Semiconductor structure and method of manufacturing the same

Abstract

The embodiment of the application provides a semiconductor structure and a preparation method thereof, and relates to the technical field of integrated photon devices. The semiconductor structure comprises a silicon substrate layer; a lithium niobate film layer formed on one side of the silicon substrate layer along a first direction; and a stress compensation layer formed between the silicon substrate layer and the lithium niobate film layer along the first direction, the stress compensation layer being used for partially or totally offsetting residual internal stress of the silicon substrate layer and the lithium niobate film layer. By introducing the stress compensation layer with preset initial internal stress between the silicon substrate layer and the lithium niobate film layer, the neutral axis position and the equivalent bending stiffness in the laminated structure are regulated, the equivalent bending moment in the annealing stage is offset, and then the residual internal stress of the obtained lithium niobate film-silicon substrate composite structure is reduced or eliminated, the warping of the lithium niobate film-silicon substrate composite structure is improved, the lattice distortion of the lithium niobate is improved, and thus the yield of the lithium niobate film-silicon substrate composite structure is improved.

Description

Technical Field

[0001] This application relates to the field of integrated photonic device technology, and in particular to a semiconductor structure and its fabrication method. Background Technology

[0002] Lithium niobate on insulator (LNOI) technology is a key platform for developing high-performance integrated photonic chips. Its manufacturing process typically involves heterogeneous integration of lithium niobate films prepared by "ion slicing" technology with silicon substrates through room temperature bonding and high-temperature annealing (usually 200-400℃).

[0003] However, due to the significant difference in the coefficients of thermal expansion between lithium niobate and silicon, the lithium niobate-silicon heterobonded structure will warp after high-temperature annealing, resulting in a decrease in the yield of the lithium niobate-silicon heterobonded structure. Summary of the Invention

[0004] This application provides a semiconductor structure and its fabrication method to improve the warping of lithium niobate thin film-silicon substrate composite structures and the lattice distortion of lithium niobate, thereby improving the yield of lithium niobate thin film-silicon substrate composite structures.

[0005] In a first aspect, embodiments of this application provide a semiconductor structure, including...

[0006] Silicon substrate;

[0007] A lithium niobate thin film layer, wherein the lithium niobate thin film layer is formed along a first direction on one side of the silicon substrate layer;

[0008] A stress compensation layer is formed along the first direction between the silicon substrate layer and the lithium niobate thin film layer, the stress compensation layer being used to partially or completely offset the residual internal stress of the silicon substrate layer and the lithium niobate thin film layer.

[0009] In one possible implementation, the material of the stress compensation layer includes at least one of silicon dioxide, silicon nitride, and metal.

[0010] In one possible implementation, the stress compensation layer comprises a plurality of sequentially stacked sub-compensation layers along the first direction, each of the sub-compensation layers being made of at least one of silicon dioxide, silicon nitride, and a metal.

[0011] In one possible implementation, the sum of the residual internal stress of the silicon substrate layer and the residual internal stress of the lithium niobate thin film layer is no greater than 50 MPa.

[0012] In one possible implementation, the thickness of the silicon substrate layer along the first direction ranges from 100 μm to 1000 μm;

[0013] And / or, the thickness of the lithium niobate thin film layer along the first direction ranges from 100 nm to 1000 nm;

[0014] And / or, the thickness of the stress compensation layer along the first direction ranges from 10 nm to 1000 nm.

[0015] Secondly, embodiments of this application provide a method for fabricating a semiconductor structure, including,

[0016] A silicon substrate and a lithium niobate wafer are provided. A separation layer is formed in the lithium niobate wafer by ion implantation. A lithium niobate thin film layer and a lithium niobate residual layer are formed on both sides of the separation layer, respectively.

[0017] A stress compensation layer is formed on the silicon substrate, and / or the stress compensation layer is formed on the lithium niobate wafer; the stress compensation layer has an initial internal stress.

[0018] A lithium niobate wafer-silicon substrate bonding structure is formed, wherein the stress compensation layer is located between the silicon substrate and the lithium niobate wafer, or the stress compensation layer is located on the side of the lithium niobate wafer facing away from the silicon substrate;

[0019] The residual lithium niobate layer is removed by annealing.

[0020] In one possible implementation, forming the stress compensation layer specifically includes forming the stress compensation layer on one side of the silicon substrate;

[0021] The formation of the lithium niobate wafer-silicon substrate bonding structure specifically includes,

[0022] The silicon substrate and the lithium niobate wafer are bonded together with the stress compensation layer and the lithium niobate thin film layer facing each other.

[0023] In one possible implementation, forming the stress compensation layer specifically includes forming a first sub-compensation layer on one side of the silicon substrate and forming a second sub-compensation layer on the side of the lithium niobate thin film layer opposite to the lithium niobate residual layer; the first sub-compensation layer and the second sub-compensation layer form the stress compensation layer.

[0024] The formation of the lithium niobate wafer-silicon substrate bonding structure specifically includes,

[0025] The silicon substrate and the lithium niobate wafer are bonded together with the first sub-compensation layer and the second sub-compensation layer facing each other.

[0026] In one possible implementation, forming the stress compensation layer specifically includes forming a first coordination compensation layer on one side of the silicon substrate and forming a second coordination compensation layer on the side of the lithium niobate residual layer opposite to the lithium niobate thin film layer; the first coordination compensation layer and the second coordination compensation layer respectively serve as the stress compensation layer.

[0027] The formation of the lithium niobate wafer-silicon substrate bonding structure specifically includes,

[0028] The silicon substrate and the lithium niobate wafer are bonded together with the first compensation layer and the lithium niobate thin film layer facing each other.

[0029] In one possible implementation, forming the stress compensation layer specifically includes forming the stress compensation layer on the side of the lithium niobate thin film layer opposite to the lithium niobate residual layer.

[0030] The formation of the lithium niobate wafer-silicon substrate bonding structure specifically includes,

[0031] The silicon substrate and the lithium niobate wafer are bonded together with the silicon substrate and the stress compensation layer facing each other.

[0032] In one possible implementation, forming the stress compensation layer specifically includes forming the stress compensation layer on the side of the lithium niobate residue layer opposite to the lithium niobate thin film layer.

[0033] The formation of the lithium niobate wafer-silicon substrate bonding structure specifically includes,

[0034] The silicon substrate and the lithium niobate wafer are bonded together with the silicon substrate and the lithium niobate thin film layer facing each other.

[0035] In one possible implementation, the material of the stress compensation layer includes at least one of silicon dioxide, silicon nitride, and metal.

[0036] In one possible implementation, the initial internal stress includes at least one of compressive stress and tensile stress.

[0037] In one possible implementation, the stress compensation layer has a first thickness dimension along the bonding direction of the silicon substrate and the lithium niobate wafer; the product of the initial internal stress and the first thickness dimension ranges from 5 N / m to 800 N / m.

[0038] In one possible implementation, the absolute value of the initial internal stress ranges from 50 MPa to 1.5 GPa;

[0039] And / or, the first thickness dimension ranges from 10nm to 1000nm.

[0040] The semiconductor structure and its fabrication method provided in this application have a preset initial internal stress in the stress compensation layer. After annealing, the initial internal stress of the stress compensation layer in the lithium niobate wafer-silicon substrate bonding structure containing the stress compensation layer can offset the residual internal stress of the silicon substrate layer and the lithium niobate thin film layer. This reduces or even eliminates the residual internal stress of the obtained lithium niobate thin film-silicon substrate composite structure, thereby improving the warping of the lithium niobate thin film-silicon substrate composite structure and the lattice distortion of lithium niobate, thus improving the yield of the lithium niobate thin film-silicon substrate composite structure. Attached Figure Description

[0041] 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.

[0042] Figure 1 A schematic diagram of a first lithium niobate thin film-silicon substrate composite structure provided in some embodiments of this application;

[0043] Figure 2 This is a process flow diagram for preparing lithium niobate thin films on silicon substrates in related technologies.

[0044] Figure 3 This is a schematic diagram of a lithium niobate thin film-silicon substrate composite structure prepared in related technologies.

[0045] Figure 4 This is a process flow diagram for the first method of preparing a lithium niobate thin film-silicon substrate composite structure, provided in some embodiments of this application.

[0046] Figure 5 This is a process flow diagram for a second method of preparing a lithium niobate thin film-silicon substrate composite structure, provided in some embodiments of this application.

[0047] Figure 6 This is a schematic diagram of a second lithium niobate thin film-silicon substrate composite structure provided in some embodiments of this application;

[0048] Figure 7 A schematic diagram of a third lithium niobate thin film-silicon substrate composite structure provided in some embodiments of this application;

[0049] Figure 8 A flowchart illustrating the method for preparing a lithium niobate thin film-silicon substrate composite structure provided in some embodiments of this application;

[0050] Figure 9 This is a process flow diagram for the third method of preparing a lithium niobate thin film-silicon substrate composite structure, provided in some embodiments of this application.

[0051] Figure 10A schematic diagram of a fourth lithium niobate thin film-silicon substrate composite structure provided in some embodiments of this application;

[0052] Figure 11 This is a process flow diagram for the fourth method of preparing a lithium niobate thin film-silicon substrate composite structure, provided in some embodiments of this application.

[0053] Figure 12 This is a process flow diagram for the fifth method of preparing a lithium niobate thin film-silicon substrate composite structure, provided in some embodiments of this application.

[0054] Figure 13 This is a process flow diagram for the sixth method of preparing a lithium niobate thin film-silicon substrate composite structure, provided in some embodiments of this application.

[0055] Figure 14 This is a process flow diagram for the seventh method of preparing a lithium niobate thin film-silicon substrate composite structure, provided in some embodiments of this application.

[0056] Figure 15 This is a comparison chart of the bending (BOW) values ​​of the lithium niobate thin film-silicon substrate composite structures obtained in Examples 1 to 6, Comparative Example 1, and Comparative Example 2.

[0057] Explanation of reference numerals in the attached figures:

[0058] 100, silicon substrate; 200, silicon substrate layer;

[0059] 300. Lithium niobate wafer; 310. Lithium niobate thin film layer; 320. Separation layer; 330. Lithium niobate residue layer;

[0060] 400, Stress compensation layer; 401, First sub-compensation layer; 402, Second sub-compensation layer; 403, Third sub-compensation layer; 404, Intermediate compensation layer; 410, First matching compensation layer; 420, Second matching compensation layer.

[0061] 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

[0062] 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.

[0063] Lithium niobate on insulator (LNOI) technology is a key platform for developing high-performance integrated photonic chips. Its manufacturing process typically involves heterogeneous integration of lithium niobate films prepared by "ion slicing" technology with silicon substrates through room temperature bonding and high-temperature annealing (usually 200-400℃).

[0064] However, due to the significant difference in the coefficients of thermal expansion between lithium niobate and silicon, the lithium niobate-silicon heterobonded structure will warp after high-temperature annealing, resulting in a decrease in the yield of the lithium niobate-silicon heterobonded structure.

[0065] The semiconductor structure and its fabrication method provided in this application have a preset initial internal stress in the stress compensation layer. After annealing, the initial internal stress of the stress compensation layer in the lithium niobate wafer-silicon substrate bonding structure containing the stress compensation layer can offset the residual internal stress of the silicon substrate layer and the lithium niobate thin film layer, thereby reducing or even eliminating the residual internal stress of the obtained lithium niobate thin film-silicon substrate composite structure. This can improve the warping of the lithium niobate thin film-silicon substrate composite structure and the lattice distortion of lithium niobate, thereby improving the yield of the lithium niobate thin film-silicon substrate composite structure.

[0066] 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.

[0067] Firstly, see [the following] Figure 1 As shown in the embodiment of this application, a semiconductor structure is provided, which includes a silicon substrate layer 200, a lithium niobate thin film layer 310, and a stress compensation layer 400. The stress compensation layer 400 is located on one side of the silicon substrate layer 200, and the lithium niobate thin film layer 310 is located on the side of the stress compensation layer 400 opposite to the silicon substrate layer 200. The silicon substrate layer 200, the lithium niobate thin film layer 310, and the stress compensation layer 400 are stacked sequentially along a first direction X. Exemplarily, the first direction X can be the thickness direction of the silicon substrate layer 200.

[0068] See Figure 2As shown, the conventional method for fabricating a lithium niobate thin film layer 310 on a silicon substrate 200 typically involves first ion implantation of a lithium niobate wafer 300 to form a separation layer 320 within the wafer 300. A lithium niobate residue layer 330 and a lithium niobate thin film layer 310 are then formed on either side of the separation layer 320. The lithium niobate thin film layer 310 is then bonded to the silicon substrate 100 to form a lithium niobate wafer-silicon substrate bonding structure. The lithium niobate residue layer 330 is then removed via an annealing process to form a lithium niobate thin film-silicon substrate composite structure, thereby transferring the lithium niobate thin film layer 310 onto the silicon substrate 200, thus completing the fabrication of the lithium niobate thin film layer 310 on the silicon substrate 200.

[0069] However, during the annealing process, due to the significant difference in the thermal expansion coefficients of the silicon substrate layer 200 and the lithium niobate thin film layer 310, the silicon substrate layer 200 shrinks more slowly during the cooling process after annealing, while the lithium niobate thin film layer 310 shrinks more rapidly. This results in the lithium niobate thin film layer 310 being subjected to tensile stress, while the silicon substrate layer 200 is subjected to compressive stress. Consequently, the lithium niobate thin film-silicon substrate composite structure exhibits substantial residual internal stress. (See [link to relevant documentation]). Figure 3 As shown, macroscopically, this can easily lead to warping in the lithium niobate thin film-silicon substrate composite structure, and microscopically, it can easily lead to lattice distortion of lithium niobate, thereby causing a decrease in the yield of the lithium niobate thin film-silicon substrate composite structure.

[0070] The stress compensation layer 400 of this application embodiment is used to at least partially offset the residual internal stress of the silicon substrate layer 200 and the lithium niobate thin film layer 310. That is, in some cases, the stress compensation layer 400 can partially offset the residual internal stress of the silicon substrate layer 200 and the lithium niobate thin film layer 310, and in some cases, the stress compensation layer 400 can completely offset the residual internal stress of the silicon substrate layer 200 and the lithium niobate thin film layer 310.

[0071] For example, see Figure 4 As shown, before forming the lithium niobate wafer-silicon substrate bonding structure, a stress compensation layer 400 is first formed on the side of the lithium niobate thin film layer 310 away from the lithium niobate residual layer 330. Then, the lithium niobate wafer-silicon substrate bonding structure is formed by bonding process with the stress compensation layer 400 and the silicon substrate layer 200 facing each other.

[0072] Another example is seen in [reference 1]. Figure 5 As shown, before forming the lithium niobate wafer-silicon substrate bonding structure, a stress compensation layer 400 is first formed on one side of the silicon substrate 100. Then, the lithium niobate wafer-silicon substrate bonding structure is formed by bonding process with the stress compensation layer 400 and the lithium niobate thin film layer 310 facing each other.

[0073] It should be noted that, see Figure 1 , Figure 4 and Figure 5 As shown, the stress compensation layer 400 formed has a preset initial internal stress. After annealing, the initial internal stress of the lithium niobate wafer-silicon substrate bonding structure containing the stress compensation layer 400 can offset the residual internal stress of the silicon substrate layer 200 and the lithium niobate thin film layer 310, thereby reducing or even eliminating the residual internal stress of the lithium niobate thin film-silicon substrate composite structure. This can improve the warping of the lithium niobate thin film-silicon substrate composite structure and improve the lattice distortion of lithium niobate, thereby improving the yield of the lithium niobate thin film-silicon substrate composite structure.

[0074] It is understandable that the warping of the lithium niobate thin film-silicon substrate composite structure is mainly caused by the driving bending moment generated by the residual internal stress. However, the embodiments of this application pre-set an initial internal stress in the stress compensation layer 400, so that the initial internal stress can generate a compensation bending moment. The compensation bending moment can offset part or all of the driving bending moment, thereby reducing or even eliminating the warping of the lithium niobate thin film-silicon substrate composite structure from the root.

[0075] In some embodiments of this application, the stress compensation layer 400 is made of at least one of silicon dioxide, silicon nitride, and metal.

[0076] For example, the stress compensation layer 400 is made of silicon dioxide, silicon nitride, or metal.

[0077] As another example, the stress compensation layer 400 is made of two of silicon dioxide, silicon nitride, and metal.

[0078] As another example, the stress compensation layer 400 is made of silicon dioxide, silicon nitride, and metal.

[0079] The stress compensation layer 400 of this application embodiment can be formed on one side of the silicon substrate layer 200 or on the side of the lithium niobate thin film layer 310 away from the lithium niobate residue layer 330 by processes such as plasma enhanced chemical vapor deposition (PECVD) and magnetron sputtering.

[0080] When the material of the stress compensation layer 400 includes a metal, for example, the metal may be titanium or tungsten, etc., without particular limitation.

[0081] In some embodiments of this application, the stress compensation layer 400 includes a plurality of sub-compensation layers, and the plurality of sub-compensation layers are stacked sequentially along a first direction X.

[0082] For example, see Figure 6As shown, the stress compensation layer 400 includes a first sub-compensation layer 401 and a second sub-compensation layer 402. The first sub-compensation layer 401 is formed on one side of the silicon substrate layer 200 along the first direction X, the second sub-compensation layer 402 is formed on the side of the first sub-compensation layer 401 opposite to the second sub-compensation layer 402, and a lithium niobate thin film layer 310 is formed on the side of the second sub-compensation layer 402 opposite to the first sub-compensation layer 401.

[0083] Another example is seen in [reference 1]. Figure 7 As shown, the stress compensation layer 400 includes a first sub-compensation layer 401, a second sub-compensation layer 402, and a third sub-compensation layer 403. The first sub-compensation layer 401 is formed on one side of the silicon substrate layer 200 along the first direction X. The second sub-compensation layer 402 is formed on the side of the first sub-compensation layer 401 opposite to the second sub-compensation layer 402. The third sub-compensation layer 403 is formed on the side of the second sub-compensation layer 402 opposite to the first sub-compensation layer 401. A lithium niobate thin film layer 310 is formed on the side of the third sub-compensation layer 403 opposite to the second sub-compensation layer 402.

[0084] This embodiment of the application sets the stress compensation layer 400 to include multiple sub-compensation layers. This allows for the pre-setting of internal stresses of different magnitudes and directions within these sub-compensation layers during the formation of the stress compensation layer 400. The pre-set internal stresses in these multiple sub-compensation layers collectively form the initial internal stress of the stress compensation layer 400. This makes the design of the initial internal stress more flexible, thereby improving the effect of the initial internal stress in offsetting residual internal stress, further reducing or even eliminating residual internal stress. Here, the direction of the internal stress refers to whether the internal stress is tensile or compressive.

[0085] Furthermore, the material of each sub-compensation layer includes at least one of silicon dioxide, silicon nitride, and metal.

[0086] For example, the material of each sub-compensation layer is silicon dioxide, silicon nitride, or metal.

[0087] As another example, the material of each sub-compensation layer is two of silicon dioxide, silicon nitride, and metal.

[0088] As another example, the material of each sub-compensation layer is silicon dioxide, silicon nitride, and metal.

[0089] When the material of the sub-compensation layer includes metal, for example, the metal can be titanium or tungsten, etc., without particular limitation.

[0090] In some embodiments of this application, the sum of the residual internal stress of the silicon substrate layer 200 and the residual internal stress of the lithium niobate thin film layer 310 is not greater than 50 MPa, that is, the residual internal stress of the lithium niobate thin film-silicon substrate composite structure is not greater than 50 MPa.

[0091] For example, the residual internal stress of the lithium niobate thin film-silicon substrate composite structure without the stress compensation layer 400 after annealing is greater than or equal to 50 MPa, while the residual internal stress of the lithium niobate thin film-silicon substrate composite structure with the stress compensation layer 400 after annealing is not greater than 50 MPa.

[0092] In some embodiments of this application, the thickness of the silicon substrate layer 200 along the first direction X ranges from 100 μm to 1000 μm.

[0093] For example, the thickness of the silicon substrate layer 200 along the first direction X can be 100μm, 110μm, 130μm, 150μm, 180μm, 210μm, 260μm, 270μm, 300μm, 330μm, 340μm, 380μm, 420μm, 470μm, 490μm, 550μm, 590μm, 600μm, 604μm, 670μm, 720μm, 740μm, 770μm, 810μm, 860μm, 880μm, 910μm, 930μm, 970μm, 990μm or 1000μm, and there is no particular limitation thereto.

[0094] Furthermore, the thickness of the lithium niobate thin film layer 310 along the first direction X ranges from 100 nm to 1000 nm.

[0095] For example, the thickness of the lithium niobate thin film layer 310 along the first direction X can be 100nm, 110nm, 130nm, 150nm, 180nm, 210nm, 260nm, 270nm, 300nm, 330nm, 340nm, 380nm, 420nm, 470nm, 490nm, 550nm, 590nm, 600nm, 604nm, 670nm, 720nm, 740nm, 770nm, 810nm, 860nm, 880nm, 910nm, 930nm, 970nm, 990nm, or 1000nm, and there is no particular limitation thereto.

[0096] Furthermore, the thickness of the stress compensation layer 400 along the first direction X ranges from 10 nm to 1000 nm.

[0097] For example, the thickness of the stress compensation layer 400 along the first direction X can be 10nm, 50nm, 80nm, 100nm, 140nm, 170nm, 210nm, 280nm, 320nm, 360nm, 390nm, 440nm, 470nm, 480nm, 500nm, 520nm, 570nm, 590nm, 630nm, 670nm, 740nm, 770nm, 780nm, 810nm, 880nm, 890nm, 910nm, 970nm, 990nm, or 1000nm, without any particular limitation.

[0098] Secondly, this application provides a method for preparing a semiconductor structure, which can be used to prepare the above-mentioned semiconductor structure.

[0099] See Figure 8 As shown, the method for fabricating a semiconductor structure includes the following steps:

[0100] Step S100: Provide a silicon substrate and a lithium niobate wafer, and form a separation layer in the lithium niobate wafer by ion implantation. A lithium niobate thin film layer and a lithium niobate residual layer are formed on both sides of the separation layer, respectively.

[0101] Step S200: Form a stress compensation layer, which is formed on a silicon substrate and / or on a lithium niobate wafer; the stress compensation layer has initial internal stress.

[0102] In this step, the stress compensation layer 400 can be formed by processes such as plasma-enhanced chemical vapor deposition (PECVD) or magnetron sputtering, and there are no particular limitations on this.

[0103] It is understandable that, when forming the stress compensation layer 400, the initial internal stress can be preset in the stress compensation layer 400 by precisely controlling the process parameters.

[0104] Step S300: Form a lithium niobate wafer-silicon substrate bonding structure, wherein the stress compensation layer is located between the silicon substrate and the lithium niobate wafer, or the stress compensation layer is located on the side of the lithium niobate wafer away from the silicon substrate.

[0105] Step S400: Remove the residual lithium niobate layer using an annealing process.

[0106] In this step, the lithium niobate wafer-silicon substrate bonding structure is annealed to vaporize the ions injected into the separation layer 320, thereby achieving the effect of stripping the lithium niobate residual layer 330 and transferring the lithium niobate thin film layer 310 onto the silicon substrate 100, thus obtaining the lithium niobate thin film-silicon substrate composite structure.

[0107] It is worth mentioning that, since the initial internal stress is preset in the stress compensation layer 400, during the cooling process after annealing, the initial internal stress can offset the residual internal stress of the silicon substrate 100 and the lithium niobate thin film layer 310, thereby reducing or even eliminating the residual internal stress of the lithium niobate thin film-silicon substrate composite structure. This can improve the warping of the lithium niobate thin film-silicon substrate composite structure and the lattice distortion of lithium niobate, thereby improving the yield of the lithium niobate thin film-silicon substrate composite structure.

[0108] In some embodiments of this application, see Figure 5 As shown, after providing a silicon substrate 100 and a lithium niobate wafer 300, and forming a separation layer 320 in the lithium niobate wafer 300 by ion implantation, and forming a lithium niobate thin film layer 310 and a lithium niobate residual layer 330 on both sides of the separation layer 320 respectively, a stress compensation layer 400 is formed, specifically including: forming a stress compensation layer 400 on one side of the silicon substrate 100.

[0109] For example, a stress compensation layer 400 is formed on one side of a silicon substrate 100 using processes such as plasma-enhanced chemical vapor deposition (PECVD) or magnetron sputtering. In this process, by precisely controlling the process parameters, it is possible to preset the initial internal stress in the stress compensation layer 400.

[0110] Furthermore, after forming the stress compensation layer 400, a lithium niobate wafer-silicon substrate bonding structure is formed, specifically including bonding the silicon substrate 100 and the lithium niobate wafer 300 in an opposing manner with the stress compensation layer 400 and the lithium niobate thin film layer 310 facing each other.

[0111] It should be noted that the stress compensation layer 400 in this embodiment is located between the silicon substrate 100 and the lithium niobate wafer 300. Specifically, the stress compensation layer 400 is located between the silicon substrate 100 and the lithium niobate thin film layer 310.

[0112] It is worth mentioning that during the annealing process of the lithium niobate wafer-silicon substrate bonding structure of the present application embodiment to remove the lithium niobate residual layer 330, the initial internal stress in the stress compensation layer 400 can partially or even completely offset the residual internal stress in the silicon substrate 100 and the lithium niobate thin film layer 310, thereby reducing or even eliminating the residual internal stress of the lithium niobate thin film-silicon substrate composite structure. This can improve the warping of the lithium niobate thin film-silicon substrate composite structure and improve the lattice distortion of lithium niobate, thereby improving the yield of the lithium niobate thin film-silicon substrate composite structure.

[0113] In some embodiments of this application, see Figure 9As shown, after providing a silicon substrate 100 and a lithium niobate wafer 300, and forming a separation layer 320 in the lithium niobate wafer 300 by ion implantation, such that a lithium niobate thin film layer 310 and a lithium niobate residual layer 330 are formed on both sides of the separation layer 320 respectively, a stress compensation layer 400 is formed. Specifically, it includes forming a first sub-compensation layer 401 on one side of the silicon substrate 100, and forming a second sub-compensation layer 402 on the side of the lithium niobate thin film layer 310 away from the lithium niobate residual layer 330; the first sub-compensation layer 401 and the second sub-compensation layer 402 form the stress compensation layer 400.

[0114] It should be noted that the first sub-compensation layer 401 and the second sub-compensation layer 402 together form the stress compensation layer 400. That is, the stress compensation layer 400 in this embodiment includes multiple sub-compensation layers. This embodiment only illustrates, by way of example, that the stress compensation layer 400 includes two sub-compensation layers. In some cases, an intermediate compensation layer 404 can be formed on the side of the first sub-compensation layer 401 facing away from the silicon substrate 100, and an intermediate compensation layer 404 can be formed on the side of the second sub-compensation layer 402 facing away from the lithium niobate thin film layer 310, so that the final stress compensation layer 400 includes more than two sub-compensation layers. For example, see [link to relevant documentation]. Figure 10 As shown, the stress compensation layer 400 includes a first sub-compensation layer 401, an intermediate compensation layer 404, and a second sub-compensation layer 402 in sequence along the direction from the silicon substrate layer 200 toward the lithium niobate thin film layer 310.

[0115] For example, a first sub-compensation layer 401 is formed on one side of the silicon substrate 100 using processes such as plasma-enhanced chemical vapor deposition (PECVD) or magnetron sputtering, and a second sub-compensation layer 402 is formed on the side of the lithium niobate thin film layer 310 opposite to the lithium niobate residue layer 330 using processes such as plasma-enhanced chemical vapor deposition (PECVD) or magnetron sputtering. During this process, by precisely controlling the process parameters, the internal stress in the first sub-compensation layer 401 and the second sub-compensation layer 402 can be preset. The preset internal stress in the first sub-compensation layer 401 and the preset internal stress in the second sub-compensation layer 402 together form the initial internal stress of the stress compensation layer 400.

[0116] In another example, the preset internal stress in the first sub-compensation layer 401 is less than, equal to or greater than the preset internal stress in the second sub-compensation layer 402.

[0117] As another example, the direction of the preset internal stress in the first sub-compensation layer 401 is the same as or opposite to the direction of the preset internal stress in the second sub-compensation layer 402. It should be noted that when the direction of the internal stress in the first sub-compensation layer 401 is the same as the direction of the internal stress in the second sub-compensation layer 402, the internal stress in both the first sub-compensation layer 401 and the second sub-compensation layer 402 is either tensile stress or compressive stress; when the direction of the internal stress in the first sub-compensation layer 401 is opposite to the direction of the internal stress in the second sub-compensation layer 402, the internal stress in one of the first sub-compensation layer 401 and the second sub-compensation layer 402 is tensile stress, and the internal stress in the other of the first sub-compensation layer 401 and the second sub-compensation layer 402 is compressive stress.

[0118] Furthermore, after forming the stress compensation layer 400, a lithium niobate wafer-silicon substrate bonding structure is formed, specifically including bonding the silicon substrate 100 and the lithium niobate wafer 300 in an opposing manner with the first sub-compensation layer 401 and the second sub-compensation layer 402 facing each other.

[0119] It should be noted that the stress compensation layer 400 in this embodiment is located between the silicon substrate 100 and the lithium niobate wafer 300. Specifically, the stress compensation layer 400 is located between the silicon substrate 100 and the lithium niobate thin film layer 310.

[0120] It is worth mentioning that during the annealing process of the lithium niobate wafer-silicon substrate bonding structure of the present application embodiment to remove the lithium niobate residual layer 330, the initial internal stress in the stress compensation layer 400 can partially or even completely offset the residual internal stress in the silicon substrate 100 and the lithium niobate thin film layer 310, thereby reducing or even eliminating the residual internal stress of the lithium niobate thin film-silicon substrate composite structure. This can improve the warping of the lithium niobate thin film-silicon substrate composite structure and improve the lattice distortion of lithium niobate, thereby improving the yield of the lithium niobate thin film-silicon substrate composite structure.

[0121] In some embodiments of this application, see Figure 11 As shown, after providing a silicon substrate 100 and a lithium niobate wafer 300, and forming a separation layer 320 in the lithium niobate wafer 300 by ion implantation, and forming a lithium niobate thin film layer 310 and a lithium niobate residual layer 330 on both sides of the separation layer 320 respectively, a stress compensation layer 400 is formed. Specifically, it includes forming a first coordination compensation layer 410 on one side of the silicon substrate 100, and forming a second coordination compensation layer 420 on the side of the lithium niobate residual layer 330 away from the lithium niobate thin film layer 310.

[0122] It should be noted that both the first mating compensation layer 410 and the second mating compensation layer 420 are stress compensation layers 400, that is, in this embodiment of the application, the number of stress compensation layers 400 is two.

[0123] For example, a first coordination compensation layer 410 is formed on one side of the silicon substrate 100 using processes such as plasma-enhanced chemical vapor deposition (PECVD) or magnetron sputtering, and a second coordination compensation layer 420 is formed on the side of the lithium niobate residue layer 330 opposite to the lithium niobate thin film layer 310 using processes such as plasma-enhanced chemical vapor deposition (PECVD) or magnetron sputtering. In this process, by precisely controlling the process parameters, it is possible to preset the initial internal stress in both the first coordination compensation layer 410 and the second coordination compensation layer 420.

[0124] In another example, the preset initial internal stress in the first mating compensation layer 410 is less than, equal to or greater than the preset initial internal stress in the second mating compensation layer 420.

[0125] As another example, since both the first matching compensation layer 410 and the second matching compensation layer 420 are stress compensation layers 400, and in some cases, the stress compensation layer 400 may include multiple sub-compensation layers, the internal stress directions of the multiple sub-compensation layers may be the same or opposite, therefore, the direction of the preset initial internal stress in the first matching compensation layer 410 and the direction of the preset initial internal stress in the second matching compensation layer 420 are at least partially the same or at least partially opposite.

[0126] Furthermore, after forming the stress compensation layer 400, a lithium niobate wafer-silicon substrate bonding structure is formed, specifically including bonding the silicon substrate 100 and the lithium niobate wafer 300 in an opposing manner with the first compensation layer 410 and the lithium niobate thin film layer 310 facing each other.

[0127] It should be noted that, in the embodiments of this application, a stress compensation layer 400 is provided between the silicon substrate 100 and the lithium niobate thin film layer 310, and a stress compensation layer 400 is also provided on the side of the lithium niobate residual layer 330 away from the silicon substrate 100.

[0128] It is worth mentioning that during the annealing process of the lithium niobate wafer-silicon substrate bonding structure of this application embodiment to remove the lithium niobate residual layer 330, the initial internal stress in the first coordination compensation layer 410 and the initial internal stress in the second coordination compensation layer 420 can cooperate to partially or completely offset the residual internal stress in the silicon substrate 100 and the lithium niobate thin film layer 310, thereby reducing or even eliminating the residual internal stress of the lithium niobate thin film-silicon substrate composite structure. This can improve the warping of the lithium niobate thin film-silicon substrate composite structure and improve the lattice distortion of lithium niobate, thereby improving the yield of the lithium niobate thin film-silicon substrate composite structure.

[0129] Furthermore, during the process of stripping the lithium niobate residual layer 330, since the second coordination compensation layer 420 is formed on the lithium niobate residual layer 330, the second coordination compensation layer 420 is also stripped from the lithium niobate wafer-silicon substrate bonding structure along with the lithium niobate residual layer 330.

[0130] In some embodiments of this application, see Figure 4 As shown, after providing a silicon substrate 100 and a lithium niobate wafer 300, and forming a separation layer 320 in the lithium niobate wafer 300 by ion implantation, and forming a lithium niobate thin film layer 310 and a lithium niobate residual layer 330 on both sides of the separation layer 320 respectively, a stress compensation layer 400 is formed. Specifically, the stress compensation layer 400 is formed on the side of the lithium niobate thin film layer 310 away from the lithium niobate residual layer 330.

[0131] For example, a stress compensation layer 400 is formed on the side of the lithium niobate thin film layer 310 away from the lithium niobate residue layer 330 using processes such as plasma-enhanced chemical vapor deposition (PECVD) or magnetron sputtering. In this process, by precisely controlling the process parameters, it is possible to preset the initial internal stress in the stress compensation layer 400.

[0132] Furthermore, after forming the stress compensation layer 400, a lithium niobate wafer-silicon substrate bonding structure is formed, specifically including bonding the silicon substrate 100 and the lithium niobate wafer 300 in such a way that the silicon substrate 100 and the stress compensation layer 400 face each other.

[0133] It should be noted that the stress compensation layer 400 in this embodiment is located between the silicon substrate 100 and the lithium niobate wafer 300. Specifically, the stress compensation layer 400 is located between the silicon substrate 100 and the lithium niobate thin film layer 310.

[0134] It is worth mentioning that during the annealing process of the lithium niobate wafer-silicon substrate bonding structure of the present application embodiment to remove the lithium niobate residual layer 330, the initial internal stress in the stress compensation layer 400 can partially or even completely offset the residual internal stress in the silicon substrate 100 and the lithium niobate thin film layer 310, thereby reducing or even eliminating the residual internal stress of the lithium niobate thin film-silicon substrate composite structure. This can improve the warping of the lithium niobate thin film-silicon substrate composite structure and improve the lattice distortion of lithium niobate, thereby improving the yield of the lithium niobate thin film-silicon substrate composite structure.

[0135] In some embodiments of this application, see Figure 12As shown, after providing a silicon substrate 100 and a lithium niobate wafer 300, and forming a separation layer 320 in the lithium niobate wafer 300 by ion implantation, and forming a lithium niobate thin film layer 310 and a lithium niobate residual layer 330 on both sides of the separation layer 320 respectively, a stress compensation layer 400 is formed. Specifically, the stress compensation layer 400 is formed on the side of the lithium niobate residual layer 330 away from the lithium niobate thin film layer 310.

[0136] For example, a stress compensation layer 400 is formed on the side of the lithium niobate residue layer 330 away from the lithium niobate thin film layer 310 using processes such as plasma-enhanced chemical vapor deposition (PECVD) or magnetron sputtering. In this process, by precisely controlling the process parameters, it is possible to preset the initial internal stress in the stress compensation layer 400.

[0137] Furthermore, after forming the stress compensation layer 400, a lithium niobate wafer-silicon substrate bonding structure is formed, specifically including bonding the silicon substrate 100 and the lithium niobate thin film layer 310 in an opposing manner.

[0138] It is worth mentioning that during the annealing process of the lithium niobate wafer-silicon substrate bonding structure of the present application embodiment to remove the lithium niobate residual layer 330, the initial internal stress in the stress compensation layer 400 can partially or even completely offset the residual internal stress in the silicon substrate 100 and the lithium niobate thin film layer 310, thereby reducing or even eliminating the residual internal stress of the lithium niobate thin film-silicon substrate composite structure. This can improve the warping of the lithium niobate thin film-silicon substrate composite structure and improve the lattice distortion of lithium niobate, thereby improving the yield of the lithium niobate thin film-silicon substrate composite structure.

[0139] It should be noted that during the process of peeling off the lithium niobate residual layer 330, since the stress compensation layer 400 of this embodiment is formed on the lithium niobate residual layer 330, the stress compensation layer 400 is also peeled off from the lithium niobate wafer-silicon substrate bonding structure along with the lithium niobate residual layer 330.

[0140] In some embodiments of this application, the stress compensation layer 400 is made of at least one of silicon dioxide, silicon nitride, and metal.

[0141] For example, the stress compensation layer 400 is made of silicon dioxide, silicon nitride, or metal.

[0142] As another example, the stress compensation layer 400 is made of two of silicon dioxide, silicon nitride, and metal.

[0143] As another example, the stress compensation layer 400 is made of silicon dioxide, silicon nitride, and metal.

[0144] When the material of the stress compensation layer 400 includes a metal, for example, the metal may be titanium or tungsten, etc., without particular limitation.

[0145] In some embodiments of this application, the initial internal stress preset in the stress compensation layer 400 includes at least one of tensile stress and compressive stress.

[0146] For example, the initial internal stress of the stress compensation layer 400 is tensile stress or compressive stress.

[0147] Another example is seen in [reference 1]. Figure 6 , Figure 7 and Figure 10 As shown, the stress compensation layer 400 includes multiple sub-compensation layers. The internal stress of some sub-compensation layers is tensile stress, and the internal stress of other sub-compensation layers is compressive stress.

[0148] It is worth mentioning that, see Figure 6 , Figure 7 and Figure 10 As shown, when the stress compensation layer 400 includes multiple sub-compensation layers, and when the stress compensation layer 400 is located between the silicon substrate 100 and the lithium niobate thin film layer 310, since the stress compensation layer 400 directly contacts the silicon substrate 100 and the lithium niobate thin film layer 310 through two independent sub-compensation layers, by designing these two sub-compensation layers differently, internal stresses in different directions can be preset on both sides of the stress compensation layer 400, thereby specifically offsetting the residual internal stresses of the silicon substrate 100 and the lithium niobate thin film layer 310, further improving the warping of the lithium niobate thin film-silicon substrate composite structure, and further improving the lattice distortion of lithium niobate, thereby improving the yield of the lithium niobate thin film-silicon substrate composite structure.

[0149] In some embodiments of this application, the stress compensation layer 400 is a silicon dioxide layer. The silicon dioxide layer can be configured by adjusting deposition parameters, plasma treatment, or setting annealing conditions to create a stress gradient in its thickness direction. This stress gradient refers to a continuous or stepwise change in stress along the thickness direction, thereby providing stress buffering and transition between the silicon substrate layer 200 and the lithium niobate thin film layer 310, reducing stress abrupt changes at the interface and suppressing warping. Exemplarily, the thickness direction of the stress compensation layer 400 is a first direction X.

[0150] In some embodiments of this application, along the bonding direction of the silicon substrate 100 and the lithium niobate wafer 300, exemplarily along the first direction X of this application, where the first direction X is the thickness direction of the silicon substrate 100, the stress compensation layer 400 has a first thickness dimension, wherein the product of the initial internal stress of the stress compensation layer 400 and the first thickness dimension ranges from 5 N / m to 800 N / m.

[0151] For example, the product of the initial internal stress and the first thickness dimension of the stress compensation layer 400 can be 5 N / m, 8 N / m, 10 N / m, 12 N / m, 18 N / m, 20 N / m, 34 N / m, 56 N / m, 78 N / m, 91 N / m, 130 N / m, 150 N / m, 170 N / m, 210 N / m, 240 N / m, 290 N / m, 330 N / m, 360 N / m, 370 N / m, 420 N / m, 460 N / m, 470 N / m, 530 N / m, 590 N / m, 610 N / m, 640 N / m, 680 N / m, 720 N / m, 760 N / m, 790 N / m, or 800 N / m, without any particular limitation.

[0152] In some embodiments of this application, the absolute value of the initial internal stress of the stress compensation layer 400 ranges from 50 MPa to 1.5 GPa.

[0153] For example, the absolute value of the initial internal stress of the stress compensation layer 400 can be 50MPa, 80MPa, 100MPa, 130MPa, 150MPa, 190MPa, 200MPa, 220MPa, 260MPa, 290MPa, 310MPa, 370MPa, 420MPa, 460MPa, 510MPa, 570MPa, 660MPa, 690MPa, 710MPa, 750MPa, 810MPa, 830MPa, 880MPa, 930MPa, 970MPa, 1Gpa, 1.1Gpa, 1.2Gpa, 1.3Gpa, 1.4Gpa, or 1.5Gpa, without any particular limitation.

[0154] Furthermore, the first thickness dimension of the stress compensation layer 400 along the first direction X ranges from 10nm to 1000nm.

[0155] For example, the thickness of the stress compensation layer 400 along the first direction X can be 10nm, 50nm, 80nm, 100nm, 140nm, 170nm, 210nm, 280nm, 320nm, 360nm, 390nm, 440nm, 470nm, 480nm, 500nm, 520nm, 570nm, 590nm, 630nm, 670nm, 740nm, 770nm, 780nm, 810nm, 880nm, 890nm, 910nm, 970nm, 990nm, or 1000nm, without any particular limitation.

[0156] Thirdly, in related technologies, the classical Stoney formula and its simplified model used to analyze thin film stress establish the fundamental relationship between equivalent stress of the thin film, substrate curvature, and material properties, with torque balance as its physical core. However, the classical Stoney formula and its traditional modified forms are usually based on the assumptions of isotropic linear elastic materials and that "the thin film is sufficiently thin relative to the substrate, the substrate bending stiffness is dominant, the system can be approximated as a single-layer thin film, and the film stress is uniform along the plane."

[0157] Regarding the lithium niobate thin film-silicon substrate composite structure involved in the embodiments of this application, on the one hand, multiple sub-compensation layers may be introduced into the stress compensation layer structure. The elastic modulus, thickness and stress state of different sub-compensation layers jointly determine the position of the neutral axis and the bending stiffness of the cross section, so that the bending moment contribution needs to be calculated by superposition according to the stacked structure. On the other hand, silicon and single crystal lithium niobate usually exhibit in-plane anisotropy related to crystal orientation. Their equivalent elastic constants (such as equivalent biaxial modulus and Poisson's ratio) change with the in-plane direction, which may cause the warpage curvature to be inconsistent in different directions.

[0158] For the reasons mentioned above, directly applying the traditional Stoney formula, which is based on isotropy and single-layer approximation, is insufficient to accurately characterize the stress state and warping behavior of this laminated structure.

[0159] Therefore, based on the moment balance principle implied in the Stoney formula, this application extends it to a composite beam / laminate model applicable to multi-layered stacked structures and considering the influence of material anisotropy, for determining the preset initial internal stress of the stress compensation layer.

[0160] Based on the above, this application provides a method for calculating the preset initial internal stress in the stress compensation layer. This method is based on the fundamental physical principle of moment balance implied by the Stoney formula, and extends it to composite beam structures with any number of layers and any thickness ratio.

[0161] In this embodiment, the entire composite structure (silicon substrate layer, lithium niobate thin film layer, stress compensation layer) is considered as a single composite beam, and both residual internal stress and initial internal stress are simplified to forces acting at the midline of each layer. The root cause of warping is the residual internal stress in the lithium niobate thin film layer (…). The net bending moment generated by this composite beam section. The purpose of introducing a stress compensation layer is to reduce its preset initial internal stress ( This generates a compensating bending moment with the opposite direction and a designable magnitude. When these two bending moments reach equilibrium, the net bending moment of the lithium niobate thin film-silicon substrate composite structure is zero, and warping is eliminated.

[0162] The method for calculating the preset initial internal stress in the stress compensation layer of this application embodiment includes:

[0163] During the temperature change ΔT = Tr - Ta < 0, if LN (lithium niobate) and Si are freely deformable, their length changes will differ. However, due to the strong constraint of the bonding interface, their deformation is coordinated, resulting in thermal mismatch strain at the bonding interface, which forms residual strain ε after cooling. res ;

[0164]

[0165] in, and These are the coefficients of thermal expansion of LN and Si, respectively. This residual strain is primarily converted into significant residual tensile stress in the LN thin film. :

[0166]

[0167] in, The Young's modulus of LN is 170 GPa. and These are the coefficients of thermal expansion of LN and Si, respectively. and These are the annealing temperature and room temperature, respectively.

[0168] Exemplary, in the embodiments of this application, , It exhibits a tensile stress of approximately +387 MPa.

[0169] Furthermore, residual tensile stress A net bending moment is generated within the LN film section. Macroscopically, this causes the lithium niobate thin film-silicon substrate composite structure to concave towards the LN surface (defined as negative warping). The core of this application's embodiments is to introduce a pre-set initial internal stress (…). The stress compensation layer generates a reverse compensating bending moment ( ). To balance it, that is:

[0170]

[0171]

[0172] in, and These are the preset internal stress and thickness of the stress compensation layer, respectively. The thickness of the LN film is... and The lever arms are the residual tensile stresses of the stress compensation layer and the LN film, respectively. and The calculation needs to be based on the position of the neutral axis of the composite beam. Taking the stress compensation layer located on the side of the LN film away from Si as an example, the calculation formula is as follows:

[0173] With the bottom of the silicon substrate as the origin (y=0), the neutral axis is the distance from the origin. Determined by the static moment balance of each layer:

[0174]

[0175] The lever arm of each layer of force relative to the neutral axis:

[0176] The combined lever arm of the silicon substrate: ;

[0177] LN layer resultant force arm: ;

[0178] The resultant force arm of the compensation layer: ;

[0179] in: , , These represent the thicknesses of the silicon substrate, LN thin film, and stress compensation layer, respectively.

[0180] Residual thermal stress (tensile stress, positive value) in LN thin film.

[0181] The initial internal stress of the stress compensation layer on the side of the LN thin film away from Si (tensile stress is positive, compressive stress is negative).

[0182] , , Young's modulus of each layer.

[0183] Neutral axis position: This is the axial position of the entire cross section when it is bent without elongation or shortening, and it needs to be calculated first.

[0184] In this embodiment, a negative warp value indicates a concavity in the LN surface, and the residual internal stress effect that causes the concavity in the LN surface is defined as generating a negative bending moment ( <0). To correct the depression, the stress compensation layer needs to generate a positive bending moment ( >0). Analysis shows that a compressive stress layer needs to be used on the silicon substrate ( (Negative), a tensile stress layer needs to be applied to the surface of the LN thin film on the side away from Si. (Positive).

[0185] For example, ;

[0186] , , And assume , The initial target value is set at 500 nm (using 500 nm as an example, the influence of the stress compensation layer's thickness on the neutral axis position can be approximately ignored). The neutral axis and lever arm can be calculated as follows: , , ;

[0187]

[0188] In other words, the design target for the stress-thickness product of the stress compensation layer needs to reach approximately 66 N / m. When the stress compensation layer is located on the surface of the lithium niobate film away from the silicon substrate, it needs to be achieved through a tensile stress layer ( A positive sign indicates a downward pulling effect. A negative sign indicates the opposite direction of the bending moment.

[0189] It should be noted that, in specific designs, the parameters of the stress compensation layer can be determined using the torque balance principle. For typical thickness ratios, to counteract the dominant influence of residual internal stress in the lithium niobate film, the stress compensation layer needs to provide a stress-thickness product of approximately 60% to 100% of the residual stress-thickness product of the lithium niobate film (for stress compensation layers located between the silicon substrate and the lithium niobate film), or 60% to 70% (for stress compensation layers located on the side of the lithium niobate film facing away from the silicon substrate). The specific ratio can be determined through experimental calibration.

[0190] Example 1

[0191] See Figure 8 and Figure 5 As shown, the method for fabricating the semiconductor structure in this application includes:

[0192] A 4-inch silicon substrate 100 with a thickness of 525 μm is provided, and the silicon substrate 100 is cleaned using an RCA cleaning process. A lithium niobate wafer 300 with a thickness of 250 μm is provided, and the lithium niobate wafer 300 is implanted using ion implantation. Ions are implanted to form a separation layer 320 in the lithium niobate wafer 300, with a lithium niobate thin film layer 310 and a lithium niobate residual layer 330 formed on both sides of the separation layer 320, respectively. The ion implantation energy is 100 keV, and the ion implantation dose is... .

[0193] A 300 nm thick silicon dioxide layer is deposited on one side of a silicon substrate 100 using plasma-enhanced chemical vapor deposition (PECVD). This silicon dioxide layer serves as a stress compensation layer 400. By precisely controlling the process parameters, the initial internal stress in the stress compensation layer 400 is preset to be compressive stress, with a compressive stress of 220 MPa. Exemplarily, during the formation of the silicon dioxide layer, the following parameters are selected... and The gas ratio is 1:2, the chamber pressure is 300 mTorr, and the radio frequency power is 300 W.

[0194] The lithium niobate thin film layer 310 is hydrophilically bonded to the stress compensation layer 400 on the silicon substrate 100 at room temperature to form a lithium niobate wafer-silicon substrate bonding structure.

[0195] The lithium niobate wafer-silicon substrate bonding structure was placed in an annealing furnace and heated to 200°C at a rate of 3°C / min, then held at that temperature for 2 hours, and finally slowly cooled to room temperature at a rate of 1°C / min. During this process, the lithium niobate residue layer 330 was peeled off to form a lithium niobate thin film-silicon substrate composite structure.

[0196] The lithium niobate thin film layer 310 was thinned to 400 nm by mechanical exfoliation and chemical mechanical polishing.

[0197] Example 2

[0198] See Figure 8 and Figure 13 As shown, the method for fabricating the semiconductor structure in this application includes:

[0199] A 4-inch silicon substrate 100 with a thickness of 525 μm is provided, and the silicon substrate 100 is cleaned using an RCA cleaning process. A lithium niobate wafer 300 with a thickness of 250 μm is provided, and the lithium niobate wafer 300 is implanted using ion implantation. Ions are implanted to form a separation layer 320 in the lithium niobate wafer 300, with a lithium niobate thin film layer 310 and a lithium niobate residual layer 330 formed on both sides of the separation layer 320, respectively. The ion implantation energy is 100 keV, and the ion implantation dose is... .

[0200] A 100 nm thick Si3N4 layer was deposited on one side of a silicon substrate 100 using plasma-enhanced chemical vapor deposition (PECVD). Within the same chamber, the process gas was switched between different gases. and The flow ratio is approximately 1:3. By increasing the RF power (e.g., 400W) and adjusting the pressure, the preset internal stress in the Si3N4 layer is tensile stress, and the tensile stress is 250MPa.

[0201] A 325 nm thick silicon dioxide layer was deposited on the side of the Si3N4 layer facing away from the silicon substrate 100 using plasma-enhanced chemical vapor deposition (PECVD). By precisely controlling the process parameters, the pre-set internal stress in the silicon dioxide layer was made compressive, with a compressive stress of 280 MPa. Exemplarily, during the formation of the silicon dioxide layer, the following parameters were selected: and The gas ratio is 1:2, the chamber pressure is 300 mTorr, and the radio frequency power is 300 W.

[0202] In this embodiment, the Si3N4 layer and the silicon dioxide layer together form the stress compensation layer 400.

[0203] The lithium niobate thin film layer 310 is hydrophilically bonded to the stress compensation layer 400 on the silicon substrate 100 at room temperature to form a lithium niobate wafer-silicon substrate bonding structure.

[0204] The lithium niobate wafer-silicon substrate bonding structure was placed in an annealing furnace and heated to 200°C at a rate of 3°C / min, then held at that temperature for 2 hours, and finally slowly cooled to room temperature at a rate of 1°C / min. During this process, the lithium niobate residue layer 330 was peeled off to form a lithium niobate thin film-silicon substrate composite structure.

[0205] The lithium niobate thin film layer 310 was thinned to 400 nm by mechanical exfoliation and chemical mechanical polishing.

[0206] Example 3

[0207] See Figure 8 and Figure 5 As shown, the method for fabricating the semiconductor structure in this application includes:

[0208] A 4-inch silicon substrate 100 with a thickness of 525 μm is provided, and the silicon substrate 100 is cleaned using an RCA cleaning process. A lithium niobate wafer 300 with a thickness of 250 μm is provided, and the lithium niobate wafer 300 is implanted using ion implantation. Ions are implanted to form a separation layer 320 in the lithium niobate wafer 300, with a lithium niobate thin film layer 310 and a lithium niobate residual layer 330 formed on both sides of the separation layer 320, respectively. The ion implantation energy is 100 keV, and the ion implantation dose is... .

[0209] A 100 nm thick titanium layer was deposited on a silicon substrate 100 using a DC magnetron sputtering process. This titanium layer served as a stress compensation layer 400. By controlling the working gas pressure to 0.3 Pa and the sputtering power to 500 W, the initial internal stress in the stress compensation layer 400 was preset to be a compressive stress of 660 MPa.

[0210] The lithium niobate thin film layer 310 is hydrophilically bonded to the stress compensation layer 400 on the silicon substrate 100 at room temperature to form a lithium niobate wafer-silicon substrate bonding structure.

[0211] The lithium niobate wafer-silicon substrate bonding structure was placed in an annealing furnace and heated to 200°C at a rate of 3°C / min, then held at that temperature for 2 hours, and finally slowly cooled to room temperature at a rate of 1°C / min. During this process, the lithium niobate residue layer 330 was peeled off to form a lithium niobate thin film-silicon substrate composite structure.

[0212] The lithium niobate thin film layer 310 was thinned to 400 nm by mechanical exfoliation and chemical mechanical polishing.

[0213] Example 4

[0214] See Figure 8 and Figure 12 As shown, the method for fabricating the semiconductor structure in this application includes:

[0215] A 4-inch silicon substrate 100 with a thickness of 525 μm is provided, and the silicon substrate 100 is cleaned using an RCA cleaning process. A lithium niobate wafer 300 with a thickness of 250 μm is provided, and the lithium niobate wafer 300 is implanted using ion implantation. Ions are implanted to form a separation layer 320 in the lithium niobate wafer 300, with a lithium niobate thin film layer 310 and a lithium niobate residual layer 330 formed on both sides of the separation layer 320, respectively. The ion implantation energy is 100 keV, and the ion implantation dose is... .

[0216] It should be noted that in this embodiment, only the silicon substrate 100 is cleaned and plasma activated to prepare the silicon substrate 100 for bonding.

[0217] A 200 nm thick Si3N4 layer was deposited on the side of the lithium niobate residue layer 330 opposite to the lithium niobate thin film layer 310 using plasma-enhanced chemical vapor deposition (PECVD). The Si3N4 layer served as a stress compensation layer 400. In the same chamber, the process gas was switched to... and The flow ratio is approximately 1:3. By increasing the RF power (e.g., 400W) and adjusting the pressure, the preset internal stress in the Si3N4 layer is tensile stress, and the tensile stress is 330MPa.

[0218] The lithium niobate thin film layer 310 is hydrophilically bonded to the silicon substrate 100 at room temperature to form a lithium niobate wafer-silicon substrate bonding structure.

[0219] The lithium niobate wafer-silicon substrate bonding structure was placed in an annealing furnace and heated to 200°C at a rate of 3°C / min, then held at that temperature for 2 hours, and finally slowly cooled to room temperature at a rate of 1°C / min. During this process, the lithium niobate residue layer 330 was peeled off to form a lithium niobate thin film-silicon substrate composite structure. Since the stress compensation layer 400 was formed on the lithium niobate residue layer 330, the stress compensation layer 400 was also peeled off from the lithium niobate wafer-silicon substrate bonding structure along with the lithium niobate residue layer 330.

[0220] The lithium niobate thin film layer 310 was thinned to 400 nm by mechanical exfoliation and chemical mechanical polishing.

[0221] Example 5

[0222] See Figure 8 and Figure 14 As shown, the method for fabricating the semiconductor structure in this application includes:

[0223] A 4-inch silicon substrate 100 with a thickness of 525 μm is provided, and the silicon substrate 100 is cleaned using an RCA cleaning process. A lithium niobate wafer 300 with a thickness of 250 μm is provided, and the lithium niobate wafer 300 is implanted using ion implantation. Ions are implanted to form a separation layer 320 in the lithium niobate wafer 300, with a lithium niobate thin film layer 310 and a lithium niobate residual layer 330 formed on both sides of the separation layer 320, respectively. The ion implantation energy is 100 keV, and the ion implantation dose is... .

[0224] It should be noted that in this embodiment, only the silicon substrate 100 is cleaned and plasma activated to prepare the silicon substrate 100 for bonding.

[0225] A 100 nm thick silicon dioxide layer was deposited on the side of the lithium niobate residue layer 330 opposite to the lithium niobate thin film layer 310 using plasma-enhanced chemical vapor deposition (PECVD). By precisely controlling the process parameters, the preset internal stress in the silicon dioxide layer was made compressive stress, specifically 110 MPa. Exemplarily, during the formation of the silicon dioxide layer, the following process was selected... and The gas ratio is 1:2, the chamber pressure is 300 mTorr, and the radio frequency power is 300 W.

[0226] A 200 nm thick Si3N4 layer was deposited on the side of the silicon dioxide layer away from the lithium niobate residue layer 330 using plasma-enhanced chemical vapor deposition (PECVD). Within the same chamber, the process gas was switched to... and The flow ratio is approximately 1:3. By increasing the RF power (e.g., 400W) and adjusting the pressure, the preset internal stress in the Si3N4 layer is tensile stress, and the tensile stress is 385MPa.

[0227] In this embodiment, the Si3N4 layer and the silicon dioxide layer together form the stress compensation layer 400.

[0228] The lithium niobate thin film layer 310 is hydrophilically bonded to the silicon substrate 100 at room temperature to form a lithium niobate wafer-silicon substrate bonding structure.

[0229] The lithium niobate wafer-silicon substrate bonding structure was placed in an annealing furnace and heated to 200°C at a rate of 3°C / min, then held at that temperature for 2 hours, and finally slowly cooled to room temperature at a rate of 1°C / min. During this process, the lithium niobate residue layer 330 was peeled off to form a lithium niobate thin film-silicon substrate composite structure. Since the stress compensation layer 400 was formed on the lithium niobate residue layer 330, the stress compensation layer 400 was also peeled off from the lithium niobate wafer-silicon substrate bonding structure along with the lithium niobate residue layer 330.

[0230] The lithium niobate thin film layer 310 was thinned to 400 nm by mechanical exfoliation and chemical mechanical polishing.

[0231] Example 6

[0232] See Figure 8 and Figure 12 As shown, the method for fabricating the semiconductor structure in this application includes:

[0233] A 4-inch silicon substrate 100 with a thickness of 525 μm is provided, and the silicon substrate 100 is cleaned using an RCA cleaning process. A lithium niobate wafer 300 with a thickness of 250 μm is provided, and the lithium niobate wafer 300 is implanted using ion implantation. Ions are implanted to form a separation layer 320 in the lithium niobate wafer 300, with a lithium niobate thin film layer 310 and a lithium niobate residual layer 330 formed on both sides of the separation layer 320, respectively. The ion implantation energy is 100 keV, and the ion implantation dose is... .

[0234] It should be noted that in this embodiment, only the silicon substrate 100 is cleaned and plasma activated to prepare the silicon substrate 100 for bonding.

[0235] A 100 nm thick titanium layer was deposited on the side of the lithium niobate residue layer 330 opposite to the lithium niobate thin film layer 310 using a DC magnetron sputtering process. The titanium layer served as the stress compensation layer 400. By controlling the working gas pressure to 1.5 Pa and the sputtering power to 150 W, the initial internal stress in the stress compensation layer 400 was preset to be tensile stress, and the tensile stress was 660 MPa.

[0236] The lithium niobate thin film layer 310 is hydrophilically bonded to the silicon substrate 100 at room temperature to form a lithium niobate wafer-silicon substrate bonding structure.

[0237] The lithium niobate wafer-silicon substrate bonding structure was placed in an annealing furnace and heated to 200°C at a rate of 3°C / min, then held at that temperature for 2 hours, and finally slowly cooled to room temperature at a rate of 1°C / min. During this process, the lithium niobate residue layer 330 was peeled off to form a lithium niobate thin film-silicon substrate composite structure. Since the stress compensation layer 400 was formed on the lithium niobate residue layer 330, the stress compensation layer 400 was also peeled off from the lithium niobate wafer-silicon substrate bonding structure along with the lithium niobate residue layer 330.

[0238] The lithium niobate thin film layer 310 was thinned to 400 nm by mechanical exfoliation and chemical mechanical polishing.

[0239] Comparative Example 1

[0240] See Figure 2 As shown, a 4-inch silicon substrate 100 with a thickness of 525 μm is provided, and the silicon substrate 100 is cleaned using an RCA cleaning process. A lithium niobate wafer 300 with a thickness of 250 μm is provided, and the lithium niobate wafer 300 is implanted by ion implantation. Ions are implanted to form a separation layer 320 in the lithium niobate wafer 300, with a lithium niobate thin film layer 310 and a lithium niobate residual layer 330 formed on both sides of the separation layer 320, respectively. The ion implantation energy is 100 keV, and the ion implantation dose is... .

[0241] It should be noted that in this embodiment, only the silicon substrate 100 is cleaned and plasma activated to prepare the silicon substrate 100 for bonding.

[0242] The lithium niobate thin film layer 310 is hydrophilically bonded to the silicon substrate 100 at room temperature to form a lithium niobate wafer-silicon substrate bonding structure.

[0243] The lithium niobate wafer-silicon substrate bonding structure was placed in an annealing furnace and heated to 200°C at a rate of 1°C / min, then held at that temperature for 2 hours, and finally slowly cooled to room temperature at a rate of 0.5°C / min. During this process, the lithium niobate residue layer 330 was peeled off to form a lithium niobate thin film-silicon substrate composite structure.

[0244] The lithium niobate thin film layer 310 was thinned to 400 nm by mechanical exfoliation and chemical mechanical polishing.

[0245] Comparative Example 2

[0246] A 4-inch silicon substrate 100 with a thickness of 525 μm is provided, and the silicon substrate 100 is cleaned using an RCA cleaning process. A lithium niobate wafer 300 with a thickness of 250 μm is provided, and the lithium niobate wafer 300 is implanted using ion implantation. Ions are implanted to form a separation layer 320 in the lithium niobate wafer 300, with a lithium niobate thin film layer 310 and a lithium niobate residual layer 330 formed on both sides of the separation layer 320, respectively. The ion implantation energy is 100 keV, and the ion implantation dose is... .

[0247] A 500 nm thick silicon dioxide layer was deposited on a silicon substrate 100 using a conventional plasma-enhanced chemical vapor deposition (PECVD) process.

[0248] The lithium niobate thin film layer 310 is hydrophilically bonded to the silicon dioxide layer on the silicon substrate 100 at room temperature to form a lithium niobate wafer-silicon substrate bonding structure.

[0249] The lithium niobate wafer-silicon substrate bonding structure was placed in an annealing furnace and heated to 200°C at a rate of 1°C / min, then held at that temperature for 2 hours, and finally slowly cooled to room temperature at a rate of 0.5°C / min. During this process, the lithium niobate residue layer 330 was peeled off to form a lithium niobate thin film-silicon substrate composite structure.

[0250] The lithium niobate thin film layer 310 was thinned to 400 nm by mechanical exfoliation and chemical mechanical polishing.

[0251] The lithium niobate thin film-silicon substrate composite structures obtained in Examples 1 to 6 were measured using a surface profilometer to obtain the corresponding bending radius (BOW) values ​​of the lithium niobate thin film-silicon substrate composite structures. (See [reference needed]). Figure 15As shown in Table 1, the residual internal stress of the lithium niobate thin film-silicon substrate composite structure calculated based on the bending radius (BOW) value is as follows.

[0252] Table 1

[0253]

[0254] from Figure 15 As can be seen from Table 1, by setting a stress compensation layer 400 and pre-setting an initial internal stress in the stress compensation layer 400, the initial internal stress can offset the residual internal stress of the silicon substrate 100 and the lithium niobate thin film layer 310 during the cooling process after annealing. This achieves the effect of reducing or even eliminating the residual internal stress of the lithium niobate thin film-silicon substrate composite structure, thereby improving the warping of the lithium niobate thin film-silicon substrate composite structure and the lattice distortion of lithium niobate, thus improving the yield of the lithium niobate thin film-silicon substrate composite structure.

[0255] 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 semiconductor structure, characterized in that: include, Silicon substrate; A lithium niobate thin film layer, wherein the lithium niobate thin film layer is formed along a first direction on one side of the silicon substrate layer; A stress compensation layer is formed along the first direction between the silicon substrate layer and the lithium niobate thin film layer, the stress compensation layer being used to partially or completely offset the residual internal stress of the silicon substrate layer and the lithium niobate thin film layer.

2. The semiconductor structure according to claim 1, characterized in that: The stress compensation layer is made of at least one of silicon dioxide, silicon nitride, and metal.

3. The semiconductor structure according to claim 1, characterized in that: The stress compensation layer comprises a plurality of sequentially stacked sub-compensation layers along the first direction, and each sub-compensation layer is made of at least one of silicon dioxide, silicon nitride, and metal.

4. The semiconductor structure according to claim 1, characterized in that: The sum of the residual internal stress of the silicon substrate layer and the residual internal stress of the lithium niobate thin film layer is no greater than 50 MPa.

5. The semiconductor structure according to any one of claims 1-3, characterized in that: The thickness of the silicon substrate layer along the first direction ranges from 100 μm to 1000 μm; And / or, the thickness of the lithium niobate thin film layer along the first direction ranges from 100 nm to 1000 nm; And / or, the thickness of the stress compensation layer along the first direction ranges from 10 nm to 1000 nm.

6. A method for fabricating a semiconductor structure, characterized in that: include, A silicon substrate and a lithium niobate wafer are provided. A separation layer is formed in the lithium niobate wafer by ion implantation. A lithium niobate thin film layer and a lithium niobate residual layer are formed on both sides of the separation layer, respectively. A stress compensation layer is formed on the silicon substrate, and / or the stress compensation layer is formed on the lithium niobate wafer; The stress compensation layer has initial internal stress; A lithium niobate wafer-silicon substrate bonding structure is formed, wherein the stress compensation layer is located between the silicon substrate and the lithium niobate wafer, or the stress compensation layer is located on the side of the lithium niobate wafer facing away from the silicon substrate; The residual lithium niobate layer is removed by annealing.

7. The preparation method according to claim 6, characterized in that: The formation of the stress compensation layer specifically includes forming the stress compensation layer on one side of the silicon substrate; The formation of the lithium niobate wafer-silicon substrate bonding structure specifically includes, The silicon substrate and the lithium niobate wafer are bonded together with the stress compensation layer and the lithium niobate thin film layer facing each other.

8. The preparation method according to claim 6, characterized in that: The formation of the stress compensation layer specifically includes forming a first sub-compensation layer on one side of the silicon substrate and forming a second sub-compensation layer on the side of the lithium niobate thin film layer opposite to the lithium niobate residual layer; the first sub-compensation layer and the second sub-compensation layer form the stress compensation layer; The formation of the lithium niobate wafer-silicon substrate bonding structure specifically includes, The silicon substrate and the lithium niobate wafer are bonded together with the first sub-compensation layer and the second sub-compensation layer facing each other.

9. The preparation method according to claim 6, characterized in that: The formation of the stress compensation layer specifically includes forming a first coordination compensation layer on one side of the silicon substrate and forming a second coordination compensation layer on the side of the lithium niobate residue layer away from the lithium niobate thin film layer; the first coordination compensation layer and the second coordination compensation layer respectively serve as the stress compensation layer. The formation of the lithium niobate wafer-silicon substrate bonding structure specifically includes, The silicon substrate and the lithium niobate wafer are bonded together with the first compensation layer and the lithium niobate thin film layer facing each other.

10. The preparation method according to claim 6, characterized in that: The formation of the stress compensation layer specifically includes forming the stress compensation layer on the side of the lithium niobate thin film layer away from the lithium niobate residual layer. The formation of the lithium niobate wafer-silicon substrate bonding structure specifically includes, The silicon substrate and the lithium niobate wafer are bonded together with the silicon substrate and the stress compensation layer facing each other.

11. The preparation method according to claim 6, characterized in that: The formation of the stress compensation layer specifically includes forming the stress compensation layer on the side of the lithium niobate residual layer that is opposite to the lithium niobate thin film layer. The formation of the lithium niobate wafer-silicon substrate bonding structure specifically includes, The silicon substrate and the lithium niobate wafer are bonded together with the silicon substrate and the lithium niobate thin film layer facing each other.

12. The preparation method according to any one of claims 6-11, characterized in that: The stress compensation layer is made of at least one of silicon dioxide, silicon nitride, and metal.

13. The preparation method according to any one of claims 6-11, characterized in that: The initial internal stress includes at least one of compressive stress and tensile stress.

14. The preparation method according to any one of claims 6-11, characterized in that: Along the bonding direction between the silicon substrate and the lithium niobate wafer, the stress compensation layer has a first thickness dimension; the product of the initial internal stress and the first thickness dimension ranges from 5 N / m to 800 N / m.

15. The preparation method according to claim 14, characterized in that: The absolute value range of the initial internal stress is 50 MPa-1.5 GPa; And / or, the first thickness dimension ranges from 10nm to 1000nm.

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