JP7643485B2 - Image pickup element and image pickup device - Google Patents

Description

The present invention relates to an imaging element and an imaging apparatus .

An imaging device in which a light-shielding layer made of a metal material is formed is known (Patent Document 1). There has long been a demand for improved focus detection accuracy.

JP 2016-51746 A

According to a first aspect of the invention, an imaging element includes a first microlens that transmits a first light traveling in a first direction and a second light traveling in a second direction, a second microlens that transmits a third light traveling in the first direction and a fourth light traveling in the second direction, a first photoelectric conversion unit that converts the first light that has passed through the first microlens into an electric charge, a second photoelectric conversion unit that converts the fourth light that has passed through the second microlens into an electric charge, a first electrode for outputting a signal based on the electric charge converted by the first photoelectric conversion unit, a second electrode for outputting a signal based on the electric charge converted by the second photoelectric conversion unit, a first light-shielding unit made of an organic material and provided between the first microlens and the first electrode , and a second light-shielding unit made of an organic material and provided between the second microlens and the second electrode, which is a light-shielding unit that blocks the third light that has passed through the second microlens .

1 is a diagram illustrating an example of a configuration of an imaging device according to a first embodiment. 2 is a diagram illustrating an example of pixel arrangement of an imaging element according to the first embodiment; 1 is a diagram illustrating an example of a configuration of a pixel of an image sensor according to a first embodiment; 10 is a diagram showing an example of the configuration of a pixel of an image sensor according to Modification 1; FIG. FIG. 11 is a diagram illustrating an example of the configuration of a pixel of an image sensor according to Modification 2. 11 is a diagram for explaining the characteristics of an AF pixel of an image sensor according to Modification 2. FIG. FIG. 11 is a diagram illustrating an example of the configuration of a pixel of an image sensor according to Modification 2. FIG. 11 is a diagram illustrating an example of the configuration of a pixel of an image sensor according to Modification 2.

First Embodiment
1 is a diagram showing an example of the configuration of a camera 1, which is an example of an imaging device according to a first embodiment. The camera 1 is made up of a camera body 2 and an interchangeable lens 3, which is an accessory that can be attached to the camera body 2. The interchangeable lens 3 is detachably attached to the camera body 2 by a mount unit (not shown). When the interchangeable lens 3 is attached to the camera body 2, a terminal provided on the body side connection unit 202 and a terminal provided on the lens side connection unit 302 are electrically connected. This enables power to be supplied from the camera body 2 to the interchangeable lens 3 and communication between the camera body 2 and the interchangeable lens 3.

Light from the subject is incident in the positive direction of the Z axis in Figure 1. As shown by the coordinate axes in Figure 1, the direction towards the viewer on the paper, perpendicular to the Z axis, is the positive X axis, and the direction downward on the paper, perpendicular to the Z and X axes, is the positive Y axis. In the following figures, the coordinate axes may be displayed so that the orientation of each figure can be seen, based on the coordinate axes in Figure 1.

The interchangeable lens 3 includes a photographing optical system (imaging optical system) 31, a lens control unit 32, and a lens memory 33. The photographing optical system 31 includes a plurality of lenses including a focus lens (focus adjustment lens) and an aperture, and forms a subject image on the imaging surface 22a of the imaging element 22 of the camera body 2. Note that the imaging surface 22a of the imaging element 22 is, for example, the surface on which a photoelectric conversion unit (described later) is arranged, or the surface on which a microlens is arranged.

The lens control unit 32 is composed of a processor such as a CPU, FPGA, or ASIC, and memories such as a ROM or RAM, and controls each part of the interchangeable lens 3 based on a control program. When a signal indicating the movement direction and amount of the focus lens is input from the body control unit 21, the lens control unit 32 moves the focus lens forward and backward in the direction of the optical axis L1 based on the signal to adjust the focal position of the photographing optical system 31. The lens control unit 32 also controls the aperture diameter of the iris based on the signal output from the body control unit 21.

The lens memory 33 is composed of a non-volatile storage medium, etc. Information related to the interchangeable lens 3 is stored in the lens memory 33. Data related to the infinity position and close position of the focus lens, data related to the shortest focal length and longest focal length of the interchangeable lens 3, data related to the F-number (aperture value), etc. are stored in the lens memory 33. Writing data to the lens memory 33 and reading data from the lens memory 33 are controlled by the lens control unit 32.

Next, the configuration of the camera body 2 will be described. The camera body 2 comprises a body control unit 21, an image sensor 22, a memory 23, a display unit 24, and an operation unit 25. The image sensor 22 is a CMOS image sensor or a CCD image sensor. The image sensor 22 captures a subject image formed by the photographing optical system 31. The image sensor 22 has multiple pixels, each having a photoelectric conversion unit, arranged two-dimensionally (in the row and column directions). The image sensor 22 photoelectrically converts the received light in the photoelectric conversion unit to generate a signal, and outputs the generated signal to the body control unit 21.

As described below, the image sensor 22 has imaging pixels that output signals used for image generation, and AF pixels (focus detection pixels) that output signals used for focus detection. The imaging pixels are arranged according to a Bayer array. The AF pixels are arranged to replace some of the imaging pixels, and are distributed over almost the entire imaging surface 22a of the image sensor 22.

The memory 23 is composed of a non-volatile storage medium, etc. Image data, control programs, etc. are recorded in the memory 23. Writing data to the memory 23 and reading data from the memory 23 are controlled by the body control unit 21. The display unit 24 displays an image based on the image data, an image showing a focus detection area (AF area) such as an AF frame, information related to shooting such as shutter speed and F-number, and a menu screen, etc. The operation unit 25 includes various setting switches such as a release button, a power switch, and switches for switching between various modes, and outputs signals based on the respective operations to the body control unit 21.

The body control unit 21 is composed of a processor such as a CPU, FPGA, or ASIC, and a memory such as a ROM or RAM, and controls each part of the camera 1 based on a control program. The body control unit 21 has an image data generation unit 21a and a focus detection unit 21b. The image data generation unit 21a performs various image processing on signals output from the imaging pixels of the image sensor 22 to generate image data. The image data generation unit 21a may also generate image data using signals output from the AF pixels of the image sensor 22. The image processing includes image processing such as tone conversion processing and color interpolation processing.

The focus detection unit 21b performs focus detection processing required for automatic focus adjustment (AF) of the photographing optical system 31. The focus detection unit 21b detects the in-focus position of the focus lens (the amount of movement of the focus lens to the in-focus position) for the image by the photographing optical system 31 to be focused (formed) on the imaging surface 22a of the image sensor 22. The focus detection unit 21b calculates the defocus amount by a phase difference detection method using first and second signals output from a pair of AF pixels (AF pixel pair) of the image sensor 22.

The focus detection unit 21b calculates the amount of image shift by performing a correlation calculation between a signal generated by capturing an image by a first light beam that has passed through a first pupil region of the exit pupil of the photographing optical system 31 and a signal generated by capturing an image by a second light beam that has passed through a second pupil region. The focus detection unit 21b converts this amount of image shift into a defocus amount based on a predetermined conversion formula. The focus detection unit 21b calculates the amount of movement of the focus lens to the in-focus position based on the calculated defocus amount.

The focus detection unit 21b judges whether the defocus amount is within a tolerance. If the defocus amount is within the tolerance, the focus detection unit 21b judges that the focus is achieved. On the other hand, if the defocus amount exceeds the tolerance, the focus detection unit 21b judges that the focus is not achieved, and transmits a signal indicating the amount of movement of the focus lens and an instruction to move the lens to the lens control unit 32 of the interchangeable lens 3. The lens control unit 32 moves the focus lens according to the amount of movement, thereby automatically adjusting the focus.
The configuration of the image sensor 22 according to this embodiment will be described below. In particular, the function of the absorbing portion 43 will be described with reference to FIGS.

The imaging element 22 will be briefly described below.
2, the image sensor 22 has a plurality of first pixels 11 and a plurality of second pixels 13. The first pixels 11 and the second pixels 13 are AF pixels. The first pixels 11 and the second pixels 13 form a pair and generate a signal indicating a focus adjustment state.
3, the first pixel 11 has a first microlens 44 on which the first light 61 and the second light 62 transmitted through the optical system are incident, a first photoelectric conversion unit 42 that performs photoelectric conversion of the light to generate electric charges, and a first absorbing unit 43 disposed between the first microlens 44 and the first photoelectric conversion unit 42. The first absorbing unit 43 absorbs a part of the second light 62 transmitted through the first microlens 44. The second pixel 13 has a second microlens 44 on which the first light 61 and the second light 62 transmitted through the optical system are incident, a second photoelectric conversion unit 42 that performs photoelectric conversion of the light to generate electric charges, and a second absorbing unit 43 between the second microlens 41 and the second photoelectric conversion unit 42. The second absorbing unit 43 absorbs a part of the first light 61 transmitted through the second microlens 41.

Figure 2 is a diagram showing an example of the arrangement of pixels in the image sensor 22 according to the first embodiment. In the image sensor 22, pixels are arranged two-dimensionally (in the row direction (±X direction) and the column direction (±Y direction)). The example shown in Figure 2 illustrates a total of 64 pixels in 8 rows and 8 columns. Note that the number and arrangement of pixels arranged in the image sensor 22 are not limited to the example shown.

The imaging element 22 has a plurality of imaging pixels 12 and AF pixels 11 and 13. The imaging pixels 12 are provided with one of three color filters 51 having different spectral characteristics of red (R), green (G), and blue (B). The imaging pixels 12 include a pixel (hereinafter referred to as an R pixel) having a color filter 51 having a spectral characteristic of dispersing light in a first wavelength range (red (R) light) of the incident light, a pixel (hereinafter referred to as a G pixel) having a color filter 51 having a spectral characteristic of dispersing light in a second wavelength range (green (G) light) of the incident light, and a pixel (hereinafter referred to as a B pixel) having a color filter 51 having a spectral characteristic of dispersing light in a third wavelength range (blue (B) light) of the incident light. The R pixel 12r, the G pixel 12g, and the B pixel 12b are arranged according to a Bayer array.

AF pixels 11 and 13 are arranged by replacing a part of the Bayer-arranged R, G, and B imaging pixels 12. AF pixels 11 and 13 are arranged with color filters 51 having a spectral characteristic of dispersing light in the second wavelength range (green (G) light) of the incident light. The color filters of AF pixels 11 and 13 may be color filters having a spectral characteristic of dispersing light in the first wavelength range (red (R) light) or light in the third wavelength range (blue (B) light). AF pixels 11 and 13 may also have filters having a spectral characteristic of dispersing light in the first, second, and third wavelength ranges of the incident light. Alternatively, color filters 51 may not be arranged on AF pixels 11 and 13.

The AF pixels 11 and 13 according to this embodiment are provided with an absorbing section 43 that absorbs incident light. The AF pixels 11 and 13 have different positions of the absorbing section 43. The absorbing sections 43 of the AF pixels 11 and 13 are arranged so that light that has passed through different regions of the exit pupil of the photographing optical system 31 is incident on the photoelectric conversion section 42. As will be described later, the absorbing sections 43 of the AF pixels 11 and 13 absorb a portion of the light 61 and 62 that has passed through different regions of the exit pupil of the photographing optical system 31. The photoelectric conversion section 42 of the AF pixels 11 and 13 photoelectrically converts the light that has passed through the microlens 44 and the color filter 51 and that has not been absorbed by the absorbing section 43.

As shown in FIG. 2, the image sensor 22 has a first pixel group 401 in which R pixels 12r and G pixels 12g are arranged alternately in the ±X directions, i.e., in the row direction, and a second pixel group 402 in which G pixels 12g and B pixels 12b are arranged alternately in the row direction. The image sensor 22 also has a third pixel group 403 in which G pixels 12g and AF pixels 11 and 13 are arranged in the row direction. In the example shown in FIG. 2, the AF pixels 11 and AF pixels 13 are arranged alternately with the G pixel 12g sandwiched between them.

The third pixel group 403 does not have to have both AF pixels 11 and 13. The second pixel group 402 may have the G pixel 12g and the AF pixel 11, and the third pixel group 403 may have the G pixel 12g and the AF pixel 13. The third pixel group 403 has the AF pixels 11 and 13 in multiple columns in which the B pixels 12b of the second pixel group 402 are arranged, but may have the AF pixels 11 and 13 in some of the multiple columns in which the B pixels 12b of the second pixel group 402 are arranged. Either one of the two pixels 11 in FIG. 3 or either one of the two pixels 13 may be omitted. The third pixel group 403 may have at least one of the AF pixels 11 and 13, the G pixel 12g, and the B pixel 12b.

Figure 3 is a diagram showing an example of the configuration of the imaging pixels and AF pixels of the imaging element 22 according to the first embodiment. Figure 3 shows one imaging pixel 12, one AF pixel 11, and one AF pixel 13 among the pixels provided in the imaging element 22. As described above, light that has passed through the imaging optical system 31 is incident on the imaging element 22 mainly in the positive direction of the Z axis. The light flux that has passed through the first pupil region, which is one of the approximately halved exit pupils of the imaging optical system 31, is shown by a solid arrow as the first light flux 61, and the light flux that has passed through the second pupil region, which is the other of the approximately halved exit pupils, is shown by a dashed arrow as the second light flux 62.

The imaging element 22 includes a substrate 110 and a wiring layer 111 that is laminated on the substrate 110. The substrate 110 is made of a semiconductor substrate such as silicon. The wiring layer 111 is a wiring layer that includes a conductor film (metal film) and an insulating film, and has multiple wirings, vias, and the like arranged therein. The conductor film is made of copper, aluminum, tungsten, or the like. The insulating film is made of an oxide film, a nitride film, or the like.

The AF pixel 11, the imaging pixel 12, and the AF pixel 13 each include a microlens 44, a first planarization layer 81, a color filter 51, a second planarization layer 82, a protective layer 83, a first electrode 45a, a photoelectric conversion unit 42, a second electrode 45b, and a storage unit 54 connected to the second electrode 45b via a wiring 53. The microlens 44 collects light incident from above through the imaging optical system 31 in FIG. 3. In the example shown in FIG. 3, the AF pixels 11 and 13 and the imaging pixel 12 each include a G color filter 51. FIG. 3 is a vertical cross-sectional view of the pixel group 403 in FIG. 2 cut along a cutting line extending in the ±X direction.

The first planarization layer (planarization film) 81 is made of an organic material such as resin and is provided between the microlens 44 and the color filter 51. The second planarization layer (planarization film) 82 is made of an organic material such as resin and is provided between the color filter 51 and the photoelectric conversion unit 42. A part of the second planarization layer 82 is provided between the color filter 51 and the absorbing unit 43, and another part of the second planarization layer 82 is provided between the absorbing unit 43 and the first electrode 45a. The protective layer (protective film) 83 is made of, for example, an organic material and is provided between the absorbing unit 43 and the photoelectric conversion unit 42. The protective layer 83 protects the first electrode 45a and the photoelectric conversion unit 42. In addition, in the direction in which light is incident, the absorbing unit 43 may be provided on the second planarization layer 82 or may be provided under the second planarization layer 82. The absorbing portion 43 may be provided on the protective layer 83 or may be provided under the protective layer 83. The absorbing portion 43 may also be provided within the protective layer 83. The absorbing portion 43 may be made of the same material as the second planarization layer 82 and the protective layer 83.

The photoelectric conversion unit 42 is composed of a photoelectric conversion film made of an organic material. The photoelectric conversion unit 42 converts incident light into an electric charge. The first electrode 45a is a transparent electrode and is made of ITO (indium tin oxide), titanium oxide, zinc oxide, or the like. The second electrode 45b is made of a metal material such as aluminum or tungsten.

As shown in FIG. 3, the first electrode 45a is an electrode common to the photoelectric conversion units 42 of multiple pixels, and is disposed on one side of the photoelectric conversion unit 42. The second electrode 45b is disposed on the other side of the photoelectric conversion unit 42 for each pixel. In this manner, the first electrode 45a and the second electrode 45b are disposed on either side of the photoelectric conversion unit 42. The first electrode 45a is an upper electrode of the photoelectric conversion unit 42, and the second electrode 45b is a lower electrode of the photoelectric conversion unit 42. The second electrode 45b is electrically connected to the storage unit 54 via a wiring 53 provided in the wiring layer 111.

The AF pixels 11 and 13 each have an absorbing portion 43 that absorbs a portion of the light beam transmitted (passed) through the microlens 44 and the color filter 51. The absorbing portion 43 is located between the color filter 51 and the photoelectric conversion portion 42, and is provided above the first electrode 45a of the photoelectric conversion portion 42. In this embodiment, the absorbing portion 43 is provided in the second planarization layer 82. In the example shown in FIG. 3, the absorbing portion 43 is provided in a partial region of the second planarization layer 82.

The absorbing section 43 is a filter (black filter) made of organic materials such as pigments, and has the property of absorbing light in the visible wavelength range. If the extinction coefficient of the absorbing section 43 for incident light with a wavelength of 530 nm is k, then k = approximately 0.15 to 0.20. The absorbing section 43 may be formed so that the extinction coefficient k = approximately 0.1 to 0.30.

The absorbing portion 43 of the AF pixel 11 is disposed in correspondence with an area of approximately the left half of the photoelectric conversion portion 42 (the -X direction side of the photoelectric conversion portion 42). At least a portion of the absorbing portion 43 of the AF pixel 11 is disposed in an area on the -X direction side of the center of the photoelectric conversion portion 42 of the AF pixel 11 in a plane (XY plane) intersecting with the direction in which light is incident (Z axis direction). The region 46 of the AF pixel 11 is an area corresponding to an area of approximately the right half of the photoelectric conversion portion 42 (the +X direction side of the photoelectric conversion portion 42). The region 46 of the AF pixel 11 is an area on the +X direction side of the center of the photoelectric conversion portion 42 of the AF pixel 11 in a plane (XY plane) intersecting with the direction in which light is incident (Z axis direction).

On the other hand, the absorbing portion 43 of the AF pixel 13 is disposed in correspondence with an area of approximately the right half of the photoelectric conversion portion 42 (the +X direction side of the photoelectric conversion portion 42). At least a portion of the absorbing portion 43 of the AF pixel 13 is disposed in an area on the +X direction side of the center of the photoelectric conversion portion 42 of the AF pixel 13 on a plane (XY plane) intersecting with the direction in which light is incident (Z axis direction). The region 46 of the AF pixel 13 is an area corresponding to an area of approximately the left half of the photoelectric conversion portion 42 (the -X direction side of the photoelectric conversion portion 42). The region 46 of the AF pixel 13 is an area on the -X direction side of the center of the photoelectric conversion portion 42 of the AF pixel 13 on a plane (XY plane) intersecting with the direction in which light is incident (Z axis direction).

In the AF pixel 11, a part of the second light beam 62 of the light beam transmitted through the microlens 44 and the color filter 51 is absorbed by the absorbing section 43. In the AF pixel 11, a first light beam 61 of the light beam transmitted through the microlens 44 and the color filter 51 passes through the region 46 and enters the photoelectric conversion section 42. The region 46 of the AF pixel 11 acts as an opening that allows the first light beam 61 that has passed through the microlens 44 and the color filter 51 to enter the photoelectric conversion section 42.

The photoelectric conversion unit 42 of the AF pixel 11 receives the first light beam 61 and photoelectrically converts the first light beam 61 to generate an electric charge. Note that a portion of the light that has passed through the absorbing unit 43 also enters the photoelectric conversion unit 42. The photoelectric conversion unit 42 of the AF pixel 11 photoelectrically converts a portion of the light that has passed through the absorbing unit 43 to generate an electric charge.

On the other hand, in the AF pixel 13, a part of the first light beam 61 of the light beam transmitted through the microlens 44 and the color filter 51 is blocked by the absorbing section 43. Also, in the AF pixel 13, a second light beam 62 of the light beam transmitted through the microlens 44 and the color filter 51 passes through the region 46 and enters the photoelectric conversion section 42. The region 46 of the AF pixel 13 acts as an opening that allows the second light beam 62 that has passed through the microlens 44 and the color filter 51 to enter the photoelectric conversion section 42.

The photoelectric conversion unit 42 of the AF pixel 13 receives the second light beam 62 and photoelectrically converts the second light beam 62 to generate an electric charge. Note that a portion of the light that has passed through the absorbing unit 43 also enters the photoelectric conversion unit 42. The photoelectric conversion unit 42 of the AF pixel 13 photoelectrically converts a portion of the light that has passed through the absorbing unit 43 to generate an electric charge.

In the imaging pixel 12, the first and second light beams 61 and 62 that pass through the first and second pupil regions of the exit pupil of the imaging optical system 31, respectively, are incident on the photoelectric conversion unit 42 via the microlens 44 and the color filter 51. The photoelectric conversion unit 42 of the imaging pixel 12 photoelectrically converts the first and second light beams 61 and 62 to generate electric charges.

The charge photoelectrically converted by the photoelectric conversion unit 42 of each pixel is transferred to the storage unit 54 via the wiring 53 by the first electrode 45a and second electrode 45b of that pixel. The storage unit 54 accumulates (holds) the charge transferred to the storage unit 54. Each pixel has an amplification transistor (not shown) and outputs a signal based on the charge accumulated in the storage unit 54. The first electrode 45a and second electrode 45b form part of an output unit that outputs a signal based on the charge generated by the photoelectric conversion unit 42.

The AF pixel 11 outputs a first signal Sig1 based on the electric charge accumulated by photoelectrically converting the first light beam 61 that has passed through the first pupil region. The AF pixel 13 outputs a second signal Sig2 based on the electric charge accumulated by photoelectrically converting the second light beam 62 that has passed through the second pupil region. The imaging pixel 12 outputs a signal based on the electric charge accumulated by photoelectrically converting the first light beam 61 and the second light beam 62.

The signals output from each pixel are input to a signal processing unit (not shown) arranged on the substrate 110, where they are subjected to signal processing, and then output to the body control unit 21 of the camera 1. This signal processing unit includes an analog/digital conversion unit (AD conversion unit) that converts the signals output from the pixels into digital signals.

2 and 3, the AF pixels 11 and 13 are arranged in the row direction (±X direction), but may be arranged in the column direction (±Y direction). When the AF pixels 11 and 13 are arranged in the column direction, the absorbing portion 43 of the AF pixel 11 is arranged corresponding to one of the regions of approximately the upper half or lower half of the photoelectric conversion portion 42, and the absorbing portion 43 of the AF pixel 13 is arranged corresponding to the other region of approximately the upper half or lower half of the photoelectric conversion portion 42. For example, at least a part of the absorbing portion 43 of the AF pixel 11 is arranged in a region on the +Y direction side of the center of the photoelectric conversion portion 42 of the AF pixel 11. At least a part of the absorbing portion 43 of the AF pixel 13 is arranged in a region on the -Y direction side of the center of the photoelectric conversion portion 42 of the AF pixel 13.

As described above, the AF pixel 11 and the AF pixel 13 have the absorbing portion 43 at different positions in the direction intersecting the direction in which light is incident. The absorbing portion 43 of the AF pixel 11 absorbs a part of the second light flux 62, and the absorbing portion 43 of the AF pixel 13 absorbs a part of the first light flux 61. As a result, the photoelectric conversion portion 42 of the AF pixel 11 mainly receives the first light flux 61, and the photoelectric conversion portion 42 of the AF pixel 13 mainly receives the second light flux 62. The first signal Sig1 output from the AF pixel 11 has a large signal component due to light passing through the first pupil region, and the second signal Sig2 output from the AF pixel 13 has a large signal component due to light passing through the second pupil region. Therefore, by using the first signal Sig1 output from the AF pixel 11 and the second signal Sig2 output from the AF pixel 13, information on the phase difference of the subject image can be obtained and the defocus amount can be calculated.

In addition, in this embodiment, the absorbing portion 43 is made of a material that absorbs visible light with almost no reflection. This makes it possible to reduce stray light due to reflection and to avoid affecting signals generated in each pixel. Furthermore, a part of the second planarization layer (planarization film) 82 is disposed between the absorbing portion 43 and the first electrode 45a. This makes it possible to improve the planarization of the absorbing portion 43 and to suppress variations in the characteristics of the absorbing portion 43 of each pixel. Note that the absorbing portion 43 may be disposed on the first electrode 45a of the photoelectric conversion portion 42 without providing the second planarization layer 82.

When attempting to form a light-shielding film (metal light-shielding film) made of a metal material for phase difference detection on an image sensor on which a photoelectric conversion film made of an organic material is arranged, etching is required to form the metal light-shielding film in a predetermined pattern, which may damage other layers (films) such as the photoelectric conversion film and transparent electrodes. In this case, it is considered that the characteristics of the photoelectric conversion film and transparent electrodes will deteriorate, dark current will increase, and the quality of the pixel signal will decrease, resulting in a decrease in focus detection accuracy. In addition, if a metal light-shielding film is arranged directly above the photoelectric conversion film, load capacitance (parasitic capacitance) will be generated between the metal light-shielding film and the photoelectric conversion film, and between the metal light-shielding film and the signal line for controlling the pixel, making it impossible to drive the pixel at high speed, and there is a risk that the image sensor 22 will not be able to operate at high speed.

In addition, it is generally difficult to form a metal film in an organic film, and it is also difficult to arrange a metal light-shielding film in a planarizing film made of an organic material. For this reason, when a metal light-shielding film is arranged, there is a risk that a step will occur between pixels, causing variations in the characteristics of each pixel. In the first place, it may be impossible to form a metal light-shielding film on top of a photoelectric conversion film made of an organic material.

On the other hand, in this embodiment, the imaging element 22 is provided with a light-shielding film made of an organic material. When forming a light-shielding film made of an organic material, there is no need to use an etching solution for a metal light-shielding film, and the light-shielding film made of an organic material is formed in a pattern using a developer for a photoresist (e.g., a negative resist). This makes it possible to suppress damage to other layers and prevent deterioration of pixel characteristics. In addition, it is possible to prevent the load capacitance as described above from occurring, and to avoid a decrease in processing speed.

Next, an example of the operation of the camera 1 according to this embodiment will be described. When the power switch of the operation unit 25 of the camera 1 is operated, the first signal Sig1 of the AF pixel 11, the second signal Sig2 of the AF pixel 13, and the signal of the imaging pixel 12 are sequentially output from the imaging element 22. The focus detection unit 21b of the body control unit 21 calculates the defocus amount by a phase difference detection method using the first signal Sig1 and the second signal Sig output from the AF pixels 11 and 13 of the imaging element 22. The lens control unit 32 adjusts the focus by moving the focus lens of the imaging optical system 31 to a focus position based on the defocus amount calculated by the focus detection unit 21b. Note that instead of moving the focus lens, the imaging element 22 may be moved in the direction of the optical axis L1 of the imaging optical system 31.

The image data generating unit 21a of the body control unit 21 generates image data based on signals output from the imaging pixels 12 of the image sensor 22. The image data generating unit 21a generates image data for a through image (live view image) of the subject and image data for recording. The display unit 24 displays an image based on the image data for the through image. The image data for recording is recorded in the memory 23.

According to the above-described embodiment, the following advantageous effects can be obtained.
(1) The image sensor 22 includes a first pixel 11 having a first microlens 44 on which a first light 61 and a second light 61 that have passed through the optical system are incident, a first photoelectric conversion unit 42 that performs photoelectric conversion of the light to generate an electric charge, and a first absorption unit 43 that is provided between the first microlens 44 and the first photoelectric conversion unit 42 and absorbs a portion of the second light 62 that has passed through the first microlens 44; and a second pixel 13 having a second microlens 44 on which the first light 61 and the second light 62 are incident, the second photoelectric conversion unit 42 that performs photoelectric conversion of the light to generate an electric charge, and the second absorption unit 43 that is provided between the second microlens 44 and the second photoelectric conversion unit 42 and absorbs a portion of the first light 61 that has passed through the second microlens 44. In this embodiment, the image sensor 22 is provided with an AF pixel 11 having an absorbing portion 43 that absorbs a portion of the second light flux 62, and an AF pixel 13 having an absorbing portion 43 that absorbs a portion of the first light flux 61. For this reason, information on the phase difference of the subject image can be obtained by using signals output from the AF pixel 11 and the AF pixel 13. It is possible to calculate the amount of image shift and the amount of defocus by using the signals output from the AF pixel 11 and the AF pixel 13.

(2) The imaging device 1 includes an image sensor 22 and a detector (focus detector 21b) that detects the focus of the optical system based on the first signal Sig1 and the second signal Sig2. In this embodiment, the image sensor 22 outputs to the body control unit 21 a first signal Sig1 based on the charge obtained by photoelectrically converting the first light beam 61, and a second signal Sig2 based on the charge obtained by photoelectrically converting the second light beam 62. Therefore, the focus detector 21b of the body control unit 21 can calculate the defocus amount using the first signal Sig1 and the second signal Sig2. The camera 1 can perform focus adjustment based on the defocus amount calculated by the focus detector 21b.

The following modifications are also within the scope of the present invention, and one or more of the modifications may be combined with the above-described embodiment.

(Variation 1)
4 is a diagram showing an example of the configuration of pixels of an image sensor according to the first modification. The image sensor 22 according to this modification has an absorbing portion 47 provided between adjacent pixels. In the example shown in FIG. 4, the absorbing portion 47 is provided in the second planarization layer 82 at the boundary between adjacent pixels. In the camera 1, abnormal light (ghost light) may occur due to light passing through the photographing optical system 31 being reflected by the inside of the housing of the camera body 2 or the microlens 44 of the image sensor 22, and light with a large angle of incidence may be incident on the microlens 44 of each pixel.

In this modified example, a portion of the ghost light that passes through the microlens 44 and the color filter 51 enters the absorbing portion 47 and is absorbed by the absorbing portion 47. This reduces the light that leaks from a pixel to the photoelectric conversion portion 42 of the adjacent pixel. This prevents the signal generated by the pixel from being mixed with a signal component due to light leaking from an adjacent pixel. This prevents a decrease in the accuracy of the defocus amount calculated using the signals output from the AF pixels 11 and 13, and a decrease in the image quality of the image generated using the signal output from the imaging pixel 12. Note that the above description applies to the effects of various types of incident light with large angles of incidence.

(Variation 2)
The absorbing portion may be formed so that the upper and lower portions have different widths. FIG. 5 is a diagram showing an example of the configuration of a pixel of an image sensor according to Modification 2. As shown in FIG. 5, the width of the absorbing portion 43 may be made smaller in the upward direction (-Z direction side). If the width of the upper portion of the absorbing portion 43 is Wt1 and the width of the lower portion of the absorbing portion 43 is Wb1, the absorbing portion 43 is formed so that Wb1>Wt1. In this case, an inclined surface 48 is formed at the edge portion of the absorbing portion 43. The area of the upper portion of the absorbing portion 43 is smaller than the area of the lower portion of the absorbing portion 43.

The transmittance of the absorbing portion 43 changes depending on the shape of the absorbing portion 43, and the amount of light received by the photoelectric conversion portion 42 changes. Therefore, the relationship between the angle of incidence of light incident on the AF pixel and the signal level of the signal output from the AF pixel changes between when the absorbing portion 43 does not have an inclined surface 48 (FIG. 3) and when the absorbing portion 43 has an inclined surface 48 (FIG. 5).

Figure 6 is a diagram showing the relationship between the angle of incidence and the output signal of the AF pixel. In Figure 6, the vertical axis indicates the signal level of the signal output from the AF pixel, and the horizontal axis indicates the angle of incidence of light incident on the AF pixel. Waveform 61a indicates the signal level of the output signal of AF pixel 11 when there is no inclined surface 48, and waveform 61b indicates the signal level of the output signal of AF pixel 11 when there is inclined surface 48. Waveform 62a indicates the signal level of the output signal of AF pixel 13 when there is no inclined surface 48, and waveform 62b indicates the signal level of the output signal of AF pixel 13 when there is inclined surface 48. These waveforms represent the performance of pupil division by the AF pixel, and are parameters that affect AF performance.

Comparing the waveforms (61a, 62a) when there is no inclined surface 48 with the waveforms (61b, 62b) when there is an inclined surface 48, the inclination of the waveform is gentler when there is an inclined surface 48. When there is an inclined surface 48, as the angle of incidence becomes smaller (approaching 0), the incident light is gradually absorbed by the absorbing portion 43, and the inclination of the waveforms (61b, 62b) becomes gentler. In this way, by providing an inclined surface 48 at the end of the absorbing portion 43, it is possible to change the pupil division characteristics of the AF pixel.

The cross-sectional shape of the end of the absorbing portion 43 may not change linearly, but may be curved as shown in Figs. 7(a) and (b). Also, as shown in Fig. 8, the width of the absorbing portion 43 may be increased upward (towards the -Z direction). If the width of the upper part of the absorbing portion 43 is Wt2 and the width of the lower part of the absorbing portion 43 is Wb2, the absorbing portion 43 is formed so that Wb2 < Wt2. The area of the upper part of the absorbing portion 43 is larger than the area of the lower part of the absorbing portion 43. In this way, the pupil division characteristics of the AF pixel can be adjusted by adjusting the shape of the absorbing portion 43. Also, multiple types of AF pixel pairs (AF pixel 11, AF pixel 13) whose inclinations of the inclined surface 48 are different from each other may be arranged. In this case, the camera 1 may select an AF pixel pair to be used for focus detection from among the multiple types of AF pixel pairs.

(Variation 3)
Generally, light passing through the exit pupil of the photographing optical system 31 is incident almost perpendicularly on the central part of the imaging surface 22a of the image sensor 22, whereas light is incident obliquely on the peripheral part located outside the central part, i.e., on the region away from the center of the imaging surface 22a. For this reason, the area and position of the absorbing part 43 of each pixel may be configured to be different depending on the position of the pixel in the image sensor 22 (e.g., image height). In addition, the position of the exit pupil and the exit pupil distance of the photographing optical system 31 are different between the central part and the peripheral part of the imaging surface 22a of the image sensor 22. For this reason, the area and position of the absorbing part 43 of each pixel may be configured to be different depending on the position of the exit pupil and the exit pupil distance. This makes it possible to increase the amount of light incident on the photoelectric conversion part via the photographing optical system 31, and to appropriately perform pupil division even when light is incident obliquely.

(Variation 4)
In the above-described embodiment, an example in which a photoelectric conversion film is used as the photoelectric conversion unit has been described. However, the photoelectric conversion unit 42 may be configured with a photoelectric conversion film made of an inorganic material. A photodiode may be used as the photoelectric conversion unit.

(Variation 5)
In the above embodiment, a primary color (RGB) color filter is used in the imaging element 22, but a complementary color (CMY) color filter may be used.

(Variation 6)
The imaging elements and imaging devices described in the above-mentioned embodiments and variant examples may be applied to cameras, cameras built into smartphones, tablets, PCs, in-vehicle cameras, cameras mounted on unmanned aerial vehicles (drones, radio-controlled aircraft, etc.), and the like.
The above-mentioned absorbing portion may be used as a filter (band pass filter) that blocks visible light and transmits infrared light. In this case, the photoelectric conversion portion efficiently receives the infrared light, enabling focus detection using the infrared light. Therefore, the present invention can be applied to a camera that uses images using infrared light (for example, an in-vehicle camera or a medical camera).

Although various embodiments and modifications have been described above, the present invention is not limited to these. Other embodiments that are conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention.

1...imaging device, 2...camera body, 3...interchangeable lens, 21...body control unit, 21a...image data generation unit, 21b...focus detection unit, 22...imaging element, 31...imaging optical system, 42...photoelectric conversion unit, 44...microlens, 43...absorption unit, 45a...first electrode, 45b...second electrode, 51...color filter, 81...first planarization layer, 82...second planarization layer, 110...substrate

Claims (16)

a first microlens that transmits a first light beam traveling in a first direction and a second light beam traveling in a second direction;
a second microlens that transmits a third light beam traveling in the first direction and a fourth light beam traveling in the second direction;
a first photoelectric conversion unit that converts the first light transmitted through the first microlens into an electric charge;
a second photoelectric conversion unit that converts the fourth light transmitted through the second microlens into an electric charge;
a first electrode for outputting a signal based on the charge converted by the first photoelectric conversion unit;
a second electrode for outputting a signal based on the charge converted by the second photoelectric conversion unit;
a first light-shielding portion that blocks the second light transmitted through the first microlens, the first light-shielding portion being made of an organic material and provided between the first microlens and the first electrode ;
a second light-shielding portion that blocks the third light transmitted through the second microlens, the second light-shielding portion being made of an organic material and provided between the second microlens and the second electrode;
An imaging element comprising: 2. The imaging device according to claim 1 ,
the first microlens transmits the first light having passed through a first region of an optical system and the second light having passed through a second region different from the first region;
The second microlens transmits the third light transmitted through the first region and the fourth light transmitted through the second region of the imaging element. 3. The imaging device according to claim 1 ,
the first photoelectric conversion unit converts the first light transmitted through the first microlens and the light transmitted through the first microlens and the first light-shielding unit into electric charges;
The second photoelectric conversion unit is an imaging element that converts the fourth light transmitted through the second microlens and the light transmitted through the second microlens and the second light blocking unit into electric charges. 4. The imaging device according to claim 1 ,
a length of the first light-shielding portion is shorter on the first microlens side than on the first photoelectric conversion portion side in a direction intersecting a direction in which light transmitted through the first microlens is incident;
An imaging element, wherein in a direction intersecting a direction in which light transmitted through the second microlens is incident, the length of the second light-shielding portion is shorter on the second microlens side than on the second photoelectric conversion portion side. 4. The imaging device according to claim 1 ,
an area of the first light-shielding portion is smaller on the first microlens side than on the first photoelectric conversion portion side in a direction intersecting a direction in which light transmitted through the first microlens is incident;
An imaging element, wherein an area of the second light-shielding portion is smaller on the second microlens side than on the second photoelectric conversion portion side in a direction intersecting a direction in which light transmitted through the second microlens is incident. 4. The imaging device according to claim 1 ,
a length of the first light-shielding portion is longer on the first microlens side than on the first photoelectric conversion portion side in a direction intersecting a direction in which light transmitted through the first microlens is incident;
An imaging element, wherein in a direction intersecting a direction in which light transmitted through the second microlens is incident, the length of the second light-shielding portion is longer on the second microlens side than on the second photoelectric conversion portion side. 4. The imaging device according to claim 1 ,
an area of the first light-shielding portion is larger on the first microlens side than on the first photoelectric conversion portion side in a direction intersecting a direction in which light transmitted through the first microlens is incident;
An imaging element, wherein in a direction intersecting a direction in which light transmitted through the second microlens is incident, an area of the second light-shielding portion is larger on the second microlens side than on the second photoelectric conversion portion side. The imaging device according to claim 1 ,
a planarization layer or a protection layer provided between the first light-shielding portion and the first photoelectric conversion portion ;
the first photoelectric conversion unit converts the first light transmitted through a first filter having a first spectral characteristic into an electric charge;
the second photoelectric conversion unit converts the fourth light transmitted through a second filter having the first spectral characteristic into an electric charge;
The second photoelectric conversion unit is disposed adjacent to the first photoelectric conversion unit in the row direction of the image sensor. 9. The imaging device according to claim 1 ,
An imaging element comprising: a planarization layer or a protection layer provided between the second light-shielding portion and the second photoelectric conversion portion. The imaging device according to any one of claims 1 to 9 ,
the first light-shielding portion absorbs the second light,
The second light-shielding portion is an imaging element that absorbs the third light. The imaging device according to any one of claims 1 to 10 ,
the first light blocking portion is a black filter,
The second light blocking portion is a black filter. The imaging device according to any one of claims 1 to 11 ,
the first photoelectric conversion unit is a photoelectric conversion unit made of an organic material,
The second photoelectric conversion unit is an image pickup element that is a photoelectric conversion unit made of an organic material. The imaging device according to any one of claims 1 to 12 ,
a third electrode for outputting a signal based on the charge converted by the first photoelectric conversion unit;
a fourth electrode for outputting a signal based on the charge converted by the second photoelectric conversion unit,
the first photoelectric conversion unit is provided between the first electrode and the third electrode,
The second photoelectric conversion unit is provided between the second electrode and the fourth electrode of the imaging element. The imaging device according to any one of claims 1 to 13 ,
a first output unit that outputs a first signal that is a signal based on the charges converted by the first photoelectric conversion unit and is used for focus detection;
a second output section that outputs a second signal that is based on the charges converted by the second photoelectric conversion section and is used for focus detection. The imaging device according to claim 14 ;
a detection unit that performs focus detection of an optical system based on the first signal and the second signal. An imaging device comprising the imaging element according to claim 1 .

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