Laminated structure and electronic device

Abstract

A laminated structure (10) comprises: a substrate (11) including a main surface (11p); a buffer film (12) formed on the main surface (11p); and a metal film (14) formed on the buffer film (12). The substrate (11) is composed of a Si substrate, or an SOI substrate including: a base body composed of a Si substrate; an insulating layer on the base body; and an SOI layer on the insulating layer. The buffer film (12) is made of a first metal oxide represented by the following compositional formula (Chemical Formula 1), where x satisfies 0 ≤ x < 1 or satisfies x = 1. The metal film (14) contains Fe, Cu, Mo, W, Ag, Al, Ti, or Ir as a main component. (Chemical Formula 1): (Hf1-xZrx)O2

Description

Laminated structure and electronic device

[0001] The present invention relates to a laminated structure and an electronic device.

[0002] A laminated structure having a substrate and a metal film formed on the substrate, and an electronic device including the laminated structure are known, such as a magnetic recording medium having a magnetic recording film made of a metal film, and a semiconductor integrated circuit having a wiring layer made of a metal film.

[0003] Japanese Patent Laid-Open Publication No. 03-257905 (Patent Document 1) discloses a technology for a stainless steel thin film for magnetic recording that contains 15 wt% to 24 wt% Ni and 16.5 wt% to 19 wt% Cr, and is grown on a substrate by vapor phase quenching to form a microstructure in which fine crystallites of a ferromagnetic phase and fine crystallites of a non-magnetic phase coexist. Japanese Patent Laid-Open Publication No. 2024-061965 (Patent Document 2) discloses a technology for a laminated structure that includes at least a piezoelectric film and a metal film containing a metal as a main component, the metal being a metal that undergoes martensitic transformation by heat treatment or processing, and the metal containing Fe and Cr.

[0004] Japanese Patent Laid-Open Publication No. 07-054162 (Patent Document 3) discloses a technique for forming a metal thin film, which includes a step of laminating a Cu thin film on a base layer, a step of annealing the Cu thin film, and a step of epitaxially growing a metal thin film on the Cu thin film.

[0005] JP 03-257905 JP 2024-061965 JP 07-054162

[0006] LS Fan et al., “Stabilizing Ir(001) epitaxy on yttria-stabilized zirconia using a thin Ir seed layer grown by pulsed laser deposition”, Crystal Growth and Design 17 (2017) 89-94

[0007] The technology described in Patent Document 1 cannot form a single-crystal stainless steel thin film on a substrate, so it is difficult to improve the uniformity of physical properties such as magnetization characteristics of the entire stainless steel thin film and improve the smoothness of the film surface. Even with the technology described in Patent Document 2, it is desirable to further improve the electrical conductivity of the entire metal film and further improve the smoothness of the film surface.

[0008] In the technique described in Patent Document 3, when a Cu thin film stacked on an underlayer is annealed, the Cu thin film is strongly oriented in the (111) plane because Cu has a face-centered cubic structure. As a result, it is not possible to form a single-crystal Cu thin film on the underlayer, making it difficult to improve the electrical conductivity of the entire Cu thin film and the smoothness of the film surface.

[0009] The present invention aims to provide a laminated structure having a metal film formed on a substrate, and an electronic device equipped with the laminated structure, in which a single-crystal metal film is formed on a substrate, thereby improving the physical properties of the metal film, such as the magnetization characteristics or electrical conductivity, and improving the smoothness of the film surface, and an electronic device equipped with the laminated structure.

[0010] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by the following configuration: [1] A stacked structure having a substrate including a main surface, a first buffer film formed on the main surface, and a first metal film formed on the first buffer film, wherein the substrate is a Si substrate or an SOI substrate including a base body made of a Si substrate, an insulating layer on the base body, and an SOI layer on the insulating layer, and the first buffer film is made of a first metal oxide represented by the following composition formula (Chemical Formula 1): (Hf １－ｘ Zr ｘ ) O ２... (Chemical Formula 1) The x satisfies 0≦x<1 or satisfies x=1, and the first metal film contains Fe, Cu, Mo, W, Ag, Al, Ti, or Ir as a main component. [2] The stacked structure according to [1], further comprising a second metal film formed on the first buffer film, the first metal film being formed on the second metal film, and the second metal film being made of Pt. [3] The stacked structure according to [2], wherein the first buffer film is made of the first metal oxide epitaxially grown on the main surface, the second metal film is made of Pt epitaxially grown on the first buffer film, and the first metal film is epitaxially grown on the second metal film. [4] The stacked structure according to [2] or [3], wherein the substrate is a Si(100) substrate having a main surface formed of a Si(100) plane, or an SOI substrate including a base body formed of a Si substrate, an insulating layer on the base body, and an SOI layer formed of a Si(100) film on the insulating layer and having a main surface formed of a Si(100) plane, the first buffer film is made of the first metal oxide having a (100) orientation in pseudo cubic notation, and the second metal film has a cubic crystal structure and is (100) oriented. [5] The stacked structure according to [4], wherein the first metal film contains Fe, has a cubic crystal structure and is (100) oriented. [6] The stacked structure according to [5], wherein the first metal film contains Cr or Ni. [7] The stacked structure according to [4], wherein the first metal film contains Cu, has a cubic crystal structure, and is (100) oriented. [8] The stacked structure according to [4], wherein the first metal film contains Mo, has a cubic crystal structure, and is (110) oriented. [9] The stacked structure according to [4], wherein the first metal film contains W, has a cubic crystal structure, and is (110) oriented.

[10] The stacked structure according to [4], wherein the first metal film contains Ag, has a cubic crystal structure, and is (100) oriented.

[11] The stacked structure according to [4], wherein the first metal film contains Al, has a cubic crystal structure, and is (100) oriented.

[12] The stacked structure according to [4], wherein the first metal film contains Ti, has a cubic crystal structure, and is (110) oriented.

[13] The stacked structure according to [4], wherein the first metal film contains Ir, has a cubic crystal structure, and is (100) oriented.

[14] The stacked structure according to [2] or [3], wherein the substrate is a Si(111) substrate having a main surface formed of a Si(111) plane, or an SOI substrate including the base formed of a Si substrate, the insulating layer on the base, and the SOI layer on the insulating layer, which is a Si(111) film and has the main surface formed of a Si(111) plane, the first buffer film is made of the first metal oxide having a (111) orientation in pseudo cubic notation, and the second metal film has a cubic crystal structure and is (111) oriented.

[15] The stacked structure according to

[14] , wherein the first metal film contains Ir, has a cubic crystal structure, and is (111) oriented.

[16] The first buffer film includes: a second buffer film formed on the main surface, a third buffer film formed on the second buffer film, and a fourth buffer film formed on the third buffer film, wherein the second buffer film is made of a second metal oxide represented by the following composition formula (Chemical Formula 2): (Hf. １－ｘ１－ｙ１ Zr ｘ１ M ｙ１ ) O ２－ｚ１ ... (Chemical Formula 2) (wherein, in the composition formula (Chemical Formula 2), M is at least one selected from the group consisting of Nb, Ta, Si, Ti, rare earth elements, Al, and Group 2 elements). The y1 satisfies 0<y1≦0.3, and the x1 satisfies 0≦x1≦1−y1. The third buffer film is made of a third metal oxide represented by the following composition formula (Chemical Formula 3), (RE ｘ２ Al ｙ２ ) O ｚ２ ... (Chemical Formula 3) (In the composition formula (Chemical Formula 3), RE is one or more elements selected from the group consisting of rare earth elements.) The stacked structure according to

[13] or

[15] , wherein the fourth buffer film is made of a fourth metal oxide containing Ce.

[17] An electronic device comprising the stacked structure according to any one of [1] to

[15] .

[0011] The laminated structure of the present invention and an electronic device including the laminated structure can form a single-crystal metal film on a substrate, improve the physical properties of the metal film, such as the magnetization characteristics or electrical conductivity, and improve the smoothness of the film surface.

[0012] FIG. 1 is a cross-sectional view showing an example of a laminate structure according to embodiment 1. FIG. 2 is a cross-sectional view showing another example of a laminate structure according to embodiment 1. FIG. 3 is a cross-sectional view showing another example of a laminate structure according to embodiment 1. FIG. 4 is a cross-sectional view showing another example of a laminate structure according to embodiment 1. FIG. 5 is a cross-sectional view showing another example of a laminate structure according to embodiment 1. FIG. 6 is a cross-sectional view showing another example of a laminate structure according to embodiment 1. FIG. 7 is a cross-sectional view showing another example of a laminate structure according to embodiment 1. FIG. 8 is a cross-sectional view showing another example of a laminate structure according to embodiment 1. FIG. 9 is a cross-sectional view showing an example of a laminate structure according to a modification of embodiment 1. FIG. 10 is a cross-sectional view showing another example of a laminate structure according to embodiment 1. FIG. 11 is a cross-sectional view showing an electronic device according to embodiment 2. FIG. 12 is a graph showing a diffraction pattern of the laminate structure according to example 1. FIG. 13 is a graph showing a φ scan of the laminate structure according to example 1. FIG. 14 is a graph showing a diffraction pattern of the laminate structure according to example 1. FIG. 15 is a graph showing a φ scan of the laminate structure according to example 1. FIG. 16 is a graph showing a diffraction pattern of the laminate structure according to example 2. FIG. 17 is a graph showing a φ scan of the laminate structure according to example 2. FIG. 18 is a graph showing a diffraction pattern of the laminate structure according to example 3. FIG. 19 is a graph showing a φ scan of the laminate structure according to example 3. FIG. 19 is a graph showing a diffraction pattern of the laminate structure according to example 4. FIG. 19 is a graph showing a φ scan of the laminate structure according to example 4. Graph showing the diffraction pattern of the laminate structure of Example 5. Graph showing the φ scan of the laminate structure of Example 5. Graph showing the diffraction pattern of the laminate structure of Example 6. Graph showing the diffraction pattern of the laminate structure of Example 6. Graph showing the φ scan of the laminate structure of Example 6. Graph showing the diffraction pattern of the laminate structure of Example 7. Graph showing the diffraction pattern of the laminate structure of Example 7. Graph showing the diffraction pattern of the laminate structure of Example 7. Graph showing the φ scan of the laminate structure of Example 7. Graph showing the diffraction pattern of the laminate structure of Example 8. Graph showing the diffraction pattern of the laminate structure of Example 8. Graph showing the φ scan of the laminate structure of Example 8. Graph showing the diffraction pattern of the laminate structure of Example 9. Graph showing the φ scan of the laminate structure of Example 9.

[0013] Hereinafter, each embodiment of the present invention will be described with reference to the drawings.

[0014] (First Embodiment) <Laminated Structure> First, a laminated structure according to the first embodiment will be described. Fig. 1 is a cross-sectional view showing an example of the laminated structure according to the first embodiment. Figs. 2 to 4 are cross-sectional views showing other examples of the laminated structure according to the first embodiment.

[0015] The stacked structure 10 shown in Figures 1 and 2 has a substrate 11 including a main surface 11p, a buffer film (first buffer film) 12 formed on the main surface 11p, a metal film (second metal film) 13 formed on the buffer film 12, and a metal film (first metal film) 14 formed on the metal film (second metal film) 13.

[0016] 1, the substrate 11 is a silicon (Si)(100) substrate including a main surface 11p of a Si(100) plane. In the example shown in Fig. 2, the substrate 11 is an SOI (silicon-on-insulator) substrate including a base 11a of a Si substrate, an insulating layer 11b on the base 11a, and an SOI (silicon-on-insulator) layer 11c on the insulating layer 11b, which is a Si(100) film and includes the main surface 11p of the Si(100) plane.

[0017] The buffer film 12 is epitaxially grown on the main surface 11p, has a (100) orientation in pseudo-cubic crystal representation, and is made of a first metal oxide represented by the following composition formula (Chemical Formula 4): (Hf １－ｘ Zr ｘ ) O ２ ... (Chemical Formula 4) In the above composition formula (Chemical Formula 4), x satisfies 0≦x<1 or satisfies x=1. Note that the above composition formula (Chemical Formula 4) is the same composition formula as the above composition formula (Chemical Formula 1). Furthermore, instead of the first metal oxide represented by the above composition formula (Chemical Formula 4), a metal oxide represented by the below-described composition formula (Chemical Formula 5) can also be used.

[0018] In the present specification, the term "metal oxide is (100) oriented in pseudocubic crystal notation" means that the metal oxide has a cubic crystal structure at room temperature and is (100) oriented, or that even if it has a tetragonal or monoclinic crystal structure at room temperature, it undergoes a phase transition at high temperature to form a cubic crystal structure and is (100) oriented. In the following, among the first metal oxides represented by the above composition formula (Chemical Formula 4), when x = 0, HfO ２ and when x=1, ZrO ２ However, when 0<x<1 is satisfied, it is sometimes called HZO.

[0019] The metal film 13 is epitaxially grown on the buffer film 12 and is made of platinum (Pt). The metal film 13 has a cubic crystal structure and is (100) oriented. That is, the metal film 13 is (100) oriented in the cubic crystal representation.

[0020] The metal film 14 is epitaxially grown on the metal film 13 and contains iron (Fe), copper (Cu), molybdenum (Mo), tungsten (W), silver (Ag), aluminum (Al), titanium (Ti), or iridium (Ir) as a main component.

[0021] Patent Document 1 discloses a technique for forming a stainless steel thin film for magnetic recording, containing 15 wt% to 24 wt% Ni and 16.5 wt% to 19 wt% Cr, grown on a substrate by vapor phase quenching to form a microstructure containing a mixture of fine crystallites of ferromagnetic and non-magnetic phases. However, the technique described in Patent Document 1 does not allow for the formation of a single-crystal stainless steel thin film on a substrate, making it difficult to improve the physical properties of the entire stainless steel thin film, such as the magnetization characteristics, and to improve the surface smoothness of the film. Patent Document 2 also discloses a technique for a laminated structure including at least a piezoelectric film and a metal film containing a metal as a main component, the metal being a metal that undergoes martensitic transformation upon heat treatment or processing, and including Fe and Cr. However, the technique described in Patent Document 2 would be desirable to further improve the electrical conductivity of the entire metal film and the surface smoothness of the film.

[0022] Furthermore, Patent Document 3 discloses a method for forming a metal thin film, which includes the steps of stacking a Cu thin film on a substrate, annealing the Cu thin film, and epitaxially growing a metal thin film on the Cu thin film. However, with the technique described in Patent Document 3, when the Cu thin film stacked on the substrate is annealed, the Cu thin film is strongly oriented in the (111) plane because Cu has a face-centered cubic structure. As a result, it is not possible to form a single-crystalline Cu thin film on the substrate, making it difficult to improve the physical properties of the entire Cu thin film, such as the electrical conductivity or thermal conductivity, and to improve the smoothness of the film surface.

[0023] On the other hand, in the laminated structure of the first embodiment, HfO represented by the above composition formula (Chemical Formula 4) is formed on the substrate 11 made of a Si substrate or an SOI substrate. ２ , HZO or ZrO ２ The metal film 14 is formed via the buffer film 12 made of Pt and the metal film 13 made of Pt. In the stacked structure of the first embodiment, when the Si substrate is a Si(100) substrate or the SOI layer includes a Si(100) surface, the HfO ２ , HZO or ZrO ２ The buffer film 12 made of HfO 3 is oriented in the (100) direction in the pseudo cubic crystal notation, and the metal film 13 is oriented in the (100) direction in the cubic crystal notation. ２ , HZO or ZrO ２ The buffer film 12 is made of a first metal oxide epitaxially grown on the main surface 11p of the substrate 11, the metal film 13 is made of Pt epitaxially grown on the buffer film 12, and the metal film 14 is easily grown epitaxially on the metal film 13.

[0024] Therefore, according to the first embodiment, the metal film 14 containing Fe as a main component, for example, stainless steel as a main component, can be easily epitaxially grown on the metal film 13, and thus a single-crystal stainless steel thin film can be easily formed on the substrate 11. This improves the homogeneity of the physical properties, such as the magnetization characteristics, of the entire stainless steel thin film, and improves the smoothness of the film surface. Furthermore, in a laminate structure including at least a piezoelectric film and a metal film containing a metal as a main component, the electrical conductivity of the entire film can be further improved, and the smoothness of the film surface can be further improved.

[0025] Furthermore, according to the first embodiment, the metal film 14 containing Cu as a main component can be easily epitaxially grown on the metal film 13, so that a single-crystal Cu film can be easily formed on the substrate 11. Therefore, the electrical conductivity of the entire Cu film can be improved, and the smoothness of the film surface can be improved.

[0026] Furthermore, according to the first embodiment, the metal film 14 containing Mo, W, Ag, Al, Ti, or Ir as a main component can be easily epitaxially grown on the metal film 13, and therefore the single-crystal metal film 14 can be easily formed on the substrate 11. Therefore, the electrical conductivity of the entire metal film 14 containing Mo, W, Ag, Al, Ti, or Ir as a main component can be improved, and the smoothness of the film surface can be improved.

[0027] According to the first embodiment, a HfO ２ , HZO or ZrO ２ The metal film 13 and the metal film 14 can be easily epitaxially grown through the buffer film 12 made of HfO. ２ , HZO or ZrO ２ This is thought to be due to a crystal growth mechanism in which the dynamic lattice matching effect due to the twin martensitic transformation exhibited by the twist acts as a driving force, a prime mover, and a driving force during the epitaxial growth of the metal films 13 and 14. However, the present invention is not necessarily bound by such a theory.

[0028] In the laminated structure of the first embodiment, HfO ２ , HZO or ZrO ２ The metal film 14 is formed on the substrate 11 via the buffer film 12 made of HfO and the metal film 13 made of Pt. ２ , HZO or ZrO ２ The metal film 14 is not limited to being formed via the buffer film 12 made of HfO and the metal film 13 made of Pt. ２ , HZO or ZrO ２ The metal film 14 may be formed on the buffer film 12 without the metal film 13 made of Pt therebetween.

[0029] Furthermore, in the stacked structure of the first embodiment, buffer film 12 does not have to be made of a first metal oxide epitaxially grown on main surface 11p of substrate 11, metal film 13 does not have to be made of Pt epitaxially grown on buffer film 12, and metal film 14 does not have to be epitaxially grown on metal film 13. Even in such cases, each crystal grain of metal film 14 can be epitaxially grown on each crystal grain of metal film 13. However, when buffer film 12 is made of a first metal oxide epitaxially grown on main surface 11p of substrate 11, metal film 13 is made of Pt epitaxially grown on buffer film 12, and metal film 14 is epitaxially grown on metal film 13, metal film 14 can be epitaxially grown more easily on metal film 13.

[0030] In the stacked structure of the first embodiment, the substrate 11 does not have to be a Si(100) substrate including a main surface 11p made of a Si(100) plane or an SOI substrate including an SOI layer including a main surface 11p made of a Si(100) plane, the buffer film 12 does not have to be made of a first metal oxide oriented in the (100) direction in the pseudo cubic crystal representation, and the metal film 13 does not have to be oriented in the (100) direction in the cubic crystal representation. However, when the substrate 11 is a Si(100) substrate including a main surface 11p made of a Si(100) plane or an SOI substrate including an SOI layer including a main surface 11p made of a Si(100) plane, the buffer film 12 is made of a first metal oxide oriented in the (100) direction in the pseudo cubic crystal representation, and the metal film 13 is oriented in the (100) direction in the cubic crystal representation, the metal film 14 can be more easily epitaxially grown on the metal film 13.

[0031] The metal film 14 preferably contains Fe, has a cubic crystal structure, and is (100) oriented, i.e., contains Fe and is (100) oriented in cubic crystal notation. In such a case, the metal film 14 preferably further contains Cr or Ni, which allows the metal film 14 to be a metal film made of stainless steel. That is, the metal film 14 preferably contains Fe or Cr, or Fe or Ni.

[0032] It is preferable that the metal film 14 contains Cu, has a cubic crystal structure, and is (100) oriented, i.e., contains Cu and is (100) oriented in cubic crystal notation. In such a case, the metal film 14 containing Cu as a main component can be easily epitaxially grown on the metal film 13, so that a single-crystalline Cu film can be easily formed on the substrate 11. This can improve the electrical conductivity of the entire Cu film and the smoothness of the film surface.

[0033] It is preferable that the metal film 14 contains Mo, has a cubic crystal structure, and is (110) oriented, i.e., contains Mo and is (110) oriented in cubic crystal notation. In such a case, a piezoelectric film made of, for example, AlN can be easily formed on the metal film 14 with the AlN orientation controlled, and therefore a piezoelectric element having the piezoelectric film can be easily formed.

[0034] It is preferable that the metal film 14 contains W, has a cubic crystal structure, and is (110) oriented, i.e., contains W and is (110) oriented in cubic crystal notation. In such a case, a piezoelectric film made of, for example, AlN can be easily formed on the metal film 14 with the AlN orientation controlled, and therefore a piezoelectric element having the piezoelectric film can be easily formed.

[0035] It is preferable that the metal film 14 contains Ag, has a cubic crystal structure, and is (100) oriented, i.e., contains Ag and is (100) oriented in cubic crystal notation. In such a case, the metal film 14 containing Ag as a main component can be easily epitaxially grown on the metal film 13, so that a single-crystalline Ag film can be easily formed on the substrate 11. This can improve the electrical conductivity of the entire Ag film and the smoothness of the film surface.

[0036] It is preferable that the metal film 14 contains Al, has a cubic crystal structure, and is (100) oriented, i.e., contains Al and is (100) oriented in cubic crystal notation. In such a case, the metal film 14 containing Al as a main component can be easily epitaxially grown on the metal film 13, so that a single-crystalline Al film can be easily formed on the substrate 11. This can improve the electrical conductivity of the entire Al film and the smoothness of the film surface.

[0037] It is preferable that the metal film 14 contains Ti, has a cubic crystal structure, and is (110) oriented, i.e., contains Ti and is (110) oriented in cubic crystal notation. In such a case, a piezoelectric film made of, for example, AlN can be easily formed on the metal film 14 with the AlN orientation controlled, and therefore a piezoelectric element having the piezoelectric film can be easily formed.

[0038] It is preferable that the metal film 14 contains Ir, has a cubic crystal structure, and is (100) oriented, i.e., contains Ir and is (100) oriented in cubic crystal notation. In such a case, the metal film 14 containing Ir as a main component can be easily epitaxially grown on the metal film 13, so that a single-crystalline Ir film can be easily formed on the substrate 11. This can improve the electrical conductivity of the entire Ir film and the smoothness of the film surface.

[0039] When the metal film 14 contains Ir, the buffer film 12 is preferably epitaxially grown on the main surface 11p, oriented in the (100) direction in the pseudo-cubic crystal representation, and made of a metal oxide represented by the following composition formula (Chemical Formula 5): (Hf １－ｘ－ｙ－ｚ Zr ｘ Y ｙ Al ｚ ) O ２－ｕ In the above composition formula (Chemical Formula 5), ​​x satisfies 0≦x<1, y satisfies 0<y≦0.3, and z satisfies 0<z≦0.3. That is, the metal oxide represented by the above composition formula (Chemical Formula 5) is the first metal oxide represented by the above composition formula (Chemical Formula 4), i.e., HfO ２ , HZO or ZrO ２ The metal film 14 is a metal oxide in which metal oxides of one or more metals selected from the group consisting of Y and Al are added to the Ir. In such a case, the Ir contained in the metal film 14 has a cubic crystal structure, is (100) oriented, and is prone to epitaxial growth.

[0040] 5 and 6 are cross-sectional views showing other examples of the stacked structure of Embodiment 1. When the metal film 14 contains Ir, the buffer film 12 preferably includes a buffer film (second buffer film) 12a formed on the main surface 11p, a buffer film (third buffer film) 12b formed on the buffer film 12a, and a buffer film (fourth buffer film) 12c formed on the buffer film 12b, as shown in FIGS.

[0041] The buffer film 12a is epitaxially grown on the main surface 11p, has a (100) orientation in pseudo-cubic crystal notation, and is made of a second metal oxide represented by the following composition formula (Chemical Formula 6): (Hf １－ｘ１－ｙ１ Zr ｘ１ M ｙ１ ) O ２－ｚ１ ...(Chemical Formula 6) In the above composition formula (Chemical Formula 6), M is one or more elements selected from the group consisting of Nb, Ta, Si, Ti, rare earth elements, Al, and Group 2 elements, y1 satisfies 0<y1≦0.3, and x1 satisfies 0≦x1≦1−y1. Note that the above composition formula (Chemical Formula 6) is the same composition formula as the above composition formula (Chemical Formula 2). Furthermore, like the buffer film 12, the buffer film 12a does not need to be epitaxially grown. Furthermore, hereinafter, among the second metal oxides represented by the above composition formula (Chemical Formula 6), when M is yttrium (Y) and x1=1, they may be referred to as yttria-stabilized zirconia (YSZ), and when M is Y and x1=0, they may be referred to as yttria-stabilized hafnia (YSH).

[0042] The buffer film 12b is epitaxially grown on the buffer film 12a, has a (100) orientation in pseudocubic crystal notation, and is made of a third metal oxide represented by the following composition formula (Chemical Formula 7): (RE ｘ２ Al ｙ２ ) O ｚ２ ...(Chemical Formula 7) In the above composition formula (Chemical Formula 7), RE is one or more elements selected from the group consisting of rare earth elements. Note that the above composition formula (Chemical Formula 7) is the same as the above composition formula (Chemical Formula 3). Furthermore, like the buffer film 12, the buffer film 12b does not need to be epitaxially grown.

[0043] The buffer film 12c is epitaxially grown on the buffer film 12b, has a (100) orientation in a pseudo cubic crystal representation, and is made of a fourth metal oxide containing Ce. Note that, like the buffer film 12, the buffer film 12c does not have to be epitaxially grown.

[0044] In the technique described in the above-mentioned Non-Patent Document 1, when an Ir (001) film is epitaxially grown on a Si substrate via a buffer film made of YSZ, it is necessary to grow the film at a low growth rate of about 0.05 nm / s. On the other hand, in the present embodiment 1, a buffer film made of a second metal oxide, for example, YSZ or YSH, is interposed between the buffer film 12a and the metal film 14 made of Ir. ３ The buffer film 12b is made of a third metal oxide, for example, CeO ２ In this case, a buffer film 12c made of a fourth metal oxide containing Ir and a metal film 13 made of Pt are formed. In this case, a metal film 14 made of Ir can be epitaxially grown, and the growth rate of the metal film 14 can be significantly improved compared to the growth rate of the metal film 14 when the buffer film 12b, the buffer film 12c, and the metal film 13 are not formed between the buffer film 12a and the metal film 14.

[0045] When the metal film 14 contains Ir, the buffer film 12 preferably further includes a buffer film (fifth buffer film) 12d formed on the buffer film 12b, as shown in Figure 5. The buffer film 12d is epitaxially grown on the buffer film 12b, has a (100) orientation in pseudo-cubic crystal notation, and is made of the second metal oxide represented by the composition formula (Chemical Formula 6) or the first metal oxide represented by the composition formula (Chemical Formula 4). The buffer film 12c is epitaxially grown on the buffer film 12d. In such a case, for example, YAlO ３ and a buffer film 12b made of a third metal oxide, for example, CeO ２ This prevents the buffer film 12d from contacting the buffer film 12c made of the fourth metal oxide, which further facilitates epitaxial growth of the metal film 14 made of Ir. Note that, like the buffer film 12, the buffer film 12d does not have to be epitaxially grown.

[0046] Although not shown, the buffer film 12 includes the buffer film 12 a, the buffer film 12 b, and the buffer film 12 d, but does not necessarily include the buffer film 12 c. However, as described above, when the buffer film 12 includes the buffer film 12 c, the metal film 14 made of Ir can be epitaxially grown, and the growth rate of the metal film 14 can be improved.

[0047] The buffer film 12a made of a second metal oxide, for example, YSZ or YSH, is formed between the main surface 11p of the substrate 11 and a layer of, for example, YAlO ３ The third metal oxide, for example, CeO ２ The buffer film 12c made of the fourth metal oxide containing Pt has a function of preventing contact between the buffer film 12b and the metal film 13 made of Pt. Therefore, as shown in FIG. 6, the thickness of the buffer film 12a is preferably thinner than the thickness of the buffer film 12b, and the thickness of the buffer film 12c is preferably thinner than the thickness of the buffer film 12b.

[0048] <Modification of stacked structure> Next, a modification of the stacked structure of the first embodiment will be described. The stacked structure of this modification differs from the stacked structure of the first embodiment in that the substrate is a Si(111) substrate or an SOI substrate including an SOI layer including a main surface made of a Si(111) plane. Fig. 7 is a cross-sectional view showing an example of the stacked structure of the modification of the first embodiment. Fig. 8 is a cross-sectional view showing another example of the stacked structure of the modification of the first embodiment.

[0049] Similar to the stacked structure 10 shown in FIGS. 1 and 2, the stacked structure 10a shown in FIG. 7 also has a substrate 11 including a main surface 11p, a buffer film 12 formed on the main surface 11p, a metal film (second metal film) 13 formed on the buffer film 12, and a metal film (first metal film) 14 formed on the metal film (second metal film) 13.

[0050] 7, unlike the example shown in FIG. 1, the substrate 11 is made of a Si(111) substrate including a main surface 11p made of a Si(111) plane. Although not shown, the substrate 11 may be made of an SOI substrate, similar to the example shown in FIG. 2. In this case, the substrate 11 is made of an SOI substrate including a base 11a made of a Si substrate, an insulating layer 11b on the base 11a, and an SOI layer 11c made of a Si(111) film on the insulating layer 11b and including a main surface 11p made of a Si(111) plane.

[0051] The buffer film 12 is epitaxially grown on the main surface 11p, has a (111) orientation in pseudocubic notation, and is made of a first metal oxide represented by the above composition formula (Chemical Formula 4), where x satisfies 0≦x<1 or satisfies x=1.

[0052] The metal film 13 is epitaxially grown on the buffer film 12 and is made of Pt. The Pt contained in the metal film 13 has a cubic crystal structure and is (111) oriented. That is, the Pt contained in the metal film 13 is (100) oriented in cubic crystal notation.

[0053] The metal film 14 is epitaxially grown on the metal film 13 and contains Fe, Cu, Mo, W, Ag, Al, Ti or Ir as a main component.

[0054] In the laminated structure of this modification, similarly to the laminated structure of the first embodiment, the metal film 14 containing Fe, Cu, Mo, W, Ag, Al, Ti, or Ir as a main component can be easily epitaxially grown on the metal film 13, and therefore the single-crystal metal film 14 can be easily formed on the substrate 11. Therefore, the electrical conductivity of the entire metal film 14 containing Fe, Cu, Mo, W, Ag, Al, Ti, or Ir as a main component can be improved, and the smoothness of the film surface can be improved.

[0055] As in the first embodiment, the laminated structure of this modification also includes HfO ２ , HZO or ZrO ２Alternatively, the metal film 14 may be formed on the buffer film 12 made of Pt without the metal film 13 made of Pt interposed therebetween. Also, in the stacked structure of this modification, similar to the stacked structure of the first embodiment, the buffer film 12 does not have to be made of the first metal oxide epitaxially grown on the main surface 11p of the substrate 11, the metal film 13 does not have to be made of Pt epitaxially grown on the buffer film 12, and the metal film 14 does not have to be epitaxially grown on the metal film 13.

[0056] It is preferable that the metal film 14 contains Ir, has a cubic crystal structure, and is (111) oriented, i.e., contains Ir and is (111) oriented in cubic crystal representation. In such a case, the metal film 14 containing Ir as a main component can be easily epitaxially grown on the metal film 13, so that a single-crystalline Ir film can be easily formed on the substrate 11. This can improve the electrical conductivity of the entire Ir film and the smoothness of the film surface.

[0057] When the metal film 14 contains Ir, the buffer film 12 preferably grows epitaxially on the main surface 11p, has a (111) orientation in pseudo-cubic notation, and is made of a metal oxide represented by the above composition formula (Chemical Formula 5). In the above composition formula (Chemical Formula 5), ​​x satisfies 0≦x<1, y satisfies 0<y≦0.3, and z satisfies 0<z≦0.3. In such a case, the Ir contained in the metal film 14 has a cubic crystal structure, is (100) oriented, and is prone to epitaxial growth.

[0058] Furthermore, in the stacked structure of this modification, similar to the stacked structure of the first embodiment, when the metal film 14 contains Ir, the buffer film 12 preferably includes a buffer film (second buffer film) 12a formed on the main surface 11p, a buffer film (third buffer film) 12b formed on the buffer film 12a, and a buffer film (fourth buffer film) 12c formed on the buffer film 12b, as described above with reference to FIGS. 5 and 6 , and has the same effects as those of the stacked structure of the first embodiment. However, unlike the stacked structure of the first embodiment, the stacked structure of this modification has a (111) orientation in the pseudo-cubic crystal representation. Also, in the stacked structure of this modification, similar to the stacked structure of the first embodiment, when the metal film 14 contains Ir, the buffer film 12 preferably includes a buffer film 12d, and has the same effects as those of the stacked structure of the first embodiment. However, in the laminated structure of this modification, unlike the laminated structure of the first embodiment, the buffer film 12d has a (111) orientation in pseudo cubic crystal representation.

[0059] Second Embodiment Next, an electronic device according to a second embodiment of the present invention will be described. The electronic device according to the second embodiment is an inkjet printhead as a fluid discharge device, which includes the stacked structure 10 according to the first embodiment or a stacked structure 10a according to a modified example of the first embodiment. Figure 9 is a cross-sectional view of the electronic device according to the second embodiment.

[0060] As shown in FIG. 9, the electronic device 20 of the second embodiment includes a substrate 11 made of a Si substrate, a ZrO ２ , HZO or HfO ２ The electronic device includes a stacked structure 10 having a buffer film 12 made of Pt, a metal film 13 made of Pt, and a metal film 14, wherein the metal film 14 contains Fe, Cu, Mo, W, Ag, Al, Ti, or Ir as a main component.

[0061] The electronic device 20 of the second embodiment also includes a piezoelectric film 21 formed on the metal film 14, and a metal film 22 formed on the piezoelectric film 21. That is, the electronic device 20 of the second embodiment is a piezoelectric actuator in which the metal films 13 and 14 function as lower electrodes, and the metal film 22 functions as an upper electrode. The piezoelectric film 21 is made of, for example, aluminum nitride (AlN) or lead zirconate titanate (PZT). The metal film 22 is made of, for example, platinum (Pt).

[0062] The electronic device 20 of the second embodiment also includes a chamber 23 for storing a fluid. The chamber 23 is configured to take in the fluid from a tank (not shown) via a flow path 24.

[0063] A buffer film 12 is formed as a dielectric layer on a substrate 11 made of a Si substrate, and the buffer film 12 faces the chamber 23. As described above, the buffer film 12 made of HZO or the like is used as the dielectric layer, so that the SiO ２ Compared to the case where SiN or the like is used, the adhesiveness to the Si substrate and the crystallinity are excellent, and furthermore, the piezoelectric properties and durability are also excellent.

[0064] The electronic device 20 of the second embodiment further includes an insulating film 25 , a conductive path 26 , and a passivation film 27 .

[0065] The insulating film 25 is formed on the lower electrode made of the metal film 13 and the metal film 14, on the piezoelectric film 21, and on the upper electrode made of the metal film 22. The material for the insulating film 25 is not particularly limited, but examples of the material for the insulating film 25 include SiO. ２ , SiN or Al ２ O ３ The thickness of the insulating film 25 is not particularly limited, but is preferably between about 10 nm and about 10 μm.

[0066] The conductive path 26 is formed on the insulating film 25 and is electrically connected to the lower electrode made of the metal film 13 and the metal film 14, respectively, and the upper electrode made of the metal film 22, thereby enabling selective access when using the electronic device 20. Although the material constituting the conductive path 26 is not particularly limited, the material constituting the conductive path 26 may be a conductive material such as aluminum (Al).

[0067] The passivation film 27 is formed on the insulator film 25, on the lower electrode made of the metal film 13 and the metal film 14, on the upper electrode made of the metal film 22, and on the conductive path 26. The material constituting the passivation film 27 is not particularly limited, but a dielectric material such as SiN or SiON (silicon oxynitrate) can be used as the material constituting the passivation film 27. The thickness of the passivation film 27 is not particularly limited, but is preferably between about 0.1 μm and about 3 μm.

[0068] The electronic device 20 of the second embodiment has a conductive pad 28 made of a metal film 13a and a metal film 14a. The conductive pad 28 made of the metal film 13a and the metal film 14a is electrically connected to a conductive path 26, although not shown. The metal film 13a, together with the metal film 13, is epitaxially grown on the buffer film 12, is made of Pt, and has a (100) orientation in the cubic crystal representation. The metal film 14a, together with the metal film 14, is epitaxially grown on the metal film 13a, and contains iron (Fe), copper (Cu), molybdenum (Mo), tungsten (W), silver (Ag), aluminum (Al), titanium (Ti), or iridium (Ir) as a main component. An insulator film 25 is formed on the conductive pad 28 made of the metal film 13a and the metal film 14a.

[0069] According to the second embodiment, the metal film 14a containing Fe, Cu, Mo, W, Ag, Al, Ti, or Ir as a main component can be easily epitaxially grown on the metal film 13a, and thus the single-crystal metal film 14a can be easily formed on the substrate 11. Therefore, the electrical conductivity of the entire metal film 14a containing Fe, Cu, Mo, W, Cu, Ag, Al, Ti, or Ir as a main component can be improved, and the smoothness of the film surface can be improved. Therefore, the electrical characteristics of the piezoelectric actuator can be improved, for example, the power consumption of the piezoelectric actuator can be reduced.

[0070] As described above, the stacked structure 10 provided in the electronic device 20 of the second embodiment can also use an SOI substrate, which is a semiconductor substrate, instead of a Si substrate as the substrate 11, similarly to the stacked structure 10 of the first embodiment. Furthermore, the electronic device provided with the stacked structure is not limited to a piezoelectric actuator, and various electronic devices such as an FBAR (Film Bulk Acoustic Resonator) can be given as an example.

[0071] The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples.

[0072] Example 1 [Formation of Layered Structure] The layered structure of Example 1 was fabricated. First, the crystal growth surface of a Si substrate (100) was treated by reactive ion etching (RIE) and heated in the presence of oxygen to form a thermal oxide film. Then, without using oxygen, molecular beam epitaxy (MBE) was performed to thermally react metals (Hf, Zr) in the evaporation source with oxygen in the oxide film on the Si substrate, forming a single-crystal film of a first metal oxide on the Si substrate as buffer film 12 (see FIG. 1 ). Next, oxygen was introduced, the temperature was lowered, and the pressure was increased, and a single-crystal film of a first metal oxide was formed on the Si substrate as buffer film 12 (see FIG. 1 ). The MBE conditions for this film formation were as follows: The target value of Hf:Zr (atomic ratio, the same applies below) was 25:75 (x in the above composition formula (Chemical Formula 4) was 0.75). Vapor deposition source: Hf, Zr Voltage: 3.5 to 4.75 V Pressure: 3×10 －２ ~6 x 10 －２ Pa Substrate temperature: 450-700℃

[0073] Next, a platinum (Pt) metal film was formed as the metal film 13 by sputtering on the first metal oxide single crystal film as the buffer film 12. The conditions for this were as follows: Apparatus: ULVAC sputtering apparatus QAM-4 Pressure: 1.20×10 －１ Pa Target: Pt Power: 100 W (DC) Thickness: 100 nm Substrate temperature: 450 to 600°C

[0074] Next, a metal film 14 made of FeNiCr was formed on the metal film 13 by vapor deposition. In the process of forming the metal film 14 made of FeNiCr, Fe and Ni were first vapor deposited. The conditions for vapor depositing Fe and Ni are as follows: Vapor deposition source: Fe, Ni Pressure: 4×10 －４ Pa Substrate temperature: 100 to 500°C Film thickness: 100 nm

[0075] In the process of forming the metal film 14, Cr was then vapor-deposited on the top surface of the metal film 14 to form the metal film 14. The conditions for vapor-depositing Cr are as follows: Vapor deposition source: Cr Pressure: 4×10 －４ Pa Substrate temperature: 100 to 500°C Film thickness: 20 nm

[0076] In this manner, the metal film 14 made of FeNiCr was formed by vapor deposition on the buffer film 12 via the metal film 13, thereby producing the stacked structure of Example 1. As described above with reference to FIG. 3 , the metal film 13 may not be formed between the buffer film 12 and the metal film 14, and the metal film 14 may be formed on the buffer film 12 without the metal film 13 therebetween.

[0077] [X-ray Diffraction Measurement] After forming the buffer film 12 on the main surface 11p of the substrate 11, but before forming the metal film 13, the stacked structure was positioned so that the diffraction plane in the X-ray diffraction (XRD) measurement using the θ-2θ method was parallel to the main surface 11p, and the diffraction pattern of the stacked structure was measured by the X-ray diffraction measurement. The measured diffraction pattern of the stacked structure of Example 1 is shown in Figure 10. The X-ray diffraction measurement was performed using an X-ray diffractometer SmartLab manufactured by Rigaku Corporation.

[0078] As shown in FIG. 10, the diffraction pattern shows that tetragonal ZrO ２ (200) plane of HfO and monoclinic HfO ２ A strong diffraction peak of the (200) plane of HZO was observed, which revealed that the HZO contained in the first metal oxide was (100) oriented in the pseudocubic crystal representation.

[0079] Furthermore, with the stacked structure positioned so that the diffraction plane in the X-ray diffraction measurement was tilted at an angle of 45° with respect to the main surface 11p, a φ scan was performed on the (220) plane (2θ=50°) of HZO contained in the first metal oxide. The φ scan measured for the stacked structure of Example 1 is shown in FIG.

[0080] 11 , in the φ scan, four strong diffraction peaks of the (220) plane of HZO were observed at 90° intervals. That is, in the φ scan, diffraction peaks showing four-fold symmetry of HZO were observed. This revealed that the HZO contained in the first metal oxide has its crystal axis aligned in the in-plane direction along the main surface 11p of substrate 11, i.e., has grown epitaxially.

[0081] After forming the metal films 13 and 14, the obtained stacked structure of Example 1 was positioned so that the diffraction plane in X-ray diffraction measurement using the θ-2θ method was parallel to the main surface 11p, and the diffraction pattern of the stacked structure of Example 1 was measured by the X-ray diffraction measurement. The measured diffraction pattern of the stacked structure of Example 1 is shown in FIG.

[0082] 12, a strong diffraction peak of the (200) plane of Pt and a strong diffraction peak of the (200) plane of FeNiCr were observed in the diffraction pattern of Example 1. Therefore, it was revealed that in Example 1, Pt contained in metal film 13 was (200) oriented, and FeNiCr contained in metal film 14 was (200) oriented. In FIG. 12, the (200) plane of FeNiCr is denoted as Fe(200).

[0083] In addition, the stacked structure was positioned so that the diffraction plane in the X-ray diffraction measurement was inclined by 90° with respect to the main surface 11p (in-plane measurement), and a φ scan was performed on the Pt (200) plane (2θ=46°). The measured φ scan is shown in FIG.

[0084] 13, in the φ scan, four strong diffraction peaks of the (200) plane of Pt were observed at 90° intervals. That is, in the φ scan, diffraction peaks showing four-fold symmetry of Pt were observed. This revealed that the crystal axis of Pt contained in the metal film 13 was aligned in the in-plane direction along the main surface 11p of the substrate 11, i.e., epitaxial growth occurred.

[0085] In addition, the stacked structure was positioned so that the diffraction plane in the X-ray diffraction measurement was inclined at 45° with respect to the main surface 11p, and a φ scan was performed on the (110) plane (2θ=45°) of FeNiCr. The measured φ scan is shown in FIG.

[0086] 14, in the φ scan, four strong diffraction peaks of the (110) plane of FeNiCr were observed at 90° intervals. That is, in the φ scan, diffraction peaks showing four-fold symmetry of FeNiCr were observed. Therefore, it was revealed that the FeNiCr contained in the metal film 14 has its crystal axis aligned in the in-plane direction along the main surface 11p of the substrate 11, that is, it has grown epitaxially.

[0087] Although detailed description is omitted, even when the metal film 13 made of Pt is not formed between the buffer film 12 and the metal film 14, a strong diffraction peak of the (200) plane of FeNiCr is observed in the diffraction pattern obtained by X-ray diffraction measurement using the θ-2θ method, which reveals that the FeNiCr contained in the metal film 14 is (200) oriented. Furthermore, in a φ scan of the (110) plane of FeNiCr, a diffraction peak showing four-fold symmetry is observed, which reveals that the FeNiCr contained in the metal film 14 has grown epitaxially.

[0088] Furthermore, although detailed explanation is omitted, even when the ratio of Hf:Zr was other than 25:75 and x in the above composition formula (Chemical Formula 4) satisfied 0≦x<1 or x=1, the same results as in Example 1, in which the ratio of Hf:Zr was 25:75 (x in the above composition formula (Chemical Formula 4) was 0.75), were obtained.

[0089] (Example 2) [Formation of stacked structure] Next, a stacked structure of Example 2 was fabricated in exactly the same manner as in Example 1, except that a metal film 14 made of Cu was formed on the buffer film 12 (see FIG. 1) by vapor deposition.

[0090] In Example 2, similarly to Example 1, a buffer film 12 and a metal film 13 were formed, and then a metal film 14 made of Cu was formed on the metal film 13 by a vapor deposition method. In the step of forming this metal film 14 made of Cu, Cu was vapor-deposited. The conditions for vapor-depositing Cu are as follows: Vapor deposition source: Cu Pressure: 4×10 －４ Pa Substrate temperature: 100 to 500°C Film thickness: 120 nm

[0091] In this manner, the metal film 14 made of Cu was formed on the metal film 13 by vapor deposition, thereby producing the stacked structure of Example 2. As described above with reference to FIG. 3 , the metal film 13 may not be formed between the buffer film 12 and the metal film 14, and the metal film 14 may be formed on the buffer film 12 without the metal film 13 therebetween.

[0092] [X-ray Diffraction Measurement] After forming buffer film 12 on main surface 11p of substrate 11, but before forming metal film 13, the stacked structure was positioned so that the diffraction plane in X-ray diffraction measurement using the θ-2θ method was parallel to main surface 11p, and the diffraction pattern of the stacked structure was measured by the X-ray diffraction measurement. The measured diffraction pattern was similar to the result shown in FIG. 10 in Example 1, and it was revealed that HZO contained in the first metal oxide was (100)-oriented in pseudo cubic notation.

[0093] Furthermore, a φ scan was performed on the (220) plane (2θ=50°) of HZO contained in the first metal oxide. This φ scan yielded results similar to those shown in FIG. 11 in Example 1, revealing that the crystal axis of HZO contained in the first metal oxide is aligned in the in-plane direction along the main surface 11p of substrate 11, i.e., epitaxial growth has occurred.

[0094] After forming the metal films 13 and 14, the obtained stacked structure of Example 2 was measured for its diffraction pattern by X-ray diffraction measurement using the θ-2θ method, with the stacked structure being positioned so that the diffraction plane was parallel to the main surface 11p. The measured diffraction pattern of the stacked structure of Example 2 is shown in FIG.

[0095] 15 , a strong diffraction peak of the (200) plane of Pt and a strong diffraction peak of the (200) plane of Cu were observed in the measured diffraction pattern of Example 2. Therefore, it was revealed that in Example 2, Pt contained in metal film 13 was (200) oriented, and Cu contained in metal film 14 was (200) oriented.

[0096] Furthermore, a φ scan was performed on the (200) plane (2θ=46°) of the Pt contained in the metal film 13. The φ scan yielded results similar to those shown in FIG. 13 in Example 1, revealing that the crystal axis of the Pt contained in the metal film 13 is aligned in the in-plane direction along the main surface 11p of the substrate 11, i.e., epitaxial growth has occurred.

[0097] In addition, the stacked structure was positioned so that the diffraction plane in the X-ray diffraction measurement was inclined by 90° with respect to the main surface 11p (see FIG. 1), and a φ scan was performed on the Cu (200) plane (2θ=50°). The measured φ scan is shown in FIG.

[0098] 16, in the φ scan, four strong diffraction peaks of the (200) plane of Cu were observed at 90° intervals. That is, in the φ scan, diffraction peaks showing four-fold symmetry of Cu were observed. This revealed that the crystal axes of Cu contained in the metal film 14 were aligned in the in-plane direction along the main surface 11p of the substrate 11, i.e., epitaxial growth occurred.

[0099] Although detailed description is omitted, even when the metal film 13 made of Pt is not formed between the buffer film 12 and the metal film 14, a strong diffraction peak of the (200) plane of Cu is observed in the diffraction pattern obtained by X-ray diffraction measurement using the θ-2θ method, which reveals that the Cu contained in the metal film 14 is (200) oriented. Furthermore, in a φ scan of the Cu (200) plane, a diffraction peak showing four-fold symmetry is observed, which reveals that the Mo contained in the metal film 14 has grown epitaxially.

[0100] Although detailed explanation is omitted, when x in the above composition formula (Chemical Formula 4) satisfies 0≦x<1 or when x satisfies x=1, the same results as in Example 2 in which the ratio of Hf:Zr is 25:75 (x in the above composition formula (Chemical Formula 4) is 0.75) were obtained.

[0101] Example 3 [Formation of stacked structure] Next, a stacked structure of Example 3 was fabricated in exactly the same manner as in Example 1, except that a metal film 14 made of Mo was formed on the buffer film 12 by vapor deposition.

[0102] In Example 3, similarly to Example 1, a buffer film 12 was formed, and then a metal film 14 made of Mo was formed on the buffer film 12 by vapor deposition. In the process of forming the metal film 14 made of Mo, Mo was vapor-deposited. The conditions for vapor-depositing Mo are as follows: Vapor deposition source: Mo Pressure: 4×10 －４ Pa Substrate temperature: 100 to 500°C Film thickness: 120 nm

[0103] In this way, the metal film 14 made of Mo was formed on the metal film 13 by vapor deposition, thereby producing the stacked structure of Example 3. As described above with reference to FIG. 3 , the metal film 13 may not be formed between the buffer film 12 and the metal film 14, and the metal film 14 may be formed on the buffer film 12 without the metal film 13 therebetween.

[0104] [X-ray Diffraction Measurement] After forming buffer film 12 on main surface 11p of substrate 11, but before forming metal film 13, the stacked structure was positioned so that the diffraction plane in X-ray diffraction measurement using the θ-2θ method was parallel to main surface 11p, and the diffraction pattern of the stacked structure was measured by the X-ray diffraction measurement. The measured diffraction pattern was similar to the result shown in FIG. 10 in Example 1, and it was revealed that HZO contained in the first metal oxide was (100)-oriented in pseudo cubic notation.

[0105] Furthermore, a φ scan was performed on the (220) plane (2θ=50°) of HZO contained in the first metal oxide. This φ scan yielded results similar to those shown in FIG. 11 in Example 1, revealing that the crystal axis of HZO contained in the first metal oxide is aligned in the in-plane direction along the main surface 11p of substrate 11, i.e., epitaxial growth has occurred.

[0106] After forming the metal films 13 and 14, the obtained stacked structure of Example 3 was placed so that the diffraction plane in X-ray diffraction measurement using the θ-2θ method was parallel to the main surface 11p, and the diffraction pattern of the stacked structure of Example 3 was measured by the X-ray diffraction measurement. The measured diffraction pattern of the stacked structure of Example 3 is shown in FIG.

[0107] 17 , a strong diffraction peak of the (200) plane of Pt and a strong diffraction peak of the (110) plane of Mo were observed in the measured diffraction pattern of Example 3. Therefore, it was revealed that in Example 3, Pt contained in metal film 13 has a (200) orientation, and Mo contained in metal film 14 has a (110) orientation.

[0108] Furthermore, a φ scan was performed on the (200) plane (2θ=46°) of the Pt contained in the metal film 13. The φ scan yielded results similar to those shown in FIG. 13 in Example 1, revealing that the crystal axis of the Pt contained in the metal film 13 is aligned in the in-plane direction along the main surface 11p of the substrate 11, i.e., epitaxial growth has occurred.

[0109] In addition, the stacked structure was positioned so that the diffraction plane in the X-ray diffraction measurement was inclined at 45° with respect to the main surface 11p (see FIG. 1), and a φ scan was performed on the (200) plane (2θ=59°) of Mo. The measured φ scan is shown in FIG.

[0110] As shown in FIG. 18 , in the φ scan, four strong diffraction peaks of the Mo (200) plane were observed at 90° intervals. That is, in the φ scan, diffraction peaks showing apparent four-fold symmetry of Mo were observed. This revealed that the Mo contained in the metal film 14 has its crystal axes aligned in the in-plane direction along the main surface 11p of the substrate 11, i.e., epitaxial growth. If Mo were (110) oriented and composed of a single domain, two strong diffraction peaks of the Mo (200) plane would be expected to be observed at 180° intervals in the φ scan of the Mo (200) plane. On the other hand, the results shown in FIG. 18 indicate that the φ scan has two groups of diffraction peaks spaced 90° apart, each containing two diffraction peaks spaced 180° apart. Therefore, Mo is considered to have two types of domains: a first domain oriented in (110) and a second domain oriented in (110) and rotated 90° relative to the first domain within the principal plane.

[0111] Although detailed description is omitted, even when the metal film 13 made of Pt is not formed between the buffer film 12 and the metal film 14, a strong diffraction peak of the (110) plane of Mo is observed in the diffraction pattern obtained by X-ray diffraction measurement using the θ-2θ method, which reveals that the Mo contained in the metal film 14 is (110) oriented. Furthermore, four diffraction peaks are observed in a φ scan of the (200) plane of Mo, which reveals that the Mo contained in the metal film 14 has grown epitaxially.

[0112] Although detailed explanation is omitted, when x in the above composition formula (Chemical Formula 4) satisfies 0≦x<1 or satisfies x=1, the same results as in Example 3 in which the ratio of Hf:Zr is 25:75 (x in the above composition formula (Chemical Formula 4) is 0.75) were obtained.

[0113] Example 4 [Formation of stacked structure] Next, a stacked structure of Example 4 was fabricated in exactly the same manner as in Example 1, except that a metal film 14 made of W was formed on the buffer film 12 by vapor deposition.

[0114] In Example 4, similarly to Example 1, after forming the buffer film 12 and the metal film 13, a metal film 14 made of W was formed on the metal film 13 by a vapor deposition method. In the process of forming the metal film 14 made of W, W was vapor-deposited. The conditions for vapor-depositing W are as follows: Vapor deposition source: W Pressure: 4×10 －４ Pa Substrate temperature: 100 to 500°C Film thickness: 120 nm

[0115] In this way, the metal film 14 made of W was formed on the metal film 13 by vapor deposition, thereby producing the stacked structure of Example 4. As described above with reference to FIG. 3 , the metal film 13 may not be formed between the buffer film 12 and the metal film 14, and the metal film 14 may be formed on the buffer film 12 without the metal film 13 therebetween.

[0116] [X-ray Diffraction Measurement] After forming buffer film 12 on main surface 11p of substrate 11, but before forming metal film 13, the stacked structure was positioned so that the diffraction plane in X-ray diffraction measurement using the θ-2θ method was parallel to main surface 11p, and the diffraction pattern of the stacked structure was measured by the X-ray diffraction measurement. The measured diffraction pattern was similar to the result shown in FIG. 10 in Example 1, and it was revealed that HZO contained in the first metal oxide was (100)-oriented in pseudo cubic notation.

[0117] Furthermore, a φ scan was performed on the (220) plane (2θ=50°) of HZO contained in the first metal oxide. This φ scan yielded results similar to those shown in FIG. 11 in Example 1, revealing that the crystal axis of HZO contained in the first metal oxide is aligned in the in-plane direction along the main surface 11p of substrate 11, i.e., epitaxial growth has occurred.

[0118] After forming the metal films 13 and 14, the obtained stacked structure of Example 4 was placed so that the diffraction plane in X-ray diffraction measurement using the θ-2θ method was parallel to the main surface 11p, and the diffraction pattern of the stacked structure of Example 4 was measured by the X-ray diffraction measurement. The measured diffraction pattern of the stacked structure of Example 4 is shown in FIG.

[0119] 19 , a diffraction peak of the (200) plane of Pt and a strong diffraction peak of the (110) plane of W were observed in the measured diffraction pattern of Example 4. Therefore, it was revealed that in Example 4, Pt contained in metal film 13 has a (200) orientation, and W contained in metal film 14 has a (110) orientation.

[0120] Furthermore, a φ scan was performed on the (200) plane (2θ=46°) of the Pt contained in the metal film 13. The φ scan yielded results similar to those shown in FIG. 13 in Example 1, revealing that the crystal axis of the Pt contained in the metal film 13 is aligned in the in-plane direction along the main surface 11p of the substrate 11, i.e., epitaxial growth has occurred.

[0121] In addition, a φ scan was performed on the W (110) plane (2θ=40°) in a state where the stacked structure was positioned so that the diffraction plane in the X-ray diffraction measurement was inclined by 90° with respect to the main surface 11p (see FIG. 1) (in-plane measurement). The measured φ scan is shown in FIG.

[0122] As shown in FIG. 20 , four strong diffraction peaks of the W (110) plane were observed at 90° intervals in the φ scan. That is, diffraction peaks showing apparent four-fold symmetry of W were observed in the φ scan. This revealed that the W contained in the metal film 14 has its crystal axis aligned in the in-plane direction along the main surface 11p of the substrate 11, i.e., epitaxial growth. If the W is (110) oriented and consists of a single domain, two strong diffraction peaks of the W (110) plane are expected to be observed at 180° intervals in the φ scan of the W (110) plane. On the other hand, the results shown in FIG. 20 show that the φ scan has two groups of diffraction peaks spaced 90° apart, each containing two diffraction peaks spaced 180° apart. Therefore, W is considered to have two types of domains: a first domain oriented in (110) and a second domain oriented in (110) and rotated 90° relative to the first domain in the major plane.

[0123] Although detailed description is omitted, even when the metal film 13 made of Pt is not formed between the buffer film 12 and the metal film 14, a strong diffraction peak of the (110) plane of W is observed in the diffraction pattern obtained by X-ray diffraction measurement using the θ-2θ method, which reveals that the W contained in the metal film 14 has a (110) orientation. Furthermore, four diffraction peaks are observed in a φ scan of the (110) plane of W, which reveals that the W contained in the metal film 14 has grown epitaxially.

[0124] Although detailed explanation is omitted, when x in the above composition formula (Chemical Formula 4) satisfies 0≦x<1 or satisfies x=1, the same results as in Example 4, in which the ratio of Hf:Zr is 25:75 (x in the above composition formula (Chemical Formula 4) is 0.75), were obtained.

[0125] Although detailed explanation is omitted, when a metal film 14 made of Ti was formed instead of the metal film 14 made of W, the same results as when a metal film 14 made of W was formed were obtained.

[0126] Example 5 [Formation of stacked structure] Next, a stacked structure of Example 5 was fabricated in exactly the same manner as in Example 1, except that a metal film 14 made of Ag was formed on the buffer film 12 by vapor deposition.

[0127] In Example 5, after forming the buffer film 12 and the metal film 13, a metal film 14 made of Ag was formed on the metal film 13 by vapor deposition, unlike Example 1. The conditions for vapor deposition of Ag are as follows: Vapor deposition source: Ag Pressure: 4×10 －４ Pa Substrate temperature: 100 to 500°C Film thickness: 120 nm

[0128] As explained above with reference to FIG. 3, the metal film 13 may not be formed between the buffer film 12 and the metal film 14, and the metal film 14 may be formed on the buffer film 12 without the metal film 13 therebetween.

[0129] [X-ray Diffraction Measurement] After forming buffer film 12 on main surface 11p of substrate 11, but before forming metal film 13, a diffraction pattern was measured by X-ray diffraction measurement using the θ-2θ method, with the stacked structure positioned so that the diffraction plane in X-ray diffraction measurement was parallel to main surface 11p. The measured diffraction pattern was similar to the result shown in FIG. 10 in Example 1, and it was revealed that HZO contained in the first metal oxide was (100) oriented in pseudo cubic notation.

[0130] Furthermore, in a φ scan of the (220) plane (2θ=50°) of HZO contained in the first metal oxide, the same results as those shown in FIG. 11 in Example 1 were obtained, which revealed that the HZO contained in the first metal oxide has its crystal axis aligned in the in-plane direction along the main surface 11p of the substrate 11, i.e., has grown epitaxially.

[0131] After forming the metal films 13 and 14, the obtained stacked structure of Example 5 was placed so that the diffraction plane in X-ray diffraction measurement using the θ-2θ method was parallel to the main surface 11p, and the diffraction pattern of the stacked structure of Example 5 was measured by the X-ray diffraction measurement. The measured diffraction pattern of the stacked structure of Example 5 is shown in FIG.

[0132] 21 , a strong diffraction peak of the (200) plane of Pt and a strong diffraction peak of the (200) plane of Ag were observed in the measured diffraction pattern of Example 5. Therefore, it was revealed that in Example 5, Pt contained in metal film 13 was (200) oriented and Ag contained in metal film 14 was (100) oriented.

[0133] Furthermore, a φ scan was performed on the (200) plane (2θ=46°) of the Pt contained in the metal film 13. The φ scan yielded results similar to those shown in FIG. 13 in Example 1, revealing that the crystal axis of the Pt contained in the metal film 13 is aligned in the in-plane direction along the main surface 11p of the substrate 11, i.e., epitaxial growth has occurred.

[0134] In addition, the laminated structure was positioned so that the diffraction plane in the X-ray diffraction measurement was inclined at 45° with respect to the main surface 11p, and a φ scan was performed on the Ag (220) plane (2θ=64°). The measured φ scan is shown in FIG.

[0135] 22, in the φ scan, four strong diffraction peaks of the (220) plane of Ag were observed at 90° intervals. That is, in the φ scan, diffraction peaks showing four-fold symmetry of Ag were observed. This revealed that the Ag contained in the metal film 14 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.

[0136] Although detailed description is omitted, even when the metal film 13 made of Pt is not formed between the buffer film 12 and the metal film 14, a strong diffraction peak of the (200) plane of Ag is observed in the diffraction pattern obtained by X-ray diffraction measurement using the θ-2θ method, which reveals that the Ag contained in the metal film 14 is (100) oriented. Furthermore, in a φ scan of the (220) plane of Ag, a diffraction peak showing four-fold symmetry is observed, which reveals that the W contained in the metal film 14 is epitaxially grown.

[0137] Although detailed explanation is omitted, when x in the above composition formula (Chemical Formula 4) satisfies 0≦x<1 or satisfies x=1, the same results as in Example 5, in which the ratio of Hf:Zr is 25:75 (x in the above composition formula (Chemical Formula 4) is 0.75), were obtained.

[0138] Furthermore, although detailed explanation is omitted, when a metal film 14 made of Al was formed instead of the metal film 14 made of Ag, the same results as when a metal film 14 made of Ag was formed were obtained.

[0139] Example 6 [Formation of Layered Structure] Next, a metal film 14 made of Ir was formed on the buffer film 12 to fabricate a layered structure of Example 6.

[0140] First, the crystal growth surface side of the Si substrate (100) was treated by RIE and heated in the presence of oxygen to form a thermal oxide film. Then, without using oxygen, metals (Hf, Zr) from the evaporation source were thermally reacted with oxygen in the oxide film on the Si substrate by MBE to form a single crystal film of metal oxide as the buffer film 12 (see FIG. 1 ) on the Si substrate. Next, oxygen was introduced, the temperature was lowered, and the pressure was increased, and a single crystal film of metal oxide as the buffer film 12 (see FIG. 1 ) was formed by MBE. The MBE conditions for this film formation were as follows: The target Hf:Zr ratio was 25:75 (x in the above composition formula (Chemical Formula 4) was 0.75). In Example 6, Y and Al were added to HZO, and the target value of Hf:Zr:Y:Al (atomic ratio, the same applies below) was 23.75:71.25:2.5:2.5 (x, y, z in the above composition formula (Chemical Formula 5) were 0.7125, 0.025, 0.025). Vapor deposition source: Hf, Zr, Y, Al Voltage: 3.5 to 4.75 V Pressure: 3×10 －２ ~6 x 10 －２ Pa Substrate temperature: 450 to 700°C Thickness: 25 nm

[0141] Next, a platinum (Pt) metal film was formed as the metal film 13 by sputtering on the single crystal film of metal oxide as the buffer film 12. The conditions for this were as follows: Apparatus: ULVAC sputtering apparatus QAM-4 Pressure: 1.20×10 －１ Pa Target: Pt Power: 100 W (DC) Thickness: 5 nm Substrate temperature: 450 to 600°C

[0142] Next, a metal film 14 made of Ir was formed on the metal film 13 by vapor deposition under the following conditions: Vapor deposition source: Ir Pressure: 4×10 －４ Pa Substrate temperature: 550°C Film thickness: 20 nm

[0143] In this manner, the metal film 14 made of Ir was formed on the buffer film 12 via the metal film 13 by vapor deposition, thereby producing the stacked structure of Example 6. As described above with reference to FIG. 3 , the metal film 13 may not be formed between the buffer film 12 and the metal film 14, and the metal film 14 may be formed on the buffer film 12 without the metal film 13 interposed therebetween. However, by forming the metal film 13 between the buffer film 12 and the metal film 14, the metal film 14 can be easily epitaxially grown on the buffer film 12.

[0144] [X-ray Diffraction Measurement] After forming the buffer film 12 on the main surface 11p of the substrate 11, and before forming the metal film 13, the stacked structure was positioned so that the diffraction plane in the X-ray diffraction measurement using the θ-2θ method was parallel to the main surface 11p, and the diffraction pattern of the stacked structure was measured by the X-ray diffraction measurement. The measured diffraction pattern was similar to the result shown in FIG. 10 in Example 1, and it was revealed that the HZO contained in the metal oxide was (100) oriented in pseudo cubic crystal representation.

[0145] Furthermore, a φ scan was performed on the (220) plane (2θ=50°) of HZO contained in the metal oxide. The φ scan yielded results similar to those shown in FIG. 11 in Example 1, revealing that the crystal axis of HZO contained in the metal oxide is aligned in the in-plane direction along the main surface 11p of the substrate 11, i.e., epitaxial growth has occurred.

[0146] After forming the metal films 13 and 14, the obtained stacked structure of Example 6 was placed so that the diffraction plane in X-ray diffraction measurement using the θ-2θ method was parallel to the main surface 11p, and the diffraction pattern of the stacked structure of Example 6 was measured by the X-ray diffraction measurement. The measured diffraction pattern of the stacked structure of Example 6 is shown in FIG.

[0147] As shown in FIG. 23 , in the measured diffraction pattern of Example 6, strong diffraction peaks of the tetragonal (002) plane of HZO (HZO t(002)), the tetragonal (004) plane of HZO (HZO t(004)), the cubic (200) plane of Pt (Pt(002)), the cubic (400) plane of Pt (Pt(004)), and the cubic (200) plane of Ir (Ir(002)) and the cubic (400) plane of Ir (Ir(004)) were observed. Therefore, in Example 6, it was revealed that the HZO contained in the buffer film 12 has a (100) orientation in pseudo-cubic notation, the Pt contained in the metal film 13 has a cubic crystal structure and is (100) oriented, and the Ir contained in the metal film 14 has a cubic crystal structure and is (100) oriented.

[0148] After forming the metal films 13 and 14, the obtained stacked structure of Example 6 was placed so that the diffraction plane in X-ray diffraction measurement using the θ-2θ method was inclined by 90° with respect to the main surface 11p (in-plane measurement), and the diffraction pattern of the metal film 14, which was the uppermost layer of the stacked structure of Example 6, was measured by the X-ray diffraction measurement. The measured diffraction pattern of the stacked structure of Example 6 is shown in FIG.

[0149] 24 , a strong diffraction peak (Ir(200)) of the cubic (200) plane of Ir and a strong diffraction peak (Ir(400)) of the cubic (400) plane of Ir were observed in the diffraction pattern (in-plane measurement) of Example 6. This revealed that the crystal axes of Ir contained in metal film 14 were aligned in the in-plane direction along main surface 11p of substrate 11, i.e., epitaxial growth occurred.

[0150] 24 (in-plane measurement), a φ scan was then performed on the cubic (200) plane (2θ=47°) of Ir contained in the metal film 14 in a state (in-plane measurement) in which the stacked structure was positioned so that the diffraction plane in the X-ray diffraction measurement was inclined by 90° with respect to the main surface 11p. The φ scan measured for the metal film 14 of the stacked structure of Example 6 is shown in FIG.

[0151] As shown in the graph of Fig. 25, in the φ scan, four strong diffraction peaks of the cubic (200) plane of Ir contained in the metal film 14 were observed at 90° intervals. That is, in the φ scan, diffraction peaks showing four-fold symmetry of the Ir contained in the metal film 14 were observed. Therefore, as in Fig. 24, Fig. 25 also reveals that the crystal axes of the Ir contained in the metal film 14 are aligned in the in-plane direction along the main surface 11p of the substrate 11, that is, epitaxial growth has occurred.

[0152] Although detailed description will be omitted, even when the metal film 13 made of Pt is not formed between the buffer film 12 and the metal film 14, a strong diffraction peak of the cubic (200) plane of Ir and a strong diffraction peak of the cubic (400) plane of Ir are observed in the diffraction pattern obtained by X-ray diffraction measurement using the θ-2θ method, revealing that the Ir contained in the metal film 14 has a cubic crystal structure and is (100) oriented. Furthermore, a diffraction peak showing four-fold symmetry is observed in a φ scan of the cubic (200) plane of Ir, revealing that the Ir contained in the metal film 14 has grown epitaxially. However, when the metal film 13 is formed between the buffer film 12 and the metal film 14, the intensity of the diffraction peak showing four-fold symmetry is increased in a φ scan of the cubic (200) plane of Ir compared to when the metal film 13 is not formed between the buffer film 12 and the metal film 14, revealing that the metal film 14 can be easily epitaxially grown on the buffer film 12.

[0153] Furthermore, although detailed explanation is omitted, when the buffer film 12 is made of a metal oxide represented by the above composition formula (Chemical Formula 5), ​​even when x in the above composition formula (Chemical Formula 5) satisfies 0≦x<1, y in the above composition formula (Chemical Formula 5) satisfies 0<y≦0.3, and z in the above composition formula (Chemical Formula 5) satisfies 0<z≦0.3, the same results as in Example 6, in which the ratio of Hf:Zr:Y:Al is 23.75:71.25:2.5:2.5 (x, y, z in the above composition formula (Chemical Formula 5) are 0.7125, 0.025, 0.025), were obtained.

[0154] Furthermore, although detailed explanation is omitted, when the buffer film 12 does not contain Y and Al, i.e., when the buffer film 12 is made of the first metal oxide represented by the above composition formula (Chemical Formula 4), results similar to those when the Hf:Zr ratio is 25:75 (x in the above composition formula (Chemical Formula 4) is 0.75) were obtained even when x in the above composition formula (Chemical Formula 4) satisfies 0≦x<1 or when x = 1. However, when the buffer film 12 contains Y and Al, it became clear that the metal film 14 can be easily epitaxially grown on the buffer film 12, for example, the intensity of the diffraction peak showing four-fold symmetry is increased in a φ scan of the cubic (200) plane of Ir compared to when the buffer film 12 does not contain Y and Al.

[0155] (Example 7) [Formation of stacked structure] Next, the stacked structure of Example 7 was fabricated in exactly the same manner as in Example 6, except that the metal film 14 made of Ir was formed on the buffer film 12 at 400°C instead of 550°C.

[0156] [X-ray Diffraction Measurement] In the stacked structure of Example 7, as in the stacked structure of Example 6, it was revealed that the HZO contained in the metal oxide contained in the buffer film 12 has a (100) orientation in pseudo-cubic crystal representation and has grown epitaxially.

[0157] After forming the metal films 13 and 14, the obtained stacked structure of Example 7 was placed so that the diffraction plane in X-ray diffraction measurement using the θ-2θ method was parallel to the main surface 11p, and the diffraction pattern of the stacked structure of Example 7 was measured by the X-ray diffraction measurement. The measured diffraction pattern of the stacked structure of Example 7 is shown in FIG.

[0158] As shown in FIG. 26 , in the measured diffraction pattern of Example 7, strong diffraction peaks of the monoclinic (002) plane of HZO (HZO m(002)), the monoclinic (004) plane of HZO (HZO m(004)), the cubic (200) plane of Pt (Pt(002)), the cubic (400) plane of Pt (Pt(004)), and the cubic (200) plane of Ir (Ir(002)) and the cubic (400) plane of Ir (Ir(004)) were observed. Therefore, in Example 7 as well, similarly to Example 6, it was revealed that the HZO contained in the buffer film 12 has a (100) orientation in the pseudo-cubic crystal notation, the Pt contained in the metal film 13 has a cubic crystal structure and is (100) oriented, and the Ir contained in the metal film 14 has a cubic crystal structure and is (100) oriented.

[0159] After forming the metal films 13 and 14, the obtained stacked structure of Example 7 was placed so that the diffraction plane in X-ray diffraction measurement using the θ-2θ method was inclined by 90° with respect to the main surface 11p (in-plane measurement), and the diffraction pattern of the metal film 14, which was the uppermost layer of the stacked structure of Example 7, was measured by the X-ray diffraction measurement. The measured diffraction pattern of the stacked structure of Example 7 is shown in FIG.

[0160] 27 , in the diffraction pattern (in-plane measurement) of Example 7, a strong diffraction peak (Ir(200)) of the cubic (200) plane of Ir and a strong diffraction peak (Ir(400)) of the cubic (400) plane of Ir were observed. This revealed that the crystal axes of Ir contained in metal film 14 were aligned in the in-plane direction along main surface 11p of substrate 11, i.e., epitaxial growth occurred.

[0161] 27 (in-plane measurement), a φ scan was then performed on the cubic (200) plane (2θ=47°) of Ir contained in the metal film 14 in a state (in-plane measurement) in which the stacked structure was positioned so that the diffraction plane in the X-ray diffraction measurement was inclined by 90° with respect to the main surface 11p. The φ scan measured for the metal film 14 of the stacked structure of Example 7 is shown in FIG.

[0162] As shown in the graph of Fig. 28, in the φ scan, four strong diffraction peaks of the cubic (200) plane of Ir contained in the metal film 14 were observed at 90° intervals. That is, in the φ scan, diffraction peaks showing four-fold symmetry of the Ir contained in the metal film 14 were observed. Therefore, as in Fig. 27, Fig. 28 also reveals that the crystal axes of the Ir contained in the metal film 14 are aligned in the in-plane direction along the main surface 11p of the substrate 11, that is, epitaxial growth has occurred.

[0163] Although detailed description will be omitted, even when the metal film 13 made of Pt is not formed between the buffer film 12 and the metal film 14, a strong diffraction peak of the cubic (200) plane of Ir and a strong diffraction peak of the cubic (400) plane of Ir are observed in the diffraction pattern obtained by X-ray diffraction measurement using the θ-2θ method, revealing that the Ir contained in the metal film 14 has a cubic crystal structure and is (100) oriented. Furthermore, a diffraction peak showing four-fold symmetry is observed in a φ scan of the cubic (200) plane of Ir, revealing that the Ir contained in the metal film 14 has grown epitaxially. However, when the metal film 13 is formed between the buffer film 12 and the metal film 14, the intensity of the diffraction peak showing four-fold symmetry is increased in a φ scan of the cubic (200) plane of Ir compared to when the metal film 13 is not formed between the buffer film 12 and the metal film 14, revealing that the metal film 14 can be easily epitaxially grown on the buffer film 12.

[0164] Furthermore, although detailed explanation is omitted, when the buffer film 12 is made of a metal oxide represented by the above composition formula (Chemical Formula 5), ​​even when x in the above composition formula (Chemical Formula 5) satisfies 0≦x<1, y in the above composition formula (Chemical Formula 5) satisfies 0<y≦0.3, and z in the above composition formula (Chemical Formula 5) satisfies 0<z≦0.3, the same results as in Example 7, in which the ratio of Hf:Zr:Y:Al is 23.75:71.25:2.5:2.5 (x, y, z in the above composition formula (Chemical Formula 5) are 0.7125, 0.025, 0.025), were obtained.

[0165] Furthermore, although detailed explanation is omitted, when the buffer film 12 does not contain Y and Al, i.e., when the buffer film 12 is made of the first metal oxide represented by the above composition formula (Chemical Formula 4), results similar to those when the Hf:Zr ratio is 25:75 (x in the above composition formula (Chemical Formula 4) is 0.75) were obtained even when x in the above composition formula (Chemical Formula 4) satisfies 0≦x<1 or when x = 1. However, when the buffer film 12 contains Y and Al, it became clear that the metal film 14 can be easily epitaxially grown on the buffer film 12, for example, the intensity of the diffraction peak showing four-fold symmetry is increased in a φ scan of the cubic (200) plane of Ir compared to when the buffer film 12 does not contain Y and Al.

[0166] Example 8 [Formation of Layered Structure] Next, a layered structure of Example 8 was fabricated in the same manner as in Example 6, except that a Si(111) substrate was used as the substrate 11 instead of the Si(100) substrate.

[0167] [X-ray Diffraction Measurement] After forming the buffer film 12, the metal film 13, and the metal film 14 on the main surface 11p of the substrate 11, the stacked structure was positioned so that the diffraction plane in the X-ray diffraction measurement using the θ-2θ method was parallel to the main surface 11p, and the diffraction pattern of the stacked structure was measured by the X-ray diffraction measurement. The measured diffraction pattern of the stacked structure of Example 8 is shown in Figure 29.

[0168] 29 , in the measured diffraction pattern of Example 8, a strong diffraction peak of the monoclinic (111) plane of HZO (HZO m(111)), a strong diffraction peak of the cubic (111) plane of Pt (Pt(111)), and a strong diffraction peak of the cubic (111) plane of Ir (Ir(111)) were observed. Therefore, it was revealed that in Example 8, HZO contained in buffer film 12 has a (111) orientation in pseudo-cubic notation, Pt contained in metal film 13 has a cubic crystal structure and is (111) oriented, and Ir contained in metal film 14 has a cubic crystal structure and is (111) oriented.

[0169] After forming the metal films 13 and 14, the obtained stacked structure of Example 8 was placed so that the diffraction plane in the X-ray diffraction measurement using the θ-2θ method was inclined by 90° with respect to the main surface 11p (in-plane measurement), and the diffraction pattern of the metal film 14, which was the uppermost layer of the stacked structure of Example 8, was measured by the X-ray diffraction measurement. The measured diffraction pattern of the stacked structure of Example 8 is shown in FIG.

[0170] 30 , a strong diffraction peak (Ir(220)) of the cubic (220) plane of Ir was observed in the diffraction pattern (in-plane measurement) of Example 8. This revealed that the crystal axis of Ir contained in metal film 14 was aligned in the in-plane direction along main surface 11p of substrate 11, i.e., epitaxial growth occurred.

[0171] 30 (in-plane measurement), the stacked structure was positioned so that the diffraction plane in the X-ray diffraction measurement was inclined by 90° with respect to the main surface 11p (in-plane measurement), and a φ scan was then performed on the cubic (220) plane (2θ=69°) of Ir contained in the metal film 14. The φ scan measured for the metal film 14 of the stacked structure of Example 8 is shown in FIG.

[0172] As shown in the graph of FIG. 31 , in the φ scan, six strong diffraction peaks of the cubic (220) plane of Ir contained in the metal film 14 were observed at 60° intervals. That is, in the φ scan, diffraction peaks showing six-fold symmetry of Ir contained in the metal film 14 were observed. This means that the metal film 14, which is made of Ir and has a cubic crystal structure and a (111) orientation, consists of two domains, each of which has three-fold symmetry in a plan view, and one of which is rotated 60° relative to the other. Therefore, as in FIG. 30 , FIG. 31 also reveals that the crystal axes of Ir contained in the metal film 14 are aligned in the in-plane direction along the main surface 11p of the substrate 11, i.e., epitaxial growth has occurred.

[0173] Although detailed description will be omitted, even when the metal film 13 made of Pt is not formed between the buffer film 12 and the metal film 14, a strong diffraction peak of the cubic (111) plane of Ir is observed in the diffraction pattern obtained by X-ray diffraction measurement using the θ-2θ method, revealing that the Ir contained in the metal film 14 has a cubic crystal structure and is (111) oriented. Furthermore, a diffraction peak showing 6-fold symmetry is observed in a φ scan of the cubic (220) plane of Ir, revealing that the Ir contained in the metal film 14 has grown epitaxially. However, when the metal film 13 is formed between the buffer film 12 and the metal film 14, the intensity of the diffraction peak showing 6-fold symmetry is increased in a φ scan of the cubic (220) plane of Ir compared to when the metal film 13 is not formed between the buffer film 12 and the metal film 14, revealing that the metal film 14 can be easily epitaxially grown on the buffer film 12.

[0174] Furthermore, although detailed explanation is omitted, when the buffer film 12 is made of a metal oxide represented by the above composition formula (Chemical Formula 5), ​​even when x in the above composition formula (Chemical Formula 5) satisfies 0≦x<1, y in the above composition formula (Chemical Formula 5) satisfies 0<y≦0.3, and z in the above composition formula (Chemical Formula 5) satisfies 0<z≦0.3, the same results as in Example 8, in which the ratio of Hf:Zr:Y:Al is 23.75:71.25:2.5:2.5 (x, y, z in the above composition formula (Chemical Formula 5) are 0.7125, 0.025, 0.025), were obtained.

[0175] Furthermore, although detailed explanation is omitted, when the buffer film 12 does not contain Y and Al, i.e., when the buffer film 12 is made of the first metal oxide represented by the above composition formula (Chemical Formula 4), results similar to those when the Hf:Zr ratio is 25:75 (x in the above composition formula (Chemical Formula 4) is 0.75) were obtained even when x in the above composition formula (Chemical Formula 4) satisfies 0≦x<1 or when x satisfies x=1. However, when the buffer film 12 contains Y and Al, it became clear that the metal film 14 can be easily epitaxially grown on the buffer film 12, for example, the intensity of the diffraction peak showing 6-fold symmetry in a φ scan of the cubic (220) plane of Ir is greater than when the buffer film 12 does not contain Y and Al.

[0176] Example 9 [Formation of stacked structure] Next, instead of the buffer film 12 made of a metal oxide containing Hf, Zr, Y, and Al, a buffer film 12a (see FIG. 6) made of a second metal oxide containing YSZ, and a third metal oxide (YAlO) formed on the buffer film 12a and containing Y and Al were formed. ３ a buffer film 12b (see FIG. 6) made of CeO, which is a fourth metal oxide containing Ce and formed on the buffer film 12b; ２ The stacked structure of Example 9 was fabricated in the same manner as in Example 6, except that a buffer film 12 including a buffer film 12c (see FIG. 6) made of the metal film 13 was formed. The thickness of the buffer film 12a was 5 nm, the thickness of the buffer film 12b was 20 nm, the thickness of the buffer film 12c was 2.5 nm, the thickness of the metal film 13 was 5 nm, and the thickness of the metal film 14 was 20 nm.

[0177] [X-ray Diffraction Measurement] After forming the buffer film 12, the metal film 13, and the metal film 14 on the main surface 11p of the substrate 11, the stacked structure was positioned so that the diffraction plane in the X-ray diffraction measurement using the θ-2θ method was parallel to the main surface 11p, and the diffraction pattern of the stacked structure was measured by the X-ray diffraction measurement. The measured diffraction pattern of the stacked structure of Example 9 is shown in Figure 32.

[0178] As shown in FIG. 32, in the measured diffraction pattern of Example 9, YAlO ３ In the pseudocubic crystal representation, there are strong diffraction peaks on the (200) plane (YAO (200)) and YAlO ３ In the pseudo cubic crystal representation, a strong diffraction peak of the (400) plane (YAO(400)), a strong diffraction peak of the cubic (200) plane of Pt (Pt(200)), and a strong diffraction peak of the cubic (200) plane of Ir (Ir(200)) were observed. ３ It was revealed that Pt contained in metal film 13 has a cubic crystal structure and is oriented in the (100) direction in the pseudo-cubic crystal representation, Pt contained in metal film 13 has a cubic crystal structure and is oriented in the (100) direction, and Ir contained in metal film 14 has a cubic crystal structure and is oriented in the (100) direction.

[0179] After forming the metal films 13 and 14, the stacked structure was positioned so that the diffraction plane in the X-ray diffraction measurement was inclined at 90° with respect to the main surface 11p (in-plane measurement), and a φ scan was performed on the cubic (220) plane (2θ=69°) of Ir contained in the metal film 14. The φ scan measured for the metal film 14 of the stacked structure of Example 9 is shown in FIG.

[0180] 33, in the φ scan, four strong diffraction peaks of the cubic (220) plane of Ir contained in the metal film 14 were observed at 90° intervals. That is, in the φ scan, diffraction peaks showing four-fold symmetry of Ir contained in the metal film 14 were observed. This revealed that the crystal axes of Ir contained in the metal film 14 were aligned in the in-plane direction along the main surface 11p of the substrate 11, i.e., epitaxial growth occurred.

[0181] Although detailed description is omitted, YAlO ３ and a metal film 14 made of Ir. ２ Even when the buffer film 12c made of Pt or the metal film 13 made of Pt was not formed, a strong diffraction peak of the cubic (200) plane of Ir was observed in the diffraction pattern obtained by X-ray diffraction measurement using the θ-2θ method, and it was revealed that the Ir contained in the metal film 14 has a cubic crystal structure and is (100) oriented. However, it was found that when the buffer film 12c and the metal film 13 are formed between the buffer film 12b and the metal film 14, the growth rate of the metal film 14 can be significantly improved compared to the growth rate of the metal film 14 when the buffer film 12c or the metal film 13 is not formed between the buffer film 12b and the metal film 14.

[0182] Furthermore, although detailed explanation is omitted, even when a buffer film 12a made of a second metal oxide containing YSH was used instead of YSZ as the buffer film 12a, the same results as those of Example 9, in which a buffer film 12a made of a second metal oxide containing YSZ was used as the buffer film 12a, were obtained.

[0183] 10, 10a Laminated structure 11 Substrate 11a Base body 11b Insulating layer 11c SOI layer 11p Main surface 12, 12a to 12d Buffer film 13, 13a, 14, 14a, 22 Metal film 20 Electronic device 21 Piezoelectric film 23 Chamber 24 Flow path 25 Insulating film 26 Conductive path 27 Passivation film 28 Conductive pad

Claims

1. A laminated structure having a substrate including a main surface, a first buffer film formed on the main surface, and a first metal film formed on the first buffer film, wherein the substrate is a Si substrate or an SOI substrate including a base body made of a Si substrate, an insulating layer on the base body, and an SOI layer on the insulating layer, and the first buffer film is made of a first metal oxide represented by the following composition formula (Chemical Formula 1): (Hf １－ｘ Zr ｘ ) O ２ a first metal film containing Fe, Cu, Mo, W, Ag, Al, Ti, or Ir as a main component; 2. The stacked structure according to claim 1, further comprising a second metal film formed on the first buffer film, the first metal film being formed on the second metal film, and the second metal film being made of Pt.

3. The stacked structure according to claim 2, wherein the first buffer film is made of the first metal oxide epitaxially grown on the main surface, the second metal film is made of Pt epitaxially grown on the first buffer film, and the first metal film is epitaxially grown on the second metal film.

4. The stacked structure according to claim 2, wherein the substrate is a Si(100) substrate having a main surface formed of a Si(100) plane, or an SOI substrate including a base body formed of a Si substrate, an insulating layer on the base body, and an SOI layer formed of a Si(100) film on the insulating layer and having a main surface formed of a Si(100) plane, the first buffer film is made of the first metal oxide having a (100) orientation in pseudo-cubic notation, and the second metal film has a cubic crystal structure and is (100) oriented.

5. The laminated structure according to claim 4, wherein the first metal film contains Fe, has a cubic crystal structure, and is (100) oriented.

6. The laminated structure according to claim 5, wherein the first metal film contains Cr or Ni.

7. The laminated structure according to claim 4, wherein the first metal film contains Cu, has a cubic crystal structure, and is (100) oriented.

8. The laminated structure according to claim 4, wherein the first metal film contains Mo, has a cubic crystal structure, and is (110) oriented.

9. The laminated structure according to claim 4, wherein the first metal film contains W, has a cubic crystal structure, and is (110) oriented.

10. The laminated structure according to claim 4, wherein the first metal film contains Ag, has a cubic crystal structure, and is (100) oriented.

11. The laminated structure according to claim 4, wherein the first metal film contains Al, has a cubic crystal structure, and is (100) oriented.

12. The laminated structure according to claim 4, wherein the first metal film contains Ti, has a cubic crystal structure, and is (110) oriented.

13. The stacked structure according to claim 4, wherein the first metal film contains Ir, has a cubic crystal structure, and is (100) oriented.

14. The stacked structure according to claim 2, wherein the substrate is a Si(111) substrate having a main surface formed of a Si(111) plane, or an SOI substrate including a base formed of a Si substrate, an insulating layer on the base, and an SOI layer formed of a Si(111) film on the insulating layer and having a main surface formed of a Si(111) plane, the first buffer film is made of the first metal oxide having a (111) orientation in pseudo-cubic notation, and the second metal film has a cubic crystal structure and is (111) oriented.

15. The stacked structure according to claim 14, wherein the first metal film contains Ir, has a cubic crystal structure, and is (111) oriented.

16. The first buffer film includes a second buffer film formed on the main surface, a third buffer film formed on the second buffer film, and a fourth buffer film formed on the third buffer film, and the second buffer film is made of a second metal oxide represented by the following composition formula (Chemical Formula 2): (Hf １－ｘ１－ｙ１ Zr ｘ１ M ｙ１ ) O ２－ｚ１ ... (Chemical Formula 2) (wherein, in the composition formula (Chemical Formula 2), M is at least one selected from the group consisting of Nb, Ta, Si, Ti, rare earth elements, Al, and Group 2 elements). The y1 satisfies 0<y1≦0.3, and the x1 satisfies 0≦x1≦1−y1. The third buffer film is made of a third metal oxide represented by the following composition formula (Chemical Formula 3), (RE ｘ２ Al ｙ２ ) O ｚ２ ... (Chemical Formula 3) (In the composition formula (Chemical Formula 3), RE is one or more elements selected from the group consisting of rare earth elements. ） 　 16. The stacked structure according to claim 13, wherein the fourth buffer film is made of a fourth metal oxide containing Ce.

17. An electronic device comprising the laminate structure according to any one of claims 1 to 3.

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