A composite structure of a surface acoustic wave device substrate and a manufacturing method thereof

Abstract

The application provides a composite structure of a surface acoustic wave device substrate and a preparation method thereof. The composite structure comprises, from bottom to top, a single crystal silicon substrate layer, a polycrystalline silicon layer, an absorbing layer, an insulating layer and a piezoelectric single crystal thin film layer. The absorbing layer is used for absorbing incident light during photolithography. The application can effectively absorb the light during photolithography, weaken scattering and reflection during photolithography, improve the resolution of photolithography, inhibit the surface parasitic conductance effect, improve the performance of the prepared device and the working stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of acoustic wave surface device, and particularly relates to a composite structure of an acoustic surface wave device substrate and a preparation method. BACKGROUND

[0002] The acoustic surface wave device is widely applied to the preparation of a radio frequency filter. The piezoelectric substrate required by the acoustic surface wave device is usually selected as a high-resistance silicon material as a support substrate. However, with the increase of the frequency, a conductive layer is induced at the interface between the high-resistance silicon and the upper insulating layer, which leads to the decrease of the effective resistivity of the substrate. By preparing a polycrystalline silicon layer, the movement of the carriers at the interface is limited by the carrier traps in the polycrystalline silicon layer, which can effectively prevent the decrease of the resistivity of the substrate in the radio frequency application. By preparing a thin layer with a greater carrier trap density in the polycrystalline silicon, more sufficient carrier traps can be provided.

[0003] However, the grown polycrystalline silicon usually has a relatively rough surface, which is easy to affect the subsequent photolithography process. The scattering and reflection of the light of the photolithography through the rough surface will lead to the blur of the exposure pattern, cause the proximity effect, and finally lead to the decrease of the photolithography resolution and further lead to the decrease of the performance of the prepared device. SUMMARY

[0004] The present application provides a composite structure of an acoustic surface wave device substrate and a preparation method, and aims to solve the technical problem of how to weaken the photolithography scattering and reflection of the surface of the acoustic surface wave device substrate.

[0005] To solve the above technical problem, the technical scheme adopted by the present application is as follows: a composite structure of an acoustic surface wave device substrate, the composite structure comprises, from bottom to top, a single crystal silicon substrate layer, a polycrystalline silicon layer, an absorbing layer, an insulating layer and a piezoelectric single crystal thin film layer, and the absorbing layer is used to absorb the incident light in the photolithography.

[0006] Further, the absorbing layer is selected from porous silicon or amorphous silicon.

[0007] Further, when the absorbing layer is an amorphous silicon layer, a plurality of grooves or protrusions are arranged on the absorbing layer, and the plurality of grooves or protrusions are distributed at equal intervals.

[0008] Further, the thickness of the absorbing layer is not less than 100 nm, when the absorbing layer is selected from amorphous silicon, the interval between the plurality of grooves or protrusions prepared on the absorbing layer is not less than 1 um, and the depth-width ratio of the grooves is greater than 1.

[0009] Preferably, when the absorbing layer is selected from polycrystalline silicon, the pore size of the polycrystalline silicon is less than 50 nm.

[0010] Preferably, the structure of the plurality of grooves or protrusions includes, but is not limited to, a V-shaped structure, an inverted pyramid structure, a conical peak structure, or a stripe structure.

[0011] Further, a trap-rich layer is arranged at the junction of the single-crystal silicon substrate layer and the polycrystalline silicon layer, and the thickness of the trap-rich layer is 50-200 nm.

[0012] Further, the insulating layer is made of one of amorphous aluminum nitride, silicon oxide, and silicon nitride, the piezoelectric single-crystal thin film layer is made of any one of lithium niobate and lithium tantalate, the single-crystal silicon substrate layer is a high-resistance silicon substrate, and the resistance of the high-resistance silicon substrate is greater than 300 Ω·cm.

[0013] Further, the method comprises:

[0014] A single-crystal silicon substrate layer is prepared, and a polycrystalline silicon layer is deposited on the single-crystal silicon substrate layer.

[0015] An absorbing layer is prepared on the polycrystalline silicon layer, and the upper surface of the absorbing layer is selectively etched.

[0016] An insulating layer is prepared on the absorbing layer.

[0017] A piezoelectric single-crystal thin film layer is prepared, and the piezoelectric single-crystal thin film layer is transferred to the insulating layer.

[0018] Preferably, the single-crystal silicon substrate layer is cleaned to obtain a smooth surface.

[0019] Further, the deposition of the polycrystalline silicon layer on the single-crystal silicon substrate layer comprises:

[0020] The polycrystalline silicon layer with a thickness of about 1200 nm is generated on the single-crystal silicon substrate layer by low-pressure chemical vapor deposition in a silane gas atmosphere at a temperature of 600-680 ℃ and a pressure of 0.3 Torr.

[0021] Further, the method further comprises:

[0022] The trap-rich layer is prepared by ion implantation or by introducing carbon-containing or nitrogen-containing gas at the junction of the polycrystalline silicon layer and the single-crystal silicon substrate layer.

[0023] Preferably, the ions implanted in the preparation of the trap-rich layer are hydrogen ions or helium ions.

[0024] Further, the transfer method comprises any one of ion implantation and bond peeling, bonding and grinding thinning.

[0025] Preferably, the transfer method uses the ion implantation and bond peeling method.

[0026] Further, the transferred mode is ion implantation and bonding peeling, the ion implanted into the piezoelectric monocrystal thin film layer is hydrogen or helium ion, the energy range of the ion is 10kev-2000kev, the dose of the ion is 1e15-1e17, and the annealing temperature is 150-350℃.

[0027] By adopting the technical scheme, the application has the following beneficial effects:

[0028] The application provides a composite structure of a surface acoustic wave device substrate and a preparation method thereof. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0030] Figure 1 It is a whole schematic view of the composite structure of the surface acoustic wave device substrate in the embodiment of the application.

[0031] Figure 2 It is a flowchart of the preparation method of the composite structure of the surface acoustic wave device substrate provided in the embodiment of the application.

[0032] Figure 3 It is a flowchart of another preparation method of the composite structure of the surface acoustic wave device substrate provided in the embodiment of the application.

[0033] Figure 4 It is a flowchart of another preparation method of the composite structure of the surface acoustic wave device substrate provided in the embodiment of the application.

[0034] Figure 5 It is a flowchart of another preparation method of the composite structure of the surface acoustic wave device substrate provided in the embodiment of the application.

[0035] The following is a supplementary description of the drawings:

[0036] 1-monocrystal silicon substrate layer; 2-polysilicon layer; 3-trap-rich layer; 4-absorption layer; 5-insulating layer; 6-piezoelectric monocrystal thin film layer. DETAILED DESCRIPTION

[0037] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0038] The term "one embodiment" or "an embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one implementation of the application. The appearances of the term "an embodiment" or "one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily referring to a single embodiment. In the description of embodiments of the present application, it should be understood that the terms "upper", "lower", "top", "bottom", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features. Moreover, the terms "first", "second", etc. are used to distinguish similar objects, and do not necessarily describe a particular order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the application described herein can be implemented in an order other than that illustrated or described herein.

[0039] Embodiment 1:

[0040] Referring to Figures 1-2 The present application provides a composite structure of a surface acoustic wave device substrate and a preparation method thereof. The composite structure comprises, from bottom to top, a single crystal silicon substrate layer 1, a polycrystalline silicon layer 2, an absorption layer 4, an insulating layer 5 and a piezoelectric single crystal thin film layer 6.

[0041] For example, the single crystal silicon substrate layer 1 is a high resistance silicon substrate, the absorption layer 4 is porous silicon, the insulating layer 5 is amorphous aluminum nitride, and the piezoelectric single crystal thin film layer 6 is lithium niobate.

[0042] The absorption layer 4 is used to absorb incident light during lithography. By the absorption layer 4, the lithography light in the ultraviolet band can be effectively absorbed before reaching the surface of the polycrystalline silicon layer 2, the scattering and reflection during lithography can be reduced, the resolution of lithography can be improved, the surface parasitic conductance effect can be suppressed, and the performance and working stability of the prepared device can be improved.

[0043] The preparation method of the composite structure in this embodiment comprises:

[0044] S1, preparing a single crystal silicon substrate layer 1.

[0045] In an example, the single crystal silicon substrate layer 1 is a high resistance silicon substrate, and the high resistance silicon substrate has a resistance greater than 300 Ω·cm.

[0046] S2, cleaning the single crystal silicon substrate layer 1 to obtain a smooth surface, and forming a polycrystalline silicon layer 2 on the single crystal silicon substrate layer 1 by low pressure chemical vapor deposition in a silane gas atmosphere at a temperature of 600-680°C and a pressure of 0.3 Torr, and the polycrystalline silicon layer 2 has a thickness of about 1200 nm.

[0047] The polycrystalline silicon layer 2 is used to provide carrier traps and suppress the parasitic surface conductance effect.

[0048] In an example, the composite structure of the surface acoustic wave device substrate further includes a trap-rich layer 3 disposed at the junction of the single crystal silicon substrate layer 1 and the polycrystalline silicon layer 2, and the trap-rich layer 3 has a thickness of 50-200 nm. The trap-rich layer 3 can prevent the polycrystalline silicon layer 2 from providing insufficient trap density, and the trap-rich layer 3 can provide greater defect density than the polycrystalline silicon layer 2, thereby enhancing the trapping of free carriers and improving the resistivity of the surface acoustic wave device substrate.

[0049] Based on this, after step S2, the method for preparing the composite structure further includes: preparing a trap-rich layer 3 having a thickness of 50-200 nm at the junction of the polycrystalline silicon layer 2 and the single crystal silicon substrate layer 1 by hydrogen ion implantation on the polycrystalline silicon layer 2.

[0050] S3, preparing an absorption layer 4 on the polycrystalline silicon layer 2.

[0051] The absorption layer 4 can be porous silicon, which can improve the light absorption rate of the lithography light due to its own light trapping effect, and the pore size of the polycrystalline silicon is less than 50 nm.

[0052] S4, preparing an insulating layer 5 on the absorption layer 4.

[0053] The insulating layer 5 can provide temperature compensation and a smooth bonding interface.

[0054] In an example, the insulating layer 5 can be amorphous aluminum nitride.

[0055] S5, preparing a piezoelectric single crystal thin film layer 6, and transferring the piezoelectric single crystal thin film layer 6 to the insulating layer 5.

[0056] In an example, the insulating layer 5 can be subjected to CMP processing to obtain a smooth surface before the transfer, and then the prepared piezoelectric single crystal thin film layer 6 is transferred to the insulating layer 5.

[0057] The piezoelectric single crystal thin film layer 6 can be lithium niobate, and the piezoelectric single crystal thin film layer 6 is subjected to hydrogen ion implantation, the energy range of the implanted hydrogen ions is 10 kev-2000 kev, the dose of the implanted hydrogen ions is 1e15-1e17, and the annealing temperature is 150-350 DEG C. Through bonding, heat treatment peeling, CMP removal of the surface damage layer and other processes, the piezoelectric single crystal thin film layer 6 is transferred to the insulating layer 5 to obtain the composite structure of the surface acoustic wave device substrate provided in the application.

[0058] The composite structure of the surface acoustic wave device substrate prepared by the embodiment can effectively absorb the lithography light, weaken the scattering and reflection during lithography, effectively prevent the resistivity of the surface acoustic wave device substrate from decreasing, reduce the loss of the surface acoustic wave device substrate, and improve the working stability of the surface acoustic wave device.

[0059] Embodiment 2:

[0060] Please refer to Figure 1 and Figure 3 The composite structure of the surface acoustic wave device substrate provided in the application comprises, from bottom to top, a single crystal silicon substrate layer 1, a polycrystalline silicon layer 2, an absorbing layer 4, an insulating layer 5 and a piezoelectric single crystal thin film layer 6.

[0061] For example, the single crystal silicon substrate layer 1 is a high-resistance silicon substrate, the absorbing layer 4 is porous silicon, the insulating layer 5 is silicon oxide, and the piezoelectric single crystal thin film layer 6 is lithium tantalate.

[0062] The absorbing layer 4 is used to absorb the incident light during lithography. Through the absorbing layer 4, the ultraviolet band lithography light can be effectively absorbed before reaching the surface of the polycrystalline silicon layer 2, the scattering and reflection during lithography are weakened, the resolution of lithography is improved, the surface parasitic conductance effect is inhibited, and the performance and working stability of the prepared device are improved.

[0063] The preparation method of the composite structure in the embodiment comprises the following steps:

[0064] S1, preparing a single crystal silicon substrate layer 1.

[0065] For example, the single crystal silicon substrate layer 1 is a high-resistance silicon substrate, and the resistance of the high-resistance silicon substrate is greater than 300 Ω·cm.

[0066] S2, cleaning the single crystal silicon substrate layer 1 to obtain a smooth surface, and generating a polycrystalline silicon layer 2 with a thickness of about 1200 nm on the single crystal silicon substrate layer 1 by low-pressure chemical vapor deposition in a silane gas atmosphere at a temperature of 600-680 DEG C and a pressure of 0.3 Torr.

[0067] The polycrystalline silicon layer 2 is used to provide carrier traps and inhibit the parasitic surface conductance effect.

[0068] In an exemplary embodiment, the composite structure of the surface acoustic wave device substrate can further comprise a trap-rich layer 3 disposed at the interface between the single crystal silicon substrate layer 1 and the polycrystalline silicon layer 2, and the trap-rich layer 3 can have a thickness of 50-200 nm. The trap-rich layer 3 can be provided to prevent the polycrystalline silicon layer 2 from providing insufficient trap density, and the trap-rich layer 3 can provide greater defect density relative to the polycrystalline silicon layer 2, thereby enhancing the trapping of free carriers and improving the resistivity of the surface acoustic wave device substrate.

[0069] Based on this, after step S2, the method for preparing the composite structure can further comprise: preparing a trap-rich layer 3 having a thickness of 50-200 nm at the interface between the polycrystalline silicon layer 2 and the single crystal silicon substrate layer 1 by performing helium ion implantation on the polycrystalline silicon layer 2.

[0070] S3, preparing an absorption layer 4 on the polycrystalline silicon layer 2.

[0071] The absorption layer 4 can be porous silicon, which can improve the light absorption rate of the lithography light due to the light trapping effect of the porous silicon, and the pore size of the polycrystalline silicon is less than 50 nm.

[0072] S4, preparing an insulating layer 5 on the absorption layer 4.

[0073] The insulating layer 5 can provide temperature compensation and a smooth bonding interface.

[0074] For example, the insulating layer 5 can be silicon oxide.

[0075] S5, preparing a piezoelectric single crystal thin film layer 6 and transferring the piezoelectric single crystal thin film layer 6 to the insulating layer 5.

[0076] For example, the insulating layer 5 can be subjected to CMP processing to obtain a smooth surface before the piezoelectric single crystal thin film layer 6 is transferred to the insulating layer 5.

[0077] The piezoelectric single crystal thin film layer 6 can be lithium tantalate, and an oxide layer can be deposited on the piezoelectric single crystal thin film layer 6. The piezoelectric single crystal thin film layer 6 is transferred to the insulating layer 5 through bonding, grinding and thinning processes, thereby obtaining another composite structure of the surface acoustic wave device substrate provided by the present application.

[0078] The composite structure of the surface acoustic wave device substrate prepared by the present embodiment can effectively absorb lithography light, reduce scattering and reflection during lithography, effectively prevent the resistivity of the surface acoustic wave device substrate from decreasing, reduce the loss of the surface acoustic wave device substrate, and improve the working stability of the surface acoustic wave device.

[0079] Embodiment 3:

[0080] Please refer toFigure 1 and Figure 4 The application provides a composite structure of a surface acoustic wave device substrate and a preparation method thereof. The composite structure comprises, from bottom to top, a single crystal silicon substrate layer 1, a polysilicon layer 2, an absorption layer 4, an insulating layer 5 and a piezoelectric single crystal thin film layer 6.

[0081] For example, the single crystal silicon substrate layer 1 is a high-resistance silicon substrate, the absorption layer 4 is made of amorphous silicon, the insulating layer 5 is made of silicon oxide, and the piezoelectric single crystal thin film layer 6 is made of lithium niobate.

[0082] The absorption layer 4 is used to absorb incident light during photolithography. Through the absorption layer 4, the photolithography light in the ultraviolet band can be effectively absorbed before reaching the surface of the polysilicon layer 2, the scattering and reflection during photolithography are weakened, the resolution of photolithography is improved, the surface parasitic conductance effect is inhibited, and the performance and working stability of the prepared device are improved.

[0083] The preparation method of the composite structure in the embodiment comprises the following steps.

[0084] S1, preparing the single crystal silicon substrate layer 1.

[0085] For example, the single crystal silicon substrate layer 1 is a high-resistance silicon substrate, and the resistance of the high-resistance silicon substrate is greater than 300 Ω·cm.

[0086] S2, cleaning the single crystal silicon substrate layer 1 to obtain a smooth surface, and generating a polysilicon layer 2 with a thickness of about 1200 nm on the single crystal silicon substrate layer 1 in a silane gas atmosphere with a temperature of 600-680 ℃ and a pressure of 0.3 Torr by low-pressure chemical vapor deposition.

[0087] The polysilicon layer 2 is used to provide carrier traps and inhibit the parasitic surface conductance effect.

[0088] In an example embodiment, the composite structure of the surface acoustic wave device substrate can further comprise a trap-rich layer 3 arranged at the junction of the single crystal silicon substrate layer 1 and the polysilicon layer 2. The thickness of the trap-rich layer 3 can be 50-200 nm. The arrangement of the trap-rich layer 3 can prevent the insufficient trap density provided by the polysilicon layer 2. Compared with the polysilicon layer 2, the trap-rich layer 3 can provide a larger defect density, enhance the capture of free carriers, and improve the resistivity of the surface acoustic wave device substrate.

[0089] Based on this, after step S2, the preparation method of the composite structure can further comprise: preparing a trap-rich layer 3 with a thickness of 50-200 nm at the junction of the polysilicon layer 2 and the single crystal silicon substrate layer 1 by introducing a carbon-containing gas into the polysilicon layer 2.

[0090] S3, preparing the absorption layer 4 on the polysilicon layer 2.

[0091] The absorption layer 4 can be amorphous silicon. In order to prevent insufficient absorption efficiency, a plurality of protrusions are prepared on the surface of the amorphous silicon by etching, and are distributed at equal intervals, so as to increase the scattering of the lithography light. The plurality of grooves are in V-shaped or inverted-pyramid-shaped structure, and the interval between the plurality of grooves is not less than 1 um.

[0092] S4, preparing the insulating layer 5 on the absorption layer 4.

[0093] The insulating layer 5 can play a role of temperature compensation, and can provide a smooth bonding interface.

[0094] For example, the insulating layer 5 can be silicon oxide.

[0095] S5, preparing the piezoelectric single crystal thin film layer 6, and transferring the piezoelectric single crystal thin film layer 6 to the insulating layer 5.

[0096] For example, the insulating layer 5 can be subjected to CMP treatment before the transferring, so as to obtain a smooth surface, and then the prepared piezoelectric single crystal thin film layer 6 is transferred to the insulating layer 5.

[0097] The piezoelectric single crystal thin film layer 6 can be lithium niobate, and the piezoelectric single crystal thin film layer 6 can be subjected to helium ion implantation. The energy range of the helium ion implantation is 10 kev-2000 kev, the dose of the helium ion implantation is 1e15-1e17, and the annealing temperature is 150-350. Through the bonding, the heat treatment peeling, the CMP removal of the surface damage layer and other processes, the piezoelectric single crystal thin film layer 6 is transferred to the insulating layer 5, so as to obtain another composite structure of the surface acoustic wave device substrate provided by the application.

[0098] The composite structure of the surface acoustic wave device substrate prepared by the embodiment can effectively absorb the lithography light, weaken the scattering and reflection during the lithography, effectively prevent the resistivity of the surface acoustic wave device substrate from decreasing, reduce the loss of the surface acoustic wave device substrate, and improve the working stability of the surface acoustic wave device.

[0099] Embodiment 4:

[0100] Please refer to Figure 1 and Figure 5 The composite structure of the surface acoustic wave device substrate provided by the application comprises, from bottom to top, a single crystal silicon substrate layer 1, a polycrystalline silicon layer 2, an absorption layer 4, an insulating layer 5 and a piezoelectric single crystal thin film layer 6.

[0101] For example, the single crystal silicon substrate layer 1 is a high-resistance silicon substrate, the absorption layer 4 is amorphous silicon, the insulating layer 5 is silicon nitride, and the piezoelectric single crystal thin film layer 6 is lithium tantalate.

[0102] The absorption layer 4 is used for absorbing the incident light during the photolithography. The absorption layer 4 can effectively absorb the photolithography light in the ultraviolet band before the light reaches the surface of the polysilicon layer 2, weaken the scattering and reflection during the photolithography, improve the resolution of the photolithography, and inhibit the surface parasitic conductance effect, thereby improving the performance and working stability of the prepared device.

[0103] The preparation method of the composite structure in the embodiment includes the following steps:

[0104] S1, preparing a single crystal silicon substrate layer 1.

[0105] In an example, the single crystal silicon substrate layer 1 is a high-resistance silicon substrate, and the resistance of the high-resistance silicon substrate is greater than 300 Ω·cm.

[0106] S2, cleaning the single crystal silicon substrate layer 1 to obtain a smooth surface, and generating a polysilicon layer 2 with a thickness of about 1200 nm on the single crystal silicon substrate layer 1 in a silane gas atmosphere with a temperature of 600-680 ℃ and a pressure of 0.3 Torr by a low-pressure chemical vapor deposition method.

[0107] The polysilicon layer 2 is used to provide carrier traps and inhibit the parasitic surface conductance effect.

[0108] In an example, the composite structure of the surface acoustic wave device substrate further includes a trap-rich layer 3 arranged at the junction of the single crystal silicon substrate layer 1 and the polysilicon layer 2. The thickness of the trap-rich layer 3 can be 50-200 nm. The trap-rich layer 3 can prevent the polysilicon layer 2 from providing insufficient trap density. Compared with the polysilicon layer 2, the trap-rich layer 3 can provide greater defect density, enhance the capture of free carriers, and improve the resistivity of the surface acoustic wave device substrate.

[0109] Based on this, after step S2, the preparation method of the composite structure further includes: preparing a trap-rich layer 3 with a thickness of 50-200 nm at the junction of the polysilicon layer 2 and the single crystal silicon substrate layer 1 by introducing a nitrogen-containing gas into the polysilicon layer 2.

[0110] S3, preparing an absorption layer 4 on the polysilicon layer 2.

[0111] The absorption layer 4 can be amorphous silicon. In order to prevent insufficient absorption efficiency, a plurality of protrusions are arranged at equal intervals on the surface of the amorphous silicon by etching to increase the scattering of the photolithography light. The plurality of protrusions have a conical peak or a strip structure, and the interval between the plurality of protrusions is not less than 1 um.

[0112] S4, preparing an insulating layer 5 on the absorption layer 4.

[0113] The insulating layer 5 can play a temperature compensation role and provide a smooth bonding interface.

[0114] For example, the insulating layer 5 can be silicon nitride.

[0115] S5, preparing a piezoelectric single crystal thin film layer 6, and transferring the piezoelectric single crystal thin film layer 6 to the insulating layer 5.

[0116] For example, the insulating layer 5 can be subjected to CMP treatment to obtain a smooth surface before the transferring, and then the prepared piezoelectric single crystal thin film layer 6 is transferred to the insulating layer 5.

[0117] The piezoelectric single crystal thin film layer 6 can be lithium tantalate, and the piezoelectric single crystal thin film layer 6 is subjected to hydrogen ion implantation, the energy range of the hydrogen ion implantation is 10 kev-2000 kev, the dose of the hydrogen ion implantation is 1e15-1e17, the annealing temperature is 150-350℃, and the piezoelectric single crystal thin film layer 6 is transferred to the insulating layer 5 through the processes of bonding, thermal treatment peeling, and CMP removal of the surface damage layer, to obtain another composite structure of the surface acoustic wave device substrate provided by the application.

[0118] The composite structure of the surface acoustic wave device substrate prepared by the embodiment can effectively absorb the lithography light, weaken the scattering and reflection during the lithography, effectively prevent the resistivity of the surface acoustic wave device substrate from decreasing, reduce the loss of the surface acoustic wave device substrate, and improve the working stability of the surface acoustic wave device.

[0119] The above is only a preferred embodiment of the application, and is not used to limit the application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A composite structure for a surface acoustic wave (SAW) device substrate, characterized in that, The composite structure comprises, from bottom to top, a single-crystal silicon substrate layer (1), a polycrystalline silicon layer (2), an absorption layer (4), an insulating layer (5), and a piezoelectric single-crystal thin film layer (6). The absorption layer (4) is used to absorb incident light during photolithography. When the absorption layer (4) is an amorphous silicon layer, multiple grooves or protrusions are provided on the absorption layer (4). The multiple grooves or protrusions are distributed at equal intervals, and the interval between the grooves or protrusions is not less than 1 μm. The insulating layer (5) is selected from amorphous aluminum nitride, silicon oxide, and silicon nitride, and is used to provide a bonding interface.

2. The composite structure of a surface acoustic wave device substrate according to claim 1, characterized in that, The absorption layer (4) is made of porous silicon or amorphous silicon.

3. The composite structure of a surface acoustic wave device substrate according to claim 1, characterized in that, The thickness of the absorption layer (4) is not less than 100 nm. When the absorption layer (4) is made of amorphous silicon, the spacing between the multiple grooves or protrusions prepared on the absorption layer (4) is not less than 1 μm, and the aspect ratio of the grooves is greater than 1.

4. The composite structure of a surface acoustic wave device substrate according to claim 1, characterized in that, A trap-rich layer (3) is provided at the junction of the monocrystalline silicon substrate layer (1) and the polycrystalline silicon layer (2), and the thickness of the trap-rich layer (3) is 50nm to 200nm.

5. The composite structure of a surface acoustic wave device substrate according to claim 1, characterized in that, The insulating layer (5) is selected from one of amorphous aluminum nitride, silicon oxide, and silicon nitride. The piezoelectric single crystal thin film layer (6) is selected from any one of lithium niobate and lithium tantalate. The single crystal silicon substrate layer (1) is a high-resistivity silicon substrate with a resistance greater than 300 Ω·cm.

6. A method for fabricating a surface acoustic wave (SAW) device substrate composite structure, characterized in that, include: Prepare a single-crystal silicon substrate layer (1), and deposit a polycrystalline silicon layer (2) on the single-crystal silicon substrate layer (1); An absorption layer (4) is prepared on the polycrystalline silicon layer (2), and the upper surface of the absorption layer (4) is selectively etched; an insulating layer (5) is prepared on the absorption layer (4); Prepare a piezoelectric single crystal thin film layer (6) and transfer the piezoelectric single crystal thin film layer (6) onto the insulating layer (5); When the absorption layer (4) is an amorphous silicon layer, multiple equidistant protrusions or grooves are prepared on the surface of the amorphous silicon layer by etching, and the interval between the grooves or protrusions is not less than 1 μm; the insulating layer (5) is selected from amorphous aluminum nitride, silicon oxide, and silicon nitride.

7. The method for fabricating a surface acoustic wave device substrate composite structure according to claim 6, characterized in that, Depositing a polycrystalline silicon layer (2) on the monocrystalline silicon substrate (1) includes: generating a polycrystalline silicon layer (2) with a thickness of about 1200 nm on the monocrystalline silicon substrate (1) in a silane gas atmosphere at a temperature of 600 to 680 °C and a pressure of 0.3 Torr by low-pressure chemical vapor deposition.

8. The method for fabricating a surface acoustic wave device substrate composite structure according to claim 6, characterized in that, The method further includes: preparing a trap-rich layer (3) at the junction of the polycrystalline silicon layer (2) and the monocrystalline silicon substrate layer (1) by ion implantation or by introducing carbon- or nitrogen-containing gas.

9. The method for fabricating a surface acoustic wave device substrate composite structure according to claim 8, characterized in that, The transfer method includes any one of ion implantation and bond stripping, or bonding and grinding thinning.

10. The method for fabricating a surface acoustic wave device substrate composite structure according to claim 9, characterized in that, The transfer method involves ion implantation and bond stripping. The type of ions implanted into the piezoelectric single-crystal thin film layer (6) is hydrogen or helium ions. The energy range of the implanted ions is 10 keV to 2000 keV, and the dose of the implanted ions is 1 eV. 15 ~1e 17 The annealing temperature is 150℃~350℃.

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