TW202223125A - Film-forming device - Google Patents

Abstract

The film-forming device according to one embodiment of the present invention has: a chamber 21 electrically connected to a grounding potential; a target TG disposed in the chamber; a power supply section 32 that supplies high-frequency power to the target; gas supply sections 23, 24 that supply a gas to the inside of the chamber; a substrate holding insulating section 25b, which is disposed in the chamber, and which holds a substrate SB by having the substrate face the target; a conductive supporting section 42 that supports the substrate holding insulating section; and a first insulating member 53 disposed between the conductive supporting section and the chamber. The conductive supporting section is electrically floating from the chamber due to the first insulating member, the substrate is held by the substrate holding insulating section when an outer peripheral section of the substrate comes into contact with the substrate holding insulating section, the substrate is electrically floating from the conductive supporting section, and the substrate holding insulating section does not overlap a center section of the substrate in plan view.

Description

Film forming device

The present invention relates to a film forming apparatus and a film forming method.

As a film structure including a substrate, a conductive film formed on the substrate, and a piezoelectric film formed on the conductive film, there are known a conductive film including a substrate, a platinum-containing film formed on the substrate, and a conductive film formed on the substrate. A film structure of a piezoelectric film containing lead zirconate titanate (PZT) on a conductive film.

In International Publication No. 2016/009698 (Patent Document 1), it is disclosed that a ferroelectric ceramic is provided with a Pb(Zr _1-A Ti _A )O ₃ film, which is formed on the Pb(Zr _1-A Ti _{A )} ) On the Pb(Zr _1-x Ti _x )O ₃ film on the O ₃ film, A and x satisfy the technology of 0≦A≦0.1 and 0.1<x<1.

In Japanese Patent Laid-Open No. 2014-84494 (Patent Document 2), it is disclosed that YSZ (8%Y ₂ O ₃ +92% ZrO ₂ ), CeO ₂ , and LaSrCoO ₃ are sequentially laminated on a silicon substrate (Si) in advance. The technology of forming a PZT (lead zirconate titanate) thin film on the buffer layer formed by the film. In particular, Patent Document 2 discloses a technique in which LaSrCoO ₃ (LSCO) rotates the lattice of other films by 45°.

In Non-Patent Document 1, it is disclosed that a buffer layer in which YSZ, CeO ₂ , La _0.5 Sr _0.5 CoO ₃ (LSCO), and SrRuO ₃ (SRO) are laminated in this order is formed on a resilicon substrate, and on the buffer layer, a buffer layer is formed. The technology of forming c-axis oriented 0.06Pb(Mn _1/3 , Nb _2/3 )O ₃ -0.94Pb(Zr _0.5 Ti _0.5 )O ₃ (PMnN-PZT) epitaxial thin films. In Non-Patent Document 1, a technique of rotating the crystal lattice of PMnN-PZT by 45° with respect to silicon in the in-plane direction is disclosed.

In Non-Patent Document ₂ , it is disclosed that the relative permittivity of PbTiO3 grown by a flux method using a magnesium oxide single crystal crucible is 150 at room temperature, which is the relative permittivity _of a pure PbTiO3 single crystal. 1.5 times the constant technique.

In the piezoelectric film containing lead titanate zirconate, when the quality such as crystallinity of the piezoelectric film is not good, the piezoelectric properties of the piezoelectric film are degraded. On the other hand, when the crystallinity of the piezoelectric film is good, the piezoelectric properties of the piezoelectric film are improved, and the relative permittivity of the piezoelectric film does not decrease. For example, when the piezoelectric film is used as a pressure sensor When the pressure sensor is used, for example, the capacity of the pressure sensor increases, the detection sensitivity of the pressure sensor decreases, and the design of the detection circuit of the pressure sensor may become difficult.

However, it is difficult to form a piezoelectric film of lead zirconate titanate having such good quality such as crystallinity using the conventional film forming apparatus.

[Prior Art Literature]

[Patent Document 1] International Publication No. 2016/009698

[Patent Document 2] Japanese Patent Laid-Open No. 2014-84494

[Non-Patent Document 1] S. Yoshida et al., “Fabrication and characterization of large figure-of-merit epitaxial PMnN-PZT/Si transducer for piezoelectric MEMS sensors”, Sensors and Actuators A 239 (2016) 201-208

[Non-Patent Document 2] Xiaozhou Text, 1 other person, "Growing and Evaluation of PbTiO3 Single Crystal Based on MgO Single Crystal Crucible", Journal of the Kiln Industry Association, 1987, Vol. 95, No. 11, _p.1053 -1058

In one aspect of the present invention, an object of the present invention is to provide a film-forming apparatus or a film-forming method for forming a film with good crystallinity.

Hereinafter, various aspects of the present invention will be described.

A film forming apparatus comprising: a vacuum chamber electrically connected to a ground potential, a target disposed in the vacuum chamber, a power supply unit for supplying high-frequency power to the target, and a gas supply for supplying gas into the vacuum chamber part, an insulating substrate holding part arranged in the vacuum chamber to hold the substrate facing the target, a conductive support part supporting the insulating substrate holding part, arranged in the conductive support part and the vacuum chamber The first insulating member between the two; the conductive support portion is electrically floated to the vacuum chamber by the first insulating member, and the substrate is held by the outer peripheral portion of the substrate in contact with the insulating substrate holding portion. The insulating substrate holding portion is held by the insulating substrate holding portion, the substrate is electrically floating with respect to the conductive support portion, and the insulating substrate holding portion does not overlap with the central portion of the substrate in a plan view.

According to the film forming apparatus of the aforementioned [1], the insulating substrate holding portion is supported by the conductive support portion in an electrically floating state with respect to the vacuum chamber, and the insulating substrate holding portion is held in the vacuum chamber. The substrate of the insulating substrate holding portion is in an electrically floating state with respect to the conductive support portion, so that charges accumulated on the substrate during film formation do not escape to the ground potential. Thereby, a large amount of electric charges can be accumulated on the substrate, and as a result, a film with good crystallinity can be formed.

The film forming apparatus according to the aforementioned [1], further comprising a conductive anti-adhesion plate disposed between the target and the substrate at a distance of within 30 mm from the substrate, and the conductive anti-adhesion plate is oriented to the vacuum chamber. Electrically floating state.

According to the film forming apparatus of the above [2], even if the conductive anti-adhesion plate is arranged on the substrate within a distance of 30 mm, by making the conductive anti-adhesion plate in an electrically floating state with respect to the vacuum chamber, accumulation during film formation can be made. The charge on the substrate does not escape to the ground potential.

The film forming apparatus according to the above [2], wherein the conductive anti-adhesion plate is water-cooled.

The film-forming apparatus of the said [2] or [3] which has the 2nd insulating member arrange|positioned between the said vacuum chamber and the said electroconductive adhesion prevention board.

The film forming apparatus according to any one of the above [1] to [4], wherein the contact area between the substrate and the insulating substrate holding portion is reduced to 20 mm ² or less.

According to the film forming apparatus of the aforementioned [4], by setting the contact area between the substrate and the insulating substrate holding portion to 20 mm ² or less, thermal insulation and electrical insulation to the substrate can be simultaneously obtained.

The film forming apparatus according to any one of the above [1] to [5], wherein a corner of the insulating substrate holding portion has a curved surface.

The film forming apparatus according to any one of the aforementioned [1] to [6], wherein the aforementioned conductive The supporting portion includes a first conductive member supporting the insulating substrate holding portion, the first conductive member is rotatably provided with the insulating substrate holding portion around the first axis, and has a The third insulating member between the first electroconductive member and the insulating substrate holding portion, the film forming apparatus, further includes a rotational driving portion for rotationally driving the first electroconductive member.

The film forming apparatus according to any one of the above [1] to [6], wherein the conductive support portion includes a second conductive member for supporting the insulating substrate holding portion, and the second conductive member is connected to a second axis by a second axis. The first insulating member is interposed between the vacuum chamber and the second conductive member, the second conductive member is in an electrically floating state, and the The film-forming apparatus further includes a rotational driving unit that rotationally drives the second conductive member.

The film forming apparatus according to the aforementioned [7], further comprising a substrate heating unit for heating the substrate, the third insulating member having an enclosing portion enclosing the substrate in a plan view, and the insulating substrate holding portion having an enclosing portion enclosing the substrate in a plan view A plurality of protruding portions each protruding toward the center side of the substrate, and the insulating substrate holding portion holds the substrate in a state in which the outer peripheral portion of the substrate is in contact with each of the plurality of protruding portions.

[10] The film forming apparatus according to any one of the above [1] to [9], comprising a target holding portion for holding the target in the vacuum chamber, and a magnetic field application portion for applying a magnetic field to the target; The horizontal magnetic field on the surface of the target is 140-220G.

[11] The film forming apparatus according to the aforementioned [10], wherein the surface of the aforementioned target is before The magnetic field is along the surface of the target.

[12] The film forming apparatus according to any one of the above [1] to [11], wherein the film forming apparatus forms a titanium zirconium-containing material on the surface of the substrate by sputtering the surface of the target containing lead titanic zirconate. Lead acid film.

[13] The film formation apparatus according to any one of the above [1] to [12], wherein the film formation apparatus is formed on the substrate by sputtering in the vacuum chamber the upper surface of the target disposed opposite to the lower surface of the substrate The film is formed below.

[14] A film forming method, characterized in that in a vacuum chamber electrically connected to a ground potential, an outer peripheral portion of a substrate is in contact with an insulating substrate holding portion, the insulating substrate holding portion holds the substrate, and The surface of the target is sputtered in the vacuum chamber to form a film on the surface of the substrate, the insulating substrate holding portion is supported by a conductive support portion electrically floating with respect to the vacuum chamber, and the substrate is supported by the conductive support The portion is in an electrically floating state, and the insulating substrate holding portion does not overlap with the central portion of the substrate in plan view.

[15] The film forming method according to the aforementioned [14], wherein a conductive anti-adhesion plate is disposed between the target and the substrate, the conductive anti-adhesion plate is positioned within a distance of 30 mm from the substrate, and the conductive anti-adhesion plate is positioned within a distance of 30 mm from the substrate. The attachment plate is electrically floating to the aforementioned vacuum chamber.

[16] The film-forming method according to the aforementioned [14], wherein the conductive anti-adhesion plate is water-cooled.

[17] The film forming method according to any one of the above [14] to [16], wherein the contact area between the substrate and the insulating substrate holding portion is 20 mm ² or less.

[18] The film-forming method according to any one of the aforementioned [14] to [17], wherein the The magnetic field applying unit applies a magnetic field to the target, and in a state where high-frequency power is supplied to the target by the power supply unit, the film is formed on the surface of the substrate by sputtering the surface of the target, and the magnetic field is applied. The horizontal magnetic field on the surface of the target is 140-220G.

[19] The film-forming method according to the aforementioned [18], wherein the magnetic field on the surface of the target is along the surface of the target.

[20] The film forming method according to any one of the aforementioned [14] to [19], wherein the target contains lead zirconate titanate, and the surface of the target is sputtered to form a film containing lead zirconate titanate on the surface of the substrate. the aforementioned film.

[21] The film forming method according to the above [20], wherein the substrate includes a silicon substrate including a main surface formed by a (100) plane, is formed on the main surface, has a cubic crystal structure, and includes A first film of a (100) oriented zirconia film, and a first conductive film formed on the first film, having a cubic crystal structure, and including a (100) oriented platinum film; the zirconia film, with Aligning the <100> direction along the main surface of the zirconia film in parallel with the <100> direction along the main surface of the silicon substrate; and aligning the platinum film along the main surface of the platinum film The <100> direction is aligned parallel to the <100> direction along the main surface of the silicon substrate; by sputtering the surface of the target, a tetragonal crystal structure is formed on the first conductive film , and a first piezoelectric film including a (001)-aligned first lead zirconate titanate film, the first lead zirconate titanate film having a lead zirconate titanate film represented by the following general formula (chemical formula 1) The first composite oxide, Pb(Zr _1-x Ti _x )O ₃ ‧‧‧(Chemical formula 1), the first lead titan zirconate film is formed along the main surface of the first lead titan zirconate film. The 100> direction is aligned parallel to the <100> direction along the main surface of the silicon substrate; the x satisfies 0.32≦x≦0.52.

[22] The film-forming method according to any one of the above [14] to [21], wherein the film is formed on the underside of the substrate by sputtering the topside of the target disposed opposite to the underside of the substrate in the vacuum chamber.

By applying one aspect of the present invention, a film forming apparatus or a film forming method for forming a film with good crystallinity can be provided.

10: Membrane constructs

11: Substrate

11a: Above

12: Alignment film

12a: Zirconia film

13, 18: Conductive film

13a: Platinum film

14, 17f: Membrane

14a: SRO membrane

15, 16, 17: Piezoelectric film

15a, 16a, 17a: lead titanate zirconate film

16g, 17g: grains

20: Film forming device

21: Vacuum Chamber

21a: Bottom plate

21b, 21e: side plate

21c, 21f: top plate

21d: Cover

22: Vacuum exhaust part

23, 24: Gas supply part

23a, 24a: flow controller

23b, 24b: Gas supply pipes

25: Substrate holding part

25a: Insulating enclosure

25b: Protrusion

25c: Conductive enclosure

25d: Step part

25b1: Corner

26: Support Department

27: Rotary drive part

27a: Motor

27b: Belt

27c: Pulley

27d: Rotation axis

28: Substrate heating section

29: Anti-adhesion plate

29a: Cooling pipe

31: Target holding part

32: Power Supply Department

32a: High frequency power supply

32b: Integrator

33: V _DC control part

34: Magnet Department

35: Magnet rotating drive part

41, 42, 45, 46, 47: Conductive members

41a, 42a, 45a: base

41b, 42b, 45b: Shaft

41c, 42c, 45c: Connections

43, 56: Screws

44: Slip Ring

51, 52, 53, 54, 55: Insulating members

BP1: backing plate

CE1: Sealing part

CN1: Center

CP1: ferroelectric capacitor

EP: End Point

OP1, OP2, OP3: Opening

P1: Polarized composition

RA1: Rotary axis

SB: Substrate

SP: starting point

TG: target

TM1: Target

FIG. 1 is a cross-sectional view of a membrane structure of an embodiment.

2 is a cross-sectional view of the film structure in the case where the film structure of the embodiment has a conductive film as the upper electrode.

FIG. 3 is a cross-sectional view of the film structure when the substrate and the alignment film are removed from the film structure shown in FIG. 2 .

4 is a cross-sectional view of another example of the membrane structure of the embodiment.

FIG. 5 is a diagram schematically showing a cross-sectional structure of two piezoelectric films included in the film structure of the embodiment.

FIG. 6 is a diagram schematically showing the electric field dependence of the polarization of the piezoelectric film included in the film structure of the embodiment.

7 is a diagram illustrating a state of film epitaxial growth of each layer included in the film structure of the embodiment.

FIG. 8 is a cross-sectional view schematically showing a film forming apparatus of an embodiment.

FIG. 9 is a cross-sectional view schematically showing the film forming apparatus of the embodiment.

FIG. 10(A) shows the substrate holding portion included in the film forming apparatus of the embodiment. 10(B) to (D) are plan views showing the shape of the protruding portion 25b shown in FIG. 10(A).

Fig. 11 is a cross-sectional view in a manufacturing step of the film structure of the embodiment.

Fig. 12 is a cross-sectional view in a manufacturing step of the film structure of the embodiment.

FIG. 13 is a cross-sectional view in a manufacturing step of the film structure of the embodiment.

FIG. 14 is a cross-sectional view in a manufacturing step of the membrane structure of the embodiment.

15 is a cross-sectional view of a membrane structure according to a modification of the embodiment.

16 is a diagram showing an example of the θ-2θ spectrum of the film structure of Example 1 according to the XRD method.

FIG. 17 is a diagram showing an example of the θ-2θ spectrum by the XRD method of the film structure of Example 1. FIG.

18 is a diagram showing an example of the θ-2θ spectrum of the film structure of Comparative Example 1 according to the XRD method.

FIG. 19 is a diagram showing an example of the θ-2θ spectrum by the XRD method of the film structure of Comparative Example 1. FIG.

FIG. 20 is a diagram showing an example of a pole diagram according to the XRD method of the film structure of Example 1. FIG.

FIG. 21 is a diagram showing an example of a pole diagram according to the XRD method of the film structure of Example 1. FIG.

FIG. 22 is a diagram showing an example of a pole diagram according to the XRD method of the film structure of Example 1. FIG.

23 is a diagram showing an example of a pole diagram according to the XRD method of the film structure of Example 1. FIG.

24 is a diagram showing the diffraction angle 2θ ₀₀₄ of each X-ray diffraction pattern of the film structures formed on each of the 17 wafers of Example 1. FIG.

FIG. 25 is a diagram showing the diffraction angle 2θ ₀₀₄ of each X-ray diffraction pattern of the film structures formed on each of the 12 wafers of Example 1. FIG.

FIG. 26 is a graph showing the voltage dependence of polarization of the membrane structure of Example 1. FIG.

FIG. 27 is a graph showing the voltage dependence of polarization of the membrane structure of Comparative Example 1. FIG.

FIG. 28 is a graph showing the voltage dependence of polarization of the membrane structure of Example 2. FIG.

FIG. 29 is a graph showing the voltage dependence of polarization of the membrane structure of Example 3. FIG.

FIG. 30 is a graph showing the voltage dependence of polarization of the membrane structure of Example 4. FIG.

FIG. 31 is a graph showing the voltage dependence of polarization of the membrane structure of Example 5. FIG.

32 is a table showing the measurement results of the film formation conditions of Example 1, Example 6 to Example 8, Comparative Example 1 and Comparative Example 2, and the diffraction angle 2θ ₀₀₄ and relative permittivity ε _r of PZT.

FIG. 33 is a diagram showing an example of the θ-2θ spectrum according to the XRD method of the film structure of Example 6. FIG.

34 is a diagram showing an example of the θ-2θ spectrum of the film structure of Example 7 according to the XRD method.

35 is a diagram showing an example of the θ-2θ spectrum according to the XRD method of the film structure of Example 8. FIG.

FIG. 36 is a graph showing the voltage dependence of polarization of the membrane structure of Comparative Example 2. FIG.

FIG. 37 is a graph showing the voltage dependence of polarization of the membrane structure of Example 6. FIG.

FIG. 38 is a graph showing the voltage dependence of polarization of the membrane structure of Example 7. FIG.

FIG. 39 is a graph showing the voltage dependence of polarization of the membrane structure of Example 8. FIG.

FIG. 40 is a graph showing the voltage dependence of polarization of the membrane structure of Example 9. FIG.

FIG. 41 is a graph showing the voltage dependence of polarization of the membrane structure of Example 10. FIG.

Hereinafter, embodiments and examples of the present invention will be described in detail using the drawings. However, the present invention is not limited to the following description, and various changes can be made to its form or detailed content without departing from the gist and scope of the present invention, which should be easily understood by those skilled in the art range. Therefore, the present invention is not to be construed as being limited to the descriptions and examples of the embodiments shown below.

In addition, the drawings can make the description more clear, and when the width, thickness, shape, etc. of each part are schematically shown compared with the embodiment, it is only an example after all, and is not intended to limit the present invention. explain.

In addition, in this specification and each drawing, with respect to what has been shown and the previous The same elements are given the same symbols, and detailed descriptions are appropriately omitted.

Furthermore, depending on the drawings used in the embodiments, hatching (network lines) provided for distinguishing structures may be omitted in accordance with the drawings.

In addition, in the following embodiment, when the range is shown by A to B, it means A or more and B or less unless otherwise specified.

(implementation type) <Membrane structure>

First, the membrane structure of the embodiment of one embodiment of the present invention will be described. FIG. 1 is a cross-sectional view of a membrane structure of an embodiment. 2 is a cross-sectional view of the film structure in the case where the film structure of the embodiment has a conductive film as the upper electrode. FIG. 3 is a cross-sectional view of the film structure when the substrate and the alignment film are removed from the film structure shown in FIG. 2 . 4 is a cross-sectional view of another example of the membrane structure of the embodiment.

As shown in FIG. 1 , the film structure 10 of this embodiment includes a substrate 11 , an alignment film 12 , a conductive film 13 , a film 14 , and a piezoelectric film 15 . The alignment film 12 is formed on the substrate 11 . The conductive film 13 is formed on the alignment film 12 . The film 14 is formed on the conductive film 13 . The piezoelectric film 15 is formed on the film 14 .

Moreover, as shown in FIG. 2, the film structure 10 of this embodiment may have the conductive film 18. The conductive film 18 is formed on the piezoelectric film 15 . At this time, the conductive film 13 is used as the conductive film of the lower electrode, and the conductive film 18 is used as the conductive film of the upper electrode. In addition, as shown in FIG. 3 , the film structure 10 of this embodiment may not include the substrate 11 (see FIG. 2 ) and the alignment film 12 (see FIG. 2 ), but only include the conductive film 13 and the film as the lower electrode. 14. Press The electric film 15, and the conductive film 18 as the upper electrode.

In addition, as shown in FIG. 4 , the film structure 10 of the present embodiment may only have the substrate 11 , the alignment film 12 , and the conductive film 13 . In such a case, the film structure 10 can be used as an electrode substrate for forming the piezoelectric film 15, epitaxial growth can be performed on the conductive film 13, and the piezoelectric film 15 having good piezoelectric properties can be easily formed.

The substrate 11 is a silicon substrate made of silicon (Si) single crystal. The substrate 11, which is a silicon substrate, includes the upper surface 11a of the main surface constituted by the (100) plane. The alignment film 12 is formed on the upper surface 11a, has a cubic crystal structure, and includes (100) oriented zirconia. The conductive film 13 has a cubic crystal structure and contains (100) oriented platinum. Accordingly, when the piezoelectric film 15 includes a composite oxide having a perovskite type structure, the piezoelectric film 15 can have a (001) orientation represented by a tetragonal crystal on the substrate 11 or a The (100) orientation represented by quasi-cubic crystals.

Here, that the alignment film 12 is (100) aligned means that the (100) plane of the alignment film 12 having a cubic crystal structure is along the main surface of the substrate 11 of the silicon substrate, which is constituted by the (100) plane. The upper surface 11a is preferably the upper surface 11a formed by the (100) plane of the substrate 11 parallel to the silicon substrate. In addition, the upper surface 11a formed by the (100) plane of the alignment film 12 being parallel to the (100) plane of the substrate 11 refers not only to the case where the (100) plane of the alignment film 12 is completely parallel to the upper surface 11a of the substrate 11, but also includes When the angle between the surface completely parallel to the upper surface 11a of the substrate 11 and the (100) surface of the alignment film 12 is 20° or less. In addition, not only the alignment film 12, but also the alignment of the films of other layers is the same.

Alternatively, instead of the alignment film 12 composed of a single-layer film, the alignment film 12 composed of a laminated film may be formed on the substrate 11 as the alignment film 12 .

Preferably, the alignment film 12 is epitaxially grown on the upper surface 11 a of the substrate 11 , and the conductive film 13 is epitaxially grown on the alignment film 12 . Thereby, when the piezoelectric film 15 includes a complex oxide having a perovskite type structure, the piezoelectric film 15 can be epitaxially grown on the conductive film 13 .

Here, when two directions orthogonal to each other in the upper surface 11a serving as the main surface of the substrate 11 are defined as the X-axis direction and the Y-axis direction, and the direction perpendicular to the upper surface 11a is defined as the Z-axis direction, a certain film is epitaxially grown. , means that the film is oriented in any one of the X-axis direction, the Y-axis direction, and the Z-axis direction. In addition, the suitable orientation direction in the upper surface 11a is demonstrated using FIG. 7 mentioned later.

The film 14 is represented by the following general formula (Chemical Formula 4) and includes a composite oxide represented by a quasi-cubic crystal with a (100) orientation.

Sr(Ti _1-z Ru _z )O ₃ ‧‧‧(Chemical formula 4)

Here, z satisfies 0≦z≦1. In addition, in the following, Sr(Ti _1-z Ru _z )O ₃ or SrTiO ₃ when z satisfies z=0 is also called STO, and Sr(Ti _1-z Ru 3 when z satisfies 0<z<1 _z )O ₃ is called STRO, and Sr(Ti _1-z Ru _z )O ₃ when z satisfies z=1, that is, SrRuO ₃ is called SRO.

SRO has metallic conductivity and STO has semiconducting or insulating properties. Therefore, as z is closer to 1, the conductivity of the film 14 is improved, and the film 14 can be used as a part of the lower electrode including the conductive film 13 .

Here, when the film 14 is formed by the sputtering method, z satisfies 0≦z≦0.4 is preferable, and 0.05≦z≦0.2 is more preferable. When z exceeds 0.4, the composite oxide represented by the aforementioned general formula (Chemical formula 4) becomes powder, and there is a possibility that it cannot be sufficiently cured, and it becomes difficult to manufacture a sputtering target.

On the other hand, when the film 14 is formed by a coating method such as a sol-gel method, it can be easily formed even if z>0.4.

The composite oxide having a perovskite (perovskite) type structure represented by the aforementioned general formula (Chemical formula 4) is represented by a pseudo-cubic crystal as (100) orientation, which means the following cases.

First, a perovskite (perovskite) structure lattice represented by the general formula ABO ₃ , including a unit lattice arranged in a 3-dimensional dimension, considers that the unit lattice contains one atom A, one atom B and three oxygen atoms atomic case.

In such a case, the (100) orientation represented by the pseudo-cubic crystal means that the unit cell has a cubic crystal structure and the (100) orientation. In this case, the length of one side of the unit lattice is taken as the lattice constant a _c .

On the other hand, consider the case where the composite oxide having a perovskite (perovskite) type structure represented by the aforementioned general formula (Chemical formula 4) has an orthorhombic crystal structure. Next, consider that the first lattice constant a _o among the three lattice constants of the orthorhombic crystal is approximately equal to 2 ^1/2 times the lattice constant a _c of the quasi-cubic crystal, and the three lattice constants of the orthorhombic crystal are The second lattice constant b _o is approximately equal to twice the lattice constant a _c of the quasi-cubic crystal, and the third lattice constant c _o of the three lattice constants of the orthorhombic crystal is approximately equal to the quasi-cubic crystal When the lattice constant a _c of the crystal is 2 ^1/2 times. In addition, in this specification, the numerical value V1 and the numerical value V2 are approximately equal, and the ratio of the difference between the index value V1 and the numerical value V2 is about 5% or less with respect to the average of the numerical value V1 and the numerical value V2.

In this case, the pseudo-cubic crystal is expressed as (100) orientation, which means that the orthorhombic crystal is expressed as (101) orientation or (020) orientation.

Since the film 14 is represented by the aforementioned general formula (chemical formula 4) and satisfies 0≦z≦1, the lattice constant a _c of the quasi-cubic crystal satisfies 0.390 nm≦ _ac ≦0.393 nm, as will be explained using FIG. 7 described later , the film 14 can be (100) oriented on the conductive film 13 in a quasi-cubic representation.

The piezoelectric film 15 has a tetragonal crystal structure formed on the conductive film 13 with an intermediate film 14 interposed therebetween, and contains lead zirconate titanate (PZT) as a (001) oriented complex oxide. Alternatively, when the lead zirconate titanate (PZT) contained in the piezoelectric film 15 includes a portion having a tetragonal crystal structure and a portion having a rhombohedral crystal structure, the piezoelectric film 15 is interposed by the intervening film 14 It may be formed on the conductive film 13, and may contain lead zirconate titanate (PZT) as a composite oxide expressed as a (100) orientation in a quasi-cubic crystal.

The piezoelectric film 15 contains lead zirconate titanate (PZT), which means that the piezoelectric film 15 contains a complex oxide represented by the following general formula (Chemical Formula 5).

Pb(Zr _1-u Ti _u )O ₃ ‧‧‧(Chemical formula 5)

u satisfies 0<u<1.

In addition, the piezoelectric film 15 has a tetragonal crystal structure, and in the case of including (001)-oriented lead titanate zirconate, in this embodiment, the piezoelectric film 15 is formed by the θ-2θ method using CuKα lines. When the diffraction angle of the diffraction peak of the (004) plane represented by the tetragonal crystal of lead titanate zirconate is 2θ ₀₀₄ , 2θ ₀₀₄ satisfies the following formula (Equation 1).

2θ ₀₀₄ ≦96.5°‧‧‧(Formula 1)

Thereby, the space|interval of the (004) plane represented by the tetragonal crystal of lead titanate zirconate becomes long. Alternatively, the piezoelectric film 15 has a tetragonal crystal structure and the content rate of lead titanate zirconate in a (001) orientation (c-axis orientation) may be higher than that in the piezoelectric film 15 with a tetragonal crystal structure, and ( The content of lead titanate zirconate in 100) orientation (a-axis orientation) is even larger. That is, the polarization directions of each of the plurality of crystal grains included in the piezoelectric film 15 can be aligned, so that the piezoelectric properties of the piezoelectric film 15 can be improved.

On the other hand, the case where the piezoelectric film 15 includes lead zirconate titanate (PZT) having a (100) orientation in a quasi-cubic crystal can be considered as follows.

The lead titanate zirconate contained in the piezoelectric film 15 has a tetragonal crystal structure. The two lattice constants of the tetragonal crystal are at and c _t , and at and _{c t satisfy} c _t >at _, and the unit lattice _is considered When the lengths of the three _{mutually orthogonal sides are at, at, and ct of} a _cube . Next, consider the case where the lattice constant at _t of the tetragonal crystal is approximately equal to the lattice constant a _c of the quasi-cubic crystal, and the lattice constant c _t of the tetragonal crystal is approximately equal to the lattice constant a _c of the quasi-cubic crystal. In such a case, the lead zirconate titanate has a (100) orientation in the quasi-cubic crystal, which means that the lead titan zirconate has a (100) orientation (a-axis orientation) or a (001) orientation (c-axis orientation) in a tetragonal crystal. .

On the other hand, consider the case where the PZT included in the piezoelectric film 15 has a crystal structure of a _rhombohedral crystal, and the lattice constant of the rhombohedral crystal is ar. Next, consider the case where the lattice constant a _r of the rhombohedral crystal is approximately equal to the lattice constant a _c of the quasi-cubic crystal. In such a case, the PZT has a (100) orientation in a quasi-cubic crystal, which means that the PZT has a (100) orientation in a rhombohedral crystal.

In this case, in this embodiment, the diffraction peak of the (400) plane represented by the quasi-cubic crystal of lead zirconate titanate is shown in the X-ray diffraction pattern of the piezoelectric film 15 by the θ-2θ method using CuKα line. When the diffraction angle is 2θ ₄₀₀ , 2θ ₄₀₀ satisfies the aforementioned formula (Equation 1), and satisfies the formula (2θ ₄₀₀ ≦96.5°) that replaces 2θ ₀₀₄ with 2θ ₄₀₀ . Next, by this, the interval of the (400) plane represented by the quasi-cubic crystal of lead titanate zirconate becomes longer. Therefore, the content rate of lead titanate zirconate in the piezoelectric film 15 having a tetragonal crystal structure and (001) alignment can be higher than that of the piezoelectric film 15 having a tetragonal crystal structure and (100) alignment titanium The content of lead zirconate is even larger. That is, the polarization directions of each of the plurality of crystal grains included in the piezoelectric film 15 can be aligned, so that the piezoelectric properties of the piezoelectric film 15 can be improved.

In addition, in this embodiment, when the relative permittivity of the piezoelectric film 15 is ε _r , ε _r satisfies the following equation (Equation 2).

ε _r ≦450‧‧‧ (Equation 2).

Thereby, when the membrane structure 10 is used as a pressure sensor using a piezoelectric effect, for example, the detection sensitivity can be improved, and the detection circuit of the pressure sensor can be easily designed. Alternatively, when the membrane structure 10 is used, for example, as an ultrasonic vibrator using an inverse piezoelectric effect, an oscillation circuit can be easily designed.

For a film structure having a piezoelectric film containing lead zirconate titanate, for example, due to a low film density or a small content of lead zirconate titanate, when the quality of the piezoelectric film such as crystallinity is not good, the piezoelectric film piezoelectric properties will be reduced. On the other hand, in the case of a film structure having a piezoelectric film containing lead zirconate titanate, for example, for reasons such as high film density or high content of lead zirconate titanate, the quality of the piezoelectric film such as crystallinity is good. The piezoelectric properties of the piezoelectric film will be improved, while The relative permittivity of the piezoelectric film is not small.

In this way, when the piezoelectric properties of the piezoelectric film are improved in the film structure having the piezoelectric film containing lead titanate zirconate, the relative permittivity of the piezoelectric film may not be small. Next, if the relative permittivity of the piezoelectric film does not decrease, for example, when the piezoelectric film is used as a pressure sensor, for example, the capacity of the pressure sensor increases, and the pressure sensor The detection sensitivity of the pressure sensor decreases, and the design of the detection circuit of the pressure sensor may become difficult.

In the membrane structure 10 of the present embodiment, 2θ ₀₀₄ satisfies the aforementioned formula (Equation 1), and ε _r satisfies the aforementioned formula (Equation 2). By making 2θ ₀₀₄ satisfy the aforementioned formula (Equation 1), the piezoelectric film 15 can have a tetragonal crystal structure, and the content of lead zirconate titanate in the (001) orientation can be increased, so that it is possible to increase Piezoelectric properties. . In addition, since ε _r satisfies the aforementioned formula (Equation 2), the relative permittivity becomes small, so that the detection sensitivity of the pressure sensor can be increased. That is, according to the film structure 10 of the present embodiment, the piezoelectric characteristics can be improved, and the detection sensitivity of the sensor using the piezoelectric effect can be improved. That is, in the film structure having the piezoelectric film containing lead titanate zirconate, the piezoelectric properties of the piezoelectric film can be improved, and the detection sensitivity of the pressure sensor using the piezoelectric film can be improved.

As described in the aforementioned Non-Patent Document 2, PbTiO ₃ is in a single crystal form, and when crystallinity including orientation and the like is improved, the relative permittivity is lowered. That is, PZT, like PbTiO ₃ , improves the crystallinity including the orientation of the thin film, so that the relative permittivity becomes low. That is, when the relative permittivity ε _r of the film structure 10 is as low as 450 or less, it is shown that the piezoelectric film 15 including the piezoelectric film of lead titanate zirconate becomes a single crystal.

Suitably, when the film structure 10 has the conductive film 18, when the relative permittivity of the piezoelectric film 15 measured by applying an alternating voltage with a frequency of 1 kHz between the conductive film 13 and the conductive film 18 is _εr , the pressure ε _r of the electric film 15 satisfies the aforementioned formula (Equation 2). By reducing the relative permittivity under an AC voltage having such a frequency, for example, the clock frequency of the detection circuit can be increased, and the response speed of the pressure sensor using the membrane structure 10 can be improved.

When the film structure 10 has the conductive film 18 , the ferroelectric capacitor CP1 is formed by the conductive film 13 , the conductive film 15 , and the conductive film 18 . Next, ε _r of the piezoelectric film 15 is calculated from the electrostatic capacitance of the ferroelectric capacitor CP1 when an AC voltage having a frequency of 1 kHz is applied between the conductive film 13 and the conductive film 18 .

Suitably, when the residual extreme value of the piezoelectric film 15 is _Pr , _Pr satisfies the following formula (Equation 3).

P _r ≧28μC/cm ² ‧‧‧(Equation 3)

The residual extreme value is a value that serves as an index of the ferroelectric properties of a piezoelectric body that is also a ferroelectric material. Generally, a piezoelectric film having excellent ferroelectric properties also has excellent piezoelectric properties. That is, since P _r of the piezoelectric film 15 satisfies the aforementioned formula (Equation 3), the ferroelectric properties of the piezoelectric film 15 can be improved, so that the piezoelectric properties of the piezoelectric film 15 can also be improved.

In addition, it is preferable that _Pr satisfies _{Pr ≧} 40 μC/cm ² , more preferably _Pr ≧ 50 μC/cm ² , and even more preferably Pr ≧ 55 μC/cm ² . The larger the _Pr , the more the ferroelectric properties of the piezoelectric film 15 can be improved, so the piezoelectric properties of the piezoelectric film 15 can be further improved.

When the film structure 10 has the conductive film 18, a polarization voltage hysteresis curve (refer to FIG. 6 described later) showing the polarization change of the piezoelectric film 15 when the voltage applied between the conductive film 13 and the conductive film 18 is changed is measured. , the polarization value when the voltage applied between the conductive film 13 and the conductive film 18 increases from 0 to the positive side and returns to 0 again is the residual polarization value _Pr of the piezoelectric film 15 . In addition, the extreme value when the voltage applied between the conductive film 13 and the conductive film 18 decreases from 0 to the negative side and returns to 0 again is the residual extreme value of the piezoelectric film 15 -P _r .

That is, when measuring the polarization electric field hysteresis curve showing the polarization change of the piezoelectric film 15 when the electric field applied to the piezoelectric film 15 is changed, the voltage applied to the piezoelectric film 15 is increased from 0 to the positive side and then returned to The polarization at 0 is the residual polarization value P _r of the piezoelectric film 15 . In addition, the polarization when the electric field applied to the piezoelectric film 15 decreases from 0 to the negative side and returns to 0 again is the residual polarization value -P _r of the piezoelectric film 15 .

As shown in FIG. 2 , when the film structure 10 includes the conductive film 18 , the ferroelectric capacitor CP1 is formed by the conductive film 13 , the conductive film 15 , and the conductive film 18 . In such a case, Pr of the piezoelectric film 15 is the residual extreme value of the ferroelectric capacitor _CP1 .

Suitably, the piezoelectric film 15 includes the piezoelectric film 16 and the piezoelectric film 17 . The piezoelectric film 16 contains a composite oxide composed of lead zirconate titanate formed on the film 14 . The piezoelectric film 17 includes a composite oxide composed of lead zirconate titanate formed on the piezoelectric film 16 . The piezoelectric film 16 has compressive stress, and the piezoelectric film 17 has tensile stress.

Considering that the piezoelectric film 16 has tensile stress, and the piezoelectric film 17 has tensile stress the occasion. In such a case, when the film structure 10 has the upper surface 11 a of the substrate 11 as its main surface, it is likely to be warped so as to have a downwardly protruding shape. Therefore, for example, when the film structure 10 is processed by the photolithography technique, the shape accuracy is lowered, and the properties of the piezoelectric element formed by processing the film structure 10 are also lowered.

Also, consider a case where the piezoelectric film 16 has compressive stress and the piezoelectric film 17 has compressive stress. In such a case, when the film structure 10 has the upper surface 11a of the substrate 11 as its main surface, it is liable to warp so as to have a shape protruding upward. Therefore, for example, when the film structure 10 is processed by the photolithography technique, the shape accuracy is lowered, and the properties of the piezoelectric element formed by processing the film structure 10 are also lowered.

On the other hand, in this embodiment, the piezoelectric film 16 has compressive stress, and the piezoelectric film 17 has tensile stress. This makes it possible to reduce the warpage amount of the warpage of the film structure 10 compared with the case where both the piezoelectric film 16 and the piezoelectric film 17 have tensile stress. The warpage amount of the film structure 10 can be reduced compared to the case where any one has compressive stress. Therefore, for example, when the film structure 10 is processed by the photolithography technique, the shape accuracy can be improved, and the properties of the piezoelectric element formed by processing the film structure 10 can be improved.

Further, that the piezoelectric film 16 has compressive stress and the piezoelectric film 17 has tensile stress means that, for example, when the piezoelectric film 17 and the piezoelectric film 16 are sequentially removed from the film structure 10, the piezoelectric film Before and after the removal of 17, the substrate 11 was deformed from the convex side below to the convex side above, and before and after the removal of the piezoelectric film 16, the substrate 11 was confirmed to be deformed from the convex side above to the convex side below.

Suitably, the piezoelectric film 16 contains a composite oxide composed of lead zirconate titanate (PZT) represented by the following general formula (Chemical Formula 6).

Pb(Zr _1-x Ti _x )O ₃ ‧‧‧(Chemical formula 6)

Here, x satisfies 0.32≦x≦0.52.

Among them, when x satisfies 0.32≦x≦0.48, the PZT included in the piezoelectric film 16 has a crystal structure of rhombohedral crystals that should be originally composed of tetragonal crystals mainly due to the binding force from the substrate 11 or the like. structure, and easy to (001) alignment. Next, the piezoelectric film 16 containing PZT is epitaxially grown on the film 14 . In addition, when x satisfies 0.48<x≦0.52, the PZT included in the piezoelectric film 16 has a tetragonal crystal structure because of its composition, and has a tetragonal crystal structure and has a (001) orientation. Next, the piezoelectric film 16 containing PZT is epitaxially grown on the film 14 . Thereby, the direction of the polar axis of the lead zirconate titanate contained in the piezoelectric film 16 can be aligned approximately perpendicular to the upper surface 11a, so that the piezoelectric properties of the piezoelectric film 16 can be improved.

Further, it is appropriate that the piezoelectric film 17 contains a composite oxide composed of lead zirconate titanate (PZT) represented by the following general formula (Chemical formula 7).

Pb(Zr _1-y Ti _y )O ₃ ‧‧‧(Chemical formula 7)

Here, y satisfies 0.32≦y≦0.52.

Among them, when y satisfies 0.32≦y≦0.48, the PZT included in the piezoelectric film 17 has a crystal structure of rhombohedral crystals that should be originally composed of tetragonal crystals mainly due to the restraint force from the substrate 11 or the like. structure, and easy to (001) alignment. Next, the piezoelectric film 17 containing PZT is epitaxially grown on the piezoelectric film 16 . In addition, when y satisfies 0.48<y≦0.52, the PZT included in the piezoelectric film 17 has a tetragonal crystal structure originally. Due to the composition, it has a tetragonal crystal structure and has a (001) orientation. Next, the piezoelectric film 17 containing PZT is epitaxially grown on the piezoelectric film 16 . Thereby, the direction of the polar axis of the lead zirconate titanate contained in the piezoelectric film 17 can be aligned approximately perpendicular to the upper surface 11a, so that the piezoelectric characteristics of the piezoelectric film 17 can be improved.

The piezoelectric film 16 having compressive stress can be formed by, for example, a sputtering method, as described with reference to FIG. 14 to be described later. In addition, when the manufacturing procedure of a film structure is demonstrated, as demonstrated using later-mentioned FIG. 1, the piezoelectric film 17 which has tensile stress can be formed by coating methods, such as a sol-gel method, for example.

FIG. 5 is a diagram schematically showing a cross-sectional structure of two piezoelectric films included in the film structure of the embodiment. FIG. 5 is an observation of a cross section formed by cleaving the substrate 11 included in the film structure 10 of the embodiment shown in FIG. 1 , that is, observation of a fractured section with a Scanning Electron Microscope (SEM) In the video, the piezoelectric film 16 and the piezoelectric film 17 are schematically displayed.

FIG. 6 is a diagram schematically showing the electric field dependence of the polarization of the piezoelectric film included in the film structure of the embodiment. FIG. 6 schematically shows polarization of the piezoelectric film 15 when an electric field is applied between the lower electrode (conductive film 13 ) and the upper electrode (conductive film 18 ) of the film structure 10 of the embodiment shown in FIG. 2 . Plot of the hysteresis curve of the changing polar electric field.

As shown in FIG. 5 , when the piezoelectric film 16 is formed by sputtering, the piezoelectric film 16 includes a plurality of crystal grains 16 g integrally formed from the lower surface to the upper surface of the piezoelectric film 16 . In addition, in the main surface of the substrate 11 (the upper surface 11a in FIG. 1 ), between the two crystal grains 16g adjacent to each other, voids or holes are not easily left. void. Therefore, when the piezoelectric film 16 is processed by the Focused Ion Beam (FIB) method to form a cross-section for observation in the SEM, the cross-section is easily seen as a single cross-section, and the crystal grains 16g are difficult to be separated from each other. observed.

On the other hand, when the piezoelectric film 17 is formed by a coating method, the piezoelectric film 17 includes a plurality of films 17f in which a plurality of layers are stacked on each other in the thickness direction of the piezoelectric film 17 . The film 17f as each of the plural layers includes plural crystal grains 17g integrally formed from the lower surface to the upper surface of the single-layered film 17f. In addition, voids or voids remain between the two-layer films 17f adjacent to each other in the thickness direction of the piezoelectric film 17 .

As shown in FIG. 5, it is appropriate that each of the plurality of grains has spontaneous polarization. This spontaneous polarization includes the polarization component P1 parallel to the thickness direction of the piezoelectric film 16 and the polarization component P1 included in the spontaneous polarization of each of the plurality of crystal grains, which are oriented in the same direction.

In such a case, as shown in FIG. 6 , in the initial state, the piezoelectric film 15 has a large spontaneous polarization. Therefore, when the electric field is increased to the positive side from the starting point SP where the electric field is 0 and returns to 0 again, and the electric field is decreased to the negative side and returns to the end point EP of 0 again, the electric field dependence of the polarization of the piezoelectric film 15 is shown. The hysteresis curve shows the curve from the point away from the origin as the starting point SP. That is, when the film structure 10 of the present embodiment is used as a piezoelectric element, it is not necessary to perform polarizing treatment on the piezoelectric film 15 before use.

This should be so that the piezoelectric film 15 has a large spontaneous polarization in the initial state. For example, when the piezoelectric film 16 is formed using a film forming apparatus as an RF sputtering apparatus described with reference to FIGS. 8 to 10 , the electrical pulp or electrons, not allowed It is easily affected by the ground potential (zero potential), and a large amount of electric charge can be accumulated on the substrate by being stably enclosed between the target and the substrate.

7 is a diagram illustrating a state of film epitaxial growth of each layer included in the film structure of the embodiment. 7, the layers of the substrate 11, the alignment film 12, the conductive film 13, the film 14, and the piezoelectric film 15 are schematically shown.

The lattice constant of silicon included in the substrate 11 , the lattice constant of ZrO ₂ included in the alignment film 12 , the lattice constant of Pt included in the conductive film 13 , the lattice constant of SRO included in the film 14 , and Table 1 shows the lattice constants of PZT of the piezoelectric film 15 .

As shown in Table 1, the lattice constant of Si is 0.543 nm, the lattice constant of ZrO ₂ is 0.511 nm, and the unconformity of the lattice constant of ZrO ₂ with respect to the lattice constant of Si is relatively small at 6.1%. The conformity of the lattice constant of ZrO ₂ with respect to the lattice constant of Si is good. Therefore, as shown in FIG. 7 , the alignment film 12 containing ZrO ₂ can be epitaxially grown on the upper surface 11 a which is the main surface constituted by the (100) surface of the substrate 11 including the silicon single crystal. That is, the alignment film 12 containing ZrO ₂ can have a (100) orientation with a cubic crystal structure on the (100) surface of the substrate 11 containing silicon single crystal, and the crystallinity of the alignment film 12 can be improved.

The alignment film 12 has a cubic crystal structure, and includes a (100) alignment zirconia film 12a. In such a case, the zirconium oxide film 12a is in the <100> direction along the upper surface 11a of the main surface of the substrate 11 composed of the silicon substrate of the zirconia film 12a and the <100> direction of the upper surface 11a of the substrate 11 itself. Align in parallel.

In addition, the <100> direction of the zirconia film 12a along the upper surface 11a of the substrate 11 is parallel to the <100> direction of the upper surface 11a of the substrate 11 itself composed of the silicon substrate, and not only the <100> direction of the zirconia film 12a is included When the > direction is completely parallel to the <100> direction along the upper surface 11a of the substrate 11 itself, the angle between the <100> direction of the zirconia film 12a and the <100> direction along the upper surface 11a of the substrate 11 itself is 20° ° or less. In addition, not only the zirconia film 12a but also the in-plane alignment of the films of other layers is the same.

On the other hand, as shown in Table 1, the lattice constant of ZrO ₂ is 0.511 nm, the lattice constant of Pt is 0.392 nm, and when Pt is rotated by 45° in the plane, the length of the diagonal becomes 0.554 nm, Since the unconformity of the diagonal length with respect to the lattice constant of ZrO ₂ is relatively small at 8.1%, the conductive film 13 containing Pt can be formed on the (100) plane of the alignment film 12 containing ZrO ₂ Epitaxy growth. For example, in the aforementioned Patent Document 2 and the aforementioned Non-Patent Document 1, it is reported that not a Pt film but a LSCO film composed of LSCO having a lattice constant (0.381 nm) approximately the same as that of Pt. The 100> direction is aligned parallel to the <110> direction in the main surface of the silicon substrate.

However, the inventors of the present application first discovered that the unconformity between the lattice constant of Pt and the lattice constant of ZrO ₂ is as high as 26%, but if the Pt is not rotated by 45° in the plane, the conductive film 13 containing Pt can be formed in the silicon Epitaxial growth on the substrate. That is, the conductive film 13 has a cubic crystal structure and includes the platinum film 13a of the (100) orientation. In such a case, the platinum film 13a is aligned so as to be parallel to the <100> direction of the upper surface 11a of the upper surface 11a of the substrate 11 composed of the silicon substrate of the platinum film 13a and the <100> direction of the upper surface 11a of the substrate 11 itself. . It can be seen that by doing so, the conductive film 13 containing Pt can be oriented to (100) with a cubic crystal structure on the (100) plane of the alignment film 12 containing ZrO ₂ , and the crystallinity of the conductive film 13 can be improved.

In addition, by adjusting the conditions for forming ZrO ₂ or the conditions for forming Pt, the <100> direction of Pt can be aligned in the state where Pt is rotated by 45° in the plane, that is, in the main surface of the substrate 11 . The conductive film 13 containing Pt is epitaxially grown on the (100) plane of the alignment film 12 containing ZrO ₂ in the state of the <110> direction of Si.

In addition, as shown in Table 1, the lattice constant of Pt is 0.392 nm, the lattice constant of SRO is 0.390 to 0.393 nm, and the unconformity of the lattice constant of PZT with respect to the lattice constant of Pt is 0.5% or less. Since it is small, the integration of the lattice constant of SRO with the lattice constant of Pt is good. Therefore, as shown in FIG. 7, the film 14 containing SRO can be epitaxially grown on the (100) plane of the conductive film 13 containing Pt. That is, the film 14 containing SRO can have a (100) orientation with a cubic crystal structure on the (100) plane of the conductive film 13 containing Pt, and the crystallinity of the film 14 can be improved.

The film 14 has a quasi-cubic crystal structure and includes the (100) oriented SRO film 14a. In such a case, the SRO film 14a is formed along the The SRO film 14a is aligned so that the <100> direction of the upper surface 11a of the substrate 11 made of the silicon substrate is parallel to the <100> direction of the upper surface 11a of the substrate 11 itself.

In addition, as shown in Table 1, the lattice constant of SRO is 0.390 to 0.393 nm, the lattice constant of PZT is 0.411 nm, and the unconformity of the lattice constant of PZT with respect to the lattice constant of SRO is 4.5 to 5.2% relative to Since it is smaller, the integration of the lattice constant of PZT with respect to the lattice constant of SRO is good. Therefore, as shown in FIG. 7, the piezoelectric film 15 containing PZT can be epitaxially grown on the (100) plane of the film 14 containing SRO. That is, the piezoelectric film 15 containing PZT can be tetragonal to exhibit (001) orientation or the quasi-cubic crystal structure on the (100) surface of the film 14 containing SRO to exhibit (100) orientation, The crystallinity of the piezoelectric film 15 is improved.

The piezoelectric film 15 has a tetragonal crystal structure and includes a (001)-oriented lead titanate zirconate film 15a. In such a case, the lead titanate zirconate film 15a is along the <100> direction of the upper surface 11a of the substrate 11 which is composed of the silicon substrate of the lead titanic zirconate film 15a and the <100> direction of the upper surface 11a of the substrate 11 itself. Align in parallel.

In this way, the inventors of the present application first discovered that the piezoelectric film 15 containing lead titanate zirconate can be epitaxially grown on a silicon substrate without being rotated by 45° in a plane. This is a completely different relationship from, for example, the relationship of in-plane alignment described in the aforementioned Patent Document 2 and the aforementioned Non-Patent Document 1.

In addition, a film containing lead titanate zirconate may be formed between the film 14 and the piezoelectric film 15 . The film may be represented by the following general formula (Chemical formula 8), and may include a composite oxide represented by a quasi-cubic crystal with a (100) orientation.

Pb(Zr _1-v Ti _v )O ₃ ‧‧‧(Chemical formula 8)

Here, v satisfies 0≦v≦0.1.

In this way, the piezoelectric film 15 containing PZT can more easily exhibit a (001) orientation or a quasi-cubic crystal structure in the (100) surface of the film 14 containing SRO on the (100) surface of the film 14 containing SRO. Alignment, the crystallinity of the piezoelectric film 15 can be more easily improved.

<Film formation device>

Next, the piezoelectric film 15 included in the film structure which can improve the piezoelectric properties of the piezoelectric film and the detection sensitivity of the compression sensor using the piezoelectric film will be described. A film forming apparatus for the piezoelectric film 16 . This film forming apparatus is a sputtering apparatus for forming a film containing lead titan zirconate on the surface of a substrate by sputtering the surface of a target containing lead titan zirconate in a vacuum chamber.

In the following, a description will be given of a so-called surface applied to a film-forming apparatus for forming the piezoelectric film 16 to form a film on the lower surface of the substrate by sputtering on the upper surface of a target arranged to face the lower surface of the substrate in a vacuum chamber. An example of a face down type sputtering apparatus. However, the film forming apparatus for forming the piezoelectric film 16 is of a so-called face-up type in which a film is formed on the upper surface of the substrate by sputtering on the lower surface of a target arranged to face the upper surface of the substrate in a vacuum chamber. A sputtering apparatus is also applicable.

8 and 9 are cross-sectional views schematically showing the film forming apparatus of the embodiment. FIG. 9 is an enlarged cross-sectional view of FIG. 8 showing the vicinity of the substrate holding portion 25 and the support portion 26 . FIG. 10 is a schematic diagram showing the substrate protection provided by the film forming apparatus of the embodiment. The floor plan of the holding part.

As shown in FIG. 8 , the film forming apparatus 20 includes a vacuum chamber 21 , a vacuum evacuation unit 22 , gas supply units 23 and 24 , a substrate holding unit 25 , a support unit 26 , a rotational drive unit 27 , a substrate heating unit 28 , and an anti-adhesion unit. Plate 29 , target holding portion 31 , and power supply portion 32 . The substrate holding portion 25 holds the substrate SB. As the substrate SB, for example, a film structure in which the alignment film 12 , the conductive film 13 , and the film 14 are formed on the aforementioned substrate 11 can be used.

The vacuum chamber 21 is provided to be evacuated. The vacuum evacuation unit 22 evacuates the vacuum chamber 21 . The gas supply unit 23 supplies a rare gas such as argon (Ar) gas into the vacuum chamber 21 . The gas supply unit 24 supplies, for example, a raw material gas such as oxygen (O ₂ ) gas or nitrogen (N ₂ ) gas into the vacuum chamber 21 .

The vacuum chamber 21 includes, for example, a bottom plate portion 21a, a side plate portion 21b, and a top plate portion 21c. An opening OP1 is formed in the side plate portion 21b, and a vacuum evacuation portion 22 for evacuating the vacuum chamber 21 is connected to the opening OP1. As the vacuum evacuation unit 22, for example, a cryo pump can be used.

In the example shown in FIG. 8, the opening OP2 is provided in the top plate part 21c, and the vacuum chamber 21 contains the cover part 21d which plugs the opening OP2 airtightly. The lid portion 21d includes, for example, a side plate portion 21e and a top plate portion 21f. The space formed in the vacuum chamber 21 communicates with the space surrounded by the side plate portion 21e and the top plate portion 21f. The top plate portion 21f is provided with an opening OP3. In addition, although illustration is abbreviate|omitted, in the side plate part 21b, the carrying-in port for carrying in the board|substrate SB into the vacuum chamber 21 is formed.

The gas supply part 23 is connected to the gas supply pipe 23b via the flow controller 23a, and the rare gas supplied from the gas supply part 23 is supplied into the vacuum chamber 21 from the gas supply pipe 23b by adjusting the flow rate by the flow controller 23a. In addition, the gas supply part 24 is connected to the gas supply pipe 24b via the flow controller 24a, and the raw material gas supplied from the gas supply part 24 is supplied into the vacuum chamber 21 from the gas supply pipe 24b by adjusting the flow rate by the flow controller 24a. . In addition, in the example shown in FIG. 8, the case where the gas supply pipe 23b and the gas supply pipe 24b are the same is shown, but the gas supply pipe 23b and the gas supply pipe 24b may be provided separately.

The substrate holding unit 25 holds the substrate SB in the vacuum chamber 21 . As shown in FIGS. 8 to 10 , the substrate holding portion 25 is in contact with the substrate holding portion 25 at the outer peripheral portion of the substrate SB, and holds the substrate SB in a state where the central portion of the substrate SB is spaced from the substrate holding portion 25 .

Consider, for example, a case where the substrate holding portion 25 overlaps the entire surface of the lower surface of the substrate SB in a plan view, and the substrate holding portion 25 is in contact with the entire surface of the lower surface of the substrate SB, for example. In such a case, the central portion of the substrate SB is not easily thermally insulated from the substrate holding portion 25 , and is easily affected by heat from the substrate holding portion 25 . Moreover, since the center part of the board|substrate SB is easily influenced by the heat capacity of the board|substrate holding part 25, it is difficult to control the temperature of the center part of the board|substrate SB. Therefore, when the substrate SB is heated by the substrate heating unit 28, the actual temperature of the central portion of the substrate SB is shifted from the target temperature, etc., so that the crystallinity and other qualities of the film formed on the surface of the substrate SB vary.

On the other hand, in the present embodiment, the outer peripheral portion of the substrate SB is in contact with the substrate holding portion 25 , but the central portion of the substrate SB is separated from the substrate holding portion 25 . In such a case, the central portion of the substrate SB is likely to be thermally insulated from the substrate holding portion 25 and is not easily affected by the heat from the substrate holding portion 25 . In addition, the central portion of the substrate SB is not easily affected by the heat capacity of the substrate holding portion 25 . Therefore, it is easy to control the temperature of the central portion of the substrate SB. Therefore, when the substrate SB is heated by the substrate heating unit 28, the actual temperature of the central portion of the substrate SB can be prevented or suppressed from being shifted from the target temperature, and the crystallinity of the film formed on the surface of the substrate SB can be prevented or suppressed. Quality is discrete.

As described above, the film forming apparatus 20 of the present embodiment forms a film on the lower surface of the substrate SB by sputtering on the upper surface of the target TG arranged to face the lower surface of the substrate SB in the vacuum chamber 21 . A face down type sputtering apparatus. In such a case, since the substrate holding portion 25 does not overlap with the lower surface of the substrate SB in plan view, for example, a film can be formed on the central portion of the lower surface of the substrate SB.

The shape of the substrate holding portion 25 is not particularly limited, but the substrate holding portion 25 preferably includes an insulating surrounding portion 25a that is formed of an insulating member and surrounds the substrate SB in a plan view, and is formed of an insulating member, and A plurality of protruding portions 25b respectively protruding from the insulating surrounding portion 25a toward the center side of the substrate SB in a plan view are preferable. That is, it is preferable that the board|substrate holding part 25 has a so-called five virtue shape (refer FIG.10(A)). Further, the substrate holding portion 25 preferably holds the substrate SB in a state where the outer peripheral portion (outer edge portion) of the lower surface of the substrate SB is in contact with the upper surface of each of the plurality of protruding portions 25b. The plurality of protruding portions 25b are arranged so as to be relatively inwardly arranged in a polygonal shape formed by the plurality of protruding portions 25b connected in sequence in a plan view of the center of gravity of the substrate SB held by the plurality of protruding portions 25b. good.

The smaller the contact area of one protruding portion 25b with the substrate SB, the more thermal and electrical effects on the substrate SB during film formation can be reduced, and the contact area is preferably 20 mm ² or less. In short, by reducing the contact area between the substrate SB and the protruding portion 25b as much as possible, both thermal insulation and electrical insulation can be achieved, and the substrate can be charged by the electrons of the plasma without escaping the heat accumulated in the substrate.

The protruding portion 25b has the shape shown in FIGS. 10(B) to (D). Fig. 10(B) is a front view of the protruding portion 25b, Fig. 10(C) is a top view of the protruding portion 25b, and Fig. 10(D) is a side view of the protruding side 25b. The corner 25b1 of the protrusion 25b is not sharp but has a curved surface. If the corner is sharp, the film formed on the corner tends to peel off, and if the corner has a curved surface, the film formed on the corner becomes less likely to peel off, and particles can be reduced.

In addition, the protruding portion 25b may be referred to as an insulating substrate holding portion, and the insulating surrounding portion 25a and the protruding portion 25b may be collectively referred to as an insulating substrate holding portion. The insulating surrounding portion 25a may also be referred to as a third insulating member.

In such a case, no part of the substrate holding portion 25 is disposed under the central portion of the substrate SB. Therefore, the central portion of the substrate SB is more likely to be thermally insulated from the substrate holding portion 25, and is less likely to receive heat from the substrate holding portion. 25 thermal effects. Moreover, since the center part of the board|substrate SB is less easily influenced by the heat capacity of the board|substrate holding part 25, it becomes easier to control the temperature of the center part of the board|substrate SB. Therefore, when the substrate SB is heated by the substrate heating unit 28, the actual temperature of the central portion of the substrate SB can be prevented or suppressed from being shifted from the target temperature, and the film formed on the surface of the substrate SB can be further prevented or suppressed. The crystallinity and other qualities are discrete.

The insulating member of the insulating surrounding portion 25a and each insulating member of the plurality of protruding portions 25b are not particularly limited, but for example, the use of Quartz such as fused silica or synthetic quartz, or alumina is preferable. Of these, when the substrate SB is formed of a silicon substrate, it is more preferable that the insulating members of the plurality of protrusions 25b be formed of quartz from the viewpoint of contacting the substrate SB and preventing contamination of the substrate SB.

Moreover, the board|substrate holding part 25 may be comprised further by the electroconductive member, and may include the electroconductive enclosure part 25c surrounding the insulating enclosure part 25a. The stepped portion 25d may be formed on the inner edge portion of the conductive surrounding portion 25c, and the substrate holding portion 25 may be formed by the outer edge portion of the insulating surrounding portion 25a being held by the stepped portion 25d.

As the substrate SB held by the substrate holding portion 25, a substrate SB composed of a wafer having a circular shape in plan view can be used. At this time, the substrate holding portion 25 rotatably holds the substrate SB in a state where the rotation axis RA1 passes through the center CN1 (see FIG. 10 ) of the surface of the substrate SB.

In addition, the direction in which the rotation axis RA1 extends may be a direction parallel to the vertical direction. At this time, the surface of the substrate SB held by the substrate holding portion 25 is parallel to the horizontal plane.

The support portion 26 is attached to the vacuum chamber 21 and supports the substrate holding portion 25 in the vacuum chamber 21 . The support portion 26 includes conductive members (conductive members 41 and 42 described later) that are attached to the vacuum chamber 21 and support the substrate holding portion 25 in the vacuum chamber 21 . The support portion 26 is provided so as to be integrally rotatable with the substrate holding portion 25 centered on the rotation axis RA1 perpendicular to the surface of the substrate SB. The rotary drive part 27 rotates and drives the support part 26 .

In the example shown in FIGS. 8 and 9 , the support portion 26 includes, as the conductive member, the conductive member 41 attached to the vacuum chamber 21 , and the conductive member 41 attached to the conductive member 21 . The conductive member 42 of the conductive member 41 . The conductive members 41 and 42 are provided so as to be integrally rotatable with the substrate holding portion 25 around the rotation axis RA1. The rotational drive unit 27 rotationally drives the conductive members 41 and 42 .

In addition, the conductive member 42 may also be referred to as a conductive support portion, and the conductive member 42 and the conductive surrounding portion 25c may be collectively referred to as a conductive support portion. In addition, the electroconductive surrounding member 25c may also be called a 1st electroconductive member. In addition, the conductive member 42 may also be referred to as a second conductive member.

The conductive member 41 includes a base portion 41a having a cylindrical shape, and a shaft portion 41b having a cylindrical shape that is integrally rotatable with the base portion 41a and having a diameter smaller than that of the base portion 41a. Further, the conductive member 41 has an annular shape and includes a continuous portion 41c that connects the base portion 41a and the shaft portion 41b. The base portion 41a, the shaft portion 41b, and the connecting portion 41c are integrally formed, and the base portion 41a, the shaft portion 41b, and the connecting portion 41c are made of metal such as stainless steel, for example.

The conductive member 41 is provided such that the shaft portion 41b protrudes upward from the opening OP3 of the cover portion 21d, and the shaft portion 41b protruding upward from the opening OP3, for example, the sealing portion CE1 formed of a magnetic fluid seal, is airtight. ground is installed in the opening OP3. In addition, the shaft portion 41b is provided so as to be rotatable around a rotation axis RA1 perpendicular to the surface of the substrate SB via the seal portion CE1. Therefore, the shaft portion 41b is attached to the vacuum chamber 21 that is the lid portion 21d. At this time, the shaft portion 41b is electrically connected to the vacuum chamber 21 . As described above, the vacuum chamber 21 is made of metal such as stainless steel, for example, and is grounded. Therefore, the conductive member 41 is also grounded.

The rotary drive unit 27 includes, for example, a motor 27a, a belt 27b, and a pulley 27c. The shaft portion 41b is connected to the motor 27a through the pulley 27c and the belt 27b of the rotating shaft 27d. The rotational driving force of the motor 27a is transmitted to the shaft portion 41b through the belt 27b and the pulley 27c, and the rotational driving portion 27 rotationally drives the conductive member 41 around the rotational axis RA1.

The conductive member 42 includes a base portion 42a having a cylindrical shape, and a shaft portion 42b having a cylindrical shape that is integrally rotatable with the base portion 42a and has a diameter smaller than that of the base portion 42a. Further, the conductive member 42 has an annular shape and includes a continuous portion 42c that connects the base portion 42a and the shaft portion 42b. The base portion 42a, the shaft portion 42b, and the connecting portion 42c are integrally formed, and the base portion 42a, the shaft portion 42b, and the connecting portion 42c are made of metal such as stainless steel, for example.

The base portion 42a is concentric with the base portion 41a so that the outer peripheral surface of the base portion 42a faces the inner peripheral surface of the base portion 41a. The shaft portion 42b is concentric with the shaft portion 41b so that the outer peripheral surface of the shaft portion 42b faces the inner peripheral surface of the shaft portion 41b. The connecting portion 42c is fixed to the connecting portion 41c via the insulating member 51, whereby the conductive member 42 is provided so as to be rotatable integrally with the conductive member 41. As shown in FIG. As the insulating member 51, for example, an insulating member made of alumina can be used.

The base portion 42a is fixed to the board holding portion 25 using, for example, a screw 43 made of a conductive structure. Therefore, when the substrate holding portion 25 has the conductive surrounding portion 25c, that is, when it has conductivity, the potential of the conductive surrounding portion 25c, that is, the substrate holding portion 25 is equal to the potential of the base portion 42a, that is, the conductive member 42. Alternatively, when the substrate holding portion 25 does not have the conductive surrounding portion 25c, that is, when the substrate holding portion 25 does not have conductivity, the potential of the portion of the substrate holding portion 25 in contact with the screw 43 is equal to the base portion 42a, that is, the electrical potential of the conductive member 42. potential.

In addition, as described above, the conductive member 42 is fixed to the substrate holding portion 25 by using, for example, the screw 43 made of the conductive member, and is attached to the conductive member 41 of the vacuum chamber 21 to serve as the intervening insulating member 51 , the conductive member 42 and the screw 43 support the board holding portion 25 . At this time, the insulating member 51 is interposed between the conductive member 41 and the substrate holding portion 25 .

In addition, the conductive member 42 serves to support the board holding portion 25 through the screw 43 . At this time, the insulating member 53 is interposed between the vacuum chamber 21 and the conductive member 42 , and the conductive member 42 is in an electrically floating state with respect to the vacuum chamber 21 .

Moreover, the insulating member 52 is provided around the screw 43 which consists of an electroconductive member. As the insulating member 52, for example, an insulating member made of alumina can be used. At this time, since the insulating member 52 is disposed between the conductive member 41 and the substrate holding portion 25 , it can be said that the insulating member 52 is interposed between the conductive member 41 and the substrate holding portion 25 .

Consider the case where the insulating member 51 is not interposed between the conductive member 41 and the substrate holding portion 25 , and the conductive member 41 and the substrate holding portion 25 are in electrical contact. In such a case, when the substrate holding portion 25 has the conductive surrounding portion 25c, that is, when it has conductivity, the conductive surrounding portion 25c, that is, the substrate holding portion 25 is grounded, and the conductive surrounding portion 25c is also That is, the potential of the substrate holding portion 25 becomes zero potential. Therefore, when the target TG is sputtered by generating plasma in the vacuum chamber 21, the plasma or electrons are easily affected by the ground potential (zero potential), and it is difficult to stably seal between the target TG and the substrate SB. That is, when a piezoelectric film such as lead zirconate titanate is formed, the electric charge distribution of the piezoelectric film during film formation is difficult to be constant, and the quality of the film such as crystallinity is difficult to improve.

In addition, when the substrate holding portion 25 does not have the conductive surrounding portion 25c, that is, when the substrate holding portion 25 does not have conductivity, the plasma and electrons are still easily affected by the ground potential (zero potential), and it is still difficult to stably encapsulate the target. between TG and substrate SB.

On the other hand, in the present embodiment, the insulating member 52 is interposed between the conductive member 41 and the substrate holding portion 25 . In such a case, when the substrate holding portion 25 has the conductive surrounding portion 25c, that is, when the substrate holding portion 25 has conductivity, the conductive surrounding portion 25c, that is, the substrate holding portion 25 is in an electrically floating state. Therefore, when the target TG is sputtered by generating plasma in the vacuum chamber 21, the plasma and electrons are not easily affected by the ground potential (zero potential), and are easily enclosed between the target TG and the substrate SB in a stable manner. That is, when a piezoelectric film such as lead zirconate titanate is formed, the electric charge distribution of the piezoelectric film during film formation is likely to be constant, and the quality of the film such as crystallinity is likely to be improved.

In addition, the insulating member 53 may be called a first insulating member, the insulating member 52 may be called a first insulating member, and the insulating member 53 and the insulating member 52 may be collectively called a first insulating member.

Further, even when the substrate holding portion 25 does not have the conductive surrounding portion 25c, that is, when the substrate holding portion 25 does not have conductivity, compared with the case where the insulating member 52 is not interposed between the conductive member 41 and the substrate holding portion 25, Plasma and electrons are not easily affected by the ground potential (zero potential), and are easily enclosed between the target TG and the substrate SB in a stable manner.

In addition, when a certain member has conductivity, it means that the resistivity of the member is, for example, 10 ^-6 Ωm or less. On the other hand, when a certain member has insulating properties, it means that the resistivity of the member is, for example, 10 ⁸ Ωm or more.

As described above, the insulating members 52 and 53 are interposed between the vacuum chamber 21 and the conductive member 42, and the conductive member 42 is in an electrically floating state.

Considering that the insulating member 53 is not interposed between the vacuum chamber 21 and the conductive member 42, the vacuum chamber 21 and the conductive member 42 are in electrical contact with each other. In such a case, when the substrate holding portion 25 has the conductive surrounding portion 25c, that is, when it has conductivity, the conductive surrounding portion 25c, that is, the substrate holding portion 25 is grounded, and the conductive surrounding portion 25c is also That is, the potential of the substrate holding portion 25 becomes zero potential. Therefore, when the target is sputtered by generating plasma in the vacuum chamber 21, the plasma or electrons are easily affected by the ground potential (zero potential), and it is difficult to stably seal between the target TG and the substrate SB.

In addition, when the substrate holding portion 25 does not have the conductive surrounding portion 25c, that is, when the substrate holding portion 25 does not have conductivity, the plasma and electrons are still easily affected by the zero potential, and it is still not easy to stably encapsulate the target TG and the substrate SB. between.

On the other hand, in the present embodiment, the insulating member 53 is interposed between the vacuum chamber 21 and the conductive member 42, and the conductive member 42 is in an electrically floating state. In such a case, when the substrate holding portion 25 has the conductive surrounding portion 25c, that is, when the substrate holding portion 25 has conductivity, the conductive surrounding portion 25c, that is, the substrate holding portion 25 is in an electrically floating state. Therefore, when the target TG is sputtered by generating plasma in the vacuum chamber 21, the plasma and electrons are not easily affected by the ground potential (zero potential), and are easily enclosed between the target TG and the substrate SB in a stable manner. That is, in the case of forming a piezoelectric film such as lead titanate zirconate, the electric charge distribution of the piezoelectric film during film formation tends to be constant, resulting in The quality of the film such as crystallinity is easily improved.

In addition, even when the substrate holding portion 25 does not have the conductive surrounding portion 25c, that is, when the substrate holding portion 25 does not have conductivity, compared with the case where the insulating member 53 is not interposed between the vacuum chamber 21 and the conductive member 42, plasma Or electrons are not easily affected by the ground potential (zero potential), and are easily enclosed between the target TG and the substrate SB in a stable manner.

In addition, the insulating member 53 may be disposed, for example, between the upper end portion of the shaft portion 41b and the shaft portion 42b, between the lower end portion of the shaft portion 41b and the lower end portion of the shaft portion 42b, and between the lower surface and the connection portion of the connection portion 41c, respectively. between the upper surfaces of the portion 42c. As the insulating member 53, for example, an insulating member made of PEEK (Poly Ether Ether Keton) resin or alumina can be used.

In addition, the slip ring 44 which surrounds the axial part 42b of the electroconductive member 42 may be provided. The inner peripheral surface of the slip ring 44 is in contact with the outer peripheral surface of the shaft portion 42b. In such a case, the electric potential of the shaft portion 42b can be freely controlled through the slip ring 44, so that the electric potential of the conductive member 42 can be controlled so that the electric potential becomes a constant electric potential.

As shown in FIGS. 8 and 9 , the support portion 26 may include a conductive member 45 that supports the substrate holding portion 25 . The conductive member 45 includes a base portion 45a having a cylindrical shape, and a shaft portion 45b having a cylindrical shape that is integrally rotatable with the base portion 45a and has a diameter smaller than that of the base portion 45a. Further, the conductive member 45 has an annular shape and includes a continuous portion 45c that connects the base portion 45a and the shaft portion 45b. The base portion 45a, the shaft portion 45b, and the connecting portion 45c are integrally formed, and the base portion 45a, the shaft portion 45b, and the connecting portion 45c are made of stainless steel, for example. etc. metal composition.

In the example shown in FIGS. 8 and 9, the base portion 45a is concentric with the base portion 42a and the base portion 41a so that the outer peripheral surface of the base portion 45a faces the inner peripheral surface of the base portion 42a. The shaft portion 45b is concentric with the shaft portion 42b and the shaft portion 41b so that the outer peripheral surface of the shaft portion 45b faces the inner peripheral surface of the shaft portion 42b. The connecting portion 45c is fixed to the connecting portion 42c and the connecting portion 41c via the insulating member 54, whereby the conductive member 45 is rotatable integrally with the conductive member 42 and the conductive member 41.

In addition, as described above, the conductive member 42 is fixed to the board holding portion 25 by using, for example, the screw 43 made of the conductive member, and the conductive member 45 is interposed between the insulating member 51, the conductive member 42, and the screw. 43 , the substrate holding portion 25 is supported. At this time, the insulating member 52 is interposed between the conductive member 45 and the substrate holding portion 25 .

Moreover, as mentioned above, the insulating member 52 is provided around the screw 43 which consists of an electroconductive member. At this time, since the insulating member 52 is disposed between the conductive member 45 and the substrate holding portion 25 , it can be said that the insulating member 52 is interposed between the conductive member 45 and the substrate holding portion 25 .

In addition, between the upper end portion of the shaft portion 42b and the shaft portion 45b, between the lower end portion of the shaft portion 42b and the lower end portion of the shaft portion 45b, and between the lower surface of the connecting portion 42c and the upper surface of the connecting portion 45c, respectively, The insulating member 54 is interposed. As the insulating member 54, for example, an insulating member made of PEEK resin or alumina can be used.

The substrate heating unit 28 heats the substrate SB. The substrate heating portion 28 is arranged to face the upper surface of the substrate SB held by the substrate holding portion 25, and can be connected to the support portion 26 are integrally rotatably provided. As the substrate heating unit 28, a lamp unit including, for example, an infrared lamp can be used.

The anti-adhesion plate 29 is composed of a conductive member attached to the vacuum chamber 21 . The anti-adhesion plate 29 is a film-forming device 20 , which prevents the film-forming material from adhering to the inside of the vacuum chamber 21 when a film is formed by sputtering the surface of the target TG and adhering the film-forming material to the surface of the substrate SB. Parts that do not want the film-forming material to adhere. In the present embodiment, the anti-adhesion plate 29 prevents the film-forming material from adhering to the portion around the substrate SB held by the substrate holding portion 25 in plan view. In the example shown in FIG. 8 , the anti-adhesion plate 29 prevents the film-forming material from adhering to the substrate holding portion 25 . As an electroconductive member which comprises the anti-adhesion plate 29, the electroconductive member which consists of stainless steel can be used. Thereby, the temperature of the anti-adhesion plate 29 can be easily adjusted by, for example, the cooling pipe 29a through which cooling water is passed, and the influence of the anti-adhesion plate 29 on the temperature of the substrate SB held in the substrate holding portion 25 can be reduced.

In addition, the anti-adhesion plate 29 is arranged at a distance within 30 mm (preferably within 25 mm, more preferably within 20 mm) from the substrate SB.

In addition, the reason why it is preferable to water-cool the anti-adhesion plate 29 is as follows. If the anti-adhesion plate is not water-cooled, the hardness of the film attached to the anti-adhesion plate will become high and it will be easy to peel off. On the other hand, if the anti-adhesion plate 29 is water-cooled, the thermal energy when the film grows on the surface of the anti-adhesion plate 29 will decrease. , the film stress also becomes smaller, so the attached film becomes difficult to peel off. As a result, the maintenance period of the film forming apparatus can be prolonged.

In addition, the anti-adhesion plate 29 may also be referred to as a conductive anti-adhesion plate.

In addition, insulating properties are interposed between the vacuum chamber 21 and the anti-adhesion plate 29 The member 55 and the anti-adhesion plate 29 are in an electrically floating state. Furthermore, between the vacuum chamber 21 and the insulating member 55, the conductive member 46 is interposed, and between the insulating member 55 and the anti-adhesion plate 29, the conductive member 47 is interposed, and the conductive member 46 and the conductive member 47 are interposed. In the state where the insulating member 55 is interposed, the screw 56 composed of the insulating member may be used for the connection.

Consider the case where the vacuum chamber 21 and the anti-adhesion plate 29 are in electrical contact without interposing the insulating member 55 between the vacuum chamber 21 and the anti-adhesion plate 29 . In such a case, the anti-adhesion plate 29 is in a grounded state, and the potential of the anti-adhesion plate 29 becomes zero potential. Therefore, when the target TG is sputtered by generating plasma in the vacuum chamber 21, the plasma or electrons are easily affected by the ground potential (zero potential), and it is difficult to stably seal between the target TG and the substrate SB. That is, when a piezoelectric film such as lead zirconate titanate is formed, the electric charge distribution of the piezoelectric film during film formation is difficult to be constant, and the quality of the film such as crystallinity is difficult to improve.

In addition, if the anti-adhesion plate 29 arranged within a distance of 30 mm from the substrate SB is brought to the ground potential and the piezoelectric film is formed on the substrate SB, the piezoelectric film located at the end of the substrate SB becomes cloudy. If the anti-adhesion plate 29 is set farther than 30 mm, the piezoelectric film will not become cloudy even if the anti-adhesion plate is at the ground potential, but the anti-adhesion plate at such a distance cannot fully function as an anti-adhesion plate.

In addition, the insulating member 55 may also be referred to as a second insulating member.

On the other hand, in the present embodiment, the insulating member 55 is interposed between the vacuum chamber 21 and the anti-adhesion plate 29 . In such a case, the anti-adhesion plate 29 is in an electrically floating state. Therefore, when the target TG is sputtered by generating plasma in the vacuum chamber 21, the plasma or electrons are not easily subjected to the ground potential (zero electric potential). position), it is easy to stably encapsulate between the target TG and the substrate SB. That is, when a piezoelectric film such as lead zirconate titanate is formed, the electric charge distribution of the piezoelectric film during film formation is likely to be constant, and the quality of the film such as crystallinity is likely to be improved.

In this way, in the film forming apparatus 20 of the present embodiment, the conductive arrangement is not arranged near the substrate SB (specifically, the distance from the substrate SB is 30 mm or less, preferably 25 mm or less, more preferably 20 mm or less). Even if the conductive member is placed in the vicinity of the substrate SB, the conductive member can be electrically floated, and plasma or electrons can be stably enclosed between the target TG and the substrate SB. As a result, the inventors of the present application discovered for the first time that when a piezoelectric film such as lead zirconate titanate is formed, the electric charge distribution of the piezoelectric film during film formation tends to be constant, and the quality of the film such as crystallinity is improved. The piezoelectric film is excellent in ferroelectricity and piezoelectricity. Thereby, in the film forming apparatus for forming a piezoelectric film containing lead titanate zirconate, a piezoelectric film having good quality such as crystallinity can be formed.

Furthermore, according to the present embodiment, the substrate holding portion 25 is supported by the support portion 26 that is electrically floating with respect to the vacuum chamber 21 , so that the substrate SB held by the substrate holding portion 25 can be electrically floated with respect to the support portion 26 . . By such double floating, the electric charges accumulated on the substrate SB during film formation can be prevented from escaping to the ground potential. Thereby, a large amount of electric charges can be accumulated on the substrate, and as a result, a film with good crystallinity can be formed.

In other words, by floating the substrate SB by the support portion 26, electron leakage from the substrate due to electrons of the plasma can be prevented. When a large amount of electric charge is accumulated in the substrate, the plasma can cause the electric charge from the substrate to escape to the ground potential, or It has the property of causing abnormal discharge, so by suppressing it as much as possible, a film with good crystallinity can be formed.

In addition, by keeping the conductive member connected to the ground potential away from the substrate SB, cloudiness of the piezoelectric film formed on the substrate can be eliminated.

The target holding unit 31 holds the target TG in the vacuum chamber 21 . In addition, the target TG includes a backing plate BP1 and a target material TM1 fixed to one side of the backing plate BP1. The surface of the target TG held by the target holding portion 31 faces the surface of the substrate SB. In the example shown in FIG. 8 , the target holding portion 31 is provided below the substrate holding portion 25 on the upper surface of the target TG held by the target holding portion 31 and below the substrate SB held by the substrate holding portion 25 . face to face.

The power supply unit 32 supplies high-frequency power to the target TG. The target TG is sputtered by supplying high-frequency power to the target TG through the power supply unit 32 . That is, the film forming apparatus 20 of this embodiment is an RF (Radio Frequency, radio frequency) sputtering apparatus.

The power supply unit 32 includes a high-frequency power supply 32a and an integrator 32b. Suitably, the high-frequency power supply 32a is a high-frequency power supply with a pulse modulation function that modulates the high-frequency power into a pulse shape. The high-frequency power supply 32a is connected to the integrator 32b, and the integrator 32b is connected to the backplane BP1 of the target TG. In this embodiment, the power supply unit 32 supplies the high-frequency power to the target TG through the target holding unit 31, but the power supply unit 32 may directly supply the high-frequency power to the target TG.

In addition, the film forming apparatus may include a V _DC control unit 33 that controls the voltage V _DC of the DC component generated at the target TG to be -200V or more and -80V or less when the high-frequency power is supplied by the power supply unit 32 . The V _DC control unit 33 has a V _DC sensor and is electrically connected to the power supply unit 32 .

A suitable one is the film forming apparatus 20 having the magnet portion 34 and the magnet rotation driving portion 35 . The magnet portion 34 is provided so as to be rotatable about the rotation axis RA1, for example. The magnet rotation driving part 35 drives the magnet part 34 to rotate about the rotation axis RA1, and applies a magnetic field to the target TG through the rotationally driven magnet part 34. That is, the film-forming apparatus of this embodiment is an RF magnetron sputtering apparatus. In addition, the magnet part 34 or the magnet rotation drive part 35 is a magnetic field application part which applies a magnetic field to the target TG.

Suitably, the horizontal magnetic field of the surface of the target TG to which the magnetic field is applied (the upper surface in the example shown in FIG. 8 ) is 140 to 220 G. This is because if the horizontal magnetic field on the surface of the target TG is larger than 220G, the energy on the surface of the target TG becomes too high, and the entire film on the substrate becomes cloudy. If it is smaller than 140G, the surface energy of the target TG becomes too small. The reason is that the film formation rate is lowered and it is not practical, and the crystallinity is also lowered. When the horizontal magnetic field on the surface of the target TG is 140 G or more, plasma or electrons are more stably enclosed in the vicinity of the surface of the target TG than when the magnetic flux density on the surface of the target TG is less than 140 G. On the other hand, when the horizontal magnetic field on the surface of the target TG is 220 G or less, compared with the case where the horizontal magnetic field on the surface of the target TG exceeds 220 G, the plasma or electrons are not concentrated too much on the surface of the target TG, and the Density is enclosed. In addition, the magnetic field on the surface of the target TG is preferably along the surface of the target TG.

<Manufacturing method of membrane structure>

Next, the manufacturing method of the membrane structure of this embodiment is demonstrated. Figure 11 14 is a cross-sectional view in the manufacturing process of the membrane structure of the embodiment.

First, as shown in FIG. 11, the substrate 11 is prepared (step S1). In step S1, for example, a substrate 11 of a silicon substrate made of silicon (Si) single crystal is prepared. The substrate 11 made of a silicon single crystal has a cubic crystal structure, and has an upper surface 11a as a main surface consisting of a (100) plane. When the substrate 11 is a silicon substrate, an oxide film such as a SiO ₂ film may be formed on the upper surface 11 a of the substrate 11 .

In addition, as the substrate 11, various substrates other than silicon substrates can be used, for example, SOI (Silicon on Insulator) substrates, substrates composed of various semiconductor single crystals other than silicon, substrates composed of various oxide single crystals such as sapphire, or surface A substrate or the like made of a glass substrate on which a polysilicon film is formed.

As shown in FIG. 11 , two directions orthogonal to each other in the upper surface 11a composed of the (100) plane of the substrate 11 made of silicon single crystal are referred to as the X-axis direction and the Y-axis direction, and the direction perpendicular to the upper surface 11a is referred to as the Z-axis direction .

Next, as shown in FIG. 12, an alignment film 12 is formed on the substrate 11 (step S2). Hereinafter, in step S2, the case where the alignment film 12 is formed by the electron beam vapor deposition method will be described as an example, but it may be formed by various methods such as sputtering.

In step S2, first, the substrate 11 is heated to, for example, 700° C. in a state where the substrate 11 is placed in a certain vacuum atmosphere.

In step S2, next, Zr is evaporated by the electron beam evaporation method using the evaporation material of zirconium (Zr) single crystal. At this time, the evaporated Zr reacts with oxygen on the substrate 11 heated to 700° C., for example, to form a zirconium oxide (ZrO ₂ ) film. Next, an alignment film 12 composed of a ZrO ₂ film as a single-layer film is formed.

The alignment film 12 is epitaxially grown on the upper surface 11a of the substrate 11 made of silicon single crystal, which is the main surface, which is constituted by the (100) plane. The alignment film 12 has a cubic crystal structure and includes (100) oriented zirconia (ZrO ₂ ). That is, an alignment film 12 composed of a single-layer film containing (100)-aligned zirconia (ZrO ₂ ) is formed on the upper surface 11 a composed of the (100) plane of the substrate 11 composed of silicon single crystal.

As described using the aforementioned FIG. 11 , two directions orthogonal to each other in the upper surface 11a formed of the (100) plane of the substrate 11 made of silicon single crystal are taken as the X-axis direction and the Y-axis direction, and the direction perpendicular to the upper surface 11a as the Z-axis direction. At this time, epitaxial growth of a certain film means that the film is aligned in any one of the X-axis direction, the Y-axis direction, and the Z-axis direction.

The alignment film 12 has a cubic crystal structure and includes a (100) alignment zirconia film 12a (see FIG. 7 ). In such a case, the zirconium oxide film 12a is in the <100> direction along the upper surface 11a of the main surface of the substrate 11 composed of the silicon substrate of the zirconia film 12a and the <100> direction of the upper surface 11a of the substrate 11 itself. Align in parallel.

The thickness of the alignment film 12 is preferably 2-100 nm, more preferably 10-50 nm. By having such a film thickness, epitaxial growth can be performed to form the alignment film 12 very close to a single crystal.

Next, as shown in FIG. 4, the conductive film 13 is formed (step S3).

In this step S3, first, the conductive film 13 as a part of the lower electrode, which is epitaxially grown on the alignment film 12, is formed. The conductive film 13 is made of metal to make. As the conductive film 13 made of metal, for example, a conductive film containing platinum (Pt) is used.

When a conductive film containing Pt is formed as the conductive film 13, the conductive film 13 is epitaxially grown on the alignment film 12 at a temperature of 450 to 600°C by sputtering to form a part of the lower electrode. The conductive film 13 containing Pt is epitaxially grown on the alignment film 12 . In addition, Pt included in the conductive film 13 has a cubic crystal structure and has a (100) orientation.

The conductive film 13 has a cubic crystal structure and includes a (100)-aligned platinum film 13a (see FIG. 7 ). In such a case, the platinum film 13a is aligned so as to be parallel to the <100> direction of the upper surface 11a of the upper surface 11a of the substrate 11 composed of the silicon substrate of the platinum film 13a and the <100> direction of the upper surface 11a of the substrate 11 itself. .

In addition, instead of using a conductive film containing platinum (Pt), for example, a conductive film containing iridium (Ir) may be used instead as the conductive film 13 made of metal.

In this step S3, the conductive film 13 is then subjected to heat treatment at a temperature of 450-600°C. Specifically, after forming the conductive film 13 by sputtering at a temperature of 450 to 600° C., it is preferable to heat treatment at a temperature of 450 to 600° C. for 10 to 30 minutes.

When the temperature for heat-treating the conductive film 13 is less than 450° C., the temperature is too low to improve the crystallinity of platinum contained in the conductive film 13 and the piezoelectric film 15 formed on the conductive film 13 with the film 14 interposed therebetween. crystallinity. When the temperature for heat-treating the conductive film 13 exceeds 600° C., the temperature is too high, and the crystal grains of platinum contained in the conductive film 13 grow, so that the crystallinity of platinum cannot be improved, and the formation of the intermediary film 14 on the conductive film 13 cannot be improved. Piezoelectric film 15 crystallinity. On the other hand, when the conductive film 13 is heat-treated at a temperature of 450 to 600° C., the crystallinity of platinum contained in the conductive film 13 can be improved, and the piezoelectric film 15 formed on the conductive film 13 with the film 14 interposed therebetween can be improved. crystallinity.

In addition, when the conductive film 13 is heat-treated at a temperature of 450 to 600° C., it is preferable to keep the heat treatment for 10 to 30 minutes. If the time for heat treatment of the conductive film 13 is less than 10 minutes, the time is too short to improve the crystallinity of platinum contained in the conductive film 13 and the crystallinity of the piezoelectric film 15 formed on the conductive film 13 with the film 14 interposed therebetween. . When the temperature for heat-treating the conductive film 13 exceeds 30 minutes, the time is too long, the crystal grains of platinum contained in the conductive film 13 grow, and the crystallinity of platinum cannot be improved, and the formation of the intermediary film 14 on the conductive film 13 cannot be improved. Crystallinity of the piezoelectric film 15 .

Next, as shown in FIG. 13, the film 14 is formed (step S4). In this step S4, the film 14 containing the complex oxide represented by the aforementioned general formula (chemical formula 4) is formed on the conductive film 13. As the composite oxide represented by the aforementioned general formula (Chemical formula 4), for example, a conductive film containing strontium titanate (STO), strontium titanate ruthenate (STRO), or strontium ruthenium (SRO) can be formed. When the SRO-containing conductive film is formed as the composite oxide represented by the general formula (Chemical formula 4), in step S4, the conductive film 14 as a part of the lower electrode is formed on the conductive film 13 . Moreover, in the said general formula (Chemical formula 4), z satisfies 0≦z≦1.

When a conductive film containing STO, STRO, or SRO is formed as the film 14, an epitaxially grown film 14 is formed on the conductive film 13 at a temperature of about 600° C. by sputtering as a part of the lower electrode . The film 14 containing STO, STRO or SRO is epitaxially grown on the conductive film 13 . this In addition, the STO, STRO or SRO contained in the film 14 is represented by a quasi-cubic crystal or a cubic crystal represented by a (100) orientation.

The film 14 has a quasi-cubic crystal structure and includes the SRO film 14a (refer to FIG. 7 ) having a (100) orientation. In such a case, the SRO film 14a is aligned so as to be parallel to the <100> direction of the upper surface 11a of the upper surface 11a of the substrate 11 composed of the silicon substrate of the SRO film 14a so as to be parallel to the <100> direction of the upper surface 11a of the substrate 11 itself .

In addition, instead of the sputtering method, the film 14 can be formed by a coating method such as a sol-gel method, for example. In such a case, in step S4, first, on the film 14, a solution containing strontium and ruthenium, strontium, titanium and ruthenium, or strontium and titanium is applied to form a composite oxide containing the general formula (Chemical formula 4) described above. membrane of the precursor. In addition, when the film 14 is formed by the coating method, in step S4, the precursor is then oxidized and crystallized by heat-treating the film to form the film 14 including the complex oxide represented by the general formula (Chemical formula 4) described above. .

Next, as shown in FIG. 14, the piezoelectric film 16 is formed (step S5). In this step S5, a piezoelectric film 16 including a composite oxide composed of lead zirconate titanate (PZT) represented by the aforementioned general formula (Chemical formula 6) is formed on the film 14 by, for example, sputtering. Here, in the aforementioned general formula (Chemical formula 6), x satisfies 0.32≦x≦0.52.

Among them, when x satisfies 0.32≦x≦0.48, the PZT included in the piezoelectric film 16 has a crystal structure of rhombohedral crystals that should be originally composed of tetragonal crystals mainly due to the binding force from the substrate 11 or the like. structure, and easy to (001) alignment. Next, the piezoelectric film 16 containing PZT is epitaxial grown on the membrane 14 . In addition, when x satisfies 0.48<x≦0.52, the PZT included in the piezoelectric film 16 has a tetragonal crystal structure because of its composition, and has a tetragonal crystal structure and has a (001) orientation. Next, the piezoelectric film 16 containing PZT is epitaxially grown on the film 14 . Thereby, the direction of the polar axis of the lead zirconate titanate contained in the piezoelectric film 16 can be aligned approximately perpendicular to the upper surface 11a, so that the piezoelectric properties of the piezoelectric film 16 can be improved.

The piezoelectric film 16 has a tetragonal crystal structure and includes a (001)-oriented lead titanate zirconate film 16a (see FIG. 7 ). In such a case, the lead titanate zirconate film 16a is along the <100> direction of the upper surface 11a of the substrate 11 made of the silicon substrate of the lead titanic zirconate film 16a, and the <100> direction of the upper surface 11a of the substrate 11 itself Align in parallel.

For example, when the piezoelectric film 16 is formed by sputtering, each of the plurality of crystal grains 16 g (see FIG. 5 ) included in the piezoelectric film 16 can be polarized by plasma. That is, each of the plurality of crystal grains 16g included in the piezoelectric film 16 to be formed has spontaneous polarization. Further, the spontaneous polarization of each of the plurality of crystal grains 16 g includes a polarization component P1 parallel to the thickness direction of the piezoelectric film 16 (see FIG. 5 ). Next, the polarization components P1 included in the spontaneous polarization included in each of the plurality of crystal grains 16g are oriented in the same direction as each other. As a result, the formed piezoelectric film 16 has spontaneous polarization as the entire piezoelectric film 16 before the polarization treatment is performed.

That is, in step S5, when the piezoelectric film 16 is formed by the sputtering method, the piezoelectric film 16 can be polarized by plasma. As a result, as described with reference to FIG. 6 , when the film structure 10 of the present embodiment is used as a piezoelectric element, it is not necessary to perform polarizing treatment on the piezoelectric film 16 before use.

In addition, in step S5, when the piezoelectric film 16 is formed by sputtering, for example, the piezoelectric film 16 expands due to the injection of sputtered particles and argon (Ar) gas in the piezoelectric film 16, and the piezoelectric film 16 Has compressive stress.

Suitably, in step S5, at a temperature of 425 to 475° C. and a film-forming speed of 0.29 nm/s or less, a film containing PZT as a composite oxide is formed, and a pressure-sensitive film composed of the film to be formed is formed. Electric film 16 . Under such conditions, it is possible to easily obtain a membrane structure that satisfies the above-mentioned formula (Formula 1) and formula (Formula 2).

Alternatively, it is appropriate to form an underlayer film containing PZT as a complex oxide at a temperature of 425 to 475° C. and a first film-forming rate of 0.29 nm/s or less in step S5 . Next, on the lower layer film, at a temperature of 425 to 475° C., and at a second film formation rate that is lower than the first film formation rate, an upper layer film containing PZT as a composite oxide is formed to form an upper layer film composed of a composite oxide. The piezoelectric film 16 constituted by the lower film and the upper film. Under such conditions, it is possible to easily obtain a membrane structure that satisfies the above-mentioned formula (Formula 1) and formula (Formula 2).

Here, a film forming method for forming the piezoelectric film 16 using the film forming apparatus 20 described above with reference to FIGS. 8 to 10 will be described.

First, the target TG is held in the vacuum chamber 21 by the target holding portion 31 .

Next, the substrate SB is held in the vacuum chamber 21 by the substrate holding portion 25 . As the substrate SB, for example, a film structure in which the alignment film 12 , the conductive film 13 , and the film 14 are formed on the aforementioned substrate 11 can be used. The substrate holding portion 25 is supported by a support portion 26 attached to the vacuum chamber 21 , and an insulation is provided between the support portion 26 and the substrate holding portion 25 or between the vacuum chamber 21 and the support portion 26 . Sexual member 51 mediates. Further, the substrate holding portion 25 is in contact with the substrate holding portion 25 at the outer peripheral portion of the substrate SB, and holds the substrate SB in a state where the central portion of the substrate SB is spaced from the substrate holding portion 25 . The support portion 26 includes conductive members 41 and 42 . The conductive members 41 and 42 are provided so as to be integrally rotatable with the substrate holding portion 25 around the rotation axis RA1. The conductive member 42 is in an electrically floating state. Thereby, plasma and electrons are not easily affected by the ground potential (zero potential), and are easily enclosed between the target TG and the substrate SB in a stable manner.

The board holding portion 25 includes an insulating surrounding portion 25a formed of an insulating member and surrounding the substrate SB in a plan view, and an insulating member formed of an insulating member and facing the center side of the substrate SB from the insulating surrounding portion 25a in a plan view A plurality of protruding portions 25b respectively protrude. The substrate holding portion 25 holds the substrate SB in a state where the outer peripheral portion (outer edge portion) of the lower surface of the substrate SB is in contact with the upper surface of each of the plurality of protruding portions 25b. Thereby, when the substrate SB is heated by the substrate heating unit 28, the actual temperature of the central portion of the substrate SB can be prevented or suppressed from being shifted from the target temperature.

Next, the substrate SB is heated by the substrate heating unit 28 , the conductive members 41 and 42 are rotationally driven by the rotary drive unit 27 , a magnetic field is applied to the target TG by the magnet unit 34 , and high voltage is supplied to the target TG by the power supply unit 32 . The piezoelectric film 16 is formed on the surface of the substrate SB by sputtering the surface of the target TG in the vacuum chamber 21 in a state of high frequency power.

In addition, the film forming apparatus 20 forms the piezoelectric film 16 on the surface of the target TG and the surface of the substrate SB by adhering the film forming material by sputtering. Anti-adhesion board composed of sexual components 29 , preventing the film-forming material from adhering to the substrate holding portion 25 . An insulating member 55 is interposed between the anti-adhesion plate 29 and the vacuum chamber 21, and the anti-adhesion plate 29 is in an electrically floating state. Thereby, plasma and electrons are not easily affected by the ground potential (zero potential), and are easily enclosed between the target TG and the substrate SB in a stable manner.

Next, as shown in FIG. 1, the piezoelectric film 17 is formed (step S6). In this step S6, the piezoelectric film 17 including the composite oxide composed of lead zirconate titanate (PZT) represented by the aforementioned general formula (chemical formula 7) is deposited on the piezoelectric film 16 by, for example, a sol-gel method or the like. formed by coating. Hereinafter, a method of forming the piezoelectric film 17 by the sol-gel method will be described.

In step S6, first, a film containing a PZT precursor is formed on the piezoelectric film 16 by applying a solution containing lead, zirconium and titanium. In addition, the step of applying the solution containing lead, zirconium, and titanium may be repeated several times, thereby forming a film including a plurality of films stacked on each other.

In step S6, next, the precursor is oxidized and crystallized by heat-treating the film to form the piezoelectric film 17 including PZT. Here, in the aforementioned general formula (chemical formula 7), y satisfies 0.32≦y≦0.48.

Among them, when y satisfies 0.32≦y≦0.48, the PZT included in the piezoelectric film 17 has a crystal structure of rhombohedral crystals that should be originally composed of tetragonal crystals mainly due to the restraint force from the substrate 11 or the like. structure, and easy to (001) alignment. Next, the piezoelectric film 17 containing PZT is epitaxially grown on the piezoelectric film 16 . In addition, when y satisfies 0.48<y≦0.52, the PZT included in the piezoelectric film 17 has a tetragonal crystal structure and has a (001) orientation because of its composition. Next, the piezoelectric film 17 containing PZT is epitaxially grown on the piezoelectric film 16 . Thereby, the direction of the polar axis of the lead zirconate titanate contained in the piezoelectric film 17 can be aligned approximately perpendicular to the upper surface 11a, so that the piezoelectric characteristics of the piezoelectric film 17 can be improved.

The piezoelectric film 17 has a tetragonal crystal structure and includes a (001)-oriented lead titanate zirconate film 17a (see FIG. 7 ). In such a case, the lead titanate zirconate film 17a is along the <100> direction of the upper surface 11a of the substrate 11 which is formed of the silicon substrate of the lead titanic zirconate film 17a, and the <100> direction of the upper surface 11a of the substrate 11 itself. Align in parallel.

When PZT having a tetragonal crystal structure is (001) oriented, the polarization direction parallel to the [001] direction and the electric field direction parallel to the thickness direction of the piezoelectric film 15 are parallel to each other, thereby improving piezoelectric properties. That is, when an electric field along the [001] direction is applied to PZT having a tetragonal crystal structure, piezoelectric constants d ₃₃ and d ₃₁ of large absolute values can be obtained. Therefore, the piezoelectric constant of the piezoelectric film 15 can be further increased. In this specification, the piezoelectric constant d ₃₁ has a negative sign originally, but the negative sign is omitted and the piezoelectric constant d 31 is represented by an absolute value.

In step S6, for example, the piezoelectric film 17 is provided with tensile stress by evaporating the solvent in the solution during heat treatment, or by film narrowing when the precursor is oxidized and crystallized.

In this way, the piezoelectric film 15 including the piezoelectric film 16 and the piezoelectric film 17 is formed, and the film structure 10 shown in FIG. 1 is formed. That is, steps S5 and S6 are included in the intervening film 14 on the conductive film 13 to form titanic acid containing tetragonal crystals expressed as (001) orientation or quasi-cubic crystals expressed as (100) alignment, and epitaxially grown The step of piezoelectric film 15 of lead.

Next, the diffraction pattern of the piezoelectric film 15 is measured by X-ray diffraction measurement using the θ-2θ method (step S7 ).

The piezoelectric film 15 has a tetragonal crystal structure and contains (001) oriented lead titanate zirconate. In this embodiment, X of the piezoelectric film 15 according to the θ-2θ method using the CuKα line. In the line diffraction pattern, when the diffraction angle of the diffraction peak of the (004) plane represented by the tetragonal crystal of lead titanate zirconate is 2θ ₀₀₄ , 2θ ₀₀₄ satisfies the following formula (Equation 1).

2θ ₀₀₄ ≦96.5°‧‧‧(Formula 1)

Thereby, the space|interval of the (004) plane represented by the tetragonal crystal of lead titanate zirconate becomes long. Alternatively, the content of lead titanate zirconate in the piezoelectric film 15 having a tetragonal crystal structure and (001) orientation may be higher than that in the piezoelectric film 15 having a tetragonal crystal structure and (100) orientation The content rate of lead titanate zirconate is even larger. That is, the polarization directions of each of the plurality of crystal grains included in the piezoelectric film 15 can be aligned, so that the piezoelectric properties of the piezoelectric film 15 can be improved.

On the other hand, when the piezoelectric film 15 includes PZT having a (100) orientation represented by a quasi-cubic crystal, in this embodiment, the X-ray diffraction of the piezoelectric film 15 by the θ-2θ method using CuKα lines In the pattern, when the diffraction angle of the diffraction peak of the (400) plane represented by the quasi-cubic crystal of lead titanate zirconate is 2θ ₄₀₀ , 2θ ₄₀₀ satisfies the aforementioned formula (Equation 1), and is replaced by 2θ ₄₀₀ instead of 2θ ₀₀₄ (2θ ₄₀₀ ≦96.5°).

In addition, in this embodiment, when the relative permittivity of the piezoelectric film 15 is ε _r , ε _r satisfies the following equation (Equation 2).

ε _r ≦450‧‧‧ (Equation 2).

Thereby, the membrane structure 10 is used, for example, as a pressure using the piezoelectric effect. When the sensor is used, the detection sensitivity can be improved, and the detection circuit of the pressure sensor can be easily designed. Alternatively, when the membrane structure 10 is used, for example, as an ultrasonic vibrator using an inverse piezoelectric effect, an oscillation circuit can be easily designed.

Further, after the piezoelectric film 17 is formed, a conductive film 18 (see FIG. 2 ) serving as an upper electrode may be formed on the piezoelectric film 17 (step S8 ). Thereby, an electric field can be applied to the piezoelectric film 17 in the thickness direction.

In addition, after forming the conductive film 18, the relative permittivity may be measured by applying an alternating voltage with a frequency of 1 kHz between the conductive film 13 and the conductive film 18 (step S9).

Suitably, when the film structure 10 has the conductive film 18, when the relative permittivity of the piezoelectric film 15 measured by applying an alternating voltage with a frequency of 1 kHz between the conductive film 13 and the conductive film 18 is _εr , the pressure ε _r of the electric film 15 satisfies the aforementioned formula (Equation 2).

By reducing the relative permittivity under an AC voltage having such a frequency, for example, the clock frequency of the detection circuit can be increased, and the response speed of the pressure sensor using the membrane structure 10 can be improved.

Suitably, when the residual extreme value of the piezoelectric film 15 is _Pr , _Pr satisfies the following formula (Equation 3).

P _r ≧28μC/cm ² ‧‧‧(Equation 3)

Thereby, since the ferroelectric property of the piezoelectric film 15 can be improved, the piezoelectric property of the piezoelectric film 15 can also be improved.

In addition, a film containing lead titanate zirconate may be formed between the film 14 and the piezoelectric film 15 . The film is represented by the aforementioned general formula (Chemical formula 8), and includes a The quasi-cubic crystal may be expressed as a composite oxide of (100) orientation.

<Variation of the implementation form>

In the embodiment, as shown in FIG. 1 , a piezoelectric film 15 including a piezoelectric film 16 and a piezoelectric film 17 is formed. However, the piezoelectric film 15 may include only the piezoelectric film 16 . Such an example will be described as a modification of the embodiment.

15 is a cross-sectional view of a membrane structure according to a modification of the embodiment.

As shown in FIG. 15 , the film structure 10 of this modification has a substrate 11 , an alignment film 12 , a conductive film 13 , a film 14 , and a piezoelectric film 15 . The alignment film 12 is formed on the substrate 11 . The conductive film 13 is formed on the alignment film 12 . The film 14 is formed on the conductive film 13 . The piezoelectric film 15 is formed on the film 14 . The piezoelectric film 15 includes the piezoelectric film 16 .

That is, the film structure 10 of the present modification is the same as the film structure 10 of the embodiment except that the piezoelectric film 15 does not include the piezoelectric film 17 (see FIG. 1 ) and only includes the piezoelectric film 16 .

When the piezoelectric film 15 includes the piezoelectric film 16 having compressive stress but does not include the piezoelectric film 17 having tensile stress (see FIG. 1 ), the piezoelectric film 15 and the piezoelectric film 16 having compressive stress and Compared with the case where the piezoelectric films 17 (see FIG. 1 ) having tensile stress are included, the amount of warpage of the film structure 10 is increased. However, for example, when the thickness of the piezoelectric film 15 is thin, the amount of warpage of the film structure 10 can be reduced. Therefore, even when the piezoelectric film 15 includes only the piezoelectric film 16, the shape accuracy of the film structure 10 can be improved, for example, when the film structure 10 is processed using a photolithographic technique, and the characteristics of the piezoelectric element formed by processing the film structure 10 can be improved. .

In addition, the membrane structure 10 of the present modification may also have the conductive film 18 (see FIG. 2 ), similarly to the membrane structure 10 of the embodiment.

[Example]

Hereinafter, the present embodiment will be further described in detail based on examples. In addition, this invention is not limited by the following Examples.

(Example 1 and Comparative Example 1)

Hereinafter, the membrane structure 10 described in the embodiment using FIG. 1 is formed as the membrane structure of Example 1. In the film structure of Example 1, the diffraction peak of the (004) plane represented by the tetragonal crystal of lead zirconate titanate is observed in the X-ray diffraction pattern of the piezoelectric film 15 by the θ-2θ method using CuKα line. When the angle is 2θ ₀₀₄ , 2θ ₀₀₄ satisfies the aforementioned formula (Equation 1). In addition, in the film structure of Example 1, when the relative permittivity of the piezoelectric film 15 is ε _r , ε _r satisfies the aforementioned formula (Equation 2). On the other hand, 2θ ₀₀₄ is the membrane structure satisfying the above-mentioned formula (Numerical formula 1), which is the membrane structure of Comparative Example 1.

Hereinafter, the formation method of the membrane structure of Example 1 is demonstrated. In addition, in the method for forming the film structure of Comparative Example 1, when the piezoelectric film 16 was formed using the RF sputtering apparatus, the high-frequency power (power) supplied was 2750 W, which was different from the high-frequency power (power) supplied. The conditions for Example 1, which is 2250W, are different.

First, as shown in FIG. 11 , as the substrate 11 , the upper surface 11 a as the main surface constituted by the (100) plane is prepared, and a wafer constituted by a 6-inch silicon single crystal is prepared.

Next, as shown in FIG. 12 , a zirconium oxide (ZrO ₂ ) film was formed on the substrate 11 as an alignment film 12 by an electron beam vapor deposition method. The conditions at this time are shown below.

Device: Electron beam evaporation device

Pressure: 7.00×10 ^-3 Pa

Evaporation source: Zr+O ₂

Accelerating voltage/radiation current: 7.5kV/1.80mA

Thickness: 24nm

Film forming speed: 0.005nm/s

Oxygen flow: 7sccm

Substrate temperature: 500℃

Next, as shown in FIG. 4, on the alignment film 12, a platinum (Pt) film was formed as a conductive film 13 by a sputtering method. The conditions at this time are shown below.

Device: DC sputtering device

Pressure: 1.20×10 ^-1 Pa

Evaporation source: Pt

Power: 100W

Thickness: 150nm

Film forming speed: 0.14nm/s

Ar flow: 16sccm

Substrate temperature: 450~600℃

Next, the Pt film is heat-treated. The conditions at this time are shown below.

Device: DC sputtering device

Substrate temperature (heat treatment temperature): 450~600℃

Heat treatment time: 10~30 minutes

Next, as shown in FIG. 13 , on the conductive film 13, an SRO film was formed as the film 14 by the sputtering method. The conditions at this time are shown below.

Device: RF magnetron sputtering device

Power: 300W

Gas: Ar

Pressure: 1.8Pa

Substrate temperature: 600℃

Film forming speed: 0.11nm/s

Thickness: 20nm

Next, as shown in FIG. 14, on the film 14, a Pb(Zr _0.58 Ti _0.42 )O ₃ film (PZT film) having a film thickness of 1 μm was formed as the piezoelectric film 16 by sputtering. The conditions at this time are shown below.

Device: RF magnetron sputtering device

Power: 2250W

Gas: Ar/O ₂

Pressure: 0.6Pa

Substrate temperature: 425℃

Film forming speed: 0.29nm/s

Ar flow: 66sccm

Oxygen flow: 6sccm

Film forming time: 4200s

Next, as shown in FIG. 1 , a Pb(Zr _0.58 Ti _0.42 )O ₃ film (PZT film) was formed on the piezoelectric film 16 as the piezoelectric film 17 by a coating method. The conditions at this time are shown below.

The organometallic compounds of Pb, Zr and Ti were mixed so as to have a composition ratio of Pb:Zr:Ti=100+δ:58:42, and a mixed solvent of ethanol and 2-n-butoxy alcohol was used as Pb( The raw material solution to be dissolved was adjusted so that the concentration of Zr _0.58 Ti _0.42 )O ₃ was 0.35 mol/l. For δ, δ=20. Next, 20 g of polyrolidone having a K value of 27 to 33 was dissolved in the raw material solution.

Next, 3 ml of the raw material solution in the prepared raw material solution was dropped onto the substrate 11 composed of a 6-inch wafer, and rotated at 3000 rpm for 10 seconds to apply the raw material solution on the substrate 11 to form a precursor containing film. Next, by placing the substrate 11 on a hot plate at a temperature of 200° C. for 30 seconds, and further placing the substrate 11 on a hot plate at a temperature of 450° C. for 30 seconds, the solvent is evaporated and the film is dried. . After that, the oxidation precursor was crystallized by heat-treating at 600 to 700° C. for 60 seconds in an oxygen (O ₂ ) atmosphere of 0.2 MPa to form a piezoelectric film 17 having a thickness of 30 nm.

For each of Example 1 and Comparative Example 1, the θ-2θ spectrum by the XRD method of the film structure until the PZT film formed as the piezoelectric film 17 was formed was measured. That is, about each of Example 1 and Comparative Example 1, X-ray diffraction measurement by the θ-2θ method was performed.

Each of FIGS. 16 to 19 is a diagram showing an example of the θ-2θ spectrum by the XRD method of the film structure formed up to the PZT film. The horizontal axis of each of the graphs of FIGS. 16 to 19 shows the angle 2θ, and the vertical axis of each of the graphs of FIGS. 16 to 19 shows the intensity of the X-ray. 16 and 17 show the results for Example 1, and FIGS. 18 and 19 show the results for Comparative Example 1. FIG. Figures 16 and 18 show 20° The range of ≦2θ≦50°, Fig. 17 and Fig. 19 show the range of 90°≦2θ≦110°.

In the example (Example 1) shown in FIGS. 16 and 17 , in the θ-2θ spectrum, peaks corresponding to the (200) plane and (400) plane of Pt having a cubic crystal structure, and peaks corresponding to the (200) plane and (400) plane of Pt having a cubic crystal structure The peaks of the (001) plane, (002) plane and (004) plane of PZT were observed. Therefore, in the example shown in FIGS. 16 and 17 (Example 1), the conductive film 13 includes a tetragonal crystal structure and Pt with a (100) orientation, and the piezoelectric film 15 includes a cubic crystal and is shown as (001) Aligned PZT.

In addition, in the example shown in FIG. 17 (Example 1), when the diffraction angle of the diffraction peak of the (004) plane represented by the tetragonal crystal of PZT is 2θ ₀₀₄ , it is 2θ ₀₀₄ =96.5°. Therefore, in the example (Example 1) shown in FIGS. 16 and 17 , 2θ ₀₀₄ satisfies 2θ ₀₀₄ ≦96.5°, and it can be seen that the aforementioned formula (Equation 1) is satisfied.

Even in the example (Comparative Example 1) shown in FIGS. 18 and 19 , as in the example (Example 1) shown in FIGS. 16 and 17 , the θ-2θ spectrum corresponds to a crystal structure having a cubic crystal structure. Peaks on the (200) plane and (400) plane of Pt, and peaks corresponding to the (001) plane, (002) plane, and (004) plane of PZT having a tetragonal crystal display were observed. Therefore, even in the example shown in FIGS. 18 and 19 (Comparative Example 1), as in the example shown in FIGS. 16 and 17 (Example 1), the conductive film 13 has a tetragonal crystal structure, and (100) oriented Pt, the piezoelectric film 15 includes PZT whose cubic crystals exhibit (001) orientation.

However, in the example shown in FIG. 19 (comparative example), unlike the example shown in FIG. 17 (Example 1), when the diffraction angle of the diffraction peak of the (004) plane represented by the tetragonal crystal of PZT is 2θ ₀₀₄ , is 2θ ₀₀₄ =96.7°. Therefore, in the example (Comparative Example 1) shown in FIGS. 18 and 19 , it can be seen that 2θ _{004 does} not satisfy 2θ ₀₀₄ ≦96.5°, and the aforementioned formula (Equation 1) is not satisfied.

In Example 1, the measurement of the pole diagram by the XRD method was performed, and the relationship between the in-plane orientations of the films of each layer was investigated. Each of FIGS. 20-23 is a figure which shows the example of the pole figure by the XRD method of the film structure of Example 1. Fig. 20 is a pole diagram of Si(220) plane, Fig. 21 is a pole diagram of ZrO ₂ (220) plane, Fig. 22 is a pole diagram of Pt(220) plane, and Fig. 23 is a pole diagram of PZT(202) plane.

As described above, the alignment film 12 has a cubic crystal structure and includes a (100) alignment zirconia film 12a (see FIG. 7 ). In such a case, as shown in FIGS. 20 and 21 , it can be understood that the zirconia film 12a is connected to the substrate in the <100> direction along the upper surface 11a of the main surface of the substrate 11 made of the silicon substrate of the zirconia film 12a. The <100> direction of the upper surface 11a of the 11 itself is aligned so as to be parallel. In other words, it can be understood that the zirconia film 12a is along the <110> direction of the upper surface 11a of the main surface of the substrate 11 composed of the silicon substrate of the zirconia film 12a and the <110> direction of the upper surface 11a of the substrate 11 itself. The directions become aligned in such a way that they are parallel.

In addition, the conductive film 13 has a cubic crystal structure and includes a platinum film 13a of (100) orientation (see FIG. 7 ). In such a case, as shown in FIGS. 20 and 22, it can be understood that the platinum film 13a is along the <100> direction of the upper surface 11a of the substrate 11 made of the silicon substrate of the platinum film 13a and the upper surface 11a of the substrate 11 itself. The <100> direction is aligned so as to be parallel. Change In other words, it can be understood that the platinum film 13a is aligned so that the <110> direction of the upper surface 11a of the upper surface 11a of the substrate 11 composed of the silicon substrate of the platinum film 13a is parallel to the <110> direction of the upper surface 11a of the substrate 11 itself .

In addition, the piezoelectric film 15 has a tetragonal crystal structure and includes a lead titanate zirconate film 15a having a (001) orientation. In such a case, as shown in FIG. 20 and FIG. 23 , it can be seen that the lead titan zirconate film 15a is connected to the substrate in the <100> direction along the upper surface 11 a of the substrate 11 made of the silicon substrate of the lead titan zirconate film 15a. The <100> direction of the upper surface 11a of the 11 itself is aligned so as to be parallel. In other words, it can be understood that the lead titanozirconate film 15a is along the <110> direction of the upper surface 11a of the substrate 11a composed of the silicon substrate of the lead titanozirconate film 15a, and the <110> direction of the upper surface 11a of the substrate 11 itself. The directions become aligned in such a way that they are parallel.

For Example 1, film structures up to the PZT film as the piezoelectric film 17 were formed on each of the 17 wafers of No. 1 to No. 17 under the same conditions, and the ratio of the formed film structures was measured. Theta-2theta spectrum according to XRD method. That is, X-ray diffraction measurement by the θ-2θ method was performed on the 17-piece film structure as Example 1.

24 is a diagram showing the diffraction angle 2θ ₀₀₄ of the respective X-ray diffraction patterns formed on the film structures formed on each of the 17 wafers of No. 1 to No. 17 of Example 1. FIG. In FIG. 24 , the diffraction angle 2θ ₀₀₄ of a certain film structure is shown on the left side, and the diffraction angle 2θ ₀₀₄ at the outer periphery of the _wafer is shown on the right side.

As shown in FIG. 24 , in each of the film structures formed on the 17 wafers of Example 1, the diffraction angle 2θ ₀₀₄ was larger than 95.9° and smaller than 96.4°. That is, it can be seen that the 17 wafers of Example 1 have the diffraction angle 2θ ₀₀₄ , which satisfies the aforementioned formula (Equation 1).

In addition, with respect to Example 1, the film structure up to the PZT film as the piezoelectric film 17 was further formed on each of the 12 wafers of No. 21 to No. 32 under the same conditions, and the formed films were measured. Theta-2Θ spectrum of the structure according to the XRD method. That is, X-ray diffraction measurement by the θ-2θ method was performed for the 12-piece film structure as Example 1.

25 is a diagram showing the diffraction angle 2θ ₀₀₄ of the respective X-ray diffraction patterns formed on the film structures formed on each of the 12 wafers of No. 21 to No. 32 of Example 1. FIG. In FIG. 25 , similarly to FIG. 24 , the diffraction angle 2θ ₀₀₄ at the center of the wafer is shown on the left, and the diffraction angle 2θ ₀₀₄ at the outer periphery of the wafer is shown at the diffraction angle 2θ ₀₀₄ of a certain film structure. Right.

As shown in FIG. 25 , in each of the film structures formed on the 12 wafers of Example 1, the diffraction angle 2θ ₀₀₄ was larger than 96.0° and smaller than 96.25°. That is, it can be seen that the 17 wafers of Example 1 have the diffraction angle 2θ ₀₀₄ , which satisfies the aforementioned formula (Equation 1).

In addition, in the θ-2θ spectrum of FIGS. 18 and 19 , the tetragonal crystal of PZT is represented by the high-angle side of the (00n) plane (n is a natural number), and a peak is observed. This is probably because, for example, a portion of PZT having a tetragonal crystal structure with a (100) orientation has a small content rate, and this portion functions as a stress relaxation layer.

Next, as shown in FIG. 2 , a platinum (Pt) film was formed on the piezoelectric film 15 as a conductive film 18 by a sputtering method. After that, a voltage was applied between the conductive film 13 and the conductive film 18, and the voltage dependence of polarization was measured.

FIG. 26 is a graph showing the voltage dependence of polarization of the membrane structure of Example 1. FIG. FIG. 27 is a graph showing the voltage dependence of polarization of the membrane structure of Comparative Example 1. FIG. The horizontal axis of each of the graphs of FIGS. 26 and 27 shows voltage, and the vertical axis of each of the graphs of FIGS. 26 and 27 shows polarization (the same applies to the following graphs showing the voltage dependence of polarization).

According to FIG. 26 , in the film structure of Example 1, the relative permittivity ε _r was 450 or less (measured value 450), and the residual extreme value _Pr was 28 μC/cm ² or more (measured value 28 μC/cm ² ). In addition, when a cantilever was formed and the piezoelectric constant d ₃₁ was measured using the formed cantilever, the piezoelectric constant d ₃₁ was 200 pm/V.

On the other hand, according to FIG. 27 , in the film structure of Comparative Example 1, the relative permittivity ε _r exceeded 450 (measured value 800), and the residual extreme value Pr was less than 28 μC/cm ² (measured value 10 μC/cm 2 ₎ . ² ). In addition, when the piezoelectric constant d ₃₁ was measured in the same manner as in Example 1, the piezoelectric constant d ₃₁ was 140 pm/V. As described above, in the method of forming the film structure of Comparative Example 1, when the piezoelectric film 16 was formed using the RF sputtering apparatus, the high-frequency power (power) supplied was 2750 W, which was different from the high-frequency power supplied. The conditions for Example 1, which is 2250W, are different.

That is, according to Example 1 and Comparative Example 1, it can be understood that in the film structure of the present embodiment, when the high-frequency power supplied when the piezoelectric film 16 is formed is within a certain range, the relative permittivity _εr satisfies the above-mentioned value. Equation (Equation 2), the residual extreme value P _r satisfies the aforementioned Equation (Equation 3). Here, in the following, the film structures of Examples 2 to 9 and Comparative Example 2 were formed, and the relative permittivity ε _r satisfies the aforementioned formula (Equation 2) and the residual extreme value Pr satisfies the aforementioned formula (Equation 2) in detail. condition of formula 3).

(Example 2 and Example 3)

The production method of the film structure of Example 1 was carried out in the same manner as the production method of the film structure of Example 1, except that the substrate temperature at the time of forming the piezoelectric film 16 was changed from 425° C. to 450° C., and an example was formed. 2. Membrane structure. In addition, the method of manufacturing the film structure of Example 1 was performed in the same manner as the method of manufacturing the film structure of Example 1, except that the substrate temperature at the time of forming the piezoelectric film 16 was changed from 425°C to 475°C. The membrane structure of Example 3.

With respect to the film structures of Example 2 and Example 3, the voltage dependence of polarization was measured by applying a voltage between the conductive film 13 and the conductive film 18 . FIG. 28 is a graph showing the voltage dependence of polarization of the membrane structure of Example 2. FIG. FIG. 29 is a graph showing the voltage dependence of polarization of the membrane structure of Example 3. FIG.

According to FIG. 28 , in the film structure of Example 2, the relative permittivity ε _r was 450 or less, and the residual extreme value _Pr was 28 μC/cm ² or more (actually measured value 41 μC/cm ² ). 29 , in the film structure of Example 3, the relative permittivity ε _r was 450 or less, and the residual extreme value _Pr was 28 μC/cm ² or more (actually measured value 45 μC/cm ² ).

That is, according to Examples 1 to 3, it can be seen that when the supplied high-frequency power is 2250W, the substrate temperature when the piezoelectric film 16 is formed is in the range of 425 to 475°C, and the relative permittivity of 450 or less can be obtained. ε _r , the residual extreme value P _r of 28 μC/cm ² or more can be obtained. In addition, although detailed description is omitted, when the substrate temperature when the piezoelectric film 16 is formed is less than 425°C, or when the substrate temperature when the piezoelectric film 16 is formed exceeds 475°C, a relative permittivity of 450 or less is obtained. _εr is difficult.

(Example 4 and Example 5)

The method of manufacturing the film structure of Example 1 was performed in the same manner as the method of manufacturing the film structure of Example 1, except that the high-frequency power (power) supplied when the piezoelectric film 16 was formed was changed from 2250W to 2000W, The membrane structure of Example 4 was formed. At this time, the film-forming speed was 0.20 nm/s, which was smaller than 0.29 nm/s in Example 1.

In addition, the manufacturing method of the membrane structure of Example 1 is the same as the manufacturing method of the membrane structure of Example 1, except that the high-frequency electric power (power) supplied when the piezoelectric film 16 is formed is changed from 2250 W to 1750 W Then, the membrane structure of Example 5 was formed. At this time, the film-forming speed was 0.17 nm/s, which was smaller than 0.29 nm/s in Example 1.

For the film structures of Examples 4 and 5, the voltage dependence of polarization was measured by applying a voltage between the conductive film 13 and the conductive film 18 . FIG. 30 is a graph showing the voltage dependence of polarization of the membrane structure of Example 4. FIG. FIG. 31 is a graph showing the voltage dependence of polarization of the membrane structure of Example 5. FIG.

According to FIG. 30 , in the film structure of Example 4, the relative permittivity ε _r was 450 or less, and the residual extreme value _Pr was 28 μC/cm ² or more (actually measured value 45 μC/cm ² ). 31 , in the film structure of Example 5, the relative permittivity ε _r was 450 or less, and the residual extreme value _Pr was 28 μC/cm ² or more (actually measured value 50 μC/cm ² ).

That is, according to Example 1, Example 4 and Example 5, it can be seen that when the substrate temperature is 425° C., the high-frequency power supplied when the piezoelectric film 16 is formed is in the range of 1750 to 2250 W, and 450 or less can be obtained. Relative permittivity ε _r , the residual fractional extreme value P _r above 28 μC/cm ² can be obtained. This should be because the high-frequency power is in the range of 1750~2250W. The smaller the value of the high-frequency power, the slower the film formation speed and the slow crystal growth of the piezoelectric film 16, which improves the single crystallinity of the piezoelectric film 16 and improves the Residual sub-extreme value _Pr 's sake.

(Example 6 to Example 8 and Comparative Example 2)

The method of manufacturing the film structure of Example 1 is the same as the method of manufacturing the film structure of Example 1, except that the value of the high-frequency electric power (power) supplied when the piezoelectric film 16 is formed is changed from 2250 W to 2500 W Then, the film structure of Comparative Example 2 was formed. These conditions are shown in FIG. 32 . In addition, FIG. 32 is a table showing the measurement results of the film formation conditions of Example 1, Example 6 to Example 8, Comparative Example 1 and Comparative Example 2, and the diffraction angle 2θ ₀₀₄ of PZT, relative permittivity ε _r , etc. .

In addition, in the method of manufacturing the film structure of Example 1, except for the high-frequency power (power) supplied at the time of forming the piezoelectric film 16, the high-frequency power supplied in the subsequent step is higher than that in the preceding step. The value of the high-frequency power to be supplied is even smaller, except that the value of the high-frequency power to be supplied is divided into a plurality of steps, and the value is changed in the same manner as in the production method of the membrane structure of Example 1, and the membrane structures of Examples 6 to 8 are formed. body.

As described above, the reason why the high-frequency power is divided into a plurality of steps to change its value and supply it is because in the step of forming the piezoelectric film 16, if the value of the high-frequency power supplied first is reduced and the film formation speed is reduced, mass productivity is improved. will decrease. On the other hand, by slowly growing only the upper layer portion of the piezoelectric film 16, As a whole, it is possible to obtain the piezoelectric film 16 having a good single crystal form at a relatively fast film-forming rate, and to obtain good ferroelectric properties.

Specifically, in the manufacturing method of the film structure of Example 6, in the step of forming the piezoelectric film 16, in the first step, the value of the supplied high-frequency power was set to 2250W, and the substrate temperature was set to 450°C. The film formation time was 2100 s, and a Pb(Zr _0.58 Ti _0.42 )O ₃ film (lower PZT film) having a film thickness of 500 nm was formed. Next, in the step of forming the piezoelectric film 16, in the second step, the value of the supplied high-frequency power was set to 2000 W, the substrate temperature was set to 450° C., and the film formation time was set to 2300 s to form a Pb film having a thickness of 500 nm. (Zr _0.58 Ti _0.42 )O ₃ film (upper PZT film). Thereby, the piezoelectric film 16 composed of the lower-layer PZT film and the upper-layer PZT film is formed. These conditions are shown in FIG. 32 . In addition, in FIG. 32, only the value (2000W) of the step of forming the upper layer PZT film is shown as a high frequency electric power.

In addition, in the method for producing the film structure of Example 7, among the steps of forming the piezoelectric film 16, in the first step, the value of the supplied high-frequency power was set to 2250 W, the substrate temperature was set to 450° C., and the film was formed. The time was 4200 s, and a Pb(Zr _0.58 Ti _0.42 )O ₃ film (lower PZT film) having a film thickness of 1 μm was formed. Next, in the step of forming the piezoelectric film 16, in the second step, the value of the supplied high-frequency power was set to 1750 W, the substrate temperature was set to 450° C., and the film formation time was set to 2300 s to form a Pb film having a thickness of 500 nm. (Zr _0.58 Ti _0.42 )O ₃ film (middle layer PZT film). Furthermore, in the step of forming the piezoelectric film 16, in the third step, the value of the supplied high-frequency power was set to 1750 W, the substrate temperature was set to 425°C, and the film formation time was set to 2300 s to form Pb having a film thickness of 500 nm. (Zr _0.58 Ti _0.42 )O ₃ film (upper PZT film). Thereby, the piezoelectric film 16 composed of the lower-layer PZT film, the middle-layer PZT film, and the upper-layer PZT film is formed. The total film-forming time was 8800 s. These conditions are shown in FIG. 32 . In addition, in FIG. 32, as a high frequency electric power, only the value (1750W) of the step of forming an upper layer PZT film is shown.

In addition, in the method for producing the film structure of Example 8, among the steps of forming the piezoelectric film 16, in the first step, the value of the supplied high-frequency power was set to 1750 W, the substrate temperature was set to 450° C., and the film was formed. The time was 2300 s, and a Pb(Zr _0.58 Ti _0.42 )O ₃ film (lower PZT film) having a film thickness of 500 nm was formed. Next, in the step of forming the piezoelectric film 16, in the second step, the value of the supplied high-frequency power was set to 1750 W, the substrate temperature was set to 425° C., and the film formation time was set to 2100 s, and a Pb film having a thickness of 400 nm was formed. (Zr _0.58 Ti _0.42 )O ₃ film (middle layer PZT film). Furthermore, in the step of forming the piezoelectric film 16 , in the third step, the value of the supplied high-frequency power was set to 1500 W, the substrate temperature was set to 475° C., and the film formation time was set to 900 s to form Pb having a film thickness of 100 nm. (Zr _0.58 Ti _0.42 )O ₃ film (upper PZT film). Thereby, the piezoelectric film 16 composed of the lower-layer PZT film, the middle-layer PZT film, and the upper-layer PZT film is formed. The total film-forming time was 5300 s. These conditions are shown in FIG. 32 . In addition, in FIG. 32, only the value (1500W) of the step of forming the upper layer PZT film is shown as a high frequency electric power.

For each of Examples 6 to 8, the θ-2θ spectrum by the XRD method of the film structure up to the PZT film formed as the piezoelectric film 17 was measured. That is, for each of Examples 6 to 8, X-ray diffraction measurement by the θ-2θ method was performed.

Each of FIGS. 33 to 35 shows the film formed up to the PZT film A graph showing an example of the θ-2θ spectrum of the structure according to the XRD method. The horizontal axis of each of the graphs of FIGS. 33 to 35 shows the angle 2θ, and the vertical axis of each of the graphs of FIGS. 16 to 19 shows the intensity of X-rays. Figure 33 shows the results for Example 6, Figure 34 shows the results for Example 7, and Figure 35 shows the results for Example 8. 33 to 35 show the range of 90°≦2θ≦110°.

Furthermore, 2θ ₀₀₄ obtained in FIGS. 17 , 19 , and 33 to 35 is shown in FIG. 32 . In addition, although the illustration of the θ-2θ spectrum is omitted, in the film structure of Comparative Example 2, 2θ ₀₀₄ obtained by measuring the θ-2θ spectrum by the XRD method is also shown in FIG. 32 .

As shown in FIGS. 33 to 35 and 32 , in the membrane structure of Example 6, 2θ ₀₀₄ =96.4°, the membrane structure of Example 7, 2θ ₀₀₄ =96.1°, and the membrane structure of Example 8, 2θ ₀₀₄ =95.9°. In addition, as described above, in the film structure of Example 1, 2θ ⁰⁰⁴ = 96.5°, and the detailed description is omitted, but in the film structure of Examples 2 to 5, 2θ ₀₀₄ satisfies 2θ ₀₀₄ ≦96.5°. Therefore, in the film structures of Examples 1 to 8, 2θ ₀₀₄ satisfies 2θ ₀₀₄ ≦96.5°, and it can be seen that the aforementioned formula (Equation 1) is satisfied.

In addition, with respect to the film structures of Comparative Example 2 and Examples 6 to 8, the voltage dependence of polarization was measured by applying a voltage between the conductive film 13 and the conductive film 18 . FIG. 36 is a graph showing the voltage dependence of polarization of the membrane structure of Comparative Example 2. FIG. FIG. 37 is a graph showing the voltage dependence of polarization of the membrane structure of Example 6. FIG. FIG. 38 is a graph showing the voltage dependence of polarization of the membrane structure of Example 7. FIG. FIG. 39 is a graph showing the voltage dependence of polarization of the membrane structure of Example 8. FIG.

According to FIGS. 36 and 32 , in the film structure of Comparative Example 2, the relative permittivity _εr exceeds 450 (measured value 580), and the residual extreme value Pr is less than 28 μC/cm ² (measured value 18 μC/cm 2 ₎ . ² ). In addition, when a cantilever was formed and the piezoelectric constant d ₃₁ was measured using the formed cantilever, the piezoelectric constant d ₃₁ was 178 pm/V.

According to FIGS. 37 and 32 , in the film structure of Example 6, the relative permittivity ε _r is 450 or less (measured value 330), and the residual extreme value Pr is 28 μC/cm ² or more (measured value 39 μC/cm 2 ₎ . ² ). Further, when the piezoelectric constant d ₃₁ was measured in the same manner as in Comparative Example 2, the piezoelectric constant d ₃₁ was 210 pm/V.

In addition, according to FIGS. 38 and 32 , in the film structure of Example 7, the relative permittivity ε _r is 450 or less (actually measured value 263), and the residual extreme value P _r is 28 μC/cm ² or more (actually measured value 48 μC /cm ² ). Further, when the piezoelectric constant d ₃₁ was measured in the same manner as in Comparative Example 2, the piezoelectric constant d ₃₁ was 220 pm/V.

In addition, according to FIGS. 39 and 32 , in the film structure of Example 8, the relative permittivity ε _r was 450 or less (measured value 216), and the residual extreme value P _r was 28 μC/cm ² or more (measured value 57 μC /cm ² ). Further, when the piezoelectric constant d ₃₁ was measured in the same manner as in Comparative Example 2, the piezoelectric constant d ₃₁ was 230 pm/V.

That is, according to Examples 1 to 8, the relative permittivity ε _r satisfies ε _r ≦450, the residual extreme value _Pr satisfies _Pr ≧ 28 μC/cm ² , and the piezoelectric constant d ₃₁ satisfies d ₃₁ ≧ 200pm /V, it can be seen that the aforementioned formula (Formula 1) and formula (Formula 2) are satisfied.

As described above, PZT also lowers the relative permittivity by improving the crystallinity including the orientation of the thin film, similarly to PbTiO ₃ . That is, in Examples 1 to 8, the relative permittivity ε _r was as low as 450 or less, indicating that the piezoelectric film 15 became a single crystal.

The so-called piezoelectric phenomenon is that when stress is applied to the piezoelectric body, the The crystal lattice is deformed, and the piezoelectric body generates charges corresponding to the deformation. That is, the piezoelectric deformation is a value obtained by dividing the charge density generated in the piezoelectric body by the stress applied to the piezoelectric body, and in the case of the piezoelectric body being a ferroelectric, it is proportional to the residual extreme value.

In addition, the capacitance of a capacitor composed of a dielectric body and two electrodes formed above and below the dielectric body is proportional to the relative permittivity of the dielectric body and the area of each of the two electrodes, but is proportional to the dielectric body's relative permittivity and the area of each of the two electrodes. The thickness of , that is, the distance between the two electrodes is inversely proportional. In this case, and the above-mentioned case where electric charges are generated when stress is applied to the piezoelectric body, the piezoelectric deformation ratio is proportional to the relative permittivity of the dielectric body composed of the piezoelectric body.

In Comparative Example 1 and Comparative Example 2, and Example 1 and Example 6 to Example 8, when the product of the residual extreme value Pr and the relative permittivity ε _r (P _r ·ε _r ) was obtained, as shown in Fig. 32 It can be seen that the value of P _r ·ε _r has a good proportional relationship with the piezoelectric constant d ₃₁ . That is, as described above, it was confirmed that the piezoelectric strain is proportional to the residual extreme value and also proportional to the relative permittivity.

In addition, the fractured surface was observed by SEM. As a result, detailed descriptions are omitted, but the piezoelectric film 16 has good single crystallinity compared to the first and sixth to eighth examples. In Comparative Examples 1 and 2, the piezoelectric film 16 and Cracks (cracks) extending in the thickness direction of the piezoelectric film 16 were observed between two crystal grains adjacent in the direction of the main surface, and it was found that the single crystallinity of the piezoelectric film 15 was lowered. In FIG. 32 , when cracks are observed, it is indicated by ×, and when no cracks are observed, it is indicated by ○.

From the above results, it can be seen that the piezoelectric film included in the film structure can obtain a high-quality single crystal film by satisfying the above-mentioned equations (Equation 1) and Equation (Equation 2). The piezoelectric film formed can reduce the relative permittivity of the piezoelectric film and improve the piezoelectric characteristics of the piezoelectric film, so the piezoelectric characteristics of the piezoelectric film can be improved, and the pressure sensitivity of the piezoelectric film can be improved. The detection sensitivity of the detector.

(Example 9 and Example 10)

The membrane structure of Example 9 was formed in the same manner as in the method for producing the membrane structure of Example 1. In addition, the method for producing the film structure of Example 1 was performed in the same manner as the method for producing the film structure of Example 1, except that the composition of PZT was changed from x=0.42 to x=0.48, to form the film structure of Example 10. Membrane constructs. For the film structures of Examples 9 and 10, the voltage dependence of polarization was measured by applying a voltage between the conductive film 13 and the conductive film 18 . FIG. 40 is a graph showing the voltage dependence of polarization of the membrane structure of Example 9. FIG. FIG. 41 is a graph showing the voltage dependence of polarization of the membrane structure of Example 10. FIG.

In addition, Table 2 shows the results of measuring the ferroelectric properties, piezoelectric properties, and the like of Examples 9 and 10. In Table 2, the residual extreme value P _r , the relative dielectric constant ε _r , the dielectric tangent tanδ, the piezoelectric constant d ₃₁ , the piezoelectric constant g ₃₁ , the piezoelectric constant e ₃₁ , and the film thickness are shown. In addition, in Table 2, the piezoelectric constant d ₃₁ , the piezoelectric constant g ₃₁ , and the piezoelectric constant e ₃₁ are not absolute values, but are represented by signs.

As shown in Fig. 40 and Table 2, when x=0.42 (Example 9 ₎ , the residual fractional extreme value Pr is 50 μC/cm ² , the relative permittivity ε _r is 200, the tanδ is 0.01%, and the piezoelectric constant d ₃₁ was -200 pm/V, the piezoelectric constant g ₃₁ was -100×10 ³ Vm/N, and the piezoelectric constant e ₃₁ was -25 C/m ² , and good characteristics were obtained. In addition, as shown in Fig. 41 and Table 2, even in the case of x=0.48, the residual extreme value P _r is 60 μC/cm ² , the relative permittivity ε _r is 300, the tanδ is 0.01%, and the piezoelectric constant d ₃₁ The piezoelectric constant g 31 was -250 pm/V, the piezoelectric constant g ₃₁ was -80×10 ³ Vm/N, and the piezoelectric constant e ₃₁ was -27 C/m ² , and good characteristics were obtained. In addition, although a detailed description is abbreviate|omitted, when the value of x is changed in the range of 0.32≦x≦0.52, good characteristics can be obtained. From the above results, it is clear that when x=0.42 and 0.48 are included, good characteristics are obtained in the range of 0.32≦x≦0.52.

As mentioned above, the invention made by the present inventors has been specifically described based on its embodiments, but the present invention is not limited to the above-mentioned embodiments, and various modifications can of course be made without departing from the gist of the invention.

Within the scope of the idea of the present invention, those skilled in the art (manufacturers) can think of various modifications and corrections, and these modifications and corrections should be understood as belonging to the scope of the present invention.

For example, for each of the above-mentioned embodiments, those skilled in the art make appropriate additions, deletions, or design changes of constituent elements, or additions, omissions, or conditions change of steps, as long as the gist of the present invention is satisfied. included in the scope of the present invention.

20: Film forming device

21: Vacuum Chamber

21a: Bottom plate

21b, 21e: side plate

21c, 21f: top plate

21d: Cover

22: Vacuum exhaust part

23, 24: Gas supply part

23a, 24a: flow controller

23b, 24b: Gas supply pipes

25: Substrate holding part

26: Support Department

27: Rotary drive part

28: Substrate heating section

29: Anti-adhesion plate

29a: Cooling pipe

31: Target holding part

32: Power Supply Department

32a: High frequency power supply

32b: Integrator

33: V _DC control part

34: Magnet Department

35: Magnet rotating drive part

41, 42, 45, 46, 47: Conductive members

43, 56: Screws

44: Slip Ring

51, 52, 53, 54, 55: Insulating members

BP1: backing plate (backing: plate)

CE1: Sealing part

OP1, OP2, OP3: Opening

RA1: Rotary axis

SB: Substrate

TG: target

TM1: Target

Claims (6)

A membrane construct comprising: a silicon substrate with a main surface consisting of (100) surfaces, and a first film formed on the aforementioned silicon substrate and comprising a (100) oriented zirconia film; The zirconia film is aligned so that the <100> direction along the main surface of the zirconia film and the <100> direction along the main surface of the silicon substrate become parallel. The film structure of claim 1, further comprising a conductive film formed on the first film and comprising a (100)-oriented metal film; The metal film is aligned so that the <100> direction along the main surface of the metal film is parallel to the <100> direction along the main surface of the silicon substrate. The film structure of claim 2, further comprising a piezoelectric film on the conductive film; The piezoelectric film is aligned so that the <100> direction along the main surface of the piezoelectric film is parallel to the <100> direction along the main surface of the silicon substrate. The film structure of claim 3, wherein the piezoelectric film includes a (001) oriented lead zirconate titanate film. According to the film structure of claim 4, the lead titanate zirconate film has a composite oxide composed of lead titanate zirconate represented by the following general formula (chemical formula 1): Pb(Zr _1-x Ti _x )O ₃ ...... (chemical formula 1) The aforementioned x satisfies 0.32≦x≦0.52. The film structure according to any one of claims 2 to 5, wherein the metal film is a platinum film.

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