WO2018193824A1

WO2018193824A1 - Pyroelectric sensor element and pyroelectric sensor using same

Info

Publication number: WO2018193824A1
Application number: PCT/JP2018/014195
Authority: WO
Inventors: 寿彰堀江; 吉田　和司; 森川　顕洋; 高山　了一; 足立　秀明; 田中　良明; 是近　哲広
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2017-04-17
Filing date: 2018-04-03
Publication date: 2018-10-25
Also published as: WO2018193825A1

Abstract

This pyroelectric sensor element is equipped with a substrate, a membrane provided on the top surface of the substrate, a ferroelectric film provided on the top surface of the membrane, and an upper-section electrode provided on the top surface of the ferroelectric film. The substrate has a first section and a second section which is thinner than is the first section. The membrane includes a lower-section electrode, and the membrane is provided with a plurality of through-holes that pass through the membrane from the bottom surface thereof to the top surface thereof in a location overlapping the second section of the substrate when viewed from the top.

Description

Pyroelectric sensor element and pyroelectric sensor using the same

The present invention relates to a pyroelectric sensor used for gas detection and the like.

Patent Document 1 discloses a silicon substrate, a buffer layer made of zirconium oxide (ZrO ₂ ) provided on the silicon substrate, a lower electrode made of platinum (Pt) provided on the buffer layer, and provided on the lower electrode. A conventional structure having a piezoelectric film made of lead zirconate titanate (PZT) is disclosed. The piezoelectric film is formed by epitaxial growth. The lower electrode is used to control the crystal orientation of the piezoelectric film that is a ferroelectric. A sensor using the structure is known.

Patent Documents 2 and 3 disclose pyroelectric sensors that detect infrared light that has passed through a band-pass filter bonded to a can (cap) or the like with a pyroelectric sensor element. This bandpass filter transmits light of a specific wavelength.

Patent Documents

4 and 5 disclose a pyroelectric sensor including a light absorbing member provided on a light receiving portion constituted by a lower electrode, a pyroelectric body, and an upper electrode.

Patent Documents 6, 7, and 8 disclose pyroelectric sensors provided with a light receiving portion provided on a substrate provided with a cavity.

Patent Document 9 discloses a scanning pyroelectric sensor that scans a light receiving part using a movable part.

Patent Documents 10 and 11 disclose pyroelectric sensors each including a light receiving portion provided on a laminated structure of silicon oxide or silicon nitride.

JP 2010-238856 A JP-A-6-213711 JP2015-184627A Japanese Patent Laid-Open No. 2015-206595 Japanese Patent Laying-Open No. 2015-161642 Japanese Patent Laying-Open No. 2015-184151 US Patent No. 920712 US Pat. No. 8,648,303 JP 2014-6078 A JP 2000-112432 A Japanese Unexamined Patent Publication No. 7-94788

The pyroelectric sensor element includes a substrate, a membrane provided on the upper surface of the substrate, a ferroelectric film provided on the upper surface of the membrane, and an upper electrode provided on the upper surface of the ferroelectric film. The substrate has a first portion and a second portion that is thinner than the first portion. The membrane includes a lower electrode, and the membrane is provided with a plurality of through holes penetrating from the lower surface of the membrane to the upper surface of the membrane at a position overlapping the second portion of the substrate in a top view.

FIG. 1 is a cross-sectional view of a structure using a ferroelectric film in the embodiment. FIG. 2 is another cross-sectional view of the structure shown in FIG. FIG. 3 is a characteristic diagram showing the result of X-ray diffraction of the structure in the embodiment. FIG. 4 is another characteristic diagram showing the result of X-ray diffraction of the structure in the embodiment. FIG. 5 is still another characteristic diagram showing the result of X-ray diffraction of the structure in the embodiment. FIG. 6A is an exploded perspective view of the gyro sensor in the embodiment. 6B is a plan view of the sensor element of the gyro sensor shown in FIG. 6A. 6C is a cross-sectional view of the sensor element shown in FIG. 6B taken along line 6C-6C. FIG. 7A is a schematic cross-sectional view of the pyroelectric sensor in the embodiment. FIG. 7B is a perspective view of the pyroelectric sensor element of the pyroelectric sensor shown in FIG. 7A. FIG. 7C is a top view of the pyroelectric sensor element shown in FIG. 7B. FIG. 7D is a cross-sectional view of the pyroelectric sensor element shown in FIG. 7C taken along line 7D-7D. FIG. 8A is a top view of another pyroelectric sensor element in the embodiment. 8B is a cross-sectional view of the pyroelectric sensor element shown in FIG. 8A taken along line 8B-8B. FIG. 8C is a cross-sectional view illustrating a manufacturing process of the pyroelectric sensor element shown in FIG. 8A. FIG. 8D is a cross-sectional view illustrating a manufacturing process of the pyroelectric sensor element shown in FIG. 8A. FIG. 8E is a cross-sectional view illustrating a manufacturing process of the pyroelectric sensor element shown in FIG. 8A. FIG. 8F is a cross-sectional view illustrating a manufacturing process of the pyroelectric sensor element shown in FIG. 8A. FIG. 8G is a cross-sectional view illustrating a manufacturing process of the pyroelectric sensor element shown in FIG. 8A. FIG. 9A is a top view of still another pyroelectric sensor element in the embodiment. 9B is a cross-sectional view of the pyroelectric sensor element shown in FIG. 9A taken along line 9B-9B. FIG. 9C is a cross-sectional view of still another pyroelectric sensor element in the embodiment. FIG. 9D is a diagram for explaining the characteristics of the pyroelectric sensor element shown in FIG. 9A. FIG. 10A is a top view of still another pyroelectric sensor element according to the embodiment. FIG. 10B is a cross-sectional view of yet another pyroelectric sensor element taken along line 10B-10B in the embodiment. FIG. 10C is an enlarged cross-sectional view of the pyroelectric sensor element shown in FIG. 10B. FIG. 10D is a cross-sectional view of still another pyroelectric sensor element in the embodiment. FIG. 10E is a cross-sectional view of still another pyroelectric sensor element in the embodiment. FIG. 10F is a top view of still another pyroelectric sensor element in the embodiment. 10G is a cross-sectional view of the pyroelectric sensor element shown in FIG. 10F taken along line 10G-10G. FIG. 11A is a top view of still another pyroelectric sensor element according to the embodiment. 11B is a cross-sectional view of the pyroelectric sensor element shown in FIG. 11A taken along line 11B-11B. FIG. 11C is an enlarged view of the pyroelectric sensor element shown in FIG. 11A. FIG. 11D is an enlarged view of the pyroelectric sensor element shown in FIG. 11A. FIG. 11E is an enlarged view of the pyroelectric sensor element shown in FIG. 11A. FIG. 11F is an enlarged view of the pyroelectric sensor element shown in FIG. 11A. FIG. 11G is an enlarged view of the pyroelectric sensor element shown in FIG. 11A. FIG. 11H is an enlarged view of the pyroelectric sensor element shown in FIG. 11A. FIG. 12A is a top view of still another pyroelectric sensor element in the embodiment. 12B is a cross-sectional view of the pyroelectric sensor element taken along line 12B-12B shown in FIG. 12A. FIG. 12C is a diagram for explaining the characteristics of the pyroelectric sensor element shown in FIG. 12A. FIG. 13A is an enlarged view of the pyroelectric sensor element shown in FIG. 12A. FIG. 13B is an enlarged view of the pyroelectric sensor element shown in FIG. 12A. FIG. 13C is an enlarged view of the pyroelectric sensor element shown in FIG. 12A. FIG. 13D is an enlarged view of the pyroelectric sensor element shown in FIG. 12A. FIG. 13E is an enlarged view of the pyroelectric sensor element shown in FIG. 12A. FIG. 13F is an enlarged view of the pyroelectric sensor element shown in FIG. 12A. FIG. 13G is an enlarged view of the pyroelectric sensor element shown in FIG. 12A. FIG. 14A is a schematic cross-sectional view of the gas sensor in the embodiment. FIG. 14B is a schematic cross-sectional view of another gas sensor in the embodiment.

FIG. 1 is a cross-sectional view of a structure 10 using a ferroelectric film in the embodiment. The structure 10 includes a substrate 50, an intermediate film 40, a lower electrode 32, a ferroelectric film 20, and an upper electrode 31.

The ferroelectric film 20 is, for example, a perovskite complex oxide represented by the chemical formula ABO ₃ . Here, A and B represent cations. A is preferably one or more selected from Ca, Ba, Sr, Pb, K, Na, Li, La and Cd, and B is preferably one or more selected from Ti, Zr, Ta and Nb. Specifically, the ferroelectric film 20 is made of lead zirconate titanate (PZT), lead magnesium niobate-PZT (PMN-PZT), lead nickel niobate-PZT (PNN-PZT), magnesium. Lead niobate-lead titanate (PMN-PT), lead nickel niobate-PT (PNN-PT), sodium bismuth titanate-barium titanate (NBT-BT) or barium strontium titanate (BST) And the like are preferred. As the ferroelectric film 20, a laminated film in which a plurality of films made of the above materials are laminated may be used.

The substrate 50 is, for example, a (001) oriented MgO single crystal substrate, a (001) oriented yttria stabilized zirconia (YSZ) single crystal substrate, or a silicon single crystal having a (001) oriented YSZ epitaxial film on the surface. A substrate or the like is used.

The intermediate film 40 is provided on the substrate 50. The intermediate film 40 is made of an oxide having the chemical formula MIn ₂ O ₄ (M is a metal element). Here, for example, magnesium (Mg), zinc (Zn), or cadmium (Cd) is used as M. By providing the intermediate film 40, the orientation of the lower electrode 32 provided thereon is controlled.

The lower electrode 32 is made of a metal having a face-centered cubic structure, for example, platinum (Pt), gold (Au), iridium (Ir), palladium (Pd), and alloys or laminates thereof. By providing the lower electrode 32, the orientation of the ferroelectric film 20 provided thereon is controlled.

The ferroelectric film 20 is a film oriented in the c-axis direction. However, the crystal structure is not a complete (001) -oriented film, but a c-axis-oriented crystal that is a (001) -oriented crystal so that crystal grains are ideally filled with honey on the lower electrode 32; 100) A thin film in which a-axis oriented crystals, which are oriented crystals, are mixed appropriately.

The upper electrode 31 is a metal film made of, for example, platinum (Pt), gold (Au), copper (Cu), titanium (Ti), aluminum, or an alloy or a laminate thereof.

Preferably, MgIn ₂ O ₄ is used as the intermediate film 40. It has been confirmed by experiments that MgIn ₂ O ₄ can easily obtain an (002) -oriented epitaxial film in a wide range of 300 ° C. to 700 ° C. That is, there is no need to adjust the temperature before, during or after the formation of the MgIn ₂ O ₄ film. Also, the O ₂ partial pressure need not be adjusted during the formation of the MgIn ₂ O ₄ film. That is, it was confirmed by experiments that an MgIn ₂ O ₄ film can be formed without requiring special control and is excellent in mass productivity.

Platinum (Pt) is preferably used for the lower electrode 32. According to experiments, by forming a film made of Pt on a (002) -oriented epitaxial film of MgIn ₂ O ₄ , it is possible to obtain a (002) -oriented epitaxial film of Pt without special control. I understood.

The epitaxial film is a film that is uniaxially oriented in the direction perpendicular to the plane and biaxially in the plane. For this reason, whether the film is an epitaxial film can be verified by X-ray diffraction of the film. Specifically, first, it is confirmed by 2θ-θ scan whether or not uniaxial orientation is performed in the direction perpendicular to the plane. Next, the biaxial orientation in the plane is confirmed by confirming the symmetry of the crystal. Thereby, it can be confirmed whether the film is an epitaxial film. For example, in the case of a film oriented epitaxially in the [002] direction, it is first confirmed that it is oriented out of plane at (002) by 2θ-θ scanning. Next, the positional relationship of 2θ−θ of the X-ray diffractometer with respect to the crystal plane is fixed so as to detect the (202) plane, and the substrate is tilted by 45 ° from the perpendicular direction, and the in-plane 360 is fixed. X-ray diffraction is measured while rotating at a degree. At this time, if it can be confirmed that four peaks corresponding to four planes equivalent to the (202) plane appear at intervals of 90 degrees, it can be determined that the film is an epitaxial film. At this time, in the 2θ-θ scan, in addition to the peak corresponding to the main axis, a peak related to another axis is confirmed, or when checking in-plane symmetry, four periodic There may be some other peaks in addition to the peaks. However, if the intensity of other peaks is 1/10 or less of the main peak intensity, the film may be determined to be an epitaxial film. In the present embodiment, the (101) plane, the (202) plane, and the [001] direction and the [002] direction indicate parallel planes having different orders, and show equivalent directions and planes. It is assumed that

FIG. 2 is a cross-sectional view of the structure 10X used for the X-ray analysis of the film in the structure 10 shown in FIG. The structure 10X includes the substrate 50, the intermediate film 40, and the lower electrode 32 of the structure 10 shown in FIG. FIG. 3 is a characteristic diagram showing a result of 2θ-θ scan performed on the structure 10X shown in FIG. Here, a silicon single crystal substrate having a (001) -oriented YSZ epitaxial film on the surface is used as the substrate 50, an MgIn ₂ O ₄ film is used as the intermediate film 40, and a Pt film is used as the lower electrode 32.

In FIG. 4, the positional relationship of 2θ-θ of the X-ray diffractometer with respect to the crystal plane is fixed so as to detect the (202) plane of each of the MgIn ₂ O ₄ film and the Pt film, and the substrate 50 is further moved from the perpendicular direction to FIG. 6 is a characteristic diagram showing the result of X-ray diffraction measured while being rotated 360 degrees in the plane after being tilted.

The MgIn ₂ O ₄ film was prepared by RF magnetron sputtering. At this time, the substrate temperature was heated to 400 ° C., oxygen gas and argon gas were mixed and introduced at a ratio of 1: 1, the pressure was adjusted to 4 Pa, and sputtering was performed at a power of 80 W. The Pt film was formed by magnetron sputtering at 400 ° C.

In FIG. 3, simultaneously with the (002) peak and the higher order (004) peak of YSZ of the substrate 50, the (004) and higher order (008) of the MgIn ₂ O ₄ film formed thereon are formed. A peak can be confirmed. Thereby, it can be confirmed that the MgIn ₂ O ₄ film is oriented in the (002) direction out of the surface of the substrate 50. In addition, the (002) and higher (004) peaks can also be confirmed for the Pt film. Thereby, it can be confirmed that the Pt film is oriented in the (002) direction out of the plane of the substrate 50.

From FIG. 4, it can be confirmed that four peaks appear every 90 ° at the same position in both the MgIn ₂ O ₄ film and the Pt film. From this, it can be confirmed that both films are biaxially oriented in the plane, that is, it can be confirmed that both the MgIn ₂ O ₄ film and the Pt film are (002) -oriented epitaxial films.

FIG. 5 shows the addition of niobium in which part of Pb of lead titanate (PbTiO 3) as the ferroelectric film 20 is replaced with lanthanum (La) and further niobium is added on the lower electrode 32 of the structure 10X shown in FIG. 3 shows the result of X-ray diffraction (2θ-θ) measurement of a structure in which lead lanthanum titanate (PLMT) is formed. From FIG. 5, it can be confirmed that the ferroelectric film 20 formed on the structure 10X of FIG. 3 is strongly oriented in the (001) direction.

FIG. 6A is an exploded perspective view of the gyro sensor 100 according to the embodiment. The gyro sensor 100 includes a sensor element 101 having a tuning fork shape, a circuit board 100a electrically connected to the sensor element 101, a package 100b that houses the sensor element 101 and the circuit board 100a, and a lid 100c that covers the package 100b. have. The package 100b is made of an insulator such as ceramic or resin.

FIG. 6B is a plan view of the sensor element 101. By providing the intermediate film 40, the lower electrode 32d positioned below the

detection electrodes

31c and 31d and the ferroelectric film 20d provided on the lower electrode 32d become an (001) -oriented epitaxial film. Yes.

The sensor element 101 includes a base 110 and

arms

120 and 130 connected to the base 110. The sensor element 101 is obtained by processing the structure 10 including the ferroelectric film 20, the upper electrode 31, and the lower electrode 32 into the shape of a tuning fork vibrator. The base 110 and the

arms

120 and 130 are integrally formed by the structure 10. On the main surface 120S of the arm 120, a drive electrode 31a and a detection electrode 31c are formed. Similarly, on the main surface 130S of the arm 130, a drive electrode 31b and a detection electrode 31d are formed. These electrodes are obtained by etching the upper electrode 31 into a predetermined electrode shape. The lower electrode 32 formed on the main surfaces 120S and 130S of the base 110 and the

arms

120 and 130 functions as a ground electrode of the sensor element 101.

FIG. 6C is a cross-sectional view taken along line 6C-6C of the sensor element 101 shown in FIG. 6B. In the sensor element 101, the ferroelectric film 20d of the PZT film in the detection portion located under the detection electrode 31d is an epitaxial film. The ferroelectric film 20b of the PZT film in the driving portion located under the driving electrode 31b is an oriented ferroelectric film. In addition, the lower electrode under the oriented ferroelectric film 20b is (111) oriented, whereby the ferroelectric film 20b becomes an oriented film.

The sensor in which the ferroelectric film 20d of the PZT film in the detection portion is an epitaxial film and the ferroelectric film 20b of the PZT film in the driving portion is an oriented ferroelectric film is not limited to the angular velocity sensor. For example, the present invention can be applied to a vibration type acceleration sensor or a pyroelectric sensor.

FIG. 7A is a schematic sectional view of the pyroelectric sensor 200 in the embodiment.

The pyroelectric sensor 200 includes a pyroelectric sensor element 201, a package 200a that houses the pyroelectric sensor element 201, and a lens 200b.

FIG. 7B is a perspective view of the pyroelectric sensor element 201. FIG. 7C is a top view of the pyroelectric sensor element 201. 7D is a cross-sectional view of pyroelectric sensor element 201 taken along line 7D-7D shown in FIG. 7C.

The pyroelectric sensor element 201 includes a base 110, an arm 120 connected to the base 110, an arm 130 connected to the base 110, and a movable part 60 connected to the

arms

120 and 130.

When a voltage is applied to the

drive electrodes

31a and 31b, the movable part 60 vibrates, and the ferroelectric film 20d, which is an epitaxial film located under the detection electrode 31d provided on the movable part 60, is scanned to scan the infrared rays or the like. Light that changes the temperature of the ferroelectric film 20d can be detected. Thus, the pyroelectric sensor element 201 functions as a scanning pyroelectric sensor element.

As described above, the detection part, the drive part, and the film configuration are different. Thereby, the accuracy of the pyroelectric sensor 200 can be improved.

FIG. 8A is a top view of another pyroelectric sensor element 201a in the embodiment. FIG. 8B is a cross-sectional view of the pyroelectric sensor element 201a shown in FIG. 8A taken along line 8B-8B. 8C to 8G are cross-sectional views illustrating a manufacturing process of the pyroelectric sensor element 201a.

The pyroelectric sensor element 201a includes a substrate 52, a metal film 31p, a ferroelectric film 20d, a drive electrode 31b, and a detection electrode 31d. The metal film 31p is composed of a metal film (upper electrode 31) and a metal film 54 stacked on each other. The ferroelectric film 20d is an epitaxial film.

The substrate 52 is made of a material that is hardly soluble or insoluble in hydrochloric acid, such as stainless steel, or is otherwise made of a material having a significantly different etching rate from MgIn ₂ O ₄ that is the material of the intermediate film 40. An epitaxial film cannot be formed.

The metal film 31p is a metal film made of a material such as gold that is insoluble in a strong acid such as hydrochloric acid.

8C to 8G are diagrams for explaining a manufacturing process of the pyroelectric sensor element 201a.

As shown in FIG. 8C, the structure 10 includes a substrate 50, an intermediate film 40, a lower electrode 32, a ferroelectric film 20d, and an upper electrode 31. The intermediate film 40 may be described as a first layer, the lower electrode 32 as a second layer, and the ferroelectric film 20d as a third layer. The intermediate film 40 is made of MgIn ₂ O ₄ or ZnIn ₂ O ₄ .

As shown in FIG. 8D, the structure 10 is patterned leaving the substrate 50 to obtain the structure 10b. Here, the shape of the patterned structure 10b in the top view is the same as the shape of the

drive electrodes

31a and 31b and the detection electrode 31d shown in FIG. 8A in the top view. Specifically, here, the structure 10 includes an intermediate film 40, a lower electrode 32, a ferroelectric film 20 d, and an upper electrode 31.

Then, as shown in FIG. 8E, the patterned structure 10b is bonded to the substrate 52 patterned in the same shape as the patterned structure 10b to obtain the structure 10c shown in FIG. 8F. Specifically, a metal film 54 made of gold or the like is provided on the substrate 52, and metal bonding, solid phase diffusion bonding, ultrasonic bonding, or the like is performed with the upper electrode 31 of the structure 10b on which the metal film 54 is patterned. To be joined.

Thereafter, as shown in FIG. 8G, the structure 10 c is immersed in the strong acid 91. In the embodiment, the strong acid 91 is hydrochloric acid. Here, the upper electrode (for example, gold), the piezoelectric film (for example, PZT), the lower electrode (for example, platinum), and the substrate 52 (for example, SUS) are insoluble in hydrochloric acid that is the strong acid 91. On the other hand, MgIn ₂ O ₄ and ZnIn ₂ O ₄ used as the intermediate film 40 of the pyroelectric sensor element 201 a are soluble in hydrochloric acid, which is the strong acid 91. For this reason, the intermediate film 40 is removed by immersing the structure 10c in the strong acid 91, and as a result, the substrate 50 is peeled from the structure 10c.

In this way, the pyroelectric sensor element 201a shown in FIG. 8A is formed. That is, the ferroelectric film 20d, which is an epitaxial film patterned on the substrate 50, can be transferred to another substrate. In particular, a patterned ferroelectric film 20d can be provided on a substrate such as SUS on which a ferroelectric film 20d that is an epitaxial film cannot be directly formed.

FIG. 9A is a top view of the pyroelectric sensor element 201b1 in the embodiment. 9B is a cross-sectional view of pyroelectric sensor element 201b1 taken along line 9B-9B shown in FIG. 9A.

The pyroelectric sensor element 201b1 includes a substrate 50, an intermediate film 40, a ferroelectric film 20, an upper electrode 31, a contact portion 31e, a wiring 31f, a lower electrode 32, an insulating film 206a, and an insulating film 206b. And a cavity 208. Intermediate layer 40 is MgIn ₂ O ₄ film made MgIn ₂ O _4. The intermediate layer 40 may be a ZnIn ₂ O ₄ film made ZnIn ₂ O _4.

As the insulating film 206a, an insulator such as a silicon nitride film (SiN film), a silicon oxide film (SiO film), or a silicon oxynitride film (SiON film) can be used. The insulating film 206a supports a structure such as the ferroelectric film 20 and the upper electrode 31 on the substrate 50, or has a function of adjusting stress in the structure.

As the insulating film 206b, an insulator such as a silicon nitride film (SiN film), a silicon oxide film (SiO film), a silicon oxynitride film (SiON film), a polyimide-based permanent resist, or the like can be used. The insulating film 206b supports a structure such as the ferroelectric film 20 and the upper electrode 31 on the substrate 50, or has a function of insulating between the electrodes.

The ferroelectric film 20 is an ferroelectric film 20d that is an epitaxial film, an oriented ferroelectric film 20b, or the like. When used for a pyroelectric sensor element, the ferroelectric film 20 may be described as a pyroelectric film or a pyroelectric material.

The upper electrode 31 is a metal thin film made of titanium, platinum, gold or the like. Since the upper electrode 31 preferably has a certain sheet resistance, it is preferable to reduce the film thickness. For example, the film thickness of the upper electrode 31 is 10 nm. In the pyroelectric sensor element, the upper electrode 31 can be described as an infrared absorption film that absorbs infrared rays.

The wiring 31f is electrically connected to the upper electrode 31 and connected to the electrode 31g1. The wiring 31 f is arranged so as to surround the ferroelectric film 20. The electrode 31g2 is used for taking out an electric signal from the lower electrode 32.

The contact portion 31e is a connection portion where the upper electrode 31 and the wiring 31f are connected.

The cavity 208 is provided at least at a position below the ferroelectric film 20 and between the substrate 50 and the lower electrode 32. The cavity 208 is formed by removing the MgIn ₂ O ₂ film that can be selectively etched by wet etching. Therefore, both ends (side walls) of the cavity 208 are made of MgIn ₂ O ₂ . That is, the cavity 208 has an upper surface 208a, a lower surface 208b, and side surfaces 208c and 208d connected to the upper surface 208a and the lower surface 208b. The side surfaces 208 c and 208 d face each other through the cavity 208. Side surfaces of the

cavity

208 and 208c and 208d are made of MgIn ₂ O ₂ . Thus, the intermediate film 40 includes MIn ₂ O ₄ with M as a metal element of either Mg or Zn. The composition of the side surfaces 208c and 208c of the cavity 208 has the chemical formula MIn ₂ O ₄ . Further, since the thickness of the MgIn ₂ O ₂ film is, for example, 20 mm, the thickness of the cavity 208 is also 20 mm. On the other hand, the thickness of the lower electrode 32 is, for example, 1000 mm. Therefore, the thickness of the cavity 208 is smaller than the thickness of the lower electrode 32. A part of the upper surface constituting the cavity 208 becomes an insulating film 206a. However, after the cavity 208 is formed, the substrate 50 may be further etched using, for example, fluorine gas, thereby further expanding the cavity 208.

The vertical width of the cavity 208 is smaller than the vertical thickness of the lower electrode 32. A part of the upper surface 208a of the cavity 208 is composed of an insulating film 206b.

In the conventional pyroelectric sensor, the silicon substrate on the back side of the pyroelectric sensor element is etched to reduce the heat capacity of the pyroelectric sensor element and prevent the escape of heat. However, this method has problems such as time-consuming cavity processing or an increase in the size of the pyroelectric sensor element. On the other hand, in the pyroelectric sensor element 201b1, the intermediate film 40 is a MgIn ₂ O ₂ film that can be selectively etched, and this is selectively removed by wet etching, which is necessary for the conventional pyroelectric sensor. No cavity processing is required, and the pyroelectric sensor can be reduced in size.

The sheet resistance of the upper electrode 31 is desirably 250Ω to 500Ω in order to increase the amount of infrared rays absorbed by the pyroelectric film. If the sheet resistance of the upper electrode 31 using Pt (platinum) or Au (gold) is to be set to, for example, 250Ω to 500Ω, the film thickness becomes 1 nm or less because the specific resistance is small, and the film thickness (film thickness) controllability. Decreases. Alternatively, even when the upper electrode 31 using NiCr is intended to have a sheet resistance of 250 Ω to 500 Ω, the film thickness of the upper electrode 31 is 1.6 nm, and the controllability of film formation (film thickness) is lowered. Alternatively, if the sheet resistance of the upper electrode 31 is made to be 250 Ω to 500 Ω using a material having a large specific resistance such as Ti and Cr, Ti and Cr easily oxidize with heat because they are easily bonded to oxygen, and are reliable. It is difficult to keep sex. Therefore, it is preferable to use NiCrAlSi as the material of the upper electrode 31. The upper electrode 31 made of NiCrAlSi, that is, the NiCrAlSi electrode has a large specific resistance, so that the film thickness can be increased, the film thickness controllability and heat resistance are excellent, and the cost is lower than that of Pt or Au. Specifically, in the NiCrAlSi electrode, the weight ratio of Ni to Cr is 45/55 to 55/45, Al is contained in an amount of 10 to 18% by weight, and Si is contained in an amount of 2 to 6% by weight of the total weight. It is desirable to make it.

Alternatively, the upper electrode 31 may be formed of a material other than Si, which is easy to bond with oxygen and has high reliability. For example, the upper electrode 31 may be formed of Ta, Nb, Zr, Y, or Ti. The upper electrode 31 contains four elements of Ni, Cr, Al, and Si, has a higher resistance value than Ni, Cr, and Al alloy, has a sheet resistance of 250Ω to 500Ω, and a thickness of 5 nm or more.

FIG. 9C is a cross-sectional view of another pyroelectric sensor element 201b2 in the embodiment.

The pyroelectric sensor element 201b2 includes a substrate 50 different from the pyroelectric sensor element 201b1.

The substrate 50 has a laminated structure of films containing silicon. Specifically, the substrate 50 includes a silicon film (Si film) 50b1, a silicon oxide film (SiOx film) 50b2, a silicon nitride film (SiN film) 50b3, and a silicon oxide film (SiOx film) 50b4. The membrane 408 includes a silicon film (Si film) 50b1, a silicon oxide film (SiOx film) 50b2, a silicon nitride film (SiN film) 50b3, and a silicon oxide film (SiOx film) 50b4.

As shown in FIG. 9C, the substrate 50 used for the pyroelectric sensor element in the embodiment may not have the cavity 208 formed by etching the intermediate film 40 (MgIn ₂ O ₂ film).

In the cross section of the pyroelectric sensor elements 201b1 and 201b2, the portion where the ferroelectric film 20 exists functions as the light receiving portion 404. The same applies to other pyroelectric sensor elements in the embodiment.

In the cross section of the pyroelectric sensor element 201b1, a portion where the cavity 208 does not exist is a frame 406. In other words, the frame 406 is a portion where the substrate 50 and the intermediate film 40 exist. In the pyroelectric sensor element 201b2, the frame 406 is a portion where the Si film 50b1 exists. The same applies to other pyroelectric sensor elements in the embodiment.

The membrane 408 is a part where the cavity 208 exists in the cross section of the pyroelectric sensor element 201b1, and in another expression, the part where the intermediate film 40 does not exist. In the pyroelectric sensor element 201b2, the membrane 408 is a portion where the Si film 50b1 does not exist. In other words, the substrate 50 has a first portion and a second portion that is thinner than the first portion. In the pyroelectric sensor element 201b2 shown in FIG. 9C, the first part is the part of the Si film 50b1, and the second part is the SiOx film 50b2, the SiN film 50b3, the SiOx film 50b4 in the part where the Si film 50b1 does not exist. Is the combined part. In the pyroelectric sensor element 201b1 shown in FIG. 9A, the first portion is a portion where the intermediate film 40 and the substrate 50 are combined, and the second portion is where the intermediate film 40 is present. It is the board | substrate 50 in the part which is not carried out. This second part is the membrane 408. The same applies to other pyroelectric sensor elements in the embodiment.

FIG. 9D shows the characteristics of the pyroelectric sensor element 201b2. The pyroelectric coefficient of the ferroelectric film 20 changes according to the thickness of the membrane 408. That is, by setting the thickness of the membrane 408 to a certain value or less, the pyroelectric coefficient of the ferroelectric film 20 is increased, and as a result, the performance of the pyroelectric sensor element 201b2 can be improved. The mechanism by which this effect appears will be described. First, as the thickness of the SiOx film 50b4 decreases, the overall thickness of the membrane 408 decreases. And the restraining force from the membrane 408 of the ferroelectric film 20 decreases. As a result, since the polarization of the ferroelectric film 20 is easily aligned, the amount of polarization of the ferroelectric film 20 increases, the ferroelectricity increases, the pyroelectricity increases, and the pyroelectric coefficient increases. To do. An increase in pyroelectric coefficient results in an increase in output voltage, that is, sensor sensitivity, and as a result, the accuracy of the sensor can be improved. In particular, it has been confirmed through experiments that the effect can be obtained when the film thickness of the membrane 408 is 800 nm or less with respect to the film thickness of the ferroelectric film 20 of 1400 nm. Therefore, the film thickness of the membrane 408 is preferably 0.57 times (= 800 nm / 1400 nm) or less than the thickness of the ferroelectric film 20.

The conventional sensor of the above art is insufficient to meet the increasing demand for high accuracy and high reliability.

The pyroelectric sensor element 201b2 in the embodiment can obtain high accuracy as described above.

FIG. 10A is a top view of still another pyroelectric sensor element 201c1 in the embodiment. 10B is a cross-sectional view of pyroelectric sensor element 201c1 shown in FIG. 10A taken along line 10B-10B. FIG. 10C is an enlarged view of the pyroelectric sensor element 201c1 shown in FIG. 10B.

The pyroelectric sensor element 201c1 further includes a laminated film 210 in addition to the pyroelectric sensor element 201b1. The laminated film 210 is provided in the recess 212. The recess 212 has a bottom made of a portion of the upper electrode 31 in contact with the ferroelectric film 20 and a side wall made of the insulating film 206b.

The upper surface S1 of the laminated film 210 is lower than the upper surface S2 of the recess 212. In other words, the upper surface S1 of the stacked film 210 is lower than the upper surface S2 of the insulating film 206b. In other words, the thickness of the laminated film 210 is smaller than the depth of the recess 212.

The upper surface S1 of the laminated film 210 is higher than the upper surface S3 of the wiring 31f.

The laminated film 210 is a band-pass filter that transmits light of a predetermined wavelength band including the center wavelength of infrared light and does not transmit light having a wavelength other than the wavelength band, and has a function of transmitting only a specific wavelength. In an infrared sensor, only infrared rays having a desired wavelength can be transmitted. Here, it is preferable to use a silicon nitride film (SiN film) as a film constituting the laminated film because it functions as a moisture-resistant film and can serve as both a bandpass filter and a moisture-resistant film.

The laminated film 210 is provided on the upper surface of the film 210a provided on the upper surface of the upper electrode 31, the film 210b provided on the upper surface of the film 210a, the film 210c provided on the upper surface of the film 210b, and the upper surface of the film 210c. A film 210d.

The film 210a is made of a material having a high refractive index, and for example, ZrO ₂ , TiO ₂ , Nb ₂ O ₅ , or Ta ₂ O ₅ can be used.

The film 210b is made of a material having a lower refractive index than the film 210a, and for example, SiO ₂ or MgF ₂ can be used.

The film 210c is configured using the same material as the film 210a. The film 210d is formed using the same material as the film 210b. That is, the laminated film 210 is a structure in which a film made of a material having a high refractive index and a film made of a material having a low refractive index are alternately laminated. In the present embodiment, the laminated film 210 is described as a laminated structure of four films, but is not limited to this, and may be formed of five or more films, or may be formed of three or less films. May be.

A conventional pyroelectric sensor for detecting a specific wavelength includes a package, a bandpass filter bonded to the package, and a pyroelectric sensor element accommodated in the package. Thus, since the bandpass filter is a separate body from the pyroelectric sensor element, the pyroelectric sensor is increased in cost and size. In contrast, the pyroelectric sensor element 201c1 in the embodiment can be reduced in cost and size because the bandpass filter is integrated with the pyroelectric sensor element. Since the pyroelectric sensor element 201c1 is integrated with the band pass filter, it can function as a pyroelectric sensor without using the package 200a and the lens 200b shown in FIG. 7A. That is, the pyroelectric sensor element 201c1 may be described as a pyroelectric sensor.

FIG. 10D is an enlarged cross-sectional view of still another pyroelectric sensor element 201c2 in the embodiment. The pyroelectric sensor element 201c2 does not include the insulating film 206a.

In the pyroelectric sensor element 201c2, the laminated film 210 is provided in the recess 212. The recess 212 has a bottom made of a portion of the upper electrode 31 in contact with the ferroelectric film 20, and a side wall made of the wiring 31f and the contact portion 31e. The upper surface of the laminated film 210 is lower than the upper surface of the wiring 31f.

FIG. 10E is an enlarged cross-sectional view of still another pyroelectric sensor element 201c3 in the embodiment.

In the pyroelectric sensor element 201c3, the laminated film 210 is provided between the wiring 31f and the ferroelectric film 20. With this structure, the laminated film 210 functions as a protective film for the bandpass filter and the ferroelectric film 20, and also functions as an insulating film for the upper electrode 31 and the lower electrode 32. Thereby, manufacture of the pyroelectric sensor element 201c3 can be simplified.

In the pyroelectric sensor element 201c3, a part of the laminated film 210 covers the side surface S4 of the ferroelectric film 20. In other words, a part of the film 210a covers the side surface S4 of the ferroelectric film 20. Here, the thickness of the film 210a in the portion covering the side surface S4 of the ferroelectric film 20 is smaller than the thickness of the film 210a in the portion covering the upper surface of the ferroelectric film 20. A part of the film 210 a covers the upper surface of the lower electrode 32.

FIG. 10F is a top view of still another pyroelectric sensor element 201d in the embodiment. 10G is a cross-sectional view of pyroelectric sensor element 201d shown in FIG. 10F taken along line 10G-10G. The pyroelectric sensor element 201 d does not include the wiring 31 f surrounding the ferroelectric film 20. The other configuration of the pyroelectric sensor element 201d is the same as that of the pyroelectric sensor elements 201c1 to 201c3.

FIG. 11A is a top view of still another pyroelectric sensor element 201e in the embodiment. 11B is a cross-sectional view of pyroelectric sensor element 201e shown in FIG. 11A taken along line 11B-11B.

The pyroelectric sensor element 201e includes a substrate 50, an intermediate film 40, a ferroelectric film 20, an upper electrode 31, a contact portion 31g, a wiring 31f, a lower electrode 32, an insulating film 206a, and an insulating film 206b. And a cavity 208. Intermediate layer 40 is MgIn ₂ O ₄ film made MgIn ₂ O _4. Intermediate film 40 may be a ZnIn ₂ O ₄ film made ZnIn ₂ O _4.

As the insulating film 206a, an oxide film such as a silicon nitride film (SiN film), a silicon oxide film (SiO film), a silicon oxynitride film (SiON film), an Al ₂ O ₃ film, or a ZrO ₂ film is used. Can do. The insulating film 206a supports a structure such as the ferroelectric film 20 and the upper electrode 31 on the substrate 50, or has a function of adjusting a stress applied to the structure.

The insulating film 206b is a silicon nitride film (SiN film), a silicon oxide film (SiO film), a silicon oxynitride film (SiON film), an oxide film such as an Al ₂ O ₃ film, or a ZrO ₂ film, or polyimide A system permanent resist or the like can be used. The insulating film 206b has a function of supporting a concept such as the ferroelectric film 20 and the upper electrode 31 on the substrate 50 and insulating between the electrodes.

The ferroelectric film 20 is an ferroelectric film 20d that is an epitaxial film, an oriented ferroelectric film 20b, or the like.

The upper electrode 31 is a metal thin film made of titanium, platinum, gold or the like. Alternatively, a metal thin film using NiCrAlSi as described above. Since the upper electrode 31 preferably has a certain sheet resistance, it is preferable to reduce the film thickness. For example, the film thickness of the upper electrode 31 is 10 nm. Here, in the pyroelectric sensor element, the upper electrode 31 can also be described as an infrared absorption film that absorbs infrared rays.

The wiring 31f is electrically connected to the upper electrode 31 and connected to the electrode 31g1. The wiring 31 f is arranged so as to surround the ferroelectric film 20. Alternatively, the wiring 31f may be arranged so as to straddle one end portion of the ferroelectric film 20. The electrode 31g2 is used for taking out an electric signal from the lower electrode 32.

The cavity 208 is provided at least at a position below the ferroelectric film 20 and between the substrate 50 and the lower electrode 32. The cavity 208 is formed by removing a MgIn ₂ O ₂ film made of MgIn ₂ O _{2 that} can be selectively etched by wet etching. Therefore, both ends (side walls) of the cavity 208 are made of MgIn ₂ O ₂ . Further, since the thickness of the MgIn ₂ O ₂ film is, for example, 200 mm, the thickness of the cavity 208 is also 200 mm. On the other hand, the thickness of the lower electrode 32 is, for example, 1000 mm. Therefore, the thickness of the cavity 208 is smaller than the thickness of the lower electrode 32. A part of the upper surface constituting the cavity 208 is an insulating film 206a. However, after the cavity 208 is formed, the substrate 50 may be further etched using, for example, fluorine gas, thereby further expanding the cavity 208. Instead of the substrate 50 and the intermediate film 40, the substrate 50 of the pyroelectric sensor element 210b2 shown in FIG. 9C may be used.

In the pyroelectric sensor element 201e, a plurality of through holes 402 that penetrate from the lower surface of the membrane 408 to the upper surface of the membrane 408 are formed in the membrane 408. 11C to 11H are top views showing the shape of the through hole 402 in a top view. 11C to FIG. 11H show a direction D404 toward the light receiving unit 404 and a direction D406 away from the light receiving unit 404 and toward the frame 406.

The through hole 402 shown in FIG. 11C has a triangular shape when viewed from above. As a result, the cross-sectional area gradually decreases in the direction D404 from the frame 406 of the membrane 408 toward the light receiving portion 404, the thermal resistance increases, and the pyroelectric sensor element 201e output increases. In addition, the stress concentration applied to the membrane 408 is dispersed to improve the impact resistance. In FIG. 11C, the triangular apex is directed in the direction D406 toward the frame 406, but the triangular apex may be directed in the direction D404 toward the light receiving unit 404.

The through hole 402 shown in FIG. 11D has a triangular shape in a top view. Specifically, the plurality of through holes 402 include a plurality of through holes 402b1 having a triangular shape whose apex faces in the direction D406, and a plurality of through holes 402b2 having a triangular shape whose apex faces in the direction D404. Including. The plurality of through holes 402b1 are arranged symmetrically with respect to the plurality of through holes 402b2 with respect to the point Pb1 on the straight line Lb1. By arranging the through holes 402b1 and 402b2 having triangular shapes adjacent to each other symmetrically with respect to the point Pb1, it is possible to effectively improve the thermal insulation within a limited area.

In the top view, the plurality of through holes 402 have either a triangular shape or a trapezoidal shape, and are arranged symmetrically with respect to the plurality of through holes 402b1 forming the through hole group 4021 and the predetermined point Pb1 with respect to the through hole group 4021. And a plurality of through-holes 402b2 forming the through-hole group 4022.

The through-hole 402 shown in FIG. 11E has a trapezoidal shape having an upper base smaller than the lower bottom in a top view. Specifically, the plurality of through holes 402 include a plurality of through holes 402c1 having a trapezoidal shape with the upper base facing in the direction D406 and a plurality of through holes 402c2 having a trapezoidal shape with the lower bottom facing in the direction D404. Including. The plurality of through holes 402c1 are arranged symmetrically with respect to the plurality of through holes 402c2 with respect to the point Pc1 on the straight line Lc1. By arranging the through-holes 402c1 and 402c2 having triangular shapes adjacent to each other symmetrically with respect to the point Pc1, it is possible to effectively improve the thermal insulation within a limited area.

The through holes 402 shown in FIG. 11F are provided in a staggered pattern in a top view. As a result, it is possible to extend the distance through which heat is transmitted to the light receiving unit 404 and the frame 406, and to increase the thermal insulation and increase the output.

The through holes 402 shown in FIG. 11G have a rhombus shape arranged in a staggered pattern when viewed from above. As a result, the thermal insulation is further improved, and the shape of the membrane 408 connected to the light receiving portion 404 and the frame 406 becomes a triangular shape and the stress is dispersed to improve the impact resistance.

The through holes 402 shown in FIG. 11H have circular shapes arranged in a staggered pattern when viewed from above. As a result, the distance from the light receiving unit 404 to the frame 406 is increased, the thermal resistance is increased, and the output is increased.

The through holes 402 shown in FIGS. 11D and 11E are arranged as follows. The through hole 402 has a triangular shape or a trapezoidal shape when viewed from above. The through hole 402 includes a through hole 402b1 and a through hole 402b2 that are arranged point-symmetrically with respect to the straight line Lb1. The triangular apex of the through hole 402b1 faces the direction D406 opposite to the direction D404 in which the triangular apex of the through hole 402b2 faces. The through hole 402 includes a through hole 402c1 and a through hole 402c2 that are arranged point-symmetrically with respect to the straight line Lc1.

The through holes 402 shown in FIGS. 11C to 11H are arranged as follows. That is, the through hole 402 is provided so as to surround the light receiving unit 404. Here, “surround” means that the through-hole 402 is disposed in a belt-like region having a hollow square shape. Or the through-hole 402 is arrange | positioned at the area | region of a belt | band | zone (belt) which has a ring shape.

The through holes 402 shown in FIGS. 11C to 11H are arranged as follows. In other words, when the through hole 402 draws a straight line from the center of the light receiving portion 404 to the frame 406, at least a part of the straight line always passes through the through hole 402. For example, a straight line Ld1 from the center of the light receiving unit 404 to the frame 406 passes through the through hole 402 as shown in FIG. 11F, or an arbitrary line from the center of the light receiving unit 404 to the frame 406 as shown in FIG. 11F. The straight line passes through at least one of the plurality of through holes 402. Such a structure can also be described as “the through holes 402 are arranged in a staggered pattern (hound tooth check)”. That is, in the top view, the plurality of through holes 402 are arranged in a matrix shape having a plurality of columns C101 extending in the direction D101 and a plurality of rows C102 extending in the direction 102 intersecting the direction D101. The plurality of through holes 402 include a plurality of through holes 402d1 arranged in each row C101 of the plurality of rows C101, and a plurality of rows arranged in corresponding rows C101 adjacent to the respective rows C101 of the plurality of rows C101. Through-hole 402d2. When viewed from the direction D102, the boundary between the plurality of through holes 402d1 is deviated from the boundary between the plurality of through holes 402d2. As viewed from the direction D102, boundaries between the plurality of through holes 402d1 overlap with the plurality of through holes 402d2, and boundaries between the plurality of through holes 402d2 overlap with the plurality of through holes 402d1.

FIG. 12A is a top view of still another pyroelectric sensor element 201f in the embodiment. 12B is a cross-sectional view of pyroelectric sensor element 201f shown in FIG. 12A taken along line 12B-12B.

The pyroelectric sensor element 201f includes a substrate 50, an intermediate film 40, a ferroelectric film 20, an upper electrode 31, a contact portion 31g, a wiring 31f, a lower electrode 32, an insulating film 206a, and an insulating film 206b. And a cavity 208. The intermediate film 40 is a MgIn ₂ O ₄ film. The intermediate film 40 may be a ZnIn ₂ O ₄ film.

As the insulating film 206a, an oxide film such as a SiN film, a SiO film, a SiON film, an Al ₂ O ₃ film, or a ZrO ₂ film can be used. The insulating film 206a has a function of supporting a structure such as the ferroelectric film 20 and the upper electrode 31 on the substrate 50 or adjusting a stress applied to the structure.

As the insulating film 206b, an oxide film such as a SiN film, a SiO film, a SiON film, an Al ₂ O ₃ film, a ZrO ₂ film, a polyimide-based permanent resist, or the like can be used. The insulating film 206b has a function of supporting a structure such as the ferroelectric film 20 and the upper electrode 31 on the substrate 50 or insulating between the electrodes.

The ferroelectric film 20 is a ferroelectric film 20d that is an epitaxial film, or a ferroelectric film 20b that is made of an orientation.

The upper electrode 31 is a metal thin film made of titanium, platinum, gold or the like. Alternatively, a metal thin film using NiCrAlSi as described above. Since the upper electrode 31 preferably has a sheet resistance of a predetermined value or more, it is preferable to reduce the film thickness. For example, the film thickness of the upper electrode 31 is 10 nm. Here, the upper electrode 31 can also be described as an infrared absorption film.

The wiring 31f is electrically connected to the upper electrode 31 and connected to the electrode 31g1. The wiring 31 f is arranged so as to surround the ferroelectric film 20. Alternatively, the wiring 31 f may be arranged so as to straddle one end portion of the ferroelectric film 20. The electrode 31g2 is used for taking out an electric signal from the lower electrode 32.

The cavity 208 is provided at least at a position below the ferroelectric film 20 and between the substrate 50 and the lower electrode 32. The cavity 208 is formed by removing the MgIn ₂ O ₂ film that can be selectively etched by wet etching. Therefore, both ends (side walls) of the cavity 208 are made of MgIn ₂ O ₂ . Further, since the thickness of the MgIn ₂ O ₂ film is, for example, 200 mm, the thickness of the cavity 208 is also 200 mm. On the other hand, the thickness of the lower electrode 32 is, for example, 1000 mm. Therefore, the thickness of the cavity 208 is smaller than the thickness of the lower electrode 32. A part of the upper surface constituting the cavity 208 becomes an insulating film 206a. However, after the cavity 208 is formed, the substrate 50 may be further etched using, for example, fluorine gas, thereby further expanding the cavity 208. Instead of the substrate 50 and the intermediate film 40, the substrate 50 of the pyroelectric sensor element 201b2 shown in FIG. 9C may be used.

The light receiving portion 404 is a portion where the ferroelectric film 20 exists in the cross section of the pyroelectric sensor element 201f. The same applies to other pyroelectric sensor elements in the embodiment.

The frame 406 is a portion where the cavity 208 does not exist in the cross section of the pyroelectric sensor element 201f. In other words, the frame 406 is a portion where the substrate 50 and the intermediate film 40 exist. In other words, the frame 406 is a portion where the Si film 50b1 exists (see FIG. 9C). The same applies to other pyroelectric sensor elements in the embodiment.

The membrane 408 is a portion where the cavity 208 exists in the cross section of the pyroelectric sensor element 201f. In other words, the membrane 408 is a portion where the intermediate film 40 does not exist. In other words, the membrane 408 is a portion where the Si film 50b1 does not exist (FIG. 9B). In other words, the substrate 50 has a first portion and a second portion that is thinner than the first portion, and the second portion is the cavity 208. In the pyroelectric sensor element 201b2 shown in FIG. 9C, the first portion is a portion of the Si film 50b1, and the second portion is a portion of the SiOx film 50b2, SiN film 50b3, and SiOx film 50b4 where the Si film 50b1 does not exist. Is the combined part. In the pyroelectric sensor element 201c1 shown in FIG. 10A and FIG. 10B, the first portion is a portion where the intermediate film 40 where the intermediate film 40 exists is combined with the substrate 50, and the second portion is the intermediate film 40. This is the portion of the substrate 50 in which no exists. The same applies to other pyroelectric sensor elements in the embodiment.

FIG. 12C shows the characteristics of the pyroelectric sensor element 201f. One side of the light receiving unit 404 has a length Le, and one side of the membrane 408 has a length Lm. In the pyroelectric sensor element 201f, the ratio (Le / Lm) of the length Le to the length Lm is 0.8 or less. Thereby, the pyroelectric coefficient of the ferroelectric film 20 can be increased, and as a result, the output and sensitivity of the pyroelectric sensor element 201f can be increased. By reducing the ratio (Le / Lm), the size of the light receiving portion 404, that is, the ferroelectric film 20, is reduced with respect to the membrane 408, and the restraining force that the light receiving portion 404, that is, the ferroelectric film 20 receives from the membrane 408 is reduced. To do. For this reason, since the polarization during the polarization process of the ferroelectric film 20 is easily aligned, the pyroelectric coefficient of the ferroelectric film 20 increases, and the output voltage and sensitivity increase.

13A to 13E are enlarged views of the region P shown in FIGS. 9A, 10A, 10F, 11A, and 12A. In the region P, a contact portion in which the wiring 31f and the upper electrode 31 (light receiving portion 404) are in contact with each other is provided.

A configuration of the contact portion 501a shown in FIG. 13A will be described. In the top view of the pyroelectric sensor element 201b1, the lower electrode 32 is exposed from the upper electrode 31 by a gap G1. In order to connect the wiring 31f to the upper electrode 31, the insulating film 206a fills the gap G1. In FIG. 13A, the insulating film 206a is provided only in the vicinity of the wiring 31f, but this is not restrictive. That is, the insulating film 206a may cover the entire outer periphery of the upper electrode 31 (light receiving portion 404) in order to also protect the upper electrode 31 (light receiving portion 404). Thereby, since the ferroelectric film 20 can be protected from dust and moisture, the reliability is improved. It should be noted that the lower electrode 32 does not overlap the upper electrode 31 in a top view, in another expression, the lower electrode 32 is exposed from the upper electrode 31 in a top view, and the lower electrode 32 is exposed from the upper electrode 31 in a top view. The portion to be described is described as “the portion that does not overlap”. The wiring 31f passes over the insulating film 206a and is connected to the upper electrode 31. Accordingly, the wiring 31f has a step ST1 provided on the insulating film 206a.

A configuration of the contact portion 501b shown in FIG. 13B will be described. In the top view of the pyroelectric sensor element 201b1, the lower electrode 32 is exposed from the upper electrode 31 by a gap G1. In order to connect the wiring 31f to the upper electrode 31, the insulating film 206a fills the gap G1. In FIG. 13B, the insulating film 206a is provided only in the vicinity of the wiring 31f, but this is not restrictive. That is, the insulating film 206a may cover the entire outer periphery of the upper electrode 31 (light receiving portion 404) in order to also protect the upper electrode 31 (light receiving portion 404). Thereby, since the ferroelectric film 20 can be protected from dust and moisture, the reliability is improved. It should be noted that the lower electrode 32 does not overlap the upper electrode 31 in a top view, in another expression, the lower electrode 32 is exposed from the upper electrode 31 in a top view, and the lower electrode 32 protrudes from the upper electrode 31 in a top view. The portion may be described as “a portion that does not overlap”. The wiring 31f passes over the insulating film 206a and is connected to the upper electrode 31. Accordingly, the wiring 31f has a step ST2 provided on the insulating film 206a.

In the contact portion 501b shown in FIG. 13B, the wiring 31f has an overhang provided at the end thereof. In another expression, the wiring 31f has an H shape as a whole. In other words, the wiring 31f covers at least a part of the three sides of the insulating film 206a. In other words, the wiring 31f covers two corners of the insulating film 206a. With this configuration, since the wiring 31f can cover the step ST2 of the insulating film 206a from a plurality of directions (a plurality of surfaces), even if the wiring 31f is formed by sputtering or the like from one direction, the light receiving unit 404 ( It is possible to prevent a decrease in yield during the production of the pyroelectric sensor element due to the disconnection of the upper electrode 31). Furthermore, it is possible to improve the long-term reliability by reducing the probability that the light receiving unit 31 (upper electrode 404) is disconnected during operation of the pyroelectric sensor element. Note that when a film is formed by sputtering or the like, a metal film may be deposited from a specific biased direction with respect to the substrate due to a displacement of an apparatus used or the substrate. However, since the wiring 31f can cover the step of the insulating film 206a from a plurality of directions (a plurality of surfaces), it is possible to suppress a decrease in the reliability of the wiring even in such a situation.

A configuration of the contact portion 501c shown in FIG. 13C will be described. In the top view of the pyroelectric sensor element 201b1, the lower electrode 32 is exposed from the upper electrode 31 by a gap G1. In order to connect the wiring 31f to the upper electrode 31, the insulating film 206a fills the gap G1. In FIG. 13C, the insulating film 206a is provided only in the vicinity of the wiring 31f, but this is not restrictive. That is, the insulating film 206a may cover the entire outer periphery of the upper electrode 31 (light receiving portion 404) in order to also protect the upper electrode 31 (light receiving portion 404). Thereby, since the ferroelectric film 20 can be protected from dust and moisture, the reliability is improved. It should be noted that the lower electrode 32 does not overlap the upper electrode 31 in a top view, in another expression, the lower electrode 32 is exposed from the upper electrode 31 in a top view, and the lower electrode 32 protrudes from the upper electrode 31 in a top view. The portion may be described as “a portion that does not overlap”. The wiring 31f passes over the insulating film 206a and is connected to the upper electrode 31. Accordingly, the wiring 31f has a step ST3 provided on the insulating film 206a.

In the contact portion 501c shown in FIG. 13C, the wiring 31f has an overhang provided at the end thereof. In other words, the wiring 31f has a U-shape, that is, a U-shape as a whole. In other words, the wiring 31f covers at least a part of two sides of the insulating film 206a. In other words, the wiring 31f covers one corner of the insulating film 206a.

With this configuration, since the wiring 31f can cover the steps of the insulating film 206a from a plurality of directions (a plurality of surfaces), even if the wiring 31f is formed by sputtering or the like from one direction, the light receiving portion 404 (upper part) It is possible to prevent a decrease in yield during the production of the pyroelectric sensor element due to the disconnection of the electrode 2). Furthermore, it is possible to improve the long-term reliability by reducing the probability of disconnection of the light receiving unit 31 (upper electrode 404) during operation of the pyroelectric sensor element. Note that when a film is formed by sputtering or the like, a metal film may be deposited from a specific biased direction with respect to the substrate due to a displacement of an apparatus used or the substrate. However, since the wiring 31f can cover the steps of the insulating film 206a from a plurality of directions (a plurality of surfaces), it is possible to suppress a decrease in the reliability of the wiring even in such a situation.

A configuration of the contact portion 501d shown in FIG. 13D will be described. In the top view of the pyroelectric sensor element 201b1, the lower electrode 32 is exposed from the upper electrode 31 by a gap G1. In order to connect the wiring 31f to the upper electrode 31, the insulating film 206a fills the gap G1. In FIG. 13D, the insulating film 206a is provided only in the vicinity of the wiring 31f, but this is not restrictive. That is, the insulating film 206a may cover the entire outer periphery of the upper electrode 31 (light receiving portion 404) in order to also protect the upper electrode 31 (light receiving portion 404). Thereby, since the ferroelectric film 20 can be protected from dust and moisture, the reliability is improved. It should be noted that the lower electrode 32 does not overlap the upper electrode 31 in a top view, in another expression, the lower electrode 32 is exposed from the upper electrode 31 in a top view, and the lower electrode 32 protrudes from the upper electrode 31 in a top view. The portion may be described as “a portion that does not overlap”. The wiring 31f passes over the insulating film 206a and is connected to the upper electrode 31. Accordingly, the wiring 31f has a step ST4 provided on the insulating film 206a.

In the contact portion 501d shown in FIG. 13D, the wiring 31f has an overhang provided at the end thereof. In another expression, the wiring 31f has an H shape as a whole. Here, the side of the insulating film 206a has an arc shape in a top view, and the wiring 31f and its end portion pass over the arc-shaped side of the insulating film 206a.

With this configuration, since the wiring 31f can cover the steps of the insulating film 206a from a plurality of directions (a plurality of surfaces), even if the wiring 31f is formed by sputtering or the like from one direction, the light receiving portion 404 (upper part) It is possible to prevent a decrease in yield during the production of the pyroelectric sensor element due to the disconnection of the electrode 2). Furthermore, it is possible to improve the long-term reliability by reducing the probability of disconnection of the light receiving unit 31 (upper electrode 404) during operation of the pyroelectric sensor element. Note that when a film is formed by sputtering or the like, a metal film may be deposited from a specific biased direction with respect to the substrate due to a displacement of an apparatus used or the substrate. However, since the wiring 31f can cover the step ST4 of the insulating film 206a from a plurality of directions (a plurality of surfaces), a decrease in wiring reliability can be suppressed even in such a situation.

A configuration of the contact portion 501d1 illustrated in FIG. 13E will be described. In the contact portion 501d1 shown in FIG. 13E, the wiring 31f in the contact portion 501d shown in FIG. 13D has a U-shape that covers the sides SD2 and Sd4 in a top view like the wiring 31f in the contact portion 501c shown in FIG. 13C.

As described above, the light receiving unit 404 includes the upper surface 404A configured by the upper surface of the upper electrode 31 and the side surface 404B connected to the upper surface 404A (see FIGS. 11A and 13A to 13D). The insulating film 206a covers at least a part of the side surface 404B of the light receiving unit 404 and at least a part of the upper surface 404A. The insulating film 206a includes a portion 206a1 which is located above the light receiving portion 404 and has a shape having a plurality of sides SD1 to SD4 when viewed from above. The wiring 31f covers two or more sides SD2 and SD4 of the plurality of sides of the portion 206a1 of the insulating film 206a.

The portion 206a1 of the insulating film 206a has a rectangular shape having four sides SD1 to SD4 in a top view. The sides SD1 and SD3 are located on opposite sides, and the sides SD2 and SD4 are located on opposite sides.

The wiring 31f may cover a portion of the insulating film 206a and have an H-shaped portion in a top view (see FIG. 13B).

The wiring 31f may cover the portion 206a1 of the insulating film 206a and have a U-shaped portion (see FIG. 13C).

The lower electrode 32 has a portion (gap G1) exposed from the upper electrode 31 in a top view. The insulating film 206a covers the portion (gap G1) of the lower electrode 32.

The insulating film 206a may cover the portion (gap G1) of the lower electrode 32 so as to surround the light receiving portion 404 (see FIG. 13A).

One or more sides SD2 and Sd4 of the plurality of sides SD1 to SD4 of the portion 206a of the insulating film 206a may have an arc shape in a top view (see FIG. 13D).

13F and 13G are enlarged views of the region P shown in FIG. 11A. In the region P, a contact portion in which the wiring 31f and the upper electrode 31 (light receiving portion 404) are in contact with each other is provided.

A configuration of the contact portion 501e shown in FIG. 13F will be described. In the top view of the pyroelectric sensor element 201b1, the lower electrode 32 is exposed from the upper electrode 31 by a gap G1. In order to connect the wiring 31f to the upper electrode 31, the insulating film 206a fills the gap G1. In FIG. 13F, the insulating film 206a is provided only in the vicinity of the wiring 31f, but this is not restrictive. That is, the insulating film 206a may cover the entire outer periphery of the upper electrode 31 (light receiving portion 404) in order to also protect the upper electrode 31 (light receiving portion 404). Thereby, since the ferroelectric film 20 can be protected from dust and moisture, the reliability is improved. It should be noted that the lower electrode 32 does not overlap the upper electrode 31 in a top view, in another expression, the lower electrode 32 is exposed from the upper electrode 31 in a top view, and the lower electrode 32 protrudes from the upper electrode 31 in a top view. The portion may be described as “a portion that does not overlap”. The wiring 31f passes over the insulating film 206a and is connected to the upper electrode 31. Accordingly, the wiring 31f has a step ST5 provided on the insulating film 206a.

In the contact portion 501e shown in FIG. 13F, the insulating film 206a has a convex portion. The wiring 31f passes over the convex portion.

With this configuration, since the wiring 31f can cover the steps of the insulating film 206a from a plurality of directions (a plurality of surfaces), even if the wiring 31f is formed by sputtering or the like from one direction, the light receiving portion 404 (upper part) It is possible to prevent a decrease in yield when the pyroelectric sensor element is produced due to the disconnection of the electrode 31). Furthermore, it is possible to improve the long-term reliability by reducing the probability of disconnection of the light receiving unit 31 (upper electrode 404) during operation of the pyroelectric sensor element. Note that, when a film is formed by sputtering or the like, a metal film may be deposited from a specific biased direction with respect to the substrate due to an apparatus used or a positional deviation of the substrate. Since the step of the insulating film 206a can be covered from a plurality of directions (a plurality of surfaces), a decrease in the reliability of the wiring can be suppressed even in such a situation.

A configuration of the contact portion 501f shown in FIG. 13G will be described. In the top view of the pyroelectric sensor element 201b1, the lower electrode 32 is exposed from the upper electrode 31 by a gap G1. In order to connect the wiring 31f to the upper electrode 31, the insulating film 206a fills the gap G1. In FIG. 13G, the insulating film 206a is provided only in the vicinity of the wiring 31f, but this is not restrictive. That is, the insulating film 206a may cover the entire outer periphery of the upper electrode 31 (light receiving portion 404) in order to also protect the upper electrode 31 (light receiving portion 404). Thereby, since the ferroelectric film 20 can be protected from dust and moisture, the reliability is improved. It should be noted that the lower electrode 32 does not overlap the upper electrode 31 in a top view, in another expression, the lower electrode 32 is exposed from the upper electrode 31 in a top view, and the lower electrode 32 protrudes from the upper electrode 31 in a top view. The portion may be described as “a portion that does not overlap”. The wiring 31f passes over the insulating film 206a and is connected to the upper electrode 31. Accordingly, the wiring 31f has a step ST6 where it runs over the insulating film 206a.

In the contact portion 501f shown in FIG. 13G, the insulating film 206a has a hexagonal shape in a top view. The wiring 31f passes over the hexagonal apex.

With this configuration, since the wiring 31f can cover the steps of the insulating film 206a from a plurality of directions (a plurality of surfaces), even if the wiring 31f is formed by sputtering or the like from one direction, the light receiving portion 404 (upper part) It is possible to prevent a decrease in yield during fabrication of the pyroelectric sensor element due to disconnection of the electrode 31. Further, the probability of disconnection of the light receiving unit 31 (upper electrode 404) during operation of the pyroelectric sensor element is reduced, thereby improving long-term reliability. Note that, when a film is formed by sputtering or the like, a metal film may be deposited from a specific biased direction with respect to the substrate due to misalignment of an apparatus used or the substrate. However, since the wiring 31f can cover the step ST6 of the insulating film 206a from a plurality of directions (a plurality of surfaces), a decrease in the reliability of the wiring can be suppressed even in such a situation.

FIG. 14A is a schematic cross-sectional view of a gas sensor 300a in the embodiment.

The gas sensor 300a includes a pyroelectric sensor 200, a thermistor 302 that is a temperature detection unit that detects the temperature of the gas, a light source 304, and a circuit board 306. The circuit board 306 performs predetermined processing on the lighting control of the light source 304, the detection signal from the pyroelectric sensor 200, and the detection signal from the thermistor 302. The pyroelectric sensor 200 and the thermistor 302 are provided on one surface of the circuit board 306.

The light source 304 is provided at a position separated from the pyroelectric sensor 200 by a predetermined distance. An optical path 310 is provided between the light source 304 and the pyroelectric sensor 200. The light source 304 emits infrared rays toward the pyroelectric sensor 200. The light source 304 is, for example, a light source that emits infrared rays, such as a filament lamp, a miniature lamp, or an LED. The light source 304 is held by a support member 308 fixed to the circuit board 306. The light source 304 is controlled to blink at a predetermined cycle.

The cross section of the support member 308 has a semi-elliptical shape that is recessed in a direction away from the optical path 310. A mirror surface is formed inside the semi-elliptical shape. That is, the support member 308 is an elliptical mirror. The light source 304 is provided at the semi-elliptical focus of the support member 308. Therefore, infrared light emitted from the light source 304 passes through the optical path 310 and directly enters the pyroelectric sensor 200, or reflects off a mirror surface formed on the support member 308 and then passes through the optical path 310. Or incident on the pyroelectric sensor 200.

The lens 200b included in the pyroelectric sensor 200 has a function as an optical filter. In other words, the lens 200b is a band-pass filter that passes infrared rays in a predetermined wavelength band. The predetermined wavelength band is, for example, a wavelength band including the vicinity of 4.26 μm, which is an infrared wavelength having a high absorption rate by carbon dioxide molecules. In the predetermined wavelength band, when the concentration detection target is a gas other than carbon dioxide, the wavelength according to the type of gas that is the concentration detection target, that is, the absorption rate of the gas that is the concentration detection target is high. A wavelength band centered on the wavelength is selected. That is, the pyroelectric sensor 200 receives infrared rays having a predetermined wavelength band among infrared rays emitted from the light source 304 and does not receive light having a wavelength outside the wavelength band.

The thermistor 302 is provided around the pyroelectric sensor 200 and is fixed to the circuit board 306. In the thermistor 302, a constant current flows when a voltage is applied from the circuit board 306, and a voltage generated when the constant current flows is detected in the circuit board 306 as an output voltage.

The cover 312 is provided so as to cover the pyroelectric sensor 200, the thermistor 302, and the like, and is fixed to the circuit board 306. The cover 312 is provided with an inlet 314 for taking in gas from the outside of the cover 312 and discharging gas inside the cover 312. The intake port 314 is provided with an air filter.

The detection of the concentration of carbon dioxide by the gas sensor 300 a is performed in a state where gas is taken into the cover 312 from the intake port 314. When infrared rays are emitted from the light source 304 toward the pyroelectric sensor 200, the emitted infrared rays are received by the pyroelectric sensor 200. The pyroelectric sensor 200 outputs a voltage in response to infrared light reception. At this time, the output voltage varies depending on the concentration of carbon dioxide in the optical path 310. This is because the infrared ray radiated from the light source 304 is absorbed by the carbon dioxide on the optical path 310, so that the amount of infrared ray reaching the pyroelectric sensor 200 from the light source 304 also changes depending on the concentration of carbon dioxide.

Since the lens 200b transmits infrared rays having a wavelength with a high carbon dioxide absorption rate, the output from the pyroelectric sensor 200 can be converted into the concentration of carbon dioxide.

FIG. 12B is a schematic cross-sectional view of another gas sensor 300b according to the embodiment. In the gas sensor 300b, pyroelectric sensor elements 201c1 to 201c3 and 201d are used as the pyroelectric sensor 200. Thus, the gas sensor 300b does not include the package 200a and the lens 200b.

The “film” in the present embodiment is a “film” that is observed as a layered structure in the cross section of the sensor or sensor element.

In any pyroelectric sensor, the drive electrode, the ferroelectric layer below it, and the lower electrode are not essential. That is, none of the pyroelectric sensors needs to be a scanning type that drives the movable part.

In any sensor, the effect is obtained only when the PZT in the detection portion is the ferroelectric film 20d which is an epitaxial film and the film in the driving portion is the ferroelectric film 20b having orientation. Therefore, the ferroelectric film 20d which is the epitaxial film of the detection portion is not limited to the configuration shown in FIG.

Note that the characteristics of a sensor such as a gyro sensor or a pyroelectric sensor using the structure 10 using the ferroelectric film of the present embodiment can also be described as follows. The sensor includes a substrate 50, a lower electrode 32 provided on the substrate 50, a ferroelectric film 20 provided on the lower electrode 32, and an upper electrode 31 provided on the ferroelectric film 20. Here, the upper electrode 31 includes

drive electrodes

31a and 31b and

detection electrodes

31c and 31d. The distance from the substrate 50 to the

drive electrodes

31a and 31b, that is, the distance between the straight lines L0 and L1 shown in FIG. 6C is the distance from the substrate 50 to the

detection electrodes

31c and 31d, that is, the straight lines L0 and L2 shown in FIG. Less than the distance between.

The structure 10 includes the substrate 50, the intermediate film 40, the lower electrode 32, the ferroelectric film 20, and the upper electrode 31, but is not limited thereto. By using a functional film having characteristics such as an ion conductive film, a thermoelectric conversion film, a magnetic film, and a semiconductor film instead of the ferroelectric film, the function of each film can be improved. That is, the structure according to the present embodiment includes the substrate 50, the intermediate film 40, and the lower electrode 32. In this structure, for example, the lower electrode 32 having orientation can be used as a catalyst.

Note that the ferroelectric film 20 of any pyroelectric sensor element may be a piezoelectric film made of PZT or the like.

In addition, the through-hole 402 having a plurality of shapes among various shapes shown in FIGS. 11C to 11H may be provided in the membrane 408 of one final power sensor element.

In all the drawings, configurations not necessary for explanation may be omitted.

In the embodiment, terms indicating directions such as “upper surface”, “lower surface”, and “upward” indicate relative directions determined by the relative positional relationship of the constituent members of the pyroelectric sensor element, and are absolute such as the vertical direction. It does not indicate a correct direction.

Since the pyroelectric sensor element of the present invention and the pyroelectric sensor using the same can improve accuracy and reliability, they are useful for electronic devices and vehicle control.

DESCRIPTION OF SYMBOLS 10 Structure 10b Structure 10c Structure 20 Ferroelectric film 20d Ferroelectric film 20b Ferroelectric film 31

Upper electrode

31a,

31b Drive electrode

31c, 31d Detection electrode 31e Contact part 31f Wiring 31g1,

31g2 Electrode

32, 32d Lower part Electrode 40 Intermediate film 50 Substrate 50b1 Silicon film (Si film)
50b2 Silicon oxide film (SiOx film)
50b3 Silicon nitride film (SiN film)
50b4 Silicon oxide film (SiOx film)
52 Substrate 54 Metal film 60 Movable part 100 Gyro sensor 101 Sensor element 100a Circuit board 100b Package 100c Lid 110

Base part

120, 130 Arm 200 Pyroelectric sensor 200a

Package 200b Lens

201, 201a, 201b1, 201b2, 201c1 to 201c3, 201d, 201e , 201f Pyroelectric sensor element 206a Insulating film 206b Insulating film 208 Cavity 210 Laminated film 210a Film 210b Film 210c Film 210d Film 212

Recess

300a, 300b Gas sensor 302 Thermistor 304 Light source 306 Circuit board 308 Support member 310 Optical path 312 Cover 314 Intake 402 Through Hole 404 Light receiving portion 406 Frame 408 Membrane 501a to 501f Contact portion

Claims

A substrate having a first portion and a second portion thinner than the first portion;
A membrane provided on the upper surface of the substrate, including a lower electrode and having an upper surface from which the upper surface of the lower electrode is exposed;
A ferroelectric film provided on the upper surface of the lower electrode;
An upper electrode provided on the upper surface of the ferroelectric film;
With
The membrane is provided with a plurality of through holes penetrating from the lower surface of the membrane to the upper surface of the membrane at a position overlapping the second portion of the substrate in a top view,
The pyroelectric sensor element, wherein the plurality of through holes are arranged in a belt-like region having a ring shape surrounding the ferroelectric film in a top view.
The pyroelectric sensor element according to claim 1, wherein the plurality of through holes are provided symmetrically with respect to two axes that pass through the center of the substrate and are orthogonal to each other.
The pyroelectric sensor element according to claim 1, wherein the plurality of through holes have a triangular shape, a trapezoidal shape, a circular shape, an elliptical shape, or a rhombus shape when viewed from above.
The pyroelectric sensor element according to claim 1, wherein the plurality of through holes have a circular shape, an elliptical shape, or a rhombus shape in a top view, and are arranged in a staggered pattern.
When viewed from above, the plurality of through holes are arranged in a matrix shape having a plurality of columns extending in a first direction and a plurality of rows extending in a second direction intersecting the first direction,
The plurality of through holes are a plurality of first through holes arranged in each of the plurality of rows and a plurality of first holes arranged in corresponding rows adjacent to the respective rows of the plurality of rows. Two through holes,
2. The pyroelectric sensor element according to claim 1, wherein a boundary between the plurality of first through holes is shifted from a boundary between the plurality of second through holes when viewed from the second direction.
When viewed from above, the plurality of through holes have either a triangular shape or a trapezoidal shape, the plurality of first through holes forming the first through hole group, and the first through hole group at a predetermined point. The pyroelectric sensor element according to claim 1, further comprising a plurality of second through holes forming a second through hole group arranged symmetrically with respect to each other.
The pyroelectric sensor element according to claim 1, wherein a width of the ferroelectric film is 0.8 times or less of a width of the second portion of the substrate.
2. The membrane according to claim 1, wherein the membrane includes the first silicon oxide film, a silicon nitride film, and a second silicon oxide film that is farther from the ferroelectric film than the first silicon oxide film. Pyroelectric sensor element.
The pyroelectric sensor element according to claim 8, wherein the thickness of the membrane is 0.57 times or less the thickness of the ferroelectric film.
The first portion of the substrate is bonded to the lower surface of the membrane;
The pyroelectric sensor element according to claim 1, wherein a cavity facing the lower surface of the membrane and an upper surface of the second portion of the substrate is provided on the upper surface of the substrate.
A substrate having a first portion and a second portion thinner than the first portion;
A membrane provided on the upper surface of the substrate, including a lower electrode and having an upper surface from which the upper surface of the lower electrode is exposed;
A ferroelectric film provided on the upper surface of the lower electrode;
An upper electrode provided on the upper surface of the ferroelectric film;
With
The membrane is provided with a plurality of through holes penetrating from the lower surface of the membrane to the upper surface of the membrane at a position overlapping the second portion of the substrate in a top view,
The pyroelectric sensor element in which the plurality of through holes are in a triangular shape, an elliptical shape, or a rhombus shape in a top view, and are arranged in a staggered pattern.
When viewed from above, the plurality of through holes are arranged in a matrix shape having a plurality of columns extending in a first direction and a plurality of rows extending in a second direction intersecting the first direction,
The plurality of through holes are a plurality of first through holes arranged in each of the plurality of rows and a plurality of first holes arranged in corresponding rows adjacent to the respective rows of the plurality of rows. Two through holes,
The pyroelectric sensor element according to claim 11, wherein a boundary between the plurality of first through holes is shifted from a boundary between the plurality of second through holes when viewed from the second direction.
The pyroelectric sensor element according to claim 11, wherein the plurality of through holes are arranged in a belt-shaped region having a ring shape surrounding the ferroelectric film in a top view.
The pyroelectric sensor element according to claim 11, wherein a width of the ferroelectric film is equal to or less than 0.8 times a width of the second portion.
12. The membrane according to claim 11, wherein the membrane includes the first silicon oxide film, a silicon nitride film, and a second silicon oxide film that is further away from the ferroelectric film than the first silicon oxide film. Pyroelectric sensor element.
The pyroelectric sensor element according to claim 15, wherein the thickness of the membrane is 0.57 times or less the thickness of the ferroelectric film.
The first portion of the substrate is bonded to the lower surface of the membrane;
The pyroelectric device according to any one of claims 11 to 16, wherein a cavity facing the lower surface of the membrane and an upper surface of the second portion of the substrate is provided on the upper surface of the substrate. Sensor element.
A substrate having a first portion and a second portion thinner than the first portion;
A membrane provided on the upper surface of the substrate, including a lower electrode and having an upper surface from which the upper surface of the lower electrode is exposed;
A ferroelectric film provided on the upper surface of the lower electrode;
An upper electrode provided on the upper surface of the ferroelectric film;
With
The membrane is provided with a plurality of through holes penetrating from the lower surface of the membrane to the upper surface of the membrane at a position overlapping the second portion of the substrate in a top view,
When viewed from above, the plurality of through holes have either a triangular shape or a trapezoidal shape. The plurality of first through holes forming the first through hole group and the first through hole group with respect to a predetermined point. A pyroelectric sensor element including a plurality of second through holes forming a second through hole group arranged symmetrically with respect to each other.
The pyroelectric sensor element according to claim 18, wherein a direction in which tips of the plurality of first through holes are directed is opposite to a direction in which tips of the plurality of second through holes are directed.
The pyroelectric sensor element according to claim 18, wherein the plurality of through holes are arranged in a belt-like region having a ring shape surrounding the ferroelectric film in a top view.
The pyroelectric sensor element according to claim 18, wherein a width of the ferroelectric film is 0.8 times or less of a width of the second portion.
19. The membrane according to claim 18, wherein the membrane includes the first silicon oxide film, a silicon nitride film, and a second silicon oxide film that is further away from the ferroelectric film than the first silicon oxide film. Pyroelectric sensor element.
The pyroelectric sensor element according to claim 22, wherein the thickness of the membrane is 0.57 times or less the thickness of the ferroelectric film.
The first portion of the substrate is bonded to the lower surface of the membrane;
The pyroelectric sensor element according to claim 18, wherein a cavity facing the lower surface of the membrane and an upper surface of the second portion of the substrate is provided on the upper surface of the substrate.
Pyroelectric sensor element according to any one of claims 1 to 24;
A package containing the pyroelectric sensor element;
A lens provided in the package;
Pyroelectric sensor with