Patent Description:
Patent Document <NUM> discloses an optical element in which a Fabry-Perot interference filter and a light detector (a light receiving part) which receives light that has passed through the Fabry-Perot interference filter are integrally formed. A conductive fixed reflective film which faces a movable reflective film is provided in the optical element. Thus, generation of noise components (crosstalk noise) in a detection signal of the light detector when a driving voltage is applied to the Fabry-Perot interference filter is curbed.

Patent document <NUM> discloses an optical instrument including a tunable free-space filter as a wavelength selector. The instrument may further comprise passive interferometric structures within the optical instrument that create a stable wavelength reference. The optical instrument further comprises a detector having an output and a signal processor connected to receive a signal from the detector output, the signal processor converting the signal received from the detector output to power v. wavelength data.

However, in a structure in which the Fabry-Perot interference filter and the light detector are integrally formed as in the above-described optical element, since the Fabry-Perot interference filter and the light detector are in proximity to each other, it is difficult to sufficiently curb the crosstalk noise. On the other hand, it is conceivable to separate a mounting substrate on which the light detector is mounted from the Fabry-Perot interference filter using a support member such as a spacer. However, according to findings of the inventor, even when such a configuration is adopted, crosstalk noise may be mixed into the detection signal of the light detector due to a current component flowing from the Fabry-Perot interference filter to the light detector via the support member and the mounting substrate.

One aspect of the disclosure is to provide a light detection device capable of effectively curbing crosstalk noise in a detection signal of a light detector.

A light detection device according to one aspect of the disclosure includes a mounting substrate having a main surface, a light detector disposed on the main surface of the mounting substrate, a Fabry-Perot interference filter configured so that a distance between a pair of mirror parts changes due to an electrostatic force by forming a gap between the pair of mirror parts facing each other, a support member provided on the main surface of the mounting substrate and configured to support the Fabry-Perot interference filter so that the Fabry-Perot interference filter and the light detector are separated from each other, and a ground part connectable to a ground potential, wherein a second current path having a smaller electrical resistance than that of an arbitrary first current path extending from the Fabry-Perot interference filter to the light detector via the support member and the mounting substrate is formed between the Fabry-Perot interference filter and the ground part, and the second current path is configured to release a current component, which flows from the Fabry-Perot interference filter to the support member, to the ground part.

In the light detection device, the Fabry-Perot interference filter and the light detector are separated by the support member. Thus, the distance between the Fabry-Perot interference filter and the light detector can be increased. As a result, crosstalk noise in a detection signal of the light detector due to a driving voltage applied to the Fabry-Perot interference filter is curbed. Further, in the light detection device, the second current path having a lower electrical resistance than that of an arbitrary first current path from the Fabry-Perot interference filter to the light detector via the support member and the mounting substrate is formed between the Fabry-Perot interference filter and the ground part (the ground potential). Therefore, the current component which flows from the Fabry-Perot interference filter to the support member is more likely to flow to the ground part than to the light detector. Thus, the crosstalk noise caused by the current component flowing from the Fabry-Perot interference filter to the light detector via the support member and the mounting substrate is curbed. As described above, according to the above-described light detector, the crosstalk noise in the detection signal of the light detector can be effectively curbed.

The light detection device may further include a conductive connecting member configured to electrically connect the support member or the mounting substrate to the ground part so that a current component flowing from the Fabry-Perot interference filter to the support member is released to the ground part. According to such a configuration, the current component which flows from the Fabry-Perot interference filter to the support member can be appropriately released to the ground part via the conductive connecting member.

The connecting member may electrically connect a region along the main surface of the mounting substrate to the ground part, and the second current path may be a path extending from the Fabry-Perot interference filter to the ground part via the support member, the region along the main surface, and the connecting member. According to such a configuration, the current component which will flow to the light detector via the mounting substrate can be appropriately released to the ground part via the connecting member.

The mounting substrate may include an insulating layer having a first surface as the main surface and a second surface on a side opposite to the first surface, and a metal layer provided on the second surface side of the insulating layer, and the region along the main surface may be the metal layer. According to such a configuration, while the insulation between the light detector and the metal layer is ensured by the insulating layer, the current component which will flow to the light detector can be appropriately released to the ground part via the metal layer.

An opening part which exposes a surface of the metal layer on an insulating layer side may be formed in the insulating layer, and the connecting member may be connected to the metal layer via the opening part and connected to the ground part. According to such a configuration, for example, the metal layer and the ground part can be appropriately and easily connected by wire bonding.

The metal layer may be provided at least at an edge portion of the mounting substrate when seen in a thickness direction of the mounting substrate, a portion of the metal layer provided at the edge portion of the mounting substrate may be exposed to the outside, and the connecting member may be a conductive resin material which is provided to cover the edge portion of the mounting substrate and connects the portion of the metal layer to the ground part. According to such a configuration, the metal layer and the ground part can be appropriately and easily connected by providing the conductive resin material to cover the edge portion of the mounting substrate.

The metal layer may be provided to overlap a region on the mounting substrate in which the support member is provided when seen in the thickness direction of the mounting substrate. According to such a configuration, the current component which flows from the Fabry-Perot interference filter to the mounting substrate via the support member can be appropriately released to the ground part via the metal layer provided in a region directly below the support member.

The metal layer may be provided not to overlap the light detector when seen in the thickness direction of the mounting substrate. According to such a configuration, the metal layer and the light detector do not have portions which face each other in the thickness direction of the mounting substrate. Thus, an influence of parasitic capacitance on the light detector can be curbed. As a result, it is possible to curb a decrease in a response speed of the detection signal of the light detector due to such parasitic capacitance.

The metal layer may be provided to overlap an arbitrary current path between the region on the mounting substrate in which the support member is provided and the light detector when seen in the thickness direction of the mounting substrate. According to such a configuration, the metal layer is formed to divide an arbitrary current path between the region on the mounting substrate in which the support member is provided and the light detector when seen in the thickness direction of the mounting substrate. Thus, the current component which will flow from the region in which the support member is provided to the light detector can be appropriately captured by the metal layer and can be released to the ground part.

The mounting substrate may have an insulating layer having a first surface as the main surface, and a metal layer provided between the first surface of the insulating layer and the support member, and the region along the main surface may be the metal layer. According to such a configuration, the current component which flows from the Fabry-Perot interference filter to the mounting substrate via the support member can be appropriately released to the ground part from the metal layer provided in the region directly below the support member.

The ground part may be a stem to which a surface of the mounting substrate on a side opposite to the main surface is fixed, the mounting substrate may include a first layer having a first surface as the main surface and a second surface on a side opposite to the first surface, and a second layer provided on the second surface side of the first layer, the connecting member may be disposed between a surface of the second layer on a side opposite to the first layer and the stem and electrically connect the surface of the second layer on the side opposite to the first layer to the stem, an electrical resistance of a current path extending from the support member to the stem via the first layer and the second layer may be smaller than that of a current path extending from the support member to the light detector via at least one of the first layer and the second layer, and the second current path may be a path extending from the Fabry-Perot interference filter to the stem via the support member, the first layer, the second layer, and the connecting member. According to such a configuration, the current component which flows from the Fabry-Perot interference filter to the mounting substrate via the support member can be appropriately released to the stem (the ground part) by passing through the inside of the mounting substrate (the first layer and the second layer).

The connecting member may electrically connect the support member to the ground part, and the second current path may be a path extending from the Fabry-Perot interference filter to the ground part via the support member and the connection member. According to such a configuration, before the current component which flows from the Fabry-Perot interference filter to the support member reaches the mounting substrate, the current component can be appropriately released from the support member to the ground part.

The light detection device may further include a metal film disposed between the support member and the Fabry-Perot interference filter, the connecting member may electrically connect the support member to the ground part via the metal film, and the second current path may be a path extending from the Fabry-Perot interference filter to the ground part via the metal film and the connecting member. According to such a configuration, before the current component which flows from the Fabry-Perot interference filter to the support member reaches the support member, the current component can be appropriately released from the metal film to the ground part.

According to one aspect of the disclosure, it is possible to provide a light detection device capable of effectively curbing crosstalk noise in a detection signal of a light detector.

In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicate description thereof will be omitted.

<FIG> is a plan view of a spectroscopic sensor (a light detection device) 1A. <FIG> is a cross-sectional view taken along line II-II of <FIG>. <FIG> is an exploded perspective view of a part of the spectroscopic sensor 1A. In <FIG>, illustration of a cap <NUM>, a light transmitting member <NUM>, and a band pass filter <NUM> which will be described later is omitted. As shown in <FIG> and <FIG>, the spectroscopic sensor 1A includes a package <NUM>. The package <NUM> is a CAN package which accommodates a wiring substrate <NUM> (a mounting substrate), a light detector <NUM>, a temperature compensation element <NUM> such as a thermistor, a plurality of (two in this case) spacers <NUM> (support members), a band pass filter <NUM>, and a Fabry-Perot interference filter <NUM>. The package <NUM> has a stem <NUM> (a ground part) and a cap <NUM>. The cap <NUM> has a side wall <NUM> and a top wall <NUM> which are integrally formed. The stem <NUM> and the cap <NUM> are made of a metal material and are airtightly joined to each other. In the package <NUM>, the side wall <NUM> is formed in a cylindrical shape with a predetermined line L as a center line. The top wall <NUM> is formed in a disk shape with the line L as a center line. The stem <NUM> and the top wall <NUM> face each other in a direction D1 parallel to the line L and respectively close both ends of the side wall <NUM>. In the spectroscopic sensor 1A, the stem <NUM> is connected to a ground potential. The ground potential means an arbitrarily determined reference potential and is not limited to <NUM> V.

The wiring substrate <NUM> is fixed to an inner surface 21a of the stem <NUM>. The light detector <NUM> and the temperature compensation element <NUM> are mounted (disposed) on a main surface 3a of the wiring substrate <NUM>. The main surface 3a is a surface which faces the top wall <NUM> and the Fabry-Perot interference filter <NUM>. As shown in <FIG>, a wiring layer <NUM> on which the light detector <NUM> is mounted, a wiring layer <NUM> on which the temperature compensation element <NUM> is mounted, and electrode pads <NUM> and <NUM> for relay are provided on the main surface 3a of the wiring substrate <NUM>. The wiring layer <NUM> has a mounting part 31a in which the light detector <NUM> is disposed, an electrode pad 31b, and a wiring part 31c which electrically connects the mounting part 31a to the electrode pad 31b. The wiring layer <NUM> has a mounting part 32a in which the temperature compensation element <NUM> is disposed, an electrode pad 32b, and a wiring part 32c which electrically connects the mounting part 32a to the electrode pad 32b. In the embodiment, as an example, the wiring layer <NUM>, the wiring layer <NUM>, the electrode pad <NUM>, and the electrode pad <NUM> are formed of a laminated film made of Cr-Pt-Au. However, the wiring layer <NUM>, the wiring layer <NUM>, the electrode pad <NUM>, and the electrode pad <NUM> may be formed of a material other than the above-described material and may be formed of, for example, a single-layer film such as Al or Au, or a laminated film such as Ti-Pt-Au, Ti-Ni-Au, and Cr-Au.

The light detector <NUM> is disposed on a line L. More specifically, the light detector <NUM> is disposed so that a center line of a light receiving part 4a coincides with the line L. The light detector <NUM> is, for example, an infrared detector which is a quantum sensor using InGaAs or the like, or a thermal sensor using a thermopile or a bolometer. When light in each of wavelength ranges of ultraviolet (UV), visible, and near infrared rays is detected, for example, a silicon photodiode or the like can be used as the light detector <NUM>. The light detector <NUM> may have one light receiving part 4a, or may have a plurality of array-shaped light receiving parts 4a. Further, a plurality of light detectors <NUM> may be mounted on the wiring substrate <NUM>.

A plurality of spacers <NUM> are fixed on the main surface 3a of the wiring substrate <NUM>. The Fabry-Perot interference filter <NUM> is fixed on the plurality of spacers <NUM>. That is, the plurality of spacers <NUM> support the Fabry-Perot interference filter <NUM> on the main surface 3a of the wiring substrate <NUM>. A space is formed between the Fabry-Perot interference filter <NUM> and the main surface 3a of the wiring substrate <NUM> by such spacers <NUM>, and the Fabry-Perot interference filter <NUM> and the light detector <NUM> are separated from each other. For example, silicon, ceramic, quartz, glass, plastic or the like can be used as a material of each of the spacers <NUM>. The Fabry-Perot interference filter <NUM> is fixed on the plurality of spacers <NUM> by, for example, an adhesive. For example, a flexible resin material (for example, a resin material such as silicone-based, urethane-based, epoxy-based, acrylic-based, or hybrid materials) can be used as the adhesive for adhering the spacer <NUM> and the Fabry-Perot interference filter <NUM>. The Fabry-Perot interference filter <NUM> is disposed on the line L. More specifically, the Fabry-Perot interference filter <NUM> is disposed so that a center line of a light transmission region 10a thereof coincides with the line L. The spacers <NUM> may be integrally formed with the wiring substrate <NUM>. Further, the Fabry-Perot interference filter <NUM> may be supported by one spacer <NUM> instead of the plurality of spacers <NUM>.

A plurality of lead pins <NUM> and 8A are fixed to the stem <NUM>. More specifically, each of the lead pins <NUM> passes through the stem <NUM> in a state in which electrical insulation and airtightness with the stem <NUM> is maintained. The electrode pad 31b, the electrode pad 32b, the electrode pad <NUM>, the electrode pad <NUM>, and terminals (a first terminal <NUM>, and a second terminal <NUM>) of the Fabry-Perot interference filter <NUM> provided on the wiring substrate <NUM> are electrically connected to each of the lead pins <NUM> by a wire <NUM>. The electrode pad <NUM> and the terminal of the light detector <NUM> are electrically connected by the wire <NUM>. That is, the lead pin <NUM> and the light detector <NUM> are connected by two wires <NUM> via the electrode pad <NUM> for relay. In this case, even when a distance between the light detector <NUM> and the lead pin <NUM> is long, it is possible to prevent a short circuit at an unnecessary location and to improve a yield of the spectroscopic sensor 1A. However, the electrode pad <NUM> may be omitted, and the lead pin <NUM> and the light detector <NUM> may be connected by one wire <NUM> without interposing the electrode pad <NUM> therebetween. Similarly, the electrode pad <NUM> and the terminal of the temperature compensation element <NUM> are electrically connected by the wire <NUM>. That is, the lead pin <NUM> and the temperature compensation element <NUM> are connected by two wires <NUM> via the electrode pad <NUM> for relay. In this case, even when a distance between the temperature compensation element <NUM> and the lead pin <NUM> is long, it is possible to prevent a short circuit at an unnecessary location and to improve the yield of the spectroscopic sensor 1A. However, the electrode pad <NUM> may be omitted, and the lead pin <NUM> and the temperature compensation element <NUM> may be connected by one wire <NUM> without interposing the electrode pad <NUM> therebetween. With the above connection configuration, input and output of an electrical signal to/from each of the light detector <NUM>, the temperature compensation element <NUM>, and the Fabry-Perot interference filter <NUM> is performed. Further, in the embodiment, as an example, two lead pins 8A connected to the ground potential are connected to the stem <NUM> by the wire <NUM>. Thus, the stem <NUM> is connected to the ground potential.

An opening 2a is formed in the package <NUM>. The opening 2a is formed in the top wall <NUM> of the cap <NUM> so that a center line of the opening 2a coincides with the line L. When seen in the direction D1, a shape of the opening 2a is circular. A light transmitting member <NUM> is disposed on an inner surface 222a of the top wall <NUM> to close the opening 2a. The light transmitting member <NUM> is airtightly joined to the inner surface 222a of the top wall <NUM>. The light transmitting member <NUM> has a light incident surface 23a and a light emitting surface (an inner surface) 23b which face each other in the direction D1, and a side surface 23c. The light incident surface 23a of the light transmitting member <NUM> is substantially flush with an outer surface of the top wall <NUM> at the opening 2a. The side surface 23c of the light transmitting member <NUM> is in contact with an inner surface 221a of the side wall <NUM> of the package <NUM>. That is, the light transmitting member <NUM> reaches the inside of the opening 2a and the inner surface 221a of the side wall <NUM>. Such a light transmitting member <NUM> is formed, for example, by disposing glass pellets inside the cap <NUM> and melting the glass pellets in a state in which the opening 2a faces downward. That is, the light transmitting member <NUM> can be formed of fused glass.

The band pass filter <NUM> is fixed to the light emitting surface 23b of the light transmitting member <NUM> by an adhesive member or the like. The band pass filter <NUM> selectively transmits light in a measurement wavelength range of the spectroscopic sensor 1A (light in a predetermined wavelength range to be incident on the light transmission region 10a of the Fabry-Perot interference filter <NUM>) among the light transmitted through the light transmitting member <NUM> (that is, only light in the predetermined wavelength range is transmitted). The band pass filter <NUM> has a quadrangular plate shape. The band pass filter <NUM> is, for example, a dielectric multilayer film (for example, a multilayer film configured of a combination of a high-refractive material such as TiO<NUM> and Ta<NUM>O<NUM> and a low-refractive material such as SiO<NUM> and MgF<NUM>) formed on a surface of the light transmitting member formed of a light transmitting material (for example, silicon, glass, or the like) in a quadrangular plate shape.

In the spectroscopic sensor 1A configured as described above, when light is incident on the band pass filter <NUM> from the outside through the light transmitting member <NUM>, the light in a predetermined wavelength range is transmitted through the band pass filter <NUM>. When the light transmitted through the band pass filter <NUM> is incident on the light transmission region 10a of the Fabry-Perot interference filter <NUM>, light having a predetermined wavelength among the light in the predetermined wavelength range is selectively transmitted. The light transmitted through the light transmission region 10a of the Fabry-Perot interference filter <NUM> is incident on the light receiving part 4a of the light detector <NUM> and is detected by the light detector <NUM>. That is, the light detector <NUM> converts the light transmitted through the Fabry-Perot interference filter <NUM> into an electrical signal and outputs it. For example, the light detector <NUM> outputs an electrical signal (a detection signal) having a size corresponding to an intensity of the light incident on the light receiving part 4a.

As shown in <FIG> and <FIG>, in the Fabry-Perot interference filter <NUM>, the light transmission region 10a which transmits light according to a distance between a first mirror part <NUM> and a second mirror part <NUM> (between a pair of mirror parts) is provided on the line L. The light transmission region 10a is, for example, a cylindrical region. In the light transmission region 10a, the distance between the first mirror part <NUM> and the second mirror part <NUM> is controlled with extremely high accuracy. That is, the light transmission region 10a is a region in the Fabry-Perot interference filter <NUM> which can control the distance between the first mirror part <NUM> and the second mirror part <NUM> to a predetermined distance in order to selectively transmit light having a predetermined wavelength, and is a region through which light having a predetermined wavelength corresponding to the distance between the first mirror part <NUM> and the second mirror part <NUM> can be transmitted.

The Fabry-Perot interference filter <NUM> includes a rectangular plate-shaped substrate <NUM>. The substrate <NUM> has a first surface 41a and a second surface 41b which face each other in the direction D1 parallel to the line L. The first surface 41a is a surface on the light incident side. The second surface 41b is a surface on the light detector <NUM> side (that is, the light emitting side). A first layer structure <NUM> is disposed on the first surface 41a. A second layer structure <NUM> is disposed on the second surface 41b.

The first layer structure <NUM> is configured by laminating a first antireflection layer <NUM>, a first laminated body <NUM>, a first intermediate layer <NUM>, and a second laminated body <NUM> in this order on the first surface 41a. A void (an air gap) S is formed between the first laminated body <NUM> and the second laminated body <NUM> by the frame-shaped first intermediate layer <NUM>. The substrate <NUM> is made of, for example, silicon, quartz, glass, or the like. When the substrate <NUM> is made of silicon, the first antireflection layer <NUM> and the first intermediate layer <NUM> are made of, for example, a silicon oxide. A thickness of the first intermediate layer <NUM> is, for example, several tens of nm to several tens of µm.

A portion of the first laminated body <NUM> corresponding to the light transmission region 10a serves as the first mirror part <NUM>. The first laminated body <NUM> is formed by alternately laminating a plurality of polysilicon layers and a plurality of silicon nitride layers one by one. An optical thickness of each of the polysilicon layers and the silicon nitride layers constituting the first mirror part <NUM> is preferably an integral multiple of <NUM>/<NUM> of a central transmission wavelength. The first mirror part <NUM> may be disposed directly on the first surface 41a without interposing the first antireflection layer <NUM> therebetween.

A portion of the second laminated body <NUM> corresponding to the light transmission region 10a serves as the second mirror part <NUM>. The second mirror part <NUM> faces the first mirror part <NUM> via the void S in the direction D1. The second laminated body <NUM> is configured by alternately laminating a plurality of polysilicon layers and a plurality of silicon nitride layers one by one. An optical thickness of each of the polysilicon layers and the silicon nitride layers constituting the second mirror part <NUM> is preferably an integral multiple of <NUM>/<NUM> of the central transmission wavelength.

In the first laminated body <NUM> and the second laminated body <NUM>, a silicon oxide layer may be disposed instead of the silicon nitride layer. Further, in addition to the above-described materials, a titanium oxide, a tantalum oxide, a zirconium oxide, magnesium fluoride, an aluminum oxide, calcium fluoride, silicon, germanium, zinc sulfide and the like can be used as a material for each of the layers constituting the first laminated body <NUM> and the second laminated body <NUM>.

A plurality of through holes 54b extending from a surface 54a of the second laminated body <NUM> on the side opposite to the first intermediate layer <NUM> to the void S are formed in a portion of the second laminated body <NUM> corresponding to the void S. The plurality of through holes 54b are formed to such an extent that they do not substantially affect a function of the second mirror part <NUM>. The plurality of through holes 54b are used for removing a part of the first intermediate layer <NUM> by etching and forming the void S.

A first electrode <NUM> is formed in the first mirror part <NUM> to surround the light transmission region 10a. A second electrode <NUM> is formed in the first mirror part <NUM> to include the light transmission region 10a. That is, the first mirror part <NUM> includes the first electrode <NUM> and the second electrode <NUM>. The first electrode <NUM> and the second electrode <NUM> are formed by doping the polysilicon layer closest to the void S in the first laminated body <NUM> with impurities and reducing resistance. A third electrode <NUM> is formed on the second mirror part <NUM>. That is, the second mirror part <NUM> includes the third electrode <NUM>. The third electrode <NUM> faces the first electrode <NUM> and the second electrode <NUM> via the void S in a direction parallel to the line L. The third electrode <NUM> is formed by doping the polysilicon layer closest to the void S in the second laminated body <NUM> with impurities and reducing resistance. A size of the second electrode <NUM> is preferably a size including the entire light transmission region 10a, but may be substantially the same as that of the light transmission region 10a.

A pair of first terminals <NUM> and a pair of second terminals <NUM> are formed on the first layer structure <NUM>. The pair of first terminals <NUM> face each other with the light transmission region 10a interposed therebetween. Each of the first terminals <NUM> is disposed in a through hole which extends from the surface 54a of the second laminated body <NUM> to the first laminated body <NUM>. Each of the first terminals <NUM> is electrically connected to the first electrode <NUM> via a wiring 42a. The pair of second terminals <NUM> face each other with the light transmission region 10a interposed therebetween in a direction perpendicular to the direction in which the pair of first terminals <NUM> face each other. Each of the second terminals <NUM> is disposed in a through hole which extends from the surface 54a of the second laminated body <NUM> to the inside of the first intermediate layer <NUM>. Each of the second terminals <NUM> is electrically connected to the second electrode <NUM> via a wiring 43a, and is also electrically connected to the third electrode <NUM> via a wiring 44a.

Trenches <NUM> and <NUM> are provided in a surface 52a of the first laminated body <NUM> on the first intermediate layer <NUM> side. The trench <NUM> extends in an annular shape to surround a connection portion of the wiring 43a with the second terminal <NUM>. The trench <NUM> electrically insulates the first electrode <NUM> from the wiring 43a. The trench <NUM> extends in an annular shape along an inner edge of the first electrode <NUM>. The trench <NUM> electrically insulates the first electrode <NUM> from a region inside the first electrode <NUM> (that is, a region in which the second electrode <NUM> is present). A trench <NUM> is provided in the surface 54a of the second laminated body <NUM>. The trench <NUM> extends in an annular shape to surround the first terminal <NUM>. The trench <NUM> electrically insulates the first terminal <NUM> from the third electrode <NUM>. A region inside each of the trenches <NUM>, <NUM>, and <NUM> may be an insulating material or a void.

The second layer structure <NUM> is configured by laminating a second antireflection layer <NUM>, a third laminated body <NUM>, a second intermediate layer <NUM>, a the fourth laminated body <NUM> in this order on the second surface 41b. The second antireflection layer <NUM>, the third laminated body <NUM>, the second intermediate layer <NUM>, and the fourth laminated body <NUM> have the same configuration as the first antireflection layer <NUM>, the first laminated body <NUM>, the first intermediate layer <NUM>, and the second laminated body <NUM>, respectively. As described above, the second layer structure <NUM> has a laminated structure symmetrical with the first layer structure <NUM> with reference to the substrate <NUM>. That is, the second layer structure <NUM> is configured to correspond to the first layer structure <NUM>. The second layer structure <NUM> has a function of curbing warpage of the substrate <NUM> and the like.

An opening 60a is formed in the third laminated body <NUM>, the second intermediate layer <NUM>, and the fourth laminated body <NUM> to include the light transmission region 10a. A center line of the opening 60a coincides with the line L. The opening 60a is, for example, a cylindrical region and has a diameter substantially the same as that of the light transmission region 10a. The opening 60a is open to the light emitting side, and a bottom surface of the opening 60a reaches the second antireflection layer <NUM>. The opening 60a allows light transmitted through the first mirror part <NUM> and the second mirror part <NUM> to pass through.

A light-shielding layer <NUM> is formed on a surface of the fourth laminated body <NUM> on the light emitting side. The light-shielding layer <NUM> is made of, for example, aluminum or the like. A protective layer <NUM> is formed on a surface of the light-shielding layer <NUM> and an inner surface of the opening 60a. The protective layer <NUM> is made of, for example, an aluminum oxide. An optical influence due to the protective layer <NUM> can be ignored by setting a thickness of the protective layer <NUM> to <NUM> to <NUM> (preferably about <NUM>).

The Fabry-Perot interference filter <NUM> configured as described above has the pair of first mirror part <NUM> and second mirror part <NUM> which face each other via the void S, and a distance between the pair of mirror parts changes according to a potential difference generated between the pair of mirror parts (the first mirror part <NUM> and the second mirror part <NUM>). That is, in the Fabry-Perot interference filter <NUM>, a voltage (a driving voltage) is applied to the first electrode <NUM> and the third electrode <NUM> via the first terminal <NUM> and the second terminal <NUM>. The voltage causes the potential difference between the first electrode <NUM> and the third electrode <NUM>, and an electrostatic force corresponding to the potential difference is generated between the first electrode <NUM> and the third electrode <NUM>. The second mirror part <NUM> is attracted to the side of the first mirror part <NUM> fixed to the substrate <NUM> by the electrostatic force, and the distance between the first mirror part <NUM> and the second mirror part <NUM> is adjusted. As described above, in the Fabry-Perot interference filter <NUM>, the distance between the first mirror part <NUM> and the second mirror part <NUM> is variable.

A wavelength of light transmitted through the Fabry-Perot interference filter <NUM> depends on the distance between the first mirror part <NUM> and the second mirror part <NUM> in the light transmission region 10a. Therefore, the wavelength of the transmitted light can be appropriately selected by adjusting the voltage applied to the first electrode <NUM> and the third electrode <NUM>. As the potential difference between the first electrode <NUM> and the third electrode <NUM> becomes larger, the distance between the first mirror part <NUM> and the second mirror part <NUM> becomes smaller, and thus the wavelength of light transmitted through the Fabry-Perot interference filter <NUM> becomes shorter. The second electrode <NUM> has the same potential as the third electrode <NUM>. Therefore, the second electrode <NUM> serves as a compensation electrode which keeps the first mirror part <NUM> and the second mirror part <NUM> flat in the light transmission region 10a.

In the spectroscopic sensor 1A, for example, a spectroscopic spectrum can be obtained by detecting the intensity of light transmitted through the light transmission region 10a of the Fabry-Perot interference filter <NUM> with the light detector <NUM>, while the voltage applied to the Fabry-Perot interference filter <NUM> is changed (that is, the distance between the first mirror part <NUM> and the second mirror part <NUM> in the Fabry-Perot interference filter <NUM> is changed).

The spectroscopic sensor 1A has a structure for curbing generation of crosstalk noise in the detection signal of the light detector <NUM> due to the driving voltage applied to the Fabry-Perot interference filter <NUM>. Specifically, in the spectroscopic sensor 1A, a current path (a second current path) having a smaller electric resistance than that of an arbitrary current path (a first current path) from the Fabry-Perot interference filter <NUM> to the light detector <NUM> via the spacers <NUM> and the wiring substrate <NUM> is formed between the Fabry-Perot interference filter <NUM> and the stem <NUM> (the ground potential). Thus, when a driving voltage is applied to the Fabry-Perot interference filter <NUM>, most of the current component which will flow from the Fabry-Perot interference filter <NUM> to the wiring substrate <NUM> via the spacers <NUM> flows into the second current path. As a result, an amount of current reaching the light detector <NUM> via the first current path can be reduced, and the crosstalk noise in the detection signal can be curbed.

Before a specific structure of the spectroscopic sensor 1A is explained, first, a structure of a spectroscopic sensor <NUM> according to a comparative example will be described, and a mechanism by which the above-described crosstalk noise is generated in the spectroscopic sensor <NUM> will be described.

<FIG> is a schematic view showing a structure of a wiring substrate <NUM> and an electrical connection configuration between components in the spectroscopic sensor <NUM> according to the comparative example. The wiring substrate <NUM> has a structure in which a first insulating layer <NUM>, a silicon layer <NUM>, a second insulating layer <NUM>, and a passivation film <NUM> are laminated in this order from the stem <NUM> side. Each of the first insulating layer <NUM> and the second insulating layer <NUM> is a silicon thermal oxide film formed by heating a surface of the silicon layer <NUM>, and a thickness thereof is, for example, about <NUM>. The first insulating layer <NUM> is fixed to the inner surface 21a of the stem <NUM> via an adhesive layer <NUM> made of a non-conductive resin. The above-described wiring layers <NUM> and <NUM> are provided on a surface 113a of the second insulating layer <NUM> on the side opposite to the silicon layer <NUM>. A thickness of each of the wiring layers <NUM> and <NUM> is, for example, about <NUM>. Further, the passivation film <NUM> is formed on the surface 113a of the second insulating layer <NUM> to cover the surface 113a, a side surface of the light detector <NUM>, and a side surface of the temperature compensation element <NUM>. A thickness of the passivation film <NUM> is, for example, about <NUM>.

<FIG> is a view showing an equivalent circuit of the spectroscopic sensor <NUM>. In <FIG>, an electric resistance Ra is an electric resistance of a current path (a current path having a length from a portion P1 in which the wiring substrate <NUM> and the spacer <NUM> are in contact with each other to a portion P2 in which the wiring substrate <NUM> (the wiring layer <NUM>) and the light detector <NUM> are in contact with each other) in the first insulating layer <NUM> or the second insulating layer <NUM> in a direction (a direction D2) orthogonal to a thickness direction (the direction D1) of the wiring substrate <NUM>. An electric resistance Rb is an electric resistance of a current path which crosses the first insulating layer <NUM> or the second insulating layer <NUM> in the direction D1. An electric resistance Rc is an electric resistance of a current path (a current path having a length from the portion P1 to the portion P2) in the silicon layer <NUM> in the direction D2. An electrical resistance Rd is an electrical resistance of a current path which crosses the silicon layer <NUM> in the direction D1. An electrical resistance Re is an electrical resistance of a current path which crosses the adhesive layer <NUM> in the direction D1. Here, the electric resistance of each of the members (the first Insulating layer <NUM>, the silicon layer <NUM>, the second insulating layer <NUM>, and the adhesive layer <NUM>) is a value obtained by multiplying an electrical resistivity of the material of each of the members by "a length of each of the members÷a cross-sectional area of each of the members". Further, a thickness of each of the members (a length in the direction D1) is sufficiently smaller than the length from the portion P1 to the portion P2 in the direction D2. Further, a cross-sectional area of each of the members in the direction D1 is sufficiently smaller than a cross-sectional area of each of the members in the direction D2. Thus, "Ra>>Rb" and "Rc>>Rd" are established. Further, since the adhesive layer <NUM> is non-conductive, "Re>>Rc" is established. Further, since the resistivity of the silicon thermal oxide film (the first insulating layer <NUM>, and the second insulating layer <NUM>) is sufficiently larger than that of silicon (the silicon layer <NUM>), "Rb>>Rc" is established. Here, "A>>B" means that A is sufficiently (very) larger than B.

Since the driving voltage applied to the Fabry-Perot interference filter <NUM> is a high voltage, when the above-described driving voltage is applied to the Fabry-Perot interference filter <NUM>, a current component which flows from the Fabry-Perot interference filter <NUM> into the wiring substrate <NUM> via the spacer <NUM> is generated. Further, as described above, since a relationship of "Ra>>Rb>>Rc>>Rd" and "Re>>Rc" is established for the electric resistances Ra to Re, most of the current component will flow in a current path in a direction of an arrow shown in <FIG> (that is, a current path having the lowest electrical resistance). That is, most of the current component moves from the portion P1 in the second insulating layer <NUM> in the direction D1 to reach the silicon layer <NUM>, subsequently moves in the silicon layer <NUM> in the direction D2, subsequently moves in the second insulating layer <NUM> in the direction D1, and flows to the light detector <NUM> (the wiring layer <NUM>).

<FIG> is a view showing the crosstalk noise observed by the spectroscopic sensor <NUM> according to the comparative example. The inventor has observed the crosstalk noise as follows. That is, in a state in which light having a predetermined wavelength λ1 is continuously incident on the light transmission region 10a of the Fabry-Perot interference filter <NUM>, at a certain point in time t1, the driving voltage applied to the first electrode <NUM> and the third electrode <NUM> was changed from a voltage V0 (=0v) to a voltage Vλ1 in which light having a wavelength λ1 can be transmitted. As a result, it was confirmed that pulse-shaped crosstalk noise N was generated immediately after the driving voltage was changed from the voltage V0 to the voltage Vλ1. Although such crosstalk noise N is instantaneous, it may cause a problem according to a method of use (a measurement method) of the spectroscopic sensor <NUM>.

Next, with reference to <FIG>, the structure of the wiring substrate <NUM> and the electrical connection configuration between components in the spectroscopic sensor 1A will be described. The wiring substrate <NUM> has a structure in which a first insulating layer <NUM>, a silicon layer <NUM>, a second insulating layer <NUM>, a metal layer <NUM>, a third insulating layer <NUM> (an insulating layer), and a passivation film <NUM> are laminated in this order from the stem <NUM> side. The first insulating layer <NUM>, the silicon layer <NUM>, and the second insulating layer <NUM> are the same as the first insulating layer <NUM>, the silicon layer <NUM>, and the second insulating layer <NUM> in the spectroscopic sensor <NUM>. Therefore, the wiring substrate <NUM> is mainly different from the wiring substrate <NUM> in the spectroscopic sensor <NUM> in that the metal layer <NUM> and the third insulating layer <NUM> are provided between the second insulating layer <NUM> and the wiring layers <NUM> and <NUM>.

Each of the first insulating layer <NUM> and the second insulating layer <NUM> is a silicon thermal oxide film formed by heating a surface of the silicon layer <NUM>, and a thickness thereof is, for example, about <NUM>. The first insulating layer <NUM> is fixed to the inner surface 21a of the stem <NUM> via an adhesive layer made of a non-conductive resin (an adhesive layer similar to the adhesive layer <NUM>). The metal layer <NUM> is provided on a surface 73a of the second insulating layer <NUM> on the side opposite to the silicon layer <NUM>. In the embodiment, as an example, the metal layer <NUM> is provided on the entire surface 73a of the second insulating layer <NUM>. Further, the metal layer <NUM> is formed of a monolayer film made of Al. However, the metal layer <NUM> may be formed of a material other than the above-described material, and may be formed of, for example, a single layer film of a metal material (for example, Au or the like) other than Al or a laminated film of Ti-Pt-Au, Ti-Ni-Au, Cr-Au or the like. A thickness of the metal layer <NUM> is, for example, about <NUM>.

The third insulating layer <NUM> has a first surface 75a which is a main surface 3a of the wiring substrate <NUM>, and a second surface 75b on the side opposite to the first surface 75a. The third insulating layer <NUM> is formed of, for example, a material such as TEOS, SiN, SiO<NUM>, BPSG, an SOG film (glass), polyimide, or an insulating resin. A thickness of the third insulating layer <NUM> is, for example, about <NUM>. The wiring layers <NUM> and <NUM> and the electrode pads <NUM> and <NUM> described above are provided on the first surface 75a side of the third insulating layer <NUM>. On the other hand, the metal layer <NUM> is provided on the second surface 75b side of the third insulating layer <NUM>. That is, the wiring layers <NUM> and <NUM>, the electrode pads <NUM> and <NUM>, and the metal layer <NUM> are insulated by the third insulating layer <NUM>. Thus, the light detector <NUM> and the metal layer <NUM> are insulated from each other. The passivation film <NUM> is formed on the first surface 75a of the third insulating layer <NUM> to cover the first surface 75a, the side surface of the light detector <NUM>, and the side surface of the temperature compensation element <NUM>. A thickness of the passivation film <NUM> is, for example, about <NUM>.

An opening part 75c which exposes a surface 74a of the metal layer <NUM> on the third insulating layer <NUM> side is formed in the third insulating layer <NUM>. An opening part 76a which communicates with the opening part 75c is also in the passivation film <NUM>. Thus, a part of the surface 74a of the metal layer <NUM> is exposed to the outside in at least a part of a region on the wiring substrate <NUM>. Further, as shown in <FIG>, <FIG> and <FIG>, a part of the surface 74a of the metal layer <NUM> and the inner surface 21a of the stem <NUM> are electrically connected by a wire <NUM> (a connecting member). In the embodiment, a bonding pad 91a (a connecting member) electrically connected to a part of the surface 74a of the metal layer <NUM> is provided inside the opening part 75c and the opening part 76a. Additionally, one end of the wire <NUM> is connected to the bonding pad 91a. On the other hand, the other end of the wire <NUM> is connected to the inner surface 21a of the stem <NUM>. In the embodiment, as an example, the metal layer <NUM> and the stem <NUM> are electrically connected to each other via the wire <NUM> and the bonding pad 91a at two locations on the wiring substrate <NUM>. Specifically, when seen in the direction D1, the opening part 75c, the opening part 76a, and the bonding pad 91a are provided at each of positions (two corners of the rectangular wiring substrate <NUM>) adjacent to each of the plurality of spacers <NUM>. Then, each of the bonding pads 91a is electrically connected to the inner surface 21a of the stem <NUM> adjacent to each of the bonding pads 91a via a wire <NUM>. Thus, the current component which flows from the Fabry-Perot interference filter <NUM> to the wiring substrate <NUM> via each of the spacers <NUM> can be appropriately released to the stem <NUM>. The metal layer <NUM> and the stem <NUM> may be connected to each other by the wire <NUM> and the bonding pad 91a at one location or three or more locations.

In the above-described spectroscopic sensor 1A, the Fabry-Perot interference filter <NUM> and the light detector <NUM> are separated by the spacers <NUM>. Thus, a distance between the Fabry-Perot interference filter <NUM> and the light detector <NUM> can be increased. As a result, crosstalk noise in the detection signal of the light detector <NUM> due to the driving voltage applied to the Fabry-Perot interference filter <NUM> is curbed. Further, in the spectroscopic sensor 1A, a current path (the second current path) having a smaller electric resistance than that of an arbitrary current path from the Fabry-Perot interference filter <NUM> to the light detector <NUM> via the spacers <NUM> and the wiring substrate <NUM> is formed between the Fabry-Perot interference filter <NUM> and the stem <NUM> (the ground potential). In the embodiment, a current path from the Fabry-Perot interference filter <NUM> to the stem <NUM> via the spacers <NUM>, the third insulating layer <NUM>, the metal layer <NUM>, the bonding pad 91a, and the wire <NUM> corresponds to the second current path. Therefore, the current component which flows from the Fabry-Perot interference filter <NUM> to the spacers <NUM> is more likely to flow to the stem <NUM> than to the light detector <NUM>. Thus, the crosstalk noise caused by the current component flowing from the Fabry-Perot interference filter <NUM> to the light detector <NUM> via the spacers <NUM> and the wiring substrate <NUM> is curbed. Accordingly, according to the spectroscopic sensor 1A, the crosstalk noise in the detection signal of the light detector <NUM> can be effectively curbed.

Further, the spectroscopic sensor 1A includes a conductive connecting member (in the embodiment, the wire <NUM> and the bonding pad 91a) which electrically connects the wiring substrate <NUM> to the stem <NUM> so that the current component flowing from the Fabry-Perot interference filter <NUM> to the spacer <NUM> is released to the stem <NUM>. According to the configuration, the current component flowing from the Fabry-Perot interference filter <NUM> to the spacer <NUM> can be appropriately released to the stem <NUM> via the conductive connecting member. More specifically, the connecting member (the wire <NUM> and the bonding pad 91a) electrically connects a region (the metal layer <NUM> in the embodiment) along the main surface 3a of the wiring substrate <NUM> to the stem <NUM>. Additionally, the second current path is a path which extends from the Fabry-Perot interference filter <NUM> to the stem <NUM> via the spacer <NUM>, the region (the metal layer <NUM>) along the main surface 3a, and the connecting member (the wire <NUM> and the bonding pad 91a). According to the configuration, the current component which will flow to the light detector <NUM> via the wiring substrate <NUM> can be appropriately released to the stem <NUM> via the connecting member (the wire <NUM> and the bonding pad 91a).

Further, the wiring substrate <NUM> includes the third insulating layer <NUM> having the first surface 75a as the main surface 3a and the second surface 75b on the side opposite to the first surface 75a, the wiring layer <NUM> provided on the first surface 75a side of the third insulating layer <NUM> and on which the light detector <NUM> is mounted, and the metal layer <NUM> provided on the second surface 75b side of the third insulating layer <NUM>. According to the configuration, while the insulation between the light detector <NUM> and the metal layer <NUM> is ensured by the third insulating layer <NUM>, the current component which will flow to the light detector <NUM> can be appropriately released to the stem <NUM> via the metal layer <NUM>.

Further, the opening part 75c which exposes the surface 74a of the metal layer <NUM> is formed in the third insulating layer <NUM>. The connecting member (the wire <NUM> and the bonding pad 91a) is connected to the metal layer <NUM> via the opening part 75c and connected to the stem <NUM>. According to the configuration, the metal layer <NUM> and the stem <NUM> can be appropriately and easily connected by the wire bonding. A length of the wire <NUM> which connects the bonding pad 91a to the stem <NUM> can be shortened, and interference between the wire <NUM> and the other wires <NUM> can be easily avoided by providing the opening part 75c (that is, the bonding pad 91a) as close as possible to an outer edge portion of the wiring substrate <NUM> (an edge portion of the wiring substrate <NUM> when seen in the direction D1) as in the embodiment.

In the first embodiment, the metal layer <NUM> is provided on the entire surface 73a of the second insulating layer <NUM>, but a metal layer provided only on a part of the surface 73a of the second insulating layer <NUM> may be adopted. For example, as shown in <FIG> and <FIG>, metal layers 74A to 74D may be provided instead of the metal layer <NUM>. In this case, the third insulating layer <NUM> is directly provided on the second insulating layer <NUM> in the portion in which the metal layers 74A to 74D are not provided.

The two metal layers 74A shown in (A) of <FIG> is provided to overlap the region on the wiring substrate <NUM> in which the spacer <NUM> is provided (in other words, the region in which the spacers <NUM> and the wiring substrate <NUM> are in contact with each other via an adhesive resin or the like) when seen in the direction D1. As an example, the metal layer 74A is provided for each of the spacers <NUM>. Specifically, each of the metal layers 74A is provided in a rectangular region including the region in which the spacer <NUM> is provided when seen in the direction D1. The above-described opening part 75c and opening part 76a (refer to <FIG>), and the bonding pad 91a connected to the metal layer 74A are provided in a portion of each of the metal layers 74A which does not overlap the spacers <NUM>. According to the configuration, the current component which flows from the Fabry-Perot interference filter <NUM> to the wiring substrate <NUM> via the spacer <NUM> can be appropriately released to the stem <NUM> via the metal layer 74A provided in a region directly below the spacers <NUM>. More specifically, the current component which flows from a bottom surface of the spacer <NUM> to the wiring substrate <NUM> can be reliably captured by the metal layer 74A provided in the region directly below the spacers <NUM>. As a result, the current component can be appropriately induced to the stem <NUM>.

The metal layer 74B shown in (B) of <FIG> is provided to overlap an arbitrary current path between the region in which the spacer <NUM> is provided and the light detector <NUM> when seen in the direction D1 (in this embodiment, an arbitrary current path between the region in which the spacer <NUM> is provided and the wiring layer <NUM>). That is, the metal layer 74B is formed to have a portion which divides the arbitrary current path between the region in which the spacer <NUM> is provided and the light detector <NUM> when seen in the direction D1. As an example, the metal layer 74B is formed to cover a region including the wiring layer <NUM> with respect to each of spacers <NUM> when seen in the direction D1. Thus, the current component which will flow from the region in which the spacer <NUM> is provided to the light detector <NUM> can be appropriately captured by the metal layer 74B and released to the stem <NUM>. Here, as an example, the bonding pad 91a connected to the metal layer 74B via the above-described opening part 75c and opening part 76a (refer to <FIG>) is provided at two locations corresponding to both ends of the metal layer 74B.

The metal layer 74C shown in (A) of <FIG> is provided in a region other than the rectangular region including the wiring layer <NUM> (here, the region including the wiring layer <NUM> and the electrode pad <NUM>). Further, the above-described opening part 75c and opening part 76a (refer to <FIG>), and the bonding pad 91a connected to the metal layer 74C are provided in a region in which the metal layer 74C and the spacer <NUM> do not overlap (here, two places as an example). Like the metal layer 74A, the metal layer 74C has a portion which overlaps the region in which the spacer <NUM> is provided in the wiring substrate <NUM> when seen in the direction D1. Further, like the metal layer 74B, the metal layer 74C has a portion which divides the arbitrary current path extending from the region in which the spacer <NUM> is provided to the light detector <NUM> when seen in the direction D1. Therefore, according to the metal layer 74C, the above-described effects of both the metal layer 74A and the metal layer 74B are exhibited.

The two metal layers 74D shown in (B) of <FIG> are provided in an extending direction of each of the spacers <NUM> (a direction orthogonal to a direction in which the spacers <NUM> face each other) to divide the arbitrary current path between the region in which each of the spacers <NUM> is provided and the light detector <NUM> when seen in the direction D1. The above-described opening part 75c and opening part 76a (refer to <FIG>) and the bonding pad 91a connected to the metal layer 74D are provided at an end portion of each of the metal layers 74D. The same effect as that of the above-described metal layer 74B can be obtained by such two metal layers 74D.

The above-described effects exhibited by the metal layers 74A to 74D are similarly exhibited by the metal layer <NUM> provided on the entire surface 73a of the second insulating layer <NUM>. On the other hand, the metal layers 74A to 74D are provided not to overlap the light detector <NUM> when seen in the direction D1. More specifically, the metal layers 74A to 74D are provided not to overlap the wiring layer <NUM> electrically connected to the light detector <NUM> when seen in the direction D1. In this configuration, the wiring layer <NUM> and the metal layers 74A to 74D do not have portions which face each other in the direction D1. That is, the metal layers 74A to 74D are formed so that the wiring layer <NUM> and the metal layers 74A to 74D do not come close to each other with the third insulating layer <NUM> interposed therebetween. Thus, a parasitic capacitance generated in the wiring layer <NUM> can be appropriately curbed, and an influence of the parasitic capacitance on the light detector <NUM> can be curbed. As a result, it is possible to curb a decrease in a response speed of the detection signal of the light detector <NUM> due to the parasitic capacitance.

The metal layer 74B shown in (B) of <FIG> and the metal layer 74D shown in (B) of <FIG> do not overlap the spacer <NUM> when seen in the direction D1. Thus, there is a possibility that some of the current component flowing from the bottom surface of the spacer <NUM> to the wiring substrate <NUM> moves in the second insulating layer <NUM> and the third insulating layer <NUM> and flows into the silicon layer <NUM> in the region directly below the spacer <NUM>. Therefore, in order to enhance the effect of reducing the crosstalk noise, parts of the metal layers 74B and 74D may be brought into contact with the silicon layer <NUM> by providing an opening in a part of the second insulating layer <NUM> located between the metal layers 74B and 74D and the silicon layer <NUM>. Thus, even when some of the current component flows into the silicon layer <NUM> as described above, some of the current component can be appropriately released from a contact portion between the silicon layer <NUM> and the metal layers 74B and 74D to the metal layers 74B and 74C. As a result, the current component which flows from the Fabry-Perot interference filter <NUM> to the light detector <NUM> can be appropriately curbed, and the crosstalk noise in the detection signal of the light detector <NUM> can be curbed more effectively.

As shown in <FIG> and <FIG>, a spectroscopic sensor 1B is different from the spectroscopic sensor 1A in that a wiring substrate 3B is included instead of the wiring substrate <NUM>, and a conductive resin material <NUM> is provided instead of the wire <NUM> and the bonding pad 91a. The wiring substrate 3B is different from the wiring substrate <NUM> in that a third insulating layer 75B and a passivation film 76B are provided instead of the third insulating layer <NUM> and the passivation film <NUM>. The metal layer <NUM> is provided to span an edge portion of the wiring substrate 3B as seen in the direction D1. That is, the metal layer <NUM> is provided at least on the edge portion of the wiring substrate 3B. Further, a portion of the metal layer <NUM> provided at the edge portion of the wiring substrate 3B is exposed to the outside. In the embodiment, as an example, an opening part <NUM> (a notch) is formed by removing a part of an edge portion of the third insulating layer 75B, and an opening part <NUM> (notch) continuous with the opening part <NUM> is formed by removing a part of an edge portion of the passivation film 76B. A part of the metal layer <NUM> is exposed to the outside by forming an opening part <NUM> including the opening part <NUM> and the opening part <NUM>. In the spectroscopic sensor 1B, a part of the metal layer <NUM> exposed in the opening part <NUM> and the inner surface 21a of the stem <NUM> are electrically connected by the conductive resin material <NUM>. The conductive resin material <NUM> is provided to cover the edge portion of the wiring substrate 3B, and is in contact with both a part of the metal layer <NUM> and the inner surface 21a of the stem <NUM>. The conductive resin material <NUM> is, for example, a conductive silver paste, a conductive carbon paste, or the like.

In the embodiment, a current path from the Fabry-Perot interference filter <NUM> to the stem <NUM> via the spacer <NUM>, the third insulating layer 75B, the metal layer <NUM>, and the conductive resin material <NUM> corresponds to the second current path. According to the spectroscopic sensor 1B, the metal layer <NUM> and the stem <NUM> can be appropriately and easily connected by providing the conductive resin material <NUM> to cover the edge portion of the wiring substrate 3B.

Also in the spectroscopic sensor 1B, like the spectroscopic sensor 1A, a metal layer provided only on a part of the surface 73a of the second insulating layer <NUM> may be adopted instead of the metal layer <NUM>. For example, as shown in <FIG> and <FIG>, metal layers 74E to <NUM> may be provided instead of the metal layer <NUM>.

Two metal layers 74E shown in (A) of <FIG> have a configuration similar to that of the above-described metal layer 74A. That is, each of the metal layers 74E is provided to overlap the region on the wiring substrate <NUM> in which each of the spacers <NUM> is provided when seen in the direction D1. Each of the metal layers 74E extends to an edge portion (here, a corner portion) of the wiring substrate 3B, and the opening part <NUM> is formed in the corner portion. In the opening part <NUM>, a part of a surface 74a of each of the metal layers 74E is exposed. The conductive resin material <NUM> is provided to cover the exposed surface 74a. According to the configuration, similar to the metal layer 74A, the current component which flows from the Fabry-Perot interference filter <NUM> to the wiring substrate <NUM> via the spacer <NUM> can be appropriately released to the stem <NUM> via the metal layer 74E provided in the region directly below the spacer <NUM>. More specifically, the current component which flows from the bottom surface of the spacer <NUM> to the wiring substrate <NUM> can be reliably captured by the metal layer 74E provided in the region directly below the spacer <NUM>. As a result, the current component can be appropriately induced to the stem <NUM>.

The metal layer 74F shown in (B) of <FIG> has a configuration similar to that of the above-described metal layer 74B. That is, the metal layer 74F is provided to overlap an arbitrary current path between the region in which the spacer <NUM> is provided and the light detector <NUM> when seen in the direction D1. Thus, the current component which will flow from the region in which the spacer <NUM> is provided to the light detector <NUM> can be appropriately captured by the metal layer 74F and can be released to the stem <NUM>. Here, as an example, the opening part <NUM> is formed at each of two corners of the wiring substrate 3B, and a part of the surface 74a of the metal layer 74F is exposed at each of the opening parts <NUM>. The conductive resin material <NUM> is provided to cover the exposed surface 74a.

The metal layer <NUM> shown in (C) of <FIG> has a configuration similar to that of the above-described metal layer 74C. That is, the metal layer <NUM> is provided in a region other than a rectangular region including the wiring layer <NUM> (here, the region including the wiring layer <NUM> and the electrode pad <NUM>). Further, the opening part <NUM> is formed in a region in which the metal layer 74C and the spacer <NUM> do not overlap (here, as an example, two corners of the wiring substrate 3B), and a part of the surface 74a of the metal layer <NUM> is exposed in each of the opening parts <NUM>. The conductive resin material <NUM> is provided to cover the exposed surface 74a. According to such a metal layer <NUM>, the above-described effects of both the metal layer 74E and the metal layer 74F are exhibited.

Two metal layers <NUM> shown in (D) of <FIG> have a configuration similar to that of the above-described metal layer 74D. That is, the metal layer <NUM> is provided in the extending direction of each of the spacers <NUM> (the direction orthogonal to the direction in which the spacers <NUM> face each other) to divide an arbitrary current path between the region in which each of the spacers <NUM> is provided and the light detector <NUM> when seen in the direction D1. The opening part <NUM> is formed at an end portion of each of the metal layers <NUM> (an edge portion of the wiring substrate 3B), and a part of the surface 74a of the metal layer <NUM> is exposed at each of the opening parts <NUM>. The conductive resin material <NUM> is provided to cover the exposed surface 74a. The two metal layers <NUM> also have the same effect as the above-described metal layer 74E.

Further, the metal layers 74E to <NUM> are provided not to overlap the wiring layer <NUM> when seen in the direction D1, like the metal layers 74A to 74D. Thus, the parasitic capacitance generated in the wiring layer <NUM> can be appropriately curbed. As a result, it is possible to curb a decrease in the response speed of the detection signal of the light detector <NUM> due to the parasitic capacitance. Further, as in the case in which the above-described metal layer 74B or metal layer 74D is used, when the metal layer 74F or the metal layer <NUM> is used, parts of the metal layers 74F and <NUM> may be brought into contact with the silicon layer <NUM> by providing an opening in a part of the second insulating layer <NUM> located between the metal layers 74F and <NUM> and the silicon layer <NUM> to enhance the effect of reducing the crosstalk noise.

As shown in <FIG> and <FIG>, a spectroscopic sensor 1C is different from the spectroscopic sensor <NUM> in that a wiring substrate 3C is included instead of the wiring substrate <NUM> and connecting members (the wire <NUM> and the bonding pad 91b) are further included. The wiring substrate 3C is different from the wiring substrate <NUM> in that a metal layer 74I provided between the second insulating layer <NUM> and the spacer <NUM> is included. In the embodiment, as an example, a metal layer 74I is formed in a region which includes the spacer <NUM> and has a size larger than the spacer <NUM> when seen in the direction D1. However, the metal layer 74I may be formed to have substantially the same size as the bottom surface of the spacer <NUM> (the surface which faces the wiring substrate 3C). The metal layer 74I is formed of, for example, a laminated film made of Cr-Pt-Au, similarly to the wiring layer <NUM>. However, the metal layer 74I may be formed of a material other than the above-described material and may be formed of, for example, a single-layer film such as Al or Au, or a laminated film such as Ti-Pt-Au, Ti-Ni-Au or Cr-Au.

In the spectroscopic sensor 1C, the bonding pad 91b is provided in a portion of the metal layer 74I in which the spacer <NUM> is not disposed. Additionally, the bonding pad 91b and the inner surface 21a of the stem <NUM> are electrically connected by the wire <NUM>. In the embodiment, a current path which extends from the Fabry-Perot interference filter <NUM> to the stem <NUM> via the spacer <NUM>, the metal layer 74I, the bonding pad 91b, and the wire <NUM> corresponds to the second current path. According to the configuration, the current component which flows from the Fabry-Perot interference filter <NUM> to the wiring substrate 3C via the spacer <NUM> can be preferably released to the stem <NUM> from the metal layer 74I provided in the region directly below the spacer <NUM>. More specifically, the current component which flows from the bottom surface of the spacer <NUM> into the wiring substrate 3C can be reliably captured by the metal layer 74I provided in the region directly below the spacer <NUM>. As a result, the current component can be appropriately induced to the stem <NUM>. Further, a manufacturing process of the wiring substrate 3C can be simplified by providing the metal layer 74I for releasing the current component to the stem <NUM> on the same layer as the wiring layer <NUM> (on the surface 73a of the second insulating layer <NUM>). Specifically, as compared with the spectroscopic sensors 1A and 1B described above, the process is simplified by an amount that steps of forming the metal layer <NUM> and the third insulating layers <NUM> and 75B can be omitted.

As shown in <FIG> and <FIG>, a spectroscopic sensor 1D includes a wiring substrate 3D having the same configuration as that of the wiring substrate <NUM>. On the other hand, the spectroscopic sensor 1D includes a spacer 6A having a region for wire bonding (a region required for providing the bonding pad 91c). As an example in the embodiment, the region is a portion of an upper surface 6a of the spacer 6A supporting the Fabry-Perot interference filter <NUM> which does not overlap the Fabry-Perot interference filter <NUM> when seen in the direction D1. The bonding pad 91c is provided in the above-described region. Then, the bonding pad 91c and the inner surface 21a of the stem <NUM> are electrically connected by the wire <NUM>. That is, the spectroscopic sensor 1D includes a connecting member (the bonding pad 91c and the wire <NUM>) which electrically connects the upper surface 6a of the spacer 6A to the inner surface 21a of the stem <NUM>. In the embodiment, a current path from the Fabry-Perot interference filter <NUM> to the stem <NUM> via the spacer 6A, the bonding pad 91c, and the wire <NUM> corresponds to the second current path. Therefore, according to the configuration, before the current component which flows from the Fabry-Perot interference filter <NUM> to the spacer 6A reaches the wiring substrate 3D, the current component can be appropriately released from the spacer 6A to the stem <NUM>. In the embodiment, the bonding pad 91c is provided on the upper surface 6a of the spacer 6A, but the bonding pad 91c may be provided on another place (for example, a side surface of the spacer 6A). That is, a portion (for example, a side surface) other than the upper surface 6a of the spacer 6A and the stem <NUM> may be electrically connected. Further, a part (for example, a side surface) of the spacer 6A and the stem <NUM> may be connected by a connecting member similar to the above-described conductive resin material <NUM> instead of the bonding pad and the wire.

As shown in <FIG> and <FIG>, a spectroscopic sensor 1E is different from the spectroscopic sensor 1D in that a metal film <NUM> disposed on the upper surface 6a of the spacer 6A is further included, and the bonding pad 91c is provided on a metal film <NUM>. In the spectroscopic sensor 1E, the metal film <NUM> is disposed between the upper surface 6a of the spacer 6A and the Fabry-Perot interference filter <NUM>. The metal film <NUM> has a portion which does not overlap the Fabry-Perot interference filter <NUM> when seen in the direction D1, and the bonding pad 91c is provided in the portion. The metal film <NUM> is formed on the upper surface 6a by forming a single-layer film of a metal material (for example, Au or the like) or a laminated film of Ti-Pt-Au, Ti-Ni-Au, Cr-Au or the like by vapor deposition or sputtering, for example. The connecting member (the bonding pad 91c and the ire <NUM>) electrically connects the spacer 6A to the inner surface 21a of the stem <NUM> via the metal film <NUM>. In the embodiment, a current path which extends from the Fabry-Perot interference filter <NUM> to the stem <NUM> via the metal film <NUM>, the bonding pad 91c, and the wire <NUM> corresponds to the second current path. Therefore, according to the configuration, the current component which flows from the Fabry-Perot interference filter <NUM> toward the spacer 6A can be appropriately released from the metal film <NUM> to the stem <NUM> before it reaches the spacer 6A. The metal film <NUM> may be provided on the side surface of the spacer 6A, and the metal film <NUM> and the inner surface 21a of the stem <NUM> may be electrically connected by the connecting member (the bonding pad and the wire, or the conductive resin material). In this case, the current path which extends from the Fabry-Perot interference filter <NUM> to the stem <NUM> via the spacer 6A, the metal film <NUM>, and the connecting member corresponds to the second current path.

As shown in <FIG>, a spectroscopic sensor 1F is different from the spectroscopic sensor <NUM> in that a wiring substrate 3F is provided instead of the wiring substrate <NUM>. The wiring substrate 3F is different from the wiring substrate <NUM> in a point that the first insulating layer <NUM> is removed and a point that a surface of the silicon layer <NUM> (the second layer) on the side opposite to the second insulating layer <NUM> (the first layer) comes into contact with the inner surface 21a of the stem <NUM> via an adhesive layer <NUM> (a connecting member) made of a conductive resin. That is, the wiring substrate 3F includes a second insulating layer <NUM> having a surface 73a (a first surface) as the main surface 3a and a back surface 73b (a second surface) on the side opposite to the surface 73a, and a silicon layer <NUM> provided on the back surface 73b side of the second insulating layer <NUM>. The adhesive layer <NUM> is disposed between the surface of the silicon layer <NUM> on the side opposite to the second insulating layer <NUM> and the inner surface 21a of the stem <NUM> and electrically connects the surface of the silicon layer <NUM> on the side opposite to the second insulating layer <NUM> to the inner surface 21a of the stem <NUM>.

<FIG> is a view showing an equivalent circuit of the spectroscopic sensor 1F. From a relationship between the equivalent circuit and the above-described electric resistance, it can be seen that the electrical resistance of the current path extending from the spacer <NUM> toward the stem <NUM> via the second insulating layer <NUM> and the silicon layer <NUM> is smaller than that of the current path extending from the spacer <NUM> to the light detector <NUM> via at least one of the second insulating layer <NUM> and the silicon layer <NUM>. That is, the current path in a direction of an arrow shown in <FIG> corresponds to the second current path. Specifically, in the spectroscopic sensor 1F, the current path which extends from the Fabry-Perot interference filter <NUM> to the stem <NUM> via the spacer <NUM>, the second insulating layer <NUM>, the silicon layer <NUM>, and the adhesive layer <NUM> corresponds to the second current path. According to the configuration, the current component which flows from the Fabry-Perot interference filter <NUM> to the wiring substrate 3F via the spacer <NUM> can be appropriately released to the stem <NUM> by passing through the inside of the wiring substrate 3F (the second insulating layer <NUM> and the silicon layer <NUM>).

In the above-described embodiment, although the first layer is the second insulating layer <NUM> made of a silicon thermal oxide film, and the second layer is the silicon layer <NUM> made of silicon, the first layer and the second layer need only have the above-described relationship (that is, relationship that "the electrical resistance of the current path from the spacer <NUM> to the stem <NUM> via the first layer and the second layer is smaller than the electrical resistance of the current path from the spacer <NUM> to the light detector <NUM> via at least one of the first layer and the second layer"), and materials of the first layer and the second layer are not limited to the above examples. Further, the first layer or the second layer may be a layer in which a plurality of layers are grouped. That is, the first layer or the second layer may include a plurality of layers (for example, a layer formed of a plurality of different materials).

<FIG> is a view showing measurement results of the crosstalk noise in the example (the spectroscopic sensor 1F) and the comparative example (the spectroscopic sensor <NUM>). The measurement is performed by changing the driving voltage applied to the first electrode <NUM> and the third electrode <NUM> from <NUM> V to a voltage capable of transmitting light having a predetermined wavelength at a certain point in time (here, a point in time after <NUM> seconds from the start of measurement) in a state in which light having a predetermined wavelength is continuously incident on the light transmission region 10a of the Fabry-Perot interference filter <NUM>. As a result, in the comparative example, the crosstalk noise having a magnitude of about <NUM>. 5V was generated, whereas in the embodiment, the crosstalk noise could be curbed to a magnitude of about <NUM>. It is considered that such a crosstalk noise reduction effect is obtained by forming the second current path having a smaller electrical resistance than that of the arbitrary first current path extending from the Fabry-Perot interference filter <NUM> to the light detector <NUM> via the spacer and the wiring substrate between the Fabry-Perot interference filter <NUM> and the stem <NUM> (that is, by guiding the current component flowing from the Fabry-Perot interference filter <NUM> to the wiring substrate via the spacer to the stem <NUM> instead of the light detector <NUM>). Therefore, it is considered that the same crosstalk noise reduction effect can also be obtained in the spectroscopic sensors 1A to 1E in which the second current path (that is, the path through which the current component from the Fabry-Perot interference filter <NUM> is positively released to the stem <NUM>) is formed as in the spectroscopic sensor 1F.

Although some embodiments of the disclosure have been described above, the disclosure is not limited to the above-described embodiments, a part of the configuration in the above-described one embodiment or modified example can be arbitrarily applied to the configuration in another embodiment or modified example. For example, in order to reduce the current component flowing from the Fabry-Perot interference filter <NUM> to the light detector <NUM> as much as possible and to enhance the crosstalk noise reduction effect, some of the above-described embodiments may be combined as appropriate. For example, a configuration (for example, one of the first to third embodiments) in which a region (the metal layers <NUM>, and 74A to 74I) along the main surface 3a of the wiring substrate and the stem <NUM> are electrically connected, and a configuration (for example, the fourth or fifth embodiment) in which the spacer 6A and the stem <NUM> are electrically connected may be combined. A current path for releasing the current component from the Fabry-Perot interference filter <NUM> to the stem <NUM> (a path having a smaller electric resistance than that of the current path extending from the Fabry-Perot interference filter <NUM> to the light detector <NUM>) can be provided in multiple stages by combining a plurality of configurations. As a result, the current component which affects the light detector <NUM> can be reduced as much as possible, and the crosstalk noise can be curbed even more effectively.

Further, in the above-described embodiment, although the stem <NUM> is used as a ground part (a guidance destination of the current component from the Fabry-Perot interference filter <NUM>) connected to the ground potential, a member other than the stem <NUM> may be used as the ground part. For example, in the first embodiment, the wire <NUM> may be directly connected to the lead pin 8A connected to the ground potential. In this case, the lead pin 8A serves as the ground part.

Claim 1:
A light detection device (1A) comprising:
a mounting substrate having a main surface (3a);
a light detector (<NUM>) disposed on the main surface of the mounting substrate;
a Fabry-Perot interference filter (<NUM>) configured so that a distance between a pair of mirror parts (<NUM>, <NUM>) changes due to an electrostatic force by forming a gap between the pair of mirror parts (<NUM>, <NUM>) facing each other;
a support member (<NUM>, 6A) provided on the main surface (3a) of the mounting substrate and configured to support the Fabry-Perot interference filter (<NUM>) so that the Fabry-Perot interference filter (<NUM>) and the light detector (<NUM>) are separated from each other; and
a ground part connectable to a ground potential,
wherein a second current path having a smaller electrical resistance than that of an arbitrary first current path extending from the Fabry-Perot interference filter (<NUM>) to the light detector (<NUM>) via the support member (<NUM>, 6A) and the mounting substrate is formed between the Fabry-Perot interference filter (<NUM>) and the ground part, and
the second current path is configured to release a current component, which flows from the Fabry-Perot interference filter (<NUM>) to the support member (<NUM>, 6A), to the ground part.