TWI689856B - Piezoelectric sensor - Google Patents

Abstract

A piezoelectric sensor includes a substrate, a plurality of active devices, a plurality of electrodes, and a piezoelectric film. The active devices are disposed on the substrate. The electrodes are disposed on the substrate and electrically connected to the active devices. The piezoelectric film is disposed on the electrodes and has a first surface facing the first electrode and a second surface disposed opposite to the first surface. The first surface of the piezoelectric film has a plurality of first recesses and a plurality of first protrusions defined by the first recesses. The second surface of the piezoelectric film has a plurality of second recesses and a plurality of second protrusions defined by the second recesses. The first protrusions are disposed corresponding to the second protrusions, and the first recesses are disposed corresponding to the second recesses.

Description

Piezoelectric Inductor

The invention relates to a sensor, and in particular to a piezoelectric sensor.

At present, flexible piezoelectric materials (for example, commercially available polyvinylidene fluoride (PVDF) films) can be attached to arrayed thin film transistor substrates to form arrayed piezoelectric sensors and applied in Sonic sensing or speakers. Among them, the arrayed thin film transistor can be used to collect a specific small range of piezoelectric information in a large area, and can be made into a high-definition/resolution piezoelectric sensing element.

As the resolution requirements of piezo-electric sensors increase, the area of each electrode on the arrayed thin film transistor substrate is bound to shrink, thus reducing the single-point signal available for small-area electrodes. Therefore, it is necessary to increase the thickness of the piezoelectric material to generate a larger signal in order to increase the single-point signal that can be obtained with a small-area electrode. However, the thicker piezoelectric material and the smaller and denser electrodes will cause more serious crosstalk, thereby reducing the resolution of the piezoelectric sensor.

The invention provides a piezoresistive sensor, which can improve the problem of mutual interference and has better resolution.

The piezoelectric sensor of the present invention includes a substrate, a plurality of active elements, a plurality of electrodes, and a piezoelectric film. The active element is arranged on the substrate. The electrode is disposed on the substrate and is electrically connected to the active device. The piezoelectric film is disposed on the electrode, and has a first surface facing the electrode and a second surface facing the first surface. The first surface of the piezoelectric film has a plurality of first concave portions and a plurality of first convex portions defined by the first concave portions. The second surface of the piezoelectric film has a plurality of second concave portions and a plurality of second convex portions defined by the second concave portions. The first convex portion corresponds to the second convex portion, and the first concave portion corresponds to the second concave portion.

In an embodiment of the invention, there is a solid material portion of the piezoelectric film between one of the above-mentioned first recesses and a corresponding one of the second recesses.

In an embodiment of the present invention, the above-mentioned first convex portions respectively overlap the second convex portions, and the first concave portions overlap the second concave portions, respectively.

In an embodiment of the invention, the above-mentioned first convex portions are respectively provided on the electrodes.

In an embodiment of the invention, the above-mentioned electrodes are separated from each other and arranged in an array on the substrate.

In an embodiment of the invention, the material of the piezoelectric film includes polyvinylidene fluoride, polyvinylidene fluoride and its copolymer, polyvinyl fluoride, polyvinyl chloride or poly-γ-methyl-L-valley Aminoester or nylon-11.

In an embodiment of the present invention, the above-mentioned electrodes include transparent electrodes, reflective electrodes, or a combination thereof.

In order to make the above-mentioned features and advantages of the present invention more obvious and understandable, the embodiments are specifically described below in conjunction with the accompanying drawings for detailed description as follows.

Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same element symbols are used in the drawings and description to denote the same or similar parts.

FIG. 1A is a schematic top view of a piezoelectric sensor according to an embodiment of the invention. FIG. 1B is a schematic cross-sectional view of a piezoelectric sensor according to an embodiment of the present invention corresponding to section line A-A' of FIG. 1A.

Referring to FIGS. 1A and 1B, the piezoelectric sensor 100 of this embodiment includes an active device substrate 110 and a piezoelectric film 120 disposed on the active device substrate 110. The active device substrate 110 includes a base 111, a plurality of active devices 112, a plurality of electrodes 113, a dielectric layer 114 and a plurality of contact windows 115. Among them, the active element 112 is disposed on the substrate 111. The dielectric layer 114 is disposed on the substrate 111 and covers the active device 112. The contact window 115 penetrates through the dielectric layer 114. The electrode 113 is disposed on the dielectric layer 114 and is electrically connected to the active device 112 through the contact window 115. The substrate 111 may be a hard board or a soft board. For example, the hard board may be, for example, glass or silicon wafer, and the soft board may be, for example, polyimide or other plastic flexible boards, but the invention is not limited thereto.

In detail, in this embodiment, the active device 112 includes a thin film transistor, which has a gate electrode 1121, a gate insulating layer 1122, a channel layer 1123, a source electrode 1124, and a drain electrode 1125. The channel layer 1122 is disposed on the gate electrode 1121, the channel layer 1122 overlaps with the gate electrode 1121, and a gate insulating layer 1122 is sandwiched between the channel layer 1123 and the gate electrode 1121. The source 1124 and the drain 1125 are disposed on the gate insulating layer 1122, and the source 1124 and the drain are electrically connected to the channel layer 1120, respectively.

In this embodiment, the channel layer 1122 is disposed on the gate 1121, that is to say, the active device 112 can be selectively a bottom gate type thin film transistor. However, the present invention is not limited to this. In other embodiments, the active device 112 may also include any other form of thin film transistors, such as: top gate thin film transistors, etch stop (Island stop; IS) thin film transistors Crystals, etc. In addition, in this embodiment, the material of the channel layer 1122 of the thin film transistor can be optionally amorphous silicon. However, the present invention is not limited to this. In other embodiments, the material of the channel layer 1122 may also be any other type of semiconductor, such as: low temperature poly-silicon (LTPS), polycrystalline silicon, microcrystalline silicon, single crystal Silicon, organic semiconductor materials, oxide semiconductor materials, or other suitable materials, or containing dopants in the above materials, or a combination thereof.

In this embodiment, the electrode 113 and the active device 112 can be selectively located on opposite sides of the dielectric layer 114. The electrode 113 can be electrically connected to the active device 112 through the contact window 115. In addition, in the present embodiment, the plurality of electrodes 113 may be separated from each other and arranged in an array on the substrate 111. That is to say, a plurality of electrodes 113 can form a patterned electrode layer, but the invention is not limited thereto. Although FIG. 1A shows 30 electrodes 113, and a plurality of electrodes 113 are arranged on the substrate 111 in a 5×6 array, the present invention does not limit the number and arrangement of the electrodes 113. In some embodiments, the electrode 113 may include a transparent electrode, a reflective electrode, or a combination thereof.

In this embodiment, the piezoelectric film 120 is disposed on the plurality of electrodes 113, and the piezoelectric film 120 and the dielectric layer 114 are respectively located on opposite sides of the plurality of electrodes 113. For example, the material of the piezoelectric film 120 includes polyvinylidene fluoride (PVDF), polyvinylidene fluoride, and copolymers thereof (eg, vinylidene fluoride-trifluoroethylene copolymer or vinylidene fluoride) -Copolymer of tetrafluoroethylene, etc.), polyvinyl fluoride, polyvinyl chloride or poly-γ-methyl-L-glutamate or nylon-11. It should be noted that the piezoelectric film 120 must be closely connected with the electrode 113 to have a better piezoelectric induction effect. In addition, in this embodiment, the connection method of the piezoelectric film 120 and the electrode 113 may be, for example, directly connecting or attaching the piezoelectric film 120 to the electrode 113, or vacuum-sealing the piezoelectric film 120 and the electrode 113 is closely connected, but the invention is not limited to this. In other embodiments, the piezoelectric film 120 may be tightly connected to the electrode 113 by using a conductive adhesive material.

In detail, the piezoelectric film 120 has a first surface 121 facing the electrode 113 and an opposite second surface 122 disposed on the first surface 121. The first surface 121 of the piezoelectric film 120 has a plurality of first concave portions 123 and a plurality of first convex portions 124 defined by the first concave portions 123. The second surface 122 of the piezoelectric film 120 has a plurality of second concave portions 125 and a plurality of second convex portions 126 defined by the second concave portions 125. The first convex portion 124 corresponds to the second convex portion 126 and the first concave portion 123 corresponds to the second concave portion 125. In some embodiments, the first convex portions 124 may overlap the second convex portions 126, and the first concave portions 123 may overlap the second concave portions 125, respectively. In some embodiments, the vertical projection of the first recess 123 is located outside the vertical projection of the plurality of electrodes 113 and between the vertical projections of the plurality of electrodes 113, and the vertical projection of the second recess 125 is located outside the vertical projection of the plurality of electrodes 113 It is located between the vertical projections of the multiple electrodes 113, but the invention is not limited thereto.

In addition, in this embodiment, the plurality of first protrusions 124 are respectively provided on the plurality of electrodes 113, and the plurality of second protrusions 126 are respectively provided on the plurality of electrodes 113. That is to say, each first convex portion 124 may correspond to one electrode 113, and each second convex portion 126 may also correspond to one electrode 113, but the invention is not limited thereto. In other embodiments, each first convex portion 124 may also correspond to multiple electrodes 113, and each second convex portion 126 may also correspond to multiple electrodes 113.

In particular, in this embodiment, there is a solid material portion 127 of the piezoelectric film 120 between one first concave portion 123 and a corresponding second concave portion 125. That is, although the piezoelectric film 120 has the first concave portion 123 and the second concave portion 125, the piezoelectric film 120 is not disconnected by the first concave portion 123 and/or the second concave portion 125, as shown in FIG. 1B.

In this embodiment, the method of forming the first concave portion 123, the second concave portion 125, the first convex portion 124, and the second convex portion 126 of the piezoelectric film 120 includes knife film stamping, laser cutting, or the like. In detail, the knife film tool is a knife film tool designed according to the arrangement of the electrodes 113, so that the knife film tool can cut a score (ie, the first concave portion 123) on the first surface 121 of the piezoelectric film 120 ), and a notch (ie, the second concave portion 125) can be cut on the second surface 122 of the piezoelectric film 120, but the piezoelectric film 120 is not cut. The size of the first convex portion 124 defined by the first concave portion 123 may correspond to the size of the electrode 113, and the size of the second convex portion 126 defined by the second concave portion 125 may also correspond to the size of the electrode 113.

In addition, laser cutting can also be used to cut a score (ie, the first concave portion 123) on the first surface 121 of the piezoelectric film 120, and cut a score (ie, the first concave portion 123) on the second surface 122 of the piezoelectric film 120. The second recess 125), but does not cut the piezoelectric film 120. The size of the first convex portion 124 defined by the first concave portion 123 may correspond to the size of the electrode 113, and the size of the second convex portion 126 defined by the second concave portion 125 may also correspond to the size of the electrode 113. However, it should be noted that, when cutting with a laser, an appropriate laser wavelength and power should be selected to avoid that the heat-affected zone generated by the laser cutting of the piezoelectric film 120 is too large to cause the first convex portion 124 or The piezoelectric characteristic at the second convex portion 126 fails. For example, when PVDF is used as the material of the piezoelectric film, the processing temperature of the PVDF and the process of connecting the PVDF to the active device substrate 110 need to be less than 70°C to avoid the failure of the piezoelectric characteristics of the PVDF.

FIG. 2A is a schematic cross-sectional view of a piezoelectric sensor according to an embodiment of the present invention when an external force is applied. 2B is a schematic cross-sectional view of a piezoelectric sensor according to a comparative example of the present invention when an external force is applied. 2C is a schematic cross-sectional view of a piezoelectric sensor according to another comparative example of the present invention.

2A, in the piezoelectric sensor 100a of this embodiment, the first surface 121a of the piezoelectric film 120a has a plurality of first convex portions 124a, 124b, 124c, and the second surface 122a has a plurality of second The convex portions 126a, 126b, 126c. The second convex portion 126a corresponds to the first convex portion 124a and the electrode 113a1, the second convex portion 126b corresponds to the first convex portion 124b and the electrode 113a2, and the second convex portion 126c corresponds to the first convex portion 124c and the electrode 113a3 . When an external force F is applied to the position P1 on the piezoelectric film 120a, only the second convex portion 126b corresponding to the position P1 is deformed, and the deformed second convex portion 126b generates an electric charge to make the electrode below it 113a2 and the piezoelectric signal is received. Since the piezoelectric film 120 has a plurality of first concave portions 123 and a plurality of second concave portions 125, the deformation of the second convex portion 126b itself is not likely to cause deformation of other surrounding second convex portions 126a, 126c, which may further Avoid crosstalk situations.

However, referring to FIG. 2B, in the piezoelectric sensor 200 as a comparative example, the piezoelectric film 220 has a flat first surface 221 and a second surface 222. That is, the piezoelectric film 220 does not have a plurality of first convex portions 124a, 124b, 124c and a plurality of second convex portions 126a, 126b, 126c as in FIG. 2A. Therefore, when an external force F is applied to the position P2 on the piezoelectric film 220, the piezoelectric film 220 corresponding to the position P2 and its surroundings will be deformed, and the deformed piezoelectric film 220 will generate electric charges and make it below The plurality of electrodes 213a1, 213a2, 213a3 receive piezoelectric signals. Therefore, in addition to the piezoelectric signal received by the electrode 213a2 corresponding to the position P2, the external force F also deforms the piezoelectric film 220 corresponding to the position P2, and also causes the other electrodes 213a1 and 213a3 around the electrode 213a2 The piezoelectric signal is received, which causes mutual interference.

Next, referring to FIG. 2C, in the piezoelectric sensor 300 as a comparative example, the first surface 321 of the piezoelectric film 320 has a plurality of first convex portions 324, but the second surface 322 is a flat surface. In other words, when only one side (first surface 321) of the piezoelectric film 320 has cutting marks and the other side (second surface 322) is flat, the stress imbalance between the first surface 321 and the second surface 322 may cause The piezoelectric film 320 is warped, which is not conducive to the sensing effect of the piezoelectric sensor 300.

In short, the piezoelectric sensor 100 of this embodiment includes a substrate 111, a plurality of active elements 112, a plurality of electrodes 113, and a piezoelectric film 120. The active element 112 is disposed on the substrate 111. The electrode 113 is disposed on the substrate 111 and electrically connected to the active device 112. The piezoelectric film 120 is disposed on the electrode 113 and has a first surface 121 facing the electrode 113 and an opposite second surface 122 disposed on the first surface 121. The first surface 121 of the piezoelectric film 120 has a plurality of first concave portions 123 and a plurality of first convex portions 124 defined by the first concave portions 123. The second surface 122 of the piezoelectric film 120 has a plurality of second concave portions 125 and a plurality of second convex portions 126 defined by the second concave portions 125. The first convex portion 124 is provided corresponding to the second convex portion 126, and the first concave portion 123 is provided corresponding to the second concave portion 125. With this design, the piezoelectric sensor 100 of this embodiment can improve the problem of mutual interference and have better resolution.

The piezoresistive sensor 100 is used to detect the force distribution state on the piezoresistive sensor 100. For example, in this embodiment, the piezoresistive sensor 100 can be placed on the wrist to detect the beating of the radial artery of the wrist to obtain the pulse waveform of the radial artery. However, the present invention is not limited to this, and the piezoelectric sensor 100 can also be used in other applications.

The following will list other embodiments as illustrations. It must be noted here that the following embodiments follow the element numbers and partial contents of the foregoing embodiments, wherein the same reference numbers are used to indicate the same or similar elements, and the description of the same technical content is omitted. For the description of the omitted parts, reference may be made to the foregoing embodiments, and the following embodiments will not be repeated.

3 is a schematic cross-sectional view of a piezoelectric sensor according to another embodiment of the invention. Please refer to FIGS. 1B and 3 at the same time. The piezoelectric inductor 100b of this embodiment is similar to the piezoelectric inductor 100 of FIG. 1B, but the main difference between the two is that: the piezoelectric inductor of this embodiment 100b further includes a connection element 130 disposed between the piezoelectric film 120 and the electrode 113. The connection element 130 has electrical conductivity and viscosity, so that the piezoelectric film 120 can be tightly connected to the electrode 113 and electrically connected to the electrode 113 through the connection element 130. Therefore, in this embodiment, the connecting element 130 may be conductive adhesive or other conductive adhesive material.

4 is a schematic cross-sectional view of a piezoelectric sensor according to another embodiment of the invention. Please refer to FIG. 1B and FIG. 4 at the same time, the piezoelectric inductor 100c of this embodiment is similar to the piezoelectric inductor 100 of FIG. 1B, but the main difference between the two is that: In the device 100c, the vertical projection of the first concave portion 123 of the piezoelectric film 120 overlaps the vertical projection of one of the electrodes 113. That is to say, the first convex portion 124 and the second convex portion 126 of the piezoelectric film 120 and the plurality of electrodes 113 may not require extremely precise alignment, and the piezoelectric sensor 100c may still have the effect of improving mutual interference .

In summary, in the piezoelectric sensor of the present invention, the piezoelectric film is disposed on the electrode, and has a first surface facing the electrode and a second surface opposite to the first surface. Wherein, the first surface of the piezoelectric film has a plurality of first concave portions and a plurality of first convex portions defined by the first concave portions. The second surface of the piezoelectric film has a plurality of second concave portions and a plurality of second convex portions defined by the second concave portions. The first convex portion corresponds to the second convex portion, and the first concave portion corresponds to the second concave portion. With this design, the piezoelectric sensor of the present invention can improve the problem of mutual interference and have better resolution.

Although the present invention has been disclosed as above with examples, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present invention. The scope of protection of the present invention shall be subject to the scope defined in the appended patent application.

100, 100a, 100b, 100c, 200, 300: piezoresistive sensor

110: Active component substrate

111: base

112: Active components

1121: Gate

1122: Gate insulation

1123: Channel layer

1124: source

1125: Drain

113, 113a1, 113a2, 113a3, 213a1, 213a2, 213a3:: electrode

114: Dielectric layer

115: contact window

120, 120a, 220, 320: piezoelectric film

121, 121a, 221, 321: the first surface

122, 122a, 222, 322: second surface

123: First recess

124, 124a, 124b, 124c, 324: first convex part

125: second recess

126, 126a, 126b, 126c: second convex part

127: Physical Materials Department

130: connecting element

F: external force

P1, P2: location

FIG. 1A is a schematic top view of a piezoelectric sensor according to an embodiment of the invention. FIG. 1B is a schematic cross-sectional view of a piezoelectric sensor according to an embodiment of the present invention corresponding to section line A-A' of FIG. 1A. FIG. 2A is a schematic cross-sectional view of a piezoelectric sensor according to an embodiment of the present invention when an external force is applied. 2B is a schematic cross-sectional view of a piezoelectric sensor according to a comparative example of the present invention when an external force is applied. 2C is a schematic cross-sectional view of a piezoelectric sensor according to another comparative example of the present invention. 3 is a schematic cross-sectional view of a piezoelectric sensor according to another embodiment of the invention. 4 is a schematic cross-sectional view of a piezoelectric sensor according to another embodiment of the invention.

100: Piezoelectric sensor

110: Active component substrate

111: base

112: Active components

1121: Gate

1122: Gate insulation

1123: Channel layer

1124: source

1125: Drain

113: electrode

114: Dielectric layer

115: contact window

120: Piezo film

121: The first surface

122: Second surface

123: First recess

124: first convex

125: second recess

126: Second convex part

127: Physical Materials Department

Claims (17)

A piezoresistive sensor includes: a substrate; a plurality of active elements disposed on the substrate; a plurality of electrodes disposed on the substrate and electrically connected to the active elements; and a piezoelectric film disposed on The electrodes have a first surface facing the electrodes and a second surface opposite to the first surface; wherein the first surface of the piezoelectric film has a plurality of first recesses and the A plurality of first convex portions defined by the first concave portions, the second surface of the piezoelectric film has a plurality of second concave portions and a plurality of second convex portions defined by the second concave portions, the first convex portions The portion corresponds to the second convex portions, and the first concave portions correspond to the second concave portions, and the vertical projection of one of the first concave portions and/or one of the second concave portions is located The vertical projection of one of the electrodes is outside and between the vertical projections of the adjacent electrodes. The piezoresistive sensor according to item 1 of the patent application scope, wherein one of the first concave portions and one of the corresponding second concave portions has a solid material portion of the piezoelectric film. The piezoresistive sensor according to item 1 of the patent application scope, wherein the first convex portions overlap the second convex portions, respectively, and the first concave portions overlap the second concave portions, respectively. The piezoresistive sensor according to item 1 of the patent application scope, wherein the first convex portions are respectively disposed on the electrodes. The piezoresistive sensor as described in item 1 of the patent application range, wherein the electrodes are separated from each other and arranged in an array on the substrate. The piezoresistive sensor as described in item 1 of the patent application range, wherein the material of the piezoelectric film includes polyvinylidene fluoride, polyvinylidene fluoride and its copolymer, polyvinyl fluoride, polyvinyl chloride or poly-γ -Methyl-L-glutamate or nylon-11. The piezoresistive sensor as described in item 1 of the patent application range, wherein the electrodes include a transparent electrode, a reflective electrode, or a combination thereof. The piezoresistive sensor according to item 1 of the patent application scope, wherein the vertical projections of one of the first recesses and one of the second recesses are outside the vertical projection of one of the electrodes, And it is located between the vertical projections of the adjacent electrodes. The piezoelectric sensor as described in item 1 of the patent application scope, wherein the piezoelectric sensor is placed on the wrist to detect the beating of the radial artery of the wrist and obtain the pulse waveform of the radial artery. The piezoresistive sensor as described in item 1 of the scope of the patent application further includes a connecting element disposed between the piezoelectric film and the electrodes. A piezoresistive sensor includes: a substrate; a plurality of active elements arranged on the substrate; a plurality of electrodes arranged on the substrate and electrically connected with the active elements respectively; And a piezoelectric film disposed on the electrodes, and having a first surface facing the electrodes and a second surface opposite to the first surface; wherein the first surface of the piezoelectric film There are a plurality of first concave portions and a plurality of first convex portions defined by the first concave portions, and the second surface of the piezoelectric film has a plurality of second concave portions and a plurality of second concave portions defined by the second concave portions Convex part, one of the first convex parts corresponds to and partially overlaps one of the second convex parts, and the vertical projection of one of the first concave parts overlaps the vertical of one of the electrodes projection. The piezoelectric sensor according to item 11 of the patent application scope, wherein a solid material portion of the piezoelectric film is provided between one of the first concave portions and one of the corresponding second concave portions. The piezoresistive sensor as recited in item 11 of the patent application range, wherein one of the first recesses corresponds to and partially overlaps with one of the second recesses, and one of the second recesses The vertical projection overlaps the vertical projection of one of the electrodes. Piezoelectric sensor as described in item 11 of the patent application range, wherein the material of the piezoelectric film includes polyvinylidene fluoride, polyvinylidene fluoride and its copolymer, polyvinyl fluoride, polyvinyl chloride or poly-γ -Methyl-L-glutamate or nylon-11. The piezoresistive sensor as described in item 11 of the patent application range, wherein the electrodes include a transparent electrode, a reflective electrode, or a combination thereof. The piezoelectric sensor according to item 11 of the patent application scope, wherein the piezoelectric sensor is placed on the wrist to detect the beating of the radial artery of the wrist and obtain the pulse waveform of the radial artery. The piezoresistive sensor as described in item 11 of the patent application scope further includes a connecting element disposed between the piezoelectric film and the electrodes.

Images