JP2010098055A - Light-shielding structure, imaging apparatus, method for manufacturing the same, and biological information acquisition apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light shielding structure capable of effectively suppressing generation of noise light. <P>SOLUTION: The imaging apparatus includes a transparent substrate 30 with a plurality of lenses and a sensor substrate 10 with a plurality of pixels, corresponding to the plurality of lenses has a light-shielding structure part 20, which is disposed in between the transparent substrate 30 and the sensor substrate 10 and provided with a plurality of translucent holes 25, corresponding to the plurality of lenses, and a mortar-like inclined surface and a projection part 29 are provided on the wall surface of at least a part of the translucent holes 25 so as to reduce the reflected light of the wall surfaces 26 and 27 of the translucent holes 25 among the lights received by the pixel PX from the transparent substrate 30 through the translucent holes 25. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light shielding structure, an imaging device, and a manufacturing method thereof. Furthermore, it is related with a biometric information acquisition apparatus provided with the said imaging device.

  In recent years, with the strengthening of information security protection, the development of technology related to biometric authentication has been remarkable. Biometric authentication is a technique for identifying a certain individual from other individuals based on the determination whether the biometric information acquired from the individual to be examined is equal to biometric information registered in advance. For example, there are a method for identifying an individual based on the iris of a human pupil, a method for identifying an individual based on a vein pattern such as a human finger, and a method for identifying an individual based on a fingerprint pattern of a finger.

  In biometric authentication, there are various advantages and disadvantages depending on biometric information used for authentication. For example, biometric authentication using a vein pattern has the advantage that it is more difficult to forge authentication than biometric authentication using a fingerprint pattern. The latter has the disadvantage that it is easier to forge authentication than the former.

In order to realize highly accurate biometric authentication, it is necessary to acquire a high-quality biometric image. In this case, it is particularly important to suppress the crosstalk of incident light. In this regard, Patent Document 1 discloses a technique in which a light-shielding spacer having a plurality of openings corresponding to a lens is arranged between a lens array plate and a sensor. Patent Document 2 discloses a technique in which a light shielding layer having a plurality of openings corresponding to lenses is disposed between a microlens array and a light receiving unit.
Japanese Patent Laid-Open No. 3-157602 JP 2008-36058 A

  In order to realize highly accurate biometric authentication, a technique for reducing noise light with higher accuracy is desired.

  The present invention has been made in view of the above background, and an object thereof is to provide a light shielding structure and an imaging apparatus that can more effectively suppress the generation of noise light.

  An imaging apparatus according to the present invention is an imaging apparatus including a transparent substrate having a plurality of lenses and a sensor substrate having a plurality of pixels corresponding to the plurality of lenses, and is disposed between the transparent substrate and the sensor substrate. A light shielding structure portion having a plurality of light transmission holes corresponding to the plurality of lenses, and out of the light received from the transparent substrate through the light transmission holes and received by the pixels. In order to reduce the reflected light, at least a part of the wall surface of the light transmitting hole has a mortar-shaped inclined surface and a protrusion.

  As a result of extensive investigations by the present inventors, even if a light shielding structure is arranged between the transparent substrate and the sensor substrate and the crosstalk of incident light hits the wall surface of the light transmitting hole, a part of it is designed. It was determined that the reflected light was received by the pixel of the sensor substrate and became noise light. Here, the reflected light reaching the light receiving unit may be reflected on the wall surface a plurality of times, but in the present invention, since the light shielding member is used as the name of the light shielding structure, most of the light is reflected on the light shielding member. Absorbed. Therefore, since the reflected light attenuates, it is important to reduce the light reflected once on the wall surface and received by the light receiving unit. According to the imaging device of the present invention, since the light shielding structure portion is provided, and the wall surface of the light transmission hole is provided with the mortar-shaped inclined surface and the protrusion, the crosstalk of incident light is reflected on the wall surface of the light transmission hole. Thus, the reflected light can be reduced from being received by the pixel. Therefore, generation of noise light can be more effectively suppressed.

An image pickup apparatus manufacturing method according to the present invention is an image pickup apparatus manufacturing method including a transparent substrate having a plurality of lenses and a sensor substrate having a plurality of pixels corresponding to the plurality of lenses, wherein the light shielding structure portion is Placing on the sensor substrate;
Forming a plurality of light transmitting holes corresponding to the plurality of lenses in the light shielding structure, and the light transmitting holes have a wall surface and a protrusion having a mortar-shaped inclined surface on at least a part of the wall surface. It processes so that it may be equipped with.

  A biological information acquisition apparatus according to the present invention is a biological information acquisition apparatus that acquires biological information based on light irradiation on a subject, and includes the imaging device.

  The light blocking structure according to the present invention is a light blocking structure having a plurality of light transmitting holes, and when light enters from one of the light transmitting holes and exits from the other, is reflected on the wall surface of the light transmitting hole. In order to reduce the emitted light, at least a part of the wall surface of the light transmitting hole has a mortar-shaped inclined surface and a protrusion.

  According to the present invention, there is an excellent effect that it is possible to provide a light shielding structure and an imaging apparatus that can more effectively suppress the generation of noise light.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each embodiment is simplified for convenience of explanation. Since the drawings are simple, the technical scope of the present invention should not be interpreted narrowly based on the drawings. The drawings are only for explaining the technical matters, and do not reflect the exact sizes or the like of the elements shown in the drawings. The same elements are denoted by the same reference numerals, and redundant description is omitted. Words indicating directions such as up, down, left, and right are used on the assumption that the drawing is viewed from the front.

[First Embodiment]
The first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an explanatory diagram showing a schematic configuration of the biometric authentication device 100. FIG. 2 is a schematic cross-sectional view of the imaging apparatus. FIG. 3 is a schematic diagram illustrating a partial cross-sectional configuration of the imaging apparatus. FIG. 4 is an explanatory diagram for explaining the positional relationship between the lens and the aperture. 5 and 6 are explanatory diagrams of the light shielding structure. 7 to 10 are process diagrams showing a method for manufacturing the imaging device. FIG. 11 is an explanatory diagram showing a configuration of a mobile phone in which the biometric authentication device is incorporated. FIG. 12 is a top view of the cellular phone in a folded state. FIG. 13 is a schematic block diagram illustrating a system configuration of the biometric authentication apparatus. FIG. 14 is a flowchart for illustrating the operation of the biometric authentication apparatus.

  As illustrated in FIG. 1, the biometric authentication device 100 includes a light source 110, a controller 120, and an imaging device 150. A light source 110 and an imaging device 150 are connected to the controller 120. As will be apparent from the description below, the imaging device 150 also functions as a biological information acquisition device.

  The light source 110 is a general semiconductor optical element such as an LED (Light Emitting Diode) or an LD (Laser Diode). The light source 110 outputs near infrared rays that are absorbed by the veins 201 of the human finger 200.

  The imaging device 150 receives light transmitted through the human finger 200 and captures an image of the vein 201. Then, the imaging apparatus 150 outputs the acquired vein image (biological information) to the controller 120.

  The controller 120 is, for example, a normal computer. The controller 120 implements various functions by executing a program stored in the storage unit by the CPU. Specifically, the controller 120 drives the light source 110 to output infrared light from the light source 110. In addition, the controller 120 drives the imaging device 150 to capture an image of the vein 201 of the finger 200.

  The controller 120 also performs biometric authentication. The controller 120 calculates the degree of approximation of the biometric information acquired this time with respect to biometric information registered in advance, and determines the current authentication result based on the calculation result. The configuration and operation of the biometric authentication device 100 will be described later with reference to FIGS. 13 and 14.

  FIG. 2 shows a schematic cross-sectional configuration of the imaging device 150. As shown in FIG. 2, the imaging device 150 is formed by laminating an image sensor (sensor substrate) 10, a black sheet-shaped light shielding sheet 20 that functions as a light shielding structure, and a lens array substrate 30 in this order. The light shielding sheet 20 is patterned so as to have a light transmitting hole 25 that is a plurality of openings. An adhesive sheet (adhesive layer) 50 is disposed between the light shielding sheet 20 and the lens array substrate 30. The adhesive sheet 50 is also patterned similarly to the light shielding sheet 20. A specific configuration of the lens array substrate 30 will be described later. An optical component is formed by a laminate of the light shielding sheet 20 and the lens array substrate 30.

  As shown in FIG. 2, the light shielding sheet 20 has a two-layer structure of a first light shielding layer 21 and a second light shielding layer 22. The first light shielding layer 21 is formed with a first wall surface 26 having a mortar-shaped inclined surface that becomes a part of the wall surface of the light transmitting hole 25 and whose opening area becomes narrower as the image sensor 10 is approached. Similarly, the second light shielding layer 22 is formed with a second wall surface 27 having a mortar-shaped inclined surface that becomes a part of the wall surface of the light transmitting hole 25 and whose opening area becomes narrower as the image sensor 10 is approached. Yes. In other words, the light transmitting hole 25 is formed by the space formed by the first wall surface 26 and the second wall surface 27 formed so that the opening area becomes narrow. The first wall surface 26 and the second wall surface 27 have the same shape and size in the first embodiment. Of course, it goes without saying that the size and shape can be appropriately changed.

  As shown in FIG. 2, the joint surface between the first light shielding layer 21 and the second light shielding layer 22 has a protrusion 29 so that the second light shielding layer 22 projects beyond the first light shielding layer 21 in the light transmitting hole 25. Is formed. In other words, the bonding surface of the first light shielding layer 21 having a large opening area and the bonding surface of the second light shielding layer 22 having a small opening area are bonded to each other, and the second light shielding layer 22 is compared with the first light shielding layer 21. The protruding portion 29 of the light transmitting hole 25 is formed by protruding. For the first light shielding layer 21 and the second light shielding layer 22, it is desirable to select materials having high adhesion to each other. Thereby, it can adhere to each other without providing an adhesive layer. Of course, you may adhere the 1st light shielding layer 21 and the 2nd light shielding layer 22 through an contact bonding layer.

  Hereinafter, this will be specifically described with reference to FIG.

  The image sensor 10 is a general imaging device (CMOS (Complementary Metal Oxide Semiconductor) sensor, CCD (Charge Coupled Device) sensor, etc.). The image sensor 10 has sensitivity with respect to the emission light wavelength of the light source 110.

  The image sensor 10 includes a semiconductor substrate 11 and a wiring layer 12. The semiconductor substrate 11 is a normal silicon substrate. A plurality of pixels PX are two-dimensionally formed on the main surface (imaging surface) of the semiconductor substrate 11. The pixel PX is formed by diffusing impurities into the semiconductor substrate. In the pixel PX, an electric signal having a value corresponding to the incident light intensity is generated. The specific configuration of the semiconductor substrate 11 is arbitrary.

  The wiring layer 12 is formed by depositing an insulating layer such as a silicon oxide layer. A metal wiring functioning as a signal transmission path is embedded in the deposited insulating layer.

  A light shielding layer 12 a is embedded in the wiring layer 12. In the light shielding layer 12a, an opening OP3 is formed corresponding to each optical axis. The light shielding layer 12a forms a light shielding structure for preventing crosstalk together with other light shielding sheets 20 and the light shielding layer 33 described later.

  The light shielding layer 12a is a metal layer such as aluminum (Al). An opening OP3 corresponding to the lens 32 is formed in the light shielding layer 12a. The opening OP3 is formed by partially removing the light shielding layer 12a formed on the insulating layer. The light shielding layer 12 a is formed in the process of forming the wiring layer 12 of the image sensor 10. Therefore, the opening OP3 is positioned with high accuracy with respect to the pixel PX. Compared with the case where a light shielding layer 12 a separate from the image sensor 10 is prepared, the light shielding layer 12 a can be positioned with high accuracy with respect to the image sensor 10. It is not necessary to embed the light shielding layer 12a in the wiring layer 12, and the light shielding layer 12a may be formed on the uppermost layer of the wiring layer 12.

  The opening means an opening in an optical sense, and the opening may be filled with some substance. This also applies to the other openings OP1. The same applies to the opening OP2 of the light transmitting hole 25. The technical meaning of the opening should be interpreted broadly.

  The light shielding sheet 20 is disposed between the image sensor 10 and the lens array substrate 30 as described above. The light shielding sheet 20 according to the first embodiment is formed of a photosensitive resin. For example, a negative acrylic resin can be used. Light emitted from the light source 110 is absorbed by the light shielding sheet 20. In other words, the light shielding sheet 20 functions as an infrared absorption layer. The light shielding sheet 20 has an opening OP2 on the optical axis AX. In addition, the layer thickness of the light shielding sheet 20 is set to about 70 μm to 150 μm. From the viewpoint of protecting the image sensor 10, the light shielding sheet 20 is preferably configured by a plate-like member having elasticity and flexibility.

  The lens array substrate 30 includes a transparent substrate (first substrate) 31, a plurality of lenses 32, and a light shielding layer 33.

  The transparent substrate 31 is a plate-like member and is substantially transparent to the light emitted from the light source 110. The transparent substrate 31 is a glass plate, for example.

  The plurality of lenses 32 are two-dimensionally formed on the main surface of the transparent substrate 31. Incident light from the object side is subjected to a lens action on the lens surface of the lens 32 and travels along the optical axis AX while converging toward the pixel PX. Most of the crosstalk incident from the lens 32 adjacent to the corresponding lens 32 is absorbed by the light shielding sheet 20. However, as a result of intensive studies by the present inventors, a part of the crosstalk and a part of the light incident from the corresponding lens 32 are reflected by the wall surface of the light transmitting hole 25 and are applied to the pixels of the image sensor 10. It was found that the light was received and became noise light. The reflected light can be reduced by the light shielding sheet 20 according to the first embodiment, and the reason will be described later.

  The light shielding layer 33 has a characteristic of absorbing light emitted from the light source 110. In other words, the light shielding layer 33 functions as an infrared absorption layer. The light shielding layer 33 is, for example, a black resin. In the light shielding layer 33, a plurality of openings OP1 are formed on the optical axis AX. The opening OP1 is formed by partially removing the light shielding layer 33.

  In addition, the above-mentioned adhesive sheet 50 is a photosensitive thermosetting resin. The adhesive sheet 50 may be formed of an energy ray curable resin (for example, an ultraviolet curable resin).

  The light output from the lens 32 passes through the transparent substrate 31, the opening OP1 of the light shielding layer 33, the opening OP2 of the light shielding sheet 20, and the opening OP3 of the light shielding layer 12a in this order, and enters the pixel PX. In each pixel PX, input light is photoelectrically converted, and an electric signal having a value corresponding to the intensity of the input light is generated. The electric signal generated in each pixel PX is connected to the external bus by the reading operation of the image sensor 10.

  As shown in FIG. 4, corresponding to the lens 32, an opening OP1, an opening OP2, an opening OP3, and a pixel PX are arranged on the same axis. Corresponding to the matrix arrangement of the lenses 32, the openings OP1 to OP3 are arranged in a matrix. The opening width of each opening OP1 to OP3 is, for example, opening OP2> opening OP1 ≧ opening OP3. However, the opening OP2 is the average value of the openings of the light shielding sheet 20.

  As is apparent from the description of FIGS. 2 and 3, in this embodiment, the light shielding structure is formed by stacking three light shielding layers (the light shielding layer 33, the light shielding sheet 20, and the light shielding layer 12a) along the optical axis AX. . The light shielding sheet 20 having an intermediate light shielding layer is configured by laminating a first light shielding layer 21 and a second light shielding layer 22. The sheet thicknesses of the first light-shielding layer 21 and the second light-shielding layer 22 are secured substantially in advance in a plane. Thereby, it is possible to effectively suppress variations in the layer thickness in the plane of the light shielding layer disposed on the image sensor 10.

  Next, the reason why the light shielding structure according to the first embodiment can effectively suppress the generation of noise will be described. First, a light shielding structure according to a comparative example will be described with reference to FIG. In the light shielding sheet 20Y of FIG. 17, the light transmitting holes substantially extend in the Y-axis direction (normal direction of the main surface of the image sensor 10) in the drawing, as shown in FIG. Here, on the wall surface 26Y of the light transmitting hole 25Y, the minimum angle with respect to the X-axis direction of incident light that is reflected once and reaches the light receiving portion is defined as a °. In order to simplify the description, it is assumed that the light shielding layer 12a and the light shielding layer 33 are not present.

  Next, in the light shielding structure according to the first embodiment, consider a case where the light shielding sheet 20Y according to the comparative example of FIG. As shown in FIG. 5A, the light shielding sheet 20 is composed of a first light shielding layer 21 and a second light shielding layer 22, and the light transmitting hole 25 is composed of a first wall surface 26 and a second wall surface 27. . Here, the inclination angle of the mortar-shaped inclined surfaces of the first wall surface 26 and the second wall surface 27 with respect to the Y-axis direction is b °.

  As shown in FIG. 5A, when the light is incident on the light shielding sheet 20 at the incident angle a °, the light is reflected by the wall surface having the inclination angle b °. The reflection angle at this time is 90−a + b ° with respect to the Y-axis direction. Therefore, the reflection angle is larger than the reflection angle 90-a ° of the light shielding sheet 20Y according to the comparative example. For this reason, when the light is incident on the light shielding sheet 20 at the minimum incident angle a ° of the light shielding sheet 20Y according to the comparative example, the incident light does not reach the light receiving unit. The reflected light reaching the light receiving unit may be reflected on the wall surface a plurality of times, but since the light shielding material is used as the name of the light shielding sheet 20, most of it is absorbed on the wall surface. Therefore, since the reflected light attenuates, it is important to reduce the light reflected once on the wall surface of the light transmitting hole 25 and received by the light receiving unit.

  Next, in the light shielding structure according to the first embodiment, the minimum angle of incident light that is reflected once and reaches the light receiving unit is set to c ° as shown in FIG. The angle c at this time is larger than the angle a. In other words, the angle width of the incident light reaching the light receiving portion can be narrowed by using the light blocking structure in the first embodiment as compared with the comparative example. In addition, when it is not necessary to make the width of the angle of the incident light that reaches the light receiving portion by one-time reflection smaller than in the case of the comparative example, the opening width W2 on the image sensor 10 side is set as the opening width of the comparative example. It is possible to increase the opening width W1 on the transparent substrate 30 side. By increasing the opening diameter, it is possible to suppress the occurrence of development residue and the like and improve the yield.

  FIG. 6 is a schematic cross-sectional view of a light shielding structure according to a modification. The light shielding sheet 20a according to the figure has a three-layer structure of a first light shielding layer 21a, a second light shielding layer 22a, and a third light shielding layer 23a. The same effect can be obtained when three or more layers are stacked. In the first embodiment, the example in which the angle of inclination of the mortar-shaped inclined surface of the light shielding layer is the same between the layers has been described, but can be changed as appropriate.

  According to the light shielding structure according to the first embodiment, the crosstalk can be suppressed by providing the light shielding sheet 20 between the image sensor 10 and the transparent substrate 30. Furthermore, since the wall surface of the light transmitting hole 25 of the light shielding sheet 20 has a mortar-shaped inclined surface and further has a protrusion, the light reflected once on the wall surface of the light transmitting hole 25 and detected by the light receiving unit is effective. Can be suppressed. As a result, noise light can be reduced and a more accurate imaging device can be provided.

  Since the light-shielding sheet according to the first embodiment is laminated in advance by laminating sheets having a constant sheet thickness within a plane, it is possible to ensure uniformity in film thickness. Thereby, it is possible to suppress the occurrence of partial luminance unevenness in the acquired image due to the variation in the layer thickness of the light shielding layer in the plane. As a result, a high quality imaging device can be provided.

  Furthermore, in the first embodiment, since the number of steps such as black plating or etching is not required by adopting a black light shielding sheet, the entire structure is compared with the case where the light shielding structure is formed with a metal plate. In addition, the manufacturing process can be simplified. Further, by using a light-shielding sheet having flexibility, there is no possibility of damaging the image sensor 10 such as metal warp or protrusion.

  Of course, the material constituting the light-shielding structure is not limited to the light-shielding sheet, and may be composed of a light-shielding material including a metal plated with black plating or the like so as to have a light-shielding property. By applying the present invention, it is possible to suppress the light received by the light receiving portion by one reflection as compared with the structure according to the comparative example made of the same material. By applying the present invention, reflected light can be effectively reduced, so that choices of materials constituting the light shielding structure can be increased.

  In the first embodiment, the image sensor 10 can be mechanically protected by causing the light shielding sheet 20 to function as a protective layer of the image sensor 10.

  A method for manufacturing the lens array substrate 30 will be described with reference to FIG.

  First, as shown in FIG. 7A, the light shielding layer 33 is formed on the back surface (main surface) of the transparent substrate 31 having the lens 32 formed on the upper surface by a normal thin film forming technique (spin coating or the like). In addition, the lens 32 is shape | molded as follows, for example. The lens 32 is molded by irradiating an energy ray curable resin layer (for example, an ultraviolet curable resin) applied to the transparent substrate 31 with an intensity-modulated energy ray and removing an uncured portion of the resin layer. .

  The thickness of the light shielding layer 33 is controlled so as to be substantially constant in the plane. The thickness of the light shielding layer 33 is set to about 1 to 2 μm. In general, as the layer thickness increases, it becomes difficult to control the layer thickness. By setting the thickness of the light shielding layer 33 to be thin, it is possible to effectively prevent the thickness of the light shielding layer 33 from being varied in a plane. In addition, the quality of the image finally acquired with the image sensor 10 can be improved by preventing the dispersion | variation in the thickness of the light shielding layer 33 in a plane. For example, the occurrence of partial luminance unevenness in the acquired image can be suppressed.

  Next, as shown in FIG. 7B, the light shielding layer 33 is irradiated with exposure light through a photomask 90.

  Next, as shown in FIG. 7 (c), the portion of the developer that has not been irradiated with the exposure light is removed. The light shielding layer 33 is a negative resist. Accordingly, a portion that has been deteriorated by exposure to exposure light remains, and a portion that has not been exposed to exposure light is removed by the developer. Of course, a positive resist may be used.

  The lens array substrate 30 is manufactured by such a procedure. The opening OP1 is formed by a photolithography process including an exposure process and a development process. Therefore, the arrangement interval of the openings OP1 can be set with high accuracy. In addition, the opening width of the opening OP1 can be set uniformly in the plane. Since the thickness of the light shielding layer 33 is thin, the steps of FIGS. 7A to 7C do not take a long time.

  A method for manufacturing the imaging device 150 will be further described with reference to FIGS.

  First, as shown in FIG. 8A, a first light shielding layer 21 constituting the light shielding sheet 20 is laminated on the upper surface of a wafer (substrate) 10W. By this laminating step, the first light shielding layer 21 is disposed on the wafer 10W, and the first light shielding layer 21 is bonded to the upper surface of the wafer 10W. A plurality of image sensors (imaging devices) 10 before being diced by dicing are formed on the wafer 10W.

  The specific method of laminating is arbitrary. For example, the first light shielding layer 21 may be laminated on the wafer 10W in a state where the wafer 10W is elastically held by a pair of rolls. The roll temperature at the time of lamination is preferably set to about 100 ° C. on both the upper and lower sides.

  Next, as shown in FIG. 8B, the first light shielding layer 21 is irradiated with exposure light through a photomask 90 made of chromium or the like. As a result, the first light shielding layer 21 is altered according to the mask pattern of the photomask 90. After exposure, baking is performed to promote curing. The first light shielding layer 21 is a sheet-like photosensitive resist layer having a substantially constant layer thickness in a plane. Here, the first light shielding layer 21 is a negative acrylic resist. By forming the opening OP2 in the first light shielding layer 21 by photolithography, the opening OP2 can be positioned with respect to the pixel PX at about ± 3 μm.

  Next, as shown in FIG. 8C, the first light-shielding layer 21 is shower-washed with a developing solution (for example, 1.0 wt% sodium carbonate), and the unmodified portion of the first light-shielding layer 21 is removed. Thereby, the first light shielding layer 21 is patterned according to the mask pattern of the photomask 91. The first light shielding layer 21 is divided into portions corresponding to the plurality of image sensors 10. By forming the first light shielding layer 21 on the wafer 10W by photolithography, the opening OP2 can be positioned with high accuracy with respect to the pixel PX.

  In the photolithography process, as shown in FIG. 3, the first wall surface 26 of the first light shielding layer 21 constituting the wall surface of the light transmitting hole 25 is a mortar-shaped inclined surface whose opening area becomes narrower as it approaches the image sensor 10. The conditions are set so that. For example, in the case of a negative resist, by increasing the laminating temperature than usual or adding a post-exposure bake, the curing of the photosensitive sheet is promoted, and the opening diameter as shown in FIG. It is possible to form a hole having a wall surface having an inclined surface that becomes gradually narrower. Also, by setting the exposure amount and development to be larger than usual, it is possible to form a hole portion having a wall surface having an inclined surface such that the opening diameter gradually decreases as shown in FIG.

  Next, as shown in FIG. 8D, the second light shielding layer 22 constituting the light shielding sheet 20 is laminated on the upper surface of the first light shielding layer 21 in the same manner as described above. By this laminating step, the second light shielding layer 22 is disposed on the first light shielding layer 21, and the second light shielding layer 22 is bonded onto the wafer.

  Next, as shown in FIG. 9E, the second light shielding layer 22 is irradiated with exposure light through a photomask 91. As a result, the second light shielding layer 22 is altered according to the mask pattern of the photomask 91. Thereafter, post-exposure baking is performed in the same manner as the first light shielding layer 21. In addition, although the same thing as the above-mentioned 1st light shielding layer 21 was used for the 2nd light shielding layer 22, it is good also as a different material.

  Next, as shown in FIG. 9 (f), the second light-shielding layer 22 is shower-washed with a developer (for example, 1.0 wt% sodium carbonate), and the unmodified portion of the second light-shielding layer 22 is removed. Thereby, the second light shielding layer 22 is patterned according to the mask pattern of the photomask 91. The second light shielding layer 22 is divided into portions corresponding to the plurality of image sensors 10. By forming the second light shielding layer 22 on the wafer 10W by photolithography, the opening OP2 can be positioned with high accuracy with respect to the pixel PX.

  In the photolithography process, as shown in FIG. 3, the second wall surface 27 of the second light shielding layer 22 constituting the wall surface of the light transmitting hole 25 has a mortar-shaped inclined surface whose opening area becomes narrower as it approaches the image sensor 10. Implement to form.

  Next, as shown in FIG. 9G, the adhesive sheet 50 is laminated on the light shielding sheet 20. In addition, when laminating, the roll temperature is preferably set to about 100 ° C. By this laminating process, the adhesive sheet 50 is disposed on the light shielding sheet 20, and the two are bonded to each other. The adhesive sheet 50 is a sheet-like resin layer having adhesiveness. The adhesive sheet 50 may be formed on the light shielding sheet 20 by another thin film forming technique such as a spin coating method, without using the laminating method.

  Next, as shown in FIG. 9H, exposure light is irradiated to the adhesive sheet 50 through a photomask 91. As a result, the adhesive sheet 50 is altered according to the mask pattern of the photomask 91. The adhesive sheet 50 is a sheet-like negative resist having a substantially constant layer thickness in a plane.

  Next, as shown in FIG. 10 (i), the adhesive sheet 50 is shower-washed with a developer (for example, 1.0 wt% sodium carbonate), and the undenatured portion of the adhesive sheet 50 is removed. Thereby, the adhesive sheet 50 is patterned according to the mask pattern of the photomask 91. The adhesive sheet 50 is divided into portions corresponding to the plurality of image sensors 10.

  Next, as shown in FIG. 10 (j), a plurality of lens array substrates 30 are placed on the light shielding sheet 20 with the adhesive sheet 50 interposed therebetween, corresponding to the individual image sensors 10. In this state, these laminates are heated. Thus, the lens array substrate 30 is bonded and fixed to the light shielding sheet 20. The adhesive sheet 50 is made of a thermosetting adhesive. First, it is preferably temporarily fixed at 100 ° C. and then subjected to heat treatment at 150 ° C. for 3 hours. In this way, a laminated body of the wafer 10W, the light shielding sheet 20, and the lens array substrate 30 is formed. In addition, the arrangement position of the lens array substrate 30 may be controlled by forming an alignment mark on the wafer 10W.

  Next, as shown in FIG. 10 (k), a scribe line is formed along the dicing line (scheduled cutting line) set on the exposed surface of the wafer 10W, and a rotating blade is used along the scribe line. The wafer 10W is cut. Thereby, a plurality of imaging devices 150 can be obtained. By limiting the object to be cut to the wafer 10W, the load of the cutting process can be reduced. In addition, it is possible to suppress displacement of the openings OP1 to OP3 and the pixel PX with respect to the lens.

  As is clear from the description of FIG. 10, in the first embodiment, a plurality of lens array substrates 30 are bonded to the light shielding sheet 20 in association with each image sensor 10, and the lens array substrate 30 is attached to the light shielding sheet 20. Then, the wafer 10W is diced to obtain a plurality of imaging devices 150. By suppressing the silicon scrap generated in the dicing process from entering the opening OP2 formed in the light shielding sheet 20, it is possible to effectively suppress the deterioration of the manufacturing yield of the imaging device 150.

  As is clear from the above description, in the first embodiment, the light shielding sheet 20 is directly laminated on the semiconductor wafer 10W, and the two are bonded together. The sheet thickness of the light shielding sheet 20 is secured in advance substantially in a plane. Thereby, it is possible to effectively suppress variations in the layer thickness in the plane of the light shielding layer disposed on the image sensor 10.

  Moreover, the layer thickness of the light shielding layer 33 is set thin, and the layer thickness of the light shielding sheet 20 is set thick. Further, the opening width of the opening OP1 formed in the light shielding layer 33 is set narrow, and the opening width of the opening OP2 formed in the light shielding sheet 20 is set wide. Thereby, the light shielding sheet 20 and the entire light shielding layer 33 can realize a light shielding structure having a thick layer and a narrow opening. That is, it is possible to form a light shielding structure that has desired characteristics and can be easily manufactured.

  Further, in the first embodiment, the light shielding sheet 20 is bonded to the image sensor 10 to laminate them. In addition, the lens array substrate 30 is bonded to the light shielding sheet 20 to laminate them. By utilizing the bonding technique, the imaging device 150 can be easily manufactured, and the manufacturing of the imaging device 150 can be prevented from taking a long time.

  In this Embodiment 1, although the example which forms a light shielding structure part using a bonding technique and a lamination technique was demonstrated, it is not limited to this, In the range which does not deviate from the meaning of this invention, various manufacturing methods Can be applied. For example, instead of laminating, the first light shielding layer 21 and the second light shielding layer 22 may be laminated by spin coating.

  With reference to FIG.11 and FIG.12, the structure of the mobile telephone (electronic device) in which the biometrics apparatus 100 (imaging device 150) is integrated is demonstrated.

  FIG. 11 shows a mobile phone (mobile communication terminal) 60. The cellular phone 60 incorporates the above-described biometric authentication device (vein authentication device) 100.

  As shown in FIG. 11, the mobile phone 60 includes an upper body (first member) 61, a lower body (second member) 62, and a hinge 63. The upper main body 61 and the lower main body 62 are both plastic plate members and are connected via a hinge 63. The upper main body 61 and the lower main body 62 are configured to be freely opened and closed by a hinge 63. When the upper main body 61 and the lower main body 62 are closed, the mobile phone 60 is a flat plate member in which the upper main body 61 and the lower main body 62 are overlapped.

  The upper body 61 has a display unit 64 on the inner surface thereof. The display unit 64 displays information (name, telephone number) for identifying the called party, an address book stored in the storage unit of the mobile phone 60, and the like. A liquid crystal display device is incorporated under the display unit 64.

  The lower main body 62 has a plurality of buttons 65 on its inner surface. The operator of the mobile phone 60 operates the button 65 to open the address book, make a call, set the manner mode, and operate the mobile phone 60 as intended. The operator of the mobile phone 60 turns on or off the biometric authentication function of the biometric authentication device 100 in the mobile phone 60 based on the operation of the button 65.

  FIG. 12 shows the configuration of the front surface (upper surface) of the mobile phone 60. As shown in FIG. 12, on the front surface of the upper main body 61, a surface region R80 and a display region R90 are arranged.

  On the surface region R80, as schematically shown in FIG. 12, a human (subject) finger 200 is placed. The imaging device 150 described above is incorporated under the surface region R80. In the display area R90, characters (time, operation state, destination name, etc.) are displayed. A liquid crystal display device is incorporated under the display region R90.

  Finally, the configuration and operation of the biometric authentication device 100 will be schematically described with reference to FIGS.

  As illustrated in FIG. 13, the biometric authentication device 100 includes a processing unit 81, an authentication execution unit 82, a storage unit 84, a light source 85, and a vein image acquisition unit 86. The light source 85 corresponds to the light source 110. The vein image acquisition unit 86 corresponds to the imaging device 150.

  The biometric authentication device 100 is formed including a normal computer in which a vein image acquisition unit 86 and a light source 85 are connected to an interface. The biometric authentication device 100 should not be limited to the configuration shown in FIG.

  The biometric authentication device 100 operates as shown in FIG.

  In the initial state, the mobile phone 60 in which the biometric authentication device 100 is incorporated is in a non-operating state.

  First, the biometric authentication function of the mobile phone 60 is activated (S11). A specific method for activating the biometric authentication function is arbitrary. For example, when the operator's finger is placed on the front surface of the cover plate, the capacitance sensor is caused to output a detection signal. The output signal of the capacitance sensor is connected to the processing unit 81 via a flexible wiring. The processing unit 81 drives the light source 85 based on the detection signal from the capacitance sensor, and causes the vein image acquisition unit 86 to acquire a vein image.

  Next, image reading is executed (S12). The processing unit 81 instructs the vein image acquisition unit 86 to output an acquired image. The vein image acquisition unit 86 outputs the acquired image data to the bus based on the readout instruction from the processing unit 81.

  Next, the processing unit 81 performs image processing on the acquired image data input via the bus (S13).

  Next, the authentication execution part 82 performs authentication (S14). The authentication execution unit 82 performs biometric authentication based on the authentication image output from the processing unit 81 and the vein image image registered in advance in the storage unit 84. For example, the authentication execution unit 82 determines that the authentication is successful if the branching mode of the veins between the two images matches at N (N: a natural number of 2 or more) or more, and the branching mode of the veins matches between the two images. If there are less than N locations, authentication failure is determined (S15). The specific method of authentication depends on the image processing method, and should not be limited to the above example.

  If the authentication is successful, the function of the mobile phone in which the biometric authentication device 100 is incorporated is activated (S16). Then, the mobile phone returns to a normal operation state. Note that in the case of authentication failure, the mobile phone in which the biometric authentication device 100 is incorporated maintains a non-operating state.

  In this way, by incorporating the biometric authentication device 100 into a mobile phone, the security performance of the mobile phone is dramatically improved.

[Second Embodiment]
Next, an example of a light shielding structure different from the first embodiment will be described. In the following description, the same element members as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted as appropriate. Further, description of the same points as in the first embodiment will be omitted as appropriate, and different points will be described in detail.

  The basic configuration of the imaging apparatus according to the second embodiment is the same as that of the imaging apparatus according to the first embodiment except for the following points. That is, in the light shielding sheet 20 according to the first embodiment, the width of the light transmission hole 25 becomes narrower as it approaches the image sensor 10, whereas the light shielding structure unit according to the second embodiment transmits light as it approaches the image sensor. The difference is that the width of the hole becomes wider. Such a shape can be obtained, for example, by reducing the exposure amount than usual when a negative resist is used.

  FIG. 15 is an explanatory diagram for explaining the light shielding structure of the imaging apparatus according to the second embodiment. As shown in FIG. 15, the light shielding sheet 20b of Embodiment 2 is composed of a first light shielding layer 21b and a second light shielding layer 22b, and the light transmitting hole 25b is formed by a first wall surface 26b and a second wall surface 27b. ing. The first wall surface 26b of the first light shielding layer 21b is configured such that the width of the light transmitting hole becomes wider as it approaches the image sensor. Similarly, the second wall surface 27b of the second light shielding layer 22b is also configured so that the width of the light transmitting hole becomes wider as it approaches the image sensor.

  Here, the opening width of the light transmitting hole 25b on the main surface of the second light shielding layer 22b on the lens array substrate 30 side is defined as W1. In the first light shielding layer 21b, the opening width of the main surface on the second light shielding layer 22b side is W3, and the opening width of the main surface on the image sensor side is W4. Here, as shown in FIG. 15, it is assumed that W1> W3. Therefore, in the light transmitting hole 25b, the protruding portion 29b is formed so that the first light shielding layer 21b protrudes more than the second light shielding layer 22b. In other words, the bonding surface of the second light shielding layer 22b having a large opening area and the bonding surface of the first light shielding layer 21b having a small opening area are bonded to each other, and the first light shielding layer 21b is compared to the second light shielding layer 22b. The protrusion 29b of the light transmitting hole 25b is formed by protruding.

  In the light shielding structure according to the second embodiment, the light shielding sheet 20Y according to the comparative example of FIG. 17 is incident at the minimum angle a ° (minimum angle reflected once on the wall surface of the light transmitting hole and received by the light receiving unit). think of. As shown in FIG. 15A, the light incident at the incident angle a ° is reflected by the protrusion 29b. Thereby, the incident light does not reach the light receiving unit. Therefore, it is possible to reduce the light received by the light receiving unit by one reflection compared to the comparative example. As a result, it is possible to provide an imaging device having a light shielding structure that more effectively suppresses noise light.

  Next, consider a case where the incident angle is smaller than the incident angle a ° (here, the angle is defined as the incident angle d °). When the light enters the light shielding sheet 20b at an incident angle d °, the reflection angle becomes small because the wall surface is inclined as shown in FIG. 15B. The reflected light of the incident light is reflected by the protrusion 29b. Thereby, the incident light does not reach the light receiving unit. Therefore, it is possible to reduce the light received by the light receiving unit by one reflection compared to the comparative example. As a result, it is possible to provide an imaging device having a light shielding structure that more effectively suppresses noise light.

[Third Embodiment]
The imaging apparatus according to the third embodiment has the same basic configuration as that of the imaging apparatus according to the first embodiment except for the following points. That is, in the light shielding sheet 20 according to the first embodiment, the wall surfaces of the first light shielding layer 21 and the second light shielding layer 22 are mortar-shaped, whereas the light shielding sheet 20c according to the third embodiment is Only the first light shielding layer 21c has a mortar shape, and the second light shielding layer 22c is different in that it is a wall surface substantially parallel to the Y-axis direction.

  FIG. 16 is an explanatory diagram for explaining the light shielding structure of the imaging apparatus according to the third embodiment. As shown in FIG. 16, the light shielding sheet 20c of Embodiment 3 is composed of a first light shielding layer 21c and a second light shielding layer 22c, and the light transmitting hole 25c is formed by a first wall surface 26c and a second wall surface 27c. ing. The first wall surface 26c of the first light shielding layer 21c is configured such that the width of the light transmitting hole becomes wider as it approaches the image sensor. On the other hand, the second wall surface 27c of the second light shielding layer 22b is an opening having substantially the same width.

  Here, the opening width of the light transmitting hole 25c on the main surface of the second light shielding layer 22c on the lens array substrate 30 side is defined as W1. In the first light shielding layer 21c, the opening width of the main surface on the second light shielding layer 22c side is W4, and the opening width of the main surface on the image sensor side is W5. Here, as shown in FIG. 16, it is assumed that W1> W3. Accordingly, the projection 29c is formed in the light transmitting hole 25c so that the first light shielding layer 21c projects more than the second light shielding layer 22c. In other words, the bonding surface of the second light shielding layer 22c having a large opening area and the bonding surface of the first light shielding layer 21c having a small opening area are bonded to each other, and the first light shielding layer 21c is compared to the second light shielding layer 22c. The protrusion 29c of the light transmission hole 25c is formed by protruding.

  In the light shielding structure according to the third embodiment, consider a case where the light shielding sheet 20Y according to the comparative example of FIG. 17 is incident at the minimum angle a °. As shown in FIG. 16, when the light shielding sheet 20c is incident on the light shielding sheet 20c at an incident angle a °, the light shielding sheet 20c is reflected by the protrusion 29c, and the incident light does not reach the light receiving part. Therefore, it is possible to reduce the light received by the light receiving unit by one reflection compared to the comparative example. Therefore, it is possible to provide an imaging apparatus having a light shielding structure that more effectively suppresses noise light.

  In the above-described embodiment, an example in which a vein image is used as biological information has been described. However, the present invention can also be applied to other biological information. Further, the light shielding structure portion is not limited to that of the above-described embodiment, and any light shielding structure portion may be used as long as it has a mortar-shaped inclined surface and a protrusion on at least a part of the wall surface of the light transmitting hole. Further, the above-described light shielding structure is not limited to the imaging device, and can be applied to applications that require various light shielding structures.

It is explanatory drawing which shows schematic structure of the biometrics apparatus 100 which concerns on the 1st Embodiment of this invention. 1 is a schematic cross-sectional view of an imaging apparatus according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a partial cross-sectional configuration of an imaging apparatus according to a first embodiment of the present invention. It is explanatory drawing for demonstrating the arrangement | positioning relationship between the lens and opening which concern on the 1st Embodiment of this invention. It is explanatory drawing for demonstrating the light-shielding structure part which concerns on the 1st Embodiment of this invention. It is explanatory drawing for demonstrating the light-shielding structure which concerns on the modification of this invention. It is process drawing which shows the manufacturing method of the imaging device which concerns on the 1st Embodiment of this invention. It is process drawing which shows the manufacturing method of the imaging device which concerns on the 1st Embodiment of this invention. It is process drawing which shows the manufacturing method of the imaging device which concerns on the 1st Embodiment of this invention. It is process drawing which shows the manufacturing method of the imaging device which concerns on the 1st Embodiment of this invention. It is explanatory drawing which shows the structure of the mobile telephone with which the biometrics apparatus which concerns on the 1st Embodiment of this invention is integrated. 1 is a top view of a cellular phone in a folded state according to a first embodiment of the present invention. It is a schematic block diagram which shows the system configuration | structure of the biometrics apparatus which concerns on the 1st Embodiment of this invention. It is a flowchart for demonstrating operation | movement of the biometrics apparatus which concerns on the 1st Embodiment of this invention. It is explanatory drawing for demonstrating the light-shielding structure which concerns on the 2nd Embodiment of this invention. It is explanatory drawing for demonstrating the light-shielding structure which concerns on the 3rd Embodiment of this invention. It is explanatory drawing for demonstrating the light-shielding structure which concerns on a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image sensor 10W Wafer 11 Semiconductor substrate 12 Wiring layer 12a Light shielding layer 20 Light shielding sheet 21 1st light shielding layer 22 2nd light shielding layer 25 Translucent hole 26 1st wall surface 27 2nd wall surface 29 Projection part 30 Lens array substrate 31 Transparent substrate 32 Lens 33 Light-shielding layer 50 Adhesive sheet 60 Mobile phone 61 Upper body 62 Lower body 63 Hinge 64 Display unit 65 Button 81 Processing unit 82 Authentication execution unit 84 Storage unit 85 Light source 86 Vein image acquisition unit 150 Imaging device

Claims (13)

An imaging apparatus comprising a transparent substrate having a plurality of lenses, and a sensor substrate having a plurality of pixels corresponding to the plurality of lenses,
A light shielding structure portion disposed between the transparent substrate and the sensor substrate and having a plurality of light transmitting holes corresponding to the plurality of lenses;
A mortar-like shape is formed on at least a part of the wall of the light transmitting hole so as to reduce the reflected light of the wall of the light transmitting hole out of the light received by the pixel through the light transmitting hole from the transparent substrate. An imaging device having an inclined surface and a protrusion. The light shielding structure is composed of two or more light shielding layers,
The wall surface of at least one light shielding layer has a mortar-shaped inclined surface;
The imaging device according to claim 1, wherein the projecting portion of the light transmitting hole is formed by joining the light shielding layer surfaces having different opening areas to each other. The mortar-shaped inclined surface is formed for each light shielding layer,
The light shielding layers are arranged so that the opening areas of the light transmitting holes are narrow in the same direction,
The imaging device according to claim 2, wherein the protrusions of the light transmitting holes are stacked so that the one with the smaller opening area protrudes toward the one with the larger opening area.   The imaging device according to claim 1, wherein the light shielding structure is formed of a photosensitive resin.   The imaging device according to any one of claims 1 to 4, wherein the light shielding structure portion is formed of a laminate sheet.   The imaging device according to claim 1, wherein the light shielding structure portion has a characteristic of absorbing at least near infrared rays. A manufacturing method of an imaging device including a transparent substrate having a plurality of lenses and a sensor substrate having a plurality of pixels corresponding to the plurality of lenses,
Placing a light shielding structure on the sensor substrate;
A step of forming a plurality of light transmitting holes corresponding to the plurality of lenses in the light shielding structure portion,
The translucent hole is a method for manufacturing an imaging device, wherein the translucent hole is processed to include a wall surface having a mortar-shaped inclined surface and a protrusion on at least a part of the wall surface. The light shielding structure portion is composed of two or more light shielding layers,
Forming a wall surface having the mortar-shaped inclined surface on at least one of the light shielding layers,
The method of manufacturing an imaging apparatus according to claim 7, wherein the protrusion is formed by bonding the light shielding layers having different opening areas to each other. A mortar-shaped inclined surface constituting the light transmitting hole is formed so that an opening area is narrowed in the same direction for each light shielding layer,
The method of manufacturing an imaging apparatus according to claim 8, wherein the protrusions are stacked such that the narrower opening area protrudes toward the wider opening area. A biological information acquisition device that acquires biological information based on light irradiation on a subject,
A biological information acquisition apparatus provided with the imaging device of Claims 1-6. A light shielding structure having a plurality of light transmitting holes,
When light enters from one of the light transmitting holes and exits from the other,
A light shielding structure having a mortar-shaped inclined surface and a protrusion on at least a part of a wall surface of the light transmitting hole so as to reduce light reflected and emitted from the wall surface of the light transmitting hole. The light shielding structure is composed of two or more light shielding layers,
The wall surface of at least one light shielding layer has a mortar-shaped inclined surface;
The light shielding structure according to claim 11, wherein the protrusion of the light transmitting hole is formed by joining the light shielding layers having different opening areas. The mortar-shaped inclined surface is formed for each light shielding layer,
The wall surface having the mortar-shaped inclined surface is formed so that the opening area is narrowed in the same direction between the light shielding layers, and the projection area of the light transmitting hole has a smaller opening area. The light shielding structure according to claim 12, wherein the light shielding structure is laminated so as to protrude toward the wider side.

Images