JP6056905B2 - Piezoelectric element, piezoelectric sensor, and electronic device - Google Patents

Description

The present invention also relates piezoelectric element piezoelectric body is formed on the thin film, the piezoelectric sensor comprising a piezoelectric element, and electronic equipment.

  2. Description of the Related Art Conventionally, a piezoelectric element (ultrasonic element) that outputs a supersonic wave by vibrating a support film by laminating a piezoelectric body on a support film and applying a voltage to the piezoelectric body to vibrate is known (for example, , See Patent Document 1).

  The ultrasonic element of Patent Document 1 includes a piezoelectric vibrator in which a piezoelectric thin film is sandwiched between electrode metal films on a membrane. Such an ultrasonic element vibrates the piezoelectric thin film by applying a voltage to the upper and lower electrode metal films, and the membrane on which the piezoelectric thin film is formed also vibrates and outputs ultrasonic waves.

JP 2006-229901 A

By the way, when manufacturing an ultrasonic element as described in Patent Document 1, generally, a lower electrode metal film is formed on a membrane, a piezoelectric thin film is formed on the upper layer, and then this piezoelectric thin film is etched. By doing so, it is patterned into a predetermined shape. The same applies to the formation of the upper electrode metal layer. An electrode metal layer is formed on the lower electrode metal film or the piezoelectric thin film, and this electrode metal layer is etched to be patterned into a predetermined shape.
However, in the method of repeating etching as described above, even when the piezoelectric thin film is etched and when the upper electrode metal layer is etched, even the lower electrode metal layer is etched (overetching), and the lower layer metal layer is etched. The film thickness dimension of the electrode metal film is reduced. As described above, when the thickness of the electrode metal film is reduced, the electrical resistance is increased. For example, the power consumption is increased, the sound pressure of the output ultrasonic wave is reduced, or the control in the high frequency range is performed. The problem that becomes difficult arises.

The present invention is, in view of the problems as described above, can reduce the piezoelectric element the electrical resistance of the electrode, and an object thereof is to provide a piezoelectric sensor, and electronic equipment.

The piezoelectric element according to the related art of the present invention includes a support having a displacement portion that is displaceable along a thickness direction, and a plan view of the support body viewed from the thickness direction of the displacement portion on the support. The lower electrode main body provided in the inner region of the outer peripheral edge of the displacement portion, and the lower electrode line portion connected to the lower electrode main body portion and extending from the inner region of the outer peripheral edge of the displacement portion to the outer region A lower electrode layer having a first piezoelectric layer provided on the lower electrode main body in an inner region of an outer peripheral edge of the displacement portion in the plan view, and an outer side of the displacement portion in the plan view. An upper electrode layer that extends from the inner region to the outer region of the periphery and is at least partially laminated on the first piezoelectric layer and is insulated from the lower electrode layer, and on the support, the lower electrode line portion At least partly covered Characterized by comprising a piezoelectric layer.
Note that the support having a displacement of portions, for example, to form openings such as through-holes or recesses in the substrate, by forming the supporting film so as to close the opening, the support film on the opening The structure used as the displacement part which can be displaced along a film | membrane thickness direction can be illustrated. Furthermore, it is good also as a structure by which a displacement part is hold | maintained through the bridge | bridging part in the above opening parts formed in the board | substrate. Furthermore, for example, a concave groove may be formed in the support, and the bottom of the concave groove may be a displacement portion that can be displaced along the thickness direction. Furthermore, it is good also as a structure which forms the opening part, such as a through-hole or a ditch | groove, in a board | substrate, joins the elastic member which has elasticity larger than a board | substrate, and is flexible, and an elastic member displaces to this opening part. .
Further, the displacement portion is configured such that the entire circumference of the outer peripheral edge is held by the main body portion of the support body, or the outer peripheral edge is held at equal intervals so that the displacement amount of the center point is maximized. Alternatively, the other end portion may be held by the main body portion of the support so that the displacement amount of the one end portion of the displacement portion is maximized.

In this related technology , the first piezoelectric layer is laminated on the lower electrode body portion of the lower electrode layer, and the second piezoelectric layer is laminated on at least a part of the lower electrode line portion of the lower electrode layer. As a result, the lower electrode layer is covered and protected by the first piezoelectric layer and the second piezoelectric layer, so that the lower electrode layer is over-etched when forming the piezoelectric layer and the upper electrode layer of the piezoelectric element. Therefore, an increase in the electric resistance of the lower electrode layer can be suppressed, and a piezoelectric element having a low electric resistance can be provided. In such a low electric resistance piezoelectric element, when a voltage is applied between the lower electrode layer and the upper electrode layer to vibrate the displacement part, vibration with a large amplitude can be obtained with low power, thereby promoting energy saving. Can be made. Even when the displacement amount of the support film is detected by the current value output from the first piezoelectric layer, since the electric resistance of the lower electrode line portion is small, the loss of the current output from the first piezoelectric layer is reduced. The displacement of the support film can be detected with high accuracy.

  In addition, in consideration of the over-etching of the lower electrode layer as described above, it may be possible to preliminarily form the thickness dimension of the lower electrode layer, but in this case, over-etching is not applied in the portion where the piezoelectric film is laminated, There is a problem that the thickness dimension of the lower electrode layer increases and the total thickness dimension of the laminated portion of the piezoelectric film and the upper electrode layer also increases. On the other hand, in the present invention, the thickness dimension of the lower electrode layer can be set without expecting an increase in electrical resistance due to over-etching of the lower electrode layer and variations in film thickness, and the piezoelectric element can be made thinner.

  Further, it is possible to form a second piezoelectric layer made of the same material as the first piezoelectric layer on the lower electrode line portion. In this case, the second piezoelectric layer is formed simultaneously with the first piezoelectric layer. be able to. Therefore, compared to a case where a protective layer or the like for protecting the lower electrode line portion is separately used, the piezoelectric element can be easily manufactured and the manufacturing cost can be reduced.

The piezoelectric element of the present invention includes a support having a displacement portion that is displaceable along the thickness direction, and a plan view of the support on the support viewed from the thickness direction of the displacement portion . the first electrode body portion provided in the inner region of the periphery, and is connected to the first electrode body portion and the first electrode lines provided from the inner region of the outer peripheral edge of the front Symbol displacement portion over the outer region a first electrode layer having a section in the plan view, the inside area of the outer peripheral edge of the displacement portion, a first piezoelectric layer provided on the first electrode main part on, in the plan view, at least some Ri is a Do heavy the first piezoelectric layer, the second electrode body portion provided in the inner area of the outer peripheral edge of the displacement portion, and is connected to the second electrode body portion and the front Symbol displacement unit second electrode line portion provided across the outer region from the inner region of the outer peripheral edge of the A second electrode layer which chromatic, on the support, in the plan view, in a position that does not cover the outer peripheral edge of the displacement portion is provided along the first electrode line portion, the first electrode line A second piezoelectric layer covering at least a portion of the first electrode line portion, and at least a portion of the second electrode line portion on the second piezoelectric layer in the plan view. It is provided along the intersecting direction.
In the present invention, the first piezoelectric layer is laminated on the first electrode body portion of the first electrode layer, and the second piezoelectric layer is provided along the first electrode line portion of the first electrode layer. Covers the part. Accordingly, the first electrode layer is covered and protected by the first piezoelectric layer or the second piezoelectric layer, so that the first electrode layer can be formed when the piezoelectric layer or the second electrode layer of the piezoelectric element is formed. However, over-etching does not occur, an increase in the electrical resistance of the first electrode layer can be suppressed, and a piezoelectric element having a low electrical resistance can be provided. In such a low electric resistance piezoelectric element, when a voltage is applied between the first electrode layer and the second electrode layer to vibrate the displacement portion, vibration with a large amplitude can be obtained with low power, thereby saving energy. Can be promoted. Even when the displacement of the support film is detected by the current value output from the first piezoelectric layer, the loss of the current output from the first piezoelectric layer is low because the electrical resistance of the first electrode wire portion is small. The displacement of the support film can be detected with high accuracy.
In consideration of overetching of the first electrode layer as described above, it may be possible to increase the thickness of the first electrode layer in advance, but in this case, overetching is not applied in the portion where the piezoelectric film is laminated. Therefore, there is a problem that the thickness dimension of the first electrode layer increases and the total thickness dimension of the laminated portion of the piezoelectric film and the second electrode layer also increases. On the other hand, in the present invention, the film thickness dimension of the first electrode layer can be set without expecting an increase in electrical resistance due to overetching of the first electrode layer and variations in film thickness, and the piezoelectric element can be made thin. it can.
It is also possible to form a second piezoelectric layer made of the same material as the first piezoelectric layer on the first electrode line portion. In this case, the second piezoelectric layer is formed simultaneously with the first piezoelectric layer. can do. Therefore, compared to a case where a protective layer or the like for protecting the first electrode line portion is separately used, the piezoelectric element can be easily manufactured and the manufacturing cost can be reduced.
Further, by forming the second electrode line portion on the second piezoelectric layer, the first electrode line portion and the second electrode line portion can be crossed without separately forming an insulating layer.

In the piezoelectric element of the present invention, the first electrode main body portion and the second electrode main body portion are located in an inner region of the outer peripheral edge of the displacement portion in the plan view, and the first electrode wire portion and the second electrode The line portion is located from the inner region to the outer region of the outer peripheral edge of the displacement portion in the plan view, and the second piezoelectric layer is in a position not overlapping the outer periphery of the displacement portion in the plan view. characterized by the provided configuration.
When the displacement part is displaced in conjunction with the vibration of the first piezoelectric layer, or when the displacement part is displaced by an external stress, the displacement is formed by reducing the film thickness dimension of the edge part of the displacement part. The amount of displacement of the part can be increased. Here, in the present invention, since the second piezoelectric layer is provided at a position that does not overlap the edge of the displacement portion, the thickness dimension in the vicinity of the edge of the displacement portion does not increase. Therefore, even when the displacement portion is displaced by the vibration of the first piezoelectric layer, the displacement amount can be increased both when the displacement portion is displaced by an external force. For this reason, for example, when the ultrasonic wave is output by vibrating the displacement portion, the amplitude of the displacement portion is increased with low power compared to, for example, the case where the second piezoelectric layer is also laminated on the edge of the displacement portion. It is possible to output an ultrasonic wave having a larger sound pressure. In the case of receiving ultrasonic waves, the displacement portion can be greatly vibrated by the received ultrasonic waves, so that the reception sensitivity can be improved and the ultrasonic waves can be detected with high accuracy.

The piezoelectric element of the present invention may have a configuration in which a wiring layer is provided on the second piezoelectric layer.
In the present invention, the wiring layer is formed on the piezoelectric element, whereby the wiring layer and the first electrode layer can be separated.
In addition, when a plurality of wiring patterns are formed on a single flat substrate, the line width of each wiring pattern is restricted depending on the size of the substrate and the electrical resistance may increase. On the other hand, in the present invention, by forming the wiring layer also on the second piezoelectric layer, the wiring pattern can be formed in a two-stage configuration on the substrate and the second piezoelectric layer. Therefore, compared with the case where a plurality of wiring patterns are formed on one substrate, the size of the substrate can be reduced, and an increase in electrical resistance can be prevented.

The wiring layer may be configured to be electrically connected between two different points of the first electrode line portion.

In the present invention, the wiring layer connects two different points of the first electrode layer. Thus, between these two points of the first electrode layer, a current is applied to the first electrode layer and the wiring layer, it is possible to further reduce the electrical resistance.

In the piezoelectric element of the present invention, the first electrode line portion extends from the inner region to the outer region of the outer peripheral edge of the displacement portion in the plan view, and an element connection line connected to the first electrode main body portion, A first electrode wiring that is continuous with the element connection line, is provided in an outer region of an outer peripheral edge of the displacement portion, and has a line width smaller than a line width of the element connection line in the plan view, The two piezoelectric layers are preferably provided so as to cover the first electrode wiring.

In this invention, the 2nd piezoelectric material layer has covered the 1st electrode wiring with a small line width among the 1st electrode wire parts.
Since the electrical resistance of the first electrode line portion decreases as the line width dimension increases, it is preferable to increase the line width of the first electrode line portion. However, when the piezoelectric element is actually arranged on the substrate, the line width of the first electrode wiring cannot be sufficiently secured due to the relationship between other elements and their wiring patterns, and may be smaller than the element connection line. . In such a case, if the first electrode wiring is over-etched during patterning of the piezoelectric layer and the second electrode, the resistance of the first electrode wiring becomes higher. On the other hand, in this invention, the 2nd piezoelectric material layer is laminated | stacked on the 1st electrode wiring in which such a line | wire width becomes small. For this reason, when the piezoelectric layer and the second electrode are patterned, the first electrode wiring is not over-etched, and an increase in electrical resistance can be prevented.

The piezoelectric sensor according to the present invention includes a support having a displacement portion that is displaceable along a thickness direction, and a plan view of the support on the support viewed from the thickness direction of the displacement portion . the first electrode body portion provided in the inner region of the periphery, and is connected to the first electrode body portion and the first electrode lines provided from the inner region of the outer peripheral edge of the front Symbol displacement portion over the outer region a first electrode layer having a section in the plan view, the inside area of the outer peripheral edge of the displacement portion, a first piezoelectric layer provided on the first electrode main part on, in the plan view, at least some Ri is a Do heavy the first piezoelectric layer, the second electrode body portion provided in the inner area of the outer peripheral edge of the displacement portion, and is connected to the second electrode body portion and the front Symbol displacement unit second electrode provided over the outer region from the inner region of the outer peripheral edge of the A second electrode layer to have a part, on the support, in the plan view, in a position that does not cover the outer peripheral edge of the displacement portion is provided along the first electrode line portion, the first A second piezoelectric layer covering at least a portion of the electrode wire portion, and at least a portion of the second electrode wire portion on the second piezoelectric layer in the plan view. A plurality of piezoelectric elements are provided along a direction intersecting the portion, and the plurality of piezoelectric elements are arranged in an array.

In the present invention, the piezoelectric sensor includes a plurality of piezoelectric elements arranged in an array. Here, each of the piezoelectric elements, as described above, since a part of the first electrode layer is covered by the second piezoelectric layer, it is possible to suppress the increase in electrical resistance due to over-etching. Therefore, for example, when outputting ultrasonic waves by vibrating the support film, it is possible to output ultrasonic waves with low power consumption and high sound pressure (large amplitude). When detecting a signal, a large electrical signal (current value) can be output, and the detection accuracy can be improved.
Further, in such a piezoelectric sensor, a first electrode line portion connected to each piezoelectric element is required. When a small piezoelectric sensor is formed, the line width of each first electrode line portion is also regulated and becomes small. In such a case, the electrical resistance of the first electrode line portion is also increased. Here, if the top of the first electrode line portion is not the second piezoelectric layer is formed, there is a possibility that the first electrode line portion is further electrical resistance increases by being over-etched. On the other hand, in the present invention, the resistance at the time of patterning of the piezoelectric layer and the second electrode layer is formed by forming the second piezoelectric layer even for the first electrode line portion having such a small line width. An increase can be prevented.

The electronic device according to the present invention includes a support having a displacement portion that is displaceable along a thickness direction, and a plan view of the support on the support viewed from the thickness direction of the displacement portion . the first electrode body portion provided in the inner region of the periphery, and is connected to the first electrode body portion and the first electrode lines provided from the inner region of the outer peripheral edge of the front Symbol displacement portion over the outer region a first electrode layer having a section in the plan view, the inside area of the outer peripheral edge of the displacement portion, a first piezoelectric layer provided on the first electrode main part on, in the plan view, at least some Ri is a Do heavy the first piezoelectric layer, the second electrode body portion provided in the inner area of the outer peripheral edge of the displacement portion, and is connected to the second electrode body portion and the front Symbol displacement unit second electrode line portion provided across the outer region from the inner region of the outer peripheral edge of the And a second electrodes layer Yes, on the support, in the plan view, in a position that does not cover the outer peripheral edge of the displacement portion is provided along the first electrode line portion, the first electrode line A second piezoelectric layer covering at least a portion of the first electrode line portion, and at least a portion of the second electrode line portion on the second piezoelectric layer in the plan view. A piezoelectric element provided along the intersecting direction is provided.
In the present invention, as described above, the piezoelectric element provided in the electronic device has a part of the first electrode layer covered with the second piezoelectric layer, and can suppress an increase in electric resistance due to over-etching, thereby reducing power consumption. Thus, it is possible to drive the displacement portion, to suppress the loss of the electric signal from the displacement portion, and to reduce the thickness of the piezoelectric element. Therefore, even in an electrical device including such a piezoelectric element or a piezoelectric sensor incorporating the above-described piezoelectric element, the displacement portion can be driven with low power, or the loss of an electrical signal can be suppressed. Electricity can be achieved. In addition, since the piezoelectric element can be reduced in thickness, it is possible to promote downsizing of the electric device.

A method of manufacturing a thin film piezoelectric body according to a related art of the present invention includes a support having a displacement portion that is displaceable in a thickness direction, and a plan view of the support body viewed from the thickness direction of the displacement portion on the support. A lower electrode body portion provided in an inner region of an outer peripheral edge of the displacement portion, and a lower electrode connected to the lower electrode body portion and extending from an inner region of the outer periphery of the displacement portion to an outer region. A lower electrode layer having a line portion; a first piezoelectric layer provided on the lower electrode main body portion in an inner region of an outer peripheral edge of the displacement portion in the plan view; and the displacement portion in the plan view. An upper electrode layer that extends from the inner region to the outer region of the outer peripheral edge of the outer peripheral edge and is at least partially laminated on the first piezoelectric layer and is insulated from the lower electrode layer, and the lower electrode line on the support. Provided to cover at least part of the part A second piezoelectric layer comprising: a lower electrode patterning step of patterning the lower electrode layer on the support; and the first electrode on the lower electrode layer. A piezoelectric layer laminating step of laminating the piezoelectric layer including the piezoelectric layer and the second piezoelectric layer, and performing an etching process outside the formation region of the first piezoelectric layer and the second piezoelectric layer. A piezoelectric layer patterning step for forming the first piezoelectric layer and the second piezoelectric layer, an upper electrode stacking step for stacking the upper electrode layer, and an upper electrode patterning for etching and patterning the upper electrode layer And a process.

In this related technique , after the lower electrode patterning step, a second piezoelectric layer that covers at least a part of the lower electrode wiring portion of the lower electrode layer, and a first piezoelectric layer stacked on the lower electrode main body portion of the lower electrode layer A piezoelectric layer laminating step for laminating piezoelectric layers for forming the body layer is performed. Then, after the piezoelectric layer stacking step, the piezoelectric layer is etched by the piezoelectric layer patterning step to cover at least a part of the first piezoelectric layer on the lower electrode main body portion and the lower electrode wiring portion. Forming a second piezoelectric layer; In addition, after the piezoelectric layer patterning step, the upper electrode layering step and the upper electrode patterning step are performed to form the upper electrode layer while suppressing an increase in electric resistance of the lower electrode layer.
By manufacturing the piezoelectric element by such a manufacturing method, it is possible to suppress an increase in the electric resistance of the lower electrode layer as in the above-described invention. In addition, since the first piezoelectric layer and the second piezoelectric layer can be formed at the same time, the manufacturing process is simplified compared to a method of separately forming a protective film for protecting the lower electrode layer, for example. it can.

1 is a plan view of a piezoelectric element according to a first embodiment of the present invention. It is sectional drawing of the piezoelectric element of 1st embodiment. It is sectional drawing which shows a part of manufacturing process of a piezoelectric element. It is sectional drawing which shows the remaining one part of the manufacturing process of a piezoelectric element. It is sectional drawing of the piezoelectric element of 2nd embodiment which concerns on this invention. In the piezoelectric element of the modification of 2nd embodiment, it is the top view which looked at a part of lower electrode wire part from the thickness direction of the board | substrate. It is sectional drawing in the AA line in FIG. It is a cross-sectional part in the BB line in FIG. It is a figure which shows the piezoelectric element of 3rd embodiment which concerns on this invention, (A) is a top view, (B) is sectional drawing. It is a top view which shows a part of ultrasonic sensor of 4th embodiment which concerns on this invention. It is a perspective view which shows typically the structure of PDA of 5th embodiment. It is a perspective view which shows typically the structure of the ultrasonic sensor with which PDA is provided.

[First embodiment]
Hereinafter, the structure of the piezoelectric element according to the first embodiment of the present invention will be described with reference to the drawings.

[Configuration of piezoelectric element]
FIG. 1 is a plan view of the piezoelectric element of the first embodiment.
FIG. 2 is a cross-sectional view of the piezoelectric element of the first embodiment.
In FIG. 1, the piezoelectric element 10 includes a substrate 11 in which an opening 111 is formed, a support film 12 formed on the substrate 11 so as to straddle the inside and outside of the opening 111, and a lower portion formed on the support film 12. The electrode layer 20, the first piezoelectric layer 30 formed inside the opening 111, the second piezoelectric layer 40 formed outside the opening 111, and the inside and outside of the opening 111 are formed. And an upper electrode layer 50. Here, the substrate 11 and the support film 12 make up the support of the present invention, and the support film 12 forms the displacement part of the present invention with the membrane 121 that is a region that closes the opening 111. .
In this embodiment, an example is shown in which the support film 12 is formed on the substrate 11 having the opening 111 that is a through-hole to form the support having the membrane 121 that is a displacement portion. For example, the opening 111 may be a concave groove, and the support film 12 may be configured to close the opening of the opening 111 of the concave groove. Moreover, the support body which formed the ditch | groove in the board | substrate 11 and made the bottom part the displacement part may be sufficient.
Further, an example in which the support is formed of the substrate 11 and the support film 12 is shown, but another layer such as an insulating film is provided on the support film 12 and the lower electrode layer 20 is provided on the other layer. It is good also as a structure.
As the piezoelectric element 10, for example, by applying a voltage to the first piezoelectric layer 30, the support film 12 is vibrated, and an ultrasonic transmission element that outputs ultrasonic waves is received by the support film 12. An ultrasonic receiving element that outputs an electrical signal corresponding to vibration from the first piezoelectric layer 30; a stress detecting element that detects stress applied to the support film 12 based on the electrical signal output from the first piezoelectric layer 30; It can be used as a driving force generating element that drives the first piezoelectric layer 30 and applies a driving force to an object in contact with the support film 12. In the present embodiment, an example in which the piezoelectric element 10 functions as an ultrasonic transmission element will be described as an example.

The substrate 11 is formed of a semiconductor forming material such as silicon (Si) that can be easily processed by etching or the like. Further, the opening 111 formed in the substrate 11 is preferably formed in a circular shape in plan view. Thereby, in the membrane 121 which is the support film 12 inside the opening 111, the stress with respect to the bending of the membrane 121 can be made uniform.
That is, for example, when the opening 111 is formed in a rectangular shape, for example, and the first piezoelectric layer 30 is formed in the center of the rectangle, the support is provided even at a position where the distance from the center point of the membrane 121 is the same. An area where the film 12 is easily bent and an area where the film 12 is difficult to be bent are generated. In contrast, when the circular opening 111 is formed as in this embodiment, the distance from the center point of the membrane to the edge 111A of the opening 111 (which constitutes the outer peripheral edge of the displacement portion in the present invention). Since the distance from the center point of the membrane 121 is the same, the ease of bending of the support film 12 is equal and the membrane 121 can be bent evenly.

The support film 12 is formed on the substrate 11 so as to close the opening 111. The support film 12 has a two-layer structure of, for example, a SiO ₂ film and a ZrO ₂ layer. Here, when the substrate 11 is a Si substrate, the SiO ₂ layer can be formed by thermally oxidizing the surface of the substrate. The ZrO ₂ layer is formed on the SiO ₂ layer by a technique such as sputtering. Here, the ZrO ₂ layer is a layer for preventing Pb constituting PZT from diffusing into the SiO ₂ layer when, for example, PZT is used as the first piezoelectric layer 30 or the second piezoelectric layer 40. . Further, the ZrO ₂ layer has an effect of improving the bending efficiency with respect to the distortion of the piezoelectric film 131.

  The lower electrode layer 20 is formed inside the opening 111 in a plan view, and is continuous with the lower electrode main body 21 in which the first piezoelectric layer 30 is laminated on the upper layer, and the lower electrode main body 21. A lower electrode line portion 22 that is formed across the inside and outside of the region surrounded by the edge portion 111 </ b> A of 111, and the first piezoelectric layer 30 is not stacked, and a lower electrode terminal that is formed at the tip of the lower electrode line portion 22 Part 23. That is, the lower electrode line portion 22 is formed from the inner region to the outer region of the edge portion 111 </ b> A on the membrane 121.

The first piezoelectric layer 30 is laminated on the lower electrode main body 21 of the lower electrode layer 20. The first piezoelectric layer 30 is formed, for example, by forming PZT (lead zirconate titanate) into a film shape. In the present embodiment, PZT is used as the first piezoelectric layer 30. However, any material may be used as long as the material can be contracted in the in-plane direction by applying a voltage. Lead titanate (PbTiO ₃ ), lead zirconate (PbZrO ₃ ), lead lanthanum titanate ((Pb, La) TiO ₃ ), or the like may be used.
The first piezoelectric layer 30 expands and contracts in the in-plane direction when a voltage is applied to the lower electrode main body 21 and an upper electrode layer 50 described later. At this time, one surface of the first piezoelectric layer 30 is joined to the support film 12 via the lower electrode main body portion 21, but the upper electrode layer 50 is formed on the other surface, but this upper portion Since no other layers are laminated on the electrode layer 50, the support film 12 side of the first piezoelectric layer 30 is difficult to expand and contract, and the upper electrode layer 50 side is easily expanded and contracted. For this reason, when a voltage is applied to the first piezoelectric layer 30, a convex bend is generated on the opening 111 side, and the membrane 121 is bent. Therefore, by applying an AC voltage to the first piezoelectric layer 30, the membrane 121 vibrates in the film thickness direction, and ultrasonic waves are output from the opening 111 due to the vibration of the membrane 121.

The upper electrode layer 50 is partially laminated on the first piezoelectric layer 30 and is patterned at an arrangement position that is insulated from the lower electrode layer 20 in plan view. Specifically, the upper electrode layer 50 is continuous with the upper electrode main body portion 51 laminated on the first piezoelectric layer 30 and the upper electrode main body portion 51 and extends in a direction different from the lower electrode line portion 22. The upper electrode line part 52 formed over the inside and outside of the opening 111 in plan view, and the upper electrode terminal part 53 formed at the tip of the upper electrode line part are provided.
Here, a region of the first piezoelectric layer 30 that overlaps both the upper electrode layer 50 and the lower electrode main body 21 is a region that is contracted when a voltage is applied.

  The second piezoelectric layer 40 is made of PZT, which is the same material as the first piezoelectric layer 30. The second piezoelectric layer 40 is formed outside the opening 111 of the support film 12 and covers the lower electrode line portion 22 of the lower electrode layer 20. Specifically, the second piezoelectric layer 40 has an end position 22 </ b> A that is separated from the edge 111 </ b> A of the opening 111 on the support film 12 by a predetermined dimension that does not affect the bending of the membrane 121 in the lower electrode line portion 22. And between the connecting portion 22B of the lower electrode terminal portion 23 and the lower electrode line portion 22. This is because when the second piezoelectric layer 40 is formed so as to overlap the edge 111A of the opening 111, the rigidity against the bending of the membrane 121 is increased, and the output ultrasonic wave has a low sound pressure. More preferably, the second piezoelectric layer 40 is connected to the connecting portion 22B from the end position 22A where the distance L from the edge 111A of the opening 111 satisfies the following formula (1) where the thickness dimension of the support film 12 is t. It is preferable to be formed on the lower electrode line part 22 up to.

[Equation 1]
L> 5t (1)

This is because when the membrane 121 of the support film 12 bends, a moment force is generated in the support film 12 so as to enter the opening 111, and this moment force causes the edge of the opening 111 in plan view. The supporting membrane within a distance range of 111A to 5t receives a tensile force. Therefore, when the second piezoelectric layer 40 is formed within this distance range, resistance is generated when the membrane 121 is bent, and the sound pressure of the ultrasonic wave is reduced. On the other hand, at a distance of 5 t or more from the edge 111A of the opening 111 in plan view, the above-described influence does not work and the membrane 121 can be favorably bent. On the other hand, if the formation position of the end portion of the second piezoelectric layer 40 is too far from the opening 111, the exposed area of the lower electrode line portion 22 increases, so that the patterning of the first and second piezoelectric layers 30, 40 is performed. At the time of patterning the upper electrode layer 50, the exposed portion of the lower electrode line portion 22 may be over-etched to increase the electrical resistance. Therefore, the position where the second piezoelectric layer 40 is formed is most preferably a position covering from the position separated from the edge 111A of the opening 111 by 5t to the connecting portion 22B of the lower electrode terminal portion 23 and the lower electrode line portion 22. .
In addition, since the wiring for applying a voltage to the 1st piezoelectric material layer 30 is connected to the lower electrode terminal part 23, the 2nd piezoelectric material layer 40 is not formed.

[Piezoelectric element manufacturing method]
Next, a method for manufacturing the piezoelectric element as described above will be described with reference to the drawings.
3 and 4 are cross-sectional views showing the manufacturing process of the piezoelectric element.
In order to manufacture the piezoelectric element 10, first, as shown in FIG. 3A, the substrate 11 (Si) is thermally oxidized to form a SiO ₂ layer on the surface of the substrate 11. Further, a Zr layer is formed on the SiO ₂ layer by sputtering, and the ZrO ₂ layer is formed by oxidizing the Zr layer. Thereby, for example, the support film 12 having a thickness of 3 μm is formed.

Thereafter, the lower electrode layer 20 is formed on one surface side of the substrate 11 by, for example, sputtering. The material of the lower electrode layer 20 is not particularly limited as long as it is a conductive film. In the present embodiment, a Ti / Ir / Pt / Ti laminated structure film is used. The lower electrode layer 20 is uniformly formed so as to have a film thickness of 2 μm.
Then, a resist is formed on the lower electrode layer 20 at positions where the lower electrode main body portion 21 and the lower electrode line portion 22 are formed by using, for example, a photolithography method. Next, the region of the lower electrode layer where the resist is not formed is removed by etching and patterned, and the lower electrode main body portion 21, the lower electrode line portion 22, and the lower electrode terminal portion 23 are formed as shown in FIG. Form (lower electrode patterning step).

Thereafter, as shown in FIG. 3C, a piezoelectric layer 60 made of PZT is formed on one side of the substrate 11 on which the lower electrode layer 20 is patterned. In forming the piezoelectric layer 60, a MOD (Metal Organic Decomposition) method is used to form a 12-layer film with a total thickness of 1.4 μm, for example (piezoelectric layer stacking step).
Then, a resist is formed on the piezoelectric layer 60 at the positions where the first piezoelectric layer 30 and the second piezoelectric layer 40 are formed using, for example, a photolithography method, and a region where the resist is not formed is removed by etching. Pattern. As a result, as shown in FIG. 3D, the first piezoelectric layer 30 is formed on the lower electrode body portion 21 and the second piezoelectric layer 40 is formed on the lower electrode line portion 22 (piezoelectric layer). Patterning step).
In this piezoelectric layer patterning step, in the region where the first piezoelectric layer 30 and the second piezoelectric layer 40 are formed, the lower electrode layer 20 is not etched, so that there is no inconvenience such as a decrease in electrical resistance.
The distance L from the lower electrode line portion 22 formed in the region where the first piezoelectric layer 30 on the opening 111 is not provided and the edge 111A of the opening 111 is 5t (in this embodiment, t = Since it is 3 μm, the lower electrode line portion 22 in the range of L = 15 μm may be over-etched when the piezoelectric layer 60 is etched, but in a very small range with respect to the entire lower electrode line portion 22. Therefore, even if the electrical resistance of this portion increases, it is not affected.

Thereafter, as shown in FIG. 4A, the upper electrode layer 50 is uniformly formed on one surface of the substrate 11 by, for example, sputtering. In the conductive film for forming the upper electrode layer 50, any material having conductivity may be used as in the lower electrode layer 20, but in this embodiment, an Ir film is used, and the thickness dimension is, for example, It is formed to be 50 nm (upper electrode lamination step).
Then, a resist for patterning the upper electrode body 51, the upper electrode line portion 52, and the upper electrode terminal portion 53 is formed on the upper electrode layer 50 by using, for example, a photolithography method, and the resist is not formed. Is removed by etching and patterned. Thereby, the upper electrode layer 50 is patterned as shown in FIG. 4B (upper electrode patterning step).
Also in the upper electrode patterning step, since the lower electrode layer 20 is covered with the first piezoelectric layer 30 and the second piezoelectric layer 40 as in the piezoelectric layer patterning step, overetching of the lower electrode layer 20 is performed. Is prevented, and an increase in electrical resistance of the lower electrode layer 20 can be suppressed.

  Next, the thickness dimension of the substrate 11 is adjusted. For this purpose, as shown in FIG. 4C, the substrate on the side opposite to the one surface on which the lower electrode layer 20, the first piezoelectric layer 30, the second piezoelectric layer 40, and the upper electrode layer 50 are formed. The other surface (surface from which ultrasonic waves are output) 11 is subjected to processing such as cutting and polishing. By performing such cutting and polishing, the etching amount when forming the opening 111 can be reduced. Here, the opening 111 is formed by RIE (Reactive Ion Etching) using an ICP (Inductive Coupled Plasma) etching apparatus. However, the depth of etching, rigidity against film stress warpage, and strength against handling are taken into consideration. Then, it is preferable to perform cutting and grinding so that the thickness dimension of the substrate 11 is 200 μm.

In the formation of the opening 111, a resist is formed at a position other than the position where the opening 111 on the other surface side of the substrate 11 is formed. This resist is formed to a thickness of, for example, about 10 μm so as to withstand the etching of the substrate 11. Thereafter, as shown in FIG. 4D, the substrate 11 is etched from the other surface side to the SiO ₂ layer of the support film 12 using an ICP etching apparatus.
Thus, the piezoelectric element 10 is manufactured.

[Operational effects of the first embodiment]
As described above, the piezoelectric element according to the first embodiment includes the first electrode on the lower electrode body 21 formed inside the opening 111 in the lower electrode layer 20 formed across the opening 111. The piezoelectric layer 30 is formed, and the second piezoelectric layer 40 is formed on the lower electrode line portion 22 outside the opening 111 in the lower electrode line portion 22.
For this reason, when the piezoelectric layer 60 is etched to form the first piezoelectric layer 30 and the second piezoelectric layer 40, it is possible to suppress the disadvantage that the lower electrode layer is overetched and the electrical resistance increases. For this reason, the amount of expansion and contraction of the first piezoelectric layer 30 can be increased with low power, and the ultrasonic wave output by the vibration of the membrane 121 can also be set to a high sound pressure.
Further, it is not necessary to increase the thickness dimension of the lower electrode layer 20 in consideration of over-etching, and the thickness dimension of the lower electrode layer 20 can be reduced. Therefore, the piezoelectric element 10 itself can also be thinned.
Furthermore, the first piezoelectric layer 30 and the second piezoelectric layer 40 are made of PZT, which is the same material. That is, the first piezoelectric layer 30 and the second piezoelectric layer 40 can be formed simultaneously by the piezoelectric layer stacking step and the piezoelectric layer patterning step. Thereby, compared with the case where another protective film is provided on the lower electrode layer 20, for example, the manufacturing process can be simplified, and the configuration can be simplified without the need for separately providing the protective film.

The second piezoelectric layer 40 is formed at a position that does not overlap the edge 111 </ b> A of the opening 111 in plan view.
For this reason, since the second piezoelectric layer 40 does not provide resistance when the membrane 121 is bent, the amplitude of the membrane 121 is larger than when the second piezoelectric layer 40 is formed on the edge 111A of the opening 111. It can be vibrated with. Therefore, even when the voltage applied to the first piezoelectric layer 30 is a low voltage, an ultrasonic wave with a high sound pressure can be output.

Further, the second piezoelectric layer 40 is formed from the end portion 22A of the lower electrode line portion 22 that is separated from the edge portion 111A of the opening 111 by a distance L that is five times the thickness t of the support film 12. The electrode line portion 22 and the lower electrode terminal portion 23 are formed to cover up to the connection portion 22B.
When the membrane 121 is bent, the support film 12 receives a moment force in the direction of entering the opening 111, so that the support film 12 near the edge 111 </ b> A of the opening 111 has a tensile force acting on the opening 111 side. Expand and contract. Here, when the second piezoelectric layer 40 is formed in the vicinity of the edge of the opening 111, the expansion and contraction of the support film 12 is restricted, so that the amount of bending of the membrane 121 may be limited. . On the other hand, as described above, by forming the second piezoelectric layer 40 at a position away from the edge 111A of the opening 111 by the distance L, the bending resistance of the membrane 121 does not increase, and the membrane 121 The amount of deflection does not decrease. Therefore, compared with the case where the distance from the edge 111A of the opening 111 to the position where the second piezoelectric layer 40 is formed is less than the distance L, it is possible to output a high sound pressure ultrasonic wave.

[Second Embodiment]
Next, a piezoelectric element according to a second embodiment of the present invention will be described with reference to the drawings.
FIG. 5 is a cross-sectional view of the piezoelectric element according to the second embodiment of the present invention.
In the piezoelectric element 10A of the second embodiment, the auxiliary electrode layer 70 that is a wiring layer is formed on the second piezoelectric layer 40 of the piezoelectric element 10 of the first embodiment.
Specifically, the auxiliary electrode layer 70 is formed on the upper layer of the second piezoelectric layer 40 from the connection portion 22B of the lower electrode layer 20, and again at the end position 22A of the second piezoelectric layer 40. Connected to.

Such an auxiliary electrode layer 70 is formed of the same material as that of the upper electrode layer 50, and is formed simultaneously with the upper electrode layer 50 in the upper electrode patterning step.
That is, after forming a conductive film as shown in FIG. 4A in the upper electrode stacking step, in the upper electrode pattern forming step, the upper electrode layer 50 and the auxiliary electrode layer 70 are formed respectively. A resist is formed. Then, by removing the conductive film other than the resist formation region by etching, an auxiliary electrode layer 70 as shown in FIG. 5 is formed.

[Operational effects of the second embodiment]
In the piezoelectric element 10A of the second embodiment, the same effects as the piezoelectric element 10 of the first embodiment can be obtained, the increase in the electric resistance of the lower electrode layer 20 is suppressed, and the piezoelectric element 10A itself can be made thin. Can promote.
Furthermore, by providing the auxiliary electrode layer 70, the electrical resistance can be further reduced in the wiring portion from the lower electrode terminal portion 23 to the lower electrode main body portion 21, and the first piezoelectric layer 30 can be formed with lower power. It can be driven to output ultrasonic waves.

Further, in the piezoelectric element 10A of FIG. 5, the configuration in which the end portion of the auxiliary electrode layer 70 is located outside the edge portion 111A of the opening 111 is not limited to this, and for example, the second piezoelectric layer 40 is used. The auxiliary electrode layer 70 may also be formed on the lower electrode line portion 22 from the end position 22A to the first piezoelectric layer 30. As described above, the upper electrode layer 50 is a layer having a thickness dimension of, for example, 50 nm and a thickness sufficiently smaller than that of the second piezoelectric layer 40, and is formed simultaneously with the upper electrode layer 50. The auxiliary electrode layer 70 is also formed with the same thickness as the upper electrode layer 50. Therefore, even if such an auxiliary electrode layer 70 is formed so as to straddle the inside and outside of the opening 111, the influence on the bending of the membrane is so small as to be negligible and does not cause a reduction in the sound pressure of the ultrasonic waves. When the auxiliary electrode layer 70 is formed on the lower electrode line portion 22 from the end position 22A of the second piezoelectric layer 40 to the first piezoelectric layer 30 as described above, the piezoelectric layer patterning process or the upper portion is performed. In the electrode patterning step, the auxiliary electrode stacked on the lower electrode line portion 22 even when the lower electrode line portion 22 from the end position 22A of the second piezoelectric layer 40 to the first piezoelectric layer 30 is over-etched. The layer 70 can suppress an increase in electrical resistance. Therefore, an increase in electrical resistance can be prevented more effectively, and an ultrasonic wave with a high sound pressure can be output at a low voltage.
Similarly, the auxiliary electrode layer 70 may be formed on the lower electrode terminal portion 23. In this case, an increase in electrical resistance in the lower electrode terminal portion 23 can be prevented.

[Modification of Second Embodiment]
In the second embodiment described above, the auxiliary electrode layer 70 that connects two points of the lower electrode layer 20 (between the end position 22A and the connection portion 22B) is exemplified as the wiring layer, but the present invention is not limited to this. 7 and FIG. 8 may be adopted.
FIG. 6 is a plan view of a part of the lower electrode line portion 22 of the piezoelectric element, which is a modification of the second embodiment, as viewed from the thickness direction of the substrate 11. 7 is a cross-sectional view taken along line AA in FIG. 8 is a cross-sectional view taken along line BB in FIG.

In this piezoelectric element, a second piezoelectric layer 40 </ b> A smaller than the width dimension of the lower electrode line portion 22 is provided on the lower electrode line portion 22. As shown in FIGS. 6 and 7, an auxiliary electrode layer 70 </ b> A as a wiring layer covering the second piezoelectric layer 40 </ b> A is provided on the lower electrode line portion 22.
Accordingly, as shown in FIG. 8, the auxiliary electrode layer 70A is in contact with the lower electrode line portion 22 also at the outer peripheral edge of the second piezoelectric layer 40A. As a result, the auxiliary electrode layer 70A and the lower electrode line portion 22 form a tube-like wiring structure with the second piezoelectric layer 40A provided at the center, thereby further reducing the electrical resistance in the lower electrode line portion 22. Is possible.

[Third embodiment]
Next, a piezoelectric element according to a third embodiment of the present invention will be described with reference to the drawings.
FIG. 9 is a diagram illustrating the piezoelectric element of the third embodiment, where (A) is a plan view and (B) is a cross-sectional view.
In the piezoelectric element 10A of the second embodiment, the example in which the auxiliary electrode layer 70 connected to the lower electrode layer 20 is provided on the second piezoelectric layer 40 is shown, but the piezoelectric element 10B of the third embodiment is The upper electrode line portion 52 is formed in the upper layer of the second piezoelectric layer 40.

In the piezoelectric element 10B of the third embodiment as described above, a wiring pattern in which the lower electrode layer 20 and the upper electrode layer 50 are crossed with a simple configuration by causing the second piezoelectric layer 40 to function as an insulating layer. Can be formed.
That is, when the piezoelectric element 10B is formed in, for example, an array, the lower electrode line portion 22 and the upper electrode line portion 52 are formed to cross each other due to the arrangement relationship of the elements on the array substrate. There is. In such a case, conventionally, in order to prevent the contact between the lower electrode line portion 22 and the upper electrode line portion 52, it has been necessary to separately form an insulating layer. On the other hand, in the piezoelectric element 10B of the third embodiment, the upper electrode line portion 52 and the lower electrode line are formed without forming an insulating layer separately by forming the upper electrode line portion 52 in the second piezoelectric layer 40. The part 22 can be crossed.

[Fourth embodiment]
Next, as a fourth embodiment of the present invention, an ultrasonic sensor provided with the piezoelectric element as described above will be described with reference to the drawings.
FIG. 10 is a plan view showing a part of the ultrasonic sensor according to the fourth embodiment.
In FIG. 10, an ultrasonic sensor 1 is a piezoelectric sensor of the present invention, and has an array structure in which a plurality of piezoelectric elements 10 are arranged in a lattice shape.
Such an ultrasonic sensor 1 can focus the ultrasonic wave at a desired point by controlling the output timing of the ultrasonic wave from the plurality of piezoelectric elements 10. In the present embodiment, an ultrasonic transmission array in which a plurality of piezoelectric elements 10 for ultrasonic transmission are arranged on the substrate 11 is illustrated. For example, the piezoelectric elements 10 may function as ultrasonic receiving elements. it can. In this case, for example, half of the piezoelectric elements 10 arranged in a lattice shape may function as an ultrasonic transmission element, and the other half may function as an ultrasonic reception element. Alternatively, the piezoelectric element 10 may function as an ultrasonic transmission element to transmit ultrasonic waves, and then function as an ultrasonic reception element to receive reflected ultrasonic waves. Furthermore, although an ultrasonic sensor has been exemplified as the piezoelectric sensor, for example, it may be used as a pressure detection sensor for measuring a contact pressure when a contact object comes in contact with the piezoelectric sensor. It is good also as a sensor etc. which give a driving force to a thing.

In such an ultrasonic sensor 1, since the ultrasonic wave is focused at a desired position by changing the transmission timing of the ultrasonic wave output from each piezoelectric element 10, an independent lower electrode is provided for each piezoelectric element 10. A line portion 22 is provided.
Specifically, as shown in FIG. 10, the lower electrode line portion 22 of each piezoelectric element 10 is continuous with the lower electrode main body portion 21, and is connected to an element connection line 221 formed across the inside and outside of the membrane 121. And a lower electrode wiring 222 that connects the connection line 221 to the lower electrode terminal portion 23. Here, since a plurality of lower electrode wirings 222 are formed between the membranes 121 of each piezoelectric element 10, the line width dimension of these lower electrode wirings 222 is smaller than the element connection line 221 in the layout. Is formed. For this reason, the lower electrode wiring 222 has a larger electrical resistance than the element connection line 221.
In such an ultrasonic sensor 1, if the lower electrode wiring 222 is over-etched when the piezoelectric body of each piezoelectric element 10 and the upper electrode layer 50 are formed, the electrical resistance is further increased, and the piezoelectric element 10 generates a desired value. It is necessary to apply a high voltage in order to output sound pressure ultrasonic waves. In this case, it becomes difficult to control the driving of the piezoelectric element 10 particularly in a high frequency range. On the other hand, in the present embodiment, the second piezoelectric layer 40 is formed on the lower electrode wiring 222 whose line width dimension is smaller than that of the element connection line 221. For this reason, when the sensor is manufactured, the lower electrode wiring 222 is not over-etched, and an increase in electrical resistance can be suppressed.

In the ultrasonic sensor 1 of the fourth embodiment, the upper electrode line portion 52 is common to the piezoelectric elements 10 arranged in one direction (the horizontal direction in FIG. 10), for example, as shown in FIG. Is formed.
Here, these upper electrode line portions 52 are formed on the second piezoelectric layer 40 as in the third embodiment. Therefore, it is possible to form a wiring pattern in which the upper electrode line portion 52 and the lower electrode wiring 222 are brought close to each other in plan view without bringing the upper electrode line portion 52 and the lower electrode wiring 222 into contact with each other. By setting it as such a structure, the arrangement | positioning space | interval of each piezoelectric element 10 can be shortened, and the size of the board | substrate 11 of the ultrasonic sensor 1 can be reduced in size.
In the example shown in FIG. 10, each lower electrode wiring 222 and the upper electrode line portion 52 are arranged so as not to overlap each other in plan view. For example, in plan view, the upper electrode line portion 52 and the lower electrode wiring portion are arranged. 222 may be provided at a position overlapping with 222.

  In the present embodiment, the example in which the upper electrode line portion 52 is used as a common line between the plurality of piezoelectric elements 10 has been described. However, for example, the lower electrode wiring 222 may be shared. In this case, the line width dimension of the lower electrode wiring 222 can be formed large, and since the second piezoelectric layer 40 can be provided to prevent over-etching during manufacturing, the electrical resistance can be increased more reliably. Can be suppressed.

[Effects of the fourth embodiment]
The ultrasonic sensor 1 of the fourth embodiment has an array structure in which a plurality of piezoelectric elements 10 are arranged. In such an ultrasonic sensor 1, when the lower electrode line portion 22 is formed on the substrate 11, it is necessary to arrange a plurality of lower electrode wirings 222 between the piezoelectric elements 10, the line width dimension thereof is restricted, and the electric resistance Will increase. In such an ultrasonic sensor 1, when the lower electrode wiring 222 is over-etched at the time of manufacture, the electrical resistance is further increased, the sound pressure of the output ultrasonic wave is reduced, and the drive control in the high frequency range is difficult. It becomes. On the other hand, in the present embodiment, the second piezoelectric layer 40 is formed on the lower electrode wiring 222, whereby over-etching of the lower electrode wiring 222 during manufacturing can be prevented, and an increase in electrical resistance can be suppressed. .

  Further, by forming the upper electrode line portion 52 on the second piezoelectric layer 40, it is possible to prevent the lower electrode wiring 222 and the upper electrode line portion 52 from contacting each other. Further, in plan view, the lower electrode wiring 222 and the upper electrode line portion 52 can be formed at the overlapping position, the distance between the piezoelectric elements 10 can be shortened, and the ultrasonic sensor 1 can be reduced in size.

[Fifth embodiment]
Next, as a fifth embodiment, an electronic apparatus of the present invention including the piezoelectric element 10 as described above will be described. In the fifth embodiment, a PDA (Personal Data Assistance) is exemplified as an electronic device.
FIG. 11 is a perspective view schematically showing the configuration of the PDA of the fifth embodiment. FIG. 12 is a perspective view schematically showing a configuration of an ultrasonic sensor provided in the PDA.

  In FIG. 11, the PDA 100 includes an apparatus main body 2 and a display unit 3. The display unit 3 is composed of, for example, a liquid crystal panel or an organic panel, and is connected to an arithmetic control unit 13 (see FIG. 12) housed in the apparatus main body 2. The arithmetic control unit 13 allows various operation images and It is configured to display other information. An ultrasonic sensor 1 </ b> A that is a piezoelectric sensor of the present invention is disposed on the outer periphery of the apparatus main body 2. As shown in FIG. 12, the ultrasonic sensor 1A includes a plurality of ultrasonic elements 10A for transmitting ultrasonic waves and a plurality of piezoelectric elements 10B for receiving ultrasonic waves. These piezoelectric elements 10A and 10B are arranged in an array structure as shown in FIG. 10 as in the ultrasonic sensor 1 of the fourth embodiment, and are arranged in an outer region of the membrane 121 in the lower electrode line portion 22. The second piezoelectric layer 40 is laminated on the lower electrode wiring 222 to be formed.

In the PDA of the fifth embodiment as described above, the second piezoelectric layer 40 is formed on the lower electrode wiring 222 formed in the outer region of the membrane 121 in the lower electrode line portion 22. Therefore, in such an ultrasonic sensor 1A, there is no over-etching of the lower electrode wiring 222 at the time of manufacture, and there is no increase in electrical resistance due to this. For this reason, the piezoelectric element 10A for transmitting ultrasonic waves can transmit ultrasonic waves having a large sound pressure with a smaller driving voltage. In addition, the piezoelectric element 10B for receiving ultrasonic waves can suppress the attenuation of an electric signal output by ultrasonic reception. That is, it is possible to perform transmission / reception of ultrasonic waves with high accuracy of the ultrasonic sensor 1A and to save power.
Therefore, in a PDA equipped with such an ultrasonic sensor 1A, the position of a finger or touch pen located on the display unit 3 can be detected with high accuracy, and power consumption can also be suppressed.

  In the fifth embodiment, the input device of the PDA 100 in which the ultrasonic sensor 1A is incorporated is shown as an example to which the piezoelectric element and the piezoelectric sensor of the present invention are applied. However, the present invention is not limited to this. For example, the piezoelectric element or the piezoelectric sensor of the present invention can be applied as an input device in a portable game machine, a mobile phone, a personal computer, an electronic dictionary, or the like. In addition to an input device, for example, a cleaning device that cleans an object with ultrasonic waves, a proximity sensor or a distance measurement sensor that is incorporated in, for example, a robot or an automobile, and measures the distance or speed to the target object, piping Applicable to any device that performs various processes by ultrasonic output, such as non-destructive inspection, measurement sensor that monitors the flow velocity of fluid in piping, and biological inspection device that inspects the state of the living body by ultrasound. Can do. Further, the present invention is not limited to transmission / reception of ultrasonic waves, and can also be used as, for example, a braille display device that displays braille by vibration of the membrane 121, or a drive device that drives an object in contact with the membrane 121 by vibration of the membrane 121. .

[Other Embodiments]
It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

  For example, the second piezoelectric layer 40 is connected to the lower electrode terminal portion 23 and the lower electrode line portion 22 from an end portion 22A of the lower electrode layer 20 that is separated from the edge 111A of the opening 111 by a distance L. Although the example formed to cover up to the portion 22B has been shown, for example, a configuration covering the edge 111A of the opening 111 to the connecting portion 22B may be employed. Even in this case, for example, the resistance to the bending of the membrane 121 can be reduced as compared with a configuration in which the second piezoelectric layer 40 is formed inside and outside the opening 111.

Further, the second piezoelectric layer 40 may be formed on a part of the edge 111 </ b> A of the opening 111. For example, the second piezoelectric layer 40 may be formed only at a position where the lower electrode line portion 22 is formed, straddling the edge 111A of the opening 111, and inside and outside the opening 111. The portion exposed to the outside of the line portion 22 is eliminated, and overetching can be reliably prevented when the piezoelectric layer 60 and the upper electrode layer 50 are etched, and an increase in electrical resistance can be suppressed more reliably. Further, compared to the configuration in which the second piezoelectric layer 40 is formed over the entire circumference of the edge 111A of the opening 111, the resistance to the bending of the membrane 121 does not increase, and an ultrasonic wave with a high sound pressure is generated. It can also be output.
Furthermore, the second piezoelectric layer 40 is not formed only within a distance L from the edge 111A of the opening 111 that may inhibit the vibration of the membrane 121, and the second piezoelectric layer 40 is formed in all other regions. 40 may be formed.

  Moreover, although the said embodiment illustrated the structure in which the lower electrode layer 20 is formed on the support film 12, it is not limited to this. For example, the support film 12 may be etched, and another layer such as an insulating layer may be stacked at the etching site, and the lower electrode layer 20 may be formed on the other layer.

  Although the best configuration for carrying out the present invention has been specifically described above, the present invention is not limited to this. That is, the present invention has been illustrated and described primarily with respect to particular embodiments, but the present invention is not limited to the embodiments described above without departing from the scope of the technical idea and object of the present invention. Various modifications and improvements can be made by a trader.

  DESCRIPTION OF SYMBOLS 1,1A ... Ultrasonic sensor as a piezoelectric sensor, 10, 10A, 10B ... Piezoelectric element, 11 ... Substrate which is a support body, 12 ... Support film, 20 ... Lower electrode layer, 21 ... Lower electrode main body part, 22 ... Lower part Electrode wire portion, 30 ... first piezoelectric layer, 40, 40A ... second piezoelectric layer, 50 ... upper electrode layer, 111 ... opening, 111A ... edge that is the outer periphery of the displacement portion, 121 ... displacement portion A certain membrane, 60 ... piezoelectric layer, 70, 70A ... auxiliary electrode layer which is a wiring layer, 221 ... element connection line, 222 ... lower electrode wiring.

Claims (6)

A support having a displacement portion that is displaceable along the thickness direction;
On the support, in a plan view of the support viewed from the thickness direction of the displacement portion , a first electrode body portion provided in an inner region of an outer peripheral edge of the displacement portion, and connected to the first electrode body portion It is, and a first electrode layer having a first electrode line portion provided from the inner region of the outer peripheral edge of the front Symbol displacement portion over the outer region,
In the plan view, a first piezoelectric layer provided on the first electrode main body in an inner region than an outer peripheral edge of the displacement portion;
In the plan view, Ri least partially Do weight and the first piezoelectric layer, the second electrode body portion provided in the inner area of the outer peripheral edge of the displacement portion, and is connected to the second electrode body portion, and a second electrode layer to have a second electrode line portion provided from the inner region of the outer peripheral edge of the front Symbol displacement portion over the outer region,
On the support, in a plan view, the first electrode line portion is provided at a position that does not overlap the outer peripheral edge of the displacement portion and covers at least a part of the first electrode line portion. Two piezoelectric layers,
The piezoelectric element, wherein at least a part of the second electrode line portion is provided along a direction intersecting the first electrode line portion on the second piezoelectric layer in the plan view. The piezoelectric element according to claim 1 .
A piezoelectric element, wherein a wiring layer is provided on the second piezoelectric layer. The piezoelectric element according to claim 2 ,
The piezoelectric element is characterized in that the wiring layer is electrically connected between two different points of the first electrode line portion. The piezoelectric element according to any one of claims 1 to 3 ,
The first electrode wire portion is
In the plan view, across the outer region from the inner region of the outer peripheral edge of the displacement portion, the element connection line connected to the first electrode main body,
A first electrode wiring that is continuous with the element connection line, is provided in an outer region of an outer peripheral edge of the displacement portion, and has a line width smaller than the line width of the element connection line in the plan view;
The second piezoelectric layer is provided so as to cover the first electrode wiring. A support body having a displacement portion that is displaceable along the thickness direction, and provided on an inner region of the outer peripheral edge of the displacement portion on the support body in a plan view when the support body is viewed from the thickness direction of the displacement portion. the first electrode body portions, and connected to the first electrode main body, and, prior Symbol first electrode layer having a first electrode line portion from the inner region of the outer peripheral edge is provided across the outer region of the displacement unit When, in the plan view, the inside area of the outer peripheral edge of the displacement portion, a first piezoelectric layer provided on the first electrode main part on, in the plan view, at least a part of said first piezoelectric body layer and heavy Do Ri, second electrode body portion provided in the inner area of the outer peripheral edge of the displacement portion, and is connected to the second electrode body portion and the inner region of the outer peripheral edge of the front Symbol displacement unit a second electrode layer to have a second electrode line portion provided across the outer region On the support, in the plan view, the in a position that does not cover the outer peripheral edge of the displacement portion is provided along the first electrode line portion, and covers at least a portion of the first electrode line portion The second electrode line portion is provided at least partially along a direction intersecting the first electrode line portion on the second piezoelectric layer in the plan view. A piezoelectric sensor comprising a plurality of piezoelectric elements, wherein the plurality of piezoelectric elements are arranged in an array. A support body having a displacement portion that is displaceable along the thickness direction, and provided on an inner region of the outer peripheral edge of the displacement portion on the support body in a plan view when the support body is viewed from the thickness direction of the displacement portion. the first electrode body portions, and connected to the first electrode main body, and, prior Symbol first electrode layer having a first electrode line portion from the inner region of the outer peripheral edge is provided across the outer region of the displacement unit When, in the plan view, the inside area of the outer peripheral edge of the displacement portion, a first piezoelectric layer provided on the first electrode main part on, in the plan view, at least a part of said first piezoelectric body layer and heavy Do Ri, second electrodes body portion provided in the inner area of the outer peripheral edge of the displacement portion, and is connected to the second electrode body portion and the inner region of the outer peripheral edge of the front Symbol displacement unit a second electrode layer to have a second electrode line portion provided across the outer region On the support, in the plan view, the in a position that does not cover the outer peripheral edge of the displacement portion is provided along the first electrode line portion, and covers at least a portion of the first electrode line portion The second electrode line portion is provided at least partially along a direction intersecting the first electrode line portion on the second piezoelectric layer in the plan view. An electronic device comprising a piezoelectric element.

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