C-axis preferentially oriented yaln thin film, and preparation method and application thereof

Abstract

The application provides a C-axis preferred orientation YAlN film and a preparation method and application thereof. The preparation method comprises the following steps: (1) placing a substrate in a vacuumized cavity, and heating the substrate to an ion implantation temperature; (2) introducing a first gas into the cavity until the gas pressure in the cavity reaches a first working pressure, and performing ion implantation treatment on the surface of the substrate; and (3) introducing a second working gas into the cavity until the gas pressure in the cavity reaches a second working pressure, and depositing a YAlN film on the surface of the substrate after the ion implantation treatment by means of reactive magnetron sputtering. The application combines interface regulation induced by ion implantation with the thin film deposition process of reactive magnetron sputtering, and the two processes work together to form stable C-axis preferred orientation YAlN film deposition. Through the optimization process of multiple steps, the cost of film preparation is significantly reduced, and the C-axis orientation degree of the film is effectively ensured.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, specifically to the preparation of YAlN thin films, and more particularly to a C-axis preferred orientation YAlN thin film, its preparation method, and its applications. Background Technology

[0002] With the rapid development of 5G communication technology, high-frequency acoustic filters have become core components in wireless communication systems. Piezoelectric thin films, as an indispensable key material in the manufacture of high-frequency acoustic filters, directly determine the overall performance of the filter. Scandium (Sc)-doped aluminum nitride (AlN) thin films, due to their combination of high voltage response and low dielectric loss, have become one of the core materials for the manufacture of current high-frequency radio frequency filters. However, Sc metal, as a high-value rare earth element, is expensive and its resources are limited and non-renewable. Therefore, the use of yttrium (Y), a rare earth element with lower cost, as a dopant element to prepare YAlN thin films has received widespread attention in recent years.

[0003] The electromechanical coupling coefficient of YAlN thin films can reach 8%~10%. However, since the radius of Y atoms is larger than that of Sc atoms, the lattice distortion of YAlN is more significant, which easily leads to a decrease in the preferred orientation of the "principal crystal axis" (C axis) perpendicular to the atomic close-packed basal plane.

[0004] CN115036310A discloses a CMOS device based on a GaN / YAlN / GaN heterojunction and its fabrication method, comprising: growing a 3μm~4.5μm buffer layer on a substrate using MOCVD; growing a 150nm~480nm GaN n-type channel layer on the buffer layer using MOCVD; growing a 15nm~30nm YAlN barrier layer with an Al composition of 85%~94% using MOCVD on the GaN n-type channel layer; growing a 20nm~40nm undoped GaN p-type channel layer on the YAlN barrier layer using MOCVD; and growing a 70nm~80nm p-GaN layer on the GaN p-type channel layer using MOCVD. This invention inserts an undoped GaN p-channel layer between the YAlN barrier layer and the p-GaN layer, which effectively reduces the impact of ionized impurity scattering on charge carriers, improves the mobility of the two-dimensional hole gas 2DHG, and effectively increases the speed of the p-type field-effect transistor (p-FET). Lattice matching can be achieved between YAlN and GaN, effectively improving the heterojunction state, reducing the impact of interface scattering on charge carriers, increasing the mobility of both the two-dimensional electron gas 2DEG and the two-dimensional hole gas 2DHG, and effectively improving the switching characteristics of the device.

[0005] CN118866988A discloses a low work function grooved anode YAlN / GaN heterojunction Schottky diode, comprising growing an AlN buffer layer, a GaN channel layer, and an AlN insertion layer sequentially from bottom to top on the upper surface of a substrate; and growing a YAlN heterojunction on the upper surface of the AlN insertion layer using molecular beam epitaxy. x Al 1-x The invention employs YAlN material for both the first and second barrier layers. YAlN material can achieve near-lattice matching of in-plane lattice constants and strain-free material growth with the GaN master quantum well, thereby reducing the dislocation density in the active region of the device, reducing dislocation scattering, and improving the differential negative resistance effect of the device.

[0006] CN115064620A discloses a high-efficiency deep ultraviolet light-emitting diode with a stepped YAlN / AlGaN superlattice p-type layer and its fabrication method. The stepped YAlN / AlGaN superlattice p-type layer adopts a three-order stepped YAlN / AlGaN superlattice, with the following parameters for each order: the first order superlattice has 7 to 10 periods, the Al composition of the YAlN material in each period ranges from 0.6 to 0.8, and the thickness is 3 nm to 7 nm; the Al composition of the AlGaN material in each period ranges from 0.5 to 0.8, and the thickness is 1 nm. The second-order superlattice has 7-10 periods, with each period containing YAlN material having an Al composition ranging from 0.6 to 0.8 and a thickness of 3-7 nm, and each period containing AlGaN material having an Al composition ranging from 0.3 to 0.5 and a thickness of 1-4 nm. The third-order superlattice also has 7-10 periods, with each period containing YAlN material having an Al composition ranging from 0.6 to 0.8 and a thickness of 3-7 nm, and each period containing AlGaN material having an Al composition ranging from 0.1 to 0.3 and a thickness of 1-4 nm. This invention effectively reduces stress in the epitaxial layer through a step-like composition with decreasing Al composition, thereby improving the epitaxial quality of the crystal.

[0007] In existing technologies, the introduction of YAlN thin films typically relies on the introduction of a buffer layer, which further reduces the preferred orientation of the film. Therefore, providing a method for preparing YAlN thin films with high c-axis preferred orientation is not only of significant scientific importance but also has substantial economic value. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a C-axis preferred-oriented YAlN thin film, its preparation method, and its applications. This invention organically combines ion implantation-induced interface control with reactive magnetron sputtering for thin film deposition. The two processes work synergistically to form a stable C-axis preferred-oriented YAlN thin film. This multi-step integrated optimized process avoids the dependence on buffer layers in traditional methods, significantly reducing the cost of thin film preparation while effectively ensuring the C-axis orientation of the film.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for preparing a c-axis preferred oriented YAlN thin film, the method comprising:

[0011] (1) Place the substrate in a vacuum chamber and heat the substrate to the ion implantation temperature;

[0012] (2) Introduce a first gas into the cavity until the gas pressure inside the cavity reaches the first working pressure, and perform ion implantation on the substrate surface;

[0013] (3) Introduce a second working gas into the cavity until the gas pressure inside the cavity reaches the second working pressure, start the sputtering power supply of the target material, and deposit a YAlN thin film by reactive magnetron sputtering on the surface of the substrate after ion implantation treatment.

[0014] The target material in step (3) includes a Y target and an Al target, or the target material includes a YAl alloy target.

[0015] This invention employs plasma ion implantation technology to treat the substrate surface with ions before reactive magnetron sputtering deposition of YAlN thin films, effectively controlling the lattice structure and stress state of the substrate surface, thereby inducing the C-axis preferred orientation growth of YAlN thin films under buffer-free conditions.

[0016] Meanwhile, a dual-target reactive magnetron co-sputtering technique was used to deposit YAlN thin films, using a high-purity Y target and an Al target to co-deposit YAlN alloy thin films, ensuring the crystal quality and reaction uniformity of the films.

[0017] This invention organically combines ion implantation-induced interface modulation with reactive magnetron sputtering thin film deposition, achieving spatial and temporal synergy between the two to form a stable C-axis preferred orientation driving mechanism. This multi-step integrated optimized process avoids the dependence on buffer layers in traditional methods, significantly improving the C-axis orientation and consistency of the thin film.

[0018] The method provided by this invention has a simple process flow, low cost, and strong adaptability to production lines. It is suitable for the preparation of large-area, highly consistent C-axis preferred orientation YAlN thin films and has good prospects for industrial application.

[0019] Preferably, the vacuum degree of the cavity in step (1) is 1.5 × 10⁻⁶. -5 Pa ~ 8×10 -5 Pa.

[0020] Preferably, the ion implantation temperature in step (1) is 100℃~200℃.

[0021] Preferably, in step (2), the first gas includes any one of oxygen, argon, or nitrogen.

[0022] Preferably, in step (2), the flow rate of the first gas is 20 sccm to 40 sccm.

[0023] Preferably, the first working pressure in step (2) is 0.75 Pa to 1.5 Pa.

[0024] Preferably, the substrate in step (1) includes any one of a sapphire substrate, a single-crystal silicon substrate, a silicon carbide substrate, a gallium oxide substrate, or an aluminum nitride single-crystal substrate.

[0025] Preferably, the ion source for the ion implantation process in step (2) includes any one of an anodic ion source, a radio frequency ion source, or a Kaufman ion source.

[0026] Preferably, the power of the ion implantation process in step (2) is 200W~300W.

[0027] Preferably, the ion implantation treatment time in step (2) is 10 min to 30 min.

[0028] Preferably, the depth of ion implantation in step (2) is 10 nm to 20 nm.

[0029] Preferably, in step (3), the second working gas is a combination of argon and nitrogen, and the flow rate ratio of argon to nitrogen is 1:(2~4).

[0030] Preferably, the flow rate of the argon gas is 5 sccm to 10 sccm, and the flow rate of the nitrogen gas is 20 sccm to 25 sccm.

[0031] Preferably, the second working pressure in step (3) is 0.4 Pa to 1 Pa.

[0032] Preferably, the RF power of the sputtering power supply for the Y target in step (3) is 100W~200W.

[0033] Preferably, the radio frequency power of the sputtering power supply for the Al target in step (3) is 400W~500W.

[0034] Preferably, the RF power of the sputtering power supply for the YAl alloy target in step (3) is 100W~500W.

[0035] Preferably, in the YAlN thin film of step (3), the atomic percentage of Y is 4.69%~11.62%, the atomic percentage of Al is 38.06%~45.24%, and the balance is N.

[0036] Preferably, before placing the substrate in the cavity in step (1), the substrate is further cleaned.

[0037] Preferably, the cleaning process includes first ultrasonically cleaning the substrate in acetone for 5 to 10 minutes to remove the surface silicon dioxide layer; then, immersing the substrate in a 3% to 10% hydrofluoric acid solution for 10 to 30 seconds; next, ultrasonically cleaning it sequentially with anhydrous ethanol and deionized water for 5 to 10 minutes; and finally, drying the silicon substrate with a nitrogen gun.

[0038] Preferably, the purity of the Y target and the Al target is each independently 99.99% or higher.

[0039] In a second aspect, the present invention provides a C-axis preferred orientation YAlN thin film, which is prepared by the preparation method described in the first aspect.

[0040] Thirdly, the present invention provides a high-frequency acoustic filter, the high-frequency acoustic filter comprising the C-axis preferred orientation YAlN thin film described in the second aspect.

[0041] In this invention, the terms "first aspect," "second aspect," "third aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) This invention organically combines ion implantation-induced interface modulation with reactive magnetron sputtering thin film deposition. The two work synergistically to form a stable C-axis preferred orientation YAlN thin film deposition. This multi-step integrated optimized process avoids the dependence on buffer layers in traditional methods, significantly reduces the cost of thin film preparation, and effectively ensures the C-axis orientation of the thin film.

[0044] (2) The method provided by the present invention has a simple process flow, low cost and strong production line adaptability. It is suitable for the preparation of large-area, highly consistent C-axis preferred orientation YAlN thin films and has good prospects for industrial application. Attached Figure Description

[0045] Figure 1 These are XRD patterns of the YAlN thin films prepared in Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2. Detailed Implementation

[0046] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. In this invention, "a combination of at least two" means, unless otherwise specified, a quantity greater than or equal to two. For example, "any combination of one or at least two" means one or more of two. It is understood that when referring to "a combination of at least two," it means any suitable combination of multiple items, i.e., a combination of "at least two" items carried out in a manner that does not conflict with and allows for the implementation of the invention.

[0048] In the description of this invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0049] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0050] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0051] In one specific embodiment, the present invention provides a method for preparing a c-axis preferred oriented YAlN thin film, the method comprising:

[0052] (1) Place the substrate in a vacuum chamber and heat the substrate to the ion implantation temperature;

[0053] (2) Introduce a first gas into the cavity until the gas pressure inside the cavity reaches the first working pressure, and perform ion implantation on the substrate surface;

[0054] (3) Introduce a second working gas into the cavity until the gas pressure inside the cavity reaches the second working pressure, start the sputtering power supply of the target material, and deposit a YAlN thin film by reactive magnetron sputtering on the surface of the substrate after ion implantation treatment.

[0055] The target material in step (3) includes a Y target and an Al target, or the target material includes a YAl alloy target.

[0056] This invention employs plasma ion implantation technology to treat the substrate surface with ions before reactive magnetron sputtering deposition of YAlN thin films, effectively controlling the lattice structure and stress state of the substrate surface, thereby inducing the C-axis preferred orientation growth of YAlN thin films under buffer-free conditions.

[0057] Meanwhile, a dual-target reactive magnetron co-sputtering technique was used to deposit YAlN thin films, using a high-purity Y target and an Al target to co-deposit YAlN alloy thin films, ensuring the crystal quality and reaction uniformity of the films.

[0058] This invention organically combines ion implantation-induced interface modulation with reactive magnetron sputtering thin film deposition, achieving spatial and temporal synergy between the two to form a stable C-axis preferred orientation driving mechanism. This multi-step integrated optimized process avoids the dependence on buffer layers in traditional methods, significantly improving the C-axis orientation and consistency of the thin film.

[0059] The method provided by this invention has a simple process flow, low cost, and strong adaptability to production lines. It is suitable for the preparation of large-area, highly consistent C-axis preferred orientation YAlN thin films and has good prospects for industrial application.

[0060] In some embodiments, the vacuum level of the cavity in step (1) is 1.5 × 10⁻⁶. -5 Pa ~ 8×10 -5 Pa, for example, could be 1.5 × 10⁻⁶. -5 Pa, 2×10 -5 Pa, 2.5 × 10 -5 Pa, 3×10 -5 Pa, 3.5 × 10 -5 Pa, 4×10 -5 Pa, 4.5 × 10 -5 Pa, 5×10 -5 Pa, 5.5 × 10 -5 Pa, 6×10 -5 Pa, 6.5 × 10 -5 Pa, 7×10 -5 Pa, 7.5 × 10 -5 Pa or 8×10 -5 Pa.

[0061] In this invention, the substrate temperature affects plasma injection onto the substrate surface and subsequent film growth. During film deposition, if the substrate is not heated, the surface atomic diffusion energy is insufficient, atomic migration is restricted, leading to inadequate nucleation and disordered grain orientation, resulting in low C-axis orientation and crystallinity of the deposited YAlN film. Conversely, when the temperature is too high, the atomic diffusion energy is too large, the surface migration distance is too long, easily causing disordered growth and competition among multi-oriented grains, which also weakens the C-axis preferred orientation. Therefore, a suitable substrate temperature is crucial for obtaining high-quality (002) oriented YAlN films.

[0062] In some embodiments, the ion implantation temperature in step (1) is 100°C to 200°C, for example, it can be 100°C, 120°C, 140°C, 160°C, 180°C or 200°C.

[0063] In some embodiments, the first gas in step (2) includes any one of oxygen, argon, or nitrogen.

[0064] In this invention, the flow rate of the first gas affects the effect of plasma injection into the substrate. If the flow rate of the first gas is too fast, the substrate cannot be etched with a specific orientation during plasma injection. If the flow rate of the first gas is too slow, the vacuum in the chamber is too low, and the ion source cannot work properly and cannot achieve the effect of ion injection.

[0065] In some implementations, the flow rate of the first gas in step (2) is 20 sccm to 40 sccm, for example, it can be 20 sccm, 22 sccm, 24 sccm, 26 sccm, 28 sccm, 30 sccm, 32 sccm, 34 sccm, 36 sccm, 38 sccm or 40 sccm.

[0066] In this invention, a suitable first working pressure can ensure that the ion source can ignite normally, effectively ionize to form plasma, and effectively inject plasma into the substrate.

[0067] In some implementations, the first working pressure in step (2) is 0.75 Pa to 1.5 Pa, for example, it can be 0.75 Pa, 1 Pa, 1.25 Pa or 1.5 Pa.

[0068] In some embodiments, the substrate in step (1) includes any one of a sapphire substrate, a single-crystal silicon substrate, a silicon carbide substrate, a gallium oxide substrate, or an aluminum nitride single-crystal substrate.

[0069] In some embodiments, the ion source for the ion implantation process in step (2) includes any one of an anodic ion source, a radio frequency ion source, or a Kaufman ion source.

[0070] In this invention, the working current of the ion source during ion implantation affects the plasma implantation effect. If the working current is too large, the intensity of plasma bombardment of the substrate is too high, which may cause defects on the substrate surface. If the working current is too small, the implantation effect is not obvious, and the C-axis orientation of the formed YAlN thin film is low.

[0071] In some embodiments, the ion source operating current of the ion implantation process in step (2) is 300mA~500mA, for example, it can be 300mA, 350mA, 400mA, 450mA or 500mA.

[0072] In this invention, if the ion implantation power is too high, the ion implantation on the substrate surface may be too deep; if the power is too low, a high C-axis orientation cannot be formed.

[0073] In some embodiments, the power of the ion implantation process in step (2) is 200W to 300W, for example, 200W, 220W, 240W, 260W, 280W or 300W.

[0074] In some embodiments, the ion implantation treatment time in step (2) is 10 min to 30 min, for example, it can be 10 min, 15 min, 20 min, 25 min or 30 min.

[0075] In this invention, the depth of ion implantation affects whether the thin film can grow effectively along the C-axis and the peak intensity of the (002) crystal plane of the YAlN thin film. If the depth of ion implantation is too large, it may damage the substrate. If the depth of ion implantation is too small, a YAlN thin film with preferred C-axis orientation cannot be obtained.

[0076] In some embodiments, the depth of ion implantation in step (2) is 10nm~20nm, for example, it can be 10nm, 11nm, 12nm, 13nm, 14nm, 15nm, 16nm, 17nm, 18nm, 19nm or 20nm.

[0077] In some embodiments, the second working gas in step (3) is a combination of argon and nitrogen, wherein the flow ratio of argon to nitrogen is 1:(2~4), for example, it can be 1:2, 1:2.5, 1:3, 1:3.5 or 1:4.

[0078] In some embodiments, the flow rate of the argon gas is 5 sccm to 10 sccm, for example, 5 sccm, 6 sccm, 7 sccm, 8 sccm, 9 sccm or 10 sccm, and the flow rate of the nitrogen gas is 20 sccm to 25 sccm, for example, 20 sccm, 21 sccm, 22 sccm, 23 sccm, 24 sccm or 25 sccm.

[0079] In this invention, the second working pressure affects the film deposition rate and the film growth orientation. If the second working pressure is too high, it is not conducive to the film growth along the C-axis orientation. If the second working pressure is too low, the deposition rate will be slowed down, which is not conducive to improving production capacity.

[0080] In some implementations, the second working pressure in step (3) is 0.4 Pa to 1 Pa, for example, it can be 0.4 Pa, 0.5 Pa, 0.6 Pa, 0.7 Pa, 0.8 Pa, 0.9 Pa or 1 Pa.

[0081] In some implementations, the radio frequency power of the sputtering power supply of the Y target in step (3) is 100W~200W, for example, it can be 100W, 120W, 140W, 160W, 180W or 200W.

[0082] In some implementations, the radio frequency power of the sputtering power supply for the Al target in step (3) is 400W~500W, for example, it can be 400W, 420W, 440W, 460W, 480W or 500W.

[0083] In some embodiments, the radio frequency power of the sputtering power supply of the YAl alloy target in step (3) is 100W~500W, for example, it can be 100W, 150W, 200W, 250W, 300W, 350W, 400W, 450W or 500W.

[0084] In some embodiments, the atomic percentage of Y in the YAlN film described in step (3) is 4.69% to 11.62%, for example, it can be 4.69%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11% or 11.62%, and the atomic percentage of Al is 38.06% to 45.24%, for example, it can be 38.06%, 39%, 40%, 41%, 42%, 43%, 44% or 45%, with the balance being N.

[0085] In this invention, the deposition time is no longer specifically limited, and those skilled in the art can adjust the deposition time according to the required YAlN film thickness.

[0086] In some embodiments, the substrate is further cleaned before the substrate in step (1) is placed in the cavity.

[0087] In some embodiments, the cleaning includes first ultrasonically cleaning the substrate in acetone for 5 to 10 minutes to remove the surface silicon dioxide layer; then, immersing the substrate in a 3% to 10% hydrofluoric acid solution for 10 to 30 seconds; next, ultrasonically cleaning it sequentially with anhydrous ethanol and deionized water for 5 to 10 minutes; and finally, drying the silicon substrate with a nitrogen gun.

[0088] In some embodiments, the purity of the Y target and the Al target is each independently greater than 99.99%.

[0089] In another specific embodiment, the present invention provides a C-axis preferred orientation YAlN thin film, which is prepared by the preparation method described in the aforementioned specific embodiment.

[0090] In yet another embodiment, the present invention provides a high-frequency acoustic filter comprising the C-axis preferred-aligned YAlN thin film described in the aforementioned other embodiment.

[0091] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0092] Example 1

[0093] This embodiment provides a method for preparing a C-axis preferred oriented YAlN thin film, including:

[0094] (1) The silicon wafer was ultrasonically cleaned in acetone for 8 minutes to remove the surface silicon dioxide layer. Then, the silicon wafer was immersed in a 5% hydrofluoric acid solution for 30 seconds, and ultrasonically cleaned again with anhydrous ethanol and deionized water for 5 minutes in sequence. After that, the silicon wafer substrate was dried with a nitrogen gun.

[0095] (2) Place the cleaned silicon wafer in the reactive magnetron sputtering chamber and evacuate to 1.5 × 10⁻⁶. -5 The substrate was heated to 100°C; argon gas was introduced at a flow rate of 30 sccm; the gate valve opening was adjusted to stabilize the working pressure in the chamber at 0.8 Pa. The anolyte ion source was set to a working current of 400 mA and a power of 250 W. Argon plasma implantation was performed on the silicon wafer surface for 20 min to a depth of 15 nm.

[0096] (3) Argon gas with a flow rate of 7.5 sccm and nitrogen gas with a flow rate of 22.5 sccm are introduced into the cavity to stabilize the pressure to 0.8 Pa; using a 99.999% high-purity Y target (3 inches) and a 99.999% high-purity Al target (3 inches), the radio frequency power supplies of the Y target and the Al target are turned on respectively. The radio frequency power of the sputtering power supply of the Y target is set to 100W and the radio frequency power of the sputtering power supply of the Al target is set to 500W. A YAlN film with a thickness of 500 nm is deposited by reactive magnetron sputtering on the surface of the silicon wafer after ion implantation treatment. In the YAlN film, the atomic percentage of Y is 4.69%, the mass percentage of Al is 45.24%, and the atomic percentage of N is 50.73%.

[0097] Example 2

[0098] This embodiment provides a method for preparing a C-axis preferred orientation YAlN thin film. Except for step (2), which involves argon plasma implantation on the silicon wafer surface for 10 min and 10 nm, the rest is the same as in Example 1.

[0099] Example 3

[0100] This embodiment provides a method for preparing a C-axis preferred orientation YAlN thin film. Except for step (2), which involves argon plasma implantation on the silicon wafer surface for 30 min and 20 nm, the rest is the same as in Example 1.

[0101] Example 4

[0102] This embodiment provides a method for preparing a C-axis preferred orientation YAlN thin film. Except for the ion implantation time of 15 min and the ion implantation depth of 12 nm in step (2), the rest are the same as in Example 1.

[0103] Example 5

[0104] This embodiment provides a method for preparing a C-axis preferred orientation YAlN thin film. Except for the ion implantation time of 5 min and the ion implantation depth of 5 nm in step (2), the rest are the same as in Example 1.

[0105] Example 6

[0106] This embodiment provides a method for preparing a C-axis preferred orientation YAlN thin film. Except for the substrate heating temperature of 50°C in step (2), the rest is the same as in Example 1.

[0107] Example 7

[0108] This embodiment provides a method for preparing a C-axis preferred orientation YAlN thin film. Except for the substrate heating temperature of 250°C in step (2), the rest is the same as in Example 1.

[0109] Comparative Example 1

[0110] This comparative example provides a method for preparing a C-axis preferred orientation YAlN thin film. Except for step (2), which involves heating the substrate to 100°C without introducing argon gas or performing argon plasma implantation, the rest of the method is the same as in Example 1.

[0111] Comparative Example 2

[0112] This comparative example provides a method for preparing a C-axis preferred orientation YAlN thin film. Except for step (2), which does not heat the substrate and keeps its temperature at room temperature (25°C), the rest is the same as in Example 1.

[0113] Performance testing:

[0114] Under the conditions of Cu target, ceramic X-ray tube, operating at 40 kV × 40 mA, step size of 0.02°, and step time of 0.35 s, XRD tests were performed on the YAlN thin films prepared in all the above examples and comparative examples. The characteristic peaks corresponding to the C-axis preferred orientation of the (002) crystal plane in the YAlN thin films are shown in Table 1. The XRD patterns of the YAlN thin films prepared in Examples 1, 2, 3, Comparative Examples 1, and 2 are shown in Table 2. Figure 1 As shown.

[0115] Table 1

[0116]

[0117] Based on the test results in Table 1, this invention organically combines ion implantation-induced interface modulation with reactive magnetron sputtering thin film deposition, achieving spatial and temporal synergy to form a stable C-axis preferred orientation driving mechanism. This multi-step integrated optimized process avoids the dependence on buffer layers in traditional methods, significantly improving the C-axis orientation and consistency of the thin film.

[0118] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a c-axis preferred oriented YAlN thin film, characterized in that, The preparation method includes: (1) Place the substrate in a vacuum chamber and heat the substrate to the ion implantation temperature; (2) Introduce a first gas into the cavity until the gas pressure inside the cavity reaches the first working pressure, and perform ion implantation on the substrate surface; (3) Introduce a second working gas into the cavity until the gas pressure inside the cavity reaches the second working pressure, start the sputtering power supply of the target material, and deposit a YAlN thin film by reactive magnetron sputtering on the surface of the substrate after ion implantation treatment. The target material in step (3) includes a Y target and an Al target, or the target material includes a YAl alloy target; The ion implantation temperature in step (1) is 100℃~200℃; The ion implantation depth in step (2) is 10 nm to 20 nm.

2. The preparation method according to claim 1, characterized in that, The vacuum level of the cavity in step (1) is 1.5 × 10⁻⁶. - 5 Pa ~ 8×10 -5 Pa.

3. The preparation method according to claim 1, characterized in that, Step (2) The first gas includes any one of oxygen, argon or nitrogen; And / or, in step (2), the first working pressure is 0.75 Pa to 1.5 Pa.

4. The preparation method according to claim 1, characterized in that, The substrate in step (1) includes any one of sapphire substrate, single crystal silicon substrate, silicon carbide substrate, gallium oxide substrate or aluminum nitride single crystal substrate.

5. The preparation method according to claim 1, characterized in that, The ion source for the ion implantation process in step (2) includes any one of an anodic ion source, a radio frequency ion source, or a Kaufman ion source.

6. The preparation method according to claim 1, characterized in that, Step (3) The second working gas is a combination of argon and nitrogen, and the flow rate ratio of argon to nitrogen is 1:(2~4); And / or, in step (3), the second working pressure is 0.4 Pa to 1 Pa.

7. The preparation method according to claim 1, characterized in that, The RF power of the sputtering power supply for the Y target in step (3) is 100W~200W, and the RF power of the sputtering power supply for the Al target is 400W~500W. And / or, the RF power of the sputtering power supply for the YAl alloy target in step (3) is 100W~500W; And / or, in the YAlN thin film described in step (3), the atomic percentage of Y is 4.69%~11.62%, the atomic percentage of Al is 38.06%~45.24%, and the balance is N.

8. The preparation method according to claim 1, characterized in that, Before placing the substrate in the cavity in step (1), the substrate is also cleaned.

9. A c-axis preferred oriented YAlN thin film, characterized in that, The C-axis preferred orientation YAlN thin film is prepared by the preparation method described in any one of claims 1 to 8.

10. A high-frequency acoustic filter, characterized in that, The high-frequency acoustic filter includes the C-axis preferred orientation YAlN thin film as described in claim 9.

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