Piezoelectric device

文档序号：12581 发布日期：2021-09-17 浏览：33次中文

阅读说明：本技术 压电装置 (Piezoelectric device ) 是由岸本谕卓池内伸介于 2019-09-26 设计创作，主要内容包括：压电驱动部(120)由多个层构成,直接或间接支承于基部(110)。压电驱动部(120)包含压电体层(130)、上部电极层(140)以及下部电极层(150)。上部电极层(140)配置于压电体层(130)的上侧。下部电极层(150)以夹着压电体层(130)而与上部电极层(140)的至少局部相对的方式配置。在压电驱动部(120)中,通过设有沿着上下方向贯通的贯通槽(121)而形成一对内侧面(122)。一对内侧面(122)分别包含贯通槽(121)的宽度从压电体层(130)的上端面(131)朝向下方逐渐变窄的第1窄幅部(123)。(The piezoelectric drive unit (120) is composed of a plurality of layers and is directly or indirectly supported by the base (110). The piezoelectric drive unit (120) includes a piezoelectric layer (130), an upper electrode layer (140), and a lower electrode layer (150). The upper electrode layer (140) is disposed above the piezoelectric layer (130). The lower electrode layer (150) is disposed so as to face at least a part of the upper electrode layer (140) with the piezoelectric layer (130) therebetween. A pair of inner side surfaces (122) are formed in the piezoelectric drive unit (120) by providing a through groove (121) that penetrates in the vertical direction. The pair of inner surfaces (122) each include a 1 st narrow section (123) in which the width of the through groove (121) gradually narrows downward from the upper end surface (131) of the piezoelectric layer (130).)

1. A piezoelectric device, wherein,

the piezoelectric device includes:

a base; and

a piezoelectric driving section composed of a plurality of layers and directly or indirectly supported by the base section,

the piezoelectric driving section includes: a piezoelectric layer; an upper electrode layer disposed above the piezoelectric layer; and a lower electrode layer disposed so as to face at least a part of the upper electrode layer with the piezoelectric layer interposed therebetween,

the piezoelectric driving unit has a pair of inner side surfaces formed by providing a through groove penetrating in a vertical direction,

the pair of inner surfaces include 1 st narrow portions in which the width of the through groove gradually decreases downward from the upper end surface of the piezoelectric layer.

2. The piezoelectric device according to claim 1,

the piezoelectric drive unit is indirectly supported by the base unit, and is located above the base unit without overlapping the base unit.

3. The piezoelectric device according to claim 1 or 2,

the piezoelectric layer has a 1 st corner portion continuous with an upper end surface of the piezoelectric layer and constituting at least a part of the 1 st narrow portion,

the 1 st corner portion is curved in a convex shape obliquely upward.

4. The piezoelectric device according to claim 1 or 2,

the piezoelectric layer has a 1 st inclined portion which is continuous with an upper end surface of the piezoelectric layer and constitutes at least a part of the 1 st narrow portion.

5. The piezoelectric device according to any one of claims 1 to 4,

the piezoelectric driving unit further includes an active layer disposed below each of the lower electrode layer and the piezoelectric layer,

the pair of inner side surfaces further include a 2 nd narrow portion in which the width of the through groove gradually narrows downward from an upper end surface of the active layer.

6. The piezoelectric device of claim 3,

the piezoelectric driving unit further includes an active layer disposed below each of the lower electrode layer and the piezoelectric layer,

the pair of inner side surfaces further include a 2 nd narrow portion in which the width of the through groove gradually narrows downward from an upper end surface of the active layer,

the active layer has a 2 nd corner part continuous with an upper end surface of the active layer and constituting at least a part of the 2 nd narrow part,

the 2 nd corner part is convexly curved obliquely upward,

the radius of curvature of the 1 st corner and the radius of curvature of the 2 nd corner are different from each other.

7. The piezoelectric device according to any one of claims 1 to 6,

the piezoelectric layer is composed of a single crystal piezoelectric body,

the axial direction of the polarization axis of the single crystal piezoelectric body is inclined with respect to the stacking direction of the piezoelectric driving unit.

8. The piezoelectric device of claim 7,

the axial direction of the polarization axis of the single crystal piezoelectric body is not orthogonal to the lamination direction of the piezoelectric drive unit.

9. The piezoelectric device according to any one of claims 1 to 8,

the piezoelectric layers have different thermal expansion coefficients in the stacking direction and the planar direction of the piezoelectric driving unit.

Technical Field

The present invention relates to a piezoelectric device.

Background

As a document disclosing the structure of the piezoelectric device, there is international publication No. 2017/218299 (patent document 1). The piezoelectric device described in patent document 1 includes a substrate and a thin film portion. The substrate has an opening formed so as to penetrate therethrough. The thin film portion is formed of at least one elastic layer and at least one piezoelectric layer sandwiched between an upper electrode layer and a lower electrode layer. The thin film portion is mounted on the substrate at a position above the opening. The thin film portion has a through-groove formed by etching at a position close to an end of the opening.

Documents of the prior art

Patent document

Patent document 1: international publication No. 2017/218299

Disclosure of Invention

Problems to be solved by the invention

In a piezoelectric device in which a through groove is formed in a piezoelectric driving unit including a piezoelectric layer, the temperature rises during driving. At this time, when the coefficients of thermal expansion of the piezoelectric layers are different from each other in the vertical direction and the horizontal direction, the portion facing the through groove is deformed in the piezoelectric driving unit. This causes axial disorder of the polarization axis of the piezoelectric layer, and degrades the electrical characteristics of the piezoelectric device.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a piezoelectric device in which a portion facing a through groove in a piezoelectric driving unit is reduced in deformation, thereby suppressing a decrease in electrical characteristics.

Means for solving the problems

The piezoelectric device according to the present invention includes a base portion and a piezoelectric driving portion. The piezoelectric driving unit is composed of a plurality of layers and is directly or indirectly supported by the base. The piezoelectric driving unit includes a piezoelectric layer, an upper electrode layer, and a lower electrode layer. The upper electrode layer is disposed above the piezoelectric layer. The lower electrode layer is disposed so as to face at least a part of the upper electrode layer with the piezoelectric layer interposed therebetween. The piezoelectric driving unit has a pair of inner side surfaces formed by providing through grooves that penetrate in the vertical direction. The pair of inner surfaces each include a 1 st narrow portion in which the width of the through groove gradually narrows downward from the upper end surface of the piezoelectric layer.

ADVANTAGEOUS EFFECTS OF INVENTION

The deformation of the portion facing the through groove in the piezoelectric driving unit can be reduced, and the deterioration of the electrical characteristics of the piezoelectric device can be suppressed.

Drawings

Fig. 1 is a plan view of a piezoelectric device according to embodiment 1 of the present invention.

Fig. 2 is a sectional view of the piezoelectric device of fig. 1 as viewed in the direction of arrows ii-ii.

Fig. 8 is a cross-sectional view showing a state in which a laminate is bonded to the lower surface of an intermediate layer in the method for manufacturing a piezoelectric device according to embodiment 1 of the present invention.

Fig. 18 is a diagram showing a state in which a recess is dug down to a lower base portion in the method for manufacturing a piezoelectric device according to embodiment 1 of the present invention.

Fig. 19 is a sectional view of a piezoelectric device according to embodiment 2 of the present invention.

Fig. 24 is a view showing a state in which a recess is dug down to a lower base portion in the method for manufacturing a piezoelectric device according to embodiment 2 of the present invention.

Fig. 25 is a sectional view of a piezoelectric device according to embodiment 3 of the present invention.

Fig. 29 is a cross-sectional view showing a state after a base portion is bonded to a lower surface of an intermediate layer in the method for manufacturing a piezoelectric device according to embodiment 3 of the present invention.

Fig. 36 is a view showing a state in which a concave portion is dug down to a base portion in the method for manufacturing a piezoelectric device according to embodiment 3 of the present invention.

Detailed Description

Hereinafter, a piezoelectric device according to each embodiment of the present invention will be described with reference to the drawings. In the following description of the embodiments, the same or corresponding portions in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

(embodiment mode 1)

Fig. 1 is a plan view of a piezoelectric device according to embodiment 1 of the present invention. Fig. 2 is a sectional view of the piezoelectric device of fig. 1 as viewed in the direction of arrows ii-ii. In fig. 1, the internal structure of the piezoelectric device is shown by a dotted line.

As shown in fig. 1 and 2, a piezoelectric device 100 according to embodiment 1 of the present invention includes a base portion 110 and a piezoelectric drive portion 120.

As shown in fig. 2, the base 110 includes a lower base 110a and an upper base 110b located on an upper side of the lower base 110 a. The base 110 has an upper main surface 111 and a lower main surface 112 located on the opposite side of the upper main surface 111.

In the present embodiment, the upper surface of the upper base 110b is an upper main surface 111, and the lower surface of the lower base 110a is a lower main surface 112. The base 110 has openings 113 that penetrate the lower base 110a and the upper base 110b in the vertical direction.

The material constituting the base 110 is not particularly limited. In the present embodiment, the lower base 110a is made of Si. The upper base 110b is made of SiO₂And (4) forming.

As shown in fig. 2, a plurality of layers are stacked on the upper main surface 111 of the base 110. In the present embodiment, the piezoelectric driving unit 120 is a portion of the plurality of layers located above the opening 113. That is, the piezoelectric driving unit 120 is composed of a plurality of layers.

In the present embodiment, the piezoelectric driving unit 120 is located above the opening 113 of the base 110, and therefore does not overlap the base 110. That is, the piezoelectric drive unit 120 is indirectly supported by the base 110 and is located above the base 110. That is, in the present embodiment, the piezoelectric driving unit 120 is configured in a thin film structure. The piezoelectric driving unit 120 may be directly supported by the base 110.

As shown in fig. 2, in the present embodiment, the plurality of layers constituting the piezoelectric driving unit 120 include a piezoelectric layer 130, an upper electrode layer 140, a lower electrode layer 150, an intermediate layer 160, and an active layer 170.

The piezoelectric layer 130 is located above the base 110. The piezoelectric layer 130 is disposed such that a part of the piezoelectric layer 130 is included in the piezoelectric driving unit 120. The upper end surface 131 and the lower end surface 132 of the piezoelectric layer 130 are flat, respectively.

The piezoelectric layer 130 has a hole 133 different from a through groove described later. The hole 133 is formed to penetrate the piezoelectric layer 130 in the up-down direction. In the present embodiment, the hole 133 is located above the base 110 and is not included in the piezoelectric driving unit 120.

In the present embodiment, the piezoelectric layer 130 is made of a single crystal piezoelectric material, specifically, lithium tantalate or lithium niobate. The polarization axis of a single crystal piezoelectric material such as lithium tantalate or lithium niobate is constant in the axial direction.

The axis of polarization of the single crystal piezoelectric body is inclined with respect to the stacking direction of the piezoelectric driving unit 120. The axial direction of the polarization axis of the piezoelectric monocrystal is not orthogonal to the stacking direction of the piezoelectric drive unit 120. That is, in the present embodiment, the piezoelectric layer 130 is formed of a single crystal piezoelectric body that is cut by rotation.

In the present embodiment, since the piezoelectric layer 130 is formed of a single crystal piezoelectric body, the coefficients of thermal expansion of the piezoelectric layer 130 are different between the lamination direction and the planar direction of the piezoelectric driving unit 120.

The piezoelectric layer 130 may not be formed of a single crystal piezoelectric material. When the piezoelectric layer 130 is not formed of a single crystal piezoelectric material, the piezoelectric layer 130 may be formed such that the coefficients of thermal expansion of the piezoelectric layer 130 are different between the lamination direction and the planar direction of the piezoelectric driver 120.

The upper electrode layer 140 is disposed above the piezoelectric layer 130. The upper electrode layer 140 is disposed so that part of the upper electrode layer 140 is included in the piezoelectric drive unit 120.

In this embodiment, the upper electrode layer 140 is laminated on a part of the piezoelectric layer 130. Further, an adhesion layer made of Ti, NiCr, or the like may be disposed between the upper electrode layer 140 and the piezoelectric layer 130.

The lower electrode layer 150 is disposed so as to face at least a part of the upper electrode layer 140 with the piezoelectric layer 130 interposed therebetween. The lower electrode layer 150 is disposed such that a part of the lower electrode layer 150 is included in the piezoelectric driving unit 120. The lower electrode layer 150 is disposed in the piezoelectric driving unit 120 so as to face at least a part of the upper electrode layer 140 with the piezoelectric layer 130 interposed therebetween. Further, an adhesion layer made of Ti, NiCr, or the like may be disposed between the lower electrode layer 150 and the piezoelectric layer 130.

A part of the lower electrode layer 150 is disposed so as to be located below the hole 133 formed in the piezoelectric layer 130. In this embodiment, the lower electrode layer 150 is connected to the piezoelectric layer 130 through the etching stopper layer 155. The etching stopper layer 155 is formed to cover the lower portion of the hole 133 of the piezoelectric layer 130.

In this embodiment, a part of the lower electrode layer 150 is disposed under the etch stop layer 155 so as to cover the lower surface of the etch stop layer 155. The etching stopper layer 155 is not included in the piezoelectric driving part 120. Further, the etching stopper layer 155 may not be necessarily provided. When the etching stopper layer 155 is not provided, a part of the lower electrode layer 150 is formed so as to directly cover the lower portion of the hole 133.

The lower electrode layer 150 is made of a conductive material such as Pt, Ni, or Au. It is desirable that the material of the etching stopper layer 155 be a material that has conductivity and is not etched when the piezoelectric layer is etched. The etching stopper layer 155 is made of Ni, for example.

The intermediate layer 160 is disposed below the piezoelectric layer 130. In this embodiment, the intermediate layer 160 is provided so as to be in contact with each of the lower surface of the lower electrode layer 150 and the lower surface of the piezoelectric layer 130, which is not covered with the lower electrode layer 150. The lower surface of the intermediate layer 160 is flat.

The material of the intermediate layer 160 is not particularly limited as long as it is an insulator. In the present embodiment, the intermediate layer 160 is made of SiO₂And (4) forming. The intermediate layer 160 may be made of an organic material having electrical insulation and heat insulation properties.

The active layer 170 is provided so as to be connected to the entire lower surface of the intermediate layer 160. That is, the active layer 170 is disposed below each of the lower electrode layer 150 and the piezoelectric layer 130.

The active layer 170 is stacked on the upper main surface 111 of the base 110 so as to cover the opening 113. That is, in the present embodiment, the lower surface of the active layer 170 is exposed to the opening 113.

The material constituting the active layer 170 is not particularly limited, and in the present embodiment, the active layer 170 is made of Si.

The piezoelectric device 100 further includes a 1 st external electrode layer 181 and a 2 nd external electrode layer 182. The 1 st external electrode layer 181 is laminated on a partial upper side of the upper electrode layer 140. The 2 nd external electrode layer 182 is laminated on a part of the piezoelectric layer 130 and the upper side of each of the etching stopper layers 155. That is, the 2 nd external electrode layer 182 is stacked on the upper side of the lower electrode layer 150 with the etching stopper layer 155 interposed in the hole 133. Further, a two-layer wiring may be stacked as the lower electrode layer 150. The 1 st external electrode layer 181 and the 2 nd external electrode layer 182 are not included in the piezoelectric driving part 120, respectively.

In this way, the piezoelectric driving unit 120 includes the piezoelectric layer 130, the upper electrode layer 140, the lower electrode layer 150, the intermediate layer 160, and the active layer 170.

As shown in fig. 2, in the piezoelectric driving unit 120, the upper electrode layer 140 is disposed above the piezoelectric layer 130. In the piezoelectric driving unit 120, the lower electrode layer 150 is disposed so as to face at least a part of the upper electrode layer 140 with the piezoelectric layer 130 interposed therebetween.

According to the above configuration, by applying a voltage between the upper electrode layer 140 and the lower electrode layer 150, the piezoelectric driving unit 120 vibrates in vertical bending in accordance with the expansion and contraction of the piezoelectric layer 130.

As shown in fig. 1 and 2, the piezoelectric driving unit 120 is provided with a through groove 121 that penetrates in the vertical direction. The piezoelectric driving unit 120 is provided with a through groove 121 to form a pair of inner side surfaces 122.

As shown in fig. 2, each of the pair of inner surfaces 122 includes a 1 st narrow portion 123 in which the width of the through groove 121 gradually narrows from the upper end surface 131 of the piezoelectric layer 130 toward the lower side. In the present embodiment, a part of the pair of inner surfaces 122 of the piezoelectric layer 130 is formed by the 1 st narrow part 123. Of the pair of inner surfaces 122 of the piezoelectric layer 130, the surface located below the 1 st narrow portion 123 is formed so as to extend in the vertical direction. The 1 st narrow portion 123 may form the entire surface of each of the pair of inner surfaces 122 of the piezoelectric layer 130.

In the present embodiment, the piezoelectric layer 130 has the 1 st corner 134 which is continuous with the upper end surface 131 of the piezoelectric layer 130 and constitutes at least a part of the 1 st narrow part 123. The 1 st corner 134 is convexly curved obliquely upward. In the present embodiment, the 1 st narrow part 123 is entirely constituted by the 1 st corner part 134.

Further, a part of the 1 st narrow part 123 may be constituted by the 1 st corner part 134. In this case, a portion of the 1 st narrow part 123 below the 1 st corner 134 may be an inclined surface.

Further, the inner surface of the hole 133 may be curved in a convex shape obliquely upward at a corner portion which is continuous with the upper end surface 131 of the piezoelectric layer 130 and which constitutes a part of the inner surface of the hole 133.

In the piezoelectric driving unit 120, the upper electrode layer 140 is disposed on the upper end surface 131 of the piezoelectric layer 130. In the present embodiment, the upper end surface 131 of the piezoelectric layer 130 is not exposed as the pair of inner surfaces 122.

In the piezoelectric driving unit 120, the lower electrode layer 150 forms a part of the pair of inner side surfaces 122. The pair of inner surfaces 122 of the lower electrode layer 150 are formed along the vertical direction and are connected to the pair of inner surfaces 122 of the piezoelectric layer 130 continuously in the vertical direction.

In the piezoelectric driving unit 120, the intermediate layer 160 forms a part of the pair of inner side surfaces 122. The pair of inner side surfaces 122 at the intermediate layer 160 is formed along the vertical direction, and is connected to the pair of inner side surfaces 122 at the lower electrode layer 150 so as to be continuous in the vertical direction.

The lower electrode layer 150 may not form a part of the pair of inner side surfaces 122. In this case, the pair of inner surfaces 122 of the piezoelectric layer 130 and the pair of inner surfaces 122 of the intermediate layer 160 are connected to each other continuously in the vertical direction.

As shown in fig. 2, each of the pair of inner side surfaces 122 further includes a 2 nd narrow portion 124 in which the width of the through groove 121 gradually narrows downward from the upper end surface of the active layer 170. In the present embodiment, a part of the pair of inner side surfaces 122 of the active layer 170 is formed by the 2 nd narrow part 124. Of the pair of inner surfaces 122 of the active layer 170, the surface located below the 2 nd narrow portion 124 is formed so as to extend in the vertical direction. The 2 nd narrow portion 124 may constitute the entire surface of the pair of inner side surfaces 122 of the active layer 170.

In the present embodiment, the active layer 170 has a 2 nd corner 172 which is continuous with the upper end surface 171 of the active layer 170 and constitutes at least a part of the 2 nd narrow portion 124. The 2 nd corner 172 is convexly curved obliquely upward. In the present embodiment, the 2 nd narrow part 124 is entirely constituted by the 2 nd corner part 172.

Further, a part of the 2 nd narrow part 124 may be constituted by the 2 nd corner part 172. In this case, a portion of the 2 nd narrow part 124 below the 2 nd corner part 172 may be an inclined surface.

The radius of curvature of the 1 st corner 134 and the radius of curvature of the 2 nd corner 172 are different from each other. In the present embodiment, the radius of curvature of the 1 st corner 134 is larger than the radius of curvature of the 2 nd corner 172. Further, the radius of curvature of the 1 st corner 134 may be smaller than the radius of curvature of the 2 nd corner 172.

In the piezoelectric driving unit 120, the intermediate layer 160 is disposed on the upper end surface 171 of the active layer 170. In the present embodiment, the upper end surface 171 of the active layer 170 is not exposed as the pair of inner side surfaces 122. In other words, in the present embodiment, the upper end surface 171 of the active layer 170 does not constitute the pair of inner side surfaces 122.

The end of the through-groove 121 on the opening 113 side is located on the lower surface of the active layer 170. The width of the through groove 121 is formed to be narrowest at the end on the opening 113 side. As described above, in the present embodiment, the width of the through groove 121 is narrowed in a stepwise manner from the upper end toward the lower end of the through groove 121.

A method for manufacturing a piezoelectric device according to embodiment 1 of the present invention will be described below.

Fig. 3 is a cross-sectional view showing a state where an etching stopper layer is provided on the lower surface of a piezoelectric layer in the method for manufacturing a piezoelectric device according to embodiment 1 of the present invention. As shown in fig. 3, an etching stopper layer 155 is provided on the lower surface of the piezoelectric layer 130 by a lift-off method, a plating method, an etching method, or the like.

Fig. 4 is a cross-sectional view showing a state where a lower electrode layer is provided on the lower surface of each of an etching stopper layer and a piezoelectric layer in the method for manufacturing a piezoelectric device according to embodiment 1 of the present invention. As shown in fig. 4, the lower electrode layer 150 is provided on the entire lower surface of the etching stopper layer 155 and a part of the lower surface of the piezoelectric layer by a peeling method, a plating method, an etching method, or the like.

Fig. 5 is a cross-sectional view showing a state in which an intermediate layer is provided on the lower surface of each of the lower electrode layer and the piezoelectric layer in the method for manufacturing a piezoelectric device according to embodiment 1 of the present invention. As shown in fig. 5, an intermediate layer 160 is provided on the lower surfaces of the lower electrode layer 150 and the piezoelectric layer 130 by cvd (chemical Vapor deposition) method, pvd (physical Vapor deposition) method, or the like.

Fig. 6 is a cross-sectional view showing a state where the lower surface of the intermediate layer is flattened in the method of manufacturing the piezoelectric device according to embodiment 1 of the present invention. As shown in fig. 6, the lower surface of the intermediate layer 160 is planarized by Chemical Mechanical Polishing (CMP) or the like.

Fig. 7 is a cross-sectional view showing a state in which a laminate is bonded to the plurality of layers shown in fig. 6 in the method for manufacturing a piezoelectric device according to embodiment 1 of the present invention. Fig. 8 is a cross-sectional view showing a state in which a laminate is bonded to the lower surface of an intermediate layer in the method for manufacturing a piezoelectric device according to embodiment 1 of the present invention.

As shown in fig. 7 and 8, the laminate 10 is bonded to the lower surface of the intermediate layer 160. The laminate 10 includes a base 110 in which the opening 113 is not formed, and an active layer 170 bonded to the upper surface of the base 110. In the present embodiment, the laminated body 10 is an soi (silicon on insulator) substrate.

Fig. 9 is a cross-sectional view showing a state where the upper surface of the piezoelectric layer is cut in the method of manufacturing the piezoelectric device according to embodiment 1 of the present invention. As shown in fig. 9, the upper surface of the piezoelectric layer 130 is polished by CMP or the like to make the piezoelectric layer 130 have a desired thickness. In this case, the thickness of the piezoelectric layer 130 is adjusted so that a desired amount of expansion and contraction of the piezoelectric layer 130 due to the application of voltage can be obtained.

Fig. 10 is a cross-sectional view showing a state where an upper electrode layer is provided on an upper end surface of a piezoelectric layer in the method for manufacturing a piezoelectric device according to embodiment 1 of the present invention. As shown in fig. 10, an upper electrode layer 140 is provided on a part of the upper end surface 131 of the piezoelectric layer 130 by a lift-off method, a plating method, an etching method, or the like.

Fig. 11 is a cross-sectional view showing a state in which a hole is provided in a piezoelectric layer in the method of manufacturing a piezoelectric device according to embodiment 1 of the present invention. As shown in fig. 11, a hole 133 is formed by etching a part of the piezoelectric layer 130.

Fig. 12 is a cross-sectional view showing a state where the 1 st external electrode layer and the 2 nd external electrode layer are provided in the method of manufacturing a piezoelectric device according to embodiment 1 of the present invention. As shown in fig. 12, the 1 st external electrode layer 181 and the 2 nd external electrode layer 182 are provided by a lift-off method, a plating method, an etching method, or the like.

Fig. 13 is a cross-sectional view showing a state where a recess is provided in a piezoelectric layer to form a through groove in the method for manufacturing a piezoelectric device according to embodiment 1 of the present invention. As shown in fig. 13, a concave portion 121a is provided in the piezoelectric layer 130 by etching a part of the piezoelectric layer 130. The recess 121a corresponds to a part of the through groove 121 of the piezoelectric device 100 of the present embodiment.

After the concave portion 121a is provided in the piezoelectric layer 130, the photoresist applied to the piezoelectric layer 130 and other members for the etching is removed.

In the present embodiment, the recess 121a is provided only in the piezoelectric layer 130 to form the through-groove 121, but the bottom surface of the recess 121a may be located on the lower electrode layer 150, or may be located on the upper side of the lower end surface of the intermediate layer 160 in the intermediate layer 160.

Fig. 14 is an enlarged cross-sectional view showing the vicinity of a concave portion in a state where a photoresist is applied to the upper end surface of a piezoelectric layer in a state where the concave portion is provided in the piezoelectric layer in the method for manufacturing a piezoelectric device according to embodiment 1 of the present invention. As shown in fig. 14, in the method of manufacturing the piezoelectric device 100 according to the present embodiment, the photoresist 1 is provided on at least a portion of the upper end surface 131 of the piezoelectric layer 130 adjacent to the recess 121 a. The photoresist 1 is not provided in the recess 121 a.

As shown in fig. 14, the photoresist 1 has a through groove disposed above the recess 121a so as to be continuous with the recess 121 a. The through-groove of the photoresist 1 has a portion in which the width of the through-groove gradually decreases downward. In other words, the thickness of the photoresist 1 becomes thinner as it approaches the recess 121a in the planar direction of the upper end surface 131 of the piezoelectric layer 130.

In this embodiment, the photoresist 1 is provided with a through groove to form a pair of inner surfaces, and each of the pair of inner surfaces of the photoresist 1 has a portion that is convexly curved obliquely upward.

Next, dry etching is performed with the photoresist 1 provided, thereby further increasing the depth of the recess 121 a. In this dry etching, the outer surface of the photoresist 1 is simultaneously melted. Thus, by melting the photoresist 1, which becomes thinner as it approaches the recess 121a, a portion adjacent to the recess 121a in the upper end surface 131 of the piezoelectric layer 130 starts to be exposed. The upper end surface 131 of the piezoelectric layer 130 is gradually exposed to the outside from the vicinity of the recess 121 a. Thereby, the upper end corner of the recess 121a in the piezoelectric layer 130 is chamfered, and the 1 st corner 134 is formed.

Fig. 15 is a diagram showing a state in which a recess is dug down to the upper end surface of an active layer in the method for manufacturing a piezoelectric device according to embodiment 1 of the present invention. By performing dry etching with the photoresist 1 provided, as shown in fig. 15, the 1 st corner 134 is formed while the recess 121a is dug down until the recess 121a reaches the upper end surface 171 of the active layer 170.

As shown in fig. 14 and 15, since the upper corner of the recess 121a is chamfered as described above, the 1 st corner 134 has an outline similar to the outline of the portion of the photoresist 1 adjacent to the recess 121 a.

Fig. 16 is a cross-sectional view showing a state where a recess is provided in an active layer to form a through groove in the method for manufacturing a piezoelectric device according to embodiment 1 of the present invention. As shown in fig. 16, a recess 121b is provided in the active layer 170 by etching a part of the active layer 170 on an upper end surface 171 of the active layer 170, which is a bottom surface of the recess 121 a. The recess 121b corresponds to a part of the through groove 121 of the piezoelectric device 100 according to embodiment 1 of the present invention.

After the recess 121b is provided in the active layer 170, the resist applied to the active layer 170 and other members for the above-described etching is removed.

In the present embodiment, the recess 121b is provided only in the active layer 170 in order to form the through-groove 121, but the bottom surface of the recess 121b may be located on the upper base 110b or the lower base 110 a.

Fig. 17 is an enlarged cross-sectional view showing the vicinity of the recess in a state where a photoresist is applied to the upper end surface of the active layer in a state where the recess is provided in the active layer in the method for manufacturing a piezoelectric device according to embodiment 1 of the present invention. As shown in fig. 17, in the method of manufacturing the piezoelectric device 100 according to the present embodiment, the photoresist 2 is provided on at least a portion of the upper end surface 171 of the active layer 170 adjacent to the recess 121 b. The photoresist 2 is not provided in the recess 121 b.

As shown in fig. 17, the photoresist 2 has a through groove disposed above the recess 121b so as to be continuous with the recess 121 b. The through-groove of the photoresist 2 has a portion where the width of the through-groove gradually narrows from the side opposite to the active layer 170 side toward the lower side. In other words, the thickness of the photoresist 2 becomes thinner as it approaches the recess 121b in the plane direction of the upper end face 131 of the active layer 170.

In this embodiment, the photoresist 2 is provided with a through groove to form a pair of inner surfaces, and each of the pair of inner surfaces of the photoresist 2 has a portion that is convexly curved obliquely upward.

Next, dry etching is performed with the photoresist 2 provided, thereby further increasing the depth of the recess 121 b. In this dry etching, the outer surface of the photoresist 2 is simultaneously melted. Thus, by melting the photoresist 2 that becomes thinner as it approaches the recess 121b, a portion adjacent to the recess 121b in the upper end surface 171 of the active layer 170 starts to be exposed. The upper end surface 171 of the active layer 170 is gradually exposed to the outside from the vicinity of the recess 121 b. Thereby, the upper end corner of the recess 121b in the active layer 170 is chamfered, forming the 2 nd corner 172.

Fig. 18 is a diagram showing a state in which a recess is dug down to a lower base portion in the method for manufacturing a piezoelectric device according to embodiment 1 of the present invention. By performing dry etching with the photoresist 2 provided, as shown in fig. 18, the 2 nd corner portion 172 is formed while the recess 121b is dug down until the bottom surface of the recess 121b reaches the inside of the lower base 110 a.

As shown in fig. 17 and 18, since the upper corner of the recess 121b is chamfered as described above, the 2 nd corner 172 has an outline similar to the outline of the upper surface of the portion of the photoresist 2 adjacent to the recess 121 b.

Finally, an opening 113 is formed in the base 110 by Deep Reactive Ion Etching (Deep RIE) or the like from the lower main surface 112 side of the base 110 to the base 110. Thus, in the piezoelectric device 100 of the present embodiment, the piezoelectric drive unit 120 is formed. Further, the 1 st external electrode layer 181 and the 2 nd external electrode layer 182 may be provided immediately before the piezoelectric driving part 120 is formed.

The piezoelectric device 100 according to embodiment 1 of the present invention as shown in fig. 2 is manufactured by the above-described steps.

As described above, in the piezoelectric device 100 according to embodiment 1 of the present invention, the piezoelectric driving unit 120 is provided with the through groove 121 penetrating in the vertical direction, thereby forming the pair of inner side surfaces 122. Each of the pair of inner surfaces 122 includes a 1 st narrow portion 123 in which the width of the through groove 121 gradually decreases downward from the upper end surface 131 of the piezoelectric layer 130.

This reduces deformation of the portion of the piezoelectric driving unit 120 facing the through groove 121, thereby suppressing degradation of the electrical characteristics of the piezoelectric device 100.

In the piezoelectric device 100 of the present embodiment, the piezoelectric driving unit 120 is indirectly supported by the base 110, and is located above the base 110 without overlapping the base 110.

Thus, the piezoelectric drive unit 120 can be configured in a thin film structure. Further, the piezoelectric device 100 can be made thin.

In the piezoelectric device 100 of the present embodiment, the piezoelectric layer 130 has the 1 st corner 134 which is continuous with the upper end surface 131 of the piezoelectric layer 130 and constitutes at least part of the 1 st narrow portion 123. The 1 st corner 134 is convexly curved obliquely upward.

This reduces the deformation of the piezoelectric layer 130, which has a large amount of deformation in the portion facing the through groove 121 in the piezoelectric driving unit 120, and suppresses a decrease in the electrical characteristics of the piezoelectric device 100.

In the piezoelectric device 100 of the present embodiment, each of the pair of inner surfaces 122 further includes a 2 nd narrow portion in which the width of the through groove 121 gradually narrows downward from the upper end surface 171 of the active layer 170.

Accordingly, in the portion of the piezoelectric driving unit 120 facing the through groove 121, the deformation can be reduced even below the piezoelectric layer 130, and the deterioration of the electrical characteristics of the piezoelectric device 100 can be suppressed.

In the piezoelectric device 100 of the present embodiment, the active layer 170 has the 2 nd corner 172 which is continuous with the upper end surface 171 of the active layer 170 and constitutes at least a part of the 2 nd narrow portion 124. The 2 nd corner 172 is convexly curved obliquely upward. The radius of curvature of the 1 st corner 134 and the radius of curvature of the 2 nd corner 172 are different from each other.

Thus, the optimal radius of curvature of each corner can be set to alleviate the deformation in each of the piezoelectric layer 130 and the active layer 170.

In the piezoelectric device 100 of the present embodiment, the piezoelectric layer 130 is formed of a single crystal piezoelectric material. The axial direction of the polarization axis of the piezoelectric monocrystal is inclined with respect to the stacking direction of the piezoelectric drive unit 120.

This can reduce the difference in the thermal expansion coefficients of the piezoelectric driving unit 120 in the vertical direction and the planar direction, and thus can suppress a decrease in the electrical characteristics of the piezoelectric device 100.

In the piezoelectric device 100 of the present embodiment, the axial direction of the polarization axis of the single crystal piezoelectric body is not orthogonal to the stacking direction of the piezoelectric driving unit 120.

This can suppress a decrease in the electrical characteristics of the piezoelectric device 100, and can suppress a decrease in the amount of deformation of the piezoelectric driving unit 120 due to voltage application, thereby improving the piezoelectric characteristics of the piezoelectric device 100.

In the piezoelectric device 100 of the present embodiment, the coefficients of thermal expansion of the piezoelectric layers 130 are different from each other in the stacking direction and the planar direction of the piezoelectric driving units 120.

Thus, various materials can be used for the piezoelectric layer 130. In the present embodiment, the pair of inner surfaces 122 includes the 1 st narrow portion 123. Therefore, even if the coefficients of thermal expansion of the piezoelectric layers 130 are different from each other in the two directions, the deformation of the portion facing the through groove 121 in the piezoelectric driving unit 120 can be reduced, and the deterioration of the electrical characteristics of the piezoelectric device 100 can be suppressed.

(embodiment mode 2)

The piezoelectric device of embodiment 2 is explained below. The piezoelectric device according to embodiment 2 of the present invention is different from the piezoelectric device 100 according to embodiment 1 in the configuration of the through-groove and the pair of inner side surfaces. Accordingly, the same structure as that of embodiment 1 of the present invention will not be described repeatedly.

Fig. 19 is a sectional view of a piezoelectric device according to embodiment 2 of the present invention. The sectional view of the piezoelectric device shown in fig. 19 is illustrated in the same sectional view as that of the piezoelectric device 100 shown in fig. 2.

As shown in fig. 19, the piezoelectric layer 130 has a 1 st inclined portion 234 which is continuous with the upper end surface 131 of the piezoelectric layer 130 and constitutes at least a part of the 1 st narrow portion 223. In the present embodiment, the 1 st narrow portion 223 constitutes the entire surface of each of the pair of inner side surfaces 222 in the piezoelectric layer 130. In the present embodiment, the 1 st narrow part 223 is entirely constituted by the 1 st inclined part 234.

Note that a part of the 1 st narrow part 223 may be constituted by the 1 st inclined part 234. In this case, a portion of the 1 st narrow portion 223 below the 1 st inclined portion 234 may be convexly curved obliquely upward.

As shown in fig. 19, the active layer 170 has a 2 nd inclined portion 272 which is continuous with the upper end surface 171 of the active layer 170 and constitutes at least a part of the 2 nd narrow portion 224. In the present embodiment, the 2 nd narrow portion 224 constitutes the entire surface of each of the pair of inner side surfaces 222 at the active layer 170. In the present embodiment, the 2 nd narrow-width portion 224 is entirely constituted by the 2 nd inclined portion 272.

Further, a part of the 2 nd narrow portion 224 may be constituted by the 2 nd inclined portion 272. In this case, a portion of the 2 nd narrow portion 224 below the 2 nd inclined portion 272 may be curved in a convex shape obliquely upward.

A method for manufacturing a piezoelectric device according to embodiment 2 of the present invention will be described below.

Fig. 20 is an enlarged cross-sectional view showing the vicinity of the recessed portion in a state where a photoresist is applied to the upper end surface of the piezoelectric layer in a state where the recessed portion is provided in the piezoelectric layer in the method for manufacturing a piezoelectric device according to embodiment 2 of the present invention. First, similarly to the method for manufacturing the piezoelectric device 100 according to embodiment 1 of the present invention, the concave portion 221a is provided in the piezoelectric layer 130 by etching a part of the piezoelectric layer 130. After the concave portion 221a is provided, the photoresist applied to the piezoelectric layer 130 and other members for the etching is removed. Next, as shown in fig. 20, a photoresist 3 is provided on at least a portion of the upper end surface 131 of the piezoelectric layer 130 adjacent to the recess 221 a. The photoresist 3 is not provided in the recess 221 a.

As shown in fig. 20, the photoresist 3 has a through groove disposed above the recess 221a so as to be continuous with the recess 221 a. The through-groove of the photoresist 3 has a portion in which the width of the through-groove gradually decreases downward. In other words, the thickness of the photoresist 3 becomes thinner as it approaches the concave portion 221a in the plane direction of the upper end surface 131 of the piezoelectric layer 130.

In this embodiment, the photoresist 3 is provided with a through groove to form a pair of inner side surfaces. The pair of inner side surfaces of the photoresist 3 are formed in a planar shape by extending obliquely upward so as to be away from the central axis of the through-groove.

Next, dry etching is performed with the photoresist 3 provided, thereby further increasing the depth of the concave portion 221 a. In this dry etching, the outer surface of the photoresist 3 is simultaneously melted. Similarly to the photoresist 1 of embodiment 1 of the present invention, the photoresist 3 melts, so that the upper corner of the concave portion 221a is chamfered, thereby forming the 1 st inclined portion 234.

Fig. 21 is a diagram showing a state in which a recess is dug down to the upper end surface of an active layer in the method for manufacturing a piezoelectric device according to embodiment 2 of the present invention. By performing dry etching with the photoresist 3 provided, as shown in fig. 21, the 1 st inclined portion 234 is formed while the recess 221a is dug down until the recess 221a reaches the upper end surface 171 of the active layer 170.

As shown in fig. 20 and 21, since the upper end corner of the recess 221a is chamfered as described above, the 1 st inclined portion 234 has an outer shape similar to the outer shape of the portion of the photoresist 3 adjacent to the recess 221 a.

Fig. 22 is a cross-sectional view showing a state where a recess is provided in an active layer to form a through groove in the method for manufacturing a piezoelectric device according to embodiment 2 of the present invention. As shown in fig. 22, a recess 221b is provided in the active layer 170 by etching a part of the active layer 170 on the upper end surface 171 of the active layer 170, which is a bottom surface of the recess 221 a. The recess 221b corresponds to a part of the through groove 221 of the piezoelectric device 100 according to embodiment 2 of the present invention.

After the recess 221b is provided in the active layer 170, the resist applied to the active layer 170 and other members for the above-described etching is removed.

Fig. 23 is an enlarged cross-sectional view showing the vicinity of the recess in a state where a photoresist is applied to the upper end surface of the active layer in a state where the recess is provided in the active layer in the method for manufacturing a piezoelectric device according to embodiment 2 of the present invention. As shown in fig. 23, in the method of manufacturing the piezoelectric device 200 according to the present embodiment, the photoresist 4 is provided on at least a portion of the upper end surface 171 of the active layer 170 adjacent to the recess 221 b. The photoresist 4 is not provided in the recess 221 b.

As shown in fig. 23, the photoresist 4 has a through groove disposed above the recess 221b so as to be continuous with the recess 221 b. The through-groove of the photoresist 4 has a portion in which the width of the through-groove gradually decreases downward. In other words, the thickness of the photoresist 4 becomes thinner as it approaches the recess 221b in the plane direction of the upper end surface 171 of the active layer 170.

In this embodiment, the photoresist 4 is provided with a through groove to form a pair of inner side surfaces. The pair of inner side surfaces of the photoresist 4 are formed in a planar shape by extending obliquely upward in a direction away from the center of the through-groove.

Next, dry etching is performed with the photoresist 4 provided, thereby further increasing the depth of the concave portion 221 b. In this dry etching, the outer surface of the photoresist 4 is simultaneously melted. Similarly to the photoresist 2 of embodiment 1 of the present invention, the upper corner of the concave portion 221b is chamfered by melting the photoresist 4, thereby forming the 2 nd inclined portion 272.

Fig. 24 is a view showing a state in which a recess is dug down to a lower base portion in the method for manufacturing a piezoelectric device according to embodiment 2 of the present invention. By performing dry etching with the photoresist 4 provided, as shown in fig. 24, the 2 nd inclined portion 272 is formed while the concave portion 221b is dug down until the bottom surface of the concave portion 221b reaches the inside of the lower base portion 110 a.

As shown in fig. 23 and 24, since the upper end corner of the recess 221b is chamfered as described above, the 2 nd inclined portion 272 has an outer shape similar to the outer shape of the portion of the photoresist 4 adjacent to the recess 221 b.

Finally, an opening 113 is formed in the base 110 by deep reactive ion etching or the like from the lower main surface 112 side of the base 110 toward the base 110. Thus, in the piezoelectric device 200 of the present embodiment, the piezoelectric drive unit 120 is formed.

The piezoelectric device 200 according to embodiment 2 of the present invention as shown in fig. 19 is manufactured by the above-described steps.

As described above, in the piezoelectric device 200 according to embodiment 2 of the present invention, the piezoelectric layer 130 includes the 1 st inclined portion 234 which is continuous with the upper end surface 131 of the piezoelectric layer 130 and which constitutes at least a part of the 1 st narrow portion 223.

(embodiment mode 3)

A piezoelectric device according to embodiment 3 of the present invention will be described below. The piezoelectric device according to embodiment 3 of the present invention is different from the piezoelectric device 100 according to embodiment 1 mainly in the configuration of each of the piezoelectric driving unit and the base unit. Accordingly, the same structure as that of the piezoelectric device 100 according to embodiment 1 of the present invention will not be described repeatedly.

Fig. 25 is a sectional view of a piezoelectric device according to embodiment 3 of the present invention. The sectional view of the piezoelectric device 300 shown in fig. 25 is illustrated in the same sectional view as the sectional view of the piezoelectric device 100 shown in fig. 2.

As shown in fig. 25, in a piezoelectric device 300 according to embodiment 3 of the present invention, a base portion 310 is formed of one layer. The material constituting the base 310 is not particularly limited. In the present embodiment, the base 310 is made of Si.

As shown in fig. 25, in embodiment 3 of the present invention, the intermediate layer 360 is laminated on the upper main surface 311 of the base 310 so as to cover the upper side of the opening 113. Therefore, in the present embodiment, the lower surface of the intermediate layer 360 is exposed to the opening 113. As described above, in the present embodiment, the plurality of layers constituting the piezoelectric driving unit 120 do not include an active layer.

A method for manufacturing a piezoelectric device according to embodiment 3 of the present invention will be described below.

Fig. 26 is a cross-sectional view showing a state in which an intermediate layer is provided on the lower surface of each of the lower electrode layer and the piezoelectric layer in the method for manufacturing a piezoelectric device according to embodiment 3 of the present invention. First, similarly to the method for manufacturing the piezoelectric device 100 according to embodiment 1 of the present invention, the etching stopper layer 155 and the lower electrode layer 150 are provided below the piezoelectric layer 130. Next, as shown in fig. 26, an intermediate layer 360 is provided on the lower surface of each of the lower electrode layer 150 and the piezoelectric layer 130 by CVD, PVD, or the like.

Fig. 27 is a cross-sectional view showing a state where the lower surface of the intermediate layer is flattened in the method for manufacturing a piezoelectric device according to embodiment 3 of the present invention. As shown in fig. 27, the lower surface of the intermediate layer 360 is planarized by chemical mechanical polishing or the like.

Fig. 28 is a cross-sectional view showing a state where a base portion is bonded to a lower surface of an intermediate layer in the method for manufacturing a piezoelectric device according to embodiment 3 of the present invention. Fig. 29 is a cross-sectional view showing a state after a base portion is bonded to a lower surface of an intermediate layer in the method for manufacturing a piezoelectric device according to embodiment 3 of the present invention.

As shown in fig. 28 and 29, the base 110 is bonded to the lower surface of the intermediate layer 360. At this time, the opening 113 is not formed in the base 110.

Fig. 30 is a cross-sectional view showing a state where the upper surface of the piezoelectric layer is cut in the method for manufacturing a piezoelectric device according to embodiment 3 of the present invention. As shown in fig. 30, the upper surface of the piezoelectric layer 130 is polished by CMP or the like to make the piezoelectric layer 130 have a desired thickness.

Fig. 31 is a cross-sectional view showing a state where an upper electrode layer is provided on an upper end surface of a piezoelectric layer in the method for manufacturing a piezoelectric device according to embodiment 3 of the present invention. As shown in fig. 31, an upper electrode layer 140 is provided on a part of the upper surface of the piezoelectric layer 130 by a lift-off method, a plating method, an etching method, or the like.

Fig. 32 is a cross-sectional view showing a state in which a hole is provided in a piezoelectric layer in the method for manufacturing a piezoelectric device according to embodiment 3 of the present invention. As shown in fig. 32, a hole 133 is formed by etching a part of the piezoelectric layer 130.

Fig. 33 is a cross-sectional view showing a state where the 1 st external electrode layer and the 2 nd external electrode layer are provided in the method of manufacturing a piezoelectric device according to embodiment 3 of the present invention. As shown in fig. 33, the 1 st external electrode layer 181 and the 2 nd external electrode layer 182 are provided by a peeling method, a plating method, an etching method, or the like.

Fig. 34 is a cross-sectional view showing a state where a recess is provided in a piezoelectric layer to form a through groove in the method for manufacturing a piezoelectric device according to embodiment 3 of the present invention. As shown in fig. 34, a concave portion 321a is provided in the piezoelectric layer 130 by etching a part of the piezoelectric layer 130. The recess 321a corresponds to a part of the through groove 321 of the piezoelectric device 300 of the present embodiment.

After the concave portion 321a is provided in the piezoelectric layer 130, the photoresist applied to the piezoelectric layer 130 and other members for the etching is removed.

In the present embodiment, the through-groove 321 is formed so as to penetrate the piezoelectric layer 130 and the lower electrode layer 150, and the recess 121a is provided so that the bottom surface reaches the intermediate layer 360, but the recess 121a may be provided only in the piezoelectric layer 130.

Fig. 35 is an enlarged cross-sectional view showing the vicinity of a concave portion in a state where a photoresist is applied to the upper end surface of a piezoelectric layer in a state where the concave portion is provided in the piezoelectric layer in the method for manufacturing a piezoelectric device according to embodiment 3 of the present invention. As shown in fig. 35, in the method of manufacturing the piezoelectric device 300 according to the present embodiment, the photoresist 5 is provided on at least a portion of the upper end surface 131 of the piezoelectric layer 130 adjacent to the concave portion 321 a. The photoresist 5 is not provided in the recess 321 a.

As shown in fig. 35, the photoresist 5 has a through groove disposed above the recess 321a so as to be continuous with the recess 321 a. The through-groove of the photoresist 5 has a portion in which the width of the through-groove gradually decreases downward. In other words, the photoresist 5 has a thickness that becomes thinner as it approaches the recess 121a in the planar direction of the upper end surface 131 of the piezoelectric layer 130.

In this embodiment, the photoresist 5 is provided with a through groove to form a pair of inner surfaces, and each of the pair of inner surfaces of the photoresist 5 has a portion that is convexly curved obliquely upward.

Next, dry etching is performed with the photoresist 5 provided, thereby further increasing the depth of the concave portion 321 a. In this dry etching, the outer surface of the photoresist 5 is simultaneously melted. Similarly to the photoresist 1 of embodiment 1 of the present invention, the photoresist 5 melts, so that the upper corner of the concave portion 321a in the piezoelectric layer 130 is chamfered, thereby forming the 1 st corner 134.

Fig. 36 is a view showing a state in which a concave portion is dug down to a base portion in the method for manufacturing a piezoelectric device according to embodiment 3 of the present invention. By performing dry etching with the photoresist 5 provided, as shown in fig. 36, the 1 st corner portion 134 is formed while the recess 321a is dug down until the bottom surface of the recess 321a reaches the inside of the base portion 310.

As shown in fig. 35 and 36, since the upper end corner portion of the concave portion 321a is chamfered as described above, the 1 st corner portion 134 has an outer shape similar to the outer shape of the upper surface of the portion of the photoresist 5 adjacent to the concave portion 321 a.

Finally, the opening 113 is formed in the base 310 by deep reactive ion etching or the like from the lower main surface 312 side of the base 310 toward the base 310. Thus, in the piezoelectric device 300 of the present embodiment, the piezoelectric drive unit 120 is formed. Further, the 1 st external electrode layer 181 and the 2 nd external electrode layer 182 may be provided immediately before the piezoelectric driving part 120 is formed.

The piezoelectric device 300 according to embodiment 3 of the present invention as shown in fig. 25 is manufactured by the above-described steps.

As described above, in the piezoelectric device 300 according to embodiment 3 of the present invention, each of the pair of inner surfaces 122 includes the 1 st narrow portion 123 in which the width of the through groove 321 gradually decreases from the upper end surface 131 of the piezoelectric layer 130 toward the lower side. Thus, in the piezoelectric device according to embodiment 3 of the present invention, the deformation of the portion facing the through groove 321 in the piezoelectric driving unit 120 can be reduced, and the deterioration of the electrical characteristics of the piezoelectric device 300 can be suppressed.

In the above-described embodiments, structures that can be combined with each other may be combined as appropriate.

The embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Description of the reference numerals

1. 2, 3, 4, 5, photoresist; 10. a laminate; 100. 200, 300, a piezoelectric device; 110. 310, a base; 110a, a lower base; 110b, an upper base; 111. 311, an upper main surface; 112. 312, a lower main surface; 113. an opening part; 120. a piezoelectric driving section; 121. 221, 321, a through groove; 121a, 121b, 221a, 221b, 321a, recess; 122. 222, an inner lateral surface; 123. 223, 1 st narrow part; 124. 224, 2 nd narrow part; 130. a piezoelectric layer; 131. 171, an upper end surface; 132. a lower end face; 133. a hole portion; 134. the 1 st corner; 140. an upper electrode layer; 150. a lower electrode layer; 155. an etch stop layer; 160. 360, an intermediate layer; 170. an active layer; 172. a 2 nd corner portion; 181. 1 st external electrode layer; 182. 2 nd external electrode layer; 234. 1 st inclined part; 272. the 2 nd inclined part.

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