JP2014095674A - Infrared detector and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared detector and a manufacturing method thereof capable of increasing the sensitivity while reducing the cost.SOLUTION: An infrared detector 1 includes: an infrared detection element 10 which has plural pyroelectric elements 11 mounted on a board 18; a signal processing unit 20 that processes signals output from the infrared detection element 10; and a package 30 storing the infrared detection element 10 and the signal processing unit 20. Each of the pyroelectric elements 11 includes one light receiving part 13, a first output terminal 16 and a second output terminal 17 which are electrically connected to the light receiving part 13. Each of the light receiving part 13 is constituted of a first electrode 14 and a second electrode 15, which are formed at the front side and the rear side of the pyroelectric substrate 12 respectively being opposite to each other, and a portion 12a sandwiched by the first electrode 14 and the second electrode 15 in the pyroelectric substrate 12. In each of the light receiving parts 13, the thickness of the first electrode 14 is thinner than the thickness of the second electrode 15.

Description

  The present invention relates to an infrared detector having a pyroelectric element and a method for manufacturing the same.

  Pyroelectric elements are widely used in infrared detectors such as human body detection sensors that detect the movement of a human body. The pyroelectric element is an element that detects infrared rays by the pyroelectric effect. The pyroelectric effect is a phenomenon in which charges are generated on the surface due to temperature changes. When the infrared rays are incident on the pyroelectric element in an equilibrium state where the charge due to spontaneous polarization is neutralized by ions in the outside air, the infrared rays are converted into heat, and the temperature of the pyroelectric substrate changes. The charge balance is broken and charges are generated on the surface of the pyroelectric substrate.

  As an infrared detector, one in which a pyroelectric element and parts of a circuit for processing an output signal of the pyroelectric element are accommodated in one package is widely known.

  As a pyroelectric element, a dual element (dual type pyroelectric element) in which two light receiving portions are formed on one pyroelectric substrate, or four light receiving portions are formed on one pyroelectric substrate. Quad elements (quad type pyroelectric elements) are widely known.

As a material for the pyroelectric substrate, for example, a single crystal material such as lithium tantalate (LiTaO ₃ ) or lithium niobate (LiNbO ₃ ) is employed. In addition, the light receiving unit includes two pairs of electrodes that are formed on both sides in the thickness direction of the pyroelectric substrate and face each other, and a portion sandwiched between the two pairs of electrodes on the pyroelectric substrate. ing. NiCr or the like is adopted as a material for each electrode. NiCr is a material that has conductivity and can absorb infrared rays.

  In this type of pyroelectric element, a plurality of light receiving portions are formed at the center of the pyroelectric substrate, output terminal portions are formed at both ends of the pyroelectric substrate, and both sides of the pyroelectric substrate in the thickness direction are formed. Each is formed with a wiring portion for connecting the electrode of the light receiving portion and the output terminal portion (for example, Patent Documents 1 and 2).

  The pyroelectric element (infrared detecting element) disclosed in Patent Document 1 employs NiCr as a material for the electrode of the light receiving portion, the output terminal portion, and the wiring portion.

  Patent Document 2 relates to a method for manufacturing a pyroelectric element. By depositing a material such as NiCr in a thickness of about 200 to 500 mm on the front and back surfaces of a wafer having a pyroelectric effect, an electrode, a conductor It describes that a pattern is formed and cut by a method such as dicing to obtain individual pyroelectric elements.

JP 2003-133603 A Japanese Patent No. 3773623

  In the infrared detector using the pyroelectric element composed of the dual element or the quad element described above, the cost of the pyroelectric substrate of the pyroelectric element is high, and further cost reduction is desired. Further, in the infrared detector using the pyroelectric element composed of the above-described dual element or quad element, further improvement in sensitivity is desired.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide an infrared detector capable of reducing cost and achieving high sensitivity, and a method for manufacturing the same. is there.

  An infrared detector according to the present invention includes an infrared detection element having a plurality of pyroelectric elements mounted on a substrate, a signal processing unit that processes an output signal of the infrared detection element, and the infrared detection element and the signal processing unit. Each of the pyroelectric elements includes one light receiving portion, and a first output terminal portion and a second output terminal portion electrically connected to the light receiving portion. The light receiving unit includes first and second electrodes that are formed on the front side and the back side of the pyroelectric substrate and face each other, and a portion of the pyroelectric substrate that is sandwiched between the first electrode and the second electrode. In each of the light receiving portions, the thickness of the first electrode is made thinner than the thickness of the second electrode.

  In this infrared detector, each of the pyroelectric elements is disposed so that the first output terminal portion and the second output terminal portion do not overlap in the thickness direction of the pyroelectric substrate. preferable.

  In this infrared detector, the first output terminal part, the second output terminal part of each pyroelectric element, and the wiring part of the substrate are electrically connected by a joint made of a conductive adhesive. It is preferable to become.

  In this infrared detector, it is preferable that the substrate is provided with a hole for thermal insulation in each of the projection regions of the light receiving portions.

  In the method of manufacturing the infrared detector of the present invention, in the formation of the pyroelectric element, after preparing a wafer made of a pyroelectric body capable of forming the necessary number of pyroelectric elements for a plurality of infrared detecting elements, Forming each second electrode on the back side of the wafer, forming each first electrode on the front side of the wafer, and separating the individual pyroelectric elements from the wafer. It is characterized by.

  The infrared detector of the present invention can reduce the cost and increase the sensitivity.

  The manufacturing method of the infrared detector of the present invention can provide an infrared detector capable of reducing the cost and increasing the sensitivity.

(A) is a schematic exploded perspective view of the infrared detector of Embodiment 1, (b) is a schematic perspective view of the infrared detection element in the infrared detector of Embodiment 1. 2 is a schematic cross-sectional view of an infrared detection element in the infrared detector according to Embodiment 1. FIG. It is explanatory drawing of the manufacturing method of the infrared detection element in the infrared detector of Embodiment 1. 6 is a schematic exploded perspective view of an infrared detector according to Embodiment 2. FIG. c

(Embodiment 1)
Below, the infrared detector 1 of this embodiment is demonstrated based on FIG. 1 and FIG.

  The infrared detector 1 includes an infrared detection element 10 having a plurality of pyroelectric elements 11 mounted on a substrate 18, a signal processing unit 20 that performs signal processing on an output signal of the infrared detection element 10, the infrared detection element 10, and signal processing. A package 30 in which the section 20 is housed. Each pyroelectric element 11 includes one light receiving portion 13, and a first output terminal portion 16 and a second output terminal portion 17 that are electrically connected to the light receiving portion 13. Each light receiving portion 13 is formed on the front side and the back side of the pyroelectric substrate 12 and is opposed to each other, and the first electrode 14 and the second electrode 15 on the pyroelectric substrate 12. It is comprised by the part 12a pinched | interposed. In each light receiving portion 13, the thickness of the first electrode 14 is made thinner than the thickness of the second electrode 15. The infrared detector 1 includes the infrared detecting element 10 in which a plurality of pyroelectric elements 11 each having only one light receiving unit 13 are mounted on the substrate 18, thereby reducing costs. In addition, high sensitivity can be achieved.

  Below, each component of the infrared detector 1 is demonstrated in detail.

  The signal processing unit 20 includes an IC element 22 that forms a signal processing circuit that processes an output signal (here, output current) of the infrared detection element 10, and a capacitor (not shown) that is externally attached to the IC element 22. And an MID (Molded Interconnect Devices) substrate 120 on which an IC element 22 and a capacitor are mounted. The MID substrate 120 has a circuit pattern 122 formed on the surface of a resin molded product 121. In the infrared detector 1, the infrared detection element 10 is mounted on the MID substrate 120, and a three-dimensional circuit block 130 including the infrared detection element 10 and the signal processing unit 20 is accommodated in the package 30. As a circuit configuration of the signal processing circuit in the IC element 22, for example, a circuit configuration of an integrated circuit (see paragraphs [0047] to [0048] etc.) disclosed in Japanese Patent No. 3367876 can be employed.

  The three-dimensional circuit block 130 is preferably provided with an appropriate shield plate (not shown) or a shield layer (not shown).

  The circuit of the signal processing unit 20 is not limited to the circuit configuration described above, and may include, for example, a current-voltage conversion circuit, a voltage amplification circuit (bandpass amplifier), a detection circuit, and an output circuit. The current-voltage conversion circuit converts an output current (pyroelectric current) that is an output signal output from the infrared detection element 10 into a voltage signal. The voltage amplification circuit amplifies a voltage in a predetermined frequency band in the voltage signal converted by the current-voltage conversion circuit. When the infrared ray to be detected by the infrared detector 1 is an infrared ray radiated from a human body, and the infrared detector 1 is used as a human body detection sensor, the voltage amplification circuit has a frequency component (for example, a frequency component close to human movement) ( It is preferable to amplify a voltage signal of a component centered at 1 Hz. The human body detection sensor detects a movement of an object (here, a human body) that emits infrared rays and outputs a detection signal. The detection circuit compares the voltage signal amplified by the voltage amplification circuit with a threshold value set as appropriate, and outputs a detection signal when the voltage signal exceeds the threshold value. The detection circuit can be configured by a comparison circuit using a comparator or the like. The output circuit outputs the detection signal of the detection circuit as a predetermined human body detection signal.

  For example, when the infrared detector 1 is used as a human body detection sensor, the infrared detector 1 is combined with a control circuit for turning on and off a switch element (a switching element, a relay, etc.) provided between the illumination load and the power source based on the output of the human body detection sensor. Can also be used. In the switch device including the infrared detector 1, the switch element, and the control circuit, when there is a temperature change in the surrounding environment of the infrared detection element 10, the human body does not exist in the detection area of the human body detection sensor. It is possible to prevent a malfunction that causes the lighting load to light up, and energy saving can be achieved.

  The use of the infrared detector 1 is not limited to the human body detection sensor, and can be used as, for example, a gas sensor or a flame sensor by appropriately changing the circuit configuration of the signal processing unit 20. In a gas sensor or a flame sensor using the infrared detector 1, when there is a temperature fluctuation in the surrounding environment of the infrared detection element 10, a notification is issued even though there is no gas or flame to be detected in the detection area. It is possible to prevent the occurrence of malfunction, which can increase the reliability.

  The package 30 is a can package. The package 30 includes a disk-shaped stem 131, a bottomed cylindrical cap 132 joined to the stem 131, and an infrared transmitting element disposed so as to close an opening 132 a formed at the bottom of the cap 132. It is comprised with the member 133. FIG.

  Both the stem 131 and the cap 132 are made of metal. The stem 131 has a circular shape in plan view, but is not limited thereto, and may be a polygonal shape, for example. Further, the shape of the cap 132 may be appropriately changed according to the shape of the stem 131. For example, when the planar shape of the stem 131 is rectangular, the planar shape of the cap 132 may be circular or rectangular.

  The stem 131 holds three lead pins 140 (only two are shown in FIG. 1) that are electrically connected to the signal processing unit 20. Each lead pin 140 is coupled to the MID substrate 120 and electrically connected to the signal processing unit. Of the three lead pins 140, one is for supplying power to the IC element 2, the other one is for signal output, and the other one is for ground. The power supply lead pin 140 and the signal output lead pin 140 are electrically insulated from the stem 131 by a sealing portion made of an insulating material (glass). The ground lead pin 140 is preferably electrically connected to the stem 131 by a sealing portion made of a conductive material and set to the same potential as the above-described shield plate or shield layer (for example, ground potential).

  The infrared transmitting member 133 has a function of transmitting infrared rays. The infrared transmitting member 133 is constituted by a flat optical filter. This optical filter is provided with a filter portion made of an optical multilayer film or the like on both sides or one side of a silicon substrate.

  For example, the optical multilayer film may have a configuration in which first thin films (for example, germanium thin films) and second thin films (for example, zinc sulfide thin films) having different refractive indexes are alternately stacked. When the infrared detector 1 is a human body detection sensor, the wavelength of the infrared ray to be detected is about 8 to 12 μm, and the center wavelength is about 10 μm. Therefore, the filter unit is, for example, a predetermined wavelength shorter than 8 μm (for example, The optical film thickness and the number of laminated layers of the first thin film and the second thin film may be designed so as to cut electromagnetic waves having a wavelength of 5 μm or less.

  The base material of the infrared transmitting member 133 is not limited to a silicon substrate, but may be, for example, a germanium substrate or a zinc sulfide substrate. However, using a silicon substrate is advantageous in terms of cost reduction. The filter section may be a multilayer optical film in which two types of thin films having different refractive indexes and the same optical film thickness are alternately stacked, and the material of each thin film is not particularly limited. In the case where germanium is used as the high refractive index material having a relatively high refractive index, for example, the above-described zinc sulfide can be adopted as the low refractive index material having a relatively low refractive index. For example, alumina, silicon dioxide, or the like can be used.

  A lens may be employed as the infrared transmitting member 133. When the infrared detector 1 is used as a human body detection sensor, it is more preferable that the infrared transmitting member 133 is a lens. The lens is preferably composed of a semiconductor lens (for example, a silicon lens).

  In manufacturing the semiconductor lens, for example, a semiconductor substrate (for example, a silicon substrate) is prepared. After that, an anode whose contact pattern with the semiconductor substrate is designed according to the desired lens shape is formed on one surface side of the semiconductor substrate so that the contact with the semiconductor substrate becomes ohmic contact. Thereafter, a porous portion serving as a removal site is formed by anodizing the other surface side of the semiconductor substrate in an electrolytic solution composed of a solution for removing oxides of constituent elements of the semiconductor substrate by etching. Thereafter, a semiconductor lens is formed by removing the porous portion. As a method for manufacturing a semiconductor lens to which this type of anodization technology is applied, for example, a method for manufacturing a semiconductor lens disclosed in Japanese Patent No. 3897055 and Japanese Patent No. 3897056 can be applied. In addition, what is necessary is just to isolate | separate the lens which consists of the above-mentioned semiconductor lens into each lens by dicing etc., after forming many lenses, using a semiconductor wafer (for example, silicon wafer) as a semiconductor substrate, for example.

  In the infrared detector 1, by adopting an aspheric lens made of a semiconductor lens as a lens, even in a lens having a short focal length and a large aperture diameter, aberration can be made smaller than that of a spherical lens formed by cutting. The package 30 can be thinned by reducing the focal length.

  The lens is preferably a semiconductor lens in which a lens part and a flange part surrounding the lens part are formed continuously and integrally. The infrared detector can be provided with a flange portion having a substantially constant thickness and each of both surfaces in the thickness direction being flat, thereby improving the accuracy of the distance between the lens and the infrared detection element 10 in the optical axis direction of the lens. It becomes.

  The infrared transmitting member 133 has a joint portion (not shown) made of a conductive joining material such as solder on the periphery of the opening 132 a on the rear surface side of the bottom of the cap 132. Are joined through. As a result, the package 30 can make the infrared transmitting member 133, the cap 132, and the stem 131 have the same potential.

  The infrared detector 1 preferably includes a polyethylene cover (not shown) that covers the package 30. The shape of the cover can be, for example, a dome shape. The cover is formed in a lens-like shape in which the infrared ray incident from the side opposite to the infrared transmitting member 133 side of the package 30 can be condensed to the infrared detecting element 10 from the opposite side. Preferably it is. This lens shape may be an array lens in which a plurality of lens portions are combined and the focal positions of the lens portions are the same, or may be a single lens.

  The cover can be configured to be positioned with respect to the package 30 such that the rear end edge of the cover is located rearward of the rear surface of the stem 131. As a result, when the infrared detector 1 is mounted on a circuit board such as a printed wiring board, a gap is formed between the stem 131 and the circuit board. That is, in the infrared detector 1, since the space surrounded by the cover, the package 30, and the circuit board constitutes a gas layer composed of an air layer, it is possible to suppress heat conduction from the circuit board to the stem 131. It is possible to suppress the occurrence of erroneous detection due to the fluctuation of the heat around the infrared detector 1.

  The infrared detection element 10 includes a plurality (four in this case) of pyroelectric elements 11 and a substrate 18 on which the plurality of pyroelectric elements 11 are mounted. The planar view shape of the substrate 18 is preferably rectangular, for example. The infrared detection element 10 is preferably provided with a plurality of pyroelectric elements 11 so as to be line-symmetric with respect to a center line along a direction orthogonal to the longitudinal direction of the substrate 18. In addition, the planar view shape of the board | substrate 18 is not restricted to a rectangular shape, For example, square shape may be sufficient.

  The board | substrate 18 is equipped with the base material 18a and the wiring part 18b formed in the one surface side of the base material 18a, and the pyroelectric element 11 is electrically connected. The base material 18a is preferably a substrate that is cheaper than a pyroelectric substrate and has a lower thermal conductivity than a metal. For example, a resin substrate, a silicon substrate in which an insulating film is formed on both sides in the thickness direction. A ceramic substrate (for example, an alumina substrate) or the like can be employed. Thereby, the infrared detecting element 10 does not provide the pyroelectric substrate 12 with U-shaped slits along the three sides of the square light-receiving part 13 in plan view, and the thermal insulation between the light-receiving parts 13. Can be improved. Here, in the infrared detection element 10, it is preferable that a thermal insulation hole 18 c is provided in each of the projection regions of the light receiving portions 13 on the substrate 18. As a result, the infrared detector 1 can improve the thermal insulation between the light receiving units 13 and can improve the thermal insulation between the light receiving unit 13 and the substrate 18. The hole 18c preferably has an opening size larger than the projection area of the light receiving unit 13. In the example of the infrared detecting element 10 shown in FIG. 2, the hole 18c is a through hole. The hole 18c is not limited to a through hole, and may be a depression. 1 and 2, only a part of the wiring portion 18b is shown.

  In the infrared detecting element 10, four pyroelectric elements 11 are mounted on one substrate 18. Here, the four pyroelectric elements 11 are arranged in a 2 × 2 array. Therefore, the infrared detecting element 10 has four light receiving portions 13 arranged in a 2 × 2 array. The infrared detection element 10 is arranged so that the center of one light receiving unit 13 is positioned at each of the four corners of the virtual square inside the outer peripheral line of the substrate 18 at the center of the substrate 18.

  In addition, the infrared detecting element 10 includes two light receiving units 13 that are diagonally connected in parallel among the four light receiving units 13, and two light receiving units 13 that are positioned at different diagonals are connected in reverse parallel. As described above, the wiring portion 18b of the substrate 18 is designed in a pattern. In short, in the infrared detection element 10, the direction along the longitudinal direction of the substrate 18 is in the X direction in one plane parallel to the substrate 18, and the direction along the short direction of the substrate 18 in the one plane is the Y direction. Then, the two light receiving parts 13 arranged along the X direction are connected in antiparallel, and the two light receiving parts 13 arranged along the Y direction are connected in antiparallel. In addition, the infrared detection element 10 has a wiring design 18b designed so that an output signal can be taken out from the two external connection terminals 18d.

  In the infrared detection element 10, the charges generated in the two light receiving units 13 are canceled by the temperature change of the surrounding environment between the two light receiving units 13 connected in antiparallel. The infrared detection element 10 is equivalent to a quad-type pyroelectric element in which four light receiving portions are formed on one pyroelectric substrate in terms of an equivalent circuit. Therefore, in the infrared detection element 10, when a temperature change occurs in the entire four light receiving parts 13, the charges generated in each light receiving part 13 are not output as signals.

  The pyroelectric element 11 is preferably a chip having a rectangular planar shape. The pyroelectric element 11 includes a square light receiving portion 13 at the center in the longitudinal direction. The chip size of the pyroelectric element 11 is 0.6 mm × 0.8 mm. That is, the pyroelectric element 11 has a short side length of 0.6 mm and a long side length of 0.8 mm. The chip size of the pyroelectric element 11 is not particularly limited.

  The pyroelectric element 11 includes a first output terminal portion 16 at one end in the longitudinal direction and a second output terminal portion 17 at the other end in the longitudinal direction. In short, in the pyroelectric element 11, the pyroelectric substrate 12 has a rectangular plate shape, and one light receiving portion 13 is formed in the central portion of the pyroelectric substrate 12 in the longitudinal direction. A first output terminal portion 16 and a second output terminal portion 17 are formed at one end and the other end, respectively.

  The first output terminal unit 16 is electrically connected to the first electrode 14 of the light receiving unit 13 on the front side of the pyroelectric substrate 12. The second output terminal unit 17 is electrically connected to the second electrode 15 of the light receiving unit 13 on the back side of the pyroelectric substrate 12.

The pyroelectric substrate 12 is composed of a single crystal LiTaO ₃ substrate. The material of the pyroelectric substrate 12 is LiTaO ₃ , but is not limited to this. For example, LiNbO ₃ , PbTiO ₃ , PZT, PZT-PMN (: Pb (Zr, Ti) O ₃ —Pb ( Mn, Nb) O ₃ ) or the like may be employed.

  The direction of spontaneous polarization of the pyroelectric substrate 12 is one direction along the thickness direction of the pyroelectric substrate 12, and is the upward direction of FIG.

  The thickness of the pyroelectric substrate 12 is set to 50 μm, but is not limited to this value. The thickness of the pyroelectric substrate 12 is preferably thinner, for example, from the viewpoint of improving the sensitivity of the infrared detection element 10. For this reason, it is preferable to set the thickness of the pyroelectric substrate 12 in a range of about 30 μm to 150 μm. If the thickness of the pyroelectric substrate 12 is less than 30 μm, there is a concern of breakage due to fragility, and if it is more than 150 μm, the sensitivity may be lowered.

  Regarding the surface roughness of the surface of the pyroelectric substrate 12, the arithmetic average roughness Ra specified in JIS B 0601-2001 (ISO 4287-1997) is set to 170 μm, but the value is limited to this value. is not. The arithmetic average roughness Ra is preferably 130 nm or more, and more preferably 150 nm or more. This is because, if the flatness of the surface of the pyroelectric substrate 12 is too high and the arithmetic average roughness Ra is too small, the infrared rays incident on the light receiving unit 13 and the surface of the pyroelectric substrate 12 are likely to be reflected, and the infrared absorption. This is because the efficiency is lowered and the sensitivity is lowered.

  The 1st electrode 14 and the 2nd electrode 15 are comprised by the electrically conductive film which has electroconductivity and can absorb the infrared rays of a detection target. This conductive film is made of a Ni film. The conductive film is not limited to the Ni film but may be, for example, a NiCr film or a gold black film. The thicker the conductive film, the smaller the electric resistance. On the other hand, the thinner the conductive film, the higher the infrared absorption. Here, in the pyroelectric element 11, the thickness of the first electrode 14 is smaller than the thickness of the second electrode 15. Thereby, the infrared detector 1 can increase the sensitivity.

  The thickness of the first electrode 14 is set to 30 nm, but is not limited to this value. It has been confirmed by experiments that the sensitivity of the infrared detection element 10 is reduced if the thickness of the first electrode 14 is too thick. It is assumed that this is because if the thickness of the first electrode 14 is too thick, the flatness of the first electrode 14 is increased and the amount of infrared absorption at the first electrode 14 is reduced. For this reason, the thickness of the first electrode 14 is preferably 40 nm or less, and more preferably 21 nm or less. The first electrode 14 can be formed by, for example, vapor deposition or sputtering.

  The thickness of the second electrode 15 is set to 100 nm, but is not limited to this value. The inventors of the present application have confirmed through experiments that the sensitivity of the infrared detection element 10 decreases if the thickness of the second electrode 15 is too thin. This is because if the thickness of the second electrode 15 is too thin, the amount of infrared absorption at the second electrode 15 is reduced with respect to the infrared light transmitted through the first electrode 14 and the pyroelectric substrate 12. Inferred. For this reason, the thickness of the second electrode 15 is preferably 80 nm or more, and more preferably 110 nm or more. The second electrode 15 can be formed by, for example, vapor deposition or sputtering.

  The first output terminal portion 16 is preferably made of the same material and thickness as the first electrode 14. Thereby, in forming the pyroelectric element 11, the first electrode 14 and the first output terminal portion 16 can be formed at the same time, and the first electrode 14 and the first output terminal portion 16 are formed as a continuous film. Is possible.

  The second output terminal portion 17 preferably has the same material and thickness as the second electrode 15. Thereby, in forming the pyroelectric element 11, the second electrode 15 and the second output terminal portion 17 can be formed simultaneously, and the second electrode 14 and the second output terminal portion 17 are formed as a continuous film. Is possible.

  The first output terminal portion 16 and the second output terminal portion 17 of the pyroelectric element 11 are electrically and mechanically connected to the wiring portion 18 of the substrate 18 through a joint portion 19 made of a conductive adhesive. As the conductive adhesive, it is preferable to employ an organic resin-based conductive adhesive. Thereby, the infrared detection element 10 can suppress heat conduction from the substrate 18 to the pyroelectric element 11. In addition, the infrared detecting element 10 may be appropriately provided with an adhesive portion made of an electrically insulating adhesive in order to reinforce the mechanical connection between the pyroelectric element 11 and the substrate 18 separately from the joint portion 19. .

  The two external connection terminals 18d of the substrate 18 and the signal processing unit 20 can be electrically connected by, for example, solder, a conductive adhesive, a conductive paste, a thin metal wire (wire), or the like. The conductive adhesive is, for example, an epoxy resin or polyimide resin adhesive containing Ag or Au powder. Examples of the conductive paste include silver paste, gold paste, and copper paste. The substrate 18 is provided with two external connection terminals 18d on the one surface side of the base material 18a. However, two through wirings are provided at appropriate locations on the base material 18a, and the other surface side of the base material 18a is provided. Two external connection terminals 18d may be provided.

  Each pyroelectric element 11 is preferably arranged such that the first output terminal portion 16 and the second output terminal portion 17 do not overlap in the thickness direction of the pyroelectric substrate 12. Thereby, the infrared detector 1 can prevent the occurrence of parasitic capacitance between the first output terminal portion 16 and the second output terminal portion 17 in each of the pyroelectric elements 11, and the first It is possible to prevent the first output terminal portion 16 and the second output terminal portion 17 from being short-circuited.

  Below, the manufacturing method of the infrared detector 1 is demonstrated based on FIG.

  In forming the pyroelectric elements 11, a wafer 100 made of a pyroelectric material capable of forming the necessary number of pyroelectric elements 11 for the plurality of infrared detecting elements 10 is prepared (FIG. 3A).

  After the wafer 100 is prepared, a process of forming each second electrode 15 on the back side of the wafer 100 (hereinafter referred to as a first process) and a process of forming each first electrode 14 on the front side of the wafer 100 (hereinafter referred to as “first process”). (Referred to as the second step). In the present embodiment, in the first process, a predetermined number of second electrodes 15 and a predetermined number of second output terminal portions 17 arranged in a prescribed direction of the wafer 100 (for example, a direction parallel or orthogonal to an orientation flat (not shown)). A conductive film is formed. In the present embodiment, in the second step, a predetermined number of first electrodes 14 and a predetermined number of first output terminal portions 16 arranged in a prescribed direction of the wafer 100 (for example, a direction parallel or orthogonal to an orientation flat (not shown)). A conductive film 114 is formed (FIG. 3B).

  After the second step, a step (hereinafter referred to as a third step) for dividing the wafer 100 into individual pyroelectric elements 11 (hereinafter referred to as a third step) is performed (FIG. 3C). The third step is a dicing step, in which the wafer 100 is cut by rotating the dicing blade at an appropriate rotation speed (for example, 40000 rpm). A one-dot chain line in FIG. 3C schematically shows a line along which the dicing blade moves. The dicing process is not limited to a method using a dicing blade, and may be laser dicing using a laser. In laser dicing, it is possible to increase the energy density by condensing the laser light from the laser, locally heat the wafer 100, and melt or evaporate the heated portion for cutting. In laser dicing, stealth dicing (registered trademark) technology can also be used.

  After the third step, the pyroelectric elements 11 on the adhesive resin tape 110 are picked up one by one with a pickup tool (not shown) (FIG. 3D), and a plurality of pyroelectric elements 11 are mounted on the substrate 18. Thus, the infrared detecting element 10 is formed (FIG. 3E), for example, an ultraviolet curable dicing tape can be used as the adhesive resin tape 110. Thereby, the wafer 100 has a strong adhesive force during dicing. While holding the chip and dicing, it is possible to reduce the adhesive force by irradiating with ultraviolet rays and improve the pick-up property, and the adhesive resin tape 110 is not limited to the ultraviolet curable dicing tape, For example, a thermosetting dicing tape may be used.

  In the manufacturing method of the infrared detector 1, after the infrared detection element 10 is mounted on the MID substrate 120 of the signal processing unit 20, each lead pin 140 is fixed to the circuit block 130 including the infrared detection element 10 and the signal processing unit 20 in advance. Then, the cap 132 and the stem 131 to which the infrared transmitting member 133 is fixed in advance may be fixed.

  In the manufacturing method of the infrared detector 1 described above, when forming the pyroelectric elements 11, a wafer 100 made of a pyroelectric material capable of forming the necessary number of pyroelectric elements 11 for the plurality of infrared detecting elements 10 was prepared. Thereafter, a step of forming each second electrode 14 on the back side of the wafer 100, a step of forming each first electrode 15 on the front side of the wafer 100, and a step of dividing the wafer 100 into individual pyroelectric elements 11 It has. Thereby, the manufacturing method of the infrared detector 1 can provide the infrared detector 1 capable of reducing the cost and increasing the sensitivity.

(Embodiment 2)
Below, the infrared detector 1 of this embodiment is demonstrated based on FIG.

  The infrared detector 1 of the present embodiment has substantially the same basic configuration as the infrared detector 1 of the first embodiment, and only the components of the signal processing unit 20 are different. The same reference numerals are given and description thereof is omitted as appropriate.

  The signal processing unit 20 in the infrared detector 1 of this embodiment includes a field effect transistor 202 for impedance conversion in which the infrared detection element 10 is connected to a gate, and a high resistance value for setting the gate potential of the field effect transistor 202. This is a current-voltage conversion circuit using the resistor 203. That is, the signal processing unit 20 includes a field effect transistor 202, a resistor 203, and a circuit board 201 made of a printed wiring board on which these are mounted. The circuit board 201 is formed in a disk shape.

  The infrared detection element 10 is supported by two support bases 204, 204 arranged on one surface of the circuit board 201.

  The package 30 has substantially the same configuration as that of the first embodiment, and includes a metal stem 131, a metal cap 132, and an infrared transmission member 133. The stem 131 holds three lead pins 140 for taking out the output of the signal processing unit 20 to the outside. Each lead pin 140 is coupled to the circuit board 201 and is electrically connected to the signal processing unit 20.

  Also in the infrared detector 1 of the present embodiment described above, by using the infrared detection element 10 described in the first embodiment, the cost can be reduced and the sensitivity can be increased. Become.

  In the above-described first and second embodiments, the infrared detection element 10 has been described as having the same equivalent circuit as the quad-type pyroelectric element, but is not limited thereto. For example, the infrared detection element 10 may have a configuration in which the two light receiving units 13 are connected in reverse parallel by mounting the two pyroelectric elements 11 on the substrate 18. The infrared detecting element 10 having this configuration has an equivalent circuit similar to that of a dual type pyroelectric element. In addition, when the infrared detecting element 10 includes four pyroelectric elements 11, the infrared detecting element 10 is not limited to a structure arranged in a 2 × 2 array, and may have a structure arranged in a 1 × 4 array, for example. .

  In the first and second embodiments, the can package is exemplified as the package 30, but the package 30 is not limited to the can package. The package 30 may be, for example, a surface mount type ceramic package.

DESCRIPTION OF SYMBOLS 1 Infrared detector 10 Infrared detection element 11 Pyroelectric element 12 Pyroelectric substrate 12a The part pinched | interposed into the 1st electrode and the 2nd electrode in the pyroelectric substrate 13 Light-receiving part 14 1st electrode 15 2nd electrode 16 1st Output terminal portion 17 Second output terminal portion 18 Substrate 18b Wiring portion 18c Hole 19 Joint portion 20 Signal processing portion 30 Package 100 Wafer

Claims (5)

  An infrared detection element having a plurality of pyroelectric elements mounted on a substrate; a signal processing unit that processes an output signal of the infrared detection element; and a package that houses the infrared detection element and the signal processing unit. Each of the pyroelectric elements includes one light receiving portion, and a first output terminal portion and a second output terminal portion electrically connected to the light receiving portion, and each of the light receiving portions includes a pyroelectric substrate. Each of the light receiving parts, each of which is formed by a first electrode and a second electrode which are formed on the front side and the back side of the Pt and face each other, and a portion sandwiched between the first electrode and the second electrode in the pyroelectric substrate. The infrared detector is characterized in that the thickness of the first electrode is made thinner than the thickness of the second electrode.   2. Each of the pyroelectric elements is arranged such that the first output terminal portion and the second output terminal portion do not overlap in the thickness direction of the pyroelectric substrate. The described infrared detector.   The first output terminal portion, the second output terminal portion of each pyroelectric element, and the wiring portion of the substrate are electrically connected by a joint portion made of a conductive adhesive. The infrared detector according to claim 1 or 2.   The infrared detector according to claim 1, wherein the substrate is provided with a hole for thermal insulation in each of the projection regions of the light receiving units.   5. The method of manufacturing an infrared detector according to claim 1, wherein the pyroelectric elements can be formed in a number necessary for a plurality of infrared detecting elements. After preparing a wafer made of pyroelectric material, forming each second electrode on the back side of the wafer; forming each first electrode on the front side of the wafer; and And a step of separating the electric element into individual pieces.

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