WO2015122300A1 - Élément de formation d'image, dispositif de fabrication et dispositif électronique - Google Patents

Élément de formation d'image, dispositif de fabrication et dispositif électronique Download PDF

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Publication number
WO2015122300A1
WO2015122300A1 PCT/JP2015/052797 JP2015052797W WO2015122300A1 WO 2015122300 A1 WO2015122300 A1 WO 2015122300A1 JP 2015052797 W JP2015052797 W JP 2015052797W WO 2015122300 A1 WO2015122300 A1 WO 2015122300A1
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Prior art keywords
microlens
light
pixel
light shielding
unit pixel
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PCT/JP2015/052797
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English (en)
Japanese (ja)
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大塚　洋一
納土　晋一郎
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ソニー株式会社
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14625—Optical elements or arrangements associated with the device
    • H01L27/14627—Microlenses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B19/00—Condensers, e.g. light collectors or similar non-imaging optics
    • G02B19/0004—Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed
    • G02B19/0009—Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed having refractive surfaces only
    • G02B19/0014—Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed having refractive surfaces only at least one surface having optical power
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B19/00—Condensers, e.g. light collectors or similar non-imaging optics
    • G02B19/0033—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use
    • G02B19/0076—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use for use with a detector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/1462—Coatings
    • H01L27/14621—Colour filter arrangements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/1462—Coatings
    • H01L27/14623—Optical shielding

Definitions

  • This technology relates to an image sensor, a manufacturing apparatus, and an electronic device.
  • the present invention relates to an imaging device, a manufacturing apparatus, and an electronic device that can suppress flare and ghost and improve image quality.
  • Japanese Patent Application Laid-Open No. H10-260260 proposes to improve image quality by reducing optical color mixing and flare by forming a light shielding film formed through an insulating layer at the pixel boundary of the light receiving surface.
  • Patent Document 1 in order to improve the image quality of a back-illuminated imaging device having a unit pixel size of 1.75 ⁇ m, a light-shielding film is formed at the unit pixel boundary, so that optical color mixing caused by diffracted reflected light from the surface of the microlens Reducing flare is disclosed.
  • the present technology has been made in view of such a situation, and is intended to improve image quality.
  • An imaging device includes a plurality of unit pixels formed in a light receiving region, a light shielding film formed at a boundary portion between the unit pixels, and a microlens formed for each unit pixel.
  • the unit pixel is a substantially square lattice of 1.98 ⁇ m or more
  • the microlens is a square having a side of less than 1.98 ⁇ m and squares of 2 or more natural numbers for each unit pixel. Yes.
  • the light shielding film may be further formed at a boundary portion between the microlenses.
  • An inner lens is further provided between the micro lens and the photodiode, and the inner lens is a main of at least one of the plurality of condensing spots collected by the plurality of micro lenses.
  • the light beam may be formed so as to be condensed toward the unit pixel center direction.
  • Detecting the phase difference makes it possible to be a pixel for detecting the focal point.
  • a light-shielding film formed from the boundary portion of the microlens to the substantially central portion can be further provided.
  • the unit pixel may include a light receiving unit that acquires light information from different directions.
  • a light shielding wall provided in a direction perpendicular to the light shielding film can be further provided.
  • a manufacturing apparatus includes a plurality of unit pixels formed in a light receiving region, a light shielding film formed at a boundary portion between the unit pixels, and a microlens formed for each unit pixel.
  • the unit pixel is a substantially square lattice of 1.98 ⁇ m or more
  • the microlens is a square having a side of less than 1.98 ⁇ m and squares of 2 or more natural numbers for each unit pixel. Manufacturing an image sensor.
  • the microlens can be formed by a hot melt flow method.
  • the microlens can be formed by a dry etching method.
  • An electronic apparatus includes a plurality of unit pixels formed in a light receiving region, a light shielding film formed at a boundary portion between the unit pixels, and a microlens formed for each unit pixel.
  • the unit pixel is a substantially square lattice of 1.98 ⁇ m or more
  • the microlens is a square having a side of less than 1.98 ⁇ m and squares of 2 or more natural numbers for each unit pixel.
  • a signal processing unit that performs signal processing on a signal output from the image sensor.
  • An imaging device includes a plurality of unit pixels formed in a light receiving region, a light shielding film formed at a boundary portion between the unit pixels, and a microlens formed for each unit pixel.
  • the unit pixel is a substantially square lattice of 1.98 ⁇ m or more
  • the microlens is a square having a side of less than 1.98 ⁇ m for each unit pixel, and squares of 2 or more natural numbers are formed.
  • the imaging element is manufactured.
  • a signal from the image sensor is processed.
  • the present technology described below can be applied to an image sensor that can suppress optical color mixing and flare and can improve image quality.
  • a front-illuminated image sensor and a back-illuminated image sensor will be described, optical color mixing and flare will be described, and then an image sensor to which the present technology is applied will be described.
  • CMOS Complementary MOS
  • FIG. 1 is a configuration diagram of a surface irradiation type imaging device 110.
  • a semiconductor substrate 112 is configured to include a pixel region 113 in which a plurality of unit pixels 116 each including a photodiode (PD) 111 serving as a photoelectric conversion unit and a plurality of pixel transistors are formed.
  • PD photodiode
  • each photodiode 111 is isolated by an element isolation region 115 by an impurity diffusion layer.
  • a multilayer wiring layer 119 in which a plurality of wirings 118 are arranged via an interlayer insulating film 117 is formed on the surface side of the semiconductor substrate 112 where the pixel transistors are formed.
  • the wiring 118 is formed except for a portion corresponding to the position of the photodiode 111.
  • An on-chip color filter 121 and an on-chip microlens 122 are sequentially formed on the multilayer wiring layer 119 via a planarizing film 120.
  • the on-chip color filter 121 is configured by arranging, for example, red (R), green (G), and blue (B) color filters.
  • the substrate surface on which the multilayer wiring layer 119 is formed is the light receiving surface 123, and light L is incident from the substrate surface side.
  • each of the microlens 122 and the color filter 121 is formed in a single unit corresponding to the unit pixel 116.
  • FIG. 2 is a configuration diagram of the backside illumination type image sensor 130. The same parts as those of the front-illuminated image sensor 110 shown in FIG.
  • the semiconductor substrate 112 includes a pixel region 113 in which a plurality of unit pixels 116 each including a photodiode 111 serving as a photoelectric conversion unit and a plurality of pixel transistors are formed.
  • the pixel transistor is formed on the surface side of the substrate, and in FIG. 2, the gate electrode 114 is shown to schematically indicate the presence of the pixel transistor.
  • Each photodiode 111 is isolated by an element isolation region 115 by an impurity diffusion layer.
  • a multilayer wiring layer 119 in which a plurality of wirings 118 are formed through an interlayer insulating film 117 is formed on the surface side of the semiconductor substrate 112 where the pixel transistors are formed.
  • the wiring 118 can be formed regardless of the position of the photodiode 111.
  • an insulating layer 128, an on-chip color filter 121, and an on-chip microlens 122 are sequentially formed on the back surface of the semiconductor substrate 112 facing the photodiode 111.
  • the substrate L opposite to the substrate surface on which the multilayer wiring layer and the pixel transistor are formed is the light receiving surface 132, and the light L is incident from the substrate backside.
  • the opening of the photodiode 111 can be widened, and high sensitivity can be achieved.
  • the microlens 122 and the color filter 121 are each formed in a single unit corresponding to the unit pixel 116.
  • the back-illuminated image sensor 130 is generally used for a relatively small camera called a compact digital camera or a mobile camera. For this reason, the back-illuminated image sensor 130 is often composed of unit pixels 116 of less than about 2.0 ⁇ m, and so-called fine pixel sensitivity and shading characteristics are improved.
  • the back-illuminated image sensor 130 can also be applied to an image sensor for a digital still camera (DSC) such as an APS size or a 35 mm size.
  • DSC digital still camera
  • the pixel size of these image sensors is a fine pixel as described above. Generally, it is approximately 2.0 ⁇ m or more as compared with the image pickup device provided.
  • the back-illuminated image sensor 130 has a multilayer wiring layer on the front surface side, so that the opening area of the photodiode 111 can be formed wide, so that more incident light can be taken in, and imaging is performed. The sensitivity and shading characteristics of the element are improved.
  • the size of the microlens 122 formed corresponding to the unit pixel 116 of the image sensor is normally formed approximately equal to the size of the unit pixel 116.
  • light is incident on the unit pixel group A of the back-illuminated image sensor 130 (incident light), and the formation pitch of the microlenses 122 formed on the surface of the back-illuminated image sensor 130 (P lens).
  • incident light the unit pixel group A of the back-illuminated image sensor 130
  • P lens formation pitch of the microlenses 122 formed on the surface of the back-illuminated image sensor 130
  • FIG. 3 shows an example in which the pitch of unit pixels 116 (P pixels) and the formation pitch of micro lenses 122 (P lenses) are formed equal.
  • the diffraction order (m) and diffraction angle ( ⁇ ) of the diffracted reflected light can be expressed by the following formula (1).
  • (P lens) ⁇ sin ⁇ m ⁇ ⁇ (1)
  • Equation (1) ⁇ is the wavelength of incident light. From equation (1), it can be seen that when ⁇ is constant, the diffraction order m decreases as the P lens, which is the formation pitch of the microlenses 122, decreases, and as the P lens increases, the diffraction order m increases.
  • the diffraction angle ⁇ at the same diffraction order m increases as the microlens formation pitch P lens decreases. Furthermore, it can be read that the diffraction order m increases as the wavelength ⁇ is relatively small.
  • light is shielded through the insulating layer 128 at the boundary of the unit pixel 116 in the light receiving region where the unit pixels 116 including the photoelectric conversion unit (photodiode 111) are arranged.
  • a film 141 is formed.
  • the size of the unit pixel 116 exceeds 1.75 ⁇ m
  • the formation size of the microlens 122 is increased in accordance with the size, as described with reference to the above formula (1).
  • the diffraction order (m) of the diffracted reflected light and the diffraction angle ( ⁇ ) at the same diffraction order (m) are reduced.
  • optical color mixing and flare in the image sensor due to re-reflection from a seal glass or an infrared cut filter (IRCF) formed on the front surface of the light incident side of the image sensor described later. Gets worse. Therefore, when the size of the unit pixel 116 is increased, it is necessary to provide a mechanism that does not deteriorate optical color mixing and flare.
  • IRCF infrared cut filter
  • the light beam of the diffracted and reflected light shown in FIG. 3 is shown as a single straight line, but actually it is reflected in a state having a width such as ⁇ 1 to ⁇ 2 as shown in FIG.
  • the diffraction reflection angle of the diffraction order (m) is a diffraction reflection light having a width of ( ⁇ 2 ⁇ 1) in the figure.
  • FIG. 5A shows a plan view of the back-illuminated image sensor 130 (a view when the back-illuminated image sensor 130 is viewed from above), and FIG. 5B shows a light receiving region composed of a plurality of unit pixels 116.
  • FIG. 5B is a cross-sectional view taken along line ab shown in FIG. 5A.
  • the incident light shown in FIG. 5B enters the image sensor through the IRCF 151 and the seal glass 152 formed above the image sensor.
  • the light incident on the imaging device generates diffracted reflected light having a certain diffraction order (m) and a diffraction reflection angle ( ⁇ ) according to the formation pitch (P lens) of the surface of the micro lens 122 (( ⁇ (minus ) Diffracted reflected light is not shown))).
  • the diffracted reflected light is reflected by the seal glass 152 formed above the image sensor and becomes reflected light having a visible light component. Further, the light component that has passed through the seal glass 152 is reflected by the IRCF 151 formed further above, and becomes reflected light having a large red component in the visible light region (indicated by a broken line in FIG. 6).
  • the light reflected by the seal glass 152 and the IRCF 151 travels again toward the image sensor, and a part of the component is photoelectrically converted by the photodiode 111 of the image sensor. This becomes optical color mixing or flare, which may deteriorate the image quality of the image sensor.
  • the diffracted and reflected light by the microlens 122 shown in FIG. 5 has a width and proceeds to the seal glass 152 and the IRCF 151. Therefore, since the light reflected by the seal glass 152 and re-entering the image sensor is also incident with a width, it becomes a substantially streak-like optical color mixture or flare as shown in FIG. ).
  • the light reflected by the IRCF 151 becomes reflected light having a large red component due to the light transmittance characteristics of the IRCF 151 (the reflected light obtained by extracting the reflected light component of the red component light from the reflected light component having a width). Therefore, it becomes a substantially spot-like optical color mixture or flare (shown in the shape of a spot in the figure).
  • FIG. 6 shows a table in which the orders at which the diffracted reflected light is generated when the size of the unit pixel 116 is made larger than 1.75 ⁇ m.
  • the numerical value of the order of the diffracted and reflected light shown in FIG. 6 is calculated at 400 nm on the short wavelength side in the visible light region where the diffraction order is likely to occur, as can be seen from Equation (1).
  • the unit pixel side direction in the table shown in FIG. 6 is the length in the side direction of the square lattice pixel shown in FIG. 7 (unit pixel size), and the unit pixel diagonal direction is the diagonal direction of the square lattice pixel. Length (unit pixel size ⁇ ⁇ 2).
  • the order of the generated diffracted reflected light is “ ⁇ 4”, and when it is 2.000 ⁇ m, it is “ ⁇ 5”.
  • the generation order is increased by “2”.
  • the length becomes ⁇ 2 times longer than the length of the unit pixel in the side direction, so that from ⁇ 1750 to 1.979 ⁇ m from equation (1), “ ⁇ 6” is obtained. 1. It becomes “ ⁇ 7” at 980 ⁇ m, and the generation order increases by “2”.
  • the diffraction angle of the diffracted reflected light of the same order shown in FIG. ⁇ ) is also reduced.
  • the size of the unit pixel 116 formed in the light receiving region is configured to be at least 1.980 ⁇ m or more, and the pixel boundary portion of the unit pixel 116 has at least the pixel in plan view.
  • a light shielding film is formed so as to surround the periphery.
  • a plurality of microlenses 122 are formed corresponding to the unit pixel 116.
  • the length of one side of the microlens 122 is less than 1.980 ⁇ m, and a plurality of unit pixels 116 are formed so as to divide the unit pixels 116 into substantially equal areas with n squares of approximately squares. Note that n is a natural number of 2 or more.
  • FIG. 8 is a unit pixel 116 formed in the light receiving region of the image sensor, and a broken line in the figure indicates a boundary line between adjacent pixels.
  • FIG. 8B shows a state in which one side of the unit pixel 116 is divided into two in the vertical and horizontal directions, and four microlenses are formed in the unit pixel 116.
  • the length of one side of the unit pixel 116 is 1.980 ⁇ m
  • the length of one side of the microlens 122 is 1 ⁇ 2 of 1.980 ⁇ m.
  • FIG. 8C shows a state in which nine microlenses are formed in the unit pixel 116 by dividing one side of the unit pixel 116 into three in the vertical and horizontal directions.
  • the length of one side of the unit pixel 116 is 1.980 ⁇ m
  • the length of one side of the microlens 122 is one third of 1.980 ⁇ m.
  • FIG. 8D shows a state in which one side of the unit pixel 116 is divided into four in the vertical and horizontal directions to form 16 microlenses in the unit pixel 116.
  • FIG. When the length of one side of the unit pixel 116 is 1.980 ⁇ m, the length of one side of the microlens 122 is a quarter of 1.980 ⁇ m.
  • FIG. 8B to FIG. 8D show examples in which one side of the unit pixel 116 is divided into 2 to 4 and the number of microlenses is 4, 9, and 16, respectively.
  • the present technology is limited to these. It is not a statement to show that. That is, the plurality of microlenses formed corresponding to the unit pixel 116 have a side length of less than 1.980 ⁇ m, and n (n is a natural number equal to or greater than 2) square square unit pixels. Any image sensor may be used as long as it is formed in a plurality so as to divide 116 into substantially equal areas.
  • the microlens 122 is manufactured by a thermal melt flow method will be described with reference to FIG.
  • the manufacturing method described with reference to FIG. 9 can be applied to the manufacture of the back-illuminated image sensor 130 in which the size of the unit pixel 116 formed in the light receiving region is 1.98 ⁇ m or more.
  • a light shielding film 141 is formed between adjacent pixels through an insulating film 128 formed on the semiconductor substrate 112 that constitutes the back-illuminated image sensor 130.
  • a planarizing film 201 made of, for example, acrylic resin is formed.
  • a color filter 121 made of, for example, primary colors such as red, blue, and green is formed to output a color image of the image sensor.
  • color filter 121 complementary colors such as yellow, cyan, and magenta may be used. Further, the color filter 121 may not be used depending on the use of the image sensor.
  • the color filter 121 is made of, for example, a photosensitive negative resist and is formed by a photolithography method.
  • a planarizing film 202 made of, for example, an acrylic resin is formed.
  • a microlens material 203 made of, for example, a novolak-based, styrene-based, acrylic-based, or copolymerized positive photosensitive resin thereof is formed into a substantially rectangular shape by photolithography. .
  • the microlens material 203 includes, for example, a diazonaphthoquinone-based photosensitive material
  • the sensitivity characteristic of the image pickup element is deteriorated because it has light absorption on the visible light short wavelength side.
  • the microlens material 203 that has been developed by the photolithography method is irradiated with ultraviolet rays such as i-rays and bleaching exposure is performed so that light absorption is reduced. Also good.
  • a plurality of microlens materials 203 are formed in substantially the same shape corresponding to the unit pixel 116.
  • 9E shows a state in which two are formed in the cross-sectional direction.
  • the number of microlenses corresponding to the number of microlenses 122 to be formed such as three or four, is described.
  • a lens material 203 is formed.
  • the heat treatment is performed at a temperature equal to or higher than the heat softening point of the microlens material 203 that has been subjected to the development treatment, and the microlens 122 having a microlens shape is obtained by performing the heat melt flow treatment. It is formed.
  • a plurality of microlenses 122 are formed in substantially the same shape corresponding to the unit pixel 116.
  • FIG. 9F shows a state in which two are formed in the cross-sectional direction.
  • a plurality of microlenses 122 are formed on the unit pixel 116.
  • the second manufacturing method of the image sensor will be described with reference to FIG.
  • the case where the microlens 122 is manufactured by, for example, a dry etching method will be described as an example.
  • the size of the unit pixel 116 formed in the light receiving region can be applied when manufacturing the back-illuminated image sensor 130 having a size of 1.98 ⁇ m or more.
  • a styrenic resin or the like is formed on the image sensor in which the color filter 121 is formed through the processes described with reference to FIGS. 9A to 9C.
  • a microlens material 221 is formed.
  • a positive photosensitive resin 222 made of, for example, a novolak type is formed into a substantially rectangular shape by a development process in a photolithography method.
  • a plurality of positive photosensitive resins 222 are formed in substantially the same shape corresponding to the unit pixel 116.
  • FIG. 10 illustrates the case where two are formed in the cross-sectional direction.
  • a microlens shape is obtained by performing a heat treatment at or above the heat softening point of the positive photosensitive resin 222 that has been subjected to the development treatment, and performing a heat melt flow treatment.
  • the positive type photosensitive resin 222 having a microlens shape is subjected to a dry etching process using a fluorocarbon-based gas or the like on the microlens material 221 formed on the base.
  • the microlens 122 is transferred by an etching method so that the effective area of the microlens 122 is enlarged.
  • FIG. 10D shows a state in which two are formed in the cross-sectional direction.
  • a plurality of microlenses are formed on the unit pixel 116.
  • FIG. 11A shows a light shielding film 141 formed with one opening corresponding to the unit pixel 116. This corresponds to the cross section of FIG.
  • the broken line represents the boundary of the unit pixel 116, and the thick line around it represents the light shielding film 141.
  • a light shielding film 141 is provided in each peripheral portion of one unit pixel 116.
  • the opening of the light shielding film 141 has substantially the same size and shape as the opening of the unit pixel 116.
  • FIG. 11B shows red, blue and green color filters 121 formed corresponding to the unit pixel 116. This corresponds to C in FIG. 9, and when the state of the image sensor shown in C in FIG. 9 is viewed from above, a filter of a color assigned to each unit pixel 116 is provided for each unit pixel 116. ing.
  • the diagonal line of B of FIG. 11 is a different diagonal line for every color, and has shown that the color filter 121 of red, blue, and green is arrange
  • FIG. 11C shows a plurality of microlenses 122 formed in substantially the same shape corresponding to the unit pixel 116.
  • FIG. 11C shows an example in which four microlenses 122 are formed corresponding to one unit pixel 116.
  • C in FIG. 11 corresponds to F in FIG. 9 and D in FIG. 10, and when the state of the image sensor shown in F in FIG. 9 and D in FIG.
  • the micro lens 122 is provided.
  • FIG. 11D shows a cross section of the image sensor when the light shielding film 141 is provided around the 1 unit pixel 116 as shown in FIG. 11A. Moreover, the arrow shown with the broken line in D of FIG. 11 represents the stray light component used as an optical color mixture or a flare component.
  • the stray light component may enter the photodiode 111.
  • FIG. 12 is a diagram for explaining a case where a light shielding film 141 is provided not only in the periphery of one unit pixel 116 but also in the unit pixel 116 in accordance with the shape of the microlens 122.
  • FIG. 12A is a diagram showing the shape of the light-shielding film 141 formed on the image sensor, as in FIG. 11A.
  • the light shielding film 141 shown in FIG. 12A is provided with a light shielding film 141 in the periphery of one unit pixel 116, and a light shielding film 141 is also provided in the unit pixel 116 in a cross shape.
  • the light shielding film 141 is provided on the outer peripheral portion of one microlens 122.
  • the opening of the light shielding film 141 is about 1 ⁇ 4 the size of the opening of the unit pixel 116, It becomes a shape.
  • the opening portions of the four light shielding films 141 correspond to one unit pixel 116.
  • FIG. 12B is the same as the color filter 121 shown in FIG. 11B
  • FIG. 12C is the same as the microlens 122 shown in FIG. 11C.
  • D in FIG. 12 represents a cross section of the image sensor when the light shielding film 141 is provided around and inside the 1-unit pixel 116 as shown in FIG. 12A.
  • the arrow shown with the broken line in D of FIG. 12 represents the stray light component used as an optical color mixture or a flare component.
  • a plurality of microlenses 122 formed in pairs corresponding to the openings of the light shielding films 141 of the light shielding films 141 formed with the plurality of openings corresponding to the unit pixels 116 are formed.
  • the opening area of the light shielding film 141 is reduced, and the sensitivity characteristics of the image sensor are slightly deteriorated.
  • the light shielding function by the light shielding film 141 works and is advantageous.
  • FIG. 13 is a cross-sectional view of the image sensor for explaining another shape of the microlens.
  • FIG. 13A is a plan view of the image sensor as viewed from above. A broken line indicates the boundary of the unit pixel 116, and a hatched portion in the broken line indicates a microlens.
  • FIG. 13A shows an example in which four microlenses are formed in one unit pixel 116.
  • FIG. 13B and FIG. 13C are cross-sectional views taken along the line ab shown in FIG. 13A, respectively.
  • the image sensor shown in FIG. 13B is different from the image sensor shown in FIG. 13C only in the portion where the light shielding film 141 is provided, and the other portions are the same.
  • the light shielding film 141 of the image sensor shown in B of FIG. 13 is provided on the outer peripheral portion of the one-unit pixel 116, similarly to the light shielding film 141 shown in FIG.
  • the light shielding film 141 of the image sensor shown in FIG. 13C is provided in the outer peripheral portion and inside of the one unit pixel 116, similarly to the light shielding film 141 shown in FIG.
  • the microlens 311 shown in FIG. 13B is formed in a substantially rectangular shape and a substantially rectangular shape in plan view.
  • a microlens 311 shown in FIG. 13B includes a microlens region 312 formed of a material having a refractive index n and a non-microlens region 313 having a refractive index n ′, and uses the difference in refractive index (n > N ′), and the light is condensed by using the phase difference of the light incident on the image sensor.
  • FIG. 13C shows a plurality of microlenses 311 formed in pairs corresponding to the openings of the light shielding films 141 of the light shielding films 141 formed having a plurality of openings corresponding to the unit pixels 116. Show. FIG. 13C shows an example in which four light shielding film openings are formed for one unit pixel 116, and microlenses 311 are formed corresponding to the four light shielding film openings, respectively. ing.
  • the present technology can be applied.
  • the light shielding film 141 may be formed in a portion corresponding to the outer peripheral portion of the unit pixel 116, which is a portion of the non-micro lens region 313. As shown in C, the non-microlens region 313 may be formed.
  • FIG. 14B and FIG. 15 show cross-sectional views of the image pickup device including the inner lens, and for comparison, FIG. 14A shows a cross-sectional view of the image pickup device not including the inner lens. In the figure, broken arrows indicate the traveling direction of light.
  • FIG. 14A, FIG. 14B, and FIG. 15 are back-illuminated image sensors 130 in which a plurality of microlenses 122 are provided in one unit pixel 116.
  • a plurality of microlenses 122 are provided in one unit pixel 116.
  • an example in which four microlenses 122 are provided in the unit pixel 116 is shown.
  • FIG. 14A is configured such that an inner lens is not formed
  • the back-illuminated image sensor 130 illustrated in FIG. 14B is configured such that an inner lens 411 is formed. It is said that.
  • the margin between the focused end portion and the edge of the light shielding film 141 is small.
  • a circle is shown in the margin portion of the focused end portion and the edge portion of the light shielding film 141 that are collected. The distance between the focusing end and the edge of the light shielding film 141 in this circle is short.
  • the margin between the focused end portion that has been condensed and the edge of the light shielding film 141 is large.
  • a circle is shown in the margin portion of the focused end portion and the edge portion of the light shielding film 141 that are collected. The distance between the focusing end and the edge of the light shielding film 141 in this circle is wide.
  • the light from the microlens 122 can be collected more efficiently by providing the inner lens 411.
  • the inner lens 411 may not be formed, the inner lens 411 is provided particularly when, for example, an improvement in sensitivity deterioration (luminance shading) at the outer periphery of the light receiving area where the oblique incident light component increases. It is good to have a configuration.
  • the inner lens 411 is made of, for example, plasma silicon nitride (P-SiN; refractive index: about 1.9 to 2.0), and the planarizing film 201 is made of, for example, acrylic resin (having a refractive index of about 1.5). be able to.
  • P-SiN plasma silicon nitride
  • the planarizing film 201 is made of, for example, acrylic resin (having a refractive index of about 1.5). be able to.
  • the shape of the inner lens 411 may be a hemispherical shape as in the case of the microlens 122 shown in FIG. 14B, but may be other shapes.
  • a rectangular inner lens 421 as shown in FIG. 15 may be provided in the planarization film 422.
  • the inner lens 421 shown in FIG. 15 has a substantially rectangular shape in a cross-sectional view and a substantially rectangular shape as shown in FIG. 13A in a plan view, like the microlens 311 shown in B or 13C of FIG. Is formed. Such a rectangular inner lens 421 may be used.
  • the inner lens 421 is, for example, plasma silicon nitride (P-SiN; refractive index is about 1.9 to 2.0), and the planarizing film 201 is, for example, acrylic resin (having a refractive index of about 1.5). Etc.).
  • the inner lens 411 and the inner lens 421 direct the principal ray of at least one of the plurality of condensing spots collected by the plurality of micro lenses 122 toward the center of the unit pixel 116. What is necessary is just to be formed so that it may condense.
  • FIGS. 16A and 16B schematic views of the front side illumination type image sensor 110 and the back side illumination type image sensor 130 are shown in FIGS. 16A and 16B, respectively.
  • a transistor electrode (a gate electrode 114 in FIG. 16A) is formed above a photodiode 111, and a multilayer wiring layer 119 (in the drawing, the first layer from the photodiode 111 side) is formed above the transistor electrode.
  • Second layer, and third layer are also formed.
  • the distance d1 from the surface of the photodiode 111 to the microlens 122 becomes longer. Since the distance d1 is long, the microlens 122 is formed so that the thickness t1 is reduced and the curvature is increased.
  • the transistor and the multilayer wiring layer 119 are formed on the side opposite to the surface on which the microlens 122 is formed. In FIG. 16B, not shown.
  • a light shielding film 141 is formed as a single layer corresponding to the unit pixel 116 above the photodiode 111 on the surface side where the microlens 122 is formed. Therefore, the distance d2 from the surface of the photodiode 111 to the microlens 122 is shortened.
  • the microlens 122 is formed so that the thickness t2 is increased and the curvature is decreased.
  • the microlens material 203 of adjacent pixels comes into contact with each other when the microlens material 203 formed by thickening the microlens material 203 is obtained by thermal reflow after the development processing by the photolithography method, the microlens 122 is fused. The shape will collapse.
  • the microlens 122 is formed by dry etching
  • the microlens material 221 is formed thick
  • the positive photosensitive resin 222 is formed thick
  • the microlens 122 is formed by heat reflow. After obtaining the lens shape (in this case, it is also difficult to control during thermal reflow), it is necessary to carry out dry etching for a long time.
  • FIG. 17 is a diagram showing a state in which the present technology is applied to the back-illuminated image sensor 130 shown in FIG. 16B and a plurality of microlenses 122 are formed in one unit pixel 116.
  • the back-illuminated image sensor 130 of FIG. 16B even when a part of the light condensed by the microlens 122 is kicked by the light shielding film 141, it is shown in FIG. According to the back-illuminated imaging element 130, for example, even if the film thickness t2 of the microlens 122 is the same, the dimension of the bottom of the microlens 122 is half (1/2) in the illustrated microlens 122. Since the curvature of the microlens is reduced accordingly, the light can be collected efficiently.
  • the size of the bottom of the microlens 122 is half (1/2) in the illustrated microlens 122, the size of the microlens 122 itself is small even when the size of the unit pixel 116 is large. It is not necessary to form the microlens 122 thick with high accuracy.
  • the autofocus method for digital cameras mainly includes a contrast method and a phase difference method.
  • the contrast method is a method in which the lens is moved so that the point with the highest contrast is in focus.
  • auto-focusing can be performed by reading a part of the image of the image sensor, and no other auto-focus optical system is required.
  • the phase difference method is a method to which so-called triangulation technology is applied, and is a method for obtaining a distance by an angle difference when the same subject is viewed from two different points.
  • images of light passing through different parts of the lens for example, light beams on the right and left sides of the lens are used.
  • the phase difference method by measuring the distance, it is required how much the lens needs to be moved to the in-focus position.
  • phase difference auto-focusing performs auto-focusing using the phase difference method using some of the imaging pixels.
  • the imaging element is provided with a condensing microlens, for example, a microlens 122 (FIG. 17), and a diaphragm member for limiting light incident on the microlens, for example, a light shielding film 141.
  • a condensing microlens for example, a microlens 122 (FIG. 17)
  • a diaphragm member for limiting light incident on the microlens for example, a light shielding film 141.
  • the phase difference method does not require time for moving the lens back and forth in order to find the focal position, so that high-speed autofocus can be realized.
  • the description will be continued by taking as an example the case where the present technology is applied to an image sensor that performs phase difference autofocus.
  • the back side illumination type imaging device will be described as an example, but the present technology described below can be applied to a front side illumination type imaging device.
  • FIG. 18 is a diagram for explaining phase difference autofocus.
  • a predetermined number of pixels in a pixel array unit (not shown) in which pixels are two-dimensionally arranged in a matrix are assigned to phase difference detection pixels.
  • a plurality of phase difference detection pixels are provided at predetermined positions in the pixel array section.
  • phase difference detection pixel shown in FIG. 18 is, for example, a part of the back-illuminated image sensor 130 shown in FIG. 17 and a portion including the phase difference detection pixel.
  • FIG. 2 is a diagram illustrating a part necessary for the imaging, in which an imaging element provided with one microlens per photodiode is illustrated.
  • the phase difference detection pixel is a pixel used when detecting a focal point by the phase difference method
  • the imaging pixel is a pixel different from the phase difference detection pixel and is a pixel used for imaging.
  • the image sensor shown in FIG. 18 includes microlenses 511-1 to 510-4, light shielding films 512-1 to 512-3, and photodiodes 513-1 to 513-4.
  • the image sensor is configured such that light enters through the lens group 501.
  • the photodiode 513-2 and the photodiode 513-3 function as phase difference detection pixels, and pixels for acquiring an image signal for autofocus (focus detection). It is said that.
  • the photodiode 513-1 and the photodiode 513-4 arranged at a position sandwiching the photodiode 513-2 and the photodiode 513-3 are used as imaging pixels, and acquire an image signal by light from a subject. It is a pixel for this purpose.
  • the photodiode 513-1 receives light from the subject condensed by the microlens 511-1, and the photodiode 513-2 receives light from the subject condensed by the microlens 511-2,
  • the photodiode 513-3 receives light from the subject collected by the microlens 511-3, and the photodiode 513-4 receives light from the subject condensed by the microlens 511-4. It is configured.
  • the light shielding film 512-1 is provided so that the light from the microlens 511-1 does not enter the photodiode 513-2 and the light from the microlens 511-2 does not enter the photodiode 513-1. It has been.
  • the light shielding film 512-3 prevents light from the microlens 511-4 from entering the photodiode 513-3, and prevents light from the microlens 511-3 from entering the photodiode 513-4. It is provided as follows.
  • the light shielding film 512-1 and the light shielding film 512-3 are thus provided mainly to prevent light leaking to adjacent pixels (photodiodes), and thus are provided between the adjacent photodiodes 214. ing.
  • the light shielding film 512-2 has a function of selecting a light incident angle and receiving light in addition to a function of preventing light leaking to an adjacent pixel (photodiode) (hereinafter referred to as a light receiving film). It also has a function for realizing (described as separation ability).
  • the light shielding film 512-2 is provided from approximately the center of the photodiode 513-2 to approximately the center of the photodiode 513-3 so that the light enters the photodiode 513-2.
  • the presence of the light shielding film 512-2 makes it possible to separate and receive the light coming from the left part of the lens group 501 and the light coming from the right part.
  • the focus position is detected as shown in FIG. Can do.
  • the output from the photodiode 513-2 and the output from the photodiode 513-3 do not match at the rear pin or the front pin (the outputs of the paired phase difference detection pixels do not match).
  • the output from the photodiode 513-2 and the output from the photodiode 214-3 match (the outputs of the paired phase difference detection pixels match).
  • the focus detection is realized by moving the lens group 501 to a focus position.
  • the focus position When the focus position is detected by such a phase difference method, the focus position can be detected at a relatively high speed, and high-speed autofocus can be realized.
  • the imaging pixel and the phase difference detection pixel are mixedly formed. In order to improve the respective pixel characteristics, for example, it is necessary to optimize the focal length of the microlens corresponding to each pixel.
  • 20A and 20B represent imaging pixels having different curvatures
  • C in FIG. 20 and D in FIG. 20 represent phase difference detection pixels having different curvatures.
  • the imaging pixels shown in FIG. 20A and FIG. 20B are above the photodiode 513, have light shielding films 512 at both ends of the photodiode 513, and receive light incident on the microlens 511.
  • phase difference detection pixels shown in FIG. 20C and FIG. 20D are above the photodiode 513, and are provided with light shielding films 512 at both ends of the photodiode 513, respectively, and one light shielding film is the photodiode 513.
  • the light incident on the microlens 511 is received through the opened portion.
  • a line indicated by an arrow represents light, and represents light that is incident on the photodiode 513 through the microlens 511. Further, the curvature of the imaging pixel shown in A of FIG. 20 is the same as that of the phase difference detection pixel shown in C of FIG. 20, and the curvature of the imaging pixel shown in B of FIG. The curvature of the phase difference detection pixels indicated by 20D is the same.
  • the imaging pixel shown in FIG. 20A shows a case where the curvature radius of the microlens 511 is large
  • the imaging pixel shown in FIG. 20B shows a case where the curvature radius of the microlens 511 is small.
  • FIG. 20A in the case of an imaging pixel, if the radius of curvature of the microlens 511 is large, light is easily collected on the photodiode 513, and the light receiving sensitivity is increased.
  • the phase difference detection pixel when the radius of curvature of the microlens 511 is large, the light is condensed on the photodiode 513, but the light incident from the left side and the light incident from the right side are collected. The added light adds an opening and is collected. That is, in this case, there is a possibility that the decomposing ability is lowered.
  • the optimal curvature radius of the microlens 511 of the imaging pixel and the optimal curvature radius of the microlens 511 of the phase difference detection pixel are different.
  • the radius of curvature of the microlens 511 is configured so that both the imaging pixels and the phase difference detection pixels have an appropriate focal length as much as possible. .
  • the layer thickness from the microlens 511 to the photodiode 513 is thin, and the focal position is preferably on the side of the photodiode 513 including the light shielding film 512.
  • the focal length of the phase difference detection pixel is preferably on the light shielding film 512 side.
  • the radius of curvature radius of the microlens 511 formed in the phase difference detection pixel is closer to 1.0, the phase difference from the two directions of the subject is separated. Since the noise component at the time is reduced, the separation characteristics are improved.
  • FIG. 21A shows a case where one phase difference detection pixel is viewed from above.
  • a square at the center represents one pixel, and a microlens 511 is formed in the one pixel.
  • an area ratio of one pixel in a plan view and an area ratio of the microlens 511 is 80% or more.
  • FIG. 21A a cross section when the phase difference detection pixel is cut in the horizontal direction aa ′ is shown in FIG. 21B, and a cross section when the phase difference detection pixel is cut in the oblique direction bb ′.
  • 21 C. 21B and 21C the radius of curvature of the microlens 511 decreases in the horizontal direction of the phase difference detection pixel, but the radius of curvature of the microlens 511 increases in the oblique direction. . This is because the length of the bottom surface of the micro lens is different (horizontal direction a-a ' ⁇ oblique direction b-b').
  • r1 represents the radius of curvature of the microlens 511 in the horizontal direction
  • r2 represents the radius of curvature of the microlens 511 in the oblique direction.
  • the curvature radius r1 is smaller than the curvature radius r2.
  • the curvature flatness As the curvature flatness is closer to 1.0, the noise component when separating the phase difference from the two directions of the subject decreases, and the separation characteristic of the phase difference detection pixel improves.
  • This curvature flatness depends on the pixel size. An example of the relationship between the curvature flatness and the pixel size is shown in FIG.
  • the vertical axis represents the ratio of curvature radii (curvature flatness), and the horizontal axis represents the unit pixel size (the length of one side of the unit pixel).
  • FIG. 22 shows that the curvature flatness is 1.2 or less when the pixel size is 3 ⁇ m or less. As described above, the closer the curvature flatness is to 1.0, the better the separation characteristics, but until about 1.2, it is known that the separation characteristics will not be significantly reduced.
  • the micro lens 511 may be configured as follows.
  • the unit pixel size is preferably 3 ⁇ m or less.
  • the pixel size in such an imaging device is generally about 3 to 6 ⁇ m.
  • the curvature flatness of the phase difference detection pixel is 1.6 or more, for example, referring to FIG. 22, and the separation capability is likely to be reduced. Therefore, there is a possibility that it is not suitable for an image pickup apparatus having a large pixel size if the autofocus by the phase difference method is used.
  • the size of the microlens is 1.5 ⁇ m, which is smaller than 3 ⁇ m, so the curvature flatness is 1.2 or less.
  • the curvature flatness is a value close to 1.0.
  • the present technology it is possible to provide a plurality of microlenses on a unit pixel, and it is possible to reduce the size of one microlens by providing a plurality of microlenses. Become. By reducing the size of the microlens, the curvature flatness becomes a value close to 1.0 as described above, and the performance as a phase difference detection pixel can be improved.
  • the light shielding film of the phase difference detection pixel when a plurality of microlenses are provided on the unit pixel will be described.
  • FIG. 8B a case where four microlenses are provided in a unit pixel will be described as an example.
  • the present technology relating to the light shielding film described below can be applied to other numbers of microlenses such as nine or sixteen.
  • FIG. 23 is a diagram showing an example of the shape of the light shielding film when four microlenses are provided on a unit pixel.
  • the light shielding film shown in FIG. 23 is a case where light information from one direction is received, and FIG. 23 shows the shape of the light shielding film when light information from the right side is received.
  • microlenses 511-1 to 511-4 are referred to as microlenses 511-1 to 511-4, respectively.
  • FIG. 24 shows a cross-sectional view of the phase difference detection pixel having the light shielding film 512 shown in FIG.
  • the phase difference detection pixel shown in FIG. 24 is a cross-sectional view of the microlens 511-2 and the microlens 511-3 shown in FIG.
  • the light shielding film 512 is continuously provided between adjacent pixels. That is, a quadrangular portion representing a unit pixel indicated by a dotted line in the drawing is a boundary portion between adjacent pixels, and a light shielding film 512 is provided in such a portion.
  • a light shielding film 512 is provided so as to cover up to the central portion of the two microlenses 511 arranged in the vertical direction.
  • a light shielding film 512-1 is provided from the right side to the center of the microlenses 511-1 and microlenses 511-2 arranged in the vertical direction.
  • a light shielding film 512-2 is provided from the right side to the center of the microlenses 511-3 and 511-4 arranged in the vertical direction.
  • the light shielding film positioned on the right side of the photodiode 513 is configured to have a wide width and configured to have an opening on the left side.
  • a light shielding film is provided for each microlens 511.
  • a light shielding film 512 at the boundary between the four microlenses 511-1 to 511-4 provided in the unit pixel.
  • a light shielding film 512 is also provided between the microlens 511-1 and the microlens 511-2 and between the microlens 511-3 and the microlens 511-4. Yes.
  • the light shielding film 512 is provided so as to surround one microlens 511, and one of the sides is configured to be larger than the other side, whereby the opening with respect to the photodiode 513 is reduced, and the direction from a predetermined direction is reduced.
  • a structure that can selectively receive light may be used.
  • a plurality of microlenses 511 and a plurality of light shielding films 512 may be provided on one photodiode 513, or a plurality of microlenses may be provided as shown in FIG.
  • a plurality of photodiodes 513 may be configured in accordance with 511.
  • the unit pixel here is an area having the same size as the imaging pixel. It is assumed that it is a pixel inside.
  • FIG. 25 is a cross-sectional view and a plan view of a phase difference detection pixel when a photodiode 513 is formed in accordance with the microlens 511.
  • the microlens 511-2 and the microlens 511-3 are arranged side by side to detect the phase difference.
  • a light shielding film 512-1 and a light shielding film 512-2 are provided for functioning as pixels for use.
  • a photodiode 513-1 that receives light from the microlens 511-2 and a photodiode 513-2 that receives light from the microlens 511-3 are provided. ing.
  • the photodiode 513-1 and the photodiode 513-2 correspond to the photodiode configured as one photodiode 513 in the phase difference detection pixel shown in FIG.
  • the photodiode 513-1 is disposed below the microlens 511-1 and the microlens 511-2, and is placed on the right side through the microlens 511-1 and the microlens 511-2. It is configured to receive light incident from the direction.
  • the photodiode 513-2 is arranged below the microlens 511-3 and the microlens 511-4, and the microlens 511-3 and the microlens 511-4 are connected to each other. It is comprised so that the light which injected from the right direction through may be received.
  • two photodiodes 513-1 and 513-2 are provided in a region where one unit pixel is provided, and a light shielding film 512 for functioning as a phase difference detection pixel on each photodiode 513. -1 and the light shielding film 512-2 may be provided.
  • phase difference detection pixel that receives light incident from the right direction and extracts light information from the right direction is shown.
  • a phase difference detection pixel including a photodiode 513 that receives incident light and a photodiode 513 that receives light incident from the left direction.
  • FIG. 26 shows the phase difference detection pixel in the case where two photodiodes 513-1 and photodiodes 513-2 that receive light from the left and right directions are provided in one unit pixel. It is a figure which shows a structure.
  • phase difference detection pixel shown in FIG. 26A In the cross section of the phase difference detection pixel shown in FIG. 26A, as with the phase difference detection pixel shown in FIG. 25A, the microlens 511-2 and the microlens 511-3 are arranged side by side. .
  • a light shielding film 512-2 for functioning as a phase difference detection pixel is disposed between the photodiode 513-1 and the photodiode 513-2. .
  • the light-shielding film 512-2 is provided at the center portion in the unit pixel, covers the photodiode 513-2 from the left side to the center portion, and from the right side of the photodiode 513-2 to the center. It is continuously configured to cover up to the part.
  • the photodiode 513-2 is configured with the right half opened
  • the photodiode 513-3 is configured with the left half opened.
  • the photodiode 513-1 is disposed below the microlens 511-1 and the microlens 511-2, and moves to the left via the microlens 511-1 and the microlens 511-2. It is comprised so that the light which injected from may be received.
  • the photodiode 513-2 is arranged below the microlens 511-3 and the microlens 511-4 as shown in FIG. 26B, and is interposed via the microlens 511-3 and the microlens 511-4. And configured to receive light incident from the right direction.
  • two photodiodes 513-1 and 513-2 are provided in a region where one unit pixel is provided, and a light shielding film 512 for functioning as a phase difference detection pixel on each photodiode 513. It is good also as a structure which provides. In addition, when configured in this way, light information from different directions can be acquired by one unit pixel, and therefore, a configuration in which a phase difference is detected only by this unit pixel can be employed.
  • the photodiodes 513 are provided in the left-right direction (horizontal direction) when the phase difference detection pixel is viewed in plan from above is described as an example. However, as shown in FIG.
  • the photodiodes 513 may be provided in the vertical direction (vertical direction).
  • FIG. 27 shows a phase difference detection pixel when two photodiodes 513-1 and 513-2 for receiving light from the left and right directions are provided in one unit pixel. It is a figure which shows a structure.
  • the microlens 511-1 and the microlens 511-4 are arranged side by side.
  • a light shielding film 512-1 and a light shielding film 512-2 for functioning as a phase difference detection pixel are arranged.
  • the light shielding film 512-1 is configured to cover from the right side to the central part of the microlens 511-1, and the light shielding film 512-2 is configured to cover from the right side to the central part of the microlens 511-2.
  • the left half of the microlens 511-1 is open and the left half of the microlens 511-4 is open.
  • the microlens 511-2 and the microlens 511-3 are arranged side by side.
  • a light shielding film 512-5 and a light shielding film 512-6 for functioning as a phase difference detection pixel are arranged.
  • the light shielding film 512-5 is configured to cover from the left side of the microlens 511-2 to the central portion
  • the light shielding film 512-6 is configured to cover from the left side of the microlens 511-3 to the central portion.
  • the right half of the microlens 511-2 is configured to be opened, and the right half of the microlens 511-3 is configured to be opened.
  • the photodiode 513-1 is arranged below the microlens 511-1 and the microlens 511-4 arranged side by side, and the microlens 511-1 and the microlens 511- 4 is configured to receive light incident from the right via 4.
  • the photodiode 513-2 is disposed below the microlens 511-2 and the microlens 511-3 as shown in FIG. 27C, and is interposed via the microlens 511-2 and the microlens 511-3. It is configured to receive light incident from the left direction.
  • two photodiodes 513-1 and 513-2 are provided in a region where one unit pixel is provided, and a light shielding film 512 for functioning as a phase difference detection pixel on each photodiode 513. It is good also as a structure which provides. Further, when configured in this way, light information from different directions can be acquired by one unit pixel, and therefore, it is possible to adopt a configuration in which a phase difference is detected by this unit pixel.
  • FIG. 28 is a diagram showing a cross section of a phase difference detection pixel when a light shielding film is provided in the vertical direction.
  • the light shielding film in the vertical direction is described as a light shielding wall.
  • phase difference detection pixel will be described as an example, but an example in which one microlens is provided in one photodiode will be described, but a plurality of microlenses are provided.
  • the imaging pixel can be provided with a light shielding wall described below.
  • the light shielding wall is provided on the light shielding film 512 as shown in FIG.
  • the light shielding film 512-1 is provided up to the center of the photodiode 513 and is provided as a film for functioning as the phase difference detection pixel.
  • a light shielding wall 551-1 is provided on the light shielding film 512-1.
  • a light shielding wall 551-2 is provided on the light shielding film 512-2.
  • the light shielding wall 551-1 is provided in a direction perpendicular to the light shielding film 512-1
  • the light shielding wall 551-2 is provided in a direction perpendicular to the light shielding film 512-2.
  • the example in which the light shielding wall 551 is provided on the light shielding film 512 (on the microlens 511 side) is shown, but the light shielding wall 551 may be provided below the light shielding film 512 (on the photodiode 513 side).
  • the light shielding film 512 and the light shielding wall 551 are illustrated as lines, but the light shielding film 512 and the light shielding wall 551 are formed as a film (wall) having a predetermined thickness and size.
  • FIG. 29 is a diagram of a phase difference detection pixel having a light shielding wall as viewed from the microlens 511 side.
  • the shaded film 512 indicates the light shielding film 512
  • the light shielding wall 551 is outlined on the light shielding film 512.
  • the light shielding wall 551-2 provided on the light shielding film 512-2 is formed in a quadrangular shape.
  • the light shielding wall 551-2 is provided so that stray light components from adjacent pixels do not enter.
  • the light shielding wall 551-1 provided on the light shielding film 512-1 has a curved shape.
  • the light shielding wall 551-1 has a curved shape, for example, a circular arc, and has a shape in which the inner side of the circular arc faces the opening.
  • the light-shielding wall 551-1 is provided so that stray light components from adjacent pixels do not enter, and is provided so that light is easily collected at the opening by reflecting incident light. .
  • the phase difference detection pixel is provided with the light-shielding film 512, so that the opening portion is configured to be small. Therefore, the sensitivity is lower than that of the imaging pixel. In order to improve the sensitivity of the phase difference detection pixel, it is conceivable to increase the amount of light incident on the photodiode 513 through the opening.
  • the light shielding wall 551-1 is curved, and the light reflected by the light shielding wall 551-1 is collected on the opening side.
  • the configuration is as follows.
  • Such a light shielding wall may be continuously formed so as to surround the opening as shown in FIG. 30, for example.
  • the light shielding wall 551 shown in FIG. 30 is formed so as to surround the photodiode 513 similarly to the light shielding film 512.
  • the portion provided on the light shielding film 512-1 provided for functioning as a phase difference detection pixel is formed in a curved shape, but other portions are provided. Is formed in a straight line shape like the light shielding film 512.
  • the light shielding wall 551 provided in a linear shape may also be formed in a shape capable of condensing light with respect to the opening.
  • phase difference detection pixel has been described as an example, but a configuration in which a light-shielding wall is provided also for the imaging pixel can be employed. Even when a light-shielding wall is provided on the imaging pixel, the stray light component from the adjacent pixel can be shielded as in the case of the phase difference detection pixel described above, and the light collecting performance is improved by reflecting the incident light. It can also be improved.
  • phase difference detection pixel and imaging pixel are arranged on the same imaging surface.
  • FIG. 31 is a diagram illustrating a pixel when both a phase difference detection pixel and an imaging pixel are configured by microlenses having the same size.
  • four microlenses are formed on one unit pixel in both the phase difference detection pixel and the imaging pixel.
  • the pixel located at the center is the phase difference detection pixel 602, and the surrounding pixels are the imaging pixels 601-1 to 601-8.
  • the gap generated at the corner portion between the microlenses can be reduced.
  • FIG. 32 shows an example in which the phase difference detection pixel 612 is arranged at the center and the imaging pixel 611 is arranged around the center, as in the example shown in FIG.
  • the imaging pixel 611 has one microlens formed in the unit pixel
  • the phase difference detection pixel 612 has four microlenses formed in the unit pixel. .
  • the number of microlenses provided in the imaging pixel 611 and the phase difference detection pixel 612 is different, in other words, the size of the microlens provided in the imaging pixel 611 and the phase difference detection pixel 612, respectively. It is also possible to configure the lengths to be different.
  • the gap generated at the corner portion between the imaging pixel 611 and the phase difference detection pixel 612 becomes large, but the effect of the gap is reduced by providing a step of filling the gap. Is possible.
  • the imaging pixel 611 includes one microlens and the phase difference detection pixel 612 includes an example including four microlenses.
  • the pixel 611 may include a plurality of microlenses, and the phase difference detection pixel 612 may include one microlens.
  • the present technology can be applied to pixels for realizing phase difference autofocus.
  • the present technology is not limited to application to an image sensor, but an image sensor such as a digital still camera or a video camera, a portable terminal device having an image capture function such as a cellular phone, or a copy using an image sensor for an image reading unit.
  • the present invention can be applied to all electronic devices that use an image sensor in an image capturing unit (photoelectric conversion unit) such as a computer.
  • a module-like form mounted on an electronic device that is, a camera module is used as an imaging device.
  • FIG. 33 is a block diagram illustrating a configuration example of an image sensor that is an example of the electronic apparatus of the present disclosure.
  • an imaging apparatus 1000 includes an optical system including a lens group 1001 and the like, an imaging element 1002, a DSP circuit 1003 that is a camera signal processing unit, a frame memory 1004, a display device 1005, a recording device 1006, An operation system 1007, a power supply system 1008, and the like are included.
  • the DSP circuit 1003, the frame memory 1004, the display device 1005, the recording device 1006, the operation system 1007, and the power supply system 1008 are connected to each other via the bus line 1009.
  • the CPU 1010 controls each unit in the imaging apparatus 1000.
  • the lens group 1001 takes in incident light (image light) from a subject and forms an image on the imaging surface of the imaging element 1002.
  • the imaging element 1002 converts the amount of incident light imaged on the imaging surface by the lens group 1001 into an electrical signal in units of pixels and outputs it as a pixel signal.
  • the image sensor 1002 the image sensor according to the above-described embodiment can be used.
  • the display device 1005 includes a panel display device such as a liquid crystal display device or an organic EL (electroluminescence) display device, and displays a moving image or a still image captured by the image sensor 1002.
  • the recording device 1006 records a moving image or a still image captured by the image sensor 1002 on a recording medium such as a video tape or a DVD (Digital Versatile Disk).
  • the operation system 1007 issues operation commands for various functions of the imaging device under the operation of the user.
  • the power source system 1008 appropriately supplies various power sources serving as operation power sources for the DSP circuit 1003, the frame memory 1004, the display device 1005, the recording device 1006, and the operation system 1007 to these supply targets.
  • Such an imaging apparatus 1000 is applied to a video camera, a digital still camera, and a camera module for a mobile device such as a mobile phone.
  • the imaging element according to the above-described embodiment can be used as the imaging element 1002.
  • system represents the entire apparatus composed of a plurality of apparatuses.
  • this technology can also take the following structures.
  • An inner lens is further provided between the microlens and the photodiode, The inner lens collects the principal ray of at least one of the plurality of condensing spots collected by the plurality of microlenses toward the unit pixel center direction.
  • the imaging element is a pixel for detecting a focal point by detecting a phase difference.
  • the microlens is a manufacturing apparatus that manufactures an image pickup device in which each unit pixel has a substantially square shape with a side of less than 1.98 ⁇ m and is a square of two or more natural numbers.
  • An electronic device comprising: a signal processing unit that performs signal processing on a signal output from the imaging element.

Abstract

La présente technologie se rapporte à un élément de formation d'image qui, même lorsque la taille des pixels est importante, permet de réduire le mélange optique des couleurs et les reflets, un dispositif de fabrication et un dispositif électronique. Un élément de formation d'image comprend une pluralité de pixels élémentaires formés dans une région réceptrice de lumière, un film opaque à la lumière formé dans une région frontière entre les pixels élémentaires et une microlentille formée pour chacun des pixels élémentaires. Le pixel élémentaire est un réseau approximativement carré de 1,98 µm ou plus, les microlentilles, qui sont approximativement carrées et ont chacune un côté inférieur à 1,98 µm et dont le nombre est égal au carré d'un entier naturel supérieur ou égal à 2, étant formées pour chacun des pixels élémentaires. Le film opaque à la lumière est en outre formé dans une région frontière entre les microlentilles. La présente technologie peut s'appliquer à un dispositif de formation d'image ayant une taille de pixel importante.
PCT/JP2015/052797 2014-02-13 2015-02-02 Élément de formation d'image, dispositif de fabrication et dispositif électronique WO2015122300A1 (fr)

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