Heterostructure substrate based on spinel ceramic substrate and preparation method and application thereof

Abstract

The present invention belongs to the field of optoelectronic integration technology, and relates to a heterostructure substrate based on a spinel ceramic substrate, and a preparation method and application thereof, wherein the preparation method comprises the following steps: coating a first-class diamond film on the surface of a spinel ceramic substrate; bonding one side of a donor piezoelectric substrate to the surface of a second-class diamond film, and bonding the other side of the donor piezoelectric substrate to a supporting substrate; bonding the surface of the first-class diamond film to the surface of the second-class diamond film; using an intelligent cutting process to peel off the supporting substrate from a portion of the donor piezoelectric substrate to form an LN or LT piezoelectric film, and obtaining a diamond-like film / piezoelectric film composite heterogeneous substrate, which can be effectively used in high-frequency radio frequency chip filters. Compared with the prior art, the method of the present invention can effectively improve the thermal conductivity, thermal stability and electrical properties of the substrate, and has a high application value.

Description

Technical Field

[0001] The invention belongs to the technical field of optoelectronic integration, and relates to a heterostructure substrate based on a spinel ceramic substrate, and a preparation method and application thereof. Background Art

[0002] Lithium niobate (LiNbO3) and lithium tantalate (LiTaO3) are piezoelectric materials widely used in high-frequency RF chips, surface acoustic wave filters, electro-optic modulators and other fields. In the prior art, ion beam stripping technology is often used to transfer lithium niobate or lithium tantalate films to silicon-based substrates to form corresponding piezoelectric films. However, the difference in thermal expansion coefficients between silicon-based substrates and lithium niobate or lithium tantalate films often leads to stress during high-temperature processing, affecting the stability of the substrate and the reliability of the device.

[0003] Diamond-like carbon films, as an ideal interface material, have great potential in improving substrate performance due to their excellent thermal conductivity, thermal stability and electrical properties. The preparation of traditional diamond-like carbon films is relatively complicated and faces the problem of high cost. How to combine diamond-like carbon films with piezoelectric materials (such as lithium niobate and lithium tantalate) to form a heterogeneous substrate with higher performance is one of the current research hotspots. Summary of the invention

[0004] The purpose of the present invention is to provide a heterogeneous structure substrate based on a spinel ceramic substrate, and its preparation method and application. The present invention provides a method for preparing a heterogeneous substrate by preparing a diamond-like film on a spinel ceramic substrate and combining it with a piezoelectric material film, thereby improving the thermal conductivity, thermal stability and electrical properties of the substrate, providing a more superior substrate material for applications in high-frequency radio frequency chips and other fields, solving the stress problem caused by differences in the thermal expansion coefficients of substrate materials in the prior art, thereby realizing the preparation of high-performance substrates.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] The first object of the present invention is to provide a method for preparing a heterostructure substrate based on a spinel ceramic substrate, the preparation method comprising the following steps:

[0007] Coating a first-type diamond film on the surface of a spinel ceramic substrate;

[0008] bonding one side of the donor piezoelectric substrate to the surface of the second diamond-like film, and bonding the other side of the donor piezoelectric substrate to the supporting substrate;

[0009] The surface of the first type diamond film is bonded to the surface of the second type diamond film;

[0010] The supporting substrate and a part of the donor piezoelectric substrate are peeled off by using an intelligent cutting process to form LN and / or LT piezoelectric films, thereby obtaining a diamond-like carbon film / piezoelectric film composite heterogeneous substrate.

[0011] Furthermore, the smart cutting process is an ion implantation stripping process, including the following parameters:

[0012] Cutting temperature: 25℃-300℃, cutting speed: 10-20 mm / min, laser cutting or diamond wire cutting, both of which are achieved by CNC machine tools, coolant flow rate: 5-10 L / min, using water-based coolant; the diamond wire cutting tool adopts a diamond tool, and the tool surface coating is TiN or TiAlN coating;.

[0013] Furthermore, the energy of the smart cutting process is 50 to 250 keV, and the dose range is 1×10 16 / cm2 to 1×10 17 Pieces / square centimeter.

[0014] Furthermore, the first type diamond film and the second type diamond film are prepared by chemical vapor deposition, that is, the first type diamond film is plated on the surface of the spinel ceramic substrate by chemical vapor deposition, and one side of the donor piezoelectric substrate is bonded to the surface of the second type diamond film by chemical vapor deposition.

[0015] Furthermore, the other side of the donor piezoelectric substrate is bonded to the support substrate by chemical vapor deposition.

[0016] Furthermore, the surface of the first type diamond film and the surface of the second type diamond film are bonded by high temperature and high pressure (HPHT) bonding.

[0017] Furthermore, the precursor gases used in the chemical vapor deposition method are methane and hydrogen, the ratio of methane to hydrogen is 1:10~1:100, the temperature is 200℃~900℃, the pressure is 1~10 Torr, the RF power is 50W~500W, and the deposition time is 30min~2h.

[0018] Furthermore, the high temperature and high pressure (HPHT) bonding temperature is above 1000° C., the pressure is 500-550 GPa, and the bonding time is 2-4 hours.

[0019] Furthermore, the donor piezoelectric substrate is one or more of a lithium niobate single crystal film or a lithium tantalate single crystal film.

[0020] Furthermore, the supporting substrate is a silicon substrate.

[0021] Furthermore, the thickness of the first type diamond film and the second type diamond film ranges from 50 to 200 nanometers; the thickness of the spinel ceramic substrate is 300 to 500 microns; the thickness of the donor piezoelectric substrate is 100 to 500 microns; and the thickness of the supporting substrate is 100 to 500 microns.

[0022] Furthermore, the thickness of the LN and / or LT piezoelectric film is 1 to 10 microns.

[0023] The second object of the present invention is to provide a heterostructure substrate based on a spinel ceramic substrate, wherein the heterostructure substrate comprises a spinel ceramic substrate, a first diamond-like film, a second diamond-like film, and an LN and / or LT piezoelectric film arranged in sequence.

[0024] The third object of the present invention is to provide an application of a heterostructure substrate based on a spinel ceramic substrate, and to use the heterostructure substrate for a high-frequency radio frequency chip filter.

[0025] Compared with the prior art, the present invention has the following characteristics:

[0026] 1) The heterostructure substrate based on the spinel ceramic substrate provided by the present invention provides a method for preparing a heterogeneous substrate by preparing a diamond-like film on the spinel ceramic substrate and combining it with a piezoelectric material film, thereby improving the thermal conductivity, thermal stability and electrical properties of the substrate, providing a more superior substrate material for applications in high-frequency radio frequency chips and other fields, solving the stress problem caused by the difference in thermal expansion coefficient of the substrate material in the prior art, thereby realizing the preparation of high-performance substrates.

[0027] 2) The method for preparing a heterogeneous structure substrate based on a spinel ceramic substrate provided by the present invention effectively reduces the stress caused by the difference in thermal expansion coefficients, and uses an intelligent cutting process to achieve high-performance, low-cost heterogeneous substrate preparation. The obtained heterogeneous substrate can be further used in high-frequency RF chip filters and other application fields. Through the preparation steps, the final heterogeneous substrate structure has excellent thermal stability, thermal conductivity and electrical properties, and is suitable for high-frequency, high-power applications, such as RF chip filters.

[0028] 3) The preparation method of the heterostructure substrate based on the spinel ceramic substrate provided by the present invention improves the traditional intelligent cutting process. By optimizing the cutting temperature, cutting speed, cutting method, etc., it controls thermal stress, reduces crack propagation, improves cutting accuracy, reduces errors, reduces damage, increases cooling effect, improves wear resistance, reduces heat accumulation, and reduces friction. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1A schematic diagram of a process for preparing a heterostructure substrate based on a spinel ceramic substrate according to the present invention;

[0030] Figure 2 It is a schematic structural diagram of a spinel ceramic substrate formed with a diamond-like film layer and a first diamond-like film of the present invention;

[0031] Figure 3 This is a schematic diagram of the donor piezoelectric ceramic (donor piezoelectric substrate)-support substrate structure formed with a diamond-like thin film layer of the present invention;

[0032] Figure 4 The present invention is a schematic diagram of the preparation structure of a heterostructure substrate based on a spinel ceramic substrate.

[0033] Among them, 1. spinel ceramic substrate, 2. first type diamond film, 3. second type diamond film, 4. donor piezoelectric substrate, 5. supporting substrate, 6. LN and / or LT piezoelectric film. DETAILED DESCRIPTION

[0034] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the accompanying drawings and the following embodiments are only used to illustrate the present invention, rather than to limit the present invention. It should be pointed out that for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0035] Any features such as preparation methods, materials, structures or composition ratios that are not clearly described in this technical solution shall be deemed as common technical features disclosed in the prior art.

[0036] Example 1

[0037] This embodiment provides a heterostructure substrate based on a spinel ceramic substrate, comprising the following steps:

[0038] Step 1: Substrate Preparation

[0039] 1.1 A spinel ceramic substrate 1 with a size of 2 inches and a thickness of 500 microns is provided, and the surface is cleaned to ensure that there are no pollutants and impurities on the surface.

[0040] 1.2 A layer of diamond-like carbon film is grown on the surface of the spinel ceramic substrate 1 by chemical vapor deposition (CVD) as the first diamond-like carbon film 2, and the film thickness is 200 nanometers. The precursor gases used are methane and hydrogen, and the quality and crystal structure of the film are controlled by adjusting the flow ratio and deposition temperature. The preferred flow ratio is a flow ratio of methane to hydrogen of 1:100, a deposition temperature of 850°C, a chemical vapor deposition pressure of 6 Torr, an RF power of 200 W, and a deposition time of 1 hour.

[0041] Step 2: Bonding of diamond-like carbon film to piezoelectric substrate

[0042] 2.1 Support substrate 5 uses a single crystal silicon substrate with a silicon oxide film coated on the surface. The thickness of the support substrate 5 is 300 microns.

[0043] 2.2 Select lithium niobate (LN) or lithium tantalate (LT) film as the donor piezoelectric substrate 4. The selected material in this embodiment is prepared by a standard crystal growth method (such as a melting method), and is bonded to the support substrate 5 on the support substrate 5 to obtain a lithium niobate (LN) film with a thickness of 100 microns, which is the donor piezoelectric substrate 4. The second surface of the donor piezoelectric substrate 4 is bonded to the support substrate 5.

[0044] 2.3 A layer of diamond-like film with a thickness of 50 nanometers is grown on the first surface of the donor piezoelectric substrate 4 using the same CVD technology as in the above steps, namely, the second diamond-like film 3.

[0045] 2.4 The second type diamond film 3 is placed facing the spinel ceramic substrate 1 and the first type diamond film 2, and the surface of the second type diamond film 3 bonded to the donor piezoelectric substrate 4 is bonded to the first type diamond film 2 on the spinel ceramic substrate 1, and high temperature and high pressure method (HPHT) bonding under high temperature and high pressure conditions (temperature 1200°C, pressure 510 GPa, bonding time 2 to 4 hours) is used to ensure that the bonding interface has good bonding strength.

[0046] Step 3: Peeling off and film transfer support substrate 5

[0047] 3.1 The support substrate 5 and a part of the donor piezoelectric substrate 4 are peeled off by a composite crystal cutting process to obtain an LN or LT piezoelectric film 6 with piezoelectric properties, and the thickness of the obtained LN or LT piezoelectric film 6 is 1 to 10 microns. The intelligent cutting process is an ion implantation peeling process, including the following parameters: cutting temperature: 25°C-300°C, cutting speed: 10-20 mm / min, laser cutting or diamond wire cutting, both of which are implemented by CNC machine tools, coolant flow rate: 5-10 L / min, using water-based coolant (adding anti-gasification agent); the diamond wire cutting tool is a diamond tool, the tool surface coating is TiN or TiAlN coating, and it is implemented by CNC machine tools; the energy of the intelligent cutting process is 50 to 250 keV, and the dose range is 1×10 16 / cm2 to 1×10 17 Pieces / square centimeter

[0048] Step 4: Formation of the final foreign substrate

[0049] 4.1 After removing the supporting substrate 5 and retaining the LN or LT film portion, a heterostructure substrate based on a spinel ceramic substrate is finally formed, specifically a diamond-like carbon film / lithium niobate (LN) or lithium tantalate (LT) film heterostructure substrate based on a spinel ceramic substrate.

[0050] This embodiment demonstrates a high-performance heterogeneous substrate prepared by using a diamond-like carbon film to enhance substrate performance and a smart cutting process, which has good electrical properties, thermal conductivity and thermal stability.

[0051] Comparative Example 1

[0052] This comparative example provides a heterostructure substrate based on a spinel ceramic substrate. The difference between this comparative example and Example 1 is that in step 3.1 of this comparative example, a conventional smart cutting process (smartcut technology) is used to peel off a portion of the supporting substrate 5 and the donor piezoelectric substrate 4. The conventional smart cutting process (smartcut technology) includes the following parameters: cutting temperature: above about 300°C, cutting speed: >50 mm / min, diamond cutting, coolant flow rate: 3 - 5 L / min, ordinary oil-based coolant is used, the tool is a diamond tool, the tool surface is uncoated, and it is implemented using ordinary smart cutting system equipment.

[0053] The heterostructure substrate prepared by the method of Comparative Example 1 has cracks on the spinel surface and low wear resistance due to the cutting temperature and cutting speed settings. However, the heterostructure substrate prepared by the method of Example 1 has no cracks on the spinel surface, high wear resistance, and good electrical properties, thermal conductivity and thermal stability.

[0054] Electrodes were formed on the heterostructure substrates of Example 1 and Comparative Example 1 to obtain filters and verify the characteristics of the filters. Table 1 lists various parameters.

[0055] Table 1: Characteristics of filters obtained from the heterostructure substrates of Example 1 and Comparative Example 1.

[0056]

[0057] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing a heterostructure substrate based on a spinel ceramic substrate, characterized in that: The preparation method comprises the following steps: Coating a first-type diamond film on the surface of a spinel ceramic substrate; bonding one side of the donor piezoelectric substrate to the surface of the second diamond-like film, and bonding the other side of the donor piezoelectric substrate to the supporting substrate; The surface of the first type diamond film is bonded to the surface of the second type diamond film; The supporting substrate and a part of the donor piezoelectric substrate are peeled off by using an intelligent cutting process to form LN and / or LT piezoelectric films, thereby obtaining a diamond-like carbon film / piezoelectric film composite heterogeneous substrate.

2. The method for preparing a heterostructure substrate based on a spinel ceramic substrate according to claim 1, characterized in that: The smart cutting process is an ion implantation stripping process, including the following parameters: Cutting temperature: 25℃-300℃, cutting speed: 10-20 mm / min, laser cutting or diamond wire cutting, both of which are implemented by CNC machine tools, coolant flow rate: 5-10 L / min, using water-based coolant; the diamond wire cutting tool adopts a diamond tool, and the tool surface coating is TiN or TiAlN coating; the energy of the intelligent cutting process is 50 to 250 keV, and the dose range is 1×10 16 / cm2 to 1×10 17 Pieces / square centimeter.

3. The method for preparing a heterostructure substrate based on a spinel ceramic substrate according to claim 1, characterized in that: The first type diamond film and the second type diamond film are prepared by chemical vapor deposition; The other side of the donor piezoelectric substrate is bonded to the support substrate by chemical vapor deposition; The surface of the first type diamond film and the surface of the second type diamond film are bonded by high temperature and high pressure bonding.

4. The method for preparing a heterostructure substrate based on a spinel ceramic substrate according to claim 1, characterized in that: The donor piezoelectric substrate is one or more of a lithium niobate single crystal film and a lithium tantalate single crystal film.

5. The method for preparing a heterostructure substrate based on a spinel ceramic substrate according to claim 1, characterized in that: The supporting substrate is a silicon substrate.

6. The method for preparing a heterostructure substrate based on a spinel ceramic substrate according to claim 1, characterized in that: The thickness of the first type diamond film and the second type diamond film ranges from 50 to 200 nanometers; The spinel ceramic substrate has a thickness of 300 to 500 microns; The thickness of the donor piezoelectric substrate is 100 to 500 microns; The thickness of the support substrate is 100-500 microns.

7. The method for preparing a heterostructure substrate based on a spinel ceramic substrate according to claim 6, characterized in that: The thickness of the LN and / or LT piezoelectric film is 1 to 10 microns.

8. A heterostructure substrate based on a spinel ceramic substrate prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The heterostructure substrate includes a spinel ceramic substrate, a first diamond-like film, a second diamond-like film, and an LN and / or LT piezoelectric film which are arranged in sequence.

9. An application of a heterostructure substrate based on a spinel ceramic substrate prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The heterostructure substrate is used for high-frequency radio frequency chip filters.

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