Stacked structure

Abstract

Provided is a stacked structure in which it is possible to form, on an Si substrate, a dielectric film that comprises LiNbO3 or LiTaO3 and that is oriented in a plane different from the (0001) plane.　The laminated structure (10) has a substrate (11), a buffer film (12) formed on the substrate (11), and a dielectric film (15) formed on the buffer film (12). The substrate is composed of an Si substrate or an SOI substrate. The buffer film (12) contains a first metal oxide represented by compositional formula (1), x satisfies 0 ≤ x < 1 or x = 1, and the dielectric film (15) comprises only one dielectric layer (15a) or comprises only two to four dielectric layers stacked on each other. The one dielectric layer (15a) or each of the two to four dielectric layers has an ilmenite structure and contains a second metal oxide comprising LiNbO3 or LiTaO3 oriented in a fixed direction. Formula 1: (Hf1 - xZrx)O2

Description

Laminated structure

[0001] This invention relates to a laminated structure.

[0002] In the communications field, the demand for frequency filters is increasing, and among them, the demand for surface acoustic wave (SAW) filters is on the rise. LiNbO is used as the piezoelectric material for SAW filters. ３ Or LiTaO ３ Metal oxides having an ilmenite-type structure are used. In addition, multilayer structures obtained by epitaxially growing metal oxides having an ilmenite-type structure on a Si substrate, and electronic devices equipped with such multilayer structures are known.

[0003] Japanese Patent Publication No. 2013-173647 (Patent Document 1) describes a dielectric multilayer thin film in which zirconium oxide (ZrO) is applied to the surface of a single crystal Si(111) substrate. ２ A technique is disclosed in which at least one epitaxially grown underlayer film mainly composed of ) is formed, and an epitaxially grown ilmenite structure film made of an ilmenite structure dielectric material is formed on the underlayer film.

[0004] International Publication No. 2023 / 210309 (Patent Document 2) describes a film structure comprising a substrate, a buffer film formed on the substrate, and a piezoelectric film formed on the buffer film, wherein the substrate is a Si(100) substrate, or an SOI substrate comprising a substrate made of a Si substrate, an insulating layer on the substrate, and an SOI layer made of a Si(100) film on the insulating layer, and the buffer film is ZrO ２ The piezoelectric film contains c-axis oriented LiNbO ３ Or LiTaO ３ The technology including this has been disclosed.

[0005] Japanese Patent Publication No. 2022-159810 (Patent Document 3) describes a piezoelectric device comprising a substrate, a lower electrode, a buffer layer disposed on the lower electrode, and LiNbO disposed on the buffer layer with its crystal orientation oriented in the (012) plane. ３ Or LiTaO ３a piezoelectric film made of, wherein a technique is disclosed in which the buffer layer orients the crystal orientation of the piezoelectric film in the (012) plane direction.

[0006] Japanese Patent Application Laid-Open No. 2013-173647 International Publication No. WO 2023 / 210309 Japanese Patent Application Laid-Open No. 2022-159810

[0007] J. Kushibiki et. al., “Accurate measurements of the acoustical physical constants of LiNbO3 and LiTaO3single crystals”, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, Vol. 46, No. 5, (1999) p.1315-1323

[0008] In the technique described in Patent Document 1, the dielectric laminated thin film has an ilmenite-type structure formed on a Si(111) substrate and is (0001)-oriented LiNbO ３ or LiTaO ３ It is described that the film has the above-mentioned film. Further, in the technique described in Patent Document 2, the film structure includes a Si(100) substrate and LiNbO having an ilmenite-type structure formed on the Si(100) substrate and being c-axis oriented ３ or LiTaO ３ It is described that the film structure has the above.

[0009] On the other hand, from the techniques described in Patent Document 3 and Non-Patent Document 1, LiNbO ３ and the like, the (01-12) plane is expected to exhibit a high electromechanical coupling coefficient. However, LiNbO ３ or LiTaO ３ It has been difficult to epitaxially grow a dielectric film made of the above, which is (01-12)-oriented or oriented in a plane different from the (0001) plane, and has excellent crystallinity on a Si substrate.

[0010] The present invention provides LiNbO ３ or LiTaO ３The objective is to provide a laminated structure that can be easily epitaxially grown in a (01-12) oriented state or in a state oriented to a plane different from the (0001) plane, and that can form a dielectric film with excellent crystallinity on a Si substrate.

[0011] As a result of diligent research, the present inventors have found that the above problems can be solved by the following configuration: [1] A laminated structure having a substrate, a buffer film formed on the substrate, and a dielectric film formed on the buffer film, wherein the substrate is a Si substrate, or an SOI substrate comprising a substrate made of a Si substrate, an insulating layer on the substrate, and an SOI layer made of a Si film on the insulating layer, and the buffer film contains a first metal oxide represented by the following composition formula (1), (Hf １－ｘ Zr ｘ ) O ２ ... (1) The x satisfies 0 ≤ x < 1 or x = 1, the dielectric film consists of only one first dielectric layer or only two to four second dielectric layers stacked on top of each other, each of the one first dielectric layer or the two to four second dielectric layers has an ilmenite-type structure and is oriented in a certain direction. ３ Or LiTaO ３ A laminated structure comprising a second metal oxide. [2] In the laminated structure described in [1], the substrate comprises a main surface, the substrate comprises a Si(111) substrate comprising the main surface comprising a Si(111) plane, or an SOI substrate comprising a substrate, an insulating layer on the substrate, and an SOI layer comprising a Si(111) film on the insulating layer and comprising the main surface comprising a Si(111) plane, the buffer film is formed on the main surface and comprises the first metal oxide oriented (111) in pseudocubic crystal representation, each of the one first dielectric layer or the two to four second dielectric layers has an ilmenite-type structure and is (01-12) oriented LiNbO ３ Or LiTaO ３A laminated structure comprising the second metal oxide comprising [3] [2], wherein the first metal oxide is epitaxially grown on the main surface, and the second metal oxide is epitaxially grown on the buffer film. ３ Or LiTaO ３ A laminated structure comprising [4] [3], wherein each of the first dielectric layer of the first layer or the second to fourth dielectric layers is oriented such that the (0001) plane of the second metal oxide is inclined by a first angle with respect to the main plane, and includes a first domain, a second domain, a third domain, a fourth domain, a fifth domain and a sixth domain in which the

[0001] axes of the second metal oxide are oriented in different directions from each other, and LiNbO contained in the second metal oxide in the second domain ３ Or LiTaO ３ The

[0001] direction is such that, when viewed from the direction normal to the main surface, the LiNbO contained in the second metal oxide in the first domain ３ Or LiTaO ３ This is a direction rotated 60° counterclockwise from the

[0001] direction, and LiNbO contained in the second metal oxide in the third domain ３ Or LiTaO ３ The

[0001] direction is such that, when viewed from the direction normal to the main surface, the LiNbO contained in the second metal oxide in the first domain ３ Or LiTaO ３ This is a direction rotated 120° counterclockwise from the

[0001] direction, and LiNbO contained in the second metal oxide in the fourth domain ３ Or LiTaO ３ The

[0001] direction is such that, when viewed from the normal direction of the main surface, the LiNbO contained in the second metal oxide in the first domain ３ Or LiTaO ３ This is a direction rotated 180° counterclockwise from the

[0001] direction, and LiNbO contained in the second metal oxide in the fifth domain ３ Or LiTaO ３The

[0001] direction is such that, when viewed from the normal direction of the main surface, the LiNbO contained in the second metal oxide in the first domain ３ Or LiTaO ３ This is a direction rotated 240° counterclockwise from the

[0001] direction, and LiNbO contained in the second metal oxide in the sixth domain ３ Or LiTaO ３ The

[0001] direction is such that, when viewed from the normal direction of the main surface, the LiNbO contained in the second metal oxide in the first domain ３ Or LiTaO ３ A laminated structure, the direction being rotated 300° counterclockwise from the

[0001] direction. [5] The laminated structure according to [3] or [4], further comprising a first conductive film formed on the buffer film, wherein the first conductive film is epitaxially grown on the buffer film, has a cubic crystal structure, and contains a (111) oriented platinum group element, and the second metal oxide is LiNbO, epitaxially grown on the first conductive film ３ Or LiTaO ３ A laminated structure comprising [6] [5], further comprising a second conductive film formed on the first conductive film, wherein the second conductive film contains strontium ruthenate epitaxially grown on the first conductive film and oriented (111) in pseudocubic crystal representation, and the second metal oxide is LiNbO epitaxially grown on the second conductive film. ３ Or LiTaO ３ A laminated structure comprising: [7] In the laminated structure described in [1], the substrate comprises a main surface, the substrate comprises a Si(100) substrate comprising the main surface comprising a Si(100) plane, or an SOI substrate comprising the substrate, the insulating layer on the substrate, and the SOI layer comprising a Si(100) film on the insulating layer and comprising the main surface comprising a Si(100) plane, the buffer film is formed on the main surface and comprises the first metal oxide oriented to (100) in pseudocubic crystal representation, each of the one first dielectric layer or the two to four second dielectric layers has an ilmenite-type structure and is (01-12) oriented LiNbO３ Or LiTaO ３ A laminated structure comprising the second metal oxide comprising [8] [7], wherein the first metal oxide is epitaxially grown on the main surface, and the second metal oxide is epitaxially grown on the buffer film. ３ Or LiTaO ３ A laminated structure comprising [9] [8], wherein each of the first dielectric layer of the first layer or the second to fourth dielectric layers of the second layer is oriented such that the (0001) plane of the second metal oxide is inclined by a first angle with respect to the main plane, and includes a first domain, a second domain, a third domain and a fourth domain in which the

[0001] axes of the second metal oxide are oriented in different directions from each other, wherein the second domain contains LiNbO ３ Or LiTaO ３ The

[0001] direction is such that, when viewed from the normal direction of the main surface, the LiNbO contained in the second metal oxide in the first domain ３ Or LiTaO ３ This is a direction rotated 90° counterclockwise from the

[0001] direction, and LiNbO contained in the second metal oxide in the third domain ３ Or LiTaO ３ The

[0001] direction is such that, when viewed from the normal direction of the main surface, the LiNbO contained in the second metal oxide in the first domain ３ Or LiTaO ３ This is a direction rotated 180° counterclockwise from the

[0001] direction, and LiNbO contained in the second metal oxide in the fourth domain ３ Or LiTaO ３ The

[0001] direction is such that, when viewed from the normal direction of the main surface, the LiNbO contained in the second metal oxide in the first domain ３ Or LiTaO ３A laminated structure, the direction being rotated 270° counterclockwise from the

[0001] direction. In the laminated structure according to

[10] [8] or [9], further comprising a first conductive film formed on the buffer film, wherein the first conductive film is epitaxially grown on the buffer film, has a cubic crystal structure, and contains a (100) oriented platinum group element, and the second metal oxide is LiNbO, epitaxially grown on the first conductive film. ３ Or LiTaO ３ A laminated structure comprising

[11]

[10] , further comprising a second conductive film formed on the first conductive film, wherein the second conductive film contains strontium ruthenate epitaxially grown on the first conductive film and oriented (100) in pseudocubic crystal representation, and the second metal oxide is LiNbO epitaxially grown on the second conductive film. ３ Or LiTaO ３ A layered structure.

[0012] The laminated structure of the present invention is LiNbO ３ Or LiTaO ３ This material allows for easy epitaxial growth in a (01-12) oriented state or in a state oriented to a plane different from the (0001) plane, and enables the formation of a dielectric film with excellent crystallinity on a Si substrate.

[0013] This is a cross-sectional view showing an example of a laminated structure according to the first embodiment. This is a cross-sectional view showing another example of a laminated structure according to the first embodiment. LiNbO contained in the second metal oxide in the laminated structure according to the first embodiment. ３ This is a schematic plan view showing the orientation state of the crystal lattice. LiNbO contained in the second metal oxide in the laminated structure of the first embodiment. ３ This is a schematic side view showing the orientation state of the crystal lattice. LiNbO has an ilmenite-type structure and is (01-12) oriented. ３ This is a diagram showing the crystal structure. This is a cross-sectional view showing an example of a laminated structure of the second embodiment. LiNbO contained in the metal nitride in the laminated structure of the second embodiment ３This is a schematic plan view showing the orientation state of the crystal lattice. LiNbO contained in the metal nitride in the laminated structure of the second embodiment ３ This is a schematic side view showing the orientation state of the crystal lattice. This is a graph showing the diffraction pattern of the stacked structure of Example 1. This is a graph showing the diffraction pattern of the stacked structure of Example 2.

[0014] The embodiments of the present invention will be described below with reference to the drawings.

[0015] <First Embodiment> The laminated structure according to the first embodiment will now be described. Figure 1 is a cross-sectional view showing an example of the laminated structure according to the first embodiment. Figure 2 is a cross-sectional view showing another example of the laminated structure according to the first embodiment. Figure 1 shows a case where the dielectric film 15 consists of only one dielectric layer 15a, and Figure 2 shows a case where the dielectric film 15 consists of only two dielectric layers 15a stacked on top of each other.

[0016] The laminated structure 10 shown in Figures 1 and 2 comprises a substrate 11 including a main surface 11p, a buffer film 12 formed on the main surface 11p, a conductive film (first conductive film) 13 formed on the buffer film 12, a conductive film (second conductive film) 14 formed on the conductive film 13, and a dielectric film 15 formed on the conductive film 14.

[0017] In the example shown in Figure 1, the substrate 11 is made of a silicon (Si) (111) substrate including a main surface 11p made of a Si (111) surface. In the example shown in Figure 2, the substrate 11 is made of an SOI (Silicon On Insulator) substrate including a base body 11a made of a Si substrate, an insulating layer 11b on the base body 11a, and an SOI (Silicon On Insulator) layer 11c on the insulating layer 11b that is made of a Si (111) film and includes a main surface 11p made of a Si (111) surface.

[0018] The buffer film 12 is epitaxially grown on the main surface 11p, is (111) oriented in pseudocubic crystal representation, and contains a first metal oxide represented by the following compositional formula (2). (Hf １－ｘ Zr ｘ ) O ２... (2) In the above empirical formula (2), x satisfies either 0 ≤ x < 1 or x = 1. Note that the above empirical formula (2) is the same empirical formula as the above empirical formula (1).

[0019] In this specification, when the first metal oxide is described as being (111) oriented in pseudocubic crystal representation, it means that the first metal oxide has a cubic crystal structure at room temperature and is (111) oriented, or that even if it has a tetragonal or monoclinic crystal structure at room temperature, it undergoes a phase transition at high temperatures to have a cubic crystal structure and is (111) oriented. Furthermore, in the following, among the first metal oxides represented by the above compositional formula (2), when x = 0, HfO ２ And when x = 1, ZrO ２ However, the case where 0 < x < 1 is satisfied is sometimes referred to as HZO.

[0020] Furthermore, in this specification, if a film is said to be epitaxially grown, it means that the film is oriented in any of the three mutually orthogonal directions, that is, oriented in three dimensions.

[0021] The conductive film 13 is epitaxially grown on the buffer film 12, has a cubic crystal structure, and contains platinum group elements such as (111)-oriented platinum (Pt). The conductive film 13 corresponds to the first conductive film.

[0022] The conductive film 14 is epitaxially grown on the conductive film 13 and is (111) oriented in a pseudocubic crystal structure as strontium ruthenate (SrRuO ３ ) includes. The conductive film 14 corresponds to the second conductive film.

[0023] The dielectric film 15 consists of only one dielectric layer (first dielectric layer) 15a, or only two to four dielectric layers (second dielectric layer) 15a stacked on top of each other. Furthermore, each of the one first dielectric layer or the two to four second dielectric layers is epitaxially grown on the conductive film 14, has an ilmenite-type structure, and is (01-12) oriented LiNbO ３ Or LiTaO ３comprises a second metal oxide. When the dielectric film 15 is formed, for example, in a case where film formation is continuously performed in the same film formation chamber from the start of film formation to the end of film formation, the dielectric film 15 consists of only one dielectric layer 15a grown continuously from the lower surface to the upper surface. On the other hand, when forming the dielectric film 15, for example, when film formation is resumed under different film formation conditions or compositions after stopping film formation in the middle, or when film formation is stopped in the middle, moved to another film formation chamber, and then resumed under the same or different film formation conditions or compositions, the dielectric film 15 consists of only two dielectric layers 15a. Alternatively, for example, by repeatedly stopping film formation in the middle and then resuming film formation under different film formation conditions or compositions, the dielectric film 15 consists of only three or four dielectric layers 15a. Here, as an example where the dielectric film 15 consists of only two dielectric layers 15a, there can be mentioned a case where a first dielectric layer 15a of about 100 nm is formed as a base film, and then a second dielectric layer 15a of about 1 µm is formed as the main body film of the dielectric film 15 on the base film. Note that the statement that the dielectric film 15 consists of only one dielectric layer 15a means that the number of dielectric layers 15a included in the dielectric film 15 is only one, and the statement that the dielectric film 15 consists of only n (2≦n≦4) mutually laminated dielectric layers 15a means that the number of dielectric layers 15a included in the dielectric film 15 is only n.

[0024] In the technology described in Patent Document 1 above, the dielectric laminated thin film has an ilmenite-type structure formed on a Si(111) substrate and includes (0001)-oriented LiNbO ３ or LiTaO ３ It is described that the film has the above-mentioned film. In addition, in the technology described in Patent Document 2 above, the film structure includes a Si(100) substrate and c-axis-oriented LiNbO having an ilmenite-type structure formed on the Si(100) substrate ３ or LiTaO ３ It is described that the structure has the above-mentioned component.

[0025] On the other hand, in the technology described in Patent Document 3 above, LiNbO ３ a 36° Y-cut LiNbO obtained by 36° rotation Y-cutting a bulk body ３It is described that when a single crystal plate is used, the maximum electromechanical coupling coefficient of quasi-longitudinal waves is about 50%. In addition, in the technology described in the above Non-Patent Document 1, the (01-12) plane is 32.76° Y-cut LiNbO ３ It is described that it corresponds to a single crystal plate and has a high longitudinal wave velocity. 32.76° Y-cut LiNbO ３ Since the single crystal plate is close to 36° Y-cut LiNbO ３ single crystal plate, it is expected to exhibit a high electromechanical coupling coefficient. In addition, LiNbO ３ Not only for single crystal plates, but also for LiTaO ３ the same tendency is expected for single crystal plates.

[0026] However, it has been difficult to epitaxially grow a dielectric film made of LiNbO ３ or LiTaO ３ in a (01-12) oriented state on a Si substrate. That is, it has been difficult to form a dielectric film excellent in crystallinity, which is made of LiNbO ３ or LiTaO ３ , can be easily epitaxially grown in a (01-12) oriented state or in a state oriented to a plane different from the (0001) plane, on a Si substrate.

[0027] On the other hand, in the laminated structure of the present embodiment, ZrO ２ , HZO or HfO ２ formed on a substrate 11 made of a Si substrate or an SOI substrate, via a buffer film 12 made of , a conductor film 13 containing a platinum group element, and a conductor film 14 containing SrRuO ３ , LiNbO ３ or LiTaO ３ dielectric film 15 made of is formed.

[0028] In such a laminated structure of the present embodiment, (01-12) oriented LiNbO is formed on a single crystal Si (111) substrate. ３ or LiTaO ３ dielectric film 15 made of can be epitaxially grown. In addition, as described in the second embodiment described later, (01-12) oriented LiNbO is formed on a single crystal Si (100) substrate. ３ or LiTaO ３A dielectric film 15 can be epitaxially grown on a single crystal Si substrate. ３ Or LiTaO ３ The dielectric film 15 can be epitaxially grown in a state where it is oriented to a plane different from the (0001) plane.

[0029] Therefore, according to the laminated structure of this embodiment, LiNbO ３ Or LiTaO ３ This material allows for easy epitaxial growth in a (01-12) oriented state or in a state oriented to a plane different from the (0001) plane, and enables the formation of a dielectric film with excellent crystallinity on a Si substrate.

[0030] According to this embodiment, HfO is placed on a substrate 11 made of a Si substrate or an SOI substrate. ２ , HZO or ZrO ２ The conductive film 13, conductive film 14, and dielectric film 15 can be easily epitaxially grown via a buffer film 12 containing a first metal oxide. For example, the main component of the buffer film 12 is HfO ２ , HZO or ZrO ２ It is thought that the dynamic lattice matching effect due to the twinning martensitic transformation exhibited by the first metal oxide acts as the driving force, propulsion, and propulsion during the epitaxial growth of the conductive film 13, conductive film 14, and dielectric film 15, according to the crystal growth mechanism. However, the theory is not necessarily bound by this.

[0031] Furthermore, as mentioned above, the dielectric film 15 consists of only one dielectric layer 15a when it is deposited continuously in the same deposition chamber from the start to the end of deposition, or it consists of only two to four layers of dielectric layers 15a stacked on top of each other when deposition is stopped midway and then restarted under different deposition conditions or composition. For a dielectric film 15 consisting of only one or two to four layers of dielectric layers 15a, instead of deposition methods that deposit the dielectric film 15 under atmospheric pressure, such as coating methods, a deposition method that deposits the dielectric film 15 under a vacuum atmosphere in a deposition chamber equipped with a vacuum evacuation system, such as sputtering, can be used. With this sputtering method, the dielectric film 15 can be continuously deposited on the substrate at a high deposition rate. Therefore, even when the film thickness is thick, the deposition time can be shortened, making it easy to create a thick dielectric film 15.

[0032] In the laminated structure of this embodiment, the substrate 11 is a Si(111) substrate including a main surface made of Si(111) planes, or an SOI substrate including a substrate made of a Si substrate, an insulating layer on the substrate, and an SOI layer made of a Si(111) film on the insulating layer and including a main surface made of Si(111) planes, the buffer film 12 contains a first metal oxide oriented (111) in pseudocubic crystal representation, the conductive film 13 has a cubic crystal structure and contains a platinum group element such as Pt oriented (111), and the conductive film 14 contains SrRuO oriented (111) in pseudocubic crystal representation ３ The dielectric film 15 consists of either a single dielectric layer 15a or two to four dielectric layers 15a stacked on top of each other, and each of the single dielectric layer 15a or the two to four dielectric layers 15a is epitaxially grown on the conductive film 14 and has an ilmenite-type structure and is (01-12) oriented LiNbO ３ Or LiTaO ３ It contains a secondary metal oxide.

[0033] However, the dielectric film 15 consists of only one dielectric layer 15a, or only two to four dielectric layers 15a stacked on top of each other, and each of the one dielectric layer 15a or the two to four dielectric layers 15a is oriented in a certain direction with respect to the main surface LiNbO３ Or LiTaO ３ It is sufficient that the substrate contains a second metal oxide, and the substrate 11 does not have to be a Si(111) substrate containing a main surface made of Si(111) planes, or an SOI substrate containing an SOI layer containing a main surface made of Si(111) planes.

[0034] Therefore, as shown in the second embodiment described later, the substrate 11 may consist of a Si(100) substrate including a main surface made of Si(100) planes, or an SOI substrate including a substrate made of a Si substrate, an insulating layer on the substrate, and an SOI layer made of a Si(100) film on the insulating layer and including a main surface made of Si(100) planes. Even in such cases, a dielectric film having an ilmenite-type structure or other various single-crystal high-quality dielectric films can be oriented in a certain direction on the Si substrate, so LiNbO ３ Or LiTaO ３ This material allows for easy epitaxial growth in a (01-12) oriented state or in a state oriented to a plane different from the (0001) plane, and enables the formation of a dielectric film with excellent crystallinity on a Si substrate.

[0035] Furthermore, in the laminated structure of this embodiment, the buffer film 12 contains a first metal oxide epitaxially grown on the main surface 11p of the substrate 11, the conductive film 13 contains a platinum group element such as Pt epitaxially grown on the buffer film 12, and the conductive film 14 contains SrRuO epitaxially grown on the conductive film 13. ３ The dielectric film 15 includes LiNbO, which is epitaxially grown on the conductive film 14. ３ Or LiTaO ３ It contains a secondary metal oxide.

[0036] However, the buffer film 12 does not necessarily have to contain a first metal oxide epitaxially grown on the main surface 11p of the substrate 11, the conductive film 13 does not necessarily have to contain a platinum group element such as Pt epitaxially grown on the buffer film 12, and the conductive film 14 may contain SrRuO epitaxially grown on the conductive film 13. ３It does not have to include. Even in such cases, for example, by oriented the buffer film 12, the conductive film 13 and the conductive film 14 in a single direction, a dielectric film having an ilmenite-type structure and other various single-crystal high-quality dielectric films can be oriented in a certain direction on the Si substrate, so LiNbO ３ Or LiTaO ３ This material allows for easy epitaxial growth in a (01-12) oriented state or in a state oriented to a plane different from the (0001) plane, and enables the formation of a dielectric film with excellent crystallinity on a Si substrate.

[0037] Furthermore, the laminated structure of this embodiment has a buffer film 12, a conductive film 13, a conductive film 14, and a dielectric film 15, and the dielectric film 15 is formed on the buffer film 12 via the conductive film 13 and the conductive film 14.

[0038] However, the laminated structure of this embodiment does not necessarily have conductive films 13 and 14, and the dielectric film 15 may be formed directly on the buffer film 12. Even in such a case, for example, the buffer film 12 may contain a first metal oxide epitaxially grown on the main surface 11p of the substrate 11, thereby providing LiNbO ３ Or LiTaO ３ The material is such that it can be easily epitaxially grown in a (01-12) oriented state or in a state oriented to a plane different from the (0001) plane, and a dielectric film with excellent crystallinity can be formed on the buffer film 12.

[0039] Figure 3 shows the LiNbO contained in the second metal oxide in the laminated structure according to the first embodiment. ３ This is a schematic plan view showing the orientation state of the crystal lattice. Figure 4 shows the LiNbO contained in the second metal oxide in the stacked structure according to the first embodiment. ３ This is a schematic side view showing the orientation state of the crystal lattice. In Figures 3 and 4, for ease of understanding, LiNbO is represented by a hexagonal crystal lattice instead of a trigonal one. ３ The crystal lattice is further shown as a quadrangular prism. Also, for ease of understanding, the (0001) plane is hatched in Figure 3, and the second domain DM2 and the fourth domain DM4 are omitted from the illustration in Figure 4.

[0040] As shown in Figures 3 and 4, it is preferable that each of the single dielectric layer 15a or the two to four dielectric layers 15a is oriented such that the (0001) plane of the second metal oxide is tilted by a first angle θ11 with respect to the main plane, and that it contains a first domain DM1, a second domain DM2, a third domain DM3, a fourth domain DM4, a fifth domain DM5, and a sixth domain DM6 in which the

[0001] axes of the second metal oxide are oriented in different directions. ３ When this is the case, the first angle θ11 can be set to, for example, 52.24° to 70°, and for example, 57.24°. On the other hand, the second metal oxide is LiTaO ３ When this occurs, the first angle θ11 can be, for example, 52.02° to 75°, or for example, 57.02°.

[0041] Here, in the second domain DM2, LiNbO is included in the second metal oxide. ３ Or LiTaO ３ The

[0001] direction is such that, when viewed from the normal direction of the main surface 11p (around the normal direction of the main surface 11p), LiNbO contained in the second metal oxide in the first domain DM1 ３ Or LiTaO ３ This is the direction rotated 60° counterclockwise from the

[0001] direction. Also, in the third domain DM3, LiNbO contained in the second metal oxide ３ Or LiTaO ３ The

[0001] direction is such that, when viewed from the normal direction of the main surface 11p (around the normal direction of the main surface 11p), LiNbO contained in the second metal oxide in the first domain DM1 ３ Or LiTaO ３ This is the direction rotated 120° counterclockwise from the

[0001] direction. Also, in the fourth domain DM4, LiNbO contained in the second metal oxide ３ Or LiTaO ３ The

[0001] direction is such that, when viewed from the normal direction of the main surface 11p (around the normal direction of the main surface 11p), LiNbO contained in the second metal oxide in the first domain DM1 ３ Or LiTaO ３This is the direction rotated 180° counterclockwise from the

[0001] direction. Also, in the fifth domain DM5, LiNbO contained in the second metal oxide ３ Or LiTaO ３ The

[0001] direction is such that, when viewed from the normal direction of the main surface 11p (around the normal direction of the main surface 11p), LiNbO contained in the second metal oxide in the first domain DM1 ３ Or LiTaO ３ This is the direction rotated 240° counterclockwise from the

[0001] direction. Also, in the sixth domain DM6, LiNbO contained in the second metal oxide ３ Or LiTaO ３ The

[0001] direction, when viewed from the direction normal to the main surface (around the direction normal to the main surface 11p), is the LiNbO contained in the second metal oxide in the first domain DM1. ３ Or LiTaO ３ This is the direction rotated 300° counterclockwise from the

[0001] direction.

[0042] In such cases, LiNbO contained in the second metal oxide in the dielectric film 15 ３ Or LiTaO ３ Since it is oriented (01-12), LiNbO ３ Or LiTaO ３ The inclination angle of the (0001) surface relative to the main surface 11p can be easily controlled to be a constant angle. In addition, the (01-12) oriented LiNbO ３ The dielectric film 15 is made of 36° Y-cut LiNbO ３ It possesses an electromechanical coupling coefficient as high as that of a single crystal plate, as well as a high longitudinal wave velocity. Therefore, it is possible to realize electronic devices such as SAW filters with high electromechanical coupling coefficients and excellent filter characteristics.

[0043] Figure 5 shows LiNbO having an ilmenite-type structure and (01-12) oriented. ３ This figure shows the crystal structure. In Figure 5, for ease of understanding, only some of the Nb atoms contained in the crystal lattice are shown, and the (01-12) plane is represented by plane PL.

[0044] <Second Embodiment> Next, a laminated structure according to the second embodiment will be described. The laminated structure according to the second embodiment differs from the laminated structure according to the first embodiment in that the main surface 11p of the substrate 11 is made of a Si(100) surface. Furthermore, in the laminated structure according to the second embodiment, parts other than the orientation direction of the substrate 11 and each layer can be the same as the parts of the laminated structure according to the second embodiment, and their description will be omitted.

[0045] Figure 6 is a cross-sectional view showing an example of a laminated structure according to the second embodiment. Figure 6 shows the case where the dielectric film 15 consists of only one dielectric layer 15a.

[0046] As shown in Figure 6, the substrate 11 in the laminated structure 10a of the second embodiment differs from the laminated structure of the first embodiment in that it is made of a Si(100) substrate including a main surface 11p made of a Si(100) surface. Alternatively, as shown in Figure 2, the substrate 11 may be made of an SOI substrate including a base body 11a made of a Si substrate, an insulating layer 11b on the base body 11a, and an SOI layer 11c on the insulating layer 11b that is made of a Si(100) film and includes a main surface 11p made of a Si(100) surface.

[0047] Unlike the laminated structure of the first embodiment, the buffer film 12 is epitaxially grown on the main surface 11p, oriented (100) in pseudocubic crystal representation, and contains the first metal oxide represented by the above composition formula (2). In addition, in the above composition formula (2), x satisfies 0 ≤ x < 1 or x = 1.

[0048] Unlike the laminated structure according to the first embodiment, the conductive film 13 is epitaxially grown on the buffer film 12, has a cubic crystal structure, and contains platinum group elements such as (100)-oriented platinum (Pt). The conductive film 13 corresponds to the first conductive film, similar to the laminated structure according to the first embodiment.

[0049] Unlike the laminated structure according to the first embodiment, the conductive film 14 is epitaxially grown on the conductive film 13 and is (100) oriented in a pseudocubic crystal structure, and is composed of strontium ruthenate (SrRuO ３ ) is included. Note that the conductive film 14 corresponds to the second conductive film, similar to the laminated structure according to the first embodiment.

[0050] The dielectric film 15 consists of only one dielectric layer (first dielectric layer) 15a, or only two to four dielectric layers (second dielectric layer) 15a stacked on top of each other. Furthermore, each of the one first dielectric layer or the two to four second dielectric layers is epitaxially grown on the conductive film 14, has an ilmenite-type structure, and is (01-12) oriented LiNbO ３ Or LiTaO ３ It contains a secondary metal oxide.

[0051] In the laminated structure according to the second embodiment, similar to the laminated structure according to the first embodiment, (01-12) oriented LiNbO is placed on a single crystal Si(100) substrate. ３ Or LiTaO ３ A dielectric film 15 can be epitaxially grown on a single crystal Si substrate. ３ Or LiTaO ３ The dielectric film 15 can be epitaxially grown in a state where it is oriented to a plane different from the (0001) plane.

[0052] Therefore, according to the laminated structure of the second embodiment, similar to the laminated structure of the first embodiment, LiNbO is more efficient than the technologies described in Patent Documents 1 to 3. ３ Or LiTaO ３ This material allows for easy epitaxial growth in a (01-12) oriented state or in a state oriented to a plane different from the (0001) plane, and enables the formation of a dielectric film with excellent crystallinity on a Si substrate.

[0053] In the laminated structure according to the second embodiment, similar to the laminated structure according to the first embodiment, the buffer film 12 does not necessarily have to contain a first metal oxide epitaxially grown on the main surface 11p of the substrate 11, the conductive film 13 does not necessarily have to contain a platinum group element such as Pt epitaxially grown on the buffer film 12, and the conductive film 14 may contain SrRuO epitaxially grown on the conductive film 13. ３It does not have to include. Even in such cases, for example, by oriented the buffer film 12, the conductive film 13 and the conductive film 14 in a single direction, a dielectric film having an ilmenite-type structure and other various single-crystal high-quality dielectric films can be oriented in a certain direction on the Si substrate, so LiNbO ３ Or LiTaO ３ This material allows for easy epitaxial growth in a (01-12) oriented state or in a state oriented to a plane different from the (0001) plane, and enables the formation of a dielectric film with excellent crystallinity on a Si substrate.

[0054] Furthermore, the laminated structure according to the second embodiment, like the laminated structure according to the first embodiment, does not necessarily have a conductive film 13 and a conductive film 14, and the dielectric film 15 may be formed directly on the buffer film 12. Even in such a case, for example, the buffer film 12 may contain a first metal oxide epitaxially grown on the main surface 11p of the substrate 11, thereby providing LiNbO ３ Or LiTaO ３ The material is such that it can be easily epitaxially grown in a (01-12) oriented state or in a state oriented to a plane different from the (0001) plane, and a dielectric film with excellent crystallinity can be formed on the buffer film 12.

[0055] Figure 7 shows the LiNbO contained in the second metal oxide in the laminated structure of the second embodiment. ３ This is a schematic plan view showing the orientation state of the crystal lattice. Figure 8 shows the LiNbO contained in the second metal oxide in the stacked structure according to the second embodiment. ３ This is a schematic side view showing the orientation state of the crystal lattice. Also, in Figures 7 and 8, for the sake of ease of understanding, LiNbO is represented by a hexagonal crystal lattice instead of a trigonal one. ３ The crystal lattice is further represented by a rectangular prism, with hatching applied to the (0001) face.

[0056] As shown in Figures 7 and 8, it is preferable that each of the single dielectric layer 15a or the two to four dielectric layers 15a is oriented such that the (0001) plane of the second metal oxide is inclined with respect to the main plane by a first angle θ11, and that it contains a first domain DM1, a second domain DM2, a third domain DM3, and a fourth domain DM4 in which the

[0001] axes of the second metal oxide are oriented in different directions. ３ When this is the case, the first angle θ11 can be set to, for example, 52.24° to 62.24°. On the other hand, the second metal oxide is LiTaO ３ When this occurs, the first angle θ11 can be set to, for example, 52.02° to 62.02°.

[0057] Here, in the second domain DM2, LiNbO is included in the second metal oxide. ３ Or LiTaO ３ The

[0001] direction is such that, when viewed from the normal direction of the main surface 11p (around the normal direction of the main surface 11p), LiNbO contained in the second metal oxide in the first domain DM1 ３ Or LiTaO ３ This is the direction rotated 90° counterclockwise from the

[0001] direction. Also, in the third domain DM3, LiNbO contained in the second metal oxide ３ Or LiTaO ３ The

[0001] direction is such that, when viewed from the normal direction of the main surface 11p (around the normal direction of the main surface 11p), LiNbO contained in the second metal oxide in the first domain DM1 ３ Or LiTaO ３ This is the direction rotated 180° counterclockwise from the

[0001] direction. Also, in the fourth domain DM4, LiNbO contained in the second metal oxide ３ Or LiTaO ３ The

[0001] direction is such that, when viewed from the normal direction of the main surface 11p (around the normal direction of the main surface 11p), LiNbO contained in the second metal oxide in the first domain DM1 ３ Or LiTaO ３ This is the direction rotated 270° counterclockwise from the

[0001] direction.

[0058] In such cases, LiNbO contained in the metal nitride of the dielectric film 15 ３ Or LiTaO ３ Since it is oriented (01-12), LiNbO ３ Or LiTaO ３ The inclination angle of the (0001) surface relative to the main surface 11p can be easily controlled to be a constant angle. In addition, the (01-12) oriented LiNbO ３ The dielectric film 15 is made of 36° Y-cut LiNbO ３ It possesses an electromechanical coupling coefficient as high as that of a single crystal plate, as well as a high longitudinal wave velocity. Therefore, it is possible to realize electronic devices such as SAW filters with high electromechanical coupling coefficients and excellent filter characteristics.

[0059] The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples. Note that the following examples are hypothetical and not based on actual experiments.

[0060] (Example 1) [Formation of Laminated Structure] The laminated structure of Example 1 is the laminated structure described using Figure 1 above. As mentioned above, Example 1 is a hypothetical example and not an actual experiment. First, the crystal growth surface side of the Si(111) substrate, which serves as substrate 11 (see Figure 1), is treated with reactive ion etching (RIE), and a thermal oxide film is formed by heating in the presence of oxygen. Then, without using oxygen, the metal (Hf, Zr) of the deposition source and the oxygen in the oxide film on the Si substrate are thermally reacted by electron beam deposition to form a single crystal film of the first metal oxide as a buffer film 12 (see Figure 1) on the Si substrate ((1-1) initial metal nucleus). Next, oxygen is flowed, the temperature is lowered, and the pressure is increased to perform annealing ((1-2) post-annealing). Next, with oxygen flowing, the metal (Hf, Zr) of the deposition source and the oxygen are subjected to a thermal reaction to form a single crystal film of the first metal oxide as a buffer film 12 (see Figure 1) on the Si substrate ((1-3) HZO deposition).

[0061] The conditions for the electron beam deposition method during film formation can be as follows. The target values ​​for Hf:Zr are 25:75 (where x in the above composition formula (2) is 0.75). (1-1) Metal initial nucleation deposition source: Hf, Zr Pressure: 2 × 10 －４ Pa Thickness: 2 nm Substrate temperature: 1000°C (1-2) Post-annealing pressure: 2 × 10 －２ Pa Substrate temperature: 900°C Time: 180 sec (1-3) HZO deposition Evaporation source: Hf, Zr Pressure: 2 × 10 －２ Pa thickness: 10 nm, Substrate temperature: 900°C

[0062] Next, a metal film made of Pt is formed on the buffer film 12 as a conductive film 13 (see Figure 1) by sputtering. The conditions for this can be, for example, as follows: Apparatus: ULVAC sputtering apparatus QAM-4 Pressure: 1.20 × 10 －１ Pa Target: Pt Power: 100W (DC) Thickness: 80nm Substrate temperature: 450℃~600℃

[0063] Next, on the Pt metal film as conductive film 13, a conductive film 14 (see Figure 1) is made of SrRuO ３ A conductive film is formed by sputtering. The conditions for this process can be as follows, for example: Equipment: ULVAC sputtering apparatus QAM-4 Power: 150W (RF) Gas: Ar Pressure: 1.8 Pa Substrate temperature: 600℃ Thickness: 10 nm

[0064] Next, SrRuO as the conductive film 14 ３ On top of the conductive film made of LiNbO, a dielectric film 15 is made of LiNbO ３ A dielectric film 15 made of (LN) is formed by sputtering. The conditions for this can be, for example, as follows: Apparatus: RF magnetron sputtering apparatus Power: 2500W Gas: Ar / O ２Pressure: 0.14 Pa; Substrate temperature: 425-525°C; Thickness: 500 nm

[0065] In this way, LiNbO is placed on the conductive film 14. ３ The laminated structure of Example 1 is fabricated by forming a dielectric film 15 made of (LN) by sputtering. Although not shown in the example, a conductive film 13 made of Pt and SrRuO are formed on the buffer film 12. ３ Alternatively, the dielectric film 15 may be formed directly on the buffer film 12 without forming a conductive film 14.

[0066] [X-ray Diffraction Measurement] After forming a dielectric film 15 on the main surface 11p of the substrate 11, the laminated structure is arranged so that the diffraction plane in the X-ray diffraction (XRD) measurement using the θ-2θ method is parallel to the main surface 11p, and the diffraction pattern of the laminated structure is measured by the said X-ray diffraction measurement. The diffraction pattern of the laminated structure of the assumed embodiment 1 is shown in Figure 9. Note that the XRD measurement can be performed using the Rigaku SmartLab X-ray diffractometer.

[0067] As shown in Figure 9, in the diffraction pattern of Example 1, there is a strong diffraction peak of the (111) plane of Si, diffraction peaks of the (111) plane (HZO t(101)) and (222) plane (HZO t(202)) in the pseudocubic representation of HZO, a strong diffraction peak of the (111) plane of Pt, and LiNbO ３ A strong diffraction peak is observed on the (0006) plane (LN(006)) of (LN). From this result, in Example 1, the HZO contained in the buffer film 12 is (111) oriented in pseudocubic crystal representation, the Pt contained in the conductive film 13 has a cubic crystal structure and is (111) oriented, and the LiNbO contained in the second metal oxide in the dielectric film 15 ３ It is confirmed that (LN) has an ilmenite-type structure and is (0001) oriented.

[0068] Although not shown in the diagram, after forming the conductive film 14 on the main surface 11p of the substrate 11, and before forming the dielectric film 15, the diffraction pattern of the laminated structure is similarly measured to determine the amount of SrRuO contained in the conductive film 14.３ It is confirmed that (SRO) is oriented (111) in the pseudocubic crystal representation. Also, although not shown in the figure, LiNbO ３ By adjusting the film deposition conditions of (LN), the LiNbO contained in the second metal oxide in the dielectric film 15 can be obtained. ３ It is also confirmed that (LN) has an ilmenite-type structure and is (01-12) oriented.

[0069] Furthermore, although not shown in the diagram, the diffraction plane in the X-ray diffraction measurement is inclined with respect to the main surface 11p, and LiNbO ３ With the stacked structure positioned (X-adjusted) so that no diffraction peaks other than the diffraction peak of the (O1-12) plane of (LN) are observed, a φ scan is performed on the (O1-12) plane (2θ = 23.75°) of LN contained in the second metal oxide contained in the dielectric film 15.

[0070] Although not shown in the diagram, in the φ scan, LiNbO ３ Six strong diffraction peaks on the (01-12) plane of (LN) are observed at 60° intervals. That is, in the φ scan, diffraction peaks showing six-fold symmetry of LN are observed. Therefore, it is confirmed that the LN contained in the second metal oxide contained in the dielectric film 15 has its crystal axis aligned in the in-plane direction along the main surface 11p of the substrate 11, i.e., it has grown epitaxially.

[0071] Although a detailed explanation will be omitted, the dielectric film 15 is LiNbO ３ (LN) replaced with LiTaO ３ Even in the case where a second metal oxide consisting of (LT) is included, the dielectric film 15 is LiNbO ３ Similar results to those obtained in Example 1, which includes a second metal oxide consisting of (LN), can be obtained.

[0072] Furthermore, although a detailed explanation will be omitted, even when the ratio of Hf:Zr is a ratio other than 25:75, and x in the above compositional formula (2) satisfies 0 ≤ x < 1 or x satisfies x = 1, the same results as in Example 1, where the ratio of Hf:Zr is 25:75 (x in the above compositional formula (2) is 0.75), can be obtained.

[0073] (Example 2) [Formation of Laminated Structure] Next, the laminated structure of Example 2 is fabricated in the same manner as in Example 1, except that a Si(110) substrate is used instead of a Si(111) substrate as the substrate 11 (see Figure 1). As mentioned above, Example 2 is a hypothetical example and is not an actual experiment.

[0074] [X-ray diffraction measurement] After forming a dielectric film 15 on the main surface 11p of the substrate 11, the laminated structure is arranged so that the diffraction plane in the X-ray diffraction measurement using the θ-2θ method is parallel to the main surface 11p, and the diffraction pattern of the laminated structure is measured by the said X-ray diffraction measurement. The diffraction pattern of the laminated structure of the assumed embodiment 2 is shown in Figure 10.

[0075] As shown in Figure 10, in the diffraction pattern of Example 2, there is a strong diffraction peak on the (220) plane of Si, strong diffraction peaks on the (111) plane (HZO t(101)) and (222) plane (HZO t(202)) in the pseudocubic representation of HZO, a strong diffraction peak on the (111) plane of Pt, and LiNbO ３ Strong diffraction peaks are observed on the (01-12) plane (LN(012)) and the (0006) plane (LN(006)) of (LN). From these results, it can be seen that in Example 2, the HZO contained in the buffer film 12 is (111) oriented in pseudocubic crystal representation, the Pt contained in the conductive film 13 has a cubic crystal structure and is (111) oriented, and the LiNbO contained in the second metal oxide in the dielectric film 15 ３ (LN) is confirmed to have an ilmenite-type structure and to be (01-12) oriented or (0001) oriented.

[0076] Although not shown in the diagram, after forming the conductive film 14 on the main surface 11p of the substrate 11, and before forming the dielectric film 15, the diffraction pattern of the laminated structure is similarly measured to determine the amount of SrRuO contained in the conductive film 14. ３ It is confirmed that (SRO) is oriented in the (111) position in the pseudocubic crystal representation. Furthermore, the same results as in Example 2, in which the Si(110) substrate was used, are obtained when a Si(100) substrate is used instead of the Si(110) substrate.

[0077] When this Si(100) substrate is used, although not shown in the figure, the diffraction plane in the X-ray diffraction measurement is inclined with respect to the main surface 11p, and LiNbO ３ In order to prevent the strong observation of diffraction peaks other than the diffraction peak of the (01-12) plane of (LN), a φ scan is performed on the (01-12) plane (2θ = 23.75°) of LN contained in the second metal oxide contained in the dielectric film 15, with the stacked structure in an arranged state (X-adjusted state).

[0078] Although not shown in the diagram, in the φ scan, LiNbO ３ Four strong diffraction peaks on the (01-12) plane of (LN) are observed at 90° intervals. That is, in the φ scan, diffraction peaks showing four-fold symmetry of LN are observed. Therefore, it is confirmed that the crystal axes of LN contained in the second metal oxide contained in the dielectric film 15 are aligned in the in-plane direction along the main surface 11p of the substrate 11, i.e., they are epitaxially grown.

[0079] Although a detailed explanation will be omitted, the dielectric film 15 is LiNbO ３ (LN) replaced with LiTaO ３ Even in the case where a second metal oxide consisting of (LT) is included, the dielectric film 15 is LiNbO ３ Similar results to those obtained in Example 2, which includes a second metal oxide consisting of (LN), can be obtained.

[0080] Furthermore, although a detailed explanation will be omitted, even when the ratio of Hf:Zr is a ratio other than 25:75, and x in the above composition formula (2) satisfies 0 ≤ x < 1 or x satisfies x = 1, the same results as in Example 2, where the ratio of Hf:Zr is 25:75 (x in the above composition formula (2) is 0.75), can be obtained.

[0081] 10, 10a Laminated structure 11 Substrate 11a Base 11b Insulating layer 11c SOI layer 11p Main surface 12 Buffer film 13, 14 Conductive film 15 Dielectric film 15a Dielectric layer DM1 First domain DM2 Second domain DM3 Third domain DM4 Fourth domain DM5 Fifth domain DM6 Sixth domain

Claims

1. A laminated structure comprising a substrate, a buffer film formed on the substrate, and a dielectric film formed on the buffer film, wherein the substrate is a Si substrate, or an SOI substrate comprising a substrate made of a Si substrate, an insulating layer on the substrate, and an SOI layer made of a Si film on the insulating layer, and the buffer film contains a first metal oxide represented by the following composition formula (1): (Hf １－ｘ Zr ｘ ) O ２ ... (1) The x satisfies 0 ≤ x < 1 or x = 1, the dielectric film consists of only one first dielectric layer or only two to four second dielectric layers stacked on top of each other, each of the one first dielectric layer or the two to four second dielectric layers has an ilmenite-type structure and is oriented in a certain direction. ３ Or LiTaO ３ A laminated structure comprising a second metal oxide.

2. In the laminated structure according to claim 1, the substrate includes a main surface, the substrate is a Si(111) substrate including the main surface which is made of a Si(111) plane, or an SOI substrate including a base body, an insulating layer on the base body, and an SOI layer which is made of a Si(111) film on the insulating layer and includes the main surface which is made of a Si(111) plane, the buffer film is formed on the main surface and includes the first metal oxide which is (111) oriented in pseudocubic crystal representation, and each of the one first dielectric layer or the two to four second dielectric layers has an ilmenite-type structure and is (01-12) oriented LiNbO ３ Or LiTaO ３ A laminated structure comprising the second metal oxide.

3. The laminated structure according to claim 2, wherein the first metal oxide is epitaxially grown on the main surface, and the second metal oxide is LiNbO epitaxially grown on the buffer film ３ or LiTaO ３ A laminated structure consisting of 4. In the laminated structure according to claim 3, each of the first dielectric layer of the first layer or the second to fourth dielectric layers is oriented such that the (0001) plane of the second metal oxide is inclined by a first angle with respect to the main plane, and includes first, second, third, fourth, fifth, and sixth domains in which the [0001] axes of the second metal oxide are oriented in different directions from each other, wherein the second domain contains LiNbO ３ Or LiTaO ３ The [0001] direction is such that, when viewed from the direction normal to the main surface, the LiNbO contained in the second metal oxide in the first domain ３ Or LiTaO ３ This is a direction rotated 60° counterclockwise from the [0001] direction, and LiNbO contained in the second metal oxide in the third domain ３ Or LiTaO ３ The [0001] direction is such that, when viewed from the direction normal to the main surface, the LiNbO contained in the second metal oxide in the first domain ３ Or LiTaO ３ This is a direction rotated 120° counterclockwise from the [0001] direction, and LiNbO contained in the second metal oxide in the fourth domain ３ Or LiTaO ３ The [0001] direction is such that, when viewed from the direction normal to the main surface, the LiNbO contained in the second metal oxide in the first domain ３ Or LiTaO ３ This is a direction rotated 180° counterclockwise from the [0001] direction, and LiNbO contained in the second metal oxide in the fifth domain ３ Or LiTaO ３ The [0001] direction is such that, when viewed from the direction normal to the main surface, the LiNbO contained in the second metal oxide in the first domain ３ Or LiTaO ３ This is a direction rotated 240° counterclockwise from the [0001] direction, and LiNbO contained in the second metal oxide in the sixth domain ３ Or LiTaO ３ The [0001] direction is such that, when viewed from the direction normal to the main surface, the LiNbO contained in the second metal oxide in the first domain ３ Or LiTaO ３ A laminated structure, which is a direction rotated 300° counterclockwise from the [0001] direction.

5. The laminated structure according to claim 3, comprising a first conductive film formed on the buffer film, wherein the first conductive film is epitaxially grown on the buffer film, has a cubic crystal structure, and contains (111)-oriented platinum group elements, and the second metal oxide is LiNbO, epitaxially grown on the first conductive film. ３ Or LiTaO ３ A layered structure.

6. The laminated structure according to claim 5, wherein a second conductive film is formed on the first conductive film, the second conductive film contains strontium ruthenate epitaxially grown on the first conductive film and oriented (111) in pseudocubic crystal representation, and the second metal oxide is LiNbO epitaxially grown on the second conductive film. ３ Or LiTaO ３ A layered structure.

7. In the laminated structure according to claim 1, the substrate includes a main surface, the substrate is a Si(100) substrate including the main surface which is made of a Si(100) plane, or an SOI substrate including a base body, an insulating layer on the base body, and an SOI layer which is made of a Si(100) film on the insulating layer and includes the main surface which is made of a Si(100) plane, the buffer film is formed on the main surface and includes the first metal oxide which is (100) oriented in pseudocubic crystal representation, and each of the one first dielectric layer or the two to four second dielectric layers has an ilmenite-type structure and is (01-12) oriented LiNbO ３ Or LiTaO ３ A laminated structure comprising the second metal oxide.

8. In the laminated structure according to claim 7, the first metal oxide is epitaxially grown on the main surface, and the second metal oxide is epitaxially grown on the buffer film. ３ Or LiTaO ３ A layered structure.

9. In the laminated structure according to claim 8, each of the first dielectric layer of the first layer or the second to fourth dielectric layers of the second layer is oriented such that the (0001) plane of the second metal oxide is inclined by a first angle with respect to the main plane, and includes a first domain, a second domain, a third domain and a fourth domain in which the [0001] axes of the second metal oxide are oriented in different directions from each other, wherein the second domain contains LiNbO ３ Or LiTaO ３ The [0001] direction is such that, when viewed from the direction normal to the main surface, the LiNbO contained in the second metal oxide in the first domain ３ Or LiTaO ３ This is a direction rotated 90° counterclockwise from the [0001] direction, and LiNbO contained in the second metal oxide in the third domain ３ Or LiTaO ３ The [0001] direction is such that, when viewed from the direction normal to the main surface, the LiNbO contained in the second metal oxide in the first domain ３ Or LiTaO ３ This is a direction rotated 180° counterclockwise from the [0001] direction, and LiNbO contained in the second metal oxide in the fourth domain ３ Or LiTaO ３ The [0001] direction is such that, when viewed from the direction normal to the main surface, the LiNbO contained in the second metal oxide in the first domain ３ Or LiTaO ３ A laminated structure, which is a direction rotated 270° counterclockwise from the [0001] direction.

10. The laminated structure according to claim 8, wherein a first conductive film is formed on the buffer film, the first conductive film is epitaxially grown on the buffer film, has a cubic crystal structure, and contains (100)-oriented platinum group elements, and the second metal oxide is LiNbO, epitaxially grown on the first conductive film. ３ Or LiTaO ３ A layered structure.

11. The laminated structure according to claim 10, wherein a second conductive film is formed on the first conductive film, the second conductive film contains strontium ruthenate epitaxially grown on the first conductive film and oriented (100) in pseudocubic crystal representation, and the second metal oxide is LiNbO epitaxially grown on the second conductive film. ３ Or LiTaO ３ A layered structure.

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