JP2014239183A - Photoelectric conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve resolution while suppressing deteriorated sensitivity in a photoelectric conversion device for reading an image by scanning a subject relatively to a predetermined direction.SOLUTION: The photoelectric conversion device for reading the subject by scanning the subject relatively to a first direction includes: a plurality of photoelectric conversion arrays disposed along the first direction; a plurality of photoelectric conversion units, disposed along a second direction, constituting the photoelectric conversion arrays; each micro lens disposed corresponding to each photoelectric conversion unit; and a light shield unit having a light receiving window between each micro lens and each photoelectric conversion unit. The width of the micro lens in the first direction is larger than the width in the second direction, and the width of the light receiving window in the first direction is larger than the width in the second direction.

Description

  The present invention relates to a photoelectric conversion device used for a copying machine, a scanner, or the like.

  2. Description of the Related Art As photoelectric conversion devices, image sensors having a vertical register corresponding to a vertical column of light receiving elements in a pixel and a horizontal register on the transfer destination side of each vertical register are widely used. In such an image sensor, in order to improve the sensitivity by increasing the amount of light incident on the photodiode, a technique is known in which a microlens is formed on each photodiode to collect light on the pixel. In addition, a technique is known in which a light receiving window on each pixel is formed in a rectangular shape when viewed from a direction perpendicular to the light receiving surface of a photodiode (for example, Patent Document 1). The reason why the pixel having the rectangular shape disclosed in Patent Document 1 is used is as follows.

  In the case of the NTSC system, which is a standard television system, an effective combination of the horizontal resolution (number of samples) and the number of lines in the vertical direction within the effective display screen is 720 pixels horizontal × 480 lines vertical. There are many. Since this is displayed on the screen of a standard television receiver with a horizontal: vertical ratio of 4: 3, the shape of one pixel of the CCD image sensor is a vertically long ratio of horizontal: vertical of about 8: 9. It becomes a rectangle.

JP 2000-174244 A

  However, Patent Document 1 describes how to provide a microlens and a light receiving window on each photodiode in a configuration in which an image is acquired by scanning a photoelectric conversion device, such as used in a copying machine or a scanner. Is not disclosed at all.

  In a copying machine or a scanner, a photoelectric conversion device having a plurality of photoelectric conversion arrays for detecting each color such as red (R), green (G), and blue (B) is used. Each photoelectric conversion array is arranged at a predetermined interval in a direction perpendicular to the direction in which the photoelectric conversion units are arranged. An image is read by scanning the photoelectric conversion device in a predetermined direction relative to a subject such as a document.

  In this photoelectric conversion device, the resolution at the time of image reading can be improved by reducing the size of the photoelectric conversion unit in the photoelectric conversion array. On the other hand, as the size of the photoelectric conversion unit is reduced, the amount of light incident on each photoelectric conversion unit is reduced and the sensitivity is lowered.

  The present invention has been made to solve the above-described problems, and suppresses a decrease in sensitivity in a photoelectric conversion apparatus that reads an image by scanning an object relatively in a predetermined direction. The purpose is to improve the resolution.

  In order to solve the above-described problem, the present invention provides a photoelectric conversion apparatus that reads the subject by scanning in a first direction relative to the subject, and includes a plurality of the photoelectric conversion devices along the first direction. A photoelectric conversion array that is arranged along a second direction perpendicular to the first direction, and a plurality of photoelectric conversion units that are arranged along the second direction and constitute the photoelectric conversion array And a microlens provided corresponding to each photoelectric conversion unit, and a light shielding unit having a light receiving window between each microlens and each photoelectric conversion unit, the first of the microlens The width in the first direction is larger than the width in the second direction, and the width of the light receiving window in the first direction is larger than the width in the second direction.

  According to the photoelectric conversion device of the present invention, it is possible to improve the resolution while suppressing a decrease in sensitivity when reading an image.

It is a figure for demonstrating the photoelectric conversion apparatus which concerns on 1st Embodiment. It is a figure for demonstrating the photoelectric conversion apparatus which concerns on 1st Embodiment. It is a figure for demonstrating the photoelectric conversion apparatus which concerns on 1st Embodiment. It is a figure for demonstrating the photoelectric conversion array which concerns on 1st Embodiment. It is a figure for demonstrating the photoelectric conversion apparatus which concerns on 1st Embodiment. It is a figure for demonstrating operation | movement of the photoelectric conversion apparatus which concerns on 1st Embodiment. It is a figure for demonstrating the photoelectric conversion apparatus which concerns on 2nd Embodiment. It is a figure for demonstrating the photoelectric conversion apparatus which concerns on 2nd Embodiment. It is a figure for demonstrating the photoelectric conversion apparatus which concerns on 2nd Embodiment. It is a figure for demonstrating the photoelectric conversion apparatus which concerns on 2nd Embodiment. It is a figure for demonstrating the photoelectric conversion apparatus which concerns on 2nd Embodiment. It is a figure for demonstrating the photoelectric conversion apparatus which concerns on 2nd Embodiment. It is a figure for demonstrating the photoelectric conversion apparatus which concerns on 2nd Embodiment. It is a figure for demonstrating the manufacturing method of a micro lens. It is a figure for demonstrating the manufacturing method of a micro lens. It is a figure for demonstrating the image reading apparatus using the photoelectric conversion apparatus which concerns on this invention.

  Hereinafter, an embodiment of a photoelectric conversion device according to the present invention will be described with reference to the drawings. In addition, the well-known or well-known technique of the said technical field is applied regarding the part which is not illustrated or described in particular in this specification. The embodiment described below is one embodiment of the present invention and is not limited thereto.

  An image reading apparatus using the photoelectric conversion device according to the present invention will be described with reference to FIG. FIG. 16 shows a configuration example of a color scanner as an image reading apparatus.

  The scanner includes a reading unit 401, a colorless and transparent mounting table 402, a light source 404, a lens 405, and a photoelectric conversion device 406. By irradiating the original 403 with white light from the light source 404 in a state where the original 403 is placed on the mounting table 402, the reflected light from the original 403 is imaged on the photoelectric conversion device 406 via the lens 405. At this time, the original 403 is read by the photoelectric conversion device 406 by moving the reading unit 401 in the first direction which is the direction of the arrow. The reflected light incident on the photoelectric conversion device 406 is color-separated by an optical filter, and for example, R, G, and B image signals are output.

  Next, the operation of the photoelectric conversion device including the photoelectric conversion array will be described with reference to FIG.

  First, the image of the document is read by relatively scanning the document using the photoelectric conversion device. The document is scanned in the direction in which the photoelectric conversion arrays are arranged. At this time, the R signal, G signal, and B signal acquired by each photoelectric conversion array are output from the photoelectric conversion device 1 to an analog-digital converter (hereinafter also referred to as ADC) 2. Each signal is converted from analog to digital by the ADC 2. Thereafter, a digital signal is output from the ADC 2 to the signal processor 3. The signal processor 3 performs predetermined processing such as shading correction on the digital signal, and outputs the R signal, the G signal, and the B signal to the output terminals Rout, Gout, and Bout. Through the above operation, information on the original read by the photoelectric conversion device can be obtained.

  Next, FIG. 8 illustrates an example of an equivalent circuit diagram of a photoelectric conversion unit of a photoelectric conversion device and a part for reading a signal from the photoelectric conversion unit.

  As illustrated in FIG. 8, the photoelectric conversion device includes a photodiode 502 (hereinafter also referred to as “PD”) that functions as a photoelectric conversion unit. In addition, a transfer unit 503, a floating diffusion unit (hereinafter also referred to as “FD”) 504, a reset unit 507, an amplification unit 505, and a selection unit 506 function as a read circuit. The reset unit 507, the amplification unit 505, and the selection unit 506 can each be formed of a transistor.

  The anode of the PD 502 is connected to the ground line, and the cathode is connected to the transfer unit 503. The transfer unit 503 is driven by a transfer pulse φTX input to its gate terminal, and transfers the charge generated in the PD 502 to the FD 504. The FD 504 functions as a charge-voltage conversion unit that converts the transferred charge into a voltage signal. The amplifying unit 505 is composed of, for example, a source follower, and the gate of a transistor (hereinafter also referred to as an amplifying transistor) constituting the source follower is electrically connected to the FD 504. The amplification transistor has a drain connected to the first power supply line VDD1 that supplies the first potential, and a source connected to the selection switch 506. The selection switch 506 is driven by a vertical selection pulse φSEL input to its gate, its drain is connected to the source of the amplification transistor, and its source is connected to the vertical signal line 508. When the vertical selection pulse φSEL becomes an active level (high level), the selection switch 506 of the pixel belonging to the corresponding row of the pixel array is turned on, and a signal corresponding to the source potential of the amplifier transistor is applied to the vertical signal line 508. Is output. The reset unit 507 supplies a predetermined voltage to the FD. A transistor constituting the reset unit 507 (hereinafter also referred to as a reset transistor) has a drain connected to a second power supply line VDD2 that supplies a second potential (reset potential), and a source connected to the FD 504.

  The photoelectric conversion device described in the following embodiment is suitably used for the above-described image reading device. That is, it is a photoelectric conversion device for reading a subject by scanning the subject in a relatively predetermined direction. Furthermore, a photoelectric conversion device described in the following embodiment can be configured with the configuration of FIG.

(First embodiment)
A photoelectric conversion apparatus 1 according to the first embodiment of the present invention will be described with reference to FIG.

  The photoelectric conversion device includes a plurality of photoelectric conversion arrays 110, 120, and 130. Each photoelectric conversion array includes a plurality of photoelectric conversion units and a reading area for reading signals from the photoelectric conversion units. The photoelectric conversion array 110 is an R photoelectric conversion array in which an optical filter that transmits light in the red wavelength region is disposed on the upper surface. The photoelectric conversion array 120 is a G photoelectric conversion array in which an optical filter that transmits light in the green wavelength region is disposed on the upper surface. The photoelectric conversion array 130 is a B photoelectric conversion array in which an optical filter that transmits light in a blue wavelength region is disposed on the upper surface. As shown in FIG. 1, the photoelectric conversion array 110, the photoelectric conversion array 120, and the photoelectric conversion array 130 are arranged at a predetermined interval. Each photoelectric conversion array is configured by repeatedly arranging a set of a photoelectric conversion unit and a reading region in which a circuit for reading a signal of the corresponding photoelectric conversion unit is arranged. In the figure, the portions delimited by the squares show how the above-mentioned sets are repeatedly arranged.

  Image scanning is performed by scanning (moving) the photoelectric conversion device 1 including the photoelectric conversion arrays 110 to 130 in a direction in which the photoelectric conversion arrays are arranged in parallel relative to the document. When reading an image, the photoelectric conversion device 1 may be moved, or the document may be moved. The number of photoelectric conversion arrays provided in the photoelectric conversion device and the wavelength region acquired by each photoelectric conversion device can be changed as appropriate. Hereinafter, in the description of the photoelectric conversion device according to the present invention, a direction in which a plurality of photoelectric conversion arrays are arranged (a direction in which scanning of a document is relatively performed) is referred to as a first direction, and the first direction. A direction perpendicular to each other (a direction in which each photoelectric conversion array extends) is defined as a second direction. A direction perpendicular to both the first direction and the second direction is defined as a third direction.

  Next, the detailed structure of the photoelectric conversion device according to the present invention will be described with reference to FIGS. Note that portions having the same functions as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. The same applies to other embodiments described later.

  2 and 3 show two photoelectric conversion arrays and a detailed structure of a part of the photoelectric conversion array.

  As shown in FIG. 2, the photoelectric conversion device includes a plurality of wirings 103 and photodiodes (hereinafter also referred to as PDs) 102 that function as photoelectric conversion units. Wirings 301, 302, and 303 are arranged in a direction orthogonal to the wiring 103. The wirings 301 and 303 are arranged in the first wiring layer located closest to the substrate side, and the wiring 302 is arranged in the second wiring layer arranged farther from the substrate than the first wiring layer. The wiring 103 is disposed on a third wiring layer that is disposed farther from the substrate than the second wiring layer. The wirings 301 to 303 and the wiring 103 function as a light shielding portion that blocks part of light incident on the substrate, and the light receiving window 104 is formed for each photoelectric conversion portion by the light shielding portion. In this example, the light shielding portion is formed by a plurality of wiring layers, but the light shielding portion may be formed by only one wiring layer. The third wiring layer, which is the uppermost layer among the exemplified wiring layers, is shielded from light so as to cover the boundary between the photoelectric conversion arrays, and the same photoelectric conversion array is used by the second wiring layer, which is the lower wiring layer. It is preferable to shield the light so as to cover the boundary portion of the PD 102 inside.

  Light that enters the photoelectric conversion device enters the PD 102 through the light receiving window 104. A region obtained by orthogonally projecting the wiring 103 onto the substrate is a reading region in which a reading circuit for reading signal charges generated in the PD 102 is arranged. In this embodiment, since the area of the PD 102 is larger than the orthogonal projection of the substrate of the light receiving window 104, the light receiving area of the PD 102 is defined by the light receiving window 104. The light shielding portion including the wirings 301 to 303 and the wiring 103 is provided between the PDs 102 when viewed from the third direction. The light shielding portion may be arranged so as to overlap each PD 102 within a range that does not excessively prevent the light from entering the PD 102. In this embodiment, the light shielding portion is formed by the wiring. However, a light shielding film may be provided between the PDs 102 in addition to the light shielding portion.

  Next, microlenses arranged corresponding to the PDs 102 will be described with reference to FIG. In FIG. 3, the wirings 301 to 303 described in FIG. 2 are omitted. That is, the planar positional relationship between the microlens, the pattern formed by the third wiring layer, and the PD is illustrated. For the PD 102, only the region of the PD 102 that can be seen through the light receiving window 104 when viewed from the third direction is illustrated. The photoelectric conversion device includes a microlens (hereinafter also referred to as ML) 101 on the PD 102 at a position corresponding to each PD 102. An optical filter (not shown) is provided between the ML 101 and the PD 102 so as to transmit light in a specific wavelength region. The light that has passed through the ML 101 passes through the optical filter and enters the PD 102 through the light receiving window 104 described above. The ML 101 has an elliptical shape when viewed from the third direction, and is preferably formed so that the major axis is parallel to the second direction and the minor axis is parallel to the first direction. In order to improve the light collection efficiency, the minor axis of ML 101 is formed to be larger than the width of light receiving window 104 in the second direction, and the major axis of ML 101 is larger than the width of light receiving window 104 in the first direction. Is also formed to be large.

  The end in the major axis direction of the ML 101 is configured to overlap with the wiring 103 when viewed from the third direction. The planar overlap of the ML 101 and the wiring 103 is configured such that light that is incident on the end of the ML 101 in the long axis direction and bent is incident on the PD 102 without being blocked by the wiring 103. According to such a configuration, it is possible to collect light from a wider range than the light incident between the wirings 103 in the first direction and make the light incident on the PD 102, thereby improving the sensitivity at the time of image reading. Can be made. In addition, it becomes possible to reduce the incidence of light on the region where the readout circuit for reading out the signal generated in the photoelectric conversion unit is arranged.

  In addition, the distance (width of the wiring 103 in the first direction) D1 between two adjacent light receiving windows 104 in the first direction is equal to the width of the light receiving window 104 in the first direction (two adjacent in the first direction). It is preferable that the distance between the wirings 103) is equal to or less than D2. It is preferable that the width D3 of the light receiving window 104 in the second direction is equal to D1, and the sum of D1 and D2 is an integer multiple of D3. According to such a configuration, it is possible to suppress color misregistration in the second direction when each photoelectric conversion array 110 to 130 reads a document signal.

  FIG. 4 shows a cross-sectional view of a part of the photoelectric conversion array shown in FIG.

  The PDs 102 are separated from each other by a separation region 304. The isolation region 304 can be formed using an insulator isolation formed by a LOCOS (Local Oxidation of Silicon) method or a STI (Shallow Trench Isolation) structure. An optical filter 311, a wiring 301 and a wiring 302 are provided between the ML 101 and the substrate. The optical filter has a predetermined transmission spectral characteristic and is configured to transmit only light of a specific wavelength.

  FIG. 5 shows a cross-sectional view of a part of the photoelectric conversion device shown in FIG.

  An optical filter 311, an optical filter 312, a wiring 202, a wiring 203, and a wiring 103 are provided between the ML 101 and the substrate. The wiring 202 is disposed on the first wiring layer located closest to the substrate, and the wiring 203 is disposed on the second wiring layer that is disposed farther from the substrate than the first wiring layer. The optical filters 311 and 312 have different transmission spectral characteristics, and are configured to transmit light of different wavelengths. A reading circuit 201 for reading a signal generated in the PD 102 is provided in a region below the wiring 103 and adjacent to the PD 102. Light incident on the reading circuit 201 is reduced by the wiring 103.

  In a photoelectric conversion apparatus that reads image information of a document by relatively scanning the document in a first direction, photoelectric conversion that contributes to image reading in a direction (second direction) orthogonal to the scanning direction of the document The width of the array is defined by the width of the document. Therefore, in order to improve the resolution when reading the document, it is necessary to increase the number of PDs 102 provided in a predetermined width in the second direction. However, as the number of pixels increases, the area of each PD 102 decreases, and the amount of light incident on the PD 102 decreases. However, in the present invention, the ML 101 provided on each PD 102 is formed such that the width in the first direction is larger than the width in the second direction. The light receiving window 104 provided between the PD 102 and the ML 101 and defining the light receiving surface of the PD 102 is formed so that the width in the first direction is larger than the width in the second direction. Accordingly, since light can be collected from a wider area in the first direction and incident on the PD 102, a decrease in sensitivity can be suppressed even when the resolution is improved.

  Furthermore, in the present invention, when viewed from the third direction, a wiring functioning as a light shielding portion is provided between the PDs 102. For this reason, it is possible to reduce the so-called color mixture in which the light passing through the ML 101 on the PD 102 or the gap between the MLs 101 enters the adjacent PD 102 and to increase the sensitivity. In order to efficiently collect light from the ML 101 to the PD 102, it is preferable that the distance between the ML 101 and the PD 102 is short. In the present invention, for the light receiving window formed by the shielding portion, the wiring 103 and the wiring 301 functioning as a light shielding portion or the wiring 301 or the light receiving window 104 so that the width in the first direction of the light receiving window 104 is larger than the width in the second direction. Wiring 303 is provided. As a result, even when the distance between the ML 101 and the PD 102 is reduced and the light collection efficiency is increased, light collected from a wide range in the first direction can be incident on the PD 102 without being blocked by the wiring. . In addition, since the width of the light shielding portion in the second direction is small, the resolution can be improved. In the first direction, a plurality of photoelectric conversion arrays each including a photoelectric conversion unit for detecting a different color are arranged, and the width of this direction does not substantially affect the resolution. The present invention pays attention to this point, and by making the width of the ML 101 and the light receiving window 104 in the first direction larger than the width in the second direction, the resolution can be reduced while suppressing the decrease in sensitivity. It made it possible to improve.

(Second Embodiment)
A photoelectric conversion apparatus according to the second embodiment of the present invention will be described with reference to FIG.

  The difference of this embodiment from the first embodiment is the shape of the ML 105 when viewed from the third direction. In the first embodiment, the ML 101 has an elliptical shape when viewed from the third direction. In contrast, when viewed from the third direction, the ML 105 according to the present embodiment has a linear region in which the outer edge of the ML 105 is parallel to the first direction. According to the configuration of such a microlens, more light can be collected, and thus the sensitivity can be further improved.

  A photoelectric conversion apparatus according to the third embodiment of the present invention will be described with reference to FIG. The difference between this embodiment and the first and second embodiments is the planar positional relationship between the microlens and the members constituting the readout circuit. The configuration of this embodiment can also be applied to the first and second embodiments.

  FIG. 9 is a diagram showing a layout when the PD and the reading circuit for reading the signal from the PD are viewed from the third direction. In the reference numerals in FIG. 9, in order to clarify the correspondence between each PD and the readout circuit, a common alphabet is added to the end of the reference numerals of the corresponding components. In the following description, the alphabet at the end is omitted. In this figure, a case where the amplification unit, the reset unit, and the selection unit are configured by MOS transistors will be described as an example. For example, it may be composed of a junction field effect transistor.

  A transfer gate electrode 601 that functions as a part of the transfer unit is disposed adjacent to the PD 102, and an FD 602 is disposed adjacent to the transfer gate electrode 601. The FD 602 is electrically connected to the gate electrode 606 of the amplification transistor by a wiring (not shown). A drain region 605 and a source region 607 are arranged with the gate electrode 606 interposed therebetween, and a first potential is supplied to the drain region of the amplification transistor through a wiring (not shown). The source region 607 of the amplification transistor is arranged in the same active region as the drain region of a transistor constituting the selection switch (hereinafter also referred to as selection transistor), and a vertical selection pulse is applied to the gate electrode 604 of the selection transistor by a wiring (not shown). Applied. The FD 602 is disposed adjacent to the gate electrode 603 of the reset transistor, and a drain region 609 to which a second potential is supplied by a wiring (not shown) is disposed at the other end of the gate electrode 603. That is, the source of the reset transistor and the FD are arranged in the same active region.

  As shown in FIG. 9, the photoelectric conversion device according to the present embodiment is configured such that at least a part of the active region constituting the FD 602 does not overlap with the ML 101. According to such a configuration, the parasitic capacitance generated between the FD 602 and the ML 101 can be reduced. Further, the gate electrode 606 of the amplification transistor and the gate electrode 604 of the selection transistor are configured to overlap with the adjacent ML 105 in the first direction. The gate electrode 603 of the reset transistor is configured not to overlap with the ML 105. Further, the active regions constituting the drain region 605 and the source region 607 of the amplification transistor and the source region 608 of the selection transistor are configured not to overlap with the ML 105 on the adjacent PD 102.

  FIG. 10 shows the layout shown in FIG. 9 with a part of the wiring added. In FIG. 10, the source / drain regions of the MOS transistors shown in FIG. 9 are omitted. Similarly to FIG. 9, in order to clarify the correspondence between each readout circuit and wiring, a common alphabet is added to the end of the reference numerals of the corresponding components. In the following description, the alphabet at the end is omitted.

  The wirings 610, 611, and 612 are all arranged in the second wiring layer. The wiring 610 applies a transfer pulse φTX to the transfer gate 601 of the transfer unit. The wiring 611 applies a reset pulse φRES to the gate electrode 603 of the reset transistor. The wiring 612 gives a vertical selection pulse φSEL to the gate electrode 604 of the selection transistor. The wiring 302 is provided so as to be positioned between the MLs 105 in the second direction when viewed from the third direction, and blocks light entering from the gaps between the MLs 105. In addition, the potential of the wiring 302 can be floating. Alternatively, a predetermined voltage may be applied from a different wiring layer.

  As shown in FIG. 10, when viewed from the third direction, the wirings 610 to 612 are arranged between the photoelectric conversion arrays, and are arranged with portions parallel to each other between the photoelectric conversion arrays. Further, the wirings 610, 611 and 612 are arranged so as not to overlap the ML 105.

  FIG. 11 is an enlarged view of an end portion of the photoelectric conversion array arranged in the first direction in the photoelectric conversion device.

  The wiring 615 is arranged in the second wiring layer, like the wirings 610 to 612. A wiring 615 is a wiring for connecting the above-described readout circuit and peripheral circuits including the horizontal selection circuit and the like. The wiring 615 is arranged along a second direction connecting a plurality of conductive patterns (four in the figure, hereinafter also referred to as a lead pattern) arranged along the first direction, and the first direction. It is formed by a pattern wider than the plurality of conductive patterns arranged along the direction. In the photoelectric conversion apparatus according to the present embodiment, not only a light receiving window for reading a document, a photoelectric conversion unit, and a region where the reading circuit is arranged, but also other regions (that is, photoelectric conversion for reading a document is not performed). (Region) is also provided with a dummy ML 620. It is preferable to arrange the above-described drawing patterns so as to overlap with the dummy ML 620. This is because a wiring for transmitting a signal to the peripheral circuit region is arranged between the dummy MLs 620 via the readout circuit unit from the photoelectric conversion unit. Although only a part of the outer periphery of the photoelectric conversion array is shown in FIG. 11, dummy MLs 620 are arranged on all outer periphery in the first direction and the second direction of the photoelectric conversion array.

  FIG. 12 shows the layout shown in FIG. 9 with the addition of the wiring of the third wiring layer located farther from the substrate than the first wiring layer and the second wiring layer. In FIG. 12, in order to clarify the positional relationship with each component shown in FIG. 9, the wiring of the third wiring layer is shown through. Similarly to FIG. 9, in order to clarify the correspondence between each readout circuit and the wiring, a common alphabet is added to the end of the reference numerals of the corresponding components. In the following description, the alphabet at the end is omitted.

  As shown in FIG. 12, when viewed from the third direction, the wiring 103 is arranged so as to overlap with the gate electrode 607 of the amplification transistor, the gate electrode 604 of the selection transistor, and the gate electrode 603 of the reset transistor. Moreover, it arrange | positions so that ML105 on PD102 adjacent in the 1st direction may overlap, and the light-receiving window of adjacent PD102 is formed.

  FIG. 13 is a diagram illustrating an optical black region (hereinafter also referred to as an OB region) arranged in a region other than the photoelectric conversion arrays 110 to 130. In the OB region, each component shown in FIG. 9 is arranged in the same layout as in FIG. 9 and has the same circuit configuration. The difference from the region of the photoelectric conversion array is that the wiring 630 arranged in the third wiring layer covers the PD 102 and no light enters the PD 102.

  With such a configuration, the signal (ie, the noise component) in a state where the light does not enter the PD 102 is read out, and the signal read out by reducing the noise component by subtracting the signal from the photoelectric conversion unit on which the reflected light from the original enters. Is possible. Further, by covering the PD with a wiring layer that is the farthest from the substrate among the wiring layers (hereinafter also referred to as the uppermost wiring layer), it is possible to provide an OB region with excellent light shielding performance.

(Microlens manufacturing method)
An ML manufacturing method according to the present invention will be described with reference to FIG. FIG. 14 is a process diagram when manufacturing ML by the reflow method.

  First, a transparent planarization layer 801 is formed on a substrate on which the PD 102 and the like are formed, and an optical filter 802 is formed thereon. Thereafter, a transparent flattening layer 803 and a thermally deformable resin layer 804 are formed on the optical filter 802 (FIG. 14A). Next, the thermally deformable resin layer 804 is patterned by a photolithography process to obtain a thermally deformable resin layer 804a (FIG. 14B). Thereafter, heat treatment is performed to cause the heat-deformable resin layer 804a to flow, and the lens shape is changed to obtain the microlens 101 (FIG. 14C).

  Another ML manufacturing method will be described with reference to FIG. FIG. 15 is a process diagram when manufacturing ML by the area gradation method.

  First, similarly to the reflow method, a transparent planarization layer 801, an optical filter 802, and a transparent planarization layer 803 are formed on a substrate on which the PD 102 and the like are formed, and a photosensitive resin layer 805 is formed on the transparent planarization layer 803. (FIG. 15A). Thereafter, ML1 is formed by a lithography process using a mask for area gradation microlens (FIG. 15B). Although the formation of the ML may be finished in this state, it is also effective to irradiate the substrate on which the microlens is formed in order to further improve the characteristics of the microlens.

1 Photoelectric conversion device 110, 120, 130 Photoelectric conversion array 101, 105 Microlens 102 Photodiode 103 Wiring 104 Light receiving window 301, 302, 303 Wiring

Claims (15)

A photoelectric conversion device that reads the subject by scanning in a first direction relative to the subject,
A plurality of photoelectric conversion arrays arranged along the first direction;
A plurality of photoelectric conversion units arranged along the second direction and constituting the photoelectric conversion array; and
A microlens provided on each of the photoelectric conversion units;
A light-shielding part having a light-receiving window between each microlens and each photoelectric conversion part,
The width of the micro lens in the first direction is larger than the width in the second direction, and the width of the light receiving window in the first direction is larger than the width in the second direction. A photoelectric conversion device. The photoelectric conversion device
Floating diffusion,
A transfer gate electrode for transferring the charge of the photoelectric conversion unit to the floating diffusion;
An amplification transistor having a gate electrically connected to the floating diffusion;
A selection transistor in which a source of the amplification transistor is connected to a drain and a selection pulse is input to a gate thereof;
A reset circuit for supplying a predetermined voltage to the floating diffusion by inputting a reset pulse to the gate; and a read circuit further comprising:
When viewed from a third direction orthogonal to the first direction and the second direction, the active region where the floating diffusion is disposed and the microlens overlap each other. The photoelectric conversion device according to claim 1. The photoelectric conversion device according to claim 2, wherein the transfer gate electrode and the microlens overlap each other when viewed from the third direction.   The gate electrode of the selection transistor overlaps with a microlens provided corresponding to a photoelectric conversion unit adjacent in the first direction when viewed from the third direction. 3. The photoelectric conversion device according to 3.   The gate electrode of the amplification transistor overlaps with a microlens provided corresponding to a photoelectric conversion unit adjacent in the first direction when viewed from the third direction. The photoelectric conversion device described.   6. The photoelectric conversion according to claim 1, wherein an interval between two light receiving windows adjacent in the first direction is equal to or smaller than a width of the light receiving window in the first direction. apparatus.   The photoelectric conversion device according to claim 6, wherein a width of the light receiving window in the first direction is equal to a distance between two light receiving windows adjacent in the first direction.   8. The photoelectric conversion device according to claim 1, wherein the microlens includes a linear region parallel to the first direction when viewed from the third direction. 9.   In the third direction, the first wiring layer is arranged at a position closest to the photoelectric conversion unit, and the wiring arranged in the first wiring layer has a first wiring layer in the second direction of the light receiving window. 9. The photoelectric conversion device according to claim 1, wherein a width is defined. A second wiring layer disposed in a position away from the first wiring layer in the third direction;
The second wiring layer has a conductive pattern disposed between the microlenses in the second direction when viewed from the third direction;
The conductive pattern is supplied with a predetermined voltage from a wiring arranged in a third wiring layer arranged at a position farther than the photoelectric conversion unit than the second wiring layer. Item 10. The photoelectric conversion device according to Item 9. A third wiring layer disposed at a position farther from the first wiring layer and the second wiring layer in the third direction, and a wiring disposed on the third wiring layer; The photoelectric conversion device according to claim 9, wherein a width of the light receiving window in a first direction is defined. In the second wiring layer,
A first wiring for supplying a transfer pulse to the transfer gate;
A second wiring for supplying a reset pulse to the gate of the reset transistor;
A third wiring for supplying a selection pulse to the gate of the selection transistor,
12. The photoelectric conversion device according to claim 10, wherein the first wiring, the second wiring, and the third wiring have regions that are parallel to each other. Furthermore, the photoelectric conversion device
It has a readout circuit provided corresponding to each photoelectric conversion unit,
The readout circuit includes
Floating diffusion,
A transfer gate electrode for transferring the charge of the photoelectric conversion unit to the floating diffusion;
An amplification transistor having a gate electrically connected to the floating diffusion;
A selection transistor in which a source of the amplification transistor is connected to a drain and a selection pulse is input to a gate thereof;
A reset transistor for supplying a predetermined voltage to the floating diffusion by inputting a reset pulse to the gate;
A first wiring layer disposed at a position closest to the photoelectric conversion unit in a third direction orthogonal to both the first direction and the second direction;
A second wiring layer disposed in a position farther from the first wiring layer in the third direction;
A third wiring layer disposed in a position away from the first wiring layer and the second wiring layer in the third direction;
A width in the second direction of the light receiving window is defined by the wiring arranged in the first wiring layer,
A width in the first direction of the light receiving window is defined by the wiring arranged in the third wiring layer,
Furthermore, the photoelectric conversion device has an optical black region,
The optical black region has the same circuit configuration as the photoelectric conversion unit and the readout circuit of the photoelectric conversion array,
The region corresponding to the photoelectric conversion portion of the photoelectric conversion array in the optical black region is covered with a third wiring layer when viewed from the third direction. The photoelectric conversion device described in 1. The photoelectric conversion device according to claim 13, further comprising: the microlens provided corresponding to a region corresponding to the photoelectric conversion unit of the photoelectric conversion array in the optical black region. A mounting table for mounting the subject;
A light source for irradiating the subject with light;
An image reading apparatus comprising: the photoelectric conversion device according to claim 1 that reads reflected light from the subject.

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