JP5862754B2 - Pulse sensor and pulse meter - Google Patents

Description

The present invention relates to a pulse sensor, a pulse meter, and the like.

  In fields such as medicine, agriculture, and the environment, a spectroscopic sensor is used for diagnosing and inspecting an object. For example, in the medical field, a pulse oximeter that measures blood oxygen saturation using light absorption of hemoglobin is used. In the field of agriculture, a sugar content meter that measures the sugar content of fruits using light absorption of sugar is used.

JP-A-6-129908 JP 2006-351800 A

  However, the conventional spectral sensor has a problem that it is difficult to reduce the size. For example, in a spectroscopic sensor that acquires a continuous spectrum, it is necessary to provide a prism or the like for generating a continuous spectrum or to secure an optical path length, so that the apparatus becomes large. For this reason, it becomes difficult to install a large number of sensors or to always install the sensors on the inspection object.

  Here, Patent Document 1 discloses a technique for limiting the transmission wavelength band of a filter by limiting the incident angle of incident light using an optical fiber. Patent Document 2 discloses a technique for sensing light in a plurality of wavelength bands using multilayer filters having different film thicknesses for each sensor.

  According to some aspects of the present invention, it is possible to provide a spectroscopic sensor, an electronic device, and the like that can be miniaturized.

  One embodiment of the present invention is a light source unit that irradiates light in a wavelength band including a plurality of wavelengths to be detected, and a spectral sensor that receives light obtained by irradiating the observation target with light from the light source unit The spectroscopic sensor includes a plurality of optical bandpass filters having different transmission wavelengths and a plurality of photosensor units, and the first optical bandpass filter among the plurality of optical bandpass filters. Has a wavelength characteristic that transmits the first specific wavelength, and the second optical bandpass filter of the plurality of optical bandpass filters has a second specific wavelength different from the first specific wavelength. A first photosensor of the plurality of photosensors that senses light of the first specific wavelength that has passed through the first optical bandpass filter, and transmits the plurality of photosensors. Second photosensor of photosensors is related to the spectroscopic sensor device for sensing the light of the second of the second specific wavelength transmitted through the optical band-pass filter.

  According to one embodiment of the present invention, light obtained by irradiating the observation target with light from the light source unit enters the spectroscopic sensor. Then, the first specific wavelength light transmitted through the first optical bandpass filter is sensed by the first photosensor, and the second specific wavelength light transmitted through the second optical bandpass filter is second. Sensed by photo sensor. As a result, the spectral sensor device can be reduced in size.

  In one embodiment of the present invention, when reflected light obtained by irradiating the observation target with light from the light source unit is incident on the spectroscopic sensor, the spectroscopic sensor does not pass through the observation target from the light source unit. A light shielding member that shields light incident on the sensor may be included.

  If it does in this way, the light which injects into a spectroscopic sensor from a light source part will be shielded without passing through an observation object, and the reflected light obtained by irradiating the observation object with the light from a light source part can enter into a spectroscopic sensor.

  In one embodiment of the present invention, the light source unit emits light so as to cross a facing surface facing the observation target, and the spectroscopic sensor receives light incident across the facing surface, The light shielding member may be provided between the light source unit and the spectral sensor.

  In this way, by providing the light blocking member between the light source unit and the spectroscopic sensor, it is possible to block light incident on the spectroscopic sensor from the light source unit without passing through the observation target.

  In the aspect of the invention, the plurality of photosensor units may be arranged in an array on the first direction side of the light source unit in a plan view with respect to the facing surface facing the observation target.

  As described above, a plurality of photosensor units are arranged in an array on the first direction side of the light source unit, so that reflected light obtained by irradiating the observation target with light from the light source unit is incident on the spectroscopic sensor. it can.

  In the aspect of the invention, the plurality of photosensor units may be arranged around the light source unit in a plan view with respect to a facing surface facing the observation target.

  As described above, by arranging the plurality of photosensor units around the light source unit, reflected light obtained by irradiating the observation target with the light from the light source unit can be incident on the spectroscopic sensor.

  In the aspect of the invention, the light source unit may be disposed around the plurality of photosensor units in a plan view with respect to the facing surface facing the observation target.

  In one embodiment of the present invention, a plurality of light sources may be included, and the plurality of light sources may be disposed around the plurality of photosensor units in a plan view with respect to a facing surface facing the observation target.

  As described above, the light source unit is arranged around the plurality of photosensor units, so that the reflected light obtained by irradiating the observation target with the light from the light source unit can be incident on the spectroscopic sensor.

  In one embodiment of the present invention, an angle limiting filter for limiting an incident angle of incident light with respect to light receiving regions of the plurality of photosensor units may be included.

  In this way, by limiting the incident angle of the incident light with respect to the light receiving regions of the plurality of photosensor units, it is possible to limit the transmission wavelength bands of the plurality of optical bandpass filters. In addition, light incident on the spectroscopic sensor from the light source unit can be blocked without going through the observation target.

  In the aspect of the invention, the angle limiting filter may be formed of a light shielding material formed by a semiconductor process on the impurity regions for the plurality of photosensor portions.

  In this way, the light shielding material can be formed by a semiconductor process on the impurity regions for the plurality of photosensor portions.

  In the aspect of the invention, the angle limiting filter may be formed by a wiring layer forming step of another circuit formed on the semiconductor substrate.

  In this way, the angle limiting filter can be formed by the wiring layer forming process of another circuit formed on the semiconductor substrate.

  In the aspect of the invention, the angle limiting filter may be formed by a conductive plug of a contact hole formed in an insulating film stacked on the semiconductor substrate.

  In this case, the angle limiting filter can be formed by the conductive plug of the contact hole opened in the insulating film laminated on the semiconductor substrate.

  In the aspect of the invention, the light blocking material forming the angle limiting filter may be a light absorbing material or a light reflecting material.

  In this way, the light shielding material forming the angle limiting filter can be formed of a light absorbing material or a light reflecting material.

  In the aspect of the invention, the angle limiting filter may include the plurality of angle limiting filters from the back side of the semiconductor substrate when a surface on which the impurity regions for the plurality of photosensor parts are formed is the surface of the semiconductor substrate. The light-receiving hole may be formed in the impurity region for the photosensor portion to form the remaining semiconductor substrate.

  In this case, the angle limiting filter can be formed by the remaining semiconductor substrate by forming the light receiving holes in the impurity regions for the plurality of photosensor parts from the back surface side of the semiconductor substrate.

  In the aspect of the invention, the plurality of optical bandpass filters may be formed of a multilayer thin film that is inclined with respect to the semiconductor substrate at an angle corresponding to a transmission wavelength.

  In this way, a plurality of optical bandpass filters can be formed by the multilayer thin film inclined at an angle corresponding to the transmission wavelength with respect to the semiconductor substrate.

  Further, according to one aspect of the present invention, it includes an inclined structure provided on the angle limiting filter, and the inclined structure corresponds to a transmission wavelength of the plurality of optical bandpass filters with respect to the semiconductor substrate. The multilayer thin film may be formed on the inclined surface.

  In this way, the multilayer thin film that is inclined at an angle corresponding to the transmission wavelength can be formed by forming the multilayer thin film on the inclined surface of the inclined structure.

  In one embodiment of the present invention, a light shielding material may be disposed on the back surface of the semiconductor substrate remaining by forming the light receiving hole and the wall surface of the light receiving hole.

  In this way, the light shielding material can be disposed on the back surface of the remaining semiconductor substrate and the side surfaces of the light receiving holes by forming the light receiving holes.

  In one embodiment of the present invention, the light blocking material may be a light absorbing material or a light reflecting material.

  In this way, the light shielding material can be formed of a light absorbing material or a light reflecting material.

  Another aspect of the invention relates to an electronic apparatus including the spectroscopic sensor device described in any of the above.

1A and 1B are configuration examples of the spectroscopic sensor device of the present embodiment. 2A and 2B show a first modification of the spectroscopic sensor device. The 2nd modification of a spectroscopic sensor apparatus. A 3rd modification of a spectroscopic sensor apparatus. The 4th modification of a spectroscopic sensor apparatus. The 1st detailed structural example of a spectroscopic sensor. The 1st detailed structural example of a spectroscopic sensor. The 1st modification of a spectroscopic sensor. The 2nd modification of a spectroscopic sensor. 3rd modification of a spectroscopic sensor. The 4th modification of a spectroscopic sensor. FIGS. 12A and 12B are explanatory diagrams of the transmission wavelength band of the optical bandpass filter. The 1st example of a manufacturing method of a spectroscopic sensor. The 1st example of a manufacturing method of a spectroscopic sensor. The 1st example of a manufacturing method of a spectroscopic sensor. 16A and 16B show a second detailed configuration example of the spectroscopic sensor. The 2nd detailed structural example of a spectroscopic sensor. The 2nd example of a manufacturing method of a spectroscopic sensor. The 2nd example of a manufacturing method of a spectroscopic sensor. The 2nd example of a manufacturing method of a spectroscopic sensor. Configuration example of an electronic device.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as means for solving the present invention. Not necessarily.

1. Configuration Example As described above, there is a demand for a small-sized spectroscopic sensor device that can be always worn in the fields of medical care and health, and there is a problem that the spectroscopic sensor device needs to be downsized. In this embodiment, the spectroscopic sensor device is reduced in size by measuring a specific wavelength band using an optical bandpass filter.

  FIG. 1A and FIG. 1B show a configuration example of the spectroscopic sensor device of the present embodiment. The spectroscopic sensor device of this embodiment includes a spectroscopic sensor 100, a light source 110, a light shielding member 120, a display panel 130 (display device), and an operation input unit 140. In the following, for the sake of simplicity, the configuration of the spectroscopic sensor device is schematically illustrated, and the dimensions and ratios in the drawing are different from the actual ones.

  FIG. 1A is a plan view of a facing surface that faces an observation target. As shown in FIG. 1A, the light source 110 and the spectroscopic sensor 100 are each surrounded by a light shielding member 120. The light blocking member 120 blocks direct light from the light source 110 to the spectroscopic sensor 100, and blocks external light such as sunlight and illumination light. The light shielding member 120 is made of, for example, plastic or metal, and is formed of an opaque material that does not transmit the measurement target wavelength of the spectroscopic sensor 100.

  The light source 110 is composed of, for example, an LED, and irradiates the observation target with light in a wide wavelength band. The light in the wide wavelength band is, for example, white light, and is light in a wide band (for example, several hundred nm) including a measurement wavelength in a narrow band (for example, several tens of nm) of the spectroscopic sensor 100. As will be described later, the light source 110 may be composed of a plurality of light sources, and each of the light sources may irradiate light having different measurement wavelengths.

  The spectroscopic sensor 100 is configured on, for example, a one-chip semiconductor substrate, and spectroscopically measures (detects) light in a specific wavelength band. Specifically, the spectroscopic sensor 100 includes a semiconductor substrate 10, a circuit 20, first to fourth photodiodes 31 to 34 (a plurality of photosensor units in a broad sense), and first to fourth optical bandpass filters 61. To 64 (first to fourth multilayer thin film filters).

  The photodiodes 31 to 34 are elements that are formed on the semiconductor substrate 10 and photoelectrically convert incident light. The photodiodes 31 to 34 receive the incident light transmitted through the optical bandpass filters 61 to 64, respectively.

  The optical bandpass filters 61 to 64 are optical filters that are realized by, for example, a multilayer thin film formed on the photodiodes 31 to 34 and transmit light in a specific wavelength band. The specific wavelength band is a plurality of bands to be measured, and each optical bandpass filter transmits light of each band to be measured. For example, each band to be measured is a band of several tens of nm including the measurement wavelength.

  FIG. 1B is a cross-sectional view taken along line AA of the spectroscopic sensor device shown in FIG. As shown in FIG. 1B, when the spectroscopic sensor device is used, the end surface (opposing surface) of the light shielding member 120 is in contact with the observation target. Both the light source 110 and the spectroscopic sensor 100 are provided so as to face the observation target. Then, light from the light source 110 is irradiated onto the observation target, and reflected light or scattered light from the observation target enters the spectroscopic sensor 100.

  As shown in B <b> 1, the light shielding member 120 includes a member provided between the light source 110 and the spectroscopic sensor 100. This member has, for example, a plate shape, and is provided so as to intersect a straight line connecting the light source and the spectroscopic sensor 100 (light receiving surface of the photodiode). Then, the direct light from the light source 110 to the spectroscopic sensor 100 is shielded by one side of the member being in contact with the observation target in use.

  Note that the spectroscopic sensor device of the present embodiment is not limited to the configuration shown in FIGS. 1A and 1B, and some of the components (for example, the display panel 130 and the input unit 140) may be omitted or others may be omitted. Various modifications such as adding the above-described components (for example, an input / output interface) are possible.

  As described above, the spectroscopic sensor device has a problem that downsizing of the device is required. For example, in a spectroscopic sensor that acquires a continuous spectrum, there is a problem that the apparatus becomes large due to the installation of a prism or the like and securing of the optical path length.

  In this regard, according to the present embodiment, the spectroscopic sensor device irradiates the observation target with the light source unit 110 that irradiates light in a wavelength band including a plurality of wavelengths to be detected, and the light from the light source unit 110. The spectroscopic sensor 100 into which the obtained light is incident is included. The spectroscopic sensor 100 includes a plurality of optical bandpass filters 61 to 64 having different transmission wavelengths and a plurality of photosensor units 31 to 34. For example, the first optical bandpass filter 61 has a wavelength characteristic that transmits the first specific wavelength, and the first photosensor 31 transmits the first specific wavelength that has passed through the first optical bandpass filter 61. Sensing light. The second optical bandpass filter 62 has a wavelength characteristic that transmits a second specific wavelength different from the first specific wavelength, and the second photosensor 32 transmits the second optical bandpass filter 62. The second specific wavelength light is sensed.

  As a result, the spectral sensor device can be reduced in size. That is, by spectroscopically measuring only a specific wavelength using the optical bandpass filters 61 to 64, it is not necessary to install a prism or the like and to ensure the optical path length, and the apparatus can be downsized. In general, in a spectroscopic sensor device used for a specific application, a wavelength to be measured is known, and acquisition of a continuous spectrum as in an analysis application is not essential. Therefore, it is possible to measure only a specific wavelength by the above-described method and to reduce the size of the apparatus.

  Here, the observation target is an object of spectroscopic measurement by the spectroscopic sensor device, and for example, human skin, subcutaneous tissue, blood, liquid such as seawater, agricultural products such as fruits, soil, and the like are assumed.

  Note that the light obtained by irradiating the observation target with light from the light source unit 110 may be reflected light or scattered light from the observation target as described above. As will be described later with reference to FIG. May be transmitted light that has passed through.

  Further, in this embodiment, when reflected light obtained by irradiating the observation target with light from the light source unit 110 enters the spectroscopic sensor 100, the light source unit 110 enters the spectroscopic sensor 100 without passing through the observation target. A light shielding member 120 that shields light to be transmitted.

  More specifically, the light source unit 110 emits illumination light so as to cross a facing surface facing the observation target, and the spectroscopic sensor 100 reflects reflected light or scattered light from the observation target incident across the facing surface. Receive light. The light shielding member 120 is provided between the light source unit 110 and the spectroscopic sensor 100.

  For example, as described above with reference to FIG. 1B, the light source unit 110 and the spectroscopic sensor 100 are installed next to each other, and a light shielding member (part shown in B1) so as to block direct light from the light source 110 to the spectroscopic sensor 100. Is provided. Alternatively, as will be described later with reference to FIG. 2, the spectroscopic sensor 100 may be installed around the light source unit 110, and the light shielding member 121 may be provided so as to surround the light source 110.

  In this way, light incident on the spectroscopic sensor 100 from the light source unit 110 without passing through the observation target can be shielded, and only reflected light or scattered light from the observation target can be split. Thereby, S / N deterioration by direct light can be suppressed.

  Here, the above-described facing surface is a surface that is assumed to face the observation target when the spectroscopic sensor device is used. For example, as shown in FIG. 1B, when the end face of the light shielding member 120 is formed so as to be in contact with the observation target, the plane including the end face is the facing face.

  In the present embodiment, the plurality of photosensor units 31 to 34 of the spectroscopic sensor 100 are arranged in an array on the first direction side of the light source unit 110 in a plan view with respect to the facing surface facing the observation target. For example, in FIG. 1A, the first direction is the direction indicated by D1, and the plurality of photosensor units 31 to 34 are arranged not on the periphery of the light source unit 110 but on a specific direction D1 side.

  In addition, as will be described later with reference to FIG. 2, the plurality of photosensor units 31 to 34 may be disposed around the light source unit 110 in a plan view with respect to the facing surface facing the observation target.

  Further, as will be described later with reference to FIGS. 3 and 4, the light source unit 110 may be disposed around the plurality of photosensor units 31 to 34 in a plan view with respect to the facing surface facing the observation target. For example, as illustrated in FIG. 3, the light source unit 110 may include a plurality of light sources 111 to 114, and the plurality of light sources 111 to 114 may be disposed around the plurality of photosensor units 31 to 34. Or as shown in FIG. 4, the light source part 110 may be comprised by one light source, and the one light source may be arrange | positioned so that the several photosensor parts 31-34 may be enclosed.

  According to these embodiments, the light source unit 110 and the spectroscopic sensor 100 can be arranged in a compact manner, and the spectroscopic sensor device can be downsized. Further, when the light source unit 110 is arranged around the plurality of photosensor units 31 to 34, the spectroscopic sensor 100 can be further away from the external light, so that S / N deterioration due to the external light can be suppressed.

2. Modified Examples As mentioned above, the spectral sensor device of the present embodiment can have various modified configurations. Various modified examples of the spectroscopic sensor device will be described with reference to FIGS.

  2A and 2B show a first modification of the spectroscopic sensor device in which a photodiode is arranged around the light source unit. The spectroscopic sensor device includes a spectroscopic sensor 100, a light source unit 110, and light shielding members 121 and 122.

  FIG. 2A is a plan view of a facing surface facing the observation target. As shown in FIG. 2A, a light shielding member 121 is installed so as to surround the light source unit 110, and a plurality of photodiodes 31 to 34 are arranged outside the light shielding member 121. For example, the photodiodes 31 to 34 are disposed on the first to fourth directions D1 to D4 side of the light source unit 110. Here, in a plan view with respect to the facing surface, D2 is a direction orthogonal to D1, D3 is a direction opposite to D1, and D4 is a direction opposite to D2. A light shielding member 122 for shielding external light is installed around the photodiodes 31 to 34.

  FIG. 2B is a CC cross-sectional view of the spectroscopic sensor device shown in FIG. As shown in FIG. 2B, the light source unit 110 and the light shielding member 121 are installed (stacked) on the semiconductor substrate 10 on which the photodiodes 31 to 34 are formed. In the region on the semiconductor substrate 10 where the light source unit 110 is installed, for example, a driver circuit for the light source 110 and a detection circuit for the photodiodes 31 to 34 are formed. Here, “on the semiconductor substrate 10” is a direction perpendicular to the plane of the semiconductor substrate 10 and is a direction on the side where the photodiodes 31 to 34, the optical bandpass filters 61 to 64, and the like are formed.

  FIG. 3 shows a second modification of the spectroscopic sensor device in which a plurality of light sources are arranged around the spectroscopic sensor 100. The spectroscopic sensor device includes a spectroscopic sensor 100, first to fourth light sources 111 to 114 (a plurality of light sources in a broad sense), and a light shielding member 120.

  As shown in FIG. 3, a light shielding member 120 is installed so as to surround the spectroscopic sensor 100, and light sources 111 to 114 are arranged outside the light shielding member 120. For example, the light sources 111 to 114 are arranged on the first to fourth directions D1 to D4 side of the spectroscopic sensor 100. For example, when the transmission wavelengths of the optical bandpass filters 61 to 64 are included in the visible light, the light sources 111 to 114 irradiate the observation target with white light. Alternatively, the light sources 111 to 114 may irradiate light in different wavelength bands corresponding to the transmission wavelengths of the optical bandpass filters 61 to 64, respectively.

  FIG. 4 shows a third modification of the spectroscopic sensor device in which one light source surrounds the spectroscopic sensor 100. The spectroscopic sensor device includes a spectroscopic sensor 100, a light source unit 110, and a light shielding member 120.

  As shown in FIG. 4, a light shielding member 120 is installed so as to surround the spectroscopic sensor 100, and a continuous light source 110 such as a rectangle or a circle surrounding the outside of the light shielding member 120 is arranged. The light source 110 is realized by, for example, EL (Electro-Luminescence) that emits white light, and is formed on the EL substrate 150. For example, the spectroscopic sensor 100 is stacked on the EL substrate.

  FIG. 5 shows a fourth modification of the spectroscopic sensor device that spectroscopically measures the transmitted light to be observed. The spectroscopic sensor device includes a spectroscopic sensor 100, a light source unit 110, a light shielding member 120, a display panel 130, and an operation input unit 140.

  As shown in FIG. 5, the light source unit 110 and the spectroscopic sensor 100 are installed to face each other with an observation target in between when the spectroscopic sensor device is used. That is, the light source unit 110 irradiates the observation target with illumination light, the illumination light transmitted through the observation target enters the spectroscopic sensor 100, the optical bandpass filters 61 and 63 split the transmitted light, and a photodiode (illustrated). (Omitted) senses the transmitted light after spectroscopy.

3. First Detailed Configuration Example of Spectroscopic Sensor As described above, the spectroscopic sensor device can be downsized by using a spectroscopic sensor that measures only a specific measurement wavelength instead of a continuous spectrum. However, there is a problem that the size of the spectroscopic sensor device is limited by the size of the spectroscopic sensor itself.

  However, there is a problem of improving the wavelength selectivity of the spectroscopic sensor. For example, as will be described later, the spectral sensor of the present embodiment is provided with an angle limiting filter for limiting the transmission wavelength band of the optical bandpass filter. At this time, if the angle limiting filter or the optical bandpass filter is formed of a member, light is diffused and attenuated on the bonding surface of the member, so that the wavelength selectivity is lowered.

  For example, Patent Document 1 described above discloses a technique for limiting the transmission wavelength band of a filter by limiting the incident angle of incident light using an optical fiber. However, in this method, if the numerical aperture of the optical fiber is reduced in order to narrow the band, the transmittance of incident light is lowered and the wavelength selectivity is lowered.

  There is also a problem of simplifying the manufacturing process of the spectroscopic sensor. For example, Patent Document 2 discloses a technique using a multilayer filter having a different film thickness for each sensor. However, this method requires a separate multilayer film forming process for each film thickness, and thus the multilayer film forming process becomes complicated.

  Therefore, in this embodiment, the angle limiting filter and the optical bandpass filter are formed by a semiconductor process, so that the spectral sensor can be downsized by a simple manufacturing process.

  A first detailed configuration example of the spectroscopic sensor will be described with reference to FIGS. In the following, for the sake of simplicity, the configuration of the spectroscopic sensor is schematically illustrated, and the dimensions and ratios in the drawing are different from actual ones.

  FIG. 6 shows a plan view of the semiconductor substrate 10 on which the spectroscopic sensor is formed. FIG. 6 is a plan view seen from the surface side where the circuit 20 and the angle limiting filter 41 are formed in a plan view seen from a direction perpendicular to the plane of the semiconductor substrate 10. As will be described later, a multilayer filter is formed on the angle limiting filters 41 and 42, but the illustration is omitted in FIG. 6 for simplicity.

  The spectroscopic sensor shown in FIG. 6 includes a semiconductor substrate 10, a circuit 20, a first photodiode 31 (in a broad sense, a first photosensor, an impurity region for the first photodiode), a second photodiode 32 ( In a broad sense, it includes a second photosensor, an impurity region for the second photodiode, a first angle limiting filter 41, and a second angle limiting filter.

  The semiconductor substrate 10 is composed of, for example, a P-type or N-type silicon substrate (silicon wafer). On the semiconductor substrate 10, a circuit 20, photodiodes 31, 32, and angle limiting filters 41, 42 are formed by a semiconductor process. Here, the top of the semiconductor substrate 10 represents the direction on the side where the circuit 20, the angle limiting filter 41, etc. are formed, among the directions perpendicular to the plane of the semiconductor substrate 10.

  The angle limiting filters 41 and 42 are formed, for example, in a lattice shape in a plan view, and limit the incident angle of incident light with respect to the photodiodes 31 and 32. The circuit 20 includes an amplifier that processes output signals from the photodiodes 31 and 32, an A / D conversion circuit, and the like, for example.

  Note that the spectroscopic sensor of the present embodiment is not limited to the configuration shown in FIG. 6, and various modifications such as omitting some of the components (circuit 20) or adding other components are possible. It is. For example, the number of photodiodes and angle limiting filters may be two as described above, or one or more may be formed. Further, the angle limiting filters 41 and 42 may have a lattice shape in a plan view as described above, or may have another shape.

  FIG. 7 shows a cross-sectional view of the spectroscopic sensor. FIG. 7 is a cross-sectional view taken along the DD cross section shown in FIG. The spectroscopic sensor shown in FIG. 7 includes a semiconductor substrate 10, photodiodes 31, 32, angle limiting filters 41, 42, an inclined structure 50 (angle structure), a first optical bandpass filter 61 (first multilayer filter). , First dielectric filter) and second optical bandpass filter 62 (second multilayer filter, second dielectric filter).

  As shown in FIG. 7, photodiodes 31 and 32 are formed on the semiconductor substrate 10. As will be described later, the photodiodes 31 and 32 are formed by forming impurity regions by ion implantation or the like. For example, the photodiodes 31 and 32 are realized by a PN junction between an N-type impurity region formed on the P substrate and the P substrate. Alternatively, it is realized by a PN junction between a P-type impurity region formed on a deep N well (N-type impurity region) and the deep N well.

The angle limiting filters 41 and 42 are formed of a light shielding material (light absorbing material or light reflecting material) having a light shielding property with respect to the wavelength detected by the photodiodes 31 and 32. Specifically, the angle limiting filters 41 and 42 are formed by a wiring formation process of a semiconductor process, and include, for example, a conductive layer such as an aluminum (light reflecting material) wiring layer and a conductive plug such as a tungsten (light absorbing material) plug. It is formed. The aspect ratios of the length (for example, the longest diagonal line of the bottom surface and the long diameter) and the height of the angle limiting filters 41 and 42 and the height aspect ratio will be described later with reference to the transmission wavelength band of the optical bandpass filters 61 and 62 (for example, FIG. 12B). BW1, BW2). The openings (hollow portions) of the angle limiting filters 41 and 42 are formed of a material transparent to the wavelength detected by the photodiodes 31 and 32, and are formed of an insulating layer such as SiO ₂ (silicon oxide film). (Filled).

The inclined structure 50 is formed on the angle limiting filters 41 and 42 and has inclined surfaces having different inclination angles depending on the transmission wavelengths of the optical bandpass filters 61 and 62. Specifically, a plurality of inclined surfaces with an inclination angle θ1 with respect to the plane of the semiconductor substrate 10 are formed on the photodiode 31, and a plurality of inclined surfaces with an inclination angle θ2 different from θ1 are formed on the photodiode 32. It is formed. As will be described later, the inclined structure 50 is formed by processing an insulating film such as SiO ₂ by etching or CMP, a gray scale lithography technique, or the like.

  The optical bandpass filters 61 and 62 are formed by the multilayer thin film 60 laminated on the inclined structure 50. The transmission wavelength bands of the optical bandpass filters 61 and 62 are determined by the inclination angles θ1 and θ2 of the inclined structure 50 and the incident light limiting angle (aspect ratio) of the angle limiting filters 41 and 42. Since the optical bandpass filters 61 and 62 have different transmission wavelengths depending on the tilt angle, they are not laminated in separate processes for each transmission wavelength, but are laminated in the same multilayer film forming process.

  As described above, there is a problem that it is necessary to reduce the size of the spectroscopic sensor in order to reduce the size of the spectroscopic sensor device. Further, there are problems of improving the wavelength selectivity of the spectroscopic sensor and simplifying the manufacturing process.

  In this regard, according to the present embodiment, the spectroscopic sensor includes the angle limiting filters 41 and 42 for limiting the incident angle of the incident light with respect to the light receiving region (light receiving surface) of the photodiode. The angle limiting filters 41 and 42 are formed of a light shielding material (for example, a light absorbing material or a light reflecting material) formed by a semiconductor process on the impurity regions 31 and 32 for the photodiode.

  Thereby, since each component of the spectroscopic sensor can be configured by a semiconductor process, the spectroscopic sensor can be downsized. That is, by forming the photodiodes 31 and 32 and the angle limiting filters 41 and 42 by a semiconductor process, it is possible to easily perform microfabrication and reduce the size. Further, the manufacturing process can be simplified as compared with the case where the members are bonded to each other. Moreover, compared with the case where an optical fiber is used as the angle limiting filter, it is possible to suppress a decrease in transmitted light due to a decrease in the limiting angle (numerical aperture). In addition, a decrease in transmitted light due to adhesion of members can be suppressed. Therefore, it becomes easy to secure the light amount, and the transmission angle band can be further reduced by reducing the limit angle.

  Here, the semiconductor process is a process for forming a transistor, a resistance element, a capacitor, an insulating layer, a wiring layer, or the like on a semiconductor substrate. For example, the semiconductor process is a process including an impurity introduction process, a thin film formation process, a photolithography process, an etching process, a planarization process, and a heat treatment process.

  The light receiving region of the photodiode is a region on the impurity regions 31 and 32 for the photodiode where the incident light that has passed through the angle limiting filters 41 and 42 is incident. For example, in FIG. 6, it is a region corresponding to each opening of the grid-shaped angle limiting filters 41 and 42. Alternatively, in FIG. 7, a region (for example, region LRA) surrounded by a light shielding material (for example, a light absorbing material or a light reflecting material) forming the angle limiting filters 41 and 42.

In the present embodiment, the angle limiting filters 41 and 42 are formed by a wiring layer forming process of another circuit 20 formed on the semiconductor substrate 10. Specifically, the angle limiting filters 41 and 42 are formed simultaneously with the formation of the wiring layer of the circuit 20, and are formed by all or part of the wiring layer forming process. For example, the angle limiting filters 41 and 42 are formed by forming an aluminum (light reflecting material in a broad sense) wiring layer by aluminum sputtering, forming an insulating film by SiO ₂ deposition, or forming a contact by tungsten (light absorbing material in a broad sense) deposition. Etc. are formed.

  In this way, the angle limiting filters 41 and 42 can be formed on the photodiode impurity regions 31 and 32 by a semiconductor process. Accordingly, it is not necessary to provide a separate process for forming the angle limiting filter, and the angle limiting filter can be formed using a normal semiconductor process.

  The angle limiting filters 41 and 42 are not limited to an aluminum (light reflecting material) wiring layer and a tungsten (light absorbing material) contact, but are a wiring layer made of a light absorbing material such as tungsten and a contact made of a light reflecting material such as aluminum. May be formed. However, the light shielding property increases as the light absorbing material is formed.

  In addition, the angle limiting filters 41 and 42 are not limited to the aluminum (light reflecting material) wiring layer and the tungsten (light absorbing material) contact, but the aluminum (light reflecting material) with a film such as titanium nitride (TiN) which is a light absorbing material. ) A wiring layer or a tungsten (light absorbing material) contact may be formed. The aluminum (light reflecting material) wiring layer is changed to light absorption, and titanium nitride (TiN) has higher light absorption than tungsten, so that the light absorption of the contact also increases, so that the light shielding property can be further improved.

  In the present embodiment, the angle limiting filters 41 and 42 may be formed by conductive plugs of contact holes opened in an insulating film stacked on the semiconductor substrate 10. That is, a metal wiring layer such as an aluminum (light reflecting material) wiring may not be used, but only a conductive plug such as a tungsten (light absorbing material) plug formed in an insulating film such as SiO 2. Note that the angle limiting filters 41 and 42 are not limited to tungsten plugs, and may be formed of other conductive plugs such as aluminum and polysilicon.

  In this way, the angle limiting filters 41 and 42 can be formed of conductive plugs.

  Here, the contact hole is a contact hole that is opened for a contact that connects the wiring layer and the semiconductor substrate, or a contact hole that is opened for a via contact that connects the wiring layer and the wiring layer.

  In the present embodiment, the angle limiting filters 41 and 42 are electrodes that are formed by a conductive layer or a conductive plug formed by a semiconductor process and obtain signals from the impurity regions for the photodiodes 31 and 32. Also good. For example, when the impurity regions for the photodiodes 31 and 32 are P-type impurity regions, the angle limiting filters 41 and 42 that conduct to the P-type impurity regions may also serve as the anode electrodes of the photodiodes 31 and 32.

  In this way, the angle limiting filters 41 and 42 formed by the conductive layer or the conductive plug can be used as the electrodes of the photodiodes 31 and 32. Thereby, it is not necessary to provide an electrode other than the angle limiting filters 41 and 42, and a decrease in the amount of incident light due to the electrode can be avoided.

  In the present embodiment, the angle limiting filters 41 and 42 are formed along the outer periphery of the light receiving region of the photodiodes 31 and 32 in a plan view with respect to the semiconductor substrate 10. Specifically, each of the impurity regions for the photodiodes 31 and 32 is one light receiving region, and one angle limiting filter is formed so as to surround the outer periphery of the impurity region. Alternatively, a plurality of light receiving regions may be set in the impurity regions for the photodiodes 31 and 32, and a plurality of openings may be formed along the outer periphery of the plurality of light receiving regions. For example, as shown in FIG. 6, square light shielding materials surround each light receiving region in plan view, and the angle limiting filters 41 and 42 are formed by arranging the squares in a lattice shape.

  In addition, the angle limiting filters 41 and 42 are not limited to being closed along the outer periphery of the light receiving region, but may have discontinuous portions along the outer periphery or may be intermittently disposed along the outer periphery. Also good.

  In this way, the angle limiting filters 41 and 42 are formed along the outer periphery of each light receiving region of the photodiodes 31 and 32, so that the incident angle of the incident light with respect to each light receiving region of the photodiodes 31 and 32 can be reduced. Can be limited.

  In the present embodiment, the optical bandpass filters 61 and 62 are formed of multilayer thin films that are inclined with respect to the semiconductor substrate 10 at angles θ1 and θ2 according to the transmission wavelength. More specifically, the optical bandpass filters 61 and 62 are formed of a plurality of sets of multilayer thin films having different transmission wavelengths. The plurality of sets of multilayer thin films are formed in the same thin film forming process because the inclination angles θ1 and θ2 with respect to the semiconductor substrate 10 differ according to the transmission wavelength. For example, as shown in FIG. 7, a set of multilayer thin films is formed by continuously arranging a plurality of multilayer thin films having an inclination angle θ1. Alternatively, as will be described later with reference to FIG. 10, when the multilayer thin films having different inclination angles θ1 to θ3 are arranged adjacent to each other, and the multilayer thin films having the inclination angles θ1 to θ3 are repeatedly arranged, the same inclination angle (for example, θ1). A plurality of multilayer thin films may form a set of multilayer thin films.

  In this way, the optical bandpass filters 61 and 62 can be formed by the multilayer thin film inclined at the angles θ1 and θ2 corresponding to the transmission wavelength. This eliminates the need for laminating a multilayer thin film having a film thickness corresponding to the transmission wavelength in a separate process for each transmission wavelength, thereby simplifying the multilayer thin film formation process.

  Here, the simultaneous thin film forming process is not a process of sequentially repeating the same process of forming the second set of multilayer thin films after forming the first set of multilayer thin films, but the plurality of sets of multilayer thin films are the same (simultaneously, It means forming in a thin film forming step.

  In the present embodiment, the spectroscopic sensor includes an inclined structure 50 provided on the angle limiting filters 41 and 42. The inclined structure 50 has an inclined surface inclined at angles θ1 and θ2 corresponding to the transmission wavelengths of the optical bandpass filters 61 and 62 with respect to the semiconductor substrate 10, and the multilayer thin film is on the inclined surface. It is formed.

  In this way, by forming a multilayer thin film on the inclined surface of the inclined structure 50, it is possible to form a multilayer thin film inclined at angles θ1 and θ2 corresponding to the transmission wavelengths of the optical bandpass filters 61 and 62.

  Specifically, in the present embodiment, the inclined structure 50 is formed on the angle limiting filters 41 and 42 by a semiconductor process. For example, as will be described later with reference to FIG. 14 and the like, in the inclined structure 50, a step or a dense pattern is formed in a transparent film (insulating film) laminated by a semiconductor process, and the step or the dense pattern is polished (for example, CMP). And at least one of etching is performed.

  In this way, the inclined structure can be formed by a semiconductor process. Thereby, the formation process of an inclination structure can be simplified. Moreover, cost can be reduced compared with the case where an inclination structure is comprised by another member. Moreover, the light quantity reduction | decrease in an adhesion surface with the inclination structure of another member can be avoided.

  Here, the level difference of the insulating film is, for example, a difference in height of the surface of the insulating film from the surface of the semiconductor substrate in the cross section of the semiconductor substrate. In addition, the insulating film density pattern is, for example, a height pattern on the surface of the insulating film from the surface of the semiconductor substrate in the cross section of the semiconductor substrate, and the density of the insulating film is formed by the ratio of the high part to the low part.

  Note that the inclined structure 50 is not limited to being formed by polishing or etching a step or a dense pattern, but may be formed by a gray scale lithography technique. In the gray scale lithography technique, a resist is exposed using a gray scale mask having light and shade, and etched using the exposed resist to form an inclined structure.

4). In the above embodiment, the configuration example in which the inclined structure 50 is formed by a semiconductor process has been described. However, in this embodiment, various modifications can be made.

  FIG. 8 shows a first modification of the spectroscopic sensor in which the inclined structure 50 is formed by another member and bonded. The spectroscopic sensor shown in FIG. 8 includes a semiconductor substrate 10, photodiodes 31 and 32, angle limiting filters 41 and 42, an inclined structure 50, optical bandpass filters 61 and 62, an insulating layer 70, and an adhesive layer 80. In the following, the components described above with reference to FIG.

  In the first modification, the angle limiting filters 41 and 42 are formed by a semiconductor process in the same manner as the above-described configuration example. An insulating layer 70 (or a passivation layer) is stacked on the angle limiting filters 41 and 42. The insulating layer 70 is not necessarily an insulating film, and may be a transparent film that transmits a wavelength to be sensed. The inclined structure 50 is formed by heat-pressing another member such as a low-melting glass with a mold, and an inclined surface and a multilayer thin film are formed. The inclined structure 50 and the insulating layer 70 are pasted with a transparent adhesive that transmits the sensing wavelength.

  FIG. 9 shows a second modification of the spectroscopic sensor that forms a multilayer thin film parallel to the semiconductor substrate 10 without using the inclined structure 50. The spectroscopic sensor shown in FIG. 9 includes a semiconductor substrate 10, photodiodes 31 and 32, angle limiting filters 41 and 42, optical bandpass filters 61 and 62, and an insulating layer 70.

  In the second modification, the angle limiting filters 41 and 42 are formed by a semiconductor process in the same manner as the above-described configuration example, and the insulating layer 70 is laminated on the angle limiting filters 41 and 42. Then, a multilayer thin film of optical bandpass filters 61 and 62 is formed on the insulating layer 70. The multilayer thin film has a different film thickness depending on the transmission wavelength of the optical bandpass filters 61 and 62, and is laminated by separate forming steps. That is, when one of the optical bandpass filters 61 and 62 is formed, the other is covered with a photoresist or the like, and a multilayer film is laminated to form multilayer thin films having different thicknesses.

  FIG. 10 shows a third modification of the spectroscopic sensor in which the impurity region for the photodiode is divided by a trench. The spectroscopic sensor shown in FIG. 10 includes a semiconductor substrate 10, photodiodes 31 and 32, angle limiting filters 41 and 42, an inclined structure 50, optical bandpass filters 61 to 63, and an insulating layer 70. Since the photodiode 32 is the same as the photodiode 31, illustration and description thereof are omitted.

  In the third modification, the impurity region of the photodiode 31 is divided by the trench 90, and the photodiodes 31-1 to 31-3 are formed. The trench 90 is formed by an insulator trench structure such as STI (Shallow Trench Isolation). The inclined structure 50 is formed with inclined surfaces having inclination angles θ1 to θ3, and the inclined surfaces correspond to the photodiodes 31-1 to 31-3, respectively. Then, optical bandpass filters 61 to 63 having different inclination angles are formed on the photodiodes 31-1 to 31-3, respectively.

  In FIG. 10, one optical bandpass filter is provided on one photodiode (one region) partitioned by a trench structure. However, in this embodiment, one optical bandpass filter has a trench structure. It may be provided on a plurality of photodiodes (a plurality of regions) separated by.

  FIG. 11 shows a fourth modification of the spectroscopic sensor that increases the amount of incident light by a micro-lens array (MLA). The spectroscopic sensor shown in FIG. 11 includes a semiconductor substrate 10, photodiodes 31 and 32, angle limiting filters 41 and 42, an inclined structure 50, optical bandpass filters 61 and 62, an insulating layer 70, and a microlens array 95. Since the photodiode 32 is the same as the photodiode 31, illustration and description thereof are omitted.

In the fourth modification, a microlens is formed in each opening of the angle limiting filter 41, and a microlens array 95 is configured by the plurality of microlenses. The microlens array 95 is formed, for example, by forming a pattern by photolithography after forming the angle limiting filter 41, etching the SiO ₂ film, and depositing a material having a higher refractive index than SiO ₂ .

5. As described above, the transmission wavelength band of the optical bandpass filter is set by the tilt angle of the multilayer thin film and the limiting angle of the angle limiting filter. This point will be specifically described with reference to FIGS. 12A and 12B. In order to simplify the description, a case where the film thicknesses of the multilayer thin films 61 and 62 are the same will be described below as an example. However, in this embodiment, the film thicknesses of the multilayer thin films 61 and 62 are set to the inclination angles θ1 and θ2. It may be different depending on the situation. For example, when the thin film is grown in the direction perpendicular to the semiconductor substrate in the thin film deposition, the film thicknesses of the multilayer thin films 61 and 62 may be proportional to cos θ1 and cos θ2.

  As shown in FIG. 12A, the multilayer thin films 61 and 62 are formed of thin films having thicknesses d1 to d3 (d2 <d1, d3 <d1). A plurality of thin films having thicknesses d2 and d3 are alternately stacked above and below the thin film having thickness d1. The thin film having the thickness d2 is formed of a material having a refractive index different from those of the thin films having the thicknesses d1 and d3. In FIG. 12A, the number of thin films having thicknesses d2 and d3 is omitted for the sake of simplicity, but in reality, several tens to several hundreds of thin films are formed above and below the thin film having thickness d1. Are stacked. In FIG. 12A, for the sake of simplicity, the thin film having the thickness d1 is made one layer, but in reality, a plurality of layers are often formed.

  Since the multilayer thin film 61 has an inclination angle θ1 with respect to the light receiving surface of the photodiode 31, light rays perpendicular to the light receiving surface enter the multilayer thin film 61 at an angle θ1. Then, if the limiting angle of the angle limiting filter 41 is Δθ, light rays incident on the multilayer thin film 61 at θ1−Δθ to θ1 + Δθ reach the light receiving surface of the photodiode 31. Similarly, light incident on the multilayer thin film 62 at θ2−Δθ to θ2 + Δθ reaches the light receiving surface of the photodiode 32.

  As shown in FIG. 12B, the transmission wavelength band BW1 of the multilayer thin film 61 is λ1−Δλ to λ1 + Δλ. At this time, the transmission wavelength λ1 = 2 × n × d1 × cos θ1 with respect to the light beam having the incident angle θ1. Here, n is the refractive index of the thin film having the thickness d1. Further, λ1−Δλ = 2 × n × d1 × cos (θ1 + Δθ) and λ1 + Δλ = 2 × n × d1 × cos (θ1−Δθ). The full width at half maximum HW (for example, HW <BW1) of the transmission wavelength with respect to the light beam having the incident angle θ1 is determined by the number of multilayer films. The amount of light received by the photodiode 31 is maximum at an incident angle θ1 perpendicular to the light receiving surface, and is zero at the limit angle. Therefore, the amount of light received by the entire incident light is represented by a curve indicated by a dotted line. Similarly, the transmission wavelength band BW2 of the multilayer thin film 62 is λ2−Δλ to λ2 + Δλ. For example, if θ2 <θ1, λ2 = 2 × n × d1 × cos θ2 <λ1 = 2 × n × d1 × cos θ1.

  According to the above embodiment, the angle limiting filters 41 and 42 limit the incident angle of incident light to θ1−Δθ to θ1 + Δθ and θ2−Δθ to θ2 + Δθ, and change the transmission wavelength change range from λ1−Δλ to λ1 + Δλ, λ2. It is limited to -Δλ to λ2 + Δλ. In the optical band-pass filter, bands BW1 and BW2 of specific wavelengths to be transmitted are set by the transmission wavelength change ranges λ1−Δλ to λ1 + Δλ and λ2−Δλ to λ2 + Δλ limited by the angle limiting filters 41 and 42.

  In this way, the transmission wavelength bands BW1 and BW2 of the optical bandpass filter are limited by the angle limiting filters 41 and 42, and only the light in the wavelength band to be measured can be sensed. For example, the limiting angle of the angle limiting filters 41 and 42 is set to Δθ ≦ 30 °. Desirably, the limiting angle of the angle limiting filters 41 and 42 is Δθ ≦ 20 °.

  In the above, as shown in FIGS. 1A and 1B, the light shielding member 120 is provided between the light source unit 110 and the spectroscopic sensor 100, and the observation target is not passed from the light source unit 110 to the spectroscopic sensor 100. The case where the incident light is shielded has been described. However, when the observation target is dynamic, a gap is generated between the observation target and the light shielding member 120, and light from the light source unit 110 that does not pass through the observation target may slightly enter the spectroscopic sensor 100. In this case, the incident angle of the light not passing through the observation target is a relatively deep angle (for example, the incident angle> 30 °).

  As described above, the angle limiting filters 41 and 42 limit the incident angle of the spectral filter 100 to 20 ° to 30 ° or less, so that when the observation target is dynamic, the observation target is moved from the light source unit 110 to the spectral filter 100. Light incident without passing through can be eliminated. Further, not only light from the light source unit 110 but also other light (for example, the sun, a fluorescent lamp, etc.) incident from a gap generated between the observation target and the light shielding member 120 when the observation target is dynamic. The same effect is obtained with respect to external light. The angle sensors 41 and 42 also have such additional effects.

6). First Method for Producing Spectroscopic Sensor An example of a method for producing a spectroscopic sensor having the first detailed configuration example will be described with reference to FIGS.

  First, as shown in S1 of FIG. 13, an N-type diffusion layer (an impurity region of a photodiode) is formed on a P-type substrate by photolithography, ion implantation, and photoresist stripping processes. As shown in S2, a P-type diffusion layer is formed on the P-type substrate by photolithography, ion implantation, photoresist stripping, and heat treatment. This N type diffusion layer becomes the cathode of the photodiode, and the P type diffusion layer (P type substrate) becomes the anode.

Next, as shown in S3, a contact is formed. In this formation step, first, an insulating film is formed by a SiO ₂ deposition step and a planarization step by CMP. Then photolithography, anisotropic dry etching of SiO _2, by a process of photoresist stripping, contact holes are formed. Then, the contact hole is filled by TiN sputtering, W (tungsten) deposition, and W etchback. Next, as shown in S4, the first AL wiring is formed by the steps of AL (aluminum) sputtering, TiN sputtering, photolithography, AL and TiN anisotropic dry etching, and photoresist stripping.

Next, as shown in S5, a via contact and a second AL wiring are formed by the same process as S3 and S4. Then, this step S5 is repeated as many times as necessary. FIG. 13 illustrates a case where the third AL wiring is formed. Next, as shown in S6, an insulating film is formed by SiO ₂ deposition (shown by dotted lines) and planarization by CMP. Through the above wiring formation process, the AL wiring and the tungsten plug constituting the angle limiting filter are laminated.

Next, as shown in S7 in FIG. 14, deposition of SiO _2, photolithography, anisotropic dry etching of SiO _2, by a process of photoresist stripping, steps S7 'or sparse and dense pattern of the insulating film (shown by a dotted line) S7 "is formed.

  Next, as shown in S8, an inclined surface of the inclined structure is formed by a polishing process using CMP. At this time, the inclined surface of the inclined structure is processed at an inclination angle corresponding to the step of the insulating film and the shape of the dense pattern.

Next, as shown in S9 of FIG. 15, sputtering of TiO ₂ (titanium oxide film) and sputtering of SiO ₂ are performed alternately to form a multilayer thin film on the inclined surface. The TiO ₂ film is a thin film having a high refractive index, and the SiO ₂ film is a thin film having a lower refractive index than the TiO ₂ film.

7). Second Detailed Configuration Example of Spectroscopic Sensor In the above embodiment, the case where the angle limiting filter is formed by the wiring layer has been described. However, in this embodiment, the angle limiting filter is formed on the back surface of the semiconductor substrate by the silicon trench. Also good.

  A second detailed configuration example of this spectroscopic sensor will be described with reference to FIGS. In the following, for the sake of simplicity, the configuration of the spectroscopic sensor of the present embodiment is schematically illustrated, and the dimensions and ratios in the drawing are different from the actual ones.

  16A and 16B are plan views of the semiconductor substrate 10 on which the spectroscopic sensor is formed. The spectroscopic sensor shown in FIGS. 16A and 16B includes a semiconductor substrate 10, a circuit 20, first and second photodiodes 31 and 32, and first and second angle limiting filters 41 and 42. . As will be described later, a multilayer filter is formed on the angle limiting filters 41 and 42, but the illustration is omitted in FIGS. 16A and 16B for simplicity.

  FIG. 16A is a plan view seen from the surface side where impurity regions, wiring layers, and the like are formed in a plan view seen from a direction perpendicular to the plane of the semiconductor substrate 10. Photodiodes 31 and 32 and a circuit 20 are formed on the surface side of the semiconductor substrate 10 by a semiconductor process.

  FIG. 16B is a plan view seen from the back side in a plan view seen from a direction perpendicular to the plane of the semiconductor substrate 10. On the back surface of the semiconductor substrate 10, angle limiting filters 41 and 42 are formed by silicon trenches toward the photodiodes 31 and 32 formed on the front surface side. The angle limiting filters 41 and 42 are formed, for example, in a lattice shape in a plan view, and limit the incident angle of incident light incident on the photodiodes 31 and 32 from the back side of the semiconductor substrate 10.

  Here, the silicon trench is a technique for excavating the semiconductor substrate 10 by a semiconductor process or MEMS (Micro-Electro-Mechanical System) technology. For example, a method of forming holes, grooves, steps, etc. by dry etching on a silicon substrate.

  Note that the spectroscopic sensor of the present embodiment is not limited to the configuration shown in FIGS. 16A and 16B, and some of the components (circuit 20) may be omitted, or other components may be added. Various modifications such as this are possible.

  FIG. 17 shows a cross-sectional view of the spectroscopic sensor in the EE cross section shown in FIG. The spectroscopic sensor shown in FIG. 17 includes a semiconductor substrate 10, a wiring layer 15, a light shielding material 25, photodiodes 31 and 32, angle limiting filters 41 and 42, an inclined structure 50, first and second optical bandpass filters 61, 62, including an insulating layer 70 (transparent film in a broad sense).

  Here, “up” in the present embodiment is a direction perpendicular to the plane of the semiconductor substrate 10 and a direction away from the semiconductor substrate 10. That is, the direction away from the semiconductor substrate 10 is also on the back side.

  As shown in FIG. 17, photodiodes 31 and 32 are formed on the surface side of the semiconductor substrate 10. The photodiodes 31 and 32 are formed by forming P-type and N-type impurity regions by ion implantation or the like, and are realized by a PN junction of the impurity regions.

  A wiring layer 15 is formed on the photodiodes 31 and 32. The wiring layer 15 is laminated by the formation process of the circuit 20 and the like described above. Output signals from the photodiodes 31 and 32 are input to the above-described circuit 20 and the like through the wiring in the wiring layer 15 and subjected to detection processing.

  Angle limiting filters 41 and 42 are formed on the back side of the semiconductor substrate 10. The angle limiting filters 41 and 42 are formed by the semiconductor substrate 10 left by the silicon trench. A light shielding material (light absorbing material or light reflecting material) is disposed (formed or laminated) on the side surface (wall surface) of the hole dug by the silicon trench and the back surface of the semiconductor substrate 10. On the other hand, no light shielding material is disposed on the bottom surface of the hole which is the light receiving surface of the photodiode. Then, the wall surface of the hole dug by the silicon trench becomes the wall surface of the angle limiting filters 41 and 42, and the incident light having the angle more than the limiting angle is shielded from entering the photodiodes 31 and 32. The aspect ratios of the angle limiting filters 41 and 42 are set according to the transmission wavelength band (for example, BW1 and BW2 described above in FIG. 12B).

On the angle limiting filters 41, 42, an insulating film 70 filling the openings (hollow portions) of the angle limiting filters 41, 42 is formed. For example, the insulating film 70 is formed of an insulating film such as SiO ₂ (silicon oxide film). The insulating film 70 is not necessarily insulative and may be a material that is transparent to the wavelength detected by the photodiodes 31 and 32.

  On the insulating film 70, the inclined structure 50 is formed. The inclined structure 50 has inclined surfaces with inclination angles θ1 and θ2 according to the transmission wavelengths of the optical bandpass filters 61 and 62. On the inclined structure 50, a multilayer thin film 60 that forms the optical bandpass filters 61 and 62 is laminated. The transmission wavelength bands of the optical bandpass filters 61 and 62 are determined by the inclination angles θ1 and θ2 of the inclined structure 50 and the limiting angles of the angle limiting filters 41 and 42.

  The first to fourth modifications described above can also be applied to this second detailed configuration example. That is, the inclined structure 50 may be formed of low-melting glass or the like and attached on the angle limiting filters 41 and 42. A multilayer thin film parallel to the semiconductor substrate 10 may be formed for each transmission wavelength. The photodiodes 31 and 32 may be divided into a plurality of photodiodes by STI. Further, an MLA for increasing the amount of received light may be provided at the openings of the angle limiting filters 41 and 42.

  According to the second detailed configuration example, the angle limiting filters 41 and 42 are provided with a light shielding material (light absorption) on the back side surface and the wall surface from the back side of the semiconductor substrate 10 to the impurity regions for the photodiodes 31 and 32. And a light receiving hole in which a film, a light reflecting film, a light absorbing film and a light reflecting film) are provided.

  Thereby, since the spectroscopic sensor can be configured using a semiconductor process or MEMS technology, the spectroscopic sensor can be miniaturized. That is, the photodiodes 31 and 32 are formed by a semiconductor process, and the angle limiting filters 41 and 42 are formed by excavating the back surface of the semiconductor substrate 10, so that fine processing can be easily performed and the size can be reduced.

  In the present embodiment, the angle limiting filters 41 and 42 are formed along the outer periphery of the light receiving region (for example, the region LRA shown in FIG. 17) of the photodiodes 31 and 32 in a plan view with respect to the semiconductor substrate 10. Specifically, a plurality of light receiving regions are set in the impurity regions for the photodiodes 31 and 32, and a plurality of openings are formed along the outer periphery of the plurality of light receiving regions. For example, as shown in FIG. 16, a square light shielding material surrounds each light receiving region in plan view, and the angle limiting filters 41 and 42 are formed by arranging the squares in a lattice shape.

  In this way, the angle limiting filters 41 and 42 are formed along the outer periphery of each light receiving region of the photodiodes 31 and 32, thereby limiting the incident angle of incident light with respect to each light receiving region of the photodiodes 31 and 32. it can.

8). Second Method for Manufacturing Spectroscopic Sensor An example of a method for manufacturing a spectroscopic sensor having a second detailed configuration example will be described with reference to FIGS.

  First, as shown in S101 of FIG. 18, a photodiode and a wiring layer are formed on the surface side of the substrate by the above-described steps in S1 to S6 of FIG. Then, as shown in S102, a protective film (passivation) is formed on the insulating film by a polyimide coating and curing process.

  Next, as shown in S103, the back surface of the P-type silicon substrate is ground to adjust the thickness of the P-type silicon substrate. Then, as shown in S104, a silicon trench is formed by photolithography, anisotropic dry etching of a P-type silicon substrate, and a photoresist peeling process.

Next, as shown in S105, a TiN light absorption film (antireflection film) is formed on the side surface (inner wall) of the silicon trench and the back surface of the semiconductor substrate by the process of TiN film deposition and TiN film anisotropic dry etching. Form. Then, as shown in S106, (shown by dashed lines) deposition of the SiO ₂ film, the step of flattening the SiO ₂ film by CMP, to embed the silicon trench. In this way, the angle limiting filter is formed by the steps S103 to S106.

Next, as shown in S107 of FIG. 19, deposition of the SiO ₂ film, photolithography, anisotropic dry etching of SiO ₂ film, by a process of photoresist stripping, to form a step or sparse and dense pattern of the insulating film. Then, as shown in S108, the inclined surface of the inclined structure is formed by the step of polishing the SiO ₂ film by CMP. At this time, the inclined surface of the inclined structure is processed at an inclination angle corresponding to the step of the insulating film and the shape of the dense pattern.

Next, as shown in S109 of FIG. 20, sputtering of TiO ₂ (titanium oxide film) and sputtering of SiO ₂ are performed alternately to form a multilayer thin film on the inclined surface. The TiO ₂ film is a thin film having a high refractive index, and the SiO ₂ film is a thin film having a lower refractive index than the TiO ₂ film.

9. Electronic Device FIG. 21 shows a configuration example of an electronic device including the spectroscopic sensor device of the present embodiment. For example, a pulse meter, a pulse oximeter, a blood glucose level measuring device, a fruit sugar meter, and the like are assumed as electronic devices.

  The electronic device illustrated in FIG. 21 includes a spectroscopic sensor device 900, a microcomputer 970 (CPU), a storage device 980, and a display device 990. The spectroscopic sensor device 900 includes an LED 950 (light source), an LED driver 960, and a spectroscopic sensor 910. The spectroscopic sensor 910 is integrated in, for example, a one-chip IC, and includes a photodiode 920, a detection circuit 930, and an A / D conversion circuit 940.

  The LED 950 irradiates the observation target with, for example, white light. The spectroscopic sensor device 900 separates reflected light and transmitted light from the observation target and acquires signals of each wavelength. The microcomputer 970 controls the LED driver 960 and acquires a signal from the spectroscopic sensor 910. The microcomputer 970 displays a display based on the acquired signal on a display device 990 (for example, a liquid crystal display device), and stores data based on the acquired signal in a storage device 980 (for example, a memory or a magnetic disk).

  Although the present embodiment has been described in detail as described above, it will be easily understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention. For example, in the specification or drawings, terms (photodiodes, optical bandpass filters, silicon substrates, etc.) described at least once together with different terms (photosensors, thin film filters, semiconductor substrates, etc.) having a broader meaning or the same meaning are used in the specification. The different terms can be used anywhere in the book or drawing. Further, the configuration and operation of the spectroscopic sensor, spectroscopic sensor device, electronic device, and the like are not limited to those described in this embodiment, and various modifications can be made.

10 semiconductor substrate, 20 circuit, 31, 32 photodiode,
41, 42 Angle limiting filter, 50 inclined structure, 60 multilayer thin film,
61, 62 Optical band pass filter, 70 insulating layer, 80 adhesive layer,
90 trench, 95 micro lens array,
100 spectroscopic sensor, 110 light source unit, 111-114 plural light sources,
120 light shielding member, 130 display panel, 140 operation input unit, 150 EL substrate,
900 spectroscopic sensor device, 910 spectroscopic sensor, 920 photodiode,
930 detection circuit, 940 A / D conversion circuit, 950 LED,
960 LED driver, 970 microcomputer, 980 storage device,
990 display device,
BW1, BW2 transmission wavelength band, LRA light receiving region, θ1, θ2 tilt angle,
λ1, λ2 transmission wavelength

Claims (10)

A first light source unit for irradiating the observation target with the first irradiation light;
A second light source unit that irradiates the observation target with the second irradiation light;
A detection unit for detecting the first irradiation light and the second irradiation light reflected by the observation target;
A light shielding member having a first light shielding member and a second light shielding member;
Including
The detection unit is provided between the first light source unit and the second light source unit,
The first light shielding member is provided between the first light source unit and the detection unit, and the second light shielding member is provided between the second light source unit and the detection unit ,
The detector is
A photosensor portion having an impurity region;
An angle limiting filter that includes a light shielding material and limits an incident angle of the first irradiation light and the second irradiation light incident on the photosensor unit;
Have
A plurality of the light shielding materials are arranged at a pitch set by a limit angle of the incident angle with respect to a height from the impurity region of the light shielding material to the incident ends of the first irradiation light and the second irradiation light. A pulse sensor formed on the impurity region of the photosensor unit . In claim 1,
The first light blocking member blocks direct light from the first light source unit to the detection unit,
The pulse sensor, wherein the second light blocking member blocks direct light from the second light source unit to the detection unit. In claim 1 or 2,
The pulse sensor, wherein the light shielding member surrounds the detection unit. In any one of Claims 1 thru | or 3,
The pulse sensor, wherein the first light shielding member and the second light shielding member have end faces in contact with the observation target when the pulse sensor is used. In any one of Claims 1 thru | or 4,
The pulse sensor, wherein the observation object is a human body. In any one of Claims 1 thru | or 5,
The direction from the first light source unit to the detection unit is a first direction, the direction from the second light source unit to the detection unit is a second direction, and the direction intersects the first direction. In the use, the direction from the first light source unit toward the observation object is a third direction, the direction intersects the second direction, and the second light source unit is used in the use. When the direction from the object to the observation object is the fourth direction,
Of the first irradiation light, the light irradiated in the third direction and reflected by the observation target, and the second irradiation light irradiated in the fourth direction and irradiated by the observation target. The reflected light is incident on the detection unit,
Of the first irradiation light, the light irradiated in the first direction is blocked by the first light shielding member, and among the second irradiation light, the light irradiated in the second direction is A pulse sensor which is shielded from light by the second light shielding member. In any one of Claims 1 thru | or 6.
The detector is
A band pass filter before Symbol photosensor unit transmits light of a detectable wavelength band,
A pulse sensor characterized by comprising: A first light source unit for irradiating the observation target with the first irradiation light;
A second light source unit that irradiates the observation target with the second irradiation light;
A detection unit for detecting the first irradiation light and the second irradiation light reflected by the observation target;
A light shielding member having a first light shielding member and a second light shielding member;
Including
The detection unit is provided between the first light source unit and the second light source unit,
The first light shielding member is provided between the first light source unit and the detection unit, and the second light shielding member is provided between the second light source unit and the detection unit ,
The first light-shielding member and the second light-shielding member each have an end surface that is in contact with the observation target when the pulse sensor is used.
The detector is
A photo sensor section;
An angle limiting filter for limiting an incident angle of the first irradiation light and the second irradiation light incident on the photosensor unit;
Pulse sensor, characterized in that it comprises a. In claim 8,
The photo sensor unit has an impurity region,
The angle limiting filter has a light shielding material,
A plurality of the light shielding materials are arranged at a pitch set by a limit angle of the incident angle with respect to a height from the impurity region of the light shielding material to the incident ends of the first irradiation light and the second irradiation light. A pulse sensor formed on the impurity region of the photosensor unit.   A pulse meter comprising the pulse sensor according to claim 1.

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