Manufacturing method for array sensor elements

Abstract

To reduce the mismatch in the crystal structure of the piezoelectric layer that occurs at the end of the first electrode. [Solution] A method for manufacturing an array sensor element includes the steps of (a) forming a first electrode layer on a substrate and patterning the first electrode layer to form a first electrode, (b) forming a piezoelectric layer on the first electrode and patterning the piezoelectric layer to form a piezoelectric element region, and (c) forming a second electrode layer on the piezoelectric element region and patterning the second electrode layer to form a second electrode, wherein in (a), the first electrode layer is patterned such that a tapered shape is formed at the end of the first electrode where the angle between the lower surface of the first electrode and the side surface of the first electrode is less than 90°, and in (b), the piezoelectric layer is patterned such that the piezoelectric element region covers the end of the first electrode.

Description

Technical Field

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[0005]

[0001] The present disclosure relates to a method for manufacturing an array sensor element.

Background Art

[0002] As a detection device in which elements having a structure in which a plurality of thin films are laminated are arranged in an array, for example, an imaging device of Patent Document 1, an ultrasonic device of Patent Document 2, etc. are known. For the formation of the elements used in these detection devices, the manufacturing technology of flat panel displays is utilized. The piezoelectric element of Patent Document 2 includes a lower electrode, a piezoelectric film, and an upper electrode.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above piezoelectric element, when the piezoelectric film is formed covering the end portion of the lower electrode, there is a mismatch between the crystal structure of the piezoelectric film formed on the upper surface of the lower electrode and the crystal structure of the piezoelectric film formed on the side surface of the lower electrode, so there is a risk that the crystallinity of the entire piezoelectric film will decrease.

Means for Solving the Problems

[0005] According to one embodiment of the present disclosure, a method for manufacturing an array sensor element is provided. This manufacturing method includes the steps of (a) forming a first electrode layer on a substrate and patterning the first electrode layer to form a first electrode; (b) forming a piezoelectric layer on the first electrode and patterning the piezoelectric layer to form a piezoelectric element region; and (c) forming a second electrode layer on the piezoelectric element region and patterning the second electrode layer to form a second electrode, wherein in (a), the first electrode layer is patterned such that a tapered shape is formed at the end of the first electrode where the angle between the lower surface of the first electrode and the side surface of the first electrode is less than 90°; and in (b), the piezoelectric layer is patterned such that the piezoelectric element region covers the end of the first electrode. [Brief explanation of the drawing]

[0006] [Figure 1] This is a top view showing the schematic configuration of the array sensor element. [Figure 2] This is a cross-sectional view taken along line II-II, as shown in Figure 1. [Figure 3] This is a cross-sectional view taken along line III-III, as shown in Figure 1. [Figure 4] These are STEM images of Sample 1 and Sample 2. [Figure 5] This is a flowchart showing the manufacturing process of array sensor elements. [Figure 6] This is a diagram to explain step S14. [Modes for carrying out the invention]

[0007] A. Embodiments: A1. Structure of array sensor elements: Figure 1 is a top view showing the schematic configuration of the array sensor element 1. Figure 1 shows arrows representing the mutually orthogonal X, Y, and Z directions. The X and Y directions are parallel to the horizontal plane. The Z direction is parallel to the vertical direction. The X, Y, and Z directions in Figure 1 and the X, Y, and Z directions in other figures point to the same directions. When specifying the direction, the positive direction indicated by the arrow is denoted as "+", and the negative direction opposite to the direction indicated by the arrow is denoted as "-", using both positive and negative signs in the direction notation. The +Z direction is also referred to as "up", and the -Z direction as "down".

[0008] As shown in Figure 1, the array sensor element 1 consists of a substrate 10 and a plurality of sensor elements 2 arranged in an array on the substrate 10. Figure 1 shows an example of an array sensor element 1 having 16 sensor elements 2. In the example shown in Figure 1, each sensor element 2 is arranged in a 4x4 array along the X and Y directions. Note that each sensor element 2 may be arranged in a so-called staggered arrangement, where they are arranged alternately in the X or Y direction. Furthermore, the number of sensor elements 2 in the array sensor element 1 is not limited to 16. In this embodiment, the sensor elements 2 are piezoelectric sensors.

[0009] A silicon wafer or a glass substrate can be used as the substrate 10. The shape of the substrate 10 is a rectangular plate. However, the shape of the substrate 10 may not be a rectangular plate, but a circle, an ellipse, a polygon, or other shapes.

[0010] Figure 2 is a cross-sectional view taken along line II-II in Figure 1. Figure 3 is a cross-sectional view taken along line III-III in Figure 1. As shown in Figure 2, the sensor element 2 comprises a first insulating film 20, a first electrode 31, a piezoelectric element region 41, a second electrode 51, a second insulating film 60, and an upper wiring 71. The first electrode 31, the piezoelectric element region 41, and the second electrode 51 are stacked on the substrate 10 in this order from the -Z direction to the +Z direction. Hereafter, the +Z direction will also be referred to as the stacking direction. Note that the first insulating film 20 and the second insulating film 60 are not shown in Figure 1.

[0011] As shown in Figure 2, a first insulating film 20 is formed on the +Z side of the substrate 10. An insulating film such as a silicon oxide (SiO2) film or a silicon nitride (SiN) film can be used as the first insulating film 20.

[0012] A first electrode 31 and a first electrode wiring 32 are formed on the first insulating film 20. The first electrode 31 and the first electrode wiring 32 are formed in a manufacturing process described later by patterning the first electrode layer 130 after it has been deposited. Here, the first electrode 31 constitutes the sensor element 2 and, in this embodiment, is an electrode used to detect an external force applied to the piezoelectric element region 41. On the other hand, the first electrode wiring 32 is wiring used, for example, to electrically connect multiple first electrodes 31 to each other.

[0013] As shown in Figures 1 and 2, the first electrodes 31 of the multiple sensor elements 2 arranged in the Y direction are not electrically connected to each other. On the other hand, as shown in Figures 1 and 3, the first electrodes 31 of the multiple sensor elements 2 arranged in the X direction are electrically connected to each other by the first electrode wiring 32.

[0014] In a plan view of the substrate 10, the shape of the first electrode 31 is circular, as viewed along a direction perpendicular to the substrate 10. As shown in Figure 3, among the multiple first electrodes 31 arranged in the X direction, the ends of the first electrodes 31 closest to the edge of the substrate 10 are connected to the first electrode wiring 32. This first electrode wiring 32 extends toward the edge of the substrate 10 and functions as a terminal for electrical connection to external devices. Also, as shown in Figure 1, a rectangular first electrode wiring 32 is formed between each of the two sensor elements 2 at both ends of the multiple sensor elements 2 arranged in the Y direction and the edge of the substrate 10. This first electrode wiring 32 also functions as a terminal for electrical connection to external devices.

[0015] In this embodiment, the first electrode 31 and the first electrode wiring 32 are laminated films in which titanium (Ti), an aluminum-copper alloy (AlCu), and titanium are laminated in this order.

[0016] As shown in an enlarged view in FIG. 2, the first electrode 31 has a lower surface 31a, a side surface 31b, and an upper surface 31c. The lower surface 31a is a surface that contacts the first insulating film 20, which is the lower layer. The upper surface 31c is a surface opposite to the lower surface 31a. The side surface 31b is a surface that connects the lower surface 31a and the upper surface 31c.

[0017] At the end of the first electrode 31, a tapered shape is formed where the angle θ formed by the lower surface 31a and the side surface 31b is smaller than 90°. In this embodiment, the angle θ formed by the lower surface 31a and the side surface 31b is 53° or less. As will be described in detail later, when the angle θ is smaller than 90°, the crystallinity of the entire piezoelectric element region 41 can be enhanced. It is preferable to set the angle θ to 53° or less because the crystallinity of the entire piezoelectric element region 41 can be further enhanced.

[0018] As shown in FIG. 2, a piezoelectric element region 41 is formed on the first electrode 31. Also, a piezoelectric dummy region 42 is formed on the first insulating film 20 or on the first electrode wiring 32. The piezoelectric element region 41 and the piezoelectric dummy region 42 are formed by patterning the piezoelectric layer 140 after the piezoelectric layer 140 is formed in the manufacturing process. Here, the piezoelectric element region 41 constitutes the sensor element 2 and is a region for detecting an external force applied in this embodiment. On the other hand, the piezoelectric dummy region 42 is a region formed for reducing the unevenness of the film height or reducing the unevenness of etching in patterning.

[0019] In this embodiment, the material of the piezoelectric layer 140 is aluminum nitride (AlN). As another embodiment, as the material of the piezoelectric layer 140, metal compounds other than aluminum nitride, or composite oxides such as lead zirconate titanate (PZT) can be used. [[ID=...]]

[0020] [[ID=...]] The piezoelectric layer 140 is formed, for example, by being oriented such that the axis of spontaneous polarization in the crystal structure is along the Z direction. Thereby, the sensor element 2 having good piezoelectric characteristics can be formed. It is preferable that the first electrode 31 is selected from a material having a crystal structure such that the orientation of the piezoelectric element region 41 is in a desired direction. Specifically, it is preferable that the first electrode 31 is made of a material having the same or a similar crystal structure as the crystal structure of the piezoelectric layer 140. In the manufacturing process, since the piezoelectric layer 140 is formed on the first electrode 31, the orientation of the piezoelectric layer 140 is affected by the crystal structure of the first electrode 31. Therefore, by using a material having the same or a similar crystal structure as the crystal structure of the piezoelectric layer 140 for the material of the first electrode 31 under the piezoelectric layer 140, the piezoelectric layer 140 can be oriented in a desired direction. Note that the relationship between the axis of spontaneous polarization in the crystal structure of the piezoelectric layer 140 and the film surface direction of the piezoelectric layer 140 is not limited to the above. Regardless of the relationship between the axis of spontaneous polarization in the crystal structure of the piezoelectric layer 140 and the film surface direction of the piezoelectric layer 140, the piezoelectric characteristics of the piezoelectric layer 140 can be improved by improving the orientation of the piezoelectric layer 140.

[0021] In the present embodiment, the uppermost layer of the first electrode 31 is a titanium layer, and the piezoelectric element region 41 is aluminum nitride. The crystal structure of titanium is a hexagonal close-packed structure. The crystal structure of aluminum nitride is a wurtzite-type structure of the hexagonal system. Since the crystal structure of the uppermost layer of the first electrode 31 and the crystal structure of the piezoelectric element region 41 are similar, the orientation of the piezoelectric element region 41 can be improved.

[0022] As shown in FIG. 1, the shape of the piezoelectric element region 41 in plan view is circular. As shown in FIG. 2, the piezoelectric element region 41 is formed so as to cover the end portion of the first electrode 31. Thereby, the volume of the piezoelectric element region 41 contributing to pressure detection can be increased.

[0023] As shown in FIG. 2, the second electrode 51 is formed on the piezoelectric element region 41. The second electrode 51 is formed by patterning the second electrode layer 150 after the second electrode layer 150 is formed in the manufacturing process.

[0024] As shown in Figure 1, the shape of the second electrode 51 in plan view is circular. As shown in Figure 2, in plan view, the second electrode 51 is formed inside the first electrode 31. Specifically, in plan view, the lower surface of the second electrode 51 is formed inside the upper surface 31c of the first electrode 31. This allows the region on the first electrode 31, which is a region of the piezoelectric element region 41 with high crystallinity and orientation, to be used as a pressure-detecting sensor element 2.

[0025] In this embodiment, the second electrode 51 is a laminated film in which titanium, an aluminum-copper alloy, and titanium are stacked in that order. Preferably, the second electrode 51 is formed such that its sheet resistance is equal to that of the first electrode 31. This makes it possible to reduce the periodic difference in the detection signal output from the sensor element 2 when the voltage applied between the first electrode 31 and the second electrode 51 is controlled to periodically reverse.

[0026] As shown in Figure 2, a second insulating film 60 is formed on the second electrode 51, the piezoelectric element region 41, the piezoelectric dummy region 42, and the first insulating film 20. The second insulating film 60 is not formed on some of the first electrode wiring 32 that functions as terminals, and on some of the second electrode 51. For example, silicon oxide or silicon nitride can be used as the second insulating film 60.

[0027] An upper wiring 71 is formed on the second electrode 51, the first electrode wiring 32, the piezoelectric dummy region 42, and the second insulating film 60. The upper wiring 71 is formed in the manufacturing process by patterning the upper wiring layer 170 after it has been deposited. As shown in Figures 1 and 2, the upper wiring 71 covers the end of the second insulating film 60 on the second electrode 51 and is formed to electrically connect two adjacent second electrodes 51 aligned in the Y direction. The upper wiring 71 is also formed to electrically connect the end second electrode 51 among a plurality of second electrodes 51 aligned in the Y direction to the first electrode wiring 32 which functions as a terminal. In this embodiment, the material of the upper wiring 71 is an aluminum-copper alloy.

[0028] As described above, the piezoelectric element region 41 is formed to cover the end of the first electrode 31. The inventors have found that if the angle θ between the lower surface 31a and the side surface 31b is large, an inconsistency occurs between the crystal structure of the piezoelectric element region 41 on the side surface 31b and the crystal structure of the piezoelectric element region 41 on the upper surface 31c, resulting in a decrease in the overall crystallinity and orientation of the piezoelectric element region 41. An inconsistency between the crystal structure of the piezoelectric element region 41 on the side surface 31b and the crystal structure of the piezoelectric element region 41 on the upper surface 31c is undesirable because it leads to stress-induced deterioration of the piezoelectric element region 41 and a decrease in the piezoelectric performance of the sensor element 2. Therefore, in this embodiment, the angle θ is formed to be 53° or less. This improves the overall crystallinity and orientation of the piezoelectric element region 41.

[0029] Figure 4 shows the STEM (Scanning Transmission Electron Microscope) images of Sample 1 and Sample 2, respectively. Sample 1 is a sample with an angle θ of 68°. Sample 2 is a sample with an angle θ of 53°.

[0030] Note that since Sample 1 and Sample 2 were fabricated for the purpose of investigating the angle θ, the material of the first insulating film 20, the film structure of the first electrode 31, and the material of the piezoelectric element region 41 differ from those of the embodiment. The material of the first insulating film 20 in Sample 1 and Sample 2 is silicon nitride. The first electrode 31 in Sample 1 and Sample 2 is a laminated film in which aluminum-copper alloy and titanium are stacked in that order. The material of the piezoelectric element region 41 in Sample 1 and Sample 2 is aluminum nitride.

[0031] As shown in Figure 4, in sample 1, where the angle θ is large, a crack can be seen in the piezoelectric element region 41 at the boundary between the piezoelectric element region 41 on the side surface 31b of the first electrode 31 and the piezoelectric element region 41 on the upper surface 31c of the first electrode 31. On the other hand, in sample 2, the degree of cracking is improved compared to sample 1. From these results, it can be seen that by setting the angle θ to 53° or less, a piezoelectric element region 41 with good crystallinity can be manufactured. The reason why cracks occur when the angle θ is close to 90° is thought to be that there are areas where crystal initiation points cannot be created during the deposition of the piezoelectric layer 140.

[0032] The above results are independent of the materials of the first electrode 31 and the piezoelectric element region 41. The larger the angle θ, the more likely it is that a mismatch will occur between the crystal structure of the piezoelectric element region 41 on the side surface 31b of the first electrode 31 and the crystal structure of the piezoelectric element region 41 on the upper surface 31c of the first electrode 31. Therefore, regardless of the materials of the first electrode 31 and the piezoelectric element region 41, by setting the angle θ to 53° or less, a piezoelectric element region 41 with good crystallinity can be manufactured.

[0033] A2. Manufacturing process for array sensor elements: Figure 5 is a flowchart showing the manufacturing process for realizing the manufacturing method of the array sensor element 1. Figure 6 is a diagram illustrating step S14. In the manufacturing process in this disclosure, in step S14, which is the process of forming the first electrode 31, measures are taken to form it so that the angle θ is 53° or less.

[0034] As shown in Figure 5, in step S10, the first insulating film 20 is deposited on the substrate 10 by thermal oxidation or CVD (Chemical Vapor Deposition).

[0035] In step S12, the first electrode layer 130 is formed by sputtering. In step S14, the first electrode 31 and the first electrode wiring 32 are formed. Specifically, first, a resist mask 200 shown in Figure 6 is formed on the first electrode layer 130. More specifically, after photoresist is applied, the resist mask 200 is formed by exposure and development to create a desired pattern. Subsequently, the first electrode layer 130 is etched by plasma dry etching to form the first electrode 31 and the first electrode wiring 32.

[0036] The gas used in dry etching is a mixture of oxygen and chlorine gas. The oxygen gas etches the resist. As shown in Figure 6, the first electrode layer 130 is mainly etched by the chlorine gas, and the resist mask 200 is also mainly etched by the oxygen gas. As a result, the resist edge 201, which is the edge of the resist mask 200 that is in contact with the upper surface of the first electrode layer 130, recedes inward towards the inside of the resist mask 200 as etching progresses. This makes it possible to form a first electrode 31 with a relatively small angle θ.

[0037] In step S16 of Figure 5, a piezoelectric layer 140 is deposited by sputtering so as to cover the first electrode 31 and the first electrode wiring 32. In step S18, the piezoelectric layer 140 is patterned using photolithography to form a piezoelectric element region 41 and a piezoelectric dummy region 42. Dry etching using a gas containing chlorine gas is used for etching the piezoelectric layer 140.

[0038] Furthermore, if the piezoelectric layer 140 is made of PZT, the piezoelectric layer 140 is deposited using, for example, the sol-gel method.

[0039] In step S20, a second electrode layer 150 is deposited by sputtering so as to cover the piezoelectric element region 41 and the piezoelectric dummy region 42. In step S22, the second electrode 51 is formed by patterning the second electrode layer 150 using photolithography. Dry etching is used for etching the second electrode layer 150. In step S22, the second electrode layer 150 is patterned so that, in a plan view, the lower surface of the second electrode 51 is inside the upper surface 31c of the first electrode layer 130.

[0040] Furthermore, within the piezoelectric element region 41, the piezoelectric element region 41 on the upper surface 31c of the first electrode 31 has higher crystallinity than other regions. Therefore, in the second electrode layer 150, the second electrode layer 150 formed on the piezoelectric element region 41 on the upper surface 31c of the first electrode 31 is easier to deposit thickly due to the high crystallinity of the underlying layer. Consequently, by using the second electrode layer 150 formed on the piezoelectric element region 41 on the upper surface 31c of the first electrode 31 as the second electrode 51, a second electrode 51 with low sheet resistance can be fabricated. As a result, an array sensor element 1 with good response speed can be fabricated.

[0041] In step S24, a second insulating film 60 is deposited using the CVD method so as to cover the second electrode 51. In step S26, the second insulating film 60 is patterned using photolithography. Dry etching is used for etching the second insulating film 60.

[0042] In step S28, the upper wiring layer 170 is deposited using sputtering so as to cover the second insulating film 60. In step S30, the upper wiring 71 is formed by patterning the upper wiring layer 170 using photolithography. Dry etching or wet etching is used for etching the upper wiring layer 170. In the case of dry etching, a fluorine-based gas containing fluorine gas is used. In the case of wet etching, a fluorine-based chemical solution containing fluorine is used.

[0043] In step S32, a mounting process is performed in which the first electrode wiring 32, which functions as a terminal, is electrically connected to the external device. Specifically, in the mounting process, for example, if the connection between the substrate 10 and the external device is performed using a printed circuit board, the terminals formed on the substrate 10 and the terminals formed on the printed circuit board are electrically connected using the wire bonding method. For example, if the connection between the substrate 10 and the external device is performed using a flexible printed circuit board (FPC), the terminals formed on the substrate 10 and the terminals formed on the flexible circuit board are joined. As a result of step S32, the array sensor element 1 and the external device are electrically connected. After step S32 is completed, this manufacturing process is finished.

[0044] According to the embodiment described above, the manufacturing process of the array sensor element 1 includes steps S12 to S22. Steps S12 and S14 are steps of forming a first electrode layer 130 on a substrate 10 and patterning the first electrode layer 130 to form a first electrode 31. Steps S16 and S18 are steps of forming a piezoelectric layer 140 on the first electrode 31 and patterning the piezoelectric layer 140 to form a piezoelectric element region 41. Steps S20 and S22 are steps of forming a second electrode layer 150 on the piezoelectric element region 41 and patterning the second electrode layer 150 to form a second electrode 51. In step 14, the first electrode layer 130 is patterned such that a tapered shape is formed at the end of the first electrode 31, where the angle θ between the lower surface 31a and the side surface 31b of the first electrode 31 is less than 90°. In step 18, the piezoelectric layer 140 is patterned such that the piezoelectric element region 41 covers the end of the first electrode 31. This makes it less likely for inconsistencies to occur between the crystal structure of the piezoelectric element region 41 on the side surface 31b and the crystal structure of the piezoelectric element region 41 on the top surface 31c, thus enabling the fabrication of a piezoelectric element region 41 with high overall crystallinity and orientation. Therefore, degradation of the piezoelectric element region 41 due to stress is suppressed, and the decrease in the piezoelectric performance of the sensor element 2 is suppressed. Furthermore, in this embodiment, since the angle θ is 53° or less, the overall crystallinity and orientation of the piezoelectric element region 41 can be further improved.

[0045] Furthermore, in step S14, the first electrode layer 130 is patterned using plasma-type dry etching with a gas containing chlorine gas and oxygen gas. This allows the end of the first electrode 31 to be processed into a tapered shape with a relatively small angle θ.

[0046] Furthermore, in step S26, the second electrode layer 150 is patterned such that, in a plan view, the lower surface of the second electrode 51 is inside the upper surface 31c of the first electrode layer 130. This allows the region on the first electrode 31, which is a region of the piezoelectric element region 41 with high crystallinity and orientation, to be used as a pressure detection region.

[0047] B. Other embodiments: (B1) In the above embodiment, the first electrode 31 and the second electrode 51 have a laminated structure of Ti layer, AlCu layer, and Ti layer, and the material of the piezoelectric element region 41 is AlN. The materials of the first electrode 31, the piezoelectric element region 41, and the second electrode 51 are not limited to these. Furthermore, the film deposition method and etching method in each step of the manufacturing process of the array sensor element 1 are not limited to the above. For example, the etching method of the first electrode layer 130 in step S14 is not limited to plasma dry etching.

[0048] (B2) In the above embodiment, in step S22, the second electrode layer 150 is patterned such that, in plan view, the lower surface of the second electrode 51 is inside the upper surface 31c of the first electrode layer 130. In another embodiment, in step S22, the second electrode layer 150 may be patterned such that, in plan view, the lower surface of the second electrode 51 includes the upper surface 31c of the first electrode layer 130. This makes it possible to increase the volume of the piezoelectric element region 41 that detects voltage.

[0049] C. Other forms: This disclosure is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit. For example, this disclosure can also be implemented in the following forms. The technical features in the embodiments described below that correspond to the technical features in each of the forms described below can be replaced or combined as appropriate in order to solve some or all of the problems of this disclosure, or to achieve some or all of the effects of this disclosure. Furthermore, if such technical features are not described as essential in this specification, they can be deleted as appropriate.

[0050] (1) According to a first embodiment of the present disclosure, a method for manufacturing an array sensor element is provided. This manufacturing method includes the steps of (a) forming a first electrode layer on a substrate and patterning the first electrode layer to form a first electrode; (b) forming a piezoelectric layer on the first electrode and patterning the piezoelectric layer to form a piezoelectric element region; and (c) forming a second electrode layer on the piezoelectric element region and patterning the second electrode layer to form a second electrode, wherein in (a), the first electrode layer is patterned such that a tapered shape is formed at the end of the first electrode where the angle between the lower surface of the first electrode and the side surface of the first electrode is less than 90°, and in (b), the piezoelectric layer is patterned such that the piezoelectric element region covers the end of the first electrode. According to this embodiment, inconsistencies are less likely to occur between the crystal structure of the piezoelectric element region on the side surface and the crystal structure of the piezoelectric element region on the upper surface, so that a piezoelectric element region with high crystallinity and orientation of the entire piezoelectric element region can be manufactured. Therefore, degradation due to stress in the piezoelectric element region can be suppressed, and the decrease in the piezoelectric performance of the sensor element can be suppressed.

[0051] (2) In the above embodiment, the angle may be 53° or less. This embodiment can further improve the crystallinity and orientation of the entire piezoelectric element region.

[0052] (3) In the above embodiment (a), the first electrode layer may be patterned using plasma dry etching with a gas containing chlorine gas and oxygen gas. According to this embodiment, the end of the first electrode can be processed into a tapered shape with a relatively small angle.

[0053] (4) In the above embodiment (c), the second electrode layer may be patterned such that, in a plan view along a direction perpendicular to the surface of the substrate, the lower surface of the second electrode is inside the upper surface of the first electrode layer. According to this embodiment, the region on the first electrode, which is a region of the piezoelectric element region with high crystallinity and orientation, can be used as a region for detecting pressure. [Explanation of symbols]

[0054] 1…Array sensor element, 2…Sensor element, 10…Substrate, 20…First insulating film, 31…First electrode, 31a…Bottom surface, 31b…Side surface, 31c…Top surface, 32…First electrode wiring, 41…Piezoelectric element region, 42…Piezoelectric dummy region, 51…Second electrode, 60…Second insulating film, 71…Upper wiring, 130…First electrode layer, 140…Piezoelectric layer, 150…Second electrode layer, 170…Upper wiring layer, 200…Resist mask, 201…Resist edge

Claims

1. A method for manufacturing an array sensor element, (a) A step of forming a first electrode by depositing a first electrode layer on a substrate and patterning the first electrode layer, (b) A step of forming a piezoelectric layer on the first electrode and patterning the piezoelectric layer to form a piezoelectric element region, (c) The process includes the steps of forming a second electrode layer on the piezoelectric element region and patterning the second electrode layer to form a second electrode, In (a) above, the first electrode layer is patterned such that a tapered shape is formed at the end of the first electrode, where the angle between the lower surface of the first electrode and the side surface of the first electrode is less than 90°. In (b) above, the piezoelectric layer is patterned such that the piezoelectric element region covers the end of the first electrode. A method for manufacturing array sensor elements.

2. A method for manufacturing an array sensor element according to claim 1, The angle is 53° or less. A method for manufacturing array sensor elements.

3. A method for manufacturing an array sensor element according to claim 1, In (a) above, the first electrode layer is patterned using a plasma-type dry etching method that uses a gas containing chlorine gas and oxygen gas. A method for manufacturing array sensor elements.

4. A method for manufacturing an array sensor element according to claim 1, In (c) above, the second electrode layer is patterned such that, in a plan view along a direction perpendicular to the surface of the substrate, the lower surface of the second electrode is inside the upper surface of the first electrode layer. A method for manufacturing array sensor elements.

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