JP2020155426A - Imaging element, electronic device, and manufacturing method of imaging element - Google Patents

Abstract

To provide a thin imaging element.SOLUTION: An imaging element includes: a light-receiving unit in which a plurality of light-receiving elements for receiving light from an object is arranged in a first direction and a second direction intersecting the first direction on a substrate; a light-emitting unit in which a plurality of light-emitting elements for emitting light between the light-receiving elements of the light-receiving unit is arranged in the second direction on the substrate; and a light guide member provided on each light-emitting element of the light-emitting unit to guide the light emitted by the light-emitting unit to the object.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image pickup device, an electronic device, and a method for manufacturing an image pickup device used for biometric authentication and the like.

An image sensor that captures a part of the body, such as a fingerprint of a finger or a palm, a palm print, a vein pattern, etc., and uses it for biometric authentication is known (see Patent Document 1).
However, in the conventional technique, there is a problem that it is difficult to reduce the thickness because a light emitting layer exists between the microlens and the light receiving element.

JP-A-2015-79856

In the image pickup device according to the first aspect of the present invention, a plurality of light receiving elements that receive light from an object are arranged in a plurality of light receiving elements on a substrate in a first direction and in a second direction intersecting the first direction. A plurality of light emitting elements that emit light between the light receiving elements of the light receiving unit and the light receiving elements are provided on the light emitting unit arranged in the second direction on the substrate and on each light emitting element of the light emitting unit. A light guide member that guides the light emitted by the light emitting unit to the object is provided.
The electronic device according to the second aspect of the present invention includes the image pickup device according to the first aspect.
The method for manufacturing an image pickup device according to the first aspect according to the third aspect of the present invention includes a step of providing a plurality of the light receiving elements in a predetermined region of the substrate and forming a wiring layer on the substrate provided with the light receiving elements. A step of exposing the upper surface of the light receiving element of the substrate after the substrate and the wiring layer are turned upside down, and a step of providing the light emitting element between the light receiving element and the light receiving element of the substrate. A step of forming a light-transmitting member on the substrate provided with the light-receiving element and the light-emitting element, and a step of forming a microlens and a light guide member on the light-transmitting member.

It is a figure which exemplifies the biometric authentication apparatus which takes a fingerprint for biometric authentication. It is a schematic diagram which shows the cross section of the image sensor according to 1st Embodiment. It is a block diagram explaining the schematic structure of an image pickup device. It is a schematic diagram which looked at the image sensor obliquely. It is a figure explaining the timing of the image pickup operation by an image sensor. 6 (a) to 6 (d) are diagrams illustrating an example of a manufacturing procedure of the image sensor. 7 (a) to 7 (d) are diagrams illustrating an example of a manufacturing procedure of the image sensor. It is a schematic diagram which shows the cross section of the image sensor according to 2nd Embodiment. It is a schematic diagram which looked at the image sensor obliquely. It is a schematic diagram which shows the cross section of the image sensor according to 3rd Embodiment.

(First Embodiment)
The image sensor according to the first embodiment of the present invention is used as an image sensor for biometric authentication in electronic devices such as automated teller machines, smartphones, and wearable devices. FIG. 1 is a diagram illustrating a biometric authentication device 10 that captures a fingerprint for biometric authentication. The biometric authentication device 10 may be incorporated into the ATM or mobile device, or may be used by connecting to the ATM or mobile device.

In FIG. 1, the cover glass 500 of the image pickup device 1 (FIG. 2), which will be described in detail later, is exposed at the position of the sensor window 20 of the biometric authentication device 10. The user touches the sensor window 20 with the finger 30 to receive fingerprint authentication. Since the biometric authentication technology is known, the description of the biometric authentication technology will be omitted, and the configuration of the image sensor 1 built in the biometric authentication device 10 will be mainly described.
Although FIG. 1 exemplifies a biometric authentication device 10 having a size suitable for fingerprint imaging, it is configured as a biometric authentication device 10 provided with an image pickup element 1 having a size suitable for each such as palm print authentication and vein pattern authentication. You can.

<Structure of image sensor 1>
FIG. 2 is a schematic view showing a cross section of an image pickup device 1 built in the biometric authentication device 10. Further, FIG. 3 is a block diagram illustrating a schematic configuration of the image pickup device 1 of FIG. In FIG. 2, the XYZ axes constituting the right-handed coordinate system orthogonal to each other are defined, and in some subsequent figures, the orientation of each figure is shown with reference to the XYZ axes in FIG. In the case of FIG. 2, the front direction of the paper surface is the X-axis plus direction, the right direction of the paper surface orthogonal to the X-axis is the Y-axis plus direction, and the direction on the paper surface orthogonal to the X-axis and the Y-axis is the Z-axis plus direction. ..

The image sensor 1 is a so-called close contact type two-dimensional image sensor. The image sensor 1 is, for example, a substrate 100 which is a semiconductor substrate of single crystal silicon, a wiring layer 200 formed on the back surface (Z-axis minus direction) thereof, and a transparent electrode formed on the front surface (Z-axis plus direction) of the substrate 100. It is composed of a transparent layer 400 formed on the surface (Z-axis plus direction) of the 300 and the transparent electrode 300, and is hermetically sealed by the cover glass 500 and the sealing body 600.

A plurality of photodiodes 101 and a plurality of light emitting elements 102 are formed on the substrate 100. As shown in FIG. 3, the plurality of photodiodes 101 are two-dimensionally arranged in the X-axis direction (row direction) and the Y-axis direction (column direction) to form the pixels of the image sensor 1.

In the example of FIG. 3, a plurality (for example, four) of the photodiode 101 are arranged and discretely arranged in the X-axis direction (row direction) of the substrate 100 (FIG. 2), and the photodiode 101 is arranged discretely. A plurality of sets (for example, four sets) of the photodiode 101 are arranged in the Y-axis direction (column direction) of the substrate 100 (FIG. 2).
Further, the light emitting element 102 is extended in a long rectangular shape in the X-axis direction (row direction) of the substrate 100, and the pair of the photodiodes 101 arranged discretely and the photodiode 101 arranged discretely. Each is placed between another set of.
The actual number of pixels of the image sensor 1 is much larger than the number shown in the figure.

Further, the semiconductor switches 103a and 103b, the row control circuit 104, the column control circuit 105, and the light emitting element control circuit 107 of FIG. 3 are formed on the same chip on the substrate 100. A known CMOS (Complementary Metal Oxide Semiconductor) image sensor is configured together with the wiring 201a to 201d formed on the wiring layer 200 (FIG. 2).

Each light emitting element 102 is connected to a light emitting element control circuit 107. This connection is made via the electrode 202 and the wiring 201c (FIG. 3) provided in the wiring layer 200 of FIG. The light emitting element 102 is controlled to be turned on and off in each X-axis direction (row direction) of the substrate 100 by the light emitting element control circuit 107.

Each pixel of the image pickup device 1 is composed of several semiconductor elements, as is referred to as a known 4-transistor or 3-transistor. To briefly explain the case of 4 transistors per pixel, each pixel has a transfer transistor that transfers the charge generated by the photodiode 101 to the floating diffusion, and a reset transistor for resetting the charge of the photodiode 101 and the floating diffusion. Includes an amplification transistor that amplifies a charge-based signal and a row-selection transistor that connects the output of the amplification transistor to the corresponding wiring 201a. In the example of FIG. 3, only the semiconductor switch 103a that functions as a row selection transistor in each pixel is shown, and the other semiconductor elements are not shown.
In the case of 3 transistors, the transfer transistor among the above 4 transistors is omitted.

The wiring 201d corresponds to a horizontal read signal line connected to the output terminal 108. The wiring 201a of each row corresponding to the vertical readout signal line is connected to the wiring 201d via a semiconductor switch 103b that functions as a column selection transistor.

The transparent electrode 300 formed on the surface (Z-axis plus direction) of the substrate 100 of FIG. 2 is formed of, for example, indium tin oxide (ITO) and functions as a common electrode of the light emitting element 102. Further, in the wiring layer 200, individual electrodes 202 are formed for each light emitting element 102. The light emitting element control circuit 107 (FIG. 3) described above controls the light emission of each light emitting element 102 via the corresponding individual electrodes 202.

A transparent layer 400 is formed on the upper surface (Z-axis plus direction) of the transparent electrode 300. The transparent layer 400 is formed of, for example, a transparent resin. In the present embodiment, the microlens 401 and the slope 402 are formed by processing the shape of the transparent layer 400.

A microlens 401 is formed on the transparent layer 400 at a position above each photodiode 101. The microlens 401 forms a real image of an object (fingerprint of a finger 30 in the example of FIG. 1) located on the upper surface (Z-axis plus direction) of the cover glass 500 on the light receiving surface of the photodiode 101. That is, the shape and refractive index of the microlens 401 are adjusted so that the real image of the contact surface of the object in contact with the upper surface of the cover glass 500 is formed on the light receiving surface of the photodiode 101. With this configuration, the light from each part of the contact surface of the object in contact with the cover glass 500 is appropriately collected and received by the corresponding photodiode 101. In other words, each photodiode 101 receives light from a portion of an object in contact with the cover glass 500 above each photodiode 101 (Z-axis plus direction).

Further, the transparent layer 400 above the light emitting element 102 of FIG. 2 is provided with a slope 402. As the light rays output from the light emitting element 102 are refracted on the slope 402, the portion of the cover glass 500 on the photodiode 101 arranged next to the light emitting element 102 is illuminated by the light emitting element 102. That is, the inclination angle and the refractive index of the slope 402 are adjusted so as to illuminate the portion of the cover glass 500 on the photodiode 101 arranged next to the light emitting element 102.
As described above, the image sensor 1 described above is airtightly sealed by the sealing body 600 and the cover glass 500 by a known method.

FIG. 4 is a schematic view of the image sensor 1 viewed obliquely. FIG. 4 mainly illustrates the configuration of the transparent layer 400, and the cover glass 500 and the sealing body 600 of FIG. 2 are omitted. According to FIG. 4, among the transparent layers 400 provided on the upper surface (Z-axis plus direction) of the substrate 100, a plurality of microlenses are located at positions above the plurality of photodiodes 101 (FIG. 2) constituting the pixels. 401 is formed. Further, a slope 402 is formed between the rows of the plurality of microlenses 401.

The slope 402 is inclined so that the height in the Z-axis direction becomes lower toward the minus direction of the Y-axis. The slope 402 directs the light from the light emitting element 102 (FIG. 2) to the cover glass 500 (FIG. 2) above the photodiode 101 (FIG. 2) located next to the light emitting element 102. That is, the slope 402 bends the light rays output from the light emitting element 102 (FIG. 2) and traveling in the positive direction of the Z axis toward the photodiode 101 (FIG. 2) arranged next to the light emitting element 102.

<Operation of image sensor 1>
Next, the operation of the image sensor 1 will be briefly described. As described above, the object to be imaged (fingerprint of the finger 30 in the example of FIG. 1) comes into contact with the upper surface (Z-axis plus direction) of the cover glass 500. Since the region of the cover glass 500 in contact with the object is shielded from light, the amount of light incident on the light receiving surface of the photodiode 101 from the outside of the image sensor 1 through the cover glass 500 is reduced.

The image sensor 1 is configured to start an image pickup operation when, for example, the amount of light received by the plurality of photodiodes 101 becomes lower than a predetermined value. When the imaging operation is started, the light emitting element control circuit 107 (FIG. 3) first causes the plurality of light emitting elements 102 to emit light in sequence. The light emitted by each light emitting element 102 is refracted by the slope 402 (FIG. 2) above each light emitting element 102, and the cover glass 500 on a plurality of photodiodes 101 arranged in a row next to each light emitting element 102. Illuminates the part of the object located on the upper surface (Z-axis plus direction) of.

The light reflected by the illuminated portion of the object passes through the cover glass 500 and enters the image sensor 1 again. The light that has entered the image sensor 1 is received by the photodiode 101 under the microlens 401 via the microlens 401, respectively. In this way, the image sensor 1 captures a real image of the same size as the object to be imaged that comes into contact with the upper surface of the cover glass 500.

<Image capture timing operation>
FIG. 5 is a diagram illustrating the timing of the image pickup operation by the image pickup device 1. Since the image sensor 1 is a CMOS image sensor, an exposure operation and a read operation are performed for each row (arrangement in the X-axis direction in FIG. 3) of the photodiode 101 constituting the pixel.

The timing chart of FIG. 5 shows the operation of the photodiode 101 on the nth row and the n + 1th row and the light emitting element 102 corresponding to the nth row and the n + 1th row. First, the row control circuit 104 (FIG. 3) supplies a row selection pulse for the nth row to the row selection transistor (semiconductor switch 103a) via the wiring 201b to turn on the row selection transistor (semiconductor switch 103a). Then, at time t0n, the row control circuit 104 (FIG. 3) supplies a reset pulse RSTn for each photodiode 101 in the nth row to a reset transistor (not shown) via the wiring 201b. This turns on the reset transistor and resets the charge stored in each photodiode 101 on line n and the corresponding floating diffusion.

At the same time, at time t0n, the light emitting element control circuit 107 (FIG. 3) sets the light emitting element control signal ILLn for the light emitting element 102 on the nth line to the H level via the wiring 201c. As a result, the light emitting element 102 on the nth row is turned on. As a result, the illumination light from the light emitting element 102 in the nth row is refracted by the slope 402 of the transparent layer 400 (FIG. 2) described above, and the portion of the object on the cover glass 500 on the photodiode 101 in the nth row is formed. Illuminate. The light reflected by the illuminated portion of the object is incident on the photodiode 101 via the microlens 401.

Next, at time t1n, the row control circuit 104 (FIG. 3) supplies a transfer pulse TRn for the pixel in the nth row to a transfer transistor (not shown) via the wiring 201b. As a result, the charges generated by each photodiode 101 by the incident light are transferred to the corresponding floating diffusion.

At the same time, at time t1n, the light emitting element control circuit 107 sets the light emitting element control signal ILLn for the light emitting element 102 on the nth line to the L level via the wiring 201c. As a result, the light emitting element 102 on the nth row is turned off. The time Tn from the time t0n when the light emitting element 102 on the nth line is lit to the time t1n is the exposure time of the photodiode 101 on the nth line. That is, the exposure time of the photodiode 101 on the nth row can be controlled by controlling the lighting time of the light emitting element 102 on the nth row.

When the transfer of electric charge from the photodiode 101 in the nth row is completed, the column control circuit 105 (FIG. 3) sequentially supplies the read pulse ROn to the semiconductor switch 103b (column selection transistor) in each column at time t2n. As a result, the amplification signal based on the electric charge transferred to the floating diffusion in the nth row is sequentially read from the output terminal 108 via the wiring 201a and the wiring 201d in the column selected by the semiconductor switch 103b. As a result, the exposure operation and the read operation in the plurality of photodiodes 101 constituting the pixel in the nth row are completed.

In the same manner as in the nth line, the exposure operation and the reading operation are performed in the n + 1th line as well. The same procedure is repeated below, and the image information of the object is obtained by performing the exposure operation and the read operation for all the rows of the image sensor 1.

As a characteristic of the CMOS image sensor, the reading of the next line cannot be started until the reading of one line is completed. Therefore, the supply of the row selection pulse for the n + 1th row, the supply of the reset pulse RSTn + 1, the supply of the transfer pulse TRn + 1, and the control timing of the light emitting element control signal ILLn + 1 for the light emitting element 102 are also shifted backward by the read time by the read pulse ROn. Become a thing. Subsequent reads are also sequentially shifted, so-called rolling reads.

The exposure time Tn + 1 may be basically the same as Tn, but it may be changed for each row in consideration of variations in the characteristics of the light emitting element 102 and the like.

<Manufacturing method>
An example of the manufacturing procedure of the image sensor 1 will be described with reference to FIGS. 6 and 7. In FIG. 6A, peripheral elements such as a photodiode 101, a floating diffusion, and a transistor that form each pixel are formed at a predetermined position on a silicon substrate 100, for example, by using a known method.
In addition, in FIG. 6 and FIG. 7, the illustration of the floating diffusion, the transistor, etc. is omitted.

In FIG. 6B, the wiring layer 200 is formed on the silicon substrate 100 by a known method. The wiring layer 200 is formed with multiple layers of wirings 201a, 201b, 201c, and 201d for inputting / outputting a control signal for driving the image sensor 1 and a signal generated by the image sensor 1. At this time, the electrode 202 for the light emitting element 102, which will be described later, is formed in the lowermost layer of the wiring layer 200.
Note that in FIGS. 6 and 7, the wiring 201c and 201d are not shown.

In FIG. 6C, the silicon substrate 100 is turned upside down. By reversing the upper limit, the electrode 202 is located on the upper layer of the wiring layer 200. In FIG. 6D, the silicon substrate 100 is scraped from the upper surface of the silicon substrate 100 by a method such as chemical etching until the light receiving surface of the photodiode 101 appears on the surface.

In FIG. 7A, the region of the silicon substrate 100 corresponding to the electrode 202 for the light emitting element 102 is selectively removed by using a technique such as photolithography to expose the light emitting electrode 202.

In FIG. 7B, the light emitting element 102 is formed in the region from which the silicon substrate 100 has been removed. Since the electrode 202 is provided in advance, the post-process can be simplified. The light emitting element 102 is, for example, a light emitting diode (LED) using a compound semiconductor, an organic EL (electroluminescence), or the like. As a method for forming the light emitting element 102, crystal growth, vapor deposition, sputtering, printing or the like using photolithography can be appropriately used.

According to FIG. 7B, since the photodiode 101 and the light emitting element 102 can be formed on substantially the same plane, the image sensor 1 is made thinner than the case where the light emitting layer is laminated on the photodiode 101, for example. Can be configured.

Next, as shown in FIG. 7C, a transparent electrode 300 is formed on the silicon substrate 100 and the light emitting element 102. As the transparent electrode 300, indium tin oxide (ITO) or the like is used as described above. As described above, in the present embodiment, the transparent electrode 300 is used as a common electrode of the light emitting element 102.

Then, as shown in FIG. 7D, the transparent layer 400 is formed on the transparent electrode 300. Further, in the transparent layer 400, a microlens 401 is formed on each of a plurality of photodiodes 101 constituting a pixel. Further, a slope 402 is formed on the light emitting element 102. The method of forming the microlens 401 or the slope 402 may be a method of forming the transparent layer 400 and then molding by embossing, or a method of adhering the transparent layer 400 previously molded by casting polymerization or the like to the upper surface of the transparent electrode 300. It may be.

According to the first embodiment described above, the following effects can be obtained.
(1) In the image pickup element 1, the photodiode 101 that receives light from an object to be imaged (finger 30 in the above example) has an X-axis direction (row direction) and a Y-axis direction (column direction) on the substrate 100. A plurality of light receiving portions (general term for a plurality of photodiodes 101) arranged in each of the light receiving portions and a light emitting element 102 that emits light between the photodiode 101 and the photodiode 101 of the light receiving portions are arranged in the Y-axis direction on the substrate 100 (general term). It includes a plurality of light emitting units (general term for a plurality of light emitting elements 102) arranged in a row direction), and a slope 402 provided on each light emitting element 102 of the light emitting unit and guiding light from the light emitting unit to an object.
By arranging the light receiving unit and the light emitting unit on the same substrate 100, the image sensor 1 can be made thinner than the case where the light receiving unit and the light emitting unit are laminated. Further, since the light emitted by the light emitting element 102 of the light emitting unit is guided to the finger 30 by the slope 402, the finger 30 can be appropriately illuminated and the light reflected by the finger 30 can be received by the photodiode 101 of the light receiving unit. it can. With this configuration, the image sensor 1 can appropriately image the image of the finger 30 (fingerprint).

(2) In the image sensor 1 of the above (1), each light emitting element 102 of the light emitting portion is extended in a long rectangular shape in the X axis direction (row direction) on the substrate 100, and is extended in the X axis direction (row direction) of the light receiving portion. The plurality of photodiodes 101 arranged in the direction) and the light emitting elements 102 of the light emitting unit were alternately arranged in the Y-axis direction (row direction) on the substrate 100.
Since the light emitting element 102 of the light emitting unit is formed in a rectangular shape long in the X-axis direction (row direction) on the substrate 100, the light emitting unit can be divided into rows to control lighting and extinguishing. With this configuration, for example, the light emitting elements 102 can be turned on in order at the timing of imaging by a plurality of photodiodes 101 arranged in the X-axis direction (row direction) of the light receiving unit.

(3) In the image pickup device 1 according to the above (1) or (2), the slope 402 bends the light emitted by the light emitting element 102 toward the photodiode 101 arranged next to the light emitting device 102. With this configuration, the photodiode 101, which is arranged in the X-axis direction (row direction) next to the light emitting element 102 among the photodiodes 101 of the light receiving unit, emits the light emitted by the light emitting element 102 of the light emitting unit. It can be appropriately guided to the finger 30 to be imaged.

(4) In the image sensor 1 of the above (1) to (3), since each photodiode 101 of the light receiving portion receives the light reflected by the different parts of the finger 30, the image sensor 1 is the finger 30 (fingerprint). ) Can be properly imaged.

(5) In the image sensor 1 of the above (4), since the microlens 401 provided in each photodiode 101 of the light receiving portion and condensing the reflected light of the object on the photodiode 101 is provided, the microlens 401 is not provided. It is possible to take a bright and high-quality image as compared with the above.

(6) In the image sensor 1 of the above (5), the transparent layer 400 is provided on the upper surfaces of the light receiving portion and the light emitting portion, and the slope 402 and the microlens 401 are formed on the transparent layer 400. Compared with the case where the slope 402 and the microlens 401 are made of different materials, the manufacturing becomes easier and the manufacturing cost can be reduced.

(7) In the image sensor 1 of the above (6), the light receiving unit captures an image of the same size of an object in contact with the cover glass 500 provided on the object side of the transparent layer 400. With this configuration, it is possible to obtain an image sensor 1 suitable for biometric authentication such as fingerprints.

(8) The method for manufacturing the image sensor 1 includes a step of providing a plurality of photodiodes 101 in a predetermined region of the substrate 100, a step of forming a wiring layer 200 on the substrate 100 provided with the photodiode 101, and a substrate 100 and a wiring layer. An etching step of exposing the upper surface of the photodiode 101 of the substrate 100 after turning the 200 upside down, a step of providing a light emitting element 102 between the photodiode 101 of the substrate 100 and the photodiode 101, and the photodiode 101 and the light emitting element 102. The step of forming the light-transmitting member 400 on the substrate 100 provided with the above, and the step of forming the microlens 401 and the slope 402 on the light-transmitting member 400 are included.
Since the light receiving portion and the light emitting portion can be arranged on the same substrate 100 because of such a configuration, it is possible to manufacture an image sensor 1 thinner than the case where the light receiving portion and the light emitting portion are laminated.

(9) In the manufacturing method of (8) above, in the step of forming the wiring layer 200, the wiring layer 200 including the electrode 202 in the lowermost layer between the photodiode 101 and the photodiode 101 of the substrate 100 is placed on the substrate 100. In the step of providing the light emitting element 102, the light emitting element 102 is provided on the electrode 202 of the substrate 100, respectively. Since it is configured in this way, it is easier to manufacture and the manufacturing cost can be reduced as compared with the case where the electrode 202 is provided later.

(Second Embodiment)
Instead of the slope 402 formed on the transparent layer 400 of the image pickup device 1 according to the first embodiment, a prism group 403 composed of a plurality of striped prisms may be formed on the transparent layer 400. FIG. 8 is a schematic view showing a cross section of the image pickup device 1A according to the second embodiment.

FIG. 9 is a schematic view of the image sensor 1A of FIG. 8 as viewed obliquely. In FIG. 9, the cover glass 500 and the sealing body 600 of FIG. 2 are omitted. Further, as in the case of FIG. 4, among the transparent layers 400 provided on the upper surface (Z-axis plus direction) of the substrate 100, the positions above the plurality of photodiodes 101 (FIG. 8) constituting the pixels are respectively. A plurality of microlenses 401 are formed.

The prism group 403 formed on the transparent layer 400 has a saw-like cross section like a linear Fresnel lens by forming a plurality of linear grooves parallel to the X-axis. In other words, the prism group 403 is composed of a plurality of prisms extending long in the X-axis direction.

In FIG. 8, the light rays output from the light emitting element 102 are refracted by the prism group 403, so that the portion of the cover glass 500 on the photodiode 101 arranged next to the light emitting element 102 is illuminated by the light emitting element 102. Will be done. That is, the angles and refractive indexes of the plurality of prisms constituting the prism group 403 are adjusted so as to illuminate the portion of the cover glass 500 on the photodiode 101 arranged next to the light emitting element 102.

The light reflected by the illuminated portion of the object passes through the cover glass 500 and enters the image sensor 1A again. The light that has entered the image sensor 1A is received by the photodiode 101 under the microlens 401 via the microlens 401, respectively. In this way, the real image of the object to be imaged that comes into contact with the upper surface of the cover glass 500 is imaged by the image sensor 1A.

According to the second embodiment, the same action and effect as those of the first embodiment can be obtained.
In particular, in the image sensor 1A, the prism group 403 bends the light emitted by the light emitting element 102 toward the photodiode 101 arranged next to the light emitting element 102. With this configuration, the photodiode 101, which is arranged in the X-axis direction (row direction) next to the light emitting element 102 among the photodiodes 101 of the light receiving unit, emits the light emitted by the light emitting element 102 of the light emitting unit. It can be appropriately guided to the finger 30 to be imaged.

As a modification of the second embodiment, instead of providing the prism group 403, the refractive index of the transparent layer 400 may be gradually changed according to the position in the Y-axis direction of FIG. .. By gradually changing the refractive index of the transparent layer 400 according to the position in the Y-axis direction, the light rays output from the light emitting element 102 are refracted by the transparent layer 400. The refractive index of the transparent layer 400 at a position in the Y-axis direction is adjusted so as to illuminate a portion of the cover glass 500 on the photodiode 101 arranged next to the light emitting element 102.
With this configuration as well, the portion of the cover glass 500 on the photodiode 101 arranged next to the light emitting element 102 can be appropriately illuminated by the light emitting element 102.

(Third Embodiment)
FIG. 10 is a schematic view showing a cross section of the image pickup device 1B according to the third embodiment. The difference from the image sensor 1 according to the first embodiment is that the space between the transparent layer 400 and the cover glass 500 is filled with a transparent substance 450 such as resin, and a strip-shaped reflection extending long in the X-axis direction therein. The surface 451 and the semitransparent surface 452 were formed. That is, the reflecting surface 451 and the semitransparent surface 452 have a shape in which the direction perpendicular to the paper surface of FIG. 10 is the longitudinal direction.

In FIG. 10, the refractive index of the transparent substance 450 is set lower than the refractive index of the transparent layer 400. The light rays output from the light emitting element 102 are reflected by the reflecting surface 451 and further reflected by the semitransparent surface 452 to illuminate the portion of the object located on the upper surface (Z-axis plus direction) of the cover glass 500.

The light reflected by the illuminated portion of the object passes through the cover glass 500 and enters the image sensor 1B again. The light that has entered the image sensor 1B is received by the photodiode 101 under the microlens 401 via the semitransparent mirror 452 and the microlens 401, respectively. In this way, the real image of the object to be imaged that comes into contact with the upper surface of the cover glass 500 is imaged by the image sensor 1B.

As a method for forming the reflective surface 451 and the semitransparent mirror surface 452 in the image pickup device 1B, for example, there is a method in which a thin substrate previously formed by a method such as thin film deposition or plating is insert-molded into a transparent substance 450.

Alternatively, the transparent substance 450 is cut diagonally to expose the surface on which the reflective surface 451 and the semitransparent surface 452 should be formed, and the reflective surface 451 and the semitransparent surface 452 are formed on the exposed surface by a method such as thin film deposition. , The transparent substance 450 may be adhered again on the cut surface.

As described above, according to the third embodiment, the same action and effect as those of the first embodiment can be obtained.
In particular, in the image pickup device 1B, the reflection surface 451 and the semitransparent mirror surface 452 bend the light emitted by the light emitting element 102 toward the photodiode 101 arranged next to the light emitting element 102. With this configuration, the photodiode 101, which is arranged in the X-axis direction (row direction) next to the light emitting element 102 among the photodiodes 101 of the light receiving unit, emits the light emitted by the light emitting element 102 of the light emitting unit. It can be appropriately guided to the finger 30 to be imaged.

The following modifications are also within the scope of the present invention, and one or more of the modifications can be combined with the above-described embodiment.
(Modification example 1)
In each of the above-described embodiments, one light emitting element 102 arranged between rows in which a plurality of photodiodes 101 are arranged in the X-axis direction and extending in a long rectangular shape in the X-axis direction causes the light emitting element 102. The portion of the cover glass 500 above the plurality of photodiodes 101 arranged in one row next to was illuminated. The line where the light emitting element 102 and the photodiode 101 are lined up does not necessarily have to have a one-to-one correspondence. For example, one light emitting element 102 extending in the X-axis direction may illuminate a portion of the cover glass 500 on a plurality of photodiodes 101 arranged in a plurality of rows adjacent to the light emitting element 102.

(Modification 2)
Further, contrary to the first modification, a plurality of light emitting elements 102 extending in a long rectangular shape in the X-axis direction are arranged between rows where a plurality of photodiodes 101 are arranged in the X-axis direction. The light emitting element 102 of the above may illuminate a portion of the cover glass 500 on a plurality of photodiodes 101 arranged in one row next to the light emitting element 102.

(Modification 3)
Furthermore, instead of the light emitting element 102 extending in the X-axis direction in a rectangular shape, a plurality of light emitting elements arranged in the X-axis direction may be referred to as a light emitting element 102. That is, a plurality of light emitting elements are arranged in the X-axis direction between the rows in which the plurality of photodiodes 101 are arranged in the X-axis direction to form the light emitting element 102.

It is not always necessary that one light emitting element constituting the light emitting element 102 of the third modification 3 and one photodiode 101 have a one-to-one correspondence. For example, one light emitting element constituting the light emitting element 102 may illuminate a portion of the cover glass 500 on two photodiodes 101 arranged in one row next to the light emitting element 102. The two light emitting elements constituting the light emitting element may illuminate a portion of the cover glass 500 on one photodiode 101 arranged in one row next to the light emitting element 102.

One of the measures to reduce the burden of lighting control of the light emitting element 102 by the light emitting element control circuit 107 is to increase the number of light emitting elements constituting the light emitting element 102 that are simultaneously turned on and turned off at the same time. is there. In an extreme example, when all the light emitting elements 102 provided in the image sensor 1 are turned on at the same time and all the light emitting elements 102 are turned off at the same time, the light emitting elements 102 are individually turned on at different timings and turned off, as compared with the case where they are turned off. The burden of lighting control on the light emitting element 102 can be reduced.

(Modification example 4)
In the substrate 100 of the image sensor 1 (1A, 1B) described above, a partition wall is provided between a plurality of photodiodes 101 arranged in the X-axis direction and one light emitting element 102 extending in a rectangular shape extending in the X-axis direction. May be provided. By providing the partition wall, it is possible to prevent light leakage from the light emitting element 102 to the photodiode 101 on the substrate 100.

(Modification 5)
When the vein pattern is imaged by the biometric authentication device 10, it is preferable to provide the transparent layer 400 with an interference film filter for transmitting near-infrared light. The reason for this is to make it easier to obtain image information by near-infrared light by utilizing the property that infrared rays penetrate the skin more easily than visible light and the property that reduced hemoglobin in blood absorbs near-infrared light. is there.

(Modification 6)
In the above description, the example in which the image sensor 1 is used for the biometric authentication device 10 has been described, but the image sensor 1 may be used for a device that captures a QR code (registered trademark). Further, the image sensor 1 may be used in a scanner device that captures a part of a banknote, for example, for determining the authenticity of the banknote.

Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other aspects considered within the scope of the technical idea of the present invention are also included within the scope of the present invention.

1, 1A, 1B ... Image sensor 30 ... Finger (object)
100 ... Substrate 101 ... Photodiode 102 ... Light emitting element 200 ... Wiring layer 202 ... Electrode 300 ... Transparent electrode 400 ... Transparent layer 401 ... Microlens 402 ... Slope 403 ... Prism group 500 ... Cover glass

Claims (12)

A light receiving unit in which a plurality of light receiving elements for receiving light from an object are arranged in a first direction on the substrate and in a second direction intersecting the first direction, respectively.
A plurality of light emitting elements that emit light between the light receiving elements of the light receiving unit and the light receiving elements are arranged on the substrate in the second direction.
A light guide member provided on each light emitting element of the light emitting unit and guiding the light from the light emitting unit to the object.
An image sensor comprising. In the image pickup device according to claim 1,
Each light emitting element of the light emitting unit is extended in the first direction on the substrate.
An image pickup device in which a plurality of light receiving elements arranged in the first direction of the light receiving unit and light emitting elements of the light emitting unit are alternately arranged in the second direction on the substrate. In the image pickup device according to claim 1 or 2.
The light guide member is an image pickup element that bends the light emitted by the light emitting element toward the light receiving element arranged next to the light emitting element. The image sensor according to any one of claims 1 to 3.
Each light receiving element of the light receiving unit is an image sensor that receives light reflected by different parts of the object. In the image pickup device according to claim 4,
An image pickup device provided on each light receiving element of the light receiving unit and comprising a microlens that collects the reflected light of the object on the light receiving element. In the image pickup device according to claim 5,
A transparent layer is provided on the upper surface of the light receiving portion and the light emitting portion.
The light guide member and the microlens are image pickup devices formed on the transparent layer. In the image pickup device according to claim 6,
The light receiving unit is an image pickup device that captures an image of the same size of the object in contact with the cover glass provided on the object side of the transparent layer. A line-shaped light emitting part in which a light emitting element that irradiates an object is provided on the first line of the substrate, and
A plurality of light receiving elements in which light receiving elements that receive light from the object are discretely provided on a second line different from the first line of the substrate, and
A light guide member provided on the light emitting element and guiding the light from the light emitting unit to the object.
An image sensor comprising. The image pickup device according to claim 8, further comprising a plurality of light receiving units each provided on the plurality of light receiving units and condensing light from the object on the light receiving element. An electronic device comprising the image pickup device according to any one of claims 1 to 9. The method for manufacturing an image sensor according to any one of claims 1 to 9.
A step of providing a plurality of the light receiving elements in a predetermined area of the substrate, and
A step of forming a wiring layer on the substrate provided with the light receiving element, and
A step of exposing the upper surface of the light receiving element of the substrate after the substrate and the wiring layer are turned upside down.
A step of providing the light emitting element between the light receiving element and the light receiving element of the substrate,
A step of forming a translucent member on the substrate provided with the light receiving element and the light emitting element, and
A step of forming a microlens and a light guide member on the translucent member, and
A method for manufacturing an image sensor including. In the method for manufacturing an image sensor according to claim 11,
In the step of forming the wiring layer, a wiring layer including an electrode in the lowermost layer between the light receiving element and the light receiving element of the substrate is formed on the substrate as the wiring layer.
The step of providing the light emitting element is a method of manufacturing an image pickup device in which the light emitting element is provided on the electrodes of the substrate.

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