JP2015028487A - Spectroscopic sensor and angle limiting filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve downsizing of a spectroscopic sensor and an angle limiting filter, and also to improve the surface flatness of the angle limiting filter.SOLUTION: An angle limiting filter includes: a first light-shielding layer which includes a first light-shielding material and which has a first opening provided therein; a second light-shielding layer which includes a second light-shielding material and which is located in a region surrounding the first light-shielding layer; a third light-shielding layer which includes the first light-shielding material, which has a second opening provided therein so as to be at least partially overlapped with the first opening, and which is located above the first light-shielding layer; and a fourth light-shielding layer which includes the second light-shielding material and which is located in a region surrounding the third light-shielding layer and is located above the second light-shielding layer.

Description

  The present invention relates to a spectroscopic sensor and an angle limiting filter.

  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.

  Patent Document 1 listed below discloses a spectral imaging sensor that limits a transmission wavelength band to a photoelectric conversion element by limiting an incident angle with an optical fiber that optically connects an interference filter and the photoelectric conversion element. ing.

JP-A-6-129908

  However, the conventional spectral sensor has a problem that it is difficult to reduce the size. For this reason, it becomes difficult to install a large number of sensors at desired locations or to install them at all times.

  The present invention has been made in view of the above technical problems. Some aspects of the invention relate to miniaturizing spectroscopic sensors and angle limiting filters.

In some aspects of the present invention, the angle limiting filter includes a first light-shielding material, includes a first light-shielding layer provided with a first opening, a second light-shielding material, and A second light-shielding layer located in a region surrounding the one light-shielding layer, a second light-shielding material containing a first light-shielding material, and a second opening at least partially overlapping with the first light-shielding layer. A third light shielding layer located above the layer, and a fourth light shielding layer that includes the second light shielding material and surrounds the third light shielding layer and is located above the second light shielding layer, ,including.
According to this aspect, the configuration in which the light path is formed by the light shielding layer enables the formation of a fine pattern and the manufacture of a small angle limiting filter. In addition, since the second light-shielding layer and the fourth light-shielding layer are respectively provided in the region surrounding the first light-shielding layer and the region surrounding the third light-shielding layer, an angle limiting filter with high surface flatness is manufactured. Is possible.

In the above-described aspect, it is desirable that the first light shielding layer is in contact with the end face of the second light shielding layer, and the third light shielding layer is in contact with the end face of the fourth light shielding layer.
According to this, it is possible to suppress light from passing between the first light shielding layer and the second light shielding layer and between the third light shielding layer and the fourth light shielding layer. Moreover, when these light shielding layers are conductors, electrical continuity can be obtained between these light shielding layers.

In the above-described aspect, the first light shielding layer includes a plurality of first openings, a first portion located between two adjacent first openings, and a first portion. And a second portion located on the second light shielding layer side from the plurality of first openings, and the end surface of the second light shielding layer is the center of the width of the second portion of the first light shielding layer It is desirable that the first light shielding layer is covered.
According to this, since the end surface of the second light shielding layer is located at the center of the width of the second portion of the first light shielding layer, it is possible to prevent the second light shielding layer from being exposed in the optical path. Moreover, when these light shielding layers are conductors, electrical continuity can be more reliably obtained between these light shielding layers.

In the above aspect, there is a gap between the first light shielding layer and the third light shielding layer, and both the first light shielding layer and the third light shielding layer are part of the fourth light shielding layer. May be in contact with.
According to this, even if there is a gap between the third light shielding layer and the fifth light shielding layer, electrical conduction can be obtained by interposing the sixth light shielding layer.

In the above-described aspect, it is desirable that the reflectance of the first light shielding material is lower than the reflectance of the second light shielding material.
The first and third light shielding layers are preferably made of a material having a lower reflectance than aluminum.

  According to this, the light passing through the optical path by hitting the wall surface of the optical path can be reduced by configuring the light shielding layer with the material having low light reflectance. Therefore, even a small angle limiting filter can prevent light having an incident angle exceeding the limiting angle range from passing through the optical path.

In another aspect of the present invention, the spectroscopic sensor detects the above-described angle limiting filter, a wavelength limiting filter that limits the wavelength of light that can pass through the angle limiting filter, and light that has passed through the angle limiting filter and the wavelength limiting filter. A light receiving element.
According to this aspect, since the above-mentioned angle limiting filter is used, a small spectroscopic sensor can be manufactured. Further, the wavelength of transmitted light can be selected by inclining the optical path of the angle limiting filter without forming an inclined structure for inclining the wavelength limiting filter.
Note that “upward” means a direction opposite to the direction toward the back surface with respect to the front surface of the substrate.

The figure which shows the angle limiting filter and spectral sensor which concern on 1st Embodiment. Sectional drawing which shows the angle limiting filter and spectroscopic sensor which concern on 1st Embodiment. Sectional drawing which shows the formation process of the angle limiting filter which concerns on 1st Embodiment. Sectional drawing which shows a part of angle limiting filter and wiring layer which concern on 2nd Embodiment. Sectional drawing which shows a part of angle limiting filter and wiring layer which concern on 3rd Embodiment. The top view which shows the angle limiting filter and spectral sensor which concern on 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, this embodiment demonstrated below does not unduly limit the content of this invention described in the claim. Further, not all of the configurations described in the present embodiment are essential as a solution means of the present invention. The same constituent elements are denoted by the same reference numerals, and description thereof is omitted.

<1. First Embodiment>
FIG. 1 is a schematic diagram showing an angle limiting filter and a spectroscopic sensor according to the first embodiment of the present invention. 1A is a plan view of the spectroscopic sensor, and FIG. 1B is a cross-sectional view taken along the line BB of FIG. 1A. FIG. 2 is a cross-sectional view showing the angle limiting filter and the spectroscopic sensor according to the first embodiment. FIG. 2 corresponds to an enlarged view of the encircled line II portion shown in FIG.
The spectroscopic sensor 1 includes an angle limiting filter 10, a wavelength limiting filter 20, and a light receiving element 30 (see FIG. 1B). In FIG. 1A, the wavelength limiting filter 20 is omitted.

  A P-type silicon substrate 3 (see FIG. 2) as a semiconductor substrate on which the spectroscopic sensor 1 is formed is applied with a predetermined reverse bias voltage to the light receiving element 30 or a current based on the photovoltaic force generated in the light receiving element 30. And an electronic circuit including a semiconductor element 40 that amplifies an analog signal corresponding to the magnitude of the current and converts it into a digital signal. By connecting any one of a plurality of aluminum (Al) alloy layers 51b to 51f for wiring to the semiconductor element 40, electrical connection between the semiconductor elements in the electronic circuit and electrical connection to the outside of the electronic circuit are performed. Has been done.

  Silicon oxide layers 52b to 52e are formed between the plurality of aluminum alloy layers 51b to 51f, and a silicon oxide layer 52a is formed between the lowermost aluminum alloy layer 51b and the semiconductor element 40. Yes. Conductive plugs 53a to 53e are connected between the aluminum alloy layers 51b to 51f and between the lowermost aluminum alloy layer 51b and the semiconductor element 40, respectively. The conductive plugs 53a to 53e are electrically connected between the upper and lower aluminum alloy layers 51b to 51f or between the lowermost aluminum alloy layer 51b and the semiconductor element 40 at the positions where the conductive plugs 53a to 53e are disposed. To do. A titanium nitride (TiN) film may be formed on the upper and lower surfaces of each of the aluminum alloy layers 51b to 51f in order to improve electrical connection with the conductive plugs 53a to 53e.

<1-1. Angle limit filter>
The angle limiting filter 10 is formed on the P-type silicon substrate 3 on which the light receiving element 30 is formed. In the angle limiting filter 10 of the present embodiment, a wall portion that defines an optical path is formed by tungsten (W) layers 13b to 13e as a plurality of light shielding layers (first, third, and fifth light shielding layers). ing. Each of the tungsten layers 13 b to 13 e has at least one opening 15. The first, third, and fifth light shielding layers are not limited to the tungsten layers 13b to 13e, and the reflectance of light having a wavelength to be received by the light receiving element 30 is lower than the reflectance of aluminum. You may be comprised with the substance which does not permeate | transmit the light of the wavelength which is going to receive light substantially, for example, copper, titanium nitride, titanium tungsten, titanium, tantalum, tantalum nitride, chromium, molybdenum.

On the P-type silicon substrate 3, aluminum alloy layers 11 b to 11 f as a plurality of light shielding layers (second, fourth, and sixth light shielding layers) are translucent (to receive light by the light receiving element 30). It is laminated through silicon oxide (SiO ₂ ) layers 12b to 12e as insulating layers having a light-transmitting property with respect to light having a wavelength of the same. Note that the second, fourth, and sixth light shielding layers are not limited to the aluminum alloy layers 11b to 11f, and a copper (Cu) alloy layer may be formed.

  The tungsten layers 13b to 13e are continuously formed on the P-type silicon substrate 3 over a plurality of layers, for example, in a lattice-shaped predetermined pattern. Thereby, the openings 15 formed in each of the tungsten layers 13b to 13e overlap each other. The regions corresponding to the openings 15 of the tungsten layers 13b to 13e are filled with the above-described silicon oxide layers 12b to 12e having translucency. An optical path along the stacking direction of the tungsten layers 13b to 13e is formed by the opening 15 formed in each of the tungsten layers 13b to 13e.

  The wall portion formed by the tungsten layers 13b to 13e limits the incident angle of light passing through the optical path. That is, when the light incident on the optical path is inclined with respect to the direction of the optical path, the light hits any one of the tungsten layers 13b to 13e, and a part of the light hits any one of the tungsten layers 13b to 13e. Absorbed and the rest is reflected. Since the reflected light becomes weak due to repeated reflections before passing through the optical path, the light that can pass through the angle limiting filter 10 is substantially limited to light having an inclination with respect to the optical path within a predetermined limiting angle range. The

  In the above-described aspect, since the wall portion is formed by forming the plurality of tungsten layers 13b to 13e in a lattice-like predetermined pattern on the P-type silicon substrate 3, it is possible to form a fine pattern. A small angle limiting filter 10 can be manufactured. Moreover, compared with the case where a spectroscopic sensor is comprised by bonding a member with an adhesive material, a manufacturing process can be simplified and the reduction | decrease of the transmitted light by an adhesive material can also be suppressed.

  In a preferred embodiment, the aluminum alloy layers 11b to 11f are made of the same material as the aluminum alloy layers 51b to 51f on the electronic circuit including the semiconductor element 40, and are formed by the same multilayer wiring process. The tungsten layers 13b to 13e are made of the same material (tungsten) as the conductive plugs 53b to 53e on the electronic circuit, and are formed by the same multilayer wiring process. As a result, the angle limiting filter 10 simultaneously forms the aluminum alloy layers 51b to 51f for wiring and the conductive plugs 53b to 53e for the electronic circuit formed on the same P-type silicon substrate 3, and simultaneously with the semiconductor process. Can be formed.

  In the angle limiting filter 10 of the present embodiment, the aluminum alloy layers 11b to 11f are formed in a region surrounding the wall portion formed by the tungsten layers 13b to 13e (see FIG. 1A). Further, the wall surface of the optical path of the angle limiting filter 10 is formed only by the tungsten layers 13b to 13e, not the aluminum alloy layers 11b to 11f having high light reflectance (see FIG. 2). Thereby, since it can suppress that the light which injected into the optical path reflects on the wall surface of an optical path, the light of the incident angle exceeding a limit angle range can be made difficult to pass through the optical path. When the aluminum alloy layer is formed in the region surrounding the wall portion, the aluminum alloy layer does not have to surround the wall portion, and there may be a gap.

  In a preferred embodiment, the tungsten layers 13b to 13e are electrically connected to the aluminum alloy layers 11b to 11e through the inner end surfaces of the aluminum alloy layers 11b to 11e, respectively. For example, the light receiving element 30 formed on the P-type silicon substrate 3 and the tungsten layer 13b are electrically connected by the lowermost tungsten layer 13a. Thereby, the light receiving element 30 and the aluminum alloy layers 11b to 11f are electrically connected.

  In the tungsten layers 13b to 13e, the width of the portion (first portion) 131 located between the two adjacent openings 15 is narrow, and the width of the outer portion (second portion) 132 is wide. Yes. The inner end faces of the aluminum alloy layers 11b to 11e are located at the center of the width of the outer portion 132. As a result, both the tungsten layers 13b to 13e and the aluminum alloy layers 11b to 11e are electrically connected, and the aluminum alloy layers 11b to 11e are not exposed in the optical path of the angle limiting filter 10. Can be realized more reliably.

  Further, since the inner end faces of the aluminum alloy layers 11b to 11e are in contact with the tungsten layers 13b to 13e, light strays from the outside of the tungsten layers 13b to 13e (the tungsten layers 13b to 13e and the aluminum alloy layers 11b to 11e and It is possible to suppress the light from passing between the light-receiving elements 30.

  In the present embodiment, the angle limiting filter 10 has an optical path in a direction perpendicular to the P-type silicon substrate 3, but is not limited thereto, and has an optical path in a direction inclined with respect to the P-type silicon substrate 3. You may do it. In order to form an optical path in an inclined direction with respect to the P-type silicon substrate 3, for example, the plurality of tungsten layers 13b to 13e are formed so as to be shifted by a predetermined amount in the plane direction.

<1-2. Wavelength limiting filter>
For example, the wavelength limiting filter 20 is formed by laminating a number of low refractive index thin films 21 such as silicon oxide (SiO ₂ ) and high refractive index thin films 22 such as titanium oxide (TiO ₂ ) on the angle limiting filter 10. Is.
The low-refractive index thin film 21 and the high-refractive index thin film 22 each have a predetermined thickness of, for example, a submicron order, and are laminated over a total of, for example, about 60 layers, for example, to have a total thickness of, for example, about 6 μm.

  Each of the low refractive index thin film 21 and the high refractive index thin film 22 may be slightly inclined with respect to the P-type silicon substrate 3. The inclination angle θ (see FIG. 2) of the low refractive index thin film 21 and the high refractive index thin film 22 with respect to the P-type silicon substrate 3 is, for example, 0 [deg] according to the set wavelength of light to be received by the light receiving element 30. ] To 30 [deg] or less.

  In order to incline the low refractive index thin film 21 and the high refractive index thin film 22 with respect to the P-type silicon substrate 3, for example, an inclined structure 23 having translucency is formed on the angle limiting filter 10, and the inclined structure is formed. A thin film 21 having a low refractive index and a thin film 22 having a high refractive index are formed on the body 23. The inclined structure 23 is formed, for example, by processing silicon oxide formed on the angle limiting filter 10 by a CMP (chemical mechanical polishing) method.

  By forming an inclined structure 23 having an inclination angle θ corresponding to a set wavelength of light to be received by the light receiving element 30, the low refractive index thin film 21 and the high refractive index thin film 22 with respect to the P-type silicon substrate 3. The tilt angle can be adjusted.

With the above configuration, the wavelength limiting filter 20 limits the wavelength of light (light that can pass through the angle limiting filter 10) that enters the angle limiting filter 10 within a predetermined limiting angle range.
That is, the incident light incident on the wavelength limiting filter 20 is partially reflected light and partially transmitted light at the boundary surface between the low refractive index thin film 21 and the high refractive index thin film 22. A part of the reflected light is reflected again at the interface between the other thin film 21 having a low refractive index and the thin film 22 having a high refractive index, and is combined with the above-described transmitted light. At this time, the light of the wavelength that matches the optical path length of the reflected light strengthens the reflected light and the transmitted light in phase, and the light of the wavelength that does not match the optical path length of the reflected light intensifies the phase of the reflected light and transmitted light. Weaken (interfer) without matching.

  Here, the optical path length of the reflected light is determined by the inclination angles of the low refractive index thin film 21 and the high refractive index thin film 22 with respect to the direction of the incident light. Therefore, when the above-described interference action is repeated in, for example, the low-refractive index thin film 21 and the high-refractive index thin film 22 covering a total of 60 layers, only light of a specific wavelength is wavelength-limited according to the incident angle of incident light. The light passes through the filter 20 and is emitted from the wavelength limiting filter 20 at a predetermined emission angle (for example, the same angle as the incident angle to the wavelength limiting filter 20).

The angle limiting filter 10 allows only light incident on the angle limiting filter 10 to pass within a predetermined limit angle range. Therefore, the wavelength of the light passing through the wavelength limiting filter 20 and the angle limiting filter 10 is determined by the inclination angle θ of the low refractive index thin film 21 and the high refractive index thin film 22 with respect to the P-type silicon substrate 3 and the angle limiting filter 10. The wavelength is limited to a predetermined range determined by the limit angle range of the incident light to be transmitted.
The wavelength limiting filter is not limited to the above example, and may be a material that transmits light in a specific range of wavelengths. Also, a prism that separates light of a specific range of wavelengths may be used.

<1-3. Light receiving element>
The light receiving element 30 is an element that receives light that has passed through the wavelength limiting filter 20 and the angle limiting filter 10 and converts it into photovoltaic power.

  The light receiving element 30 includes various semiconductor regions formed in the P-type silicon substrate 3 by ion implantation or the like. As the semiconductor region formed on the P-type silicon substrate 3, for example, a first conductivity type first semiconductor region 31 and a second conductivity type second semiconductor region formed on the first semiconductor region 31 are used. 32, a third semiconductor region 33 of the first conductivity type formed on the second semiconductor region 32, and a second semiconductor region 32 surrounded by the third semiconductor region 33, and And a fourth semiconductor region 34 of the second conductivity type that contains a higher concentration of impurities than the second semiconductor region 32. The first conductivity type is, for example, N type, and the second conductivity type is, for example, P type.

  The first semiconductor region 31 and the third semiconductor region 33 are electrically connected via a first conductivity type fifth semiconductor region 35. The first semiconductor region 31 is connected to the conductive plug 63a through the fifth semiconductor region 35, and the conductive plug 63a is connected to the first unillustrated first through the aluminum alloy layer 61b separated from the aluminum alloy layer 11b. Connected to the external electrode. The fourth semiconductor region 34 is connected to the tungsten layer 13a at the lower end of the angle limiting filter 10, and the angle limiting filter 10 is further connected to a second external electrode (not shown) via the aluminum alloy layers 11b to 11f. . A reverse bias voltage can be applied to the PN junction formed between the first semiconductor region 31 and the second semiconductor region 32 by the first external electrode and the second external electrode.

  In the above aspect, since the fourth semiconductor region 34 is connected to the second external electrode via the angle limiting filter 10, a wiring conductor other than the angle limiting filter 10 is provided on the light receiving element 30. There is no need, and a decrease in the amount of received light due to an increase in wiring can be suppressed.

  When the light passing through the angle limiting filter 10 is received by the light receiving element 30, a photovoltaic force is generated at the PN junction formed between the first semiconductor region 31 and the second semiconductor region 32. Current is generated. By detecting this current by an electronic circuit (including the semiconductor element 40) connected to the second external electrode, the light received by the light receiving element 30 can be detected.

<1-4. Manufacturing Method of First Embodiment>
Here, a method for manufacturing the spectroscopic sensor 1 according to the first embodiment will be described. In the spectroscopic sensor 1, the light receiving element 30 is first formed on the P-type silicon substrate 3, then the angle limiting filter 10 is formed on the light receiving element 30, and then the wavelength limiting filter is formed on the angle limiting filter 10. 20 is produced.

  First, the light receiving element 30 is formed on the P-type silicon substrate 3. For example, first, an N-type first semiconductor region 31 is formed by performing ion implantation or the like on the P-type silicon substrate 3. Then, further ion implantation or the like is performed on the first semiconductor region 31 to form an N-type fifth semiconductor region 35 and a P-type second semiconductor region 32. Then, further ion implantation or the like is performed on the second semiconductor region 32 to form a P-type fourth semiconductor region 34 and an N-type third semiconductor region 33. This step can be performed simultaneously with the formation of the electronic circuit including the semiconductor element 40 formed on the same P-type silicon substrate 3.

Next, the angle limiting filter 10 is formed on the light receiving element 30.
FIG. 3 is a cross-sectional view showing a process of forming an angle limiting filter according to the first embodiment. In FIG. 3, the illustration of the P-type silicon substrate 3 is omitted.

(1) First, the silicon oxide layer 12a is formed on the P-type silicon substrate 3 on which the light receiving element 30 is formed. Next, a groove is formed in the silicon oxide layer 12a by etching a part of the silicon oxide layer 12a (region above the fourth semiconductor region 34).
Next, the tungsten layer 13a is embedded in the groove formed in the silicon oxide layer 12a. The tungsten layer 13a is formed simultaneously with the formation of the conductive plug 53a that connects the aluminum alloy layer for wiring for the electronic circuit and the semiconductor element included in the electronic circuit (FIG. 3A).

  (2) Next, the aluminum alloy layers 11b and 61b are formed simultaneously with the formation of the aluminum alloy layer 51b for wiring for an electronic circuit. A titanium nitride film or the like is desirably formed on the lower and upper surfaces of the aluminum alloy layers 11b and 61b. Next, the silicon oxide layer 12b is formed on the silicon oxide layer 12a and the aluminum alloy layers 11b and 61b. The silicon oxide layer 12b is formed simultaneously with the formation of the silicon oxide layer 52b on the aluminum alloy layer 51b for wiring for an electronic circuit.

  Next, the silicon oxide layer 12b is planarized by CMP (FIG. 3B). At this time, not only the aluminum alloy layer 51b is located on the region where the electronic circuit is formed, but also the aluminum alloy layers 11b and 61b are located on the periphery of the region where the light receiving element 30 is formed. As a result, it is possible to prevent the silicon oxide layer 12b on the region where the light receiving element 30 is formed from being excessively shaved and impairing the flatness (CMP dishing). In order to suppress such CMP dishing, it is desirable that the length of one piece of the aluminum alloy layers 11b and 61b is, for example, 300 μm or less, and the total width of the aluminum alloy layers 11b, 61b is, for example, 6 μm or more.

  (3) Next, a part of the silicon oxide layer 12b is etched to form a groove in the silicon oxide layer 12b. Next, a tungsten layer 13b is embedded in the groove formed in the silicon oxide layer 12b (FIG. 3C). The tungsten layer 13b is formed simultaneously with the formation of the conductive plug 53b that connects the aluminum alloy layers 51b and 51c for wiring for an electronic circuit.

The angle limiting filter 10 is formed by repeating the steps (2) and (3) described above a predetermined number of times (FIGS. 3D and 3E).
The aluminum alloy layers 11c to 11f are positioned on the periphery of the region where the light receiving element 30 is formed not only in the step of planarizing the silicon oxide layer 12b but also in the step of planarizing the silicon oxide layers 12c to 12f. doing. Thereby, it can suppress that the silicon oxide layers 12c-12f on the area | region in which the light receiving element 30 was formed are shaved too much, and impairing flatness (CMP dishing). In order to suppress such CMP dishing, it is desirable that the length of one piece of the aluminum alloy layers 11c to 11f is, for example, 300 μm or less, and the width of the aluminum alloy layers 11c to 11f is, for example, 6 μm or more.

Next, the wavelength limiting filter 20 is formed on the angle limiting filter 10 (see FIG. 2). For example, first, a silicon oxide layer is formed on the angle limiting filter 10, and this silicon oxide layer is processed into a tilted structure 23 having a predetermined angle by a CMP method or the like. Next, a large number of low refractive index thin films 21 and high refractive index thin films 22 are alternately stacked.
The spectroscopic sensor 1 is manufactured through the above steps.

<2. Second Embodiment>
FIG. 4 is a cross-sectional view showing a part of the angle limiting filter and the wiring layer according to the second embodiment of the present invention.

  In the second embodiment, the thickness of the aluminum alloy layer 11e (and 11f) is larger than the thickness of the aluminum alloy layers 11b to 11d. In such a case, when the trench is formed in the silicon oxide layer 12e and the tungsten layer 13e is embedded, the trench formed in the silicon oxide layer 12e is formed in order to connect the tungsten layer 13e to the underlying tungsten layer 13d. Need to be deep. However, when the step of forming the groove in the silicon oxide layer 12e and the step of forming the groove in the silicon oxide layer 52e are performed in a common step, if the etching time of the silicon oxide layers 12e and 52e is lengthened, The titanium nitride (TiN) film on the surface of the aluminum alloy layer 51e is etched, and the electrical resistance between the aluminum alloy layer 51e and the conductive plug 53e may increase.

  Therefore, in the second embodiment, the depth of the groove formed in the silicon oxide layer 12e is equal to the depth of the groove formed in the other silicon oxide layers 12b to 12d, whereby the tungsten layer 13e and the tungsten layer 13d are formed. A gap was formed between them.

On the other hand, when the tungsten layers 13a to 13d are connected to the light receiving element 30 and used as a part of an electric circuit, stray capacitance may occur due to a gap between the tungsten layer 13e and the tungsten layer 13d. In order to prevent this, in the second embodiment, the widths of the tungsten layer 13e and the outer portion 132 of the tungsten layer 13d so that the aluminum alloy layer 11e is connected to both the tungsten layer 13e and the tungsten layer 13d. The inner end face of the aluminum alloy layer 11e is located at the center of the center.
The other points are the same as in the first embodiment.

<3. Third Embodiment>
FIG. 5 is a cross-sectional view showing a part of the angle limiting filter and the wiring layer according to the third embodiment of the present invention.

In the third embodiment, an aluminum alloy layer is not formed on the silicon oxide layer 12e and the uppermost tungsten layer 13e. In the first embodiment, since the aluminum alloy layer 11f is formed on the silicon oxide layer 12e and the tungsten layer 13e, and the silicon oxide layer 12f is further formed thereon, after the silicon oxide layer 12f is formed, It was necessary to planarize the silicon oxide layer 12f. In contrast, in the third embodiment, since the silicon oxide layer 12f is formed on the silicon oxide layer 12e and the uppermost tungsten layer 13e without forming the aluminum alloy layer, the silicon oxide layer 12f is formed. The silicon oxide layer 12f is formed flat only by filming. Therefore, in the third embodiment, the step of planarizing the silicon oxide layer 12f can be omitted.
Other points are the same as those in the first embodiment and the second embodiment.

<4. Fourth Embodiment>
FIG. 6 is a plan view showing an angle limiting filter and a spectroscopic sensor according to the fourth embodiment of the present invention. In addition to the angle limiting filter 10, an electronic circuit 41 including semiconductor elements, a power supply wiring 42, and a pad electrode 43 are also shown in FIG.

  The spectroscopic sensor 1a according to the fourth embodiment includes a large-area angle limiting filter 10a in which a plurality of angle limiting filters 10 in which the aluminum alloy layers 11b to 11e are arranged in the periphery in the first embodiment are arranged on a semiconductor chip. It is out. Since the angle limiting filter 10a has the angle limiting filter 10 in which the aluminum alloy layers 11b to 11e are arranged around, the angle limiting filter 10a can be made to have a high flatness.

The other points are the same as in the first embodiment.
The angle limiting filter according to the second and third embodiments described above can be applied to the spectroscopic sensor according to the first embodiment and the spectroscopic sensor according to the fourth embodiment.

  DESCRIPTION OF SYMBOLS 1, 1a ... Spectroscopic sensor, 3 ... P type silicon substrate (semiconductor substrate), 10, 10a ... Angle limiting filter, 11b-11f ... Aluminum alloy layer (2nd, 4th, 6th light shielding layer), 12a-12f ... silicon oxide layer (insulating layer), 13a to 13e ... tungsten layer (first, third and fifth light shielding layers), 15 ... opening, 20 ... wavelength limiting filter, 21 ... low refractive index thin film, 22 ... High refractive index thin film, 23 ... inclined structure, 30 ... light receiving element, 31 ... first semiconductor region, 32 ... second semiconductor region, 33 ... third semiconductor region, 34 ... fourth semiconductor region, 35 ... 5th semiconductor region, 40 ... Semiconductor element, 41 ... Electronic circuit, 42 ... Power supply wiring, 43 ... Pad electrode, 51b-51f ... Aluminum alloy layer, 52a-52f ... Silicon oxide layer, 53a-53e ... Conductive plug , 6 b ... aluminum alloy layer, 63a ... conductive plug.

Claims (7)

A first light shielding layer comprising a first light shielding material and provided with a first opening;
A second light-shielding layer that includes a second light-shielding material and is located in a region surrounding the first light-shielding layer;
A third light-shielding layer comprising the first light-shielding material, provided with a second opening at least partially overlapping with the first opening, and positioned above the first light-shielding layer;
A fourth light-shielding layer that includes the second light-shielding material and surrounds the third light-shielding layer and is located above the second light-shielding layer;
Including angle limiting filter. In claim 1,
The angle limiting filter, wherein the first light shielding layer is in contact with an end face of the second light shielding layer, and the third light shielding layer is in contact with an end face of the fourth light shielding layer. In claim 1 or claim 2,
The first light shielding layer is provided with a plurality of the first openings, a first portion positioned between two adjacent first openings, the first portion, A second portion located closer to the second light shielding layer than the plurality of first openings,
The end face of the second light shielding layer is an angle limiting filter that is located in the center of the width of the second portion of the first light shielding layer and is covered with the first light shielding layer. In any one of Claims 1 thru | or 3,
There is a gap between the first light shielding layer and the third light shielding layer, and both the first light shielding layer and the third light shielding layer are part of the fourth light shielding layer. Angle limiting filter in contact with   5. The angle limiting filter according to claim 1, wherein a reflectance of the first light shielding material is lower than a reflectance of the second light shielding material. In any one of Claims 1 to 5,
The first and third light shielding layers are angle limiting filters made of a material having a lower reflectance than aluminum. The angle limiting filter according to any one of claims 1 to 6,
A wavelength limiting filter that limits the wavelength of light that can pass through the angle limiting filter;
A light receiving element for detecting light that has passed through the angle limiting filter and the wavelength limiting filter;
A spectroscopic sensor comprising:

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