WO2007119643A1

WO2007119643A1 - Film bulk acoustic resonator, piezoelectric thin film device and method for manufacturing the piezoelectric thin film device

Info

Publication number: WO2007119643A1
Application number: PCT/JP2007/057379
Authority: WO
Inventors: Tetsuo Yamada; Keigo Nagao
Original assignee: Ube Industries, Ltd.
Priority date: 2006-03-31
Filing date: 2007-04-02
Publication date: 2007-10-25
Also published as: JPWO2007119643A1; JP4688070B2

Abstract

A film bulk acoustic resonator (10) includes substrates (11, 12) having an oscillation space (20), and a piezoelectric laminated structure (14) arranged to face the oscillation space (20). The piezoelectric laminated structure (14) is provided with at least a lower electrode (15), a piezoelectric thin film (16) and an upper electrode (17), which are arranged in sequence from the side close to the oscillation space (20). A lower insulating layer (13) is formed in contact with the lower surface of the lower electrode (15), and an upper insulating layer (23) is formed in contact with the lower surface of the upper electrode (17). A side spacer (26) made of a material different from that of the electrode is arranged on the outer circumference of the lower electrode (15) and the upper electrode (17). A step on an interface between the side spacer (26) and the electrodes (15, 17) is less than 25nm. The piezoelectric thin film (16) is composed of aluminum nitride. The acoustic impedance of the side spacer (26) is larger than the acoustic impedances of the electrodes (15, 17).

Description

Specification

Piezoelectric thin film resonator, piezoelectric thin film device, and manufacturing method thereof

Technical field

[0001] The present invention relates to a piezoelectric thin film used in a wide range of fields such as a thin film resonator, a thin film VCO (voltage controlled oscillator), a thin film filter, a transmission / reception switch, and various sensors used in mobile communication devices. The present invention relates to a resonator and a piezoelectric thin film device which is an element to which the resonator is applied.

Background art

[0002] Devices using the piezoelectric phenomenon are used in a wide range of fields. As mobile devices become smaller and labor-saving, surface acoustic waves (Surface Acoustic) are used as RF and IF filters.

The use of Wave (SAW) elements is expanding. SAW filters have been able to meet the user's strict requirements by improving design and production technology, and approaching the limit of improvement in characteristics along with the high frequency of use frequency, a major technology in both miniaturization of electrode formation and ensuring stable output Innovation is needed. On the other hand, thin film bulk acoustic wave resonators (hereinafter referred to as FB AR, Solidly Mounted Bulk Acoustic Wave Resonator: hereinafter referred to as SMR), layered thin film bulk acoustic wave resonators and Filter (Stacked Thin Film Bulk Wave

Acoustic Resonators and Filters (hereinafter referred to as SBAR) is a thin support film provided on a substrate, on which a thin film consisting mainly of a piezoelectric material and an electrode that drives it are formed. Basic resonance in the gigahertz band Is possible. If the filter is configured with FBAR, SMR or SBAR, it can be remarkably miniaturized, and it can operate in a low loss 'broadband' and can be integrated with a semiconductor integrated circuit. Application to is expected.

[0003] Piezoelectric thin film elements such as FBARs, SMRs, and SBARs that are applied to resonators and filters that use elastic waves are manufactured as follows. A dielectric thin film, a conductive thin film, or these layers are laminated on a substrate made of a semiconductor single crystal such as silicon and a substrate formed of polycrystalline diamond on a silicon wafer by various thin film forming methods. Forms a basement film. A piezoelectric thin film is formed on this base film, and if necessary, Forming a superstructure. After each layer is formed, or after all layers are formed, each film is subjected to physical processing or chemical processing to perform fine processing or patterning. The substrate portion located below the vibration region is removed by anisotropic etching to produce a floating structure, and finally, the piezoelectric thin film element is obtained by separating into one element unit.

[0004] For example, a piezoelectric thin film element (FBAR) described in Patent Document 1 is under a portion that becomes a vibration region after forming a base film, a lower electrode, a piezoelectric thin film, and an upper electrode on a substrate. Manufactured by removing the substrate back side force to form a vibration space. Piezoelectric materials for piezoelectric thin film elements include aluminum nitride (A1N), acid zinc (ZnO), nickel cadmium sulfate (CdS), lead titanate (PT (PbTiO;)), and lead zirconate titanate ( P

Three

ZT (Pb (Zr, Ti) 0)) or the like can be used. A1N in particular has a propagation velocity of elastic waves.

Three

It is suitable as a piezoelectric material for thin film resonators and thin film filters that operate in a fast high frequency band.

[0005] Patent Document 2 describes the configuration and manufacturing method of an air bridge type FBARZSBAR device. According to the publication, first, phosphor quartz glass (PSG) is deposited as a sacrificial layer on a silicon wafer, and after CMP, a piezoelectric resonator is fabricated on the sacrificial layer. PSG can be deposited at relatively low temperatures and diluted H

2

0: Etched with HF solution at very high etching rate. Therefore, the sacrificial layer is etched away near or at the end of the process to form a vibration region. Since all processing takes place on the front side of the wafer, this method does not require pattern alignment on both sides of the wafer and a large area wafer backside opening.

[0006] Instead of providing an air Z crystal interface, there is a method of providing an appropriate acoustic mirror. In this method, as described in Patent Document 3, for example, a large acoustic impedance, which is an acoustic Bragg reflector force, is created under a sandwich structure composed of a lower electrode, a piezoelectric thin film, and an upper electrode. Bragg reflectors are made by alternately stacking layers of high acoustic impedance material and low acoustic impedance material. The thickness of each layer is fixed at 1Z4 at the wavelength of the resonance frequency. By forming a laminated film with a sufficient number of layers, the effective impedance at the piezoelectric Z-electrode interface can be made much higher than the acoustic impedance of the element, so that the acoustic waves in the piezoelectric body can be effectively confined. Can. The low acoustic impedance layer can also be composed of silicon oxide or aluminum forces, and the high acoustic impedance layer can be composed of tungsten, platinum, molybdenum or gold. The acoustic resonator obtained by this method is called a solid acoustic mirror mounted resonator (SMR) because there is no air gap under the sandwich structure.

[0007] Although the structure and manufacturing method of the piezoelectric thin film resonator with the above! / Is shifted, the lower electrode, the piezoelectric thin film, and the upper electrode are still formed in this order. It is also possible to realize a five-layer structure in which an insulator layer is provided below the lower electrode and above the upper electrode, and the insulator layer Z lower electrode Z piezoelectric thin film Z upper electrode Z insulator layer is formed on the semiconductor substrate. Generally adopted. Furthermore, it is also known that an insulator layer provided below the lower electrode is used as a seed layer for crystal growth, and an insulator layer provided above the upper electrode is used as a protective layer.

[0008] Various improvements have been attempted in methods for forming thin films such as A1N and ZnO used as piezoelectric thin films, such as electromechanical coupling coefficient, acoustic quality factor (Q value), and frequency temperature coefficient. It is desired to form a highly oriented and homogeneous piezoelectric thin film with excellent piezoelectric properties. It is known that the quality of the A1N thin film formed by a thin film forming method such as reactive sputtering is strongly influenced by the properties of the underlying layer on which A1N is deposited. According to Patent Document 4 by the present inventors, in forming the A1N thin film, the RMS fluctuation of the height of the surface of the lower electrode serving as the underlayer is controlled to 50 nm or less, preferably 20 nm or less, and the surface of the lower electrode is remarkably increased. By making it flat, a highly oriented A1N thin film can be deposited. According to the X-ray diffraction measurement of the obtained A1N thin film, the rocking curve half-width (FWHM) of the (0002) diffraction peak is less than 3.0 °, which indicates good piezoelectric characteristics.

[0009] Patent Document 4 describes that a pattern of a lower electrode is formed by a lift-off method. Inevitably, this causes a gentle inclination, for example, an inclination having a taper angle of less than 10 °, at the outer peripheral portion of the lower electrode. Here, the taper angle is an angle (inclination angle) between the upper surface of the outer periphery of the lower electrode and the lower surface (that is, a surface in contact with the base insulating layer and parallel to the silicon substrate).

[0010] On the other hand, when the electrode pattern is formed by wet etching, the outer periphery thereof has a steep inclination with a taper angle of 70 ° or more. Piezoelectric thin film with a steep inclination angle An example of a membrane resonator is shown in FIG. 1A is a schematic plan view showing an example of a piezoelectric thin film resonator, FIG. 1B is an XX cross-sectional view thereof, and FIG. 1C is an enlarged view of a portion surrounded by a dotted line in FIG. 1B. In these drawings, the piezoelectric thin film resonator 10 includes a substrate 11, a vibration space 20 formed by removing a part of the insulator layers 12 and 13 and the insulator layer 12 formed on the upper surface of the substrate 11. The piezoelectric laminated structure 14 is formed so as to straddle the substrate. The piezoelectric laminated structure 14 includes a lower electrode 15 formed on the upper surface of the insulating layer 13, a piezoelectric thin film 16 formed on the upper surface of the insulating layer 13 so as to cover a part of the lower electrode 15, and the piezoelectric thin film 16 The upper electrode 17 is formed on the upper surface of the piezoelectric thin film 16. On the substrate 11, a cavity 20 forming a vibration space is formed. A part of the insulator layer 13 is exposed toward the vibration space 20.

[0011] When the inclination angle of the outer periphery of the lower electrode exceeds 45 degrees and becomes steep, abnormal growth (separated growth) of the piezoelectric thin film A1N occurs at the edge of the outer periphery of the lower electrode as shown in Fig. 1C. Deep crater-like defects 30 occur between the columnar A1N particles. This crater-like defect causes the destruction of the A1 N film and impairs the reliability of the piezoelectric thin film resonator.

[0012] Similarly, abnormal growth of A1N used as the upper insulator layer also occurs from the edge of the outer periphery of the upper electrode, whose inclination angle is almost 90 °, and deep crater-like defects between adjacent columnar A1N grains 31 Is produced.

FIG. 2A is a schematic plan view showing an example of another piezoelectric thin film resonator different from the above, and FIGS. 2B and 2C are an XX sectional view and a YY sectional view, respectively. In these drawings, members having the same functions as those in FIGS. 1A to 1C are given the same reference numerals.

In these drawings, a piezoelectric thin film resonator 10 includes a substrate 11, an insulator layer 13 formed on the upper surface of the substrate 11, and a piezoelectric laminated structure formed on the upper surface of the insulator layer 13. Has body 14. The piezoelectric laminated structure 14 includes a lower electrode 15 formed on the upper surface of the insulating layer 13, and a piezoelectric thin film 16 formed on the upper surface of the insulating layer 13 so as to cover a part of the lower electrode 15. And an upper electrode 17 formed on the upper surface of the piezoelectric thin film 16.

[0015] Since the inclination angle of the outer periphery of the lower electrode is a steepness close to 90 ° (vertical), abnormal growth of A1N occurs at the edge of the outer periphery of the lower electrode as shown in Fig. 2C. A1N grain Deep crater-like defects 30 occur between the children. This crater-like defect causes the destruction of the A1N film and impairs the reliability of the piezoelectric thin film resonator.

[0016] Patent Document 5 by Ruby et al. Discloses oxygen (O 2) and hexafluoride as etching gases.

2

The bottom electrode edge is tapered by dry etching using SF (SF) and tapered.

6

A method for controlling the angle to 60 ° or less is disclosed. According to the publication, by controlling the taper angle to 60 ° or less, it is possible to suppress the generation of voids and discontinuous boundaries in the vicinity of the edge (lower electrode end) of the A1N thin film deposited and grown on the taper angle. Have been. However, in this publication, the effect of reducing voids and discontinuous boundaries in the A1N thin film is as follows: Dielectric breakdown strength, Power handling capacity, and electrostatic: The improvement effect of Electrostatic discharge (ESD)) is just mentioned.

[0017] Similarly, Patent Document 6 by Ginsburg et al. Discloses a method in which a taper angle is controlled to 30 ° or less by providing an inclination at the end of the lower electrode by a dry etching method. According to the same report, it is described that by controlling the taper angle to 30 ° or less, the generation of cracks in the vicinity of the edge of the AIN thin film deposited and grown thereon can be suppressed. However, this publication only reports that the production yield of a die that becomes a piezoelectric thin film resonator is improved by 15 to 80% as an effect of reducing cracks in the A1N thin film.

As is apparent from the above-mentioned known literatures and the like, in the manufacture of a piezoelectric thin film resonator, a gentle slope is provided on the outer peripheral portion of the lower electrode, and crater-like defects are generated due to the separate growth of the piezoelectric thin film. It is important to prevent.

[0019] In the piezoelectric thin film resonator shown in Figs. 2A to 2C, the cross-sectional shape of the outer periphery of the lower electrode is changed to provide a gentle slope, and a crater shape is generated from the edge edge of the outer periphery of the electrode during A1N thin film growth. Figure 3 shows an example of preventing separate growth. By making the inclination angle Θ with respect to the lower surface of the upper surface at the outer peripheral portion of the lower electrode 15 to be 30 ° or less, crater-like separated growth is prevented. In the piezoelectric thin film resonators shown in FIGS. 2A to 2C and FIG. 3, the inclination angle of the upper electrode end is close to 90 °, and the outer periphery of the upper electrode is a membrane 21 above the vibration space 20. Extends beyond the outer perimeter of the insulation Thickness is supported by the substrate 11 through the body layer 13.

[0020] Patent Document 1: JP-A-60-142607

Patent Document 2: JP 2000-69594 A

Patent Document 3: JP-A-6-295181

Patent Document 4: Japanese Patent Laid-Open No. 2005-236337

Patent Document 5: US Patent Application Publication No. 20030141946

Patent Document 6: US Patent Application Publication No. 20040263287

Disclosure of the invention

Problems to be solved by the invention

[0021] So far, various studies have been conducted to apply the A1N thin film to FBAR, SMR, or SBAR. However, a piezoelectric thin film resonator and a piezoelectric thin film filter that still exhibit sufficient performance in the gigahertz band have not been obtained, and the acoustic quality factor (Q value) and insertion loss of the resonator have been improved. It is desired. To improve the acoustic quality factor (Q value), it is necessary to form a highly oriented and homogeneous A1N thin film. For this reason, a method has been adopted in which a gentle slope is provided on the outer periphery of the lower electrode formed on the substrate to prevent crater-like separation growth during the growth of the A1N thin film.

[0022] The provision of an inclination in the outer peripheral portion of the lower electrode while applying a force means that the vibration state of the elastic wave is slightly different between the central portion and the outer peripheral portion of the resonator. As a result, if the slope of the outer periphery of the lower electrode becomes excessively gentle, the horizontal distance of the slope becomes too long, and the acoustic quality factor (Q value) of the piezoelectric thin film resonator is significantly reduced. . In addition, many noises are generated near the resonance peak in the impedance characteristics. As described above, various effects are caused on the piezoelectric characteristics, which is not preferable. The same effect is observed for the slope of the outer periphery of the upper electrode.

[0023] Therefore, the present invention solves the above-mentioned characteristic problems associated with the provision of a slope on the outer periphery of the lower electrode or the upper electrode, thereby taking advantage of the features of the A1N thin film, To provide a piezoelectric thin film resonator with excellent acoustic quality factor (Q value) with a large coupling coefficient, and extremely high performance compared to the past in terms of characteristics such as insertion loss, and a piezoelectric thin film device using the same. Objective. Means for solving the problem

[0024] The present inventors have determined how the properties of the aluminum nitride thin film, which greatly affects the resonance characteristics of FBAR, SMR, or SBAR, are affected by the shape and material of the outer periphery of the lower electrode or the upper electrode. We studied earnestly about whether to receive. As a result, a side spacer made of a material different from that of the lower electrode or the upper electrode is provided adjacent to the outer peripheral portion of the lower electrode or the upper electrode, and the side spacer and the outer peripheral portion of the lower electrode or the upper electrode are provided. The aluminum nitride thin film formed between the lower electrode and the upper electrode can be locked with high crystallinity without crater-like separation growth, and the half width of the curve (FWHM) 2.0. It was found that a highly oriented c-axis oriented aluminum nitride thin film of less than 0 ° could be obtained, and the adverse effects on the piezoelectric characteristics due to the inclination of the outer periphery of the lower electrode or the upper electrode could be eliminated. Furthermore, by preparing the metal thin film that constitutes the lower electrode or the upper electrode so as to have a specific material, structure, and crystal phase, the rocking curve half-width (FWHM) is 0.8 to 1.6 °. Further, it was found that a c-axis oriented aluminum nitride thin film having excellent orientation and crystallinity can be obtained. By using such highly oriented and highly crystalline c-axis oriented aluminum nitride thin film, the acoustic quality factor (Q value) is large, the electromechanical coupling coefficient is large, the loss is low, and the performance is high. As a result, the present inventors have found that FBAR, SMR or SBAR can be realized.

[0025] According to the present invention, to achieve the above-described object,

A substrate having a vibration space or an acoustic reflection layer; and a piezoelectric multilayer structure disposed so as to face the vibration space or the acoustic reflection layer, the piezoelectric multilayer structure being close to the vibration space or the acoustic reflection layer. A piezoelectric thin film resonator having at least a lower electrode, a piezoelectric thin film and an upper electrode arranged in order of lateral force,

A side spacer having a different material from that of the electrode is disposed around an outer peripheral portion of at least one of the lower electrode and the upper electrode, and a step at an interface between the side spacer and the electrode. A piezoelectric thin film resonator is provided, characterized in that is less than 25 nm.

In one embodiment of the present invention, the piezoelectric thin film is made of aluminum nitride (A1N). In one aspect of the present invention, the piezoelectric thin film having the aluminum nitride force also has a (0002) diffraction peak rocking 'curve half width (FWHM) of 0.8 to 1.6 °.

[0027] In one embodiment of the present invention, the step at the interface between the side spacer and the electrode is less than 3 nm. In one aspect of the present invention, the side spacer 1 has an upper surface formed in a slope shape with respect to the lower surface. In one aspect of the present invention, the side spacer has an upper surface tilt angle of 3 to 45 degrees with respect to the lower surface. According to one aspect of the present invention, the acoustic impedance of the side spacer is larger than the acoustic impedance of the electrode.

[0028] In one aspect of the present invention, the side spacer 1 also has an insulator strength. In one embodiment of the present invention, the side spacer is made of silicon dioxide)), silicon nitride (Si

2

N), silicon oxynitride (Si ON), aluminum nitride (A1N), aluminum oxynitride (AIO

twenty two

N), aluminum oxide (Al 2 O 3), zirconium oxide (ZrO 2), and tantalum oxide (Ta y 2 3 2 2 0) force group power It is an insulator power mainly composed of at least one selected material.

Five

In one embodiment of the present invention, the side spacer 1 also has a conductor force. In one aspect of the present invention, the side spacer is made of a conductor whose main component is at least one material selected from a group force including tungsten (W), tungsten silicide (WSi), and iridium (Ir) forces. .

[0030] In one embodiment of the present invention, at least one of the upper electrode and the lower electrode is also a molybdenum denka. In one embodiment of the present invention, at least one of the upper electrode and the lower electrode is one selected from the group consisting of molybdenum, ruthenium, aluminum, iridium, cobalt, nickel, platinum, and copper metal. It is comprised by the laminated body of.

In one embodiment of the present invention, the lower electrode is a laminate of a lower metal layer having a thickness dl and an upper metal layer having a thickness d2, and dlZd2> l and 150 nm <(dl + d2) <450 nm. In one embodiment of the present invention, the upper electrode is a laminate of a lower metal layer having a thickness of d3 and an upper metal layer having a thickness of d4, d4Zd3> l and 150 nm <(d3 + d4) < 45 Onm.

[0032] In one aspect of the present invention, the vibration region defined as a region where the lower electrode and the upper electrode overlap each other when viewed in the thickness direction of the piezoelectric multilayer structure is the vibration space. Or it is located inside the outer periphery of the acoustic reflection layer. In one aspect of the present invention, the distance w between the end of the vibration region and the outer periphery of the vibration space or the sound reflection layer, as viewed in the thickness direction of the piezoelectric multilayer structure, and the vibration region Total t force between the thickness of the piezoelectric laminated structure and the thickness of the insulating layer. The relational expression 0 <wZt≤2 is satisfied.

In one aspect of the present invention, an insulating layer is attached to the upper surface or the lower surface of the piezoelectric multilayer structure. In one aspect of the present invention, the insulating layer is formed in contact with the lower surface of the lower electrode. In one aspect of the present invention, the insulating layer is formed in contact with the upper surface of the upper electrode. In one embodiment of the present invention, the insulating layer includes aluminum nitride (A1N), aluminum oxynitride (AIO N), aluminum oxide (Al 2 O 3), nitrogen nitride.

2 3 Silicon (SiN), Oxynitride (Si ON), Zirconium Oxide (ZrO) and Titanium Oxide

2 2 2

Group power consisting of Ta (O), which is composed mainly of at least one selected material.

twenty five

is there.

In one embodiment of the present invention, the thickness of the lower insulating layer formed in contact with the lower surface of the lower electrode is d5 force S25 to 300 nm. In one embodiment of the present invention, the thickness d6 of the upper insulating layer formed in contact with the upper surface of the upper electrode is 40 to 600 nm. In one embodiment of the present invention, the ratio d6Zd5 between the thickness d6 of the insulating portion and the thickness d5 of the lower insulating layer satisfies the relation 1≤d6 / d5 <4.

Furthermore, in an aspect of the present invention, the piezoelectric thin film resonator has an acoustic quality factor (Q value) of an anti-resonance peak in an impedance curve of 1000 or more.

[0036] Further, according to the present invention, there is provided a piezoelectric thin film device configured by combining a plurality of the above-described piezoelectric thin film resonators. The piezoelectric thin film resonator includes a stacked piezoelectric thin film resonator. Examples of the piezoelectric thin film device include, but are not limited to, a VCO (voltage controlled oscillator), a filter, and a transmission / reception switch configured using the piezoelectric thin film resonator and the laminated piezoelectric thin film resonator as described above. It ’s not something. In such a piezoelectric thin film device, the characteristics at a high frequency of 1 GHz or more can be remarkably improved.

[0037] Further, according to the present invention, the above-mentioned object is achieved as follows:

A method of manufacturing the above piezoelectric thin film resonator,

A first step of forming a lower insulating layer on the substrate; A second step of forming the lower electrode on the lower insulating layer;

After an insulator or conductor having a different material from that of the lower electrode is deposited on the exposed surfaces of the lower electrode and the lower insulating layer, the upper surface of the lower electrode is exposed by etch back, and the periphery of the outer periphery of the lower electrode Forming a side spacer for the lower electrode in a third step;

A fourth step of forming a piezoelectric material layer on the exposed surfaces of the lower electrode, the lower electrode side spacer and the lower insulating layer;

A fifth step of forming the upper electrode on the piezoelectric material layer;

A piezoelectric process comprising: a sixth step of forming the piezoelectric thin film by patterning the piezoelectric material layer; and a seventh step of forming an upper insulating layer on the piezoelectric thin film and the upper electrode. Manufacturing method of thin film resonator,

Is provided.

[0038] In one embodiment of the present invention, an insulator or a conductive material having a material different from that of the upper electrode is formed on the exposed surfaces of the upper electrode and the piezoelectric material layer between the fifth step and the sixth step. After the body is deposited, the upper surface of the upper electrode is exposed by etch back, and the step of forming the side spacer for the upper electrode is provided around the outer periphery of the upper electrode.

[0039] Furthermore, according to the present invention, the above-mentioned object is achieved as follows:

A method of manufacturing the above piezoelectric thin film resonator,

A first step of forming a lower insulating layer on the substrate;

A second step of forming the lower electrode on the lower insulating layer so that the end thereof has a slope shape;

A third step of forming a piezoelectric material layer on the exposed surfaces of the lower electrode and the lower insulating layer; a fourth step of forming the upper electrode on the piezoelectric material layer;

A fifth step of patterning the piezoelectric material layer to form the piezoelectric thin film; and depositing an insulator or conductor having a different material from the upper electrode on the exposed surfaces of the upper electrode and the piezoelectric thin film; The upper surface of the upper electrode is exposed by etch back, and the side spacer for the upper electrode is formed around the outer periphery of the upper electrode. 6 processes,

A method of manufacturing a piezoelectric thin film resonator, comprising: a seventh step of forming an upper insulating layer on the piezoelectric thin film and the upper electrode;

Is provided.

The invention's effect

[0040] In a piezoelectric thin film resonator having at least a lower electrode, a piezoelectric thin film, and an upper electrode disposed on a substrate, a side surface made of a material different from that of the lower electrode and the upper electrode is formed on the outer periphery of at least one of the lower electrode and the upper electrode. A spacer is provided, and an aluminum nitride thin film is formed between the upper and lower electrodes produced by controlling the caking method so that the step at the interface between the side spacer and the electrode is less than 25 nm. As a result, a highly oriented and highly crystalline c-axis oriented aluminum nitride thin film with no crater separation and growth can be obtained. Furthermore, by preparing the metal thin film constituting the electrode to have a specific material, structure or crystal phase, the rocking curve half-width (FWHM) of the (0002) diffraction peak is 2.0 ° or less, Preferably, a highly oriented and highly crystalline c-axis oriented aluminum nitride thin film of 0.8 to 1.6 ° can be formed.

Here, the side spacer is formed around the electrode in contact with the side wall of the outer periphery of the electrode.

[0042] By providing the side spacer, the adverse effect on the piezoelectric characteristics caused by the inclination of the lower electrode or the upper electrode end, which has been a problem with conventional piezoelectric thin film resonators, can be eliminated. coupling coefficient k ² and the piezoelectric thin-film resonator of excellent performance and high reliability in the acoustic quality factor (Q value) can be provided. Therefore, the piezoelectric thin film devices such as VCO (Voltage Controlled Oscillator), filter, and duplexer configured using the same can remarkably improve the characteristics at a frequency higher than 1 GHz.

Brief Description of Drawings

FIG. 1A is a schematic plan view showing an example of a piezoelectric thin film resonator.

1B is a cross-sectional view taken along the line XX in FIG. 1A.

FIG. 1C is an enlarged view of a portion surrounded by a dotted line in FIG. 1B.

FIG. 2A is a schematic plan view showing an example of a piezoelectric thin film resonator. 2B is a cross-sectional view taken along the line XX in FIG. 2A.

FIG. 2C is a Y-Y sectional view of FIG. 2A.

FIG. 3 is a cross-sectional view showing an example in which a gentle slope is provided by changing the cross-sectional shape of the outer periphery of the lower electrode in the piezoelectric thin film resonator of FIGS. 2A to 2C.

FIG. 4A is a schematic plan view showing an embodiment of a piezoelectric thin film resonator according to the present invention.

4B is a cross-sectional view taken along the line XX in FIG. 4A.

FIG. 4C is an enlarged view of a portion surrounded by a dotted line in FIG. 4B.

FIG. 5A is a schematic cross-sectional view for explaining a step of forming a side spacer around the side wall of the lower electrode.

FIG. 5B is a schematic cross-sectional view for explaining a step of forming a side spacer around the side wall of the lower electrode.

FIG. 6A is a schematic cross-sectional view for explaining a step of forming a side spacer around the side wall of the lower electrode.

FIG. 6B is a schematic cross-sectional view for explaining a step of forming a side spacer around the side wall of the lower electrode.

FIG. 7A is a schematic plan view showing an embodiment of a piezoelectric thin film resonator according to the present invention.

FIG. 7B is a cross-sectional view taken along the line XX in FIG. 7A.

FIG. 7C is a sectional view taken along the line Y—Y in FIG. 7A.

FIG. 7D is an enlarged view of a portion surrounded by a dotted line in FIG. 7C.

FIG. 8A is a schematic plan view showing an embodiment of a multilayer piezoelectric thin film resonator according to the present invention. FIG. 8B is an XX cross-sectional view of FIG. 8A.

FIG. 9 is a schematic plan view of a thin film piezoelectric filter as an embodiment of the piezoelectric thin film device of the present invention.

Explanation of symbols

10 Piezoelectric thin film resonator

11 Substrate made of single crystal or polycrystal

12 Board insulation layer 13 Lower insulator layer (lower insulator layer)

14 Piezoelectric laminated structure

15 Bottom electrode

15a Lower electrode body

15b Lower electrode terminal

16, 16- 1, 16- 2 Piezoelectric thin film (piezoelectric thin film)

17 Upper electrode

17a Upper electrode body

17b Upper electrode terminal

17 'internal electrode

18 Upper electrode in multilayer piezoelectric thin film resonator

18a Main part of upper electrode in multilayer piezoelectric thin film resonator

18b Terminal part of the upper electrode in the stacked piezoelectric thin film resonator

19 Via Honoré for etching

20 Vibration space formed on the substrate by etching

21 Membrane located above the vibration space

23 Upper insulator layer (upper insulating layer)

25 Thin films deposited to form side spacers

26 Side spacer formed adjacent to the outer periphery of the electrode

BEST MODE FOR CARRYING OUT THE INVENTION

[0045] Hereinafter, embodiments of the present invention will be described in detail.

FIG. 4A is a schematic plan view showing an embodiment of a piezoelectric thin film resonator according to the present invention, and FIG. 4B is an XX cross-sectional view thereof. FIG. 4C is an enlarged view of a portion surrounded by a dotted line in FIG. 4B. In these drawings, the piezoelectric thin film resonator 10 includes a substrate 11, an insulating layer 12 formed on the upper surface of the substrate 11, a lower insulating layer 13, and a cavity formed by removing a part of the insulating layer 12. The piezoelectric laminated structure 14 is formed so as to straddle the vibration space 20. In addition, it can be considered that the board | substrate said by this invention is comprised by the member which consists of the board | substrate 11 and the insulating layer 12. FIG. In this sense, the insulating layer 12 is referred to as a substrate insulating layer. In the present invention A vibration space 20 is formed on the substrate. The piezoelectric laminated structure 14 includes a lower electrode 15 formed on the upper surface of the lower insulating layer 13, and a piezoelectric thin film 16 formed on the upper surface of the lower insulating layer 13 so as to cover a part of the lower electrode 15. And an upper electrode 17 formed on the upper surface of the piezoelectric thin film 16. A part of the lower insulating layer 13 is exposed toward the vibration space 20. An exposed portion of the lower insulating layer 13 and a partial membrane (vibration membrane) 21 of the piezoelectric multilayer structure 14 corresponding thereto are configured. In addition, as described above, the force that the lower insulating layer 13 is interposed between the piezoelectric multilayer structure 14 and the vibration space 20, including such a form, the piezoelectric multilayer structure 14 faces the vibration space 20. Suppose you are. The lower electrode 15 and the upper electrode 17 are formed of main portions 15a and 17a formed in a region corresponding to the membrane 21, and terminal portions 15b for connecting the main portions 15a and 17a to an external circuit. 17b. The terminal portions 15b and 17b are located outside the region corresponding to the membrane 21.

As the substrate 11, a single crystal such as Si (100) single crystal or a substrate in which a polycrystalline film such as silicon, diamond or the like is formed on the surface of a base material such as Si single crystal can be used. As the substrate 11, it is possible to use other semiconductors or those having insulating strength. The specific resistance value of the substrate 11 is, for example, 3 kQ′cm or more, preferably 5 kQ′cm or more, and more preferably 7 kΩ′cm or more. As a method of forming the vibration space 20, via holes 19 penetrating each layer of the piezoelectric multilayer structure and the lower insulating layer 13 are opened, and an etching solution such as a hydrofluoric acid aqueous solution is injected from the via holes 19 to form the substrate insulating layer 12. A method of removing a part of the lower region of the piezoelectric multilayer structure including a part by wet etching is included. As will be described later, the vibration space may be formed by deep etching (Deep RIE) of the lower surface side of the substrate 11. The vibration space may be any shape of cavity or recess as long as it allows vibration of the membrane 21. Furthermore, instead of forming the vibration space as described above to form an air gap type piezoelectric thin film resonator, an acoustic reflection layer (by alternately laminating high acoustic impedance material layers and low high acoustic impedance material layers) It is also possible to form an acoustic mirror type piezoelectric thin film resonator by forming an acoustic Bragg reflector. When the substrate 11 having silicon power is used, a silicon oxide film formed by thermal oxidation of the surface of the substrate 11 can be used as the substrate insulating layer 12. [0048] The lower insulating layer 13 preferably has a high elastic modulus and material strength. As the lower insulating layer 13, for example, a dielectric film mainly composed of silicon nitride (SiN), a silicon oxynitride (Si

2

ON) as a main component, dielectric film mainly composed of aluminum nitride (A1N),

2

Dielectric film mainly composed of aluminum oxynitride (AIO N), dielectric film mainly composed of aluminum oxide (Al 2 O 3) y 2 3, dielectric film mainly composed of zirconium oxide (ZrO 2), Acid

2

Dielectric films composed mainly of tantalum (Ta 2 O 3) and these dielectric films are stacked

twenty five

A laminated film can be used. Regarding the material of the lower insulating layer 13, the main component refers to a component whose content in the dielectric film is 50 equivalent% or more. The dielectric film may be a single layer or a laminate. Furthermore, it may be a multi-layer force with a layer attached to improve adhesion.

[0049] Examples of the method of forming the lower insulating layer 13 include a sputtering method, a vacuum deposition method, and a CVD method. In the present invention, the lower insulating layer 13 in the region corresponding to the membrane 21 is entirely removed by etching, and the lower electrode 15 is exposed toward the vibration space 20 (that is, the membrane removes the lower insulating layer 13). A piezoelectric thin film resonator having a structure) may also be employed. Thus, removing all of the insulating layer 13 in the region corresponding to the membrane 21 has an advantage of improving the electromechanical coupling coefficient although the temperature characteristic of the resonance frequency is slightly deteriorated.

[0050] The lower electrode 15 includes, for example, a metal thin film mainly composed of molybdenum (Mo), a metal thin film mainly composed of ruthenium (Ru), a metal thin film mainly composed of aluminum (A1), and an iridium (Ir ) Metal thin film, cobalt (Co) metal thin film, nickel (I r) metal thin film, platinum (Pt) metal thin film, copper (Cu) At least one metal thin film selected from metal thin films containing as a main component, a metal thin film containing molybdenum as a main component, and a group force consisting of ruthenium, aluminum, iridium, cobalt, nickel, platinum and copper power at least one selected It consists of a stack of metal thin films composed mainly of various metals. Here, for example, a metal thin film mainly composed of molybdenum means that 90% or more of molybdenum is contained. The lower electrode 15 may be formed by stacking an adhesion metal layer (adhesion layer) formed between the metal thin film and the lower insulating layer 13 as necessary. The part of the lower electrode other than the adhesive metal layer is called the lower electrode main layer. Yeah. Lower electrode 15 Thickness ί, 150-450mn force! / ヽ.

In the present invention, as the lower electrode 15, a metal thin film having a thickness d2 (second metal layer: upper metal layer) and a metal thin film having a thickness dl (first metal layer: lower metal layer) Can be used. As the upper metal layer or the lower metal layer, a metal thin film mainly composed of molybdenum, or a metal mainly composed of one kind of metal selected from the group consisting of ruthenium, aluminum, iridium, cobalt, nickel, platinum, or copper. A thin film can be exemplified. Here, when an adhesion layer is provided between the lower metal layer and the lower insulating layer 13, the thickness dl is a value including the thickness of the adhesion layer. As the relationship between the thickness d2 of the upper metal layer and the thickness dl of the lower metal layer, it is preferable to adopt a film thickness configuration in which d lZd2> l and 150 nm (dl + d2) and 450 nm. In particular, this is because a highly oriented upper metal layer (for example, a metal thin film mainly composed of molybdenum) having a high acoustic impedance between the lower metal layer (for example, a metal thin film mainly composed of aluminum) and the piezoelectric thin film. ) Is preferable. As a result, the electrode loss [insertion loss] (IL) and acoustic quality factor (Q value) of the obtained piezoelectric thin film resonator can be improved. In particular, the acoustic quality factor (Q value) of the anti-resonance peak in the impedance characteristic has been improved, and the roll-off characteristics on the high band side of the pass band of the piezoelectric thin film filter produced by combining multiple piezoelectric thin film resonators have been improved. To do.

The piezoelectric thin film 16 is preferably made of aluminum nitride (A1N), and its thickness is, for example, 0.5 to 3. O / z m. When using at a frequency of about 1 GHz, increase the film thickness. When using at a high frequency around 5 GHz, decrease the film thickness.

Similar to the lower electrode 15, the upper electrode 17 mainly includes a metal thin film mainly composed of ruthenium, a metal thin film mainly composed of aluminum, and iridium in addition to a metal thin film mainly composed of molybdenum. At least one metal thin film selected from a metal thin film containing cobalt, a metal thin film containing cobalt as a main component, a metal thin film containing nickel as a main component, a metal thin film containing platinum as a main component, and a metal thin film containing copper as a main component And a laminate of a metal thin film mainly composed of molybdenum and a metal thin film composed mainly of at least one metal selected from the group consisting of ruthenium, aluminum, iridium, cobalt, nickel, platinum and copper. I can do it. Further, the upper electrode 17 may be formed by laminating an adhesion metal layer (adhesion layer) formed between the metal thin film and the piezoelectric thin film 16 as described above. Adhesive metal layer or higher The part of the outer upper electrode is called the upper electrode main layer. The thickness of the upper electrode 17 is preferably 150 to 450 nm.

In the present invention, the upper electrode 17 includes a metal thin film having a thickness d3 (third metal layer: lower metal layer) and a metal thin film having a thickness d4 (fourth metal layer: upper metal layer). It is possible to use a laminated body. As the lower metal layer or the upper metal layer, a metal thin film mainly composed of molybdenum, or a metal mainly composed of one kind of metal selected from the group consisting of ruthenium, aluminum, iridium, cobalt, nickel, platinum or copper. A thin film can be exemplified. Here, when an adhesion layer is provided between the lower metal layer and the piezoelectric thin film 16, the thickness d3 is a value including the thickness of the adhesion layer. In addition, when the adhesion layer is attached to the upper metal layer, the thickness d4 is a value including the thickness of the adhesion layer. As the relationship between the thickness d3 of the lower metal layer and the thickness d4 of the upper metal layer, it is preferable to adopt a film thickness configuration in which d4Zd3> l is 150 nm (d3 + d4) and 450 nm. This is particularly because the lower metal layer (for example, a metal thin film mainly composed of molybdenum) having high acoustic impedance and high orientation between the upper metal layer (for example, a metal thin film mainly composed of aluminum) and the piezoelectric thin film. It is preferable when intervening. As a result, the electrode loss [insertion loss] (IL) and acoustic quality factor (Q value) of the obtained piezoelectric thin film resonator can be improved. In particular, the acoustic quality factor (Q value) of the anti-resonance peak in the impedance characteristics has been improved, and the roll-off characteristics on the high band side of the pass band of the piezoelectric thin film filter produced by combining multiple piezoelectric thin film resonators have been improved. To do.

In the present invention, if necessary, an aluminum nitride (A1N), an aluminum oxynitride (AIO N), an aluminum oxide (Al 2 O 3), a silicon nitride (SiN), an acid, or the like is formed on the upper electrode 17 as necessary. y 2 3

Made of silicon nitride (Si ON;), zirconium oxide (ZrO) and tantalum oxide (Ta 2 O 3).

An upper insulating layer 23 composed mainly of at least one kind of material is laminated, in which a group force of 2 2 2 2 5 is also selected. In this case, the membrane 21 is constituted by an exposed portion of the lower insulating layer 13 and portions of the piezoelectric multilayer structure 14 and the upper electrode layer 23 corresponding thereto.

[0056] In the piezoelectric thin film resonator having the configuration shown in these drawings, the inventors have the resonance characteristics such as the material, shape and crystallinity of the lower electrode, or the orientation and crystallinity of the A1N thin film. We examined how it depends on the properties!

In the present invention, the piezoelectric laminated structure 14 includes the lower electrode 15 and the upper electrode 17. The side spacer 26 is formed around the outer periphery of at least one of the electrodes and is made of a material different from that of the electrode. The side spacer 26 is made of an insulator or a conductor and is formed in a slope shape. In addition, the insulator or conductor used for the side spacers 26 is preferably made of a material other than resin, preferably having a bulk density of 1.6 gZcm ³ or more.

[0058] As a method of forming the side spacer 26 made of the insulator or conductor as described above, a gate electrode of a MOS (Metal—Oxide—Semiconductor) type transistor, a gate insulating film (gate oxide) Sidewall spacer technology that is generally applied to the formation of side walls of the film can be employed. The outline of the method of forming a side spacer made of an insulator around the outer periphery of the electrode by the side wall spacer technique is as follows.

FIG. 5A and FIG. 5B are schematic cross-sectional views for explaining a process of forming a side spacer around the outer peripheral portion (side wall) of the lower electrode. In forming the side spacers, first, as shown in FIG. 5A, the entire surface of the lower insulating layer 13 is covered by a low-pressure CVD method so as to cover the patterned lower electrode 15 (see FIG. 5A). SiO) (LP—TEOS) force

2

An insulating film 25 is deposited to a thickness of 300 to 900 nm. Other methods of insulating film formation include SiN (LP—SiN) film formation by low pressure CVD method, BPSG (Boron Phosphor Silicate Glass) film formation by low pressure CVD method, and LP—TEOS film on LP—SiN film. An example of this is the formation of a SiO 2 / SiN multilayer film in which layers are stacked.

2

Thereafter, as shown in FIG. 5B, the upper surface of the lower electrode 15 is exposed by an anisotropic dry etching method using ICP plasma so that the upper surface and the surface of the SiO film are smoothly connected. Na

2

Etch back until the SiO2 film is left only around the side wall of the lower electrode 15.

2

The side spacer 26 is formed. In order to make the inclination angle of the side spacer 26 gentle, anisotropic dry etching and surface polishing (CMP) can be used in combination.

FIG. 6A and FIG. 6B are also schematic cross-sectional views for explaining the process of forming the side spacer around the side wall of the lower electrode. In the formation of the side spacer, first, as shown in FIG. 6A, tungsten (W) (by a low temperature CVD method is applied to the entire surface of the lower insulating layer 13 so as to cover the patterned lower electrode 15. LT-W) conductive film 25 300 Deposit to a thickness of ~ 900nm. As another method for forming a conductive film, a monosilane-based WSi (LT-WSi) film can be formed by a low temperature CVD method.

[0062] After that, as shown in FIG. 6B, the upper surface of the lower electrode 15 is exposed by using an anisotropic dry etching method or surface polishing method (CMP) using ECR plasma and a dry etching method in combination. Etch back until the upper surface and the surface of the SiO film are connected smoothly.

2

As a result, the side spacer 26 is formed leaving the W film only around the side wall of the lower electrode 15.

[0063] What is important in the formation of the side spacer is that the etch back conditions are set so that the step at the interface between the electrode and the side spacer is less than 25 nm, preferably less than 10 nm, more preferably less than 3 nm. Is to control. When the level difference between the two is 25 nm or more, abnormal growth of A1N due to the level difference is likely to occur, and deep crater-like defects may occur between adjacent columnar AIN grains. This crater is not preferable because it causes damage to the A1N film and impairs its reliability as a piezoelectric thin film resonator.

[0064] The thickness d5 of the lower insulating layer 13 formed in contact with the lower surface of the lower electrode is 25 to 300 nm, preferably 30 to 200 nm. When the thickness of the lower insulating layer 13 is less than 25 nm, the crystal orientation of the metal thin film mainly composed of molybdenum, ruthenium, aluminum, iridium, cobalt, nickel, platinum, copper, etc. deposited thereon is poor. The rocking 'curve half-value width of the corresponding X-ray diffraction peak tends to widen. The broadening of the rocking 'curve half-width of the metal thin film that serves as the lower electrode brings about a decrease in the crystal orientation of the A1N thin film deposited on the upper surface. If the thickness of the lower insulating layer 13 exceeds 300 nm, the electromechanical coupling coefficient of the obtained piezoelectric thin film resonator tends to decrease, and the piezoelectric characteristics tend to deteriorate.

[0065] The thickness d6 of the upper insulating layer 23 formed in contact with the upper surface of the upper electrode is preferably 40 to 600 nm. Furthermore, the ratio between the thickness d5 of the lower insulating layer 13 formed in contact with the lower surface of the lower electrode and the thickness d6 of the upper insulating layer 23 formed in contact with the upper surface of the upper electrode d6 Zd5 force l≤d6Zd5≤4 It is preferable to control the thickness d5 and the thickness d6 so as to satisfy the relationship. [0066] By forming the upper insulating layer 23 in contact with the upper surface of the upper electrode, spurious near the resonance peak of the obtained piezoelectric thin film resonator is reduced. In particular, when the relationship of d6Zd5 force l≤d6 Zd5≤4 is satisfied, the spurious reduction effect is large. When the thickness d6 of the upper insulating layer 23 is less than 40 nm, the spurious suppression effect tends to be remarkably reduced. Conversely, when the thickness d6 of the upper insulating layer 23 exceeds 600 nm, the piezoelectric characteristics such as the electromechanical coupling coefficient and the acoustic quality factor (Q value) of the obtained piezoelectric thin film resonator tend to be poor. Further, the upper insulating layer 23 is made of a chemically stable material, and there is an effect that the environmental resistance of the obtained piezoelectric thin film resonator is improved. In order to enhance the spurious reduction effect and the environmental resistance improvement effect as described above, it is important to improve the crystal orientation of the upper insulating layer 23 formed in contact with the upper surface of the upper electrode. In the present invention, by controlling the rocking 'curve half-value width of the metal thin film such as molybdenum constituting the upper electrode 17 to be 3 ° or less, a highly oriented upper insulating layer is formed and good spurious Reduction effect and excellent environmental resistance can be realized.

[0067] The vibration space 20 can be formed as follows. That is, after forming the substrate insulating layer 12 on the upper surface of the substrate 11, a pattern-like sacrificial layer is formed on the vibration space forming region of the substrate insulating layer 12. A lower insulating layer 13 and a piezoelectric laminated structure 14 (and an upper insulating layer 23) are formed thereon. Via hole 19 is formed by deep etching (Deep RIE (Reactive Ion Etching)) from the upper side of the figure (upper insulating layer 23 and) through the layers constituting piezoelectric laminated structure 14 and insulating layer 13 to form a sacrificial layer. An etching solution is injected from the via hole 19 to remove the sacrificial layer and the substrate insulating layer 12 in the vibration space forming region, thereby forming a vibration space 20 that is a cavity. A thin film laminated on the vibration space 20 constitutes the membrane 21. In this piezoelectric thin film resonator, the A1N thin film 16 on the vibration space 20, the lower electrode 15 and the upper electrode 17 sandwiching the A1N thin film constitute a piezoelectric laminated structure 14, and as described above, the piezoelectric laminated structure 14 At least one of them is aluminum nitride (A1N), aluminum oxynitride (AIO N), aluminum oxide (Al 2 O 3), silicon nitride (SiN), silicon oxynitride (Si ON), zirconium oxide

2 3 2 2

The main component is at least one material selected from (ZrO) and tantalum oxide (TaO).

2 2 5

Insulating layers 13 and 23 exist. [0068] Molybdenum (Mo), ruthenium (Ru), aluminum (A1), iridium (Ir), cobalt (Co), nickel (Ni), platinum (Pt) and copper used for the lower electrode 15 and the upper electrode 17 Examples of the method for forming a metal thin film containing as a main component at least one metal selected from the group consisting of (Cu) include a sputtering method and a vacuum evaporation method.

[0069] A thin film containing these metals as a main component can usually be easily formed by a DC magnetron sputtering method or an RF magnetron sputtering method. However, when using vacuum deposition, the melting point of molybdenum (Mo), ruthenium (Ru) and iridium (Ir) is high! / Because of its high melting point (melting point of ruthenium 2310 ° C). The melting point of molybdenum is 2620 ° C, the melting point of tungsten is 3410 ° C), and it is difficult to produce a thin film by resistance heating evaporation, so it is necessary to use electron beam evaporation. As for the crystal phase, ruthenium is known to be hexagonal, and molybdenum, aluminum, iridium, conoleto, nickel, platinum and copper are known to be cubic. When thin films of these metal crystal phases are formed by conventional technology, highly oriented metal crystal films with a rocking curve half-width (FWHM) of the X-ray diffraction peak of 3.0 ° or less are deposited. It was difficult to do.

In the present invention, paying attention to the material, thickness and crystal orientation of the lower electrode, the correlation with the crystal orientation of the aluminum nitride thin film formed on the metal thin film was examined in detail. As a result, the thickness and the microstructure of the insulating film serving as a base layer (crystal orientation, surface roughness) both by controlling the ultra-high vacuum sputtering apparatus (ultimate vacuum: 10 ^_6 Pa or less, preferably 4xl0_ ⁷ Pa ) And optimized film formation conditions such as film formation pressure, film formation temperature, DC output or RF output, making it possible to deposit highly oriented metal crystal films. In addition, it is possible to improve the crystal orientation by performing pretreatment such as heat treatment before film formation or soft etching.

[0071] Furthermore, the present inventors controlled the deposition conditions of the metal thin film used as the lower electrode 15 to improve the crystal orientation, and then nitrided the metal thin film or the metal thin film laminate. By forming an aluminum thin film, a highly oriented and highly crystalline c-axis oriented aluminum nitride thin film with a rocking 'curve half-width (FWHM) of (0002) diffraction peak of 0.8 to 1.6 ° is obtained. I found out that By using highly oriented and highly crystalline c-axis oriented aluminum nitride thin film, low loss and excellent bandwidth and frequency temperature characteristics High performance FBAR, SMR or SBAR can be realized.

[0072] The lower electrode 15 is formed by forming a metal thin film mainly composed of at least one metal selected from the group consisting of an adhesion metal layer deposited as necessary and the above-mentioned various metals in this order. It is formed by patterning these metal thin films into a predetermined shape using a lithography technique. The A1N thin film 16 can be formed on the upper surface of the lower insulating layer 13 on which the lower electrode 15 is formed by reactive sputtering. The upper electrode 17 is formed by forming a metal thin film mainly composed of at least one metal selected from the group consisting of the various metals described above, and then using the photolithography technique in the same manner as the lower electrode 15. Is formed into a predetermined shape (for example, a shape close to a circle). After the upper electrode is bumped, the A1N thin film 16 is patterned into a predetermined shape by etching away a portion of the A1N thin film 16 except for the portion on the vibration space 20 by using a photolithography technique.

[0073] When the inclination angle of the end portion of the lower electrode 15 becomes steep, abnormal A1N growth occurs at the edge portion of the lower electrode end portion as shown in FIG. 2C, and a deep crater shape is formed between adjacent columnar A1N grains. Cause defects. This crater causes the destruction of the A1N film and impairs the reliability of the piezoelectric thin film resonator. For this reason, as shown in FIG. 3, it is necessary to prevent crater-like separation growth by making the inclination of the surface of the lower electrode end portion where the metal thin film and the aluminum nitride thin film contact with the substrate gentle. However, if the tilt angle of the lower electrode end becomes gradual, the horizontal distance of the tilted portion becomes too long, and the acoustic quality factor (Q value) of the piezoelectric thin film resonator decreases, resulting in impedance characteristics. When a lot of noise is generated near the resonance peak, there is a problem.

[0074] As shown in FIG. 4B and FIG. 4C, the present inventors provide a side spacer 26 made of a material different from the electrode around the outer periphery of the lower electrode 15 or the upper electrode 17. The side spacer 26 is formed in a slope shape, and the upper and lower electrodes of the upper and lower electrodes are manufactured by controlling the shielding method so that the step difference at the interface between the electrode and the side spacer 26 is less than 25 nm. By forming an aluminum nitride thin film between them, a highly oriented and highly crystalline c-axis oriented aluminum nitride thin film with no crater-like separation growth is obtained, which is caused by the inclination of the edge of the lower electrode or the upper electrode. The ability to eliminate adverse effects on piezoelectric properties I found it.

[0075] The side spacer 26 is formed of an insulator or a conductor. Side spacers 26 made of an insulator, such as silicon dioxide)), silicon nitride (SiN), oxynitride

2

Silicon (Si ON), aluminum nitride (A1N), aluminum oxynitride (AIO N), oxide

2 2 y Made of ruminium (Al 2 O 3), zirconium oxide (ZrO 2) and tantalum oxide (Ta 2 O 3)

2 3 2 2 5 Can be formed of an insulator mainly composed of at least one material selected from the group

[0076] The side spacer 26 also having a conductor force is formed of a conductor mainly composed of at least one material selected from the group force of tungsten (W), tungsten silicide (WSi), and iridium (Ir) forces. can do.

[0077] The side spacer 26 made of an insulator or a conductor is formed in a slope shape, and the inclination angle with respect to the lower surface of the upper surface of the slope is preferably 3 to 45 °. When the inclination angle is smaller than 3 °, the slope length becomes too long, and it becomes difficult to ensure the dimensional accuracy in the plane direction of each layer constituting the piezoelectric thin film resonator. Piezoelectric properties such as coupling coefficient and acoustic quality factor (Q value) tend to deteriorate. When the inclination angle exceeds 45 °, crater-like separation growth of the aluminum nitride thin film tends to occur from the boundary between the electrode and the side spacer 26 or the outer edge of the side spacer 26.

[0078] Regarding the shape of the electrode end portion in contact with the side spacer 126, it is preferable that the inclination angle of the electrode side wall surface with respect to the lower surface of the electrode is 70 to 90 ° (that is, substantially vertical). By setting the tilt angle to 70 to 90 °, the acoustic quality factor (Q value) of the obtained piezoelectric thin film resonator is improved, and it has excellent characteristics such as insertion loss, roll-off steepness and cutoff characteristics. A high performance piezoelectric thin film resonator can be manufactured.

That is, the piezoelectric thin film resonator of the present invention is a resonator as described above, and is a vibration space or a semiconductor having an acoustic reflection layer. A substrate made of an insulator and a vibration space of the substrate. Or a piezoelectric thin film resonator having at least a lower electrode, an aluminum nitride piezoelectric thin film, and an upper electrode arranged in order at a position facing the acoustic reflection layer, wherein at least one of the lower electrode and the upper electrode is , Another layer of different material on the outer periphery And there is a step at the interface between the electrode (electrode body) and the side spacer arranged around it.

It is characterized by being less than 25 nm.

Such a piezoelectric laminated structure has excellent piezoelectric characteristics and high reliability, and a piezoelectric thin film resonator using the piezoelectric laminated structure has excellent frequency characteristics with low loss.

Further, in the piezoelectric laminated structure 14 of the piezoelectric thin film resonator of the present invention, the lower electrode 15 and the upper electrode 17 overlap each other in the thickness direction (that is, when viewed in the thickness direction of the piezoelectric laminated structure 14). It is preferable that the vibration region defined as the region is inside the edge of the membrane 21 (that is, the outer peripheral edge of the vibration space 20). By maintaining such a positional relationship, the Q value of the piezoelectric thin film resonator can be increased. When the vibration region extends outside the membrane edge, the Q value of the piezoelectric thin film resonator tends to decrease.

[0082] Furthermore, the distance between the end (edge) of the vibration region and the membrane edge (corresponding to the outer periphery of the vibration space) is w, and the thickness of the piezoelectric laminated structure 14 in the vibration region is insulated from the thickness. When the total thickness of the layers (lower insulating layer and upper insulating layer) is t, by setting the value of wZt to 0 and within the range of wZt≤ 2, the high Q value with a large electromechanical coupling coefficient A piezoelectric thin film resonator having the above can be realized. Moreover, in the piezoelectric thin film resonator having such a positional relationship, spurious generation in the pass band is suppressed. In the range of wZt> 2, spurious due to unnecessary transverse acoustic mode tends to occur.

The resistances of the lower electrode 15 and the upper electrode 17 affect the loss of resonance characteristics. Therefore, in the present invention, it is preferable to control the formation conditions of the metal thin film so that the specific resistance of the lower electrode and the upper electrode, which cause the loss of the input signal, becomes a sufficiently small value. For example, the specific resistance of the electrode is controlled to be 5 to 20 Ω'cm. By setting the specific resistance to a value within this range, it is possible to reduce the loss of the input high-frequency signal and realize good resonance characteristics.

In the piezoelectric thin film resonator having the configuration shown in FIGS. 4A and 4B, a Balta elastic wave is excited by applying a voltage to the upper and lower electrodes 15, 17 of the piezoelectric thin film 16. For this reason, it is necessary to expose the lower electrode 15 to be a terminal electrode. To construct a filter using resonators with this configuration, it is necessary to connect two or more resonators in combination. In this case, if the electric resistance of the metal thin film is large, loss due to the connection wiring occurs. . For this reason, in the present invention, the conditions for forming the metal thin film are controlled so that the specific resistance of the lower electrode 15 and the upper electrode 17 that cause the loss of the input signal becomes a sufficiently small value. For example, by controlling the electrode specific resistance to be 5 to 20 Ω'cm, it is possible to reduce the loss of the input high-frequency signal and realize good filter performance.

FIG. 7A is a schematic plan view showing another embodiment of the piezoelectric thin film resonator according to the present invention, and FIGS. 7B and 7C are an XX sectional view and a YY sectional view, respectively. FIG. 7D is an enlarged view of a portion surrounded by a dotted line in FIG. 7C. In these drawings, members having the same functions as those in FIGS. 4A, 4B and 4C are given the same reference numerals.

In the present embodiment, the piezoelectric thin film resonator 10 includes a substrate 11, a lower insulating layer 13 formed on the upper surface of the substrate 11, and a piezoelectric laminated structure 14 formed on the upper surface of the lower insulating layer 13. Furthermore, an upper insulating layer 23 is formed on the upper surface of the piezoelectric laminated structure 14. The piezoelectric laminated structure 14 includes a lower electrode 15 formed on the upper surface of the insulating layer 13, a piezoelectric thin film 16 formed on the upper surface of the lower insulating layer 13 so as to cover a part of the lower electrode 15, and the piezoelectric thin film 16 An upper electrode 17 formed on the upper surface of the piezoelectric thin film 16 is included. The lower electrode 15 has a shape close to a rectangle and has a main body 15a and a terminal 15b for connecting the main body 15a to an external circuit.

The upper electrode 17 has a main body portion 17a formed in a region corresponding to the vibration space 20, and a terminal portion 17b for connecting the main body portion 17a and an external circuit. The terminal portions 15b and 17b are located outside the region corresponding to the vibration space 20.

[0088] At least one of lower electrode 15 and upper electrode 17 includes a layer containing molybdenum as a main component. It is formed with a metal thin film of ~ 450nm. For example, the lower electrode 15 is made of a metal thin film mainly composed of molybdenum and has a thickness of 150 to 450 nm. The upper electrode 17 is a laminate of a metal thin film with a thickness of d3 mainly composed of molybdenum and a metal thin film with a thickness of d4 mainly composed of aluminum, and the thicknesses d3 and d4 of the respective metal thin films are d4 / d3> l Powerful 150nm <(d3 + d4) <450nm and! /, satisfying the relationship! The d3 metal thin film, which has high acoustic impedance and is mainly composed of highly oriented molybdenum thin film, is interposed between the d4 metal thin film, whose main component is aluminum, and the piezoelectric thin film. It is preferable. Aluminum nitride (A1N), aluminum oxynitride (AIO N), aluminum oxide (Al 2 O 3), silicon nitride (SiN), silicon oxynitride (Si ON), and acid zirconium oxide

2 3 2 2

(ZrO) and acid tantalum (Ta 2 O) group force at least one material selected

2 2 5

Is formed in contact with the lower surface of the lower electrode. Similarly, if necessary, aluminum nitride (A1N), aluminum oxynitride (AIO N), aluminum oxide (Al 2 O 3) ), Silicon nitride (SiN), silicon oxynitride (Si ON), zirconium oxide (ZrO)

2 3 2 2 2 and group power consisting of tantalum oxide (Ta 2 O 3)

twenty five

An upper insulating layer 23 is formed in contact with the upper surface of the upper electrode.

[0089] The SiO layer on the lower surface of the substrate 11 on which the piezoelectric multilayer structure 14 is formed as described above is formed by photo

2

Patterned into a predetermined shape by lithography 1 and, if necessary, coated with a photoresist for micromachining, and the same as the SiO mask on the bottom surface of the substrate by photolithography.

2 Form a resist mask with a single shape. The substrate 11 on which the mask was formed was loaded into a dry etching system with Deep RIE (deep engraved reactive ion etching) specifications, and SF inside

6 Gas and CF gas are introduced alternately, and etching and sidewall protection are repeated.

4 8

By controlling the etching rate ratio between the surface and the bottom surface, the vibration space 20 having a depth, a prismatic shape, or a columnar shape with the side walls standing vertically is formed. As a result, as shown in FIGS. 7B and 7C, it is possible to obtain a vibration space in which the membrane 21 and the opening on the back surface of the substrate have substantially the same planar shape and dimensions.

[0090] In the present invention, a side spacer made of a material different from the electrode is provided around the outer periphery of the lower electrode or the upper electrode, and the side spacer is formed in a slope shape, Crater-like separation is achieved by forming an aluminum nitride piezoelectric thin film between the upper and lower electrodes produced by controlling the processing method so that the step at the interface between the electrode and the side spacer is less than 25 nm. A highly oriented and highly crystalline c-axis oriented aluminum nitride thin film with no growth can be obtained, and the adverse effects on the piezoelectric properties due to the tilt of the edge of the lower electrode or upper electrode can be eliminated.

[0091] As shown in FIG. 7D, the inclination angle of the upper surface of the electrode body with respect to the lower surface is Θ

2 is defined, and the angle of inclination with respect to the lower surface of the upper surface of the slope in the side spacer formed in a slope shape is defined as 0 1. On the lower surface of the upper surface of the slope of the side spacer The tilt angle θ 1 is 3 to 45 °. When the inclination angle θ 1 is smaller than 3 °, the slope length becomes too long, and it becomes difficult to ensure the dimensional accuracy in the plane direction of each layer constituting the piezoelectric thin film resonator. Piezoelectric properties such as coupling coefficient and acoustic quality factor (Q value) deteriorate. When the inclination angle θ 1 exceeds 45 °, crater-like separated growth of the aluminum nitride piezoelectric thin film tends to occur easily from the boundary between the electrode body and the side spacer or from one end of the side spacer.

In addition, regarding the shape of the end portion of the electrode body in contact with the side spacer, it is preferable that the inclination angle Θ 2 with respect to the lower surface of the upper surface of the electrode body is 70 to 90 ° (ie, vertical). By setting the angle of inclination Θ 2 to 70-90 °, the acoustic quality factor (Q value) of the obtained piezoelectric thin film resonator is improved, and characteristics such as insertion loss, roll-off steepness, and cutoff characteristics are excellent. High performance piezoelectric thin film resonators can be manufactured.

Using the configuration of the piezoelectric thin film resonator of the present invention, a multilayer piezoelectric thin film resonator having the piezoelectric thin film resonator of the present invention can be manufactured. That is, the multilayer piezoelectric thin film resonator of the present invention has a substrate 11 made of a semiconductor or an insulator having a vibration space 20 and a surface facing at least the vibration space 20 on the substrate, as shown in FIGS. The lower insulating layer 13 and the piezoelectric laminated structure are sequentially arranged in a region including the region to be processed. The piezoelectric laminated structure has a lower electrode 15, a first aluminum nitride piezoelectric thin film 16-1, an internal electrode 17 ′, a second aluminum nitride piezoelectric thin film 16-2, and an upper electrode 18. At least one of the lower electrode 15, the internal electrode 17 ′, and the upper electrode 18 has a side spacer 26, which is another layer made of a different material, around the outer peripheral portion thereof. The step at the interface with spacer 26 is less than 25 nm.

This embodiment is a SBAR having a piezoelectric laminated structure corresponding to a laminate of two piezoelectric laminated structures according to the embodiments shown in FIGS. 7 to 7D. That is, the lower electrode 15, the first piezoelectric thin film 16-1, the internal electrode 17 ', the second piezoelectric thin film 16-2, and the upper electrode 18 are formed on the lower insulating layer 13 in this order. The internal electrode 17 'has a function as an upper electrode for the first piezoelectric thin film 16-1 and a function as a lower electrode for the second piezoelectric thin film 16-2. That is, the multilayer piezoelectric thin film resonator (SBAR) of the present invention has a structure including the configurations of the lower electrode, the piezoelectric layer, and the upper electrode of the present invention, and the pressure of the present invention. It is one Embodiment of an electrothin film resonator.

In the present embodiment, an input voltage can be applied between the lower electrode 15 and the internal electrode 17 ′, and the voltage between the internal electrode 17 ′ and the upper electrode 18 can be taken out as an output voltage. This itself can be used as a multipole filter. By using a multipole filter having such a configuration as a component of a passband filter, the attenuation characteristics of the stopband are improved and the frequency response as a filter is improved.

[0096] In the piezoelectric thin film resonator as described above, the resonance frequency f and antiresonance frequency f in the impedance characteristics measured using a microwave prober are related to the electromechanical coupling.

r a

Between the number k ^2, the following relationship.

Φ = (π / 2) (f / f)

For simplicity, the electromechanical coupling coefficient k ² was calculated using the following force.

k 4.8

t ² = (fafr) Z (fa + fr)

[0097] In the piezoelectric thin film resonator or laminated piezoelectric thin film resonator having the configuration shown in FIGS. 4A to 4C, FIGS. 7A to 7D, and FIGS. 8A and 8B, the resonance frequency and the anti-resonance in the range of 1.5 to 2.5 GHz. The electromechanical coupling coefficient k ² obtained from the measured resonance frequency is 6.0% or more. When the electromechanical coupling coefficient k ² is less than 6.0%, the bandwidth of the piezoelectric thin film filter manufactured by combining these piezoelectric thin film resonators is reduced, and it is practically used as a piezoelectric thin film device used in a high frequency range. It tends to be difficult to provide.

According to the present invention, a piezoelectric thin film such as a VCO (voltage controlled oscillator), a filter, and a duplexer is used by using the piezoelectric thin film resonator of the present invention and a laminated piezoelectric thin film resonator as one form thereof. An excellent piezoelectric thin film device having a resonator can be provided.

FIG. 9 shows a schematic plan view of a thin film piezoelectric filter as an embodiment of the piezoelectric thin film device of the present invention. In the present embodiment, five piezoelectric thin film resonators 2 10, 220, 230, 240, and 250 are formed using a common substrate. These piezoelectric thin film resonators are all of the embodiment shown in FIGS. 7A and 7B. The lower electrode terminal portions 15b of the piezoelectric thin film resonators 210, 220, and 240 are connected to each other, and the upper electrode terminal portions 17b of the piezoelectric thin film resonators 220, 230, and 250 are connected to each other. Upper part of piezoelectric thin film resonator 210 The electrode terminal portion and the lower electrode terminal portion of the piezoelectric thin film resonator 230 are input / output terminals, and the upper electrode terminal portion of the piezoelectric thin film resonator 240 and the lower electrode terminal portion of the piezoelectric thin film resonator 250 are grounded. In FIG. 9, the same applies to the force of the piezoelectric laminated structure 14 shown only for the piezoelectric thin film resonator 220 and other piezoelectric thin film resonators. Further, although the side spacers are not shown in FIG. 9, the side spacers for the upper electrode and the lower electrode as described with reference to FIGS. 7A and 7B are provided.

[0100] The piezoelectric thin film device of the present invention is not particularly limited to the above device as long as it has a piezoelectric thin film resonator and a laminated piezoelectric thin film resonator which is one form thereof.

Example

[0101] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. For the following examples and comparative examples, an air gap type piezoelectric thin film resonator is manufactured. However, an acoustic mirror type piezoelectric thin film resonator can also be manufactured by the same technique.

[0102] (Example 1)

In this example, a piezoelectric thin film resonator having the structure shown in FIGS. 4A, 4B, and 4C was fabricated as follows.

That is, a 1500 nm thick SiO layer is formed on both sides of a 625 μm thick Si wafer by thermal oxidation.

2), a 50 nm thick Ti thin film is deposited as a sacrificial layer on the SiO layer on the upper surface of the Si wafer.

2

Then, a pattern was formed into a desired air bridge shape (that is, a shape corresponding to a desired vibration space) by photolithography. Next, the lower insulating layer (lower insulating layer) with the thickness shown in Table 1 is formed on the exposed surfaces of the sacrificial layer and the SiO layer by reactive sputtering.

2

An Al 2 O thin film was formed. On this lower insulating layer, by DC magnetron sputtering method,

twenty three

A Mo thin film having the thickness shown in Table 1 was deposited to form a lower electrode (lower electrode layer: lower electrode body), and further patterned by photolithography. Subsequently, a silicon oxide (SiO 2) film was deposited to a thickness of 300 to 900 nm on the exposed surfaces of the lower electrode and the lower insulating layer by a low pressure CVD method using TEOS (Tera-ethoxy silane) as a raw material. Different using ICP plasma

2

The surface of the lower electrode is exposed by anisotropic dry etching, and the SiO

2 Etch back until the surface of the film is smoothly connected to the surface of the lower electrode, leaving the SiO film only around the side wall of the patterned lower electrode, and the side spacer of the desired structure. Formed one.

As a result of evaluating the crystal orientation of the lower electrode using an X-ray diffractometer, as shown in Table 1, the rocking curve FWHM of the Mo (110) plane was 2.3 deg. A1 target with a purity of 99.999% is used on the exposed surface of the lower Mo electrode and side spacer and Al 2 O thin film.

twenty three

On the other hand, an A1N thin film having a thickness of 1. O / z m as a piezoelectric thin film (piezoelectric thin film) was formed by reactive RF magnetron sputtering under the conditions shown in Table 3. As a result of evaluating the crystallinity of the A1N thin film by the X-ray diffraction method, only peaks corresponding to the c-plane including the (0002) plane were observed. As shown in Table 3, the rocking 'curve half-width (FWHM) was 1 It was 6 °. Next, the Mo thin film having the thickness shown in Table 2 is deposited on the piezoelectric thin film by DC magnetron sputtering to form the upper electrode (upper electrode layer: upper electrode main body), and photolithography is performed to obtain FIG. 4A. As shown in the figure, it was patterned in a shape close to a rectangle with a plane size of 150 X 170 m (the opposite side was slightly non-parallel). Next, the piezoelectric thin film was patterned into a predetermined shape by dry etching. On the exposed surface of the lower electrode and its side spacers, piezoelectric thin film, upper electrode, and lower insulating layer, an Al 2 O thin film with the thickness shown in Table 2 serving as the upper insulating layer (upper insulating layer) is formed. Deposited and patterned. Next, the lower electrode and its side

twenty three

A photoresist is applied to the exposed surface of the sensor, piezoelectric thin film, upper electrode, upper insulating layer, and lower insulating layer, and a via hole is formed at a position corresponding to the via hole for forming the vibration space shown in FIG. 4B. Form a pattern and dry etch using mixed gas of C1 and Ar

2

Opened a via hole. The SiO layer on the lower side of the Si wafer without stripping the photoresist was also covered with photoresist. Diluted hydrofluoric acid aqueous solution is used as an etchant,

2

By etching solution circulation through the via hole, the Ti sacrificial layer and the 1500 nm thick SiO layer located below it were removed by etching. Recording by oxygen ashing in oxygen plasma

2

The vibration space 20 shown in FIG. 4B was created by removing the dies. Through the above manufacturing process, a piezoelectric thin film resonator having the structure shown in FIGS. 4A, 4B and 4C was manufactured. Tables 1 to 3 show the material and thickness of each layer in the vibration region, Table 1 shows the bottom electrode rocking curve half width (FWHM), and Table 3 shows the piezoelectric thin film formation conditions and rocking curve half width (FWHM). ) And other crystalline properties.

[0105] Table 1 and Table 2 show the inclination angle θ 1 of the end face of the side spacer 1 and the end face of the electrode body. The inclination angle θ 2 is shown. These are the angles between the end surface (end surface or top surface) and the bottom surface of each layer shown in FIG. 7D.

[0106] In addition, the impedance characteristic between the electrode terminals 15b and 17b of the piezoelectric thin-film resonator is measured using a cascade 'Microtech GSG micro prober and a network analyzer' to obtain the parameter "Scattering". From the measured values of the resonance frequency f and antiresonance frequency f, the electromechanical coupling coefficient k ² is

The peak quality of the peak and antiresonance peak (peak width at a position 3 dB away from the peak top) and the acoustic quality factor Q of the resonance peak and antiresonance peak were also obtained. Thickness vibration fundamental frequency, electromechanical coupling coefficient k ² , acoustic quality factor Q, insertion loss minimum value (forward transmission coefficient, value at the resonance point of S) and spurious characteristics of the obtained piezoelectric thin film resonator

twenty one

Were as shown in Table 3.

[Example 2]

In this example, a piezoelectric thin film resonator having the structure shown in FIGS. 4A, 4B, and 4C was fabricated as follows. That is, the material and thickness of the lower insulating layer and the upper insulating layer, the formation condition and thickness of the lower electrode, the material and inclination angle of the side spacer, the formation condition and thickness of the A1N piezoelectric thin film, and the material of the upper electrode The piezoelectric thin film resonator shown in FIGS. 4A, 4B, and 4C was manufactured using the same method as in Example 1 except that the thickness was changed. Tables 1 to 3 show the material and thickness of each layer in the vibration region, Table 1 shows the bottom electrode rocking 'curve half width (F WHM), and Table 3 shows the piezoelectric thin film formation conditions and rocking' curve half width (FWHM). ) Etc. were described.

[0108] In addition, using a cascade 'Microtech GSG micro prober and a network analyzer', the impedance characteristics between the electrode terminals 15b and 17b of the piezoelectric thin film resonator are measured to obtain the 'suttering' parameter. From the measured values of the resonance frequency f and antiresonance frequency f, the electromechanical coupling coefficient k ² is

The peak quality of the peak and antiresonance peak (peak width at a position 3 dB away from the peak top) and the acoustic quality factor Q of the resonance peak and antiresonance peak were also obtained. Thickness vibration fundamental frequency, electromechanical coupling coefficient k ² , acoustic quality factor Q, insertion loss minimum value (forward transmission coefficient, value at the resonance point of S) and spurious characteristics of the obtained piezoelectric thin film resonator Were as shown in Table 3.

[Example 3]

In this example, a piezoelectric thin film resonator having the structure shown in FIGS. 4A, 4B, and 4C was fabricated as follows. That is, after forming a lOOOnm thick SiO layer on both sides of a 625 m thick Si wafer by thermal oxidation, it becomes a sacrificial layer on the SiO layer on the upper surface of the Si wafer.

twenty two

A Ti thin film with a thickness of 80 nm was deposited and patterned into a desired air bridge shape by photolithography. Next, the sacrificial layer and the SiO layer are formed by reactive sputtering.

2 On the exposed surface, a lower insulating layer with the materials and thicknesses listed in Table 1 was formed. On this lower insulating layer, a Mo thin film having a thickness shown in Table 1 was deposited by DC magnetron sputtering to form a lower electrode, and further patterned by photolithography. In forming the pattern, the resist was exposed to ultraviolet light that was intentionally defocused and developed to make the resist shape into a gentle saddle shape. We focused on controlling the tilt angle Θ 2 of the electrode pattern end face (sidewall) during dry etching by providing a gentle slope on the resist end face.

[0110] As a result of evaluating the crystal orientation of the lower electrode using an X-ray diffractometer, the rocking curve FWHM of the Mo (110) plane was 1.5 deg as shown in Table 1. An A1N thin film as a piezoelectric thin film was formed on the exposed surfaces of the lower Mo electrode and lower insulating layer by reactive RF magnetron sputtering using an A1 target with a purity of 99.999% under the conditions shown in Table 3. Formed. As a result of evaluating the crystallinity of the A1N piezoelectric thin film by the X-ray diffraction method, only peaks corresponding to the c-plane, including the (0002) plane, were observed. As shown in Table 3, the rocking 'curve full width at half maximum (FWHM) was 1. It was 0 °. Next, an upper electrode is formed by depositing a Mo thin film having the thickness shown in Table 2 on the piezoelectric thin film by DC magnetron sputtering, and a planar dimension 150 X 170 as shown in FIG. 4A by photolithography. It is close to the rectangle of m and patterned in a shape (the opposite side is slightly non-parallel).

[0111] Subsequently, a 300-900 nm thick silicon oxynitride (Si ON) film was deposited on the exposed surfaces of the lower electrode, the piezoelectric thin film, the upper electrode, and the lower insulating layer by a low pressure CVD method. ICP plasma

twenty two

Etch back until the surface of the upper electrode is exposed and the surface of the Si ON film in contact with the side wall of the upper electrode is smoothly connected to the surface of the upper electrode by anisotropic dry etching using Leave the Si ON film only around the sidewall of the upper electrode that has been turned, leaving the desired structure.

twenty two

A side spacer was formed.

[0112] Next, the piezoelectric thin film was patterned into a predetermined shape by dry etching and subsequent wet etching. On the exposed surface of the lower electrode, piezoelectric thin film, upper electrode and its side spacers, and lower insulating layer, a thin film of the material and thickness described in Table 2 serving as the upper insulating layer was deposited and patterned. . Next, a photoresist is applied on the exposed surface of the lower electrode, piezoelectric thin film, upper electrode and its side spacer, upper insulating layer, and lower insulating layer to form the vibration space shown in FIG. 4B. Dry Ettin using a mixed gas of C1 and Ar with a via hole pattern formed at a position corresponding to the via hole of

2

Opened a via hole. The SiO layer on the lower surface side of the Si wafer without peeling off the photoresist was also coated with the photoresist. Diluted hydrofluoric acid aqueous solution is used as the etchant, and

2

The Ti sacrificial layer and the SiO layer with a thickness of 1 OOOnm below it were removed by etching by circulating the etching solution through the hole. Cash register by ashing in oxygen plasma

2

The vibration space 20 shown in FIG. 4B was created by removing the strike. The piezoelectric thin film resonator having the structure shown in FIGS. 4A, 4B and 4C was manufactured by the above manufacturing process. Tables 1 to 3 show the material and thickness of each layer in the vibration region, Table 1 shows the bottom electrode rocking curve half width (FWHM), and Table 3 shows the piezoelectric thin film formation conditions and rocking 'curve half width (FWHM). The crystal properties such as

[0113] Further, the high frequency characteristics and resonance characteristics of the piezoelectric thin film resonator were evaluated by the same impedance characteristic measurement as in Example 1. The resulting fundamental frequency of thickness vibration of the piezoelectric thin film resonator, the electromechanical coupling coefficient k ^2, the acoustic quality factor Q, the insertion loss minimum value and spurious characteristic (forward transmission coefficient, the value at the resonance point of S), the table It was as shown in 3.

twenty one

[0114] (Example 4)

In this example, a piezoelectric thin film resonator having the structure shown in FIGS. 7A and 7B was produced as follows.

That is, by forming a SiO layer having a thickness of lOOOnm on both sides of a (100) Si substrate having a thickness of 300 m by thermal oxidation, it corresponds to the shape of the desired vibration space 20 on the SiO layer on the lower surface of the Si substrate. Shi

twenty two

A mask pattern is formed, and the SiO layer in the region corresponding to the pattern is removed by etching. It was. At the same time, the entire SiO layer on the upper surface of the Si substrate was removed by etching. Next, reactive spatter

2

The bottom layer of the materials and thicknesses listed in Table 1 are formed on the SiO layer on the top surface of the Si substrate by the tulling method.

2

An edge layer was formed. On this lower insulating layer, the lower electrode was formed by sequentially depositing a Cr adhesion layer and a Mo thin film of the materials and thicknesses shown in Table 1 by DC magnetron sputtering, and then patterning by photolithography. . When forming the pattern, the resist was exposed to intentionally defocused ultraviolet light and developed to give the resist a gentle bowl shape. Focusing on controlling the tilt angle Θ 2 of the electrode pattern end face (sidewall) during dry etching by providing a gentle slope on the resist end face.

[0115] As a result of evaluating the crystal orientation of the lower electrode using an X-ray diffractometer, as shown in Table 1, the rocking curve FWHM of the Mo (110) plane was 1.8 deg. An A1N thin film as a piezoelectric thin film was formed on the exposed surfaces of the lower Mo electrode and the lower insulating layer by reactive RF magnetron sputtering using an A1 target with a purity of 99.999% under the conditions shown in Table 3. . As a result of evaluating the crystallinity of the A1N piezoelectric thin film by the X-ray diffraction method, only peaks corresponding to the c-plane, including the (0002) plane, were observed. As shown in Table 3, the rocking 'curve half-width (FWHM) ) Was 1.3 °.

Next, an upper electrode is formed by sequentially depositing the Mo thin film and the A1 thin film having the thicknesses shown in Table 2 on the piezoelectric thin film by DC magnetron sputtering, and the upper electrode is formed by photolithography, as shown in FIG. 7A. Thus, it was patterned in a shape close to a rectangle with a plane size of 140 x 160 m (the opposite side was slightly non-parallel). Subsequently, a silicon oxide (SiO 2) film is formed on the exposed surfaces of the lower electrode, piezoelectric thin film, upper electrode, and lower insulating layer by plasma CVD.

Deposited from 2 to 900 nm. Etch back until the surface of the upper electrode is exposed by anisotropic dry etching using ICP plasma, and the surface of the SiO film in contact with the side wall of the upper electrode is smoothly connected to the surface of the lower electrode.

2

As a result, the SiO film is left only around the outer peripheral side wall of the patterned lower electrode.

2 to form a side spacer. Next, the piezoelectric thin film was patterned into a predetermined shape by dry etching.

[0117] Furthermore, the materials and thicknesses listed in Table 2 that will form the upper insulating layer on the exposed surface of the lower electrode, the piezoelectric thin film, the upper electrode and its side spacers, and the lower insulating layer by reactive sputtering. A thin film was deposited and patterned by a lift-off method. [0118] The lower electrode, the piezoelectric thin film, the upper electrode and its side spacer, the upper insulating layer, and the exposed surface of the lower insulating layer are covered with protective wax, and patterned SiO 2 on the lower surface of the Si substrate. Etching Fukahori using SF gas and CF gas alternately using the layer as a mask

2 6 4 8

Using the deep RIE (Reactive Ion Etching) method, the silicon substrate in the region corresponding to the membrane is etched away to form a vibration space, and a piezoelectric thin film resonator with the structure shown in Figs. 7A, 7B, and 7C is manufactured. did. Tables 1 to 3 show the material and thickness of each layer in the vibration region, Table 1 shows the rocking curve half-width (FWHM) of the lower MoZCr laminated electrode, and Table 3 shows the A1N piezoelectric thin film formation conditions and rocking 'curve half-width. Crystal properties such as (FWHM) are described.

[0119] Further, the high frequency characteristics and resonance characteristics of the piezoelectric thin film resonator were evaluated by the same impedance characteristic measurement as in Example 1. The resulting fundamental frequency of thickness vibration of the piezoelectric thin film resonator, the electromechanical coupling coefficient k ^2, the acoustic quality factor Q, the insertion loss minimum value (forward transmission coefficient, S

The values at 21 resonance points) and spurious characteristics are shown in Table 3.

[0120] (Examples 5 and 6)

In this example, a piezoelectric thin film resonator having the structure shown in FIGS. 7A, 7B and 7C was produced as follows. That is, the material and thickness of the lower insulator layer and the upper insulator layer, the material and formation conditions and thickness of the lower electrode and the upper electrode, and the formation conditions of the A1N piezoelectric thin film are changed. A piezoelectric thin film resonator shown in FIGS. 7A, 7B, and 7C was manufactured in the same manner as in Example 4 except that a side spacer was provided around the end. Tables 1 to 3 show the material and thickness of each layer in the vibration region, Table 1 shows the bottom electrode plugging 'curve half width (FWHM), and Table 3 shows the piezoelectric thin film formation conditions and rocking' force half width. Crystal properties such as (FWHM) are described.

[0121] Further, the high frequency characteristics and resonance characteristics of the piezoelectric thin film resonator were evaluated by the same impedance characteristic measurement as in Example 1. The resulting fundamental frequency of thickness vibration of the piezoelectric thin film resonator, the electromechanical coupling coefficient k ^2, the acoustic quality factor Q, the insertion loss minimum value and spurious characteristic (forward transmission coefficient, the value at the resonance point of S), the table It was as shown in 3.

twenty one

[0122] [Table 1] ^ [] 0123

[] 0124

* Value when the vibration area is inside the membrane edge, positive, and when the vibration area edge overlaps the support area, negative value

(Example 7)

In this example, a piezoelectric thin film resonator having the structure shown in FIGS. 4A, 4B, and 4C was produced as follows. In other words, a low-pressure CVD SiN layer is used as the lower insulator layer, and the material and thickness of the upper and lower insulator layers, the formation conditions and materials and thickness of the lower and upper electrodes, and the formation conditions of the A1N piezoelectric thin film In the same manner as in Example 3 except that side spacers are provided around the outer peripheral edge for both the lower electrode and the upper electrode. The piezoelectric thin film resonator shown in FIGS. 4A, 4B and 4C was manufactured. Tables 1 to 3 show the material and thickness of each layer in the vibration region, Table 1 shows the bottom electrode rocking curve half width (FWHM), and Table 3 shows the piezoelectric thin film formation conditions and rocking 'curve half width (FWHM). The crystal properties such as were described.

[0126] In addition, the high frequency characteristics and resonance characteristics of the piezoelectric thin film resonator were evaluated by the same impedance characteristic measurement as in Example 1. The resulting fundamental frequency of thickness vibration of the piezoelectric thin film resonator, the electromechanical coupling coefficient k ^2, the acoustic quality factor Q, the insertion loss minimum value and spurious characteristic (forward transmission coefficient, the value at the resonance point of S), the table It was as shown in 3.

twenty one

[Examples 8 and 9]

In this example, a piezoelectric thin film resonator having the structure shown in FIGS. 4A, 4B, and 4C was fabricated as follows. That is, the material and thickness of the lower insulator layer and the upper insulator layer, the formation conditions and material and thickness of the lower electrode and the upper electrode, the material and inclination angle of the side spacer, and the formation conditions of the A1N piezoelectric thin film are changed. A piezoelectric thin film resonator having the structure described in FIGS. 4A, 4B, and 4C was used in the same manner as in Example 3 except that side spacers were provided around the outer peripheral edge of both the lower electrode and the upper electrode. Manufactured. Tables 1 to 3 show the material and thickness of each layer in the vibration region, Table 1 shows the bottom electrode rocking curve half width (FWHM), and Table 3 shows the piezoelectric thin film formation conditions and rocking 'curve half width (FWHM). The crystal properties such as

[0128] Further, the high frequency characteristics and resonance characteristics of the piezoelectric thin film resonator were evaluated by the same impedance characteristic measurement as in Example 1. The resulting fundamental frequency of thickness vibration of the piezoelectric thin film resonator, the electromechanical coupling coefficient k ^2, the acoustic quality factor Q, the insertion loss minimum value and spurious characteristic (forward transmission coefficient, the value at the resonance point of S), the table It was as shown in 3.

twenty one

[Examples 10 and 11]

In this example, a piezoelectric thin film resonator having the structure shown in FIGS. 4A, 4B, and 4C was fabricated as follows. That is, in the same manner as in Example 3, except that both the lower electrode and the upper electrode are provided with side spacers around the outer peripheral edge to form the lower insulator layer, the lower electrode, the side spacer, and the A1N thin film. After patterning, the top electrode, side spacer, and top insulator layer are formed, as shown in Figures 4A, 4B, and 4C. A piezoelectric thin film resonator having the following structure was manufactured. Tables 1 to 3 show the material and thickness of each layer in the vibration region, Table 1 shows the bottom electrode rocking curve half width (FWHM), and Table 3 shows the piezoelectric thin film formation conditions and rocking 'curve half width (FWHM). ) And other crystal properties.

[0130] Further, the high frequency characteristics and the resonance characteristics of the piezoelectric thin film resonator were evaluated by the same impedance characteristic measurement as in Example 1. The resulting fundamental frequency of thickness vibration of the piezoelectric thin film resonator, the electromechanical coupling coefficient k ^2, the acoustic quality factor Q, the insertion loss minimum value and spurious characteristic (forward transmission coefficient, the value at the resonance point of S), the table It was as shown in 3.

twenty one

[0131] (Examples 12 to 14)

In this example, a piezoelectric thin film resonator having the structure shown in FIGS. 4A, 4B, and 4C was fabricated as follows. That is, the material and thickness of the lower insulator layer and the upper insulator layer, the material of the lower electrode, the formation conditions and thickness, the material and inclination angle of the side spacer, the formation conditions of the A1N piezoelectric thin film, and the upper electrode layer Using the same method as in Example 3 except that the material and thickness were changed and side spacers were provided around the outer periphery of both the lower electrode and the upper electrode, as shown in FIGS. 4A, 4B, and 4C. A piezoelectric thin film resonator was manufactured. Tables 1 to 3 show the material and thickness of each layer in the vibration region, Table 1 shows the bottom electrode rocking 'curve half width (F WHM), and Table 3 shows the piezoelectric thin film formation conditions and rocking' curve half width (FWHM). ) Etc. were described.

[0132] Further, the high frequency characteristics and resonance characteristics of the piezoelectric thin film resonator were evaluated by the same impedance characteristic measurement as in Example 1. The resulting fundamental frequency of thickness vibration of the piezoelectric thin film resonator, the electromechanical coupling coefficient k ^2, the acoustic quality factor Q, the insertion loss minimum value and spurious characteristic (forward transmission coefficient, the value at the resonance point of S), the table It was as shown in 3.

twenty one

[0133] (Comparative Example 1)

In this comparative example, a piezoelectric thin film resonator for comparison with the structure shown in FIGS. 4A, 4B, and 4C was produced as follows. That is, the lower insulator layer and the upper insulator layer are made of a low-pressure CVD SiN layer, the lower electrode adhesion layer is Cr, and the lower electrode main layer is Mo. A piezoelectric thin film having a structure similar to that shown in FIGS. 4A, 4B and 4C by the method described in Example 3 except that the material and thickness of the lower electrode and the upper electrode were changed and a side spacer was not provided. A resonator was manufactured. table 1~ Table 3 shows the material and thickness of each layer in the vibration region, Table 1 shows the bottom electrode rocking 'curve half width (FWHM), and Table 3 shows the piezoelectric thin film formation conditions and rocking curve half width (FWHM). The properties are described.

[0134] Further, the high frequency characteristics and resonance characteristics of the piezoelectric thin film resonator were evaluated by the same impedance characteristic measurement as in Example 1. The resulting fundamental frequency of thickness vibration of the piezoelectric thin film resonator, the electromechanical coupling coefficient k ^2, the acoustic quality factor Q, the insertion loss minimum value and spurious characteristic (forward transmission coefficient, the value at the resonance point of S), the table It was as shown in 3.

twenty one

[0135] (Comparative Example 2)

In this comparative example, a piezoelectric thin film resonator for comparison with the structure shown in FIGS. 4A, 4B, and 4C was produced as follows. In other words, except that the material and thickness of the lower insulator layer and the upper insulator layer and the material and thickness of the lower electrode and the upper electrode were changed, the same method as in Comparative Example 1 was applied to FIGS. 4A, 4B, and 4C. A piezoelectric thin film resonator having a structure similar to that described was manufactured. Table 1 to Table 3 show the material and thickness of each layer in the vibration region, Table 1 shows the bottom electrode rocking 'curve half width (FWHM), and Table 3 shows the piezoelectric thin film formation conditions and rocking' curve half width (FWHM). Etc. were described.

[0136] Further, the high frequency characteristics and resonance characteristics of the piezoelectric thin film resonator were evaluated by the same impedance characteristic measurement as in Example 1. The resulting fundamental frequency of thickness vibration of the piezoelectric thin film resonator, the electromechanical coupling coefficient k ^2, the acoustic quality factor Q, the insertion loss minimum value (forward transmission coefficient, S

[0137] (Comparative Examples 3 to 6)

[0138] Further, by measuring the impedance characteristics in the same manner as in Example 1, Characteristics and resonance characteristics were evaluated. Table 3 shows the fundamental frequency of thickness vibration, electromechanical coupling coefficient ² , acoustic quality factor Q, minimum insertion loss (forward transmission coefficient, value at the resonance point of S) and spurious characteristics of the obtained piezoelectric thin film resonator. It was as shown in.

twenty one

[0139] (Comparative Example 7)

In this comparative example, a piezoelectric thin film resonator having the structure shown in FIGS. 4A, 4B, and 4C was fabricated as follows. In other words, in addition to changing the material and thickness of the lower and upper insulator layers and the material and thickness of the lower and upper electrodes, it is formed around the lower electrode body and its outer peripheral edge. A piezoelectric thin film resonator having the structure shown in FIGS. 4A, 4B, and 4C was manufactured by the method described in Example 1 except that the step at the interface with the side spacer had a large value of 30 nm. Tables 1 to 3 show the material and thickness of each layer in the vibration region, Table 1 shows the bottom electrode rocking 'curve half width (FWHM), and Table 3 shows the piezoelectric thin film formation conditions and rocking' curve half width (FWHM). Etc. were described.

[0140] Further, the high frequency characteristics and resonance characteristics of the piezoelectric thin film resonator were evaluated by the same impedance characteristic measurement as in Example 1. The resulting fundamental frequency of thickness vibration of the piezoelectric thin film resonator, the electromechanical coupling coefficient k ^2, the acoustic quality factor Q, the insertion loss minimum value and spurious characteristic (forward transmission coefficient, the value at the resonance point of S), the table It was as shown in 3.

Claims

The scope of the claims

[1] A substrate having a vibration space or an acoustic reflection layer, and a piezoelectric multilayer structure disposed so as to face the vibration space or the acoustic reflection layer, the piezoelectric multilayer structure being a vibration space or an acoustic reflection layer. A piezoelectric thin film resonator having at least a lower electrode, a piezoelectric thin film, and an upper electrode arranged in order of lateral force close to the reflective layer,

A side spacer having a different material from that of the electrode is disposed around an outer peripheral portion of at least one of the lower electrode and the upper electrode, and a step at an interface between the side spacer and the electrode. Piezoelectric thin film resonator characterized by being less than 25 nm

2. The piezoelectric thin film resonator according to claim 1, wherein the piezoelectric thin film has an aluminum nitride (A1N) force.

[3] The piezoelectric thin film according to claim 2, wherein the (0002) diffraction peak rocking 'curve half-width (FWHM) of the piezoelectric thin film having the aluminum nitride force is 0.8 to 1.6 °. Resonator.

4. The piezoelectric thin film resonator according to claim 1, wherein a step at the interface between the side spacer and the electrode is less than 3 nm.

5. The piezoelectric thin film resonator according to claim 1, wherein the side spacer 1 has an upper surface formed in a slope shape with respect to a lower surface.

6. The piezoelectric thin film resonator according to claim 1, wherein the side spacer has an upper surface tilt angle of 3 to 45 degrees with respect to the lower surface.

7. The piezoelectric thin film resonator according to claim 1, wherein an acoustic impedance of the side spacer is greater than / less than an acoustic impedance of the electrode.

[8] The piezoelectric thin film resonator according to [1], wherein the side spacer has an insulating force.

[9] The side spacer includes silicon dioxide (SiO 2), silicon nitride (SiN), and oxynitride silicon.

2

(Si ON), aluminum nitride (A1N), aluminum oxynitride (AIO N), aluminum oxide

2 2 y

From the group consisting of hum (Al 2 O 3), zirconium oxide (ZrO 2) and tantalum oxide (Ta 2 O 3)

2 3 2 2 5 Insulator strength consisting mainly of at least one material selected Item 9. The piezoelectric thin film resonator according to Item 8.

10. The piezoelectric thin film resonator according to claim 1, wherein the side spacer also has a conductor force.

[11] The side spacer is made of a conductor whose main component is at least one material selected from the group consisting of tungsten (W), tungsten silicide (WSi), and iridium (Ir). The piezoelectric thin film resonator according to claim 10.

12. The piezoelectric thin film resonator according to claim 1, wherein at least one of the upper electrode and the lower electrode has a molybdenum force.

[13] At least one of the upper electrode and the lower electrode is composed of a laminate of two kinds of metals selected from the group force of molybdenum, ruthenium, anorium, iridium, cobalt, nickel, platinum, and copper. 2. The piezoelectric thin film resonator according to claim 1, wherein

[14] The lower electrode is a laminate of a lower metal layer having a thickness dl and an upper metal layer having a thickness d2, and dl

/ d2> l and 150 nm (dl + d2) 450 nm

1. The piezoelectric thin film resonator according to 1.

[15] The lower metal layer dl of the lower electrode is a metal thin film mainly composed of aluminum.

15. The piezoelectric thin film resonator according to claim 14, wherein the upper metal layer having a thickness d2 of the lower electrode is a metal thin film mainly composed of molybdenum.

[16] The upper electrode is a laminate of a lower metal layer having a thickness of d3 and an upper metal layer having a thickness of d4, and d4

/ d3> l and 150 nm (d3 + d4) 450 nm

1. The piezoelectric thin film resonator according to 1.

[17] The lower metal layer of the upper electrode thickness d3 is a metal thin film mainly composed of molybdenum, and the upper metal layer of the upper electrode thickness d4 is a metal thin film mainly composed of aluminum. The piezoelectric thin film resonator according to claim 16, characterized in that:

[18] A vibration region defined as a region where the lower electrode and the upper electrode overlap with each other when viewed in the thickness direction of the piezoelectric multilayer structure is located on the inner side of the vibration space or the outer peripheral edge of the acoustic reflection layer. 2. The piezoelectric thin film resonator according to claim 1, wherein:

[19] The end of the vibration region and the vibration space or Is characterized in that the distance w between the outer peripheral edge of the acoustic reflection layer and the total thickness t of the piezoelectric laminated structure and the insulating layer in the vibration region satisfy the relational expression 0 <wZt≤2. Do

The piezoelectric thin film resonator according to claim 18.

20. The piezoelectric thin film resonator according to claim 1, wherein an insulating layer is attached to an upper surface or a lower surface of the piezoelectric multilayer structure.

21. The piezoelectric thin film resonator according to claim 20, wherein the insulating layer is formed in contact with a lower surface of the lower electrode.

22. The piezoelectric thin film resonator according to claim 20, wherein the insulating layer is formed in contact with the upper surface of the upper electrode.

[23] The insulating layer is made of aluminum nitride (A1N), aluminum oxynitride (AIO N), aluminum oxide (Al 2 O), silicon nitride (SiN), silicon oxynitride (Si ON), zirconium oxide (Zr

2 3 2 2

O) and group strength consisting of tantalum oxide (Ta 2 O 3)

2 2 5

21. The piezoelectric thin film resonator according to claim 20, wherein the piezoelectric thin film resonator is a component.

[24] A piezoelectric thin film device configured by combining a plurality of piezoelectric thin film resonators according to any one of claims 1 to 23.

[25] A method of manufacturing the piezoelectric thin film resonator according to claim 1,

A first step of forming a lower insulating layer on the substrate;

A second step of forming the lower electrode on the lower insulating layer;

After depositing an insulator or conductor of a different material from the lower electrode on the exposed surfaces of the lower electrode and the lower insulating layer, the upper surface of the lower electrode is exposed by etch back.

A third step of forming the side spacer for the lower electrode around the outer periphery of the lower electrode;

A piezoelectric process comprising: a sixth step of forming the piezoelectric thin film by patterning the piezoelectric material layer; and a seventh step of forming an upper insulating layer on the piezoelectric thin film and the upper electrode. Manufacturing method of thin film resonator.

[26] Between the fifth step and the sixth step, an insulator or a conductor having a different material from that of the upper electrode is deposited on the exposed surfaces of the upper electrode and the piezoelectric material layer, and then etched back. 26. The piezoelectric thin film resonance according to claim 25, wherein a step of exposing the upper surface of the upper electrode by a step and forming the side spacer for the upper electrode around the outer periphery of the upper electrode is interposed. Child manufacturing method.

[27] A method of manufacturing the piezoelectric thin film resonator according to claim 1,

A first step of forming a lower insulating layer on the substrate;

A fifth step of patterning the piezoelectric material layer to form the piezoelectric thin film; and depositing an insulator or conductor having a different material from the upper electrode on the exposed surfaces of the upper electrode and the piezoelectric thin film; A sixth step of exposing the upper surface of the upper electrode by etch back, and forming the side spacer for the upper electrode around the outer periphery of the upper electrode;

And a seventh step of forming an upper insulating layer on the piezoelectric thin film and the upper electrode. A method for manufacturing a piezoelectric thin film resonator, comprising: