure and the second thermally conductive structure are connected to form a composite thermally conductive structure.

4. The method for preparing a silicon-on-insulator substrate as described in claim 1, characterized in that, An insulating layer and at least one thermally conductive structure located within the insulating layer are formed on the surface of at least one of the first and second substrates, including: At least one first thermally conductive material layer and at least one second thermally conductive material layer are formed on the surface of at least one of the first substrate and the second substrate; Etch the first thermally conductive material layer and the second thermally conductive material layer to form a groove penetrating the first thermally conductive material layer and the second thermally conductive material layer; The groove is filled with insulating material to form the insulating layer; The remaining first thermally conductive material layer constitutes the first insulating thermally conductive layer, and the remaining second thermally conductive material layer constitutes the second insulating thermally conductive layer. The first insulating thermally conductive layer and the second insulating thermally conductive layer constitute the thermally conductive structure.

5. The method for preparing a silicon-on-insulator substrate according to any one of claims 1-4, characterized in that, The material of the first insulating thermally conductive layer or the material of the second insulating thermally conductive layer is aluminum nitride; and / or The insulating layer includes at least one first insulating and thermally conductive layer and at least one second insulating and thermally conductive layer.

6. The method for fabricating a silicon-on-insulator substrate as described in claim 1, characterized in that, Before bonding the first substrate and the second substrate, the method further includes: ion implantation of the second substrate to form a weakening layer, the weakening layer being used to guide breakage during the peeling process to form the top semiconductor layer; and / or After the second substrate is stripped, the process further includes: performing a chemical mechanical planarization process on the top semiconductor layer.

7. A silicon-on-insulator substrate, characterized in that, include: basal layer; An insulating layer, the insulating layer being located on the substrate layer; At least one thermally conductive structure is located within the insulating layer. Each thermally conductive structure includes at least one first insulating thermally conductive layer and at least one second insulating thermally conductive layer. The first insulating thermally conductive layer and the second insulating thermally conductive layer are made of different thermally conductive materials. The material of either the first insulating thermally conductive layer or the second insulating thermally conductive layer is boron nitride. The thermal conductivity of the first insulating thermally conductive layer is greater than that of the insulating layer, and the thermal conductivity of the second insulating thermally conductive layer is greater than that of the insulating layer. A top semiconductor layer is located on the thermally conductive structure.

8. The silicon-on-insulator substrate as claimed in claim 7, characterized in that, The material of the first insulating thermally conductive layer or the material of the second insulating thermally conductive layer is aluminum nitride; and / or The insulating layer includes at least one first insulating and thermally conductive layer and at least one second insulating and thermally conductive layer.

9. The silicon-on-insulator substrate as claimed in claim 7, characterized in that, The substrate layer is a silicon substrate or a silicon carbide substrate.

10. The silicon-on-insulator substrate as claimed in claim 7, characterized in that, The thermally conductive structure penetrates the insulating layer, with one end of the thermally conductive structure connected to the base layer and the other end connected to the top semiconductor layer.

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