Method for manufacturing spectroscopy module, and spectroscopy module

In a spectroscopy module 1, a light detecting element 5 having a light passing hole 50 is used. Therefore, it is possible to prevent the relative positional relationship between the light passing hole 50 and a light detecting portion 5a of the light detecting element 5 from deviating. Moreover, the light detecting element 5 is electrically connected to a wiring 9 formed on a front plane 2a of a substrate 2 by face-down bonding, and a resin layer 79 is formed as an underfill resin between the substrate 2 and the light detecting element 5. Therefore, it is possible to improve the fixing strength between the substrate 2 and the light detecting element 5. Additionally, before the resin layer 79 is formed, a resin layer 78 is formed along a guide portion 77 that surrounds the passing hole 50. Thus, the resin layer 79 is prevented from penetrating into the light passing hole 50, which makes it possible to make a light be appropriately incident into the substrate 2.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for manufacturing a spectroscopy module for dispersing light to detect the light and spectroscopy module.

2. Related Background of the Invention

There is known such a conventional spectroscopy module described in, for example, Japanese Published Unexamined Patent Application No. H04-294223 (Patent Document 1), Japanese Published Unexamined Patent Application No. 2004-354176 (Patent Document 2), and Japanese Published Unexamined Patent Application No. 2003-243444 (Patent Document 3). Patent Document 1 has described a spectroscopy module which is provided with a supporting body through which light is allowed to transmit, an incident slit portion through which light is made incident into the supporting body, a concave diffraction grating that disperses the light made incident into the supporting body to reflect the light, and a diode that detects the lights dispersed and reflected by the concave diffraction grating.

SUMMARY OF THE INVENTION

However, in the spectroscopy module described in Patent Document 1, when the incident slit portion and the diode are attached to the supporting body, the relative positional relationship between the incident slit portion and the diode may deviate, thereby degrading the reliability of the spectroscopy module.

The present invention has been achieved in consideration of the above-described circumstances, and an object of the present invention is to provide a method for manufacturing a highly reliable spectroscopy module and spectroscopy module.

In order to achieve the above-described object, a method for manufacturing a spectroscopy module which is provided with a body portion through which light is allowed to transmit, a spectroscopic portion that disperses a light made incident into the body portion from a side of a predetermined plane of the body portion, and reflects lights to the side of the predetermined plane, and a light detecting element which detects the lights dispersed by the spectroscopic portion, the method includes a process of electrically connecting the light detecting element including a light passing hole through which a light advancing to the spectroscopic portion passes, and a guide portion that surrounds the light passing hole and partially leads to an outer edge of the light detecting element, to a wiring formed on the predetermined plane by face-down bonding, a process of forming a first resin layer along the guide portion between the body portion and the light detecting element, and a process of forming a second resin layer so as to make the second resin layer face a light detecting portion of the light detecting element, at an outer side of the first resin layer between the body portion and the light detecting element.

In the method for manufacturing the spectroscopy module, the light detecting element including the light passing hole through which a light advancing to the spectroscopic portion passes is used. Therefore, it is possible to prevent the relative positional relationship between the light passing hole and the light detecting portion of the light detecting element from deviating. Moreover, the light detecting element is electrically connected to the wiring formed on the predetermined plane of the body portion by face-down bonding, and the second resin layer is formed between the body portion and the light detecting element. Therefore, it is possible to improve the fixing strength between the body portion and the light detecting element, which makes it possible to prevent the electrical connection from being cut off due to the face-down bonding. Additionally, before the second resin layer is formed so as to face the light detecting portion of the light detecting element, the first resin layer is formed along the guide portion that surrounds the light passing hole of the light detecting element and partially leads to the outer edge of the light detecting element. Thus, the second resin layer is prevented from penetrating into the light passing hole by the first resin layer. Therefore, a light can be made incident into the body portion without being refracted or diffused due to a shape of the light incident side surface of the second resin layer in the light passing hole. Therefore, according to the method for manufacturing the spectroscopy module, it is possible to improve the reliability.

In the method for manufacturing the spectroscopy module according to the present invention, the second resin layer is composed of a material having an index matching property with respect to the body portion higher than that of the first resin layer. In this case, it is possible to prevent the light between the body portion and the light detecting portion of the light detecting element from being refracted.

In the method for manufacturing the spectroscopy module according to the present invention, the first resin layer is preferably composed of a material having a light absorption property higher than that of the second resin layer. In this case, it is possible to prevent the light advancing to the body portion from the light passing hole from partially becoming leakage light to be made incident into the light detecting portion of the light detecting element.

In the method for manufacturing the spectroscopy module according to the present invention, some portions of the guide portion preferably lead to respective outer edges which the guide portion faces, in the light detecting element. In this case, the first resin layer can be reliably and easily made along the guide portion.

Further, a spectroscopy module according to the present invention is manufactured by the method for manufacturing the spectroscopy module described above. In the spectroscopy module, an attempt is made to improve the reliability from the above-described reasons.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same or corresponding portions in the respective drawings are denoted by the same reference numerals, and overlapping descriptions thereof will be omitted.

FIG. 1is a plan view of a spectroscopy module as one embodiment according to the present invention, andFIG. 2is a cross sectional view taken along the line II to II shown inFIG. 1. As shown inFIG. 1andFIG. 2, a spectroscopy module1is provided with a substrate (body portion)2through which a light L1made incident from a side of a front plane (predetermined plane)2ais allowed to transmit, a lens portion (body portion)3through which the light L1made incident into the substrate2is allowed to transmit, a spectroscopic portion4that disperses the light L1made incident into the lens portion3to reflect the light toward the front plane2a, and a light detecting element5that detects lights L2dispersed by the spectroscopic portion4. The spectroscopy module1is a micro-spectroscopy module that disperses the light L1into the lights L2corresponding to a plurality of wavelengths by the spectroscopic portion4, and detects the lights L2by the light detecting element5, thereby measuring the wavelength distribution of the light L1, the intensity of a specific wavelength component, or the like.

The substrate2is formed into a rectangular plate shape (with, for example, an entire length of 15 to 20 mm, a full width of 11 to 12 mm, and a thickness of 1 to 3 mm), from light-transmitting glass such as BK7, Pyrex (registered trademark) and quartz, plastic, or the like. A wiring9composed of a single layer film of Al, Au, or the like, or a laminated film of Ti—Pt—Au, Ti—Ni—Au, Cr—Au, or the like is formed on the front plane2aof the substrate2. The wiring9has a plurality of pad portions9adisposed in the central area of the substrate2, a plurality of pad portions9bdisposed at the both ends in the longitudinal direction of the substrate2, and a plurality of connection portions9cthat connect the pad portions9aand the pad portions9bwhich correspond to one another. In addition, the wiring9has a light antireflective layer composed of a single layer film of CrO or the like, or a laminated film of Cr—CrO or the like at the side of the front plane2aof the substrate2.

Further, an insulation layer11is formed on the front plane2aof the substrate2so as to expose the pad portions9aand9bof the wiring9and also cover the connection portions9cof the wiring9. The insulation layer11has an opening portion11athrough which the light L1advancing to the spectroscopic portion4via a light passing hole50(which will be described later) of the light detecting element5passes, and the lights L2advancing to a light detecting portion5a(which will be described later) of the light detecting element5pass. Moreover, a light absorption layer67is formed on the front plane2aof the substrate2so as to expose the pad portions9aand9bof the wiring9, and also cover the insulation layer11. The light absorption layer67has a light passing hole67athrough which the light L1advancing to the spectroscopic portion4via the light passing hole50(which will be described later) of the light detecting element5passes, and a light passing hole67bthrough which the lights L2advancing to the light detecting portion5a(which will be described later) of the light detecting element5passes. As a material of the light absorption layer67, colored resin (silicon, epoxy, acryl, urethane, polyimide, composite resin, or the like) including black resist or a filler (such as carbon or oxide), metal such as Cr or Co or metal oxide thereof, or a laminated film thereof, or porous-type ceramic, metal, or metal oxide, can be cited.

FIG. 3is a bottom view of the spectroscopy module ofFIG. 1. As shown inFIGS. 2 and 3, a resist layer76having an opening portion75into which a lens portion3is fitted is formed on a rear plane2bof the substrate2. The lens portion3is formed into a shape such that a semispherical lens is cut off along two planes substantially perpendicular to its bottom plane3aand substantially parallel to each other to form its side planes3b(with, for example, a curvature radius of 6 to 10 mm, an entire length of the bottom plane3aof 12 to 18 mm, a full width of the bottom plane3a(i.e., a distance between the side planes3b) of 6 to 10 mm, and a height of 5 to 8 mm), from a material which is the same as that of the substrate2, that is light-transmitting resin, a light-transmitting organic-inorganic hybrid material, or light-transmitting low-melting point glass or plastic for replica molding, or the like. The lens portion3is fitted into the opening portion75of the resist layer76, and is bonded to the rear plane2bof the substrate2with an optical resin adhesive73through which the lights L1and L2are allowed to transmit. In addition, the lens shape is not limited to a spherical lens, and may be an aspherical lens.

The spectroscopic portion4is a reflection type grating having a diffraction layer6formed on the outer surface of the lens portion3, a reflection layer7formed on the outer surface of the diffraction layer6, and a passivation layer54that covers the diffraction layer6and the reflection layer7. The diffraction layer6is formed so that a plurality of grating grooves6aare provided adjacent to each other along the longitudinal direction of the substrate2, and the direction in which the grating grooves6aare extended is substantially matched to a direction substantially perpendicular to the longitudinal direction of the substrate2. For example, a cross-sectionally serrated blazed grating, a cross-sectionally rectangular binary grating, a cross-sectionally sinusoidal holographic grating, or the like is applied as the diffraction layer6, and the diffraction layer6is formed by subjecting optical resin for replica molding such as photo curing epoxy resin, acryl resin, or organic-inorganic hybrid resin to photo curing. The reflection layer7is a membrane form, and is formed by, for example, evaporating Al, Au, or the like onto the outer surface of the diffraction layer6. The passivation layer54is a membrane form, and is formed by, for example, evaporating MgF2, SiO2, or the like onto the outer surfaces of the diffraction layer6and the reflection layer7. In addition, an optical NA of the spectroscopy module1can be adjusted by adjusting an area on which the reflection layer7is formed.

In addition, the opening portion75of the resist layer76is formed by photo-etching so as to have a predetermined positional relationship with respect to the outer edge portion of the substrate2serving as a reference portion for positioning the light detecting element5to the substrate2. At this time, because the spectroscopic portion4is positioned with respect to the lens portion3with high precision, the spectroscopic portion4is positioned to the substrate2by merely fitting the lens portion3into the opening portion75. Meanwhile, the light detecting element5is positioned to the substrate2in accordance with the outer edge portion of the substrate2serving as a reference portion. Therefore, alignment of the spectroscopic portion4and the light detecting element5is achieved by merely fitting the lens portion3into the opening portion75.

As shown inFIGS. 1 and 2, the light detecting element5is formed into a rectangular plate shape (with, for example, an entire length of 5 to 10 mm, a full width of 1.5 to 3 mm, and a thickness of 0.1 to 0.8 mm). The light detecting portion5ais formed on the plane at the side of the spectroscopic portion4of the light detecting element5. The light detecting portion5ais a CCD image sensor, a PD array, or a CMOS image sensor or the like, and is formed so that a plurality of channels are arrayed in a direction substantially perpendicular to the direction in which the grating grooves6aof the spectroscopic portion4are extended (i.e., the direction in which the grating grooves6aare provided adjacent to each other).

In the case in which the light detecting portion5ais a CCD image sensor, light intensity information at a position at which the light is made incident into pixels disposed two-dimensionally is subjected to line-binning, and to make the information into light intensity information at a one-dimensional position, the light intensity information at the one-dimensional position is read out in time-series. That is, a line of the pixels subjected to line-binning becomes one channel. In the case in which the light detecting portion5ais a PD array or a CMOS image sensor, because light intensity information at a position at which the light is made incident into pixels disposed one-dimensionally is read out in time-series, one pixel becomes one channel.

In addition, in the case in which the light detecting portion5ais a PD array or a CMOS image sensor, and pixels are arrayed two-dimensionally, a line of pixels arrayed in a direction of a one-dimensional array parallel to the direction in which the grating grooves6aof the spectroscopic portion4are extended becomes one channel. Further, in the case in which the light detecting portion5ais a CCD image sensor, for example, a light detecting portion5ain which a space between channels in its array direction is 12.5 μm, an entire length of a channel (a length of a one-dimensional pixel row subjected to line-binning) is 1 mm, and the number of channels to be arrayed is 256 is used for the light detecting element5.

Further, the light passing hole50through which the light L1advancing to the spectroscopic portion4passes, that is provided adjacent to the light detecting portion5ain the array direction of the channels, is formed in the light detecting element5. The light passing hole50is a slit (with, for example, a length of 0.5 to 1 mm and a width of 10 to 100 μm) which is extended in a direction substantially perpendicular to the longitudinal direction of the substrate2, and is formed by etching or the like so as to be positioned with high precision with respect to the light detecting portion5a.

FIG. 4is an enlarged sectional view of a main part of the spectroscopy module ofFIG. 1. As shown inFIG. 4, the light passing hole50has a light incident side portion501that demarcates a light incident opening50athrough which the light L1is made incident, and a light emission side portion502that demarcates a light emission opening50bfrom which the light L1is emitted. The light emission side portion502is formed into a rectangular parallelepiped shape which is extended in a direction substantially perpendicular to the longitudinal direction of the substrate2, and the light incident side portion501is formed into a square pyramid shape broadening toward the opposite side from the light emission side portion502. A light blocking film57is formed on the plane opposite to the spectroscopic portion4of the light detecting element5and the inner plane of the light incident side portion501of the light passing hole50. The light blocking film57blocks the light L1that is trying to advance to the spectroscopic portion4without passing through the light passing hole50or the light L1that is trying to be directly made incident into the light detecting portion5a.

A plurality of electrodes58are provided onto the plane at the side of the spectroscopic portion4of the light detecting element5. The respective electrodes58are electrically connected to the corresponding pad portions9aby face-down bonding via bumps15in a state in which the light passing hole50faces the light passing hole67aof the light absorption layer67and the light detecting portion5afaces the light passing hole67bof the light absorption layer67. Thereby, electric signals generated in the light detecting portion5aare derived to the outside via the electrodes58, the pad portions9a, the connection portions9c, and the pad portions9b.

FIG. 5is an enlarged bottom view of a main part of a light detecting element of the spectroscopy module ofFIG. 1. As shown inFIG. 5, a guide portion77is formed as a cross-sectionally rectangular shaped groove by etching or the like in the plane at the side of the substrate2of the light detecting element5. The guide portion77has a rectangular annular surrounding portion77athat surrounds the light emission opening50bof the light passing hole50, and an extraction portion77bleading to the outer edge of the light detecting element5. In addition, the light emission opening50bis not limited to a rectangular shape, and may be, for example, a circular shape or an elliptical shape.

As shown inFIG. 4, a resin layer (first resin layer)78is formed along the guide portion77between the substrate2and the light detecting element5. The resin layer78leads to the plane on the light absorption layer67from the guide portion77, and demarcates a space through which the light passing hole50and the light passing hole67aare communicated with each other. Further, a light-transmitting resin layer (second resin layer)79is formed at the outer side of the resin layer78between the substrate2and the light detecting element5. The resin layer79faces the light detecting portion5aof the light detecting element5.

In addition, the resin layer78is composed of a material having a light absorption property with the substrate2higher than that of the resin layer79. As a material of the resin layer78, epoxy, acrylic, silicone, urethane, polyimide, or composite resin, or the like can be cited, and a filler (such as carbon or oxide) may be contained in those resins. Further, the resin layer79is composed of a material having an index matching property higher than that of the resin layer78. As a material of the resin layer79, epoxy, acryl, silicone, oil, or the like can be cited.

In the spectroscope module1configured as described above, the light L1is made incident into the substrate2from the side of the front plane2aof the substrate2via the light passing hole50of the light detecting element5and the light passing hole67aof the light absorption layer67, and advances inside the substrate2, the optical resin adhesive73, and the lens portion3, to reach the spectroscopic portion4. The light L1reaching the spectroscopic portion4is dispersed into lights L2corresponding to a plurality of wavelengths by the spectroscopic portion4. The dispersed lights L2, are not only dispersed by the spectroscopic portion4, but also reflected toward the front plane2aof the substrate2, and advance inside the lens portion3, the optical resin adhesive73, and the substrate2to reach the light detecting portion5aof the light detecting element5via the light passing hole67bof the light absorption layer67and the resin layer79. The lights L2reaching the light detecting portion5aare detected by the light detecting element5.

A method for manufacturing the spectroscopy module1described above will be described.

First, the wiring9, the insulation layer11, and the light absorption layer67are formed on the front plane2aof the substrate2, and the resist layer76having the opening portion75is formed on the rear plane2bof the substrate2. Thereafter, the light detecting element5having the light passing hole50and the guide portion77is prepared, and the electrodes58of the light detecting element5and the pad portions9aof the wiring9are electrically connected by face-down bonding via the bumps15.

Next, the resin layer78is formed along the guide portion77between the substrate2and the light detecting element5. In detail, resin is cast from the extraction portion77bleading to the outer edge of the light detecting element5, to make the resin flow around along the surrounding portion77asurrounding the light emission opening50bof the light passing hole50. Then, the resin is subjected to UV-curing or thermal-curing to be cured, to form the resin layer78.

Next, the resin layer79is formed at the outer side of the resin layer78between the substrate2and the light detecting element5, so as to face at least the light detecting portion5aof the light detecting element5. In detail, a region at the outer side of the resin layer78between the substrate2and the light detecting element5is filled with an optical resin as an underfill, and the resin is cured to form the resin layer79.

Meanwhile, the spectroscopic portion4is formed on the lens portion3. In detail, a light-transmitting master grating on which gratings corresponding to the diffraction layer6are engraved is pushed onto the optical resin for replica molding falling in drops near the tip of the lens portion3. Then, the optical resin for replica molding is subjected to light in this state to cure the optical resin for replica molding, and the optical resin for replica molding is preferably subjected to thermal curing for stabilization, to form the diffraction layer6having the plurality of grating grooves6a. Thereafter, the master grating is demolded, and Al, Au, or the like is evaporated with a mask or is entirely evaporated onto the outer surface of the diffraction layer6to form the reflection layer7. Moreover, MgF2, SiO2, or the like is evaporated with a mask or is entirely evaporated onto the outer surfaces of the diffraction layer6and the reflection layer7to form the passivation layer54.

Next, the optical resin adhesive73is applied onto the rear plane2bof the substrate2exposed in the opening portion75of the resist layer76, and the lens portion3on which the spectroscopic portion4is formed is fitted into the opening portion75, to be pressed onto the rear plane2bof the substrate2. Then, the optical resin adhesive73is subjected to light to be cured, to obtain the spectroscopy module1.

As described above, in the spectroscopy module1and the method for manufacturing the spectroscopy module, the light detecting element5having the light passing hole50through which a light advancing to the spectroscopic portion4passes, is used. Therefore, it is possible to prevent the relative positional relationship between the light passing hole50and the light detecting portion5aof the light detecting element5from deviating. Moreover, the light detecting element5is electrically connected to the wiring9formed on the front plane2aof the substrate2by face-down bonding, and the resin layer79is formed as an underfill resin between the substrate2and the light detecting element5. Therefore, the fixing strength between the substrate2and the light detecting element5is improved, which makes it possible to prevent the electrical connection from being cut off due to the face-down bonding. Additionally, before the resin layer79is formed so as to face the light detecting portion5aof the light detecting element5, the resin layer78is formed along the guide portion77that surrounds the light passing hole50of the light detecting element5and partially leads to the outer edge of the light detecting element5. Thus, the resin layer79is prevented from penetrating into the light passing hole50by the resin layer78. Therefore, a light can be made incident into the substrate2without being refracted or diffused due to a shape of the light incident side surface of the resin layer79in the light passing hole50. Therefore, according to the spectroscopy module1and the method for manufacturing the spectroscopy module1, it is possible to improve the reliability.

Further, because the resin layer79is composed of a material having an index matching property with respect to the substrate2higher than that of the resin layer78, provided that a material of the passivation film (for example, an SiO2film) at the side of the substrate2of the light detecting element5or a material having a refraction index approximate to that of a material (for example, BK7) of the substrate2is used as a material thereof, it is possible to prevent light from being refracted or reflected between the substrate2and the light detecting portion5aof the light detecting element5.

Further, because the resin layer78is composed of a material having a light absorption property higher than that of the resin layer79, it is possible to prevent a light advancing to the substrate2from the light passing hole5from partially becoming leakage light to be made incident into the light detecting portion5aof the light detecting element5.

For example, various shapes may be applied as the guide portion77. As shown inFIG. 6A, an extension portion77cextended to the opposite side of the extraction portion77bfrom the surrounding portion77amay be formed. Further, as shown inFIG. 6B, the respective extraction portions77bmay be made to lead to the outer edges which the extraction portions77brespectively face in the light detecting element5. In this case, the resin layer78can be reliably and easily made along the guide portion77.

Further, as shown inFIGS. 7A to 7C, the surrounding portion77amay be formed into an elliptic annular shape. In this case, the resin to become the resin layer78can be made to flow more smoothly along the surrounding portion77a. Further, as shown inFIGS. 7B and 7C, the surrounding portion77amay be formed double or more. Further, as shown inFIG. 7C, a plurality of extraction portions77bmay be formed so as to lead to a predetermined outer edge of the light detecting element5.

Further, as shown inFIG. 8A, the guide portion77may be intermittently formed, or as shown inFIG. 8B, the guide portion77may be formed into a concavo-convex shape in the direction of the plane at the side of the substrate2of the light detecting element5. In those cases, the resin layer78can be made easily adaptable to the guide portion77.

Further, the guide portion77may be formed into a convex shape from a permanent resist or the like. In this case, provided that a material which is the same as that of the resin layer78is used, it is possible to improve the wettability between the guide portion77and the resin layer78. In addition, provided that a filler (carbon, oxide, or the like) is contained in at least one of the guide portion77and the resin layer78, it is possible to improve the wettability between the guide portion77and the resin layer78. Moreover, the cross-sectional shapes of the guide portion77(the both thereof in the case of a groove and the case of a convex shape) are not limited to a cross-sectionally rectangular shape, but various shapes such as a cross-sectionally U-shape can be adopted.

Further, the substrate2and the lens portion3may be integrally formed with a mold, and the lens portion3and the diffraction layer6may be integrally formed of light-transmitting low-melting point glass for replica molding or the like.

In accordance with the present invention, it is possible to improve the reliability of the spectroscopy module.