Membrane structure and manufacturing method thereof

Abstract

To provide a film structure having a buffer film formed on a substrate and being capable of aligning an alignment direction of a metal film or a piezoelectric film formed on the buffer film in a fixed direction.SOLUTION: A film structure 10 includes a substrate 11 and a buffer film 12 formed on the substrate 11. The substrate 11 is an SOI substrate containing a rotating Y-cut Si substrate of 36°-48° or a base composed of the rotating Y-cut Si substrate of 36°-48°, an insulation layer on the base, and an SOI layer composed of an Si film on the insulation layer. A Miller index of a crystal plane on an upper surface of the SOI layer is the same as that of the crystal plane on the upper surface of the base. The buffer film 12 includes ZrO2 epitaxially grown on the substrate 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a membrane structure and a method for manufacturing the same. [Background technology]

[0002] As a film structure having a substrate, a buffer film formed on the substrate, and a metal film formed on the buffer film, a film structure having a silicon (Si) substrate, a buffer film containing zirconium oxide (ZrO2) formed on the Si substrate, and a metal film containing platinum (Pt) formed on the buffer film is known. Also known is a film structure having a piezoelectric film formed on the metal film.

[0003] Japanese Patent Application Laid-Open Publication No. 2018-81974 (Patent Document 1) discloses a technology for a film structure having a substrate including a base, an insulating layer on the base, and a silicon layer on the insulating layer, a first film including zirconium oxide epitaxially grown on the silicon layer, a first conductive film including platinum epitaxially grown on the first film, and a piezoelectric film epitaxially grown on the first conductive film.

[0004] Japanese Patent Application Laid-Open Publication No. 2018-81975 (Patent Document 2) discloses a technology in which a film structure has a silicon substrate, a first film containing zirconium formed on the silicon substrate, a second film containing zirconium oxide epitaxially grown on the first film, a first conductive film containing platinum epitaxially grown on the second film, and a piezoelectric film epitaxially grown on the first conductive film. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-81974 [Patent Document 2] Japanese Patent Application Publication No. 2018-81975 Summary of the Invention [Problem to be solved by the invention]

[0006] In the techniques described in Patent Documents 1 and 2, the film structure includes a buffer film containing ZrO formed on a silicon layer or a silicon substrate, and a metal film containing Pt formed on the buffer film. However, depending on the type of silicon layer or silicon substrate, or the type of buffer film, it can be difficult to align the orientation of the metal film formed on the buffer film in a uniform direction. In such cases, when a piezoelectric film is further formed on the metal film, it can also be difficult to align the orientation of the piezoelectric film formed on the metal film in a uniform direction.

[0007] The present invention has been made to solve the problems of the conventional technology as described above, and aims to provide a film structure having a buffer film formed on a substrate, in which the orientation direction of a metal film or piezoelectric film formed on the buffer film can be aligned in a fixed direction. [Means for solving the problem]

[0008] Among the inventions disclosed in this application, the outline of representative inventions will be briefly explained as follows.

[0009] A film structure according to one embodiment of the present invention includes a substrate and a buffer film formed on the substrate. The substrate is a 36° to 48° rotated Y-cut Si substrate, or an SOI substrate including a base body made of the 36° to 48° rotated Y-cut Si substrate, an insulating layer on the base body, and an SOI layer made of a Si film on the insulating layer, and the Miller indices of the crystal plane of the upper surface of the SOI layer are the same as those of the crystal plane of the upper surface of the base. The buffer film includes ZrO2 epitaxially grown on the substrate.

[0010] In another embodiment, the film structure may have a metal film epitaxially grown on the buffer film.

[0011] In another embodiment, the metal film may contain Pt.

[0012] In another embodiment, the film structure may have an SRO film epitaxially grown on a metal film.

[0013] In another embodiment, the film structure may have a piezoelectric film epitaxially grown on a metal film.

[0014] In another embodiment, the film structure may have a piezoelectric film epitaxially grown on an SRO film.

[0015] In another embodiment, two diffraction peaks each representing the SRO(110) plane of the SRO film may be observed in the in-plane X-ray diffraction pattern of the film structure.

[0016] In another embodiment, the film structure may have a piezoelectric film epitaxially grown on a buffer film.

[0017] In another embodiment, the piezoelectric film may include PZT, AlN, LiTaO3, or LiNbO3.

[0018] In another embodiment, the piezoelectric film is a PZT film containing PZT, and two diffraction peaks each representing the PZT (213) plane of the PZT film may be observed in the in-plane X-ray diffraction pattern of the film structure.

[0019] In another embodiment, in X-ray reciprocal lattice space mapping of the film structure, three reciprocal lattice points respectively representing the PZT(110) plane of the PZT film, the Si(220) plane of the substrate, and the PZT(112) plane of the PZT film may be arranged in the Qz direction.

[0020] A method for manufacturing a film structure according to one aspect of the present invention includes the steps of (a) preparing a substrate and (b) forming a buffer film on the substrate. In the step (a), an SOI substrate is prepared, which includes a base made of a 36° to 48° rotated Y-cut substrate or a 36° to 48° rotated Y-cut Si substrate, an insulating layer on the base, and an SOI layer made of a Si film on the insulating layer, and the Miller indices of the crystal plane of the upper surface of the SOI layer are the same as those of the crystal plane of the upper surface of the substrate. In the step (b), a buffer film containing epitaxially grown ZrO2 is formed on the substrate.

[0021] In another embodiment, the method for manufacturing the film structure includes a step (c) of forming an epitaxially grown metal film on the buffer film, and the metal film may contain Pt.

[0022] In another aspect, the method for manufacturing the film structure may include a step (d) of forming an epitaxially grown SRO film on a metal film, and two diffraction peaks each representing an SRO(110) plane of the SRO film may be observed in an in-plane X-ray diffraction pattern of the film structure.

[0023] In another aspect, the method for manufacturing the film structure includes the step (e) of forming an epitaxially grown piezoelectric film on the metal film, and the piezoelectric film may include PZT, AlN, LiTaO3, or LiNbO3. [Effects of the Invention]

[0024] By applying one aspect of the present invention, in a film structure having a buffer film formed on a substrate, the orientation direction of a metal film or a piezoelectric film formed on the buffer film can be aligned in a fixed direction. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 2 is a cross-sectional view of a membrane structure according to an embodiment. [Figure 2] FIG. 1 is a diagram illustrating a 42° rotated Y-cut Si substrate. [Figure 3]FIG. 2 is a cross-sectional view of a membrane structure according to an embodiment. [Figure 4] FIG. 2 is a cross-sectional view of a membrane structure according to an embodiment. [Figure 5] FIG. 10 is a cross-sectional view of a membrane structure according to a first modified example of the embodiment. [Figure 6] FIG. 10 is a cross-sectional view of a membrane structure according to a second modified example of the embodiment. [Figure 7] 1 is a plan view schematically showing a film forming apparatus according to an embodiment; [Figure 8] 1 is a cross-sectional view schematically showing an electron beam evaporation device provided in a film forming apparatus according to an embodiment. [Figure 9] FIG. 2 is a cross-sectional view schematically showing a DC sputtering device provided in the film forming apparatus of the embodiment. [Figure 10] 1 is a cross-sectional view schematically showing an RF sputtering device provided in a film forming apparatus according to an embodiment. [Figure 11] FIG. 2 is a flow chart showing some steps of a method for manufacturing a membrane structure according to an embodiment. [Figure 12] 10A and 10B are cross-sectional views of the membrane structure according to the embodiment during the manufacturing process. [Figure 13] 10A and 10B are cross-sectional views of the membrane structure according to the embodiment during the manufacturing process. [Figure 14] 1 is a graph showing an example of an ω-2θ spectrum of a film structure of an example by an XRD method. [Figure 15] 1 is a graph showing an example of a φ scan spectrum of a film structure of an example by an XRD method. [Figure 16] 1 is a graph showing an example of an ω-2θ spectrum of a film structure of an example by an XRD method. [Figure 17] 1 is a graph showing an example of a φ scan spectrum of a film structure of an example by an XRD method. [Figure 18] 1 is a graph showing the results of X-ray reciprocal space mapping of a film structure of an example. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0027] The disclosure is merely an example, and any appropriate modifications that a person skilled in the art can easily make while maintaining the gist of the invention are naturally included within the scope of the present invention. In addition, the drawings may be diagrammatic in width, thickness, shape, etc. of each part compared to the embodiment to make the explanation clearer, but these are merely examples and do not limit the interpretation of the present invention.

[0028] In addition, in this specification and each drawing, elements similar to those previously described with respect to the previous drawings are given the same reference numerals, and detailed descriptions thereof may be omitted as appropriate.

[0029] Furthermore, in the drawings used in the embodiments, hatching (shading) used to distinguish structures may be omitted depending on the drawing.

[0030] In the following embodiments, when a range is indicated as A to B, it means A or more and B or less unless otherwise specified.

[0031] (Embodiment) <Membrane structure> First, a film structure according to an embodiment of the present invention will be described. Fig. 1 is a cross-sectional view of the film structure according to the embodiment. Fig. 2 is a diagram illustrating a 42° rotated Y-cut Si substrate. Figs. 3 and 4 are cross-sectional views of the film structure according to the embodiment.

[0032] 1, a film structure 10 of this embodiment includes a substrate 11 which is a Si substrate, a buffer film 12 containing ZrO2 epitaxially grown on the substrate, and a metal film 13 epitaxially grown on the buffer film 12. Si represents silicon, and ZrO2 represents zirconium oxide.

[0033] In the techniques described in Patent Documents 1 and 2, the film structure includes a buffer film containing ZrO formed on a silicon layer or a silicon substrate, and a metal film containing Pt formed on the buffer film. However, depending on the type of silicon layer or silicon substrate, or the type of buffer film, it can be difficult to align the orientation of the metal film formed on the buffer film in a uniform direction. In such cases, when a piezoelectric film is further formed on the metal film, it can also be difficult to align the orientation of the piezoelectric film formed on the metal film in a uniform direction.

[0034] On the other hand, the substrate 11 of the film structure 10 of this embodiment is a rotated Y-cut Si substrate with an angle of 36° to 48°.

[0035] As shown in Figure 2, Si <110> The axis along the direction is the X axis, and the Si <100> When the axis along the direction is the Y-axis, for example, a 42° rotated Y-cut Si substrate is a substrate in which the Y-axis is aligned with the Si <110> The Si substrate 11f has an upper surface 11e perpendicular to a Y' axis, which is an axis rotated 42° around an X axis along the direction.

[0036] 14 to 18, which will be described later, buffer film 12 includes ZrO2 epitaxially grown on substrate 11, and metal film 13 includes a Pt film epitaxially grown on buffer film 12. This makes it easier to align the orientation direction of metal film 13 formed on buffer film 12 in a fixed direction, and easier to align the orientation direction of piezoelectric film 15 formed on metal film 13 in a fixed direction, thereby realizing a film structure in which the polarization direction of piezoelectric film 15 is aligned in a fixed direction.

[0037] Furthermore, when the rotation angle of the rotated Y-cut Si substrate, which is substrate 11, is 36° or more, the rotation angle is not too far from 42° compared to when the rotation angle is less than 36°. Therefore, similar to when substrate 11 is a rotated Y-cut Si substrate with a rotation angle of 42°, buffer film 12 contains ZrO2 epitaxially grown on substrate 11, and metal film 13 contains a Pt film epitaxially grown on buffer film 12.

[0038] Furthermore, when the rotation angle of the rotated Y-cut Si substrate, which is substrate 11, is 48° or less, the rotation angle is not too far from 42° compared to when the rotation angle exceeds 48°. Therefore, similar to when substrate 11 is a rotated Y-cut Si substrate with a rotation angle of 42°, buffer film 12 contains ZrO2 epitaxially grown on substrate 11, and metal film 13 contains a Pt film epitaxially grown on buffer film 12.

[0039] Here, the fact that a film is epitaxially grown means that the film is oriented in all three directions that are perpendicular to each other, that is, that the film is three-dimensionally oriented.

[0040] 3, a silicon-on-insulator (SOI) substrate, which is a semiconductor substrate, can be used instead of a Si substrate as the substrate 11 of the film structure 10 of this embodiment. That is, the substrate 11 of the film structure 10 of this embodiment is a Si substrate or an SOI substrate.

[0041] When an SOI substrate is used as the substrate 11, the substrate 11 includes a base body 11a made of Si, a BOX (Buried Oxide) layer 11b serving as an insulating layer that is a buried oxide film formed on the base body 11a, and a Si layer 11c serving as an SOI (Silicon On Insulator) layer formed on the BOX layer 11b. This makes it possible to easily form an electronic device made of a Micro Electro Mechanical System (MEMS) having a plurality of piezoelectric elements formed with high shape accuracy on the SOI substrate.

[0042] Furthermore, when an SOI substrate is used as the substrate 11, the substrate 11 includes a base 11a made of a 36° to 48° rotated Y-cut Si substrate, a BOX layer 11b which is an insulating layer formed on the base 11a, and a Si layer 11c which is an SOI layer formed on the BOX layer 11b. The Miller indices (orientation direction) of the crystal plane of the upper surface of the Si layer 11c, i.e., the main surface of the substrate 11, are the same as the Miller indices (orientation direction) of the crystal plane of the upper surface of the base 11a, i.e., the main surface of the base 11a.

[0043] When the base 11a is a 42° rotated Y-cut Si substrate and the Miller indices (orientation direction) of the crystal plane of the upper surface of the Si layer 11c, i.e., the main surface of the substrate 11, are the same as the Miller indices (orientation direction) of the crystal plane of the upper surface of the base 11a, i.e., the main surface of the base 11a, the buffer film 12 contains ZrO2 epitaxially grown on the Si layer 11c, and the metal film 13 contains a Pt film epitaxially grown on the buffer film 12, just as when the substrate 11 is a 42° rotated Y-cut Si substrate. This makes it easier to align the orientation of the metal film 13 formed on the buffer film 12 in a fixed direction, and easier to align the orientation of the piezoelectric film 15 formed on the metal film 13 in a fixed direction, thereby realizing a film structure in which the polarization direction of the piezoelectric film 15 is aligned in a fixed direction.

[0044] Furthermore, when the rotation angle of the rotated Y-cut Si substrate, which is the base 11a, is 36° or more, the rotation angle is not too far from 42° compared to when the rotation angle is less than 36°. Therefore, similar to when the base 11a is a rotated Y-cut Si substrate with a rotation angle of 42°, the buffer film 12 contains ZrO2 epitaxially grown on the Si layer 11c, and the metal film 13 contains a Pt film epitaxially grown on the buffer film 12.

[0045] Furthermore, when the rotation angle of the rotated Y-cut Si substrate, which is the base 11a, is 48° or less, the rotation angle is not too far from 42° compared to when the rotation angle exceeds 48°. Therefore, similar to when the base 11a is a rotated Y-cut Si substrate with a rotation angle of 42°, the buffer film 12 contains ZrO2 epitaxially grown on the Si layer 11c, and the metal film 13 contains a Pt film epitaxially grown on the buffer film 12.

[0046] Preferably, the metal film 13 includes a Pt film, where Pt stands for platinum.

[0047] By including ZrO2 epitaxially grown on the substrate 11 in the buffer film 12, the Pt film included in the metal film 13 can be oriented in a certain direction.

[0048] When the metal film 13 contains a Pt film, the Pt film is oriented in a certain direction, which makes it easier to align the orientation direction of the piezoelectric film 15 formed on the metal film 13 in a certain direction.

[0049] Preferably, the piezoelectric film 15 includes PZT, AlN, LiTaO3, or LiNbO3. PZT includes Pb(Zr 1-x Ti x )O3, which stands for lead zirconate titanate. AlN stands for aluminum nitride, LiTaO3 stands for lithium tantalate, and LiNbO3 stands for lithium niobate.

[0050] By including PZT, AlN, LiTaO3, or LiNbO3 in the piezoelectric film 15, the piezoelectric properties of the piezoelectric film 15 can be improved since the piezoelectric constant of PZT, AlN, LiTaO3, or LiNbO3 is larger than that of other materials.

[0051] When the metal film 13 includes an epitaxially grown Pt film, the film structure 10 preferably has an SrRuO3 (SRO) film, i.e., an SRO film 14, epitaxially grown on the metal film 13, as shown in Figure 4. SrRuO3 (SRO) stands for strontium ruthenate.

[0052] SRO has a perovskite structure. Therefore, when the film structure 10 has the SRO film 14 epitaxially grown on the metal film 13, the piezoelectric film 15 containing a complex oxide having a perovskite structure can be epitaxially grown on the substrate 11 more easily than when the film structure 10 does not have an SRO film epitaxially grown on the metal film 13. In this case, the film structure 10 has the piezoelectric film 15 epitaxially grown on the SRO film 14.

[0053] When the film structure 10 has an SRO film 14 epitaxially grown on the metal film 13, two diffraction peaks, each representing the SRO(110) plane of the SRO film 14, are observed in the in-plane X-ray diffraction pattern of the film structure, as will be described later with reference to FIG. 15 .

[0054] As a result, it is clear that the SRO film 14 is epitaxially grown, and it can be easily confirmed that the SRO film 14 is epitaxially grown on the 36° to 48° rotated Y-cut Si substrate. Furthermore, it is presumed that the SRO film 14 has 2-fold symmetry.

[0055] In addition, when the film structure 10 has the SRO film 14 epitaxially grown on the metal film 13, as shown in FIG. 4, the film structure 10 preferably has a piezoelectric film 15 epitaxially grown on the SRO film 14, such as Pb(Zr 1-x Ti x )O3(PZT) film, that is, a PZT film 15a containing PZT. PZT stands for lead zirconate titanate. This can improve the piezoelectric properties of the piezoelectric film 15.

[0056] In such a case, as will be described later with reference to FIG. 17, two diffraction peaks each representing the PZT (213) plane of the PZT film 15a are observed in the in-plane X-ray diffraction pattern of the film structure.

[0057] As a result, it is clear that the PZT film 15a is epitaxially grown, and it can be easily confirmed that the PZT film 15a is epitaxially grown on the 36° to 48° rotated Y-cut Si substrate. Furthermore, it is inferred that the PZT film 15a has two-fold symmetry.

[0058] Preferably, as will be described later with reference to FIG. 18, in X-ray reciprocal lattice space mapping of the film structure, three reciprocal lattice points respectively representing the PZT(110) plane of the PZT film 15a, the Si(220) plane of the substrate 11, and the PZT(112) plane of the PZT film 15a are arranged in the Qz direction.

[0059] In this case, it can be confirmed that the PZT film 15a is epitaxially grown, and it can be easily confirmed that the PZT film 15a is epitaxially grown on the 36° to 48° rotated Y-cut Si substrate. Furthermore, it is inferred that the PZT(110) plane of the PZT film 15a, which is perpendicular to the Si(100) plane (referred to as the Si(001) plane) that forms an angle of 42° with the surface of the rotated Y-cut Si substrate, and the Si(110) plane that is perpendicular to the Si(001) plane, are parallel to each other.

[0060] When the buffer film 12 contains ZrO epitaxially grown on the substrate 11, the SRO film 14 can be directly epitaxially grown on the buffer film 12 without the metal film 13 being formed on the buffer film 12, and the piezoelectric film 15 can be further epitaxially grown on the SRO film 14. In this case, the film structure 10 has the SRO film 14 epitaxially grown directly on the buffer film 12, and the piezoelectric film 15 epitaxially grown on the SRO film 14.

[0061] <First Modified Example of Membrane Structure> Next, a first modified example of the film structure of the present embodiment will be described. The film structure 10a of this first modified example differs from the film structure 10 of the embodiment in that a PZT film 15a is formed as the piezoelectric film 15 on the buffer film 12 without a metal film 13 therebetween. Figure 5 is a cross-sectional view of the film structure of the first modified example of the embodiment.

[0062] 5, the film structure 10a of the first modified example includes a substrate 11 that is a Si substrate, a buffer film 12 containing ZrO2 epitaxially grown on the substrate, and a PZT film 15a as a piezoelectric film 15 epitaxially grown on the buffer film 12. The substrate 11 is a 36° to 48° rotated Y-cut Si substrate or an SOI substrate including a base 11a (see FIG. 3) made of a 36° to 48° rotated Y-cut Si substrate, a BOX layer 11b (see FIG. 3) on the base 11a, and a Si layer 11c (see FIG. 3) that is an SOI layer made of a Si film on the BOX layer 11b, and the Miller indices of the crystal plane of the upper surface of the Si layer 11c are the same as the Miller indices of the crystal plane of the upper surface of the base 11a.

[0063] In this first modification, as in the embodiment, the substrate 11 is a 36° to 48° rotated Y-cut Si substrate, or the Miller indices (orientation) of the crystal plane of the upper surface of the Si layer 11c (see FIG. 3), i.e., the main surface of the substrate 11, are the same as the Miller indices (orientation) of the crystal plane of the upper surface of the base 11a (see FIG. 3), i.e., the main surface of the base 11a, which is a 36° to 48° rotated Y-cut Si substrate. This facilitates aligning the orientation of the piezoelectric film 15 formed on the buffer film 12 in a uniform direction, thereby achieving a film structure in which the polarization direction of the piezoelectric film 15 is aligned in a uniform direction. Furthermore, by forming a pair of comb-shaped electrodes on the upper surface of the piezoelectric film 15, it is possible to realize, for example, a surface acoustic wave (SAW) device with excellent piezoelectric properties. Although the metal film 13 is formed on the buffer film 12, the piezoelectric film 15 can also be formed on the metal film 13 without an SRO film interposed therebetween.

[0064] <Second Modified Example of Membrane Structure> Next, a second modified example of the membrane structure of this embodiment will be described below. Fig. 6 is a cross-sectional view of the membrane structure of the second modified example of this embodiment.

[0065] As shown in Fig. 6, the film structure 10b of the second modified example includes a substrate 11, which is a Si substrate, and a buffer film 12 containing ZrO2 epitaxially grown on the substrate. The substrate 11 is a 36° to 48° rotated Y-cut Si substrate. The substrate 11 is a 36° to 48° rotated Y-cut Si substrate or an SOI substrate including a base 11a (see Fig. 3) made of the 36° to 48° rotated Y-cut Si substrate, a BOX layer 11b (see Fig. 3) on the base 11a, and a Si layer 11c (see Fig. 3) that is an SOI layer made of a Si film on the BOX layer 11b. The Miller indices of the crystal plane of the upper surface of the Si layer 11c are the same as those of the crystal plane of the upper surface of the base 11a.

[0066] In the second modified example, as in the embodiment, the substrate 11 is a rotated Y-cut Si substrate with an angle of 36° to 48°, or the Miller indices (orientation direction) of the crystal plane of the upper surface of the Si layer 11c, i.e., the main surface of the substrate 11, are the same as the Miller indices (orientation direction) of the crystal plane of the upper surface of the base 11a, i.e., the main surface of the base 11a, which is a rotated Y-cut Si substrate with an angle of 36° to 48°. This makes it easier to align the orientation of the metal film 13 (see FIG. 1) formed on the buffer film 12 in a fixed direction, and easier to align the orientation of the piezoelectric film 15 (see FIG. 4) formed on the metal film 13 in a fixed direction, thereby realizing a film structure in which the polarization direction of the piezoelectric film 15 is aligned in a fixed direction.

[0067] <Film forming equipment> Next, a film forming apparatus as a manufacturing apparatus for a film structure according to an embodiment will be described. The film forming apparatus is a film forming apparatus for carrying out a manufacturing method for a film structure according to an embodiment, which will be described later with reference to FIGS. 1, 4, 6, and 11 to 13.

[0068] Fig. 7 is a plan view schematically showing a film forming apparatus according to an embodiment. Fig. 8 is a cross-sectional view schematically showing an electron beam evaporation apparatus provided in the film forming apparatus according to an embodiment. Fig. 9 is a cross-sectional view schematically showing a DC sputtering apparatus provided in the film forming apparatus according to an embodiment. Fig. 10 is a cross-sectional view schematically showing an RF sputtering apparatus provided in the film forming apparatus according to an embodiment.

[0069] 7, film formation apparatus 20 of this embodiment includes load lock chamber 21, transfer chamber 22, transfer robot 23, deposition chamber 24 which is an electron beam deposition apparatus, sputtering chamber 25 which is a DC sputtering apparatus, sputtering chamber 26 which is an RF sputtering apparatus, sputtering chamber 27 which is also an RF sputtering apparatus, and control unit 28. Note that while Fig. 7 shows the film formation apparatus as a multi-chamber apparatus in which deposition chamber 24 and each sputtering chamber are connected to each other via transfer chamber 22, deposition chamber 24 and each sputtering chamber may be installed separately.

[0070] The deposition chamber 24, which is an electron beam deposition apparatus, is a buffer film forming section that forms a buffer film 12 (see FIG. 1) on the substrate 11. The sputtering chamber 25, which is a DC sputtering apparatus, is a metal film forming section that forms a metal film 13 (see FIG. 1) on the buffer film 12. The sputtering chamber 26, which is an RF sputtering apparatus, is an SRO film forming section that forms an SRO film 14 (see FIG. 4) on the metal film 13. The sputtering chamber 27, which is an RF sputtering apparatus, is a piezoelectric film forming section that forms a PZT film 15a (see FIG. 4), which is a piezoelectric film 15, on the SRO film 14. The control section 28 controls the operations of the load lock chamber 21, the transfer chamber 22, the transfer robot 23, the deposition chamber 24, the sputtering chamber 25, the sputtering chamber 26, and the sputtering chamber 27. The control unit 28 includes a process controller (computer) 31 that has a central processing unit (CPU) and controls each part of the film forming apparatus 20 , a user interface unit 32 , and a storage unit 33 .

[0071] A vacuum pump (not shown) is connected to the load lock chamber 21, a substrate (for example, a Si wafer) to be subjected to film formation processing is introduced into the load lock chamber 21, and the inside of the load lock chamber 21 is evacuated by the vacuum pump.

[0072] The transfer chamber 22 is connected to the load lock chamber 21 via a gate valve 34. A transfer robot 23 is disposed in the transfer chamber 22. A vacuum pump (not shown) is connected to the transfer chamber 22, and the inside of the transfer chamber 22 is evacuated by the vacuum pump.

[0073] As shown in FIG. 8, the deposition chamber 24, which is an electron beam deposition apparatus, has a film formation chamber 41, and a deposition source 42 is arranged at the bottom of the film formation chamber 41. A substrate holder 43 that holds a substrate 11 is arranged at the top of the film formation chamber 41. The substrate holder 43 is arranged opposite the deposition source 42. The deposition source 42 has a crucible that contains a deposition material containing zirconium (Zr) and an electron gun (EB gun) 44. A cooling mechanism (not shown) is attached to the crucible. The deposition source 42 irradiates the deposition material with an electron beam from the electron gun 44 to heat it and evaporate the deposition material.

[0074] The substrate holder 43 holds the substrate 11. The substrate holder 43 is attached to a rotation mechanism 45, which can rotate the substrate holder 43. A heater (infrared lamp) 46 serving as a substrate heating mechanism is disposed on the upper part of the substrate holder 43 (the part opposite the lower part where the substrate 11 is held). A reflector (not shown) is disposed on the lower surface of the substrate holder 43 (the surface on which the substrate is placed). The substrate holder 43 also includes a substrate cooling mechanism (not shown) for lowering the substrate temperature.

[0075] A reactive gas supply mechanism (not shown) that supplies a reactive gas is connected to the film formation chamber 41. The reactive gas is, for example, oxygen gas (O2). In addition, an exhaust pump system (not shown) that reduces the internal pressure of the film formation chamber 41 to a predetermined pressure is connected to the film formation chamber 41.

[0076] The film forming apparatus 20 of this embodiment may have a boat-type evaporation apparatus, a reactive sputtering apparatus, or an RF ion plating apparatus as the buffer film forming section instead of the electron beam evaporation apparatus.

[0077] 9, sputtering chamber 25, which is a DC sputtering apparatus, includes chamber 51 and substrate holder 52 that is provided in chamber 51 and holds substrate 11. Chamber 51, substrate 11, and substrate holder 52 are grounded. Substrate holder 52 preferably has a heater (not shown) as a substrate heating mechanism that heats substrate 11.

[0078] The sputtering chamber 25 is provided in the chamber 51 and includes a target holder 54 that holds a target 53 serving as a sputtering target. The target holder 54 is arranged so that the target 53 held by the target holder 54 faces the substrate 11 held by the substrate holder 52. The sputtering chamber 25 also includes a vacuum pump or other evacuation mechanism 55 that evacuates the chamber 51, and a power supply mechanism 56 that is electrically connected to the target holder 54 and that supplies DC power to the target 53.

[0079] 10, sputtering chamber 26, which is an RF sputtering apparatus, includes a chamber 61 and a substrate holder 62 that is provided in chamber 61 and holds substrate 11. Chamber 61, substrate 11, and substrate holder 62 are grounded. Substrate holder 62 preferably has a heater (not shown) that heats substrate 11.

[0080] The sputtering chamber 26 is provided in a chamber 61 and includes a target holder 64 that holds a target 63 as a sputtering target. The target holder 64 is disposed so that the target 63 held by the target holder 64 faces the substrate 11 held by the substrate holder 62. The target 63 may be, for example, a silicon dioxide film having a resistivity of 1×10 7 It is also possible to use a target containing an insulator with a resistance of Ω·cm or more.

[0081] The sputtering chamber 26 is equipped with a power supply mechanism 65. For example, a high-frequency power supply can be used as the power supply mechanism 65. The power supply mechanism 65 is electrically connected to a matching box 66, which is electrically connected to the target holder 64. The power supply mechanism 65 may supply high-frequency power to the target 63 via the target holder 64, or the power supply mechanism 65 may supply high-frequency power directly to the target 63.

[0082] The sputtering chamber 26 is equipped with a first gas introduction source 67 that introduces a rare gas into the chamber 61, and a second gas introduction source 68 that introduces oxygen (O2) gas into the chamber 61. The film forming apparatus 20 also has a vacuum exhaust mechanism 69 such as a vacuum pump that evacuates the chamber 61. Preferably, the rare gas introduced into the chamber 61 by the first gas introduction source 67 is argon (Ar) gas.

[0083] Furthermore, sputtering chamber 26 preferably includes a flow rate control unit (not shown) that controls the ratio between the flow rate of Ar gas introduced by first gas introduction source 67 and the flow rate of O gas introduced by second gas introduction source 68 during film formation. Furthermore, sputtering chamber 26 preferably includes a pressure control unit (not shown) that controls the pressure inside chamber 61 during film formation.

[0084] The sputtering chamber 26 also includes a magnet 71 that applies a magnetic field to the target 63 and a rotation mechanism 72 that rotates the magnet 71.

[0085] Although not shown, the sputtering chamber 27 can be configured in the same manner as the sputtering chamber 26.

[0086] As described above, the control unit 28 includes a process controller (computer) 31 that has a CPU and controls each part of the film forming apparatus 20, a user interface unit 32, and a storage unit 33.

[0087] The user interface unit 32 is composed of a keyboard through which an operator inputs commands to manage the film forming apparatus 20, a display that visualizes and displays the operating status of the film forming apparatus 20, and the like.

[0088] The storage unit 33 stores recipes that store control programs (software) or process condition data for realizing various processes executed in the film forming apparatus 20 under the control of the process controller 31. Then, as needed, an arbitrary recipe is called from the storage unit 33 and executed by the process controller 31 in response to an instruction from the user interface unit 32, whereby the desired process is performed in the film forming apparatus 20 under the control of the process controller 31.

[0089] Furthermore, recipes such as control programs or processing condition data may be recorded on a computer-readable recording medium, such as a hard disk, a compact disc (CD), a flexible disk, or a semiconductor memory. In such a case, the recording medium on which the recipe is recorded is set in the storage unit 33, and the recipe can be called up from the recording medium set in the storage unit 33 and executed by the process controller 31. Alternatively, the recipe can be called up online by transmitting it as needed from another device, for example, via a dedicated line, and executed by the process controller 31.

[0090] <Membrane structure manufacturing method> Next, a method for manufacturing a membrane structure according to an embodiment will be described with reference to Figures 1, 4, 6, and 11 to 13. Figure 11 is a flow chart showing some steps of the method for manufacturing a membrane structure according to an embodiment. Figures 12 and 13 are cross-sectional views of the membrane structure according to an embodiment during the manufacturing process.

[0091] First, a substrate 11, which is a 36° to 48° rotated Y-cut Si substrate, is prepared as shown in Fig. 6. At this time, an oxide film such as an SiO2 film may be formed on the upper surface of the substrate 11.

[0092] 14 to 18, which will be described later, buffer film 12 includes ZrO2 epitaxially grown on substrate 11, and metal film 13 includes a Pt film epitaxially grown on buffer film 12. This makes it easier to align the orientation direction of metal film 13 formed on buffer film 12 in a fixed direction, and also makes it easier to align the orientation direction of piezoelectric film 15 (see FIG. 4) formed on metal film 13 in a fixed direction, thereby realizing a film structure in which the polarization direction of piezoelectric film 15 is aligned in a fixed direction.

[0093] Furthermore, when the rotation angle of the rotated Y-cut Si substrate is 36° or more, the rotation angle is not too far from 42° compared to when the rotation angle is less than 36°. Therefore, similar to the case of a 42° rotated Y-cut Si substrate, the buffer film 12 contains ZrO2 epitaxially grown on the substrate 11, and the metal film 13 contains a Pt film epitaxially grown on the buffer film 12.

[0094] Furthermore, when the rotation angle of the rotated Y-cut Si substrate is 48° or less, the rotation angle is not too far from 42° compared to when the rotation angle exceeds 48°. Therefore, similar to the case of a 42° rotated Y-cut Si substrate, the buffer film 12 contains ZrO2 epitaxially grown on the substrate 11, and the metal film 13 contains a Pt film epitaxially grown on the buffer film 12.

[0095] 12, instead of the substrate 11 which is a Si substrate, an SOI substrate may be prepared. When an SOI substrate is used as the substrate 11, the substrate 11 includes a base 11a made of a 36° to 48° rotated Y-cut Si substrate, a BOX layer 11b formed on the base 11a, and a Si layer 11c which is an SOI layer formed on the BOX layer. The Miller indices (orientation direction) of the crystal plane of the upper surface of the Si layer 11c, i.e., the main surface of the substrate 11, are the same as the Miller indices (orientation direction) of the crystal plane of the upper surface of the base 11a, i.e., the main surface of the base 11a.

[0096] When the base 11a is a 42° rotated Y-cut Si substrate and the Miller indices (orientation) of the crystal plane of the upper surface of the Si layer 11c, i.e., the main surface of the substrate 11, are the same as the Miller indices (orientation) of the crystal plane of the upper surface of the base 11a, i.e., the main surface of the base 11a, the buffer film 12 contains ZrO2 epitaxially grown on the Si layer 11c, and the metal film 13 contains a Pt film epitaxially grown on the buffer film 12, just as in the case where the substrate 11 is a 42° rotated Y-cut Si substrate. This makes it easier to align the orientation of the metal film 13 formed on the buffer film 12 in a fixed direction, and also makes it easier to align the orientation of the piezoelectric film 15 (see FIG. 4) formed on the metal film 13 in a fixed direction, thereby realizing a film structure in which the polarization direction of the piezoelectric film 15 is aligned in a fixed direction.

[0097] Furthermore, when the rotation angle of the rotated Y-cut Si substrate, which is the base 11a, is 36° or more, the rotation angle is not too far from 42° compared to when the rotation angle is less than 36°. Therefore, similar to when the base 11a is a rotated Y-cut Si substrate with a rotation angle of 42°, the buffer film 12 contains ZrO2 epitaxially grown on the Si layer 11c, and the metal film 13 contains a metal film epitaxially grown on the buffer film 12.

[0098] Furthermore, when the rotation angle of the rotated Y-cut Si substrate, which is the base 11a, is 48° or less, the rotation angle is not too far from 42° compared to when the rotation angle exceeds 48°. Therefore, similar to when the base 11a is a rotated Y-cut Si substrate with a rotation angle of 42°, the buffer film 12 contains ZrO2 epitaxially grown on the Si layer 11c, and the metal film 13 contains a metal film epitaxially grown on the buffer film 12.

[0099] Next, as shown in FIG. 6, a buffer film 12 is formed on the substrate 11 (Step S1 in FIG. 11).

[0100] In step S1, first, the substrate 11 is carried into the deposition chamber 24 (see FIG. 7) by the transfer robot 23 (see FIG. 7), and the carried-in substrate 11 is held by the substrate holder 43 (see FIG. 8). In addition, with the substrate 11 held by the substrate holder 43 (see FIG. 8) placed in a certain vacuum atmosphere, the substrate 11 is heated to, for example, 700° C. by a heater 46 (see FIG. 8) serving as a substrate heating mechanism.

[0101] In step S1, an electron beam from the electron gun 44 (see FIG. 8) is then irradiated onto the zirconium (Zr) single crystal deposition material to heat and evaporate the deposition material. At this time, the evaporated Zr reacts with oxygen on the substrate 11 heated to, for example, 700°C, to form a zirconium oxide (ZrO2) film. In this way, a buffer film 12 containing epitaxially grown ZrO2 is formed on the substrate 11.

[0102] Next, an epitaxially grown metal film 13 is formed on the buffer film 12 (Step S2 in FIG. 11).

[0103] In step S2, first, the substrate 11 having the buffer film 12 formed thereon is carried into the sputtering chamber 25 (see FIG. 7) by the transfer robot 23 (see FIG. 7), and the carried-in substrate 11 is held by the substrate holder 52 (see FIG. 9). Further, with the substrate 11 placed in a constant vacuum atmosphere, the substrate 11 is heated to, for example, 450 to 600°C by the substrate heating mechanism.

[0104] In step S2, a target made of, for example, Pt is then DC sputtered to form a metal film 13 containing, for example, a Pt film on the buffer film 12 as shown in FIG.

[0105] Preferably, in step S2, an epitaxially grown metal film 13 including a Pt film is formed on the buffer film 12.

[0106] The buffer film 12 contains ZrO2 epitaxially grown on the substrate 11, so that the Pt film contained in the metal film 13 can be oriented in a fixed direction. Furthermore, since the metal film 13 contains a Pt film, the Pt film is oriented in a fixed direction, which makes it easier to align the orientation direction of the piezoelectric film 15 (see FIG. 4) formed on the metal film 13 in a fixed direction.

[0107] After forming metal film 13 including an epitaxially grown Pt film in step S2, as shown in Fig. 13, preferably, an SRO film 14 is formed epitaxially on metal film 13 (step S3 in Fig. 11). This makes it easier to epitaxially grow a piezoelectric film including a complex oxide having a perovskite structure on substrate 11.

[0108] Preferably, the piezoelectric film 15 contains PZT, AlN, LiTaO3, or LiNbO3. When the piezoelectric film 15 contains PZT, AlN, LiTaO3, or LiNbO3, the piezoelectric constant of PZT, AlN, LiTaO3, or LiNbO3 is larger than that of other materials, and therefore the piezoelectric characteristics can be improved.

[0109] Furthermore, in step S3, after forming the SRO film 14 epitaxially on the metal film 13, as shown in Fig. 4, preferably, a PZT film 15a serving as the piezoelectric film 15 is formed epitaxially on the SRO film 14. This improves the piezoelectric characteristics of the piezoelectric film 15. Note that, as described in the first modified example of the embodiment with reference to Fig. 5, the PZT film 15a serving as the piezoelectric film 15 can also be formed on the buffer film 12 without the metal film 13 therebetween.

[0110] When the SRO film 14 is formed epitaxially on the metal film 13 in step S3, two diffraction peaks each representing the SRO (110) plane are observed in the in-plane X-ray diffraction pattern of the film structure, as will be described later with reference to FIG. 15 , and it can be easily confirmed that the SRO film 14 is epitaxially grown.

[0111] Furthermore, when the SRO film 14 is formed epitaxially on the metal film 13 in step S3, a PZT film 15a, which is the piezoelectric film 15, is preferably formed epitaxially on the SRO film 14. In such a case, as will be described later with reference to FIG. 17, two diffraction peaks, each representing the PZT (213) plane of the PZT film 15a, are observed in the in-plane X-ray diffraction pattern of the film structure, and it can be easily confirmed that the PZT film 15a is epitaxially grown.

[0112] Preferably, as will be described later with reference to FIG. 18, in X-ray reciprocal lattice space mapping of the film structure, three reciprocal lattice points respectively representing the PZT(110) plane of the PZT film 15a, the Si(220) plane of the substrate 11, and the PZT(112) plane of the PZT film 15a are arranged in the Qz direction.

[0113] In this case, it can be confirmed that the PZT film 15a is epitaxially grown, and it can be easily confirmed that the PZT film 15a is epitaxially grown on the 36° to 48° rotated Y-cut Si substrate. Furthermore, it is inferred that the PZT(110) plane of the PZT film 15a, which is perpendicular to the Si(100) plane (referred to as the Si(001) plane) that forms an angle of 42° with the surface of the rotated Y-cut Si substrate, and the Si(110) plane that is perpendicular to the Si(001) plane, are parallel to each other.

[0114] The film formation apparatus 20 can also be used to carry out the manufacturing process of the film structure of this embodiment. In this case, a recipe such as a control program or processing condition data for the manufacturing process of the film structure of this embodiment is a program for causing the control unit 28 provided in the film formation apparatus 20 to execute the manufacturing process of the film structure of this embodiment. Furthermore, a recording medium set in the storage unit 33 and recording the control program or the recipe such as processing condition data is a recording medium recording a program for causing the control unit 28 provided in the film formation apparatus 20 to execute the manufacturing process of the film structure of this embodiment. Furthermore, the control unit 28 controls the operations of the buffer film formation unit (evaporation chamber 24), the metal film formation unit (sputtering chamber 25), and the SRO film formation unit (sputtering chamber 26) so that the buffer film formation unit, the metal film formation unit, and the SRO film formation unit execute the manufacturing process of the film structure of this embodiment. [Example]

[0115] The present embodiment will be described in more detail below based on examples, but the present invention is not limited to the following examples.

[0116] (Example) The membrane structure 10 described in the embodiment with reference to FIG. 4 was formed as the membrane structure of the example.

[0117] [Membrane structure formation] A method for forming the film structure of the example will be described below: First, a 42° rotated Y-cut Si substrate was prepared as a substrate.

[0118] Next, a ZrO2 film was formed as a buffer film on the wafer as a substrate by electron beam evaporation.

[0119] Next, a Pt film was formed as a metal film on the ZrO2 film by sputtering.

[0120] Next, an SRO film was formed on the Pt film by sputtering.

[0121] Next, a PZT film was formed on the SRO film by sputtering.

[0122] [ω-2θ spectrum and φ scan spectrum of the membrane structure] For the film structure of the example, ω-2θ spectrum (out-of-plane X-ray diffraction pattern) and φ scan spectrum (in-plane X-ray diffraction pattern) were measured by XRD. That is, for the film structure of the example where the PZT film was formed, X-ray diffraction measurement by ω-2θ scan (out-of-plane measurement) and X-ray diffraction measurement by φ scan (in-plane measurement) were performed.

[0123] Fig. 14 is a graph showing an example of an ω-2θ spectrum measured by an XRD method for the film structure of the example. The horizontal axis of the graph in Fig. 14 represents the angle 2θ, and the vertical axis of the graph in Fig. 14 represents the X-ray intensity (this also applies to Fig. 16 described later). Fig. 14 also shows the range of 20°≦2θ≦110° (this also applies to Fig. 16 described later). In Fig. 14, M-ZrO2 refers to ZrO2 having a monoclinic crystal structure.

[0124] In Fig. 14, when the angle (e.g., ω-θ) between the plane (measurement plane) for which the lattice spacing (lattice constant) is found and the substrate surface is equal to 0°, it is represented as 0° (the same applies to Fig. 16 described later). In addition, when the angle between the measurement plane and the substrate surface is different from 0°, it is represented as 15°, 30°, 45°, 60°, or 75°, which are the angles between the measurement plane and the substrate surface (the same applies to Fig. 16 described later). Note that when the angle between the measurement plane and the substrate surface is less than 90°, it corresponds to out-of-plane measurement, and when the angle between the measurement plane and the substrate surface is equal to 90°, it corresponds to in-plane measurement.

[0125] In the example shown in Figure 14, the angle between the measurement surface and the substrate surface was around 30°, and the diffraction peak of the Si(220) plane of the Si substrate was used for alignment. Six ω-2θ spectra were then measured by changing the angle between the measurement surface and the substrate surface to 0°, 15°, 30°, 45°, 60°, and 75°.

[0126] In the six ω-2θ spectra shown in Figure 14, diffraction peaks from the ZrO2(111), SRO(110), Pt(111), and SRO(220) planes were observed in addition to the diffraction peaks from the Si(220) and Si(440) planes. Specifically, when the angle between the measurement plane and the substrate surface was 0°, diffraction peaks from the ZrO2(111) and Pt(111) planes were observed. When the angle between the measurement plane and the substrate surface was 30°, diffraction peaks from the SRO(110), Si(220), SRO(220), and Si(440) planes were observed. Thus, the diffraction peaks observed in the six ω-2θ spectra were completely different.

[0127] Therefore, it was confirmed that in the film structure of the example, a ZrO2 film, a Pt film, and an SRO film were formed on a Si substrate. Furthermore, it was confirmed that each of the ZrO2 film, the Pt film, and the SRO film of the film structure of the example was oriented in all three mutually orthogonal directions, i.e., three-dimensionally oriented, and epitaxially grown.

[0128] Fig. 15 is a graph showing an example of a φ scan spectrum of the film structure of the example by the XRD method. The horizontal axis of the graph in Fig. 15 represents the angle φ, and the vertical axis of the graph in Fig. 15 represents the X-ray intensity (this also applies to Fig. 17 described later). Fig. 15 also shows the range of 0°≦φ≦360° (this also applies to Fig. 17 described later).

[0129] In the example shown in Figure 15, a φ scan was performed with the angle between the measurement surface and the substrate surface at approximately 90° (in-plane measurement) and 2θ adjusted to be equal to the angle corresponding to the diffraction peak of the SRO(110) plane.

[0130] In the φ scan shown in Figure 15, one diffraction peak representing the Pt(220) plane was observed at an angle of φ=266°, and two diffraction peaks representing the SRO(110) plane were observed at two angle positions of φ=195° and φ=337° (angle difference Δφ=142°). This indicates that a Pt film grew epitaxially on the Si substrate, and an SRO film grew epitaxially on the Pt film. Furthermore, it is inferred that the SRO film has two-fold symmetry.

[0131] Fig. 16 is a graph showing an example of an ω-2θ spectrum measured by XRD for the film structure of the example. In the example shown in Fig. 16, the angle between the measurement surface and the substrate surface was set to about 45°, and the diffraction peak of the PZT (213) plane of the PZT film was used to align the axis. Then, the angle between the measurement surface and the substrate surface was changed to 0°, 15°, 30°, 45°, 60°, and 75°, and six ω-2θ spectra were measured.

[0132] In the six ω-2θ spectra shown in Figure 16, diffraction peaks from the PZT(110), Pt(111), PZT(112), PZT(213), and PZT(104) planes were observed. Specifically, when the angle between the measurement surface and the substrate surface was 0°, a diffraction peak from the Pt(111) plane was observed. When the angle between the measurement surface and the substrate surface was 15°, a diffraction peak from the PZT(112) plane was observed. When the angle between the measurement surface and the substrate surface was 30°, a diffraction peak from the PZT(110) plane was observed. When the angle between the measurement surface and the substrate surface was 45°, a diffraction peak from the PZT(213) plane was observed. When the angle between the measurement surface and the substrate surface was 75°, a diffraction peak from the PZT(104) plane was observed. Thus, the diffraction peaks observed in the six ω-2θ spectra were completely different.

[0133] Therefore, it was confirmed that a Pt film and a PZT film were formed in the film structure of the example. Furthermore, it was confirmed that the Pt film and the PZT film of the film structure of the example were oriented in all three mutually orthogonal directions, that is, three-dimensionally oriented, and epitaxially grown.

[0134] Fig. 17 is a graph showing an example of a φ-scan spectrum of the film structure of the example measured by XRD. In the example shown in Fig. 17, the φ-scan was performed with the angle between the measurement surface and the substrate surface at approximately 90° (in-plane measurement) and 2θ adjusted to be equal to the angle corresponding to the diffraction peak of the PZT (213) plane.

[0135] In the φ scan shown in Figure 17, two diffraction peaks representing the PZT (213) plane were observed. This confirmed that the PZT film was epitaxially grown. Furthermore, it is inferred that the PZT film has two-fold symmetry.

[0136] [X-ray reciprocal space mapping of membrane structures] Next, X-ray reciprocal lattice space mapping was performed on the film structure of the example. X-ray reciprocal lattice space mapping is a method of observing the film to be measured in three dimensions to confirm fluctuations in lattice constants and tilts of lattice planes.

[0137] Fig. 18 is a graph showing the results of X-ray reciprocal lattice space mapping of the film structure of the example. The horizontal axis of Fig. 18 represents the Qx direction, which is the direction in reciprocal lattice space corresponding to the lattice constant in the direction parallel to the Si(100) plane (referred to as the Si(001) plane) of the Si substrate, which forms an angle of 42° with the surface of the 42° rotated Y-cut Si substrate in real space, and the vertical axis of Fig. 18 represents the Qz direction, which is the direction in reciprocal lattice space corresponding to the direction perpendicular to the Si(001) plane in real space.

[0138] 18, in the X-ray reciprocal lattice space mapping of the film structure of the example, the reciprocal lattice points are not distributed in a ring shape around the origin, but are distributed as points. This confirms that each layer of the film structure of the example is oriented in all three mutually orthogonal directions, i.e., three-dimensionally oriented, and has grown epitaxially.

[0139] 18, in the X-ray reciprocal lattice space mapping of the film structure of the example, three reciprocal lattice points, each representing the PZT(110) plane of the PZT film, the Si(220) plane of the substrate, and the PZT(112) plane of the PZT film, are aligned in the Qz direction. This confirms that the PZT film of the film structure of the example is epitaxially grown. Furthermore, it is inferred that the PZT(110) plane of the PZT film, which is perpendicular to the Si(100) plane (referred to as the Si(001) plane) of the Si substrate, which forms an angle of 42° with the surface of the rotated Y-cut Si substrate, and the Si(110) plane, which is perpendicular to the Si(001) plane, are parallel to each other.

[0140] In the examples, a 42° rotated Y-cut Si substrate was used. However, although detailed description is omitted, when a 36° rotated Y-cut Si substrate and a 48° rotated Y-cut Si substrate were used instead of the 42° rotated Y-cut Si substrate, and when the SOI substrate described with reference to Fig. 3 was used as substrate 11, substantially the same results as when a 42° rotated Y-cut Si substrate was used were obtained. Therefore, it was confirmed that substantially the same results were obtained when a Si substrate with any cut angle of 36° to 48° rotated Y-cut Si substrate was used, and when the SOI substrate described with reference to Fig. 3 was used as substrate 11.

[0141] The invention made by the inventor has been specifically described above based on the embodiments thereof, but it goes without saying that the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit of the invention.

[0142] Within the scope of the concept of the present invention, a person skilled in the art may conceive of various modifications and alterations, and it is understood that these modifications and alterations also fall within the scope of the present invention.

[0143] For example, any embodiment in which a person skilled in the art has appropriately added or deleted components or modified the design, or added or omitted steps or modified conditions, is included within the scope of the present invention as long as it contains the essence of the present invention. [Explanation of symbols]

[0144] 10, 10a, 10b membrane structure 11 Circuit Board 11a Base 11b BOX layer 11c Si layer 11e Top side 11f Si substrate 12 Buffer film 13 Metal Film 14 SRO membrane 15 Piezoelectric film 15a PZT membrane 20 Film deposition equipment 21 Load Lock Chamber 22 Transport Room 23 Transport robot 24 evaporation chamber 25~27 Sputtering chamber 28 Control Unit 31 Process Controller 32 User Interface Section 33 Storage section 34 Gate valve 41 Deposition chamber 42 Vapor deposition source 43 PCB holder 44 Electron Gun 45 Rotation mechanism 46 Heater Chambers 51 and 61 52, 62 Board holding part 53, 63 targets 54, 64 Target holder 55, 69 Vacuum pumping mechanism 56 Power supply mechanism 65 Output supply mechanism 66 Matching box 67 First gas introduction source 68 Secondary Gas Source 71 Magnet 72 Rotation mechanism

Claims

1. A substrate; a buffer film formed on the substrate; and the substrate is a 36° to 48° rotated Y-cut Si substrate, or an SOI substrate including a base body made of a 36° to 48° rotated Y-cut Si substrate, an insulating layer on the base body, and an SOI layer made of a Si film on the insulating layer; The 36° to 48° rotated Y-cut Si substrate is a Si substrate having an upper surface perpendicular to a Y'-axis, which is an axis obtained by rotating the Y-axis by 36° to 48° around the X-axis, where the axis along the Si<110> direction is the X-axis and the axis along the Si<100> direction is the Y-axis; Miller indices of a crystal plane of the upper surface of the SOI layer are the same as Miller indices of a crystal plane of the upper surface of the substrate; The buffer film is a ZrO film epitaxially grown on the substrate. ２ A membrane structure comprising:

2. 2. The film structure according to claim 1, further comprising a metal film epitaxially grown on the buffer film.

3. The film structure according to claim 2 , wherein the metal film contains Pt.

4. 4. The film structure according to claim 2, further comprising an SRO film epitaxially grown on the metal film.

5. 4. The film structure according to claim 2, further comprising a piezoelectric film epitaxially grown on the metal film.

6. 5. The film structure according to claim 4, further comprising a piezoelectric film epitaxially grown on the SRO film.

7. 5. The film structure according to claim 4, wherein two diffraction peaks each representing an SRO (110) plane of the SRO film are observed in an in-plane X-ray diffraction pattern of the film structure.

8. The film structure according to claim 1 , further comprising a piezoelectric film epitaxially grown on the buffer film.

9. The piezoelectric film is made of PZT, AlN, LiTaO ３ or LiNbO ３ The membrane structure according to claim 5 or 6, comprising:

10. the piezoelectric film is a PZT film containing PZT, 7. The film structure according to claim 6, wherein two diffraction peaks each representing a PZT (213) plane of the PZT film are observed in an in-plane X-ray diffraction pattern of the film structure.

11. (a) providing a substrate; (b) forming a buffer film on the substrate; and In the step (a), a 36° to 48° rotated Y-cut Si substrate or an SOI substrate including a base body made of a 36° to 48° rotated Y-cut Si substrate, an insulating layer on the base body, and an SOI layer made of a Si film on the insulating layer is prepared; The 36° to 48° rotated Y-cut Si substrate is a Si substrate having an upper surface perpendicular to a Y'-axis, which is an axis obtained by rotating the Y-axis by 36° to 48° around the X-axis, where the axis along the Si<110> direction is the X-axis and the axis along the Si<100> direction is the Y-axis; Miller indices of a crystal plane of the upper surface of the SOI layer are the same as Miller indices of a crystal plane of the upper surface of the substrate; In the step (b), ZrO epitaxially grown on the substrate ２ The method for manufacturing a film structure includes forming the buffer film.

12. (c) forming an epitaxially grown metal film on the buffer film; and The method for manufacturing a film structure according to claim 11 , wherein the metal film contains Pt.

13. (d) forming an epitaxially grown SRO film on the metal film; and 13. The method for producing a film structure according to claim 12, wherein two diffraction peaks each representing an SRO (110) plane of the SRO film are observed in an in-plane X-ray diffraction pattern of the film structure.

14. (e) forming an epitaxially grown piezoelectric film on the metal film; and The piezoelectric film is made of PZT, AlN, LiTaO ３ or LiNbO ３ The method for producing the membrane structure according to claim 12, comprising:

Images