JP2008103472A - Solid-state imaging element and imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging element and an imaging device employing the element which suppresses the leakage of light from a neighbored or near pixel into an OPB pixel to prevent the deviation of black level and which is capable of obtaining the image signal of high image quality. <P>SOLUTION: An invalid pixel region 33, neighbored to an effective OPB pixel region 35, is provided in the circumference of an effective pixel region 32 in the solid-state imaging element 30 and a plurality of layers of wirings 47, 48, 49 in the invalid pixel region 33 are constituted so as to be arranged so that an opening 54c for receiving light in the invalid pixel region 33 is extended from a photo diode PD toward an on-chip lens 52 in a direction orthogonal to the photo diode PD. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device capable of suppressing light leakage to an optical black pixel that extracts an optical black signal that serves as a reference for a black level in a CCD or CMOS image sensor, and an imaging device using the same. About.

  In recent years, in solid-state imaging devices such as CCD and CMOS image sensors, miniaturization of the device itself and higher density of pixels have progressed, and accordingly, sensitivity reduction due to reduction of an imaging area in which pixels are two-dimensionally arranged on a matrix. This causes deterioration of characteristics. As a countermeasure against this sensitivity reduction, an on-chip lens is provided for each light receiving portion (pixel) on the imaging surface of the solid-state image pickup device, and the light collection efficiency of each light receiving portion is increased by the light collecting action of this on-chip lens. (See Patent Document 1).

The configuration of the imaging surface of the CMOS solid-state imaging device will be described with reference to FIG.
On the imaging surface 2 of the solid-state imaging device 1 shown in FIG. 4, an effective pixel area 2a that uses a pixel signal as actual imaging information, and an invalidity that is located on the outer periphery of the effective pixel area 2a and invalidates the pixel signal at that position A pixel area 2b, an invalid OPB (optical black) pixel area 2c that is located on the outer periphery of the invalid pixel area 2b and invalidates the pixel signal at the position, and a pixel signal that is located on the outer circumference of the invalid OPB pixel area 2c An effective OPB pixel area (optical black area) 2d using as the actual OPB (optical black) information, a dummy pixel area 2e located on the outer periphery of the effective OPB pixel area 2d and having a pixel signal at the position as a dummy, A peripheral circuit formation region 2f exists.
By providing the effective OPB pixel region 2d in this way and taking the black level that is each pixel signal in the effective OPB pixel region 2d as a reference, by taking the difference between this reference signal and each pixel signal in the effective pixel region 2a, A noise component that is thermally generated in a state where no light is incident, that is, a so-called dark current can be removed. This makes it possible to improve the image quality of the video signal. The invalid OPB pixel region 2c and the effective OPB pixel region 2d are shielded from light by a light shielding film made of metal such as aluminum.

  In a solid-state imaging device incorporated in an imaging device such as a digital camera, an optical system such as a lens is used to form a captured image on the imaging surface. In this case, the incident angle of light passing through the optical system changes. In particular, the incident angle of light differs between the center of the field angle and the periphery of the imaging surface. That is, as shown in FIG. 5, the principal ray 5 passing through the center of the camera lens 4 is imaged in the center of the imaging surface 2 of the solid-state imaging device 1, but the peripheral ray 6 is imaged in the peripheral region of the imaging surface. And the incident angle of the light with respect to an imaging surface becomes large as it goes to the periphery from the center of the imaging surface 2. FIG. Furthermore, when the exit pupil distance from the imaging surface of the solid-state imaging device to the exit pupil is short and the F value is small, the incident angle of the ambient light is further increased. For example, when a camera lens having an F value of about 1.8 is used, the incident angle of ambient light is 35 degrees.

On the other hand, when the incident angle of light with respect to the imaging surface of the solid-state imaging device increases from the center of the imaging surface to the periphery, the light collection efficiency by the on-chip lens of each pixel toward the periphery of the imaging surface increases. The sensitivity is lowered.
Therefore, an element structure of a pixel and a pixel structure of a pixel in an effective OPB pixel area for equalizing the light collection efficiency to the light receiving unit by the on-chip lens in the effective pixel area of the conventional imaging surface will be described with reference to FIG. To do.

FIG. 6A shows an element structure of a pixel located in the center of the effective pixel region 2a shown in FIG. 4, and a photodiode PD is formed on the surface layer portion of the silicon substrate 10 and a floating region is formed in the vicinity thereof. A diffusion portion FD is formed. Further, the gate electrode 13 of the transfer transistor 12 is formed on the surface of the silicon substrate 10 above the channel region between the photodiode PD and the floating diffusion portion FD via the gate insulating film 11. The photodiode PD and the transfer transistor 12 are individually separated by an element isolation layer (LOCOS) 14 for each pixel. Furthermore, on the surface of the silicon substrate 10, metal wirings 16, 17, and 18 are provided in three layers via an interlayer insulating layer 15, and the color filter 20 and the metal wirings 16, 17 and 18 are provided thereon via a planarization film (passivation film) or the like. An on-chip lens 21 is arranged.
Further, the on-chip lens 21 of the pixel located at the center of the effective pixel region 2a is arranged with the optical axis coincident with the axis of the light ray 22a having an incident angle of 0 degrees, and the metal wirings 16, 17, and 18 are the light rays 22a Is disposed via an interlayer insulating layer 15 in a direction perpendicular to the axis of The metal wirings 16, 17, and 18 provided above the photodiode PD maintain the light receiving opening 23a for guiding the light beam 22a collected by the on-chip lens 21 to the photodiode PD. They are arranged in a direction orthogonal to the photodiode PD.

FIG. 6B shows the element structure of the pixel located on the outer periphery of the effective pixel region 2a shown in FIG. 4, and is formed on the surface layer portion of the silicon substrate 10 in the same manner as the element structure of the pixel in the effective pixel region 2a. A floating diffusion portion FD is formed in the vicinity thereof, and gate insulation is provided above the channel region between the photodiode PD and the floating diffusion portion FD on the surface of the silicon substrate 10. A gate electrode 13 of the transfer transistor 12 is formed through the film 11. The photodiode PD and the transfer transistor 12 are individually separated by the element isolation layer 14 for each pixel. On the surface of the silicon substrate 10, metal wirings 16, 17, and 18 are provided in three layers via an interlayer insulating layer 15, and a color filter 20 and an on-chip lens 21 are provided thereon via a planarizing film or the like. Is arranged.
Further, the on-chip lenses 21 of the pixels located around the effective pixel region 2a are arranged so as to be shifted toward the center of the effective pixel region 2a corresponding to the incident angle of the inclined light ray 22b. The metal wirings 16, 17, and 18 provided above the photodiode PD maintain the light receiving opening 23b for guiding the light beam 22b collected by the on-chip lens 21 to the photodiode PD. Along the inclined light ray 22b, the photodiodes PD are arranged so as to be shifted toward the color filter 20 in a direction approaching the center of the effective pixel region 2a.
Note that the incident angle of the light beam 22b in the effective pixel region 2a increases with increasing distance from the center of the effective pixel region 2a to the outer periphery.

FIG. 6C shows the element structure of the pixel located in the invalid pixel area 2b shown in FIG. 4, and is formed on the surface layer portion of the silicon substrate 10 in the same manner as the element structure of the pixel in the effective pixel area 2a. A floating diffusion portion FD is formed in the vicinity of the photodiode PD, and the gate insulating film 11 is disposed above the channel region between the photodiode PD and the floating diffusion portion FD on the surface of the silicon substrate 10. A gate electrode 13 of the transfer transistor 12 is formed via the. The photodiode PD and the transfer transistor 12 are individually separated by the element isolation layer 14 for each pixel. On the surface of the silicon substrate 10, metal wirings 16, 17, and 18 are provided in three layers via an interlayer insulating layer 15, and a color filter 20 and an on-chip lens 21 are provided thereon via a planarizing film or the like. Is arranged.
Further, the on-chip lens 21 of the pixel located in the invalid pixel region 2b is arranged so as to be shifted in a direction approaching the center of the effective pixel region 2a corresponding to the incident angle of the inclined light ray 22c. The metal wirings 16, 17, and 18 provided above the photodiode PD maintain the light receiving opening 23a for guiding the light beam 22a collected by the on-chip lens 21 to the photodiode PD. The light beams 22c are arranged along the inclined light rays 22c so as to be shifted from the photodiode PD toward the color filter 20 in a direction approaching the center of the effective pixel region 2a.

FIG. 6D shows the element structure of the pixel located in the effective OPB pixel area 2d shown in FIG. 4, and is formed on the surface layer portion of the silicon substrate 10 in the same manner as the element structure of the pixel in the effective pixel area 2a. A floating diffusion portion FD is formed in the vicinity thereof, and a gate insulating film is formed above the channel region between the photodiode PD and the floating diffusion portion FD on the surface of the silicon substrate 10. A gate electrode 13 of the transfer transistor 12 is formed via 11. The photodiode PD and the transfer transistor 12 are individually separated by the element isolation layer 14 for each pixel. Further, on the surface of the silicon substrate 10, metal wirings 16 and 17 and a metal wiring 18 serving as a light shielding film are provided in three layers via an interlayer insulating layer 15, and a planarizing film 19 and the like are provided thereon. A color filter 20 is disposed. Further, the metal wirings 16, 17, and 18 provided above the photodiode PD are arranged so as to be shifted toward the center of the effective pixel region 2a as they go upward from the photodiode PD. The photodiode PD in the effective OPB pixel region 2d is shielded by the metal wiring 18 that also serves as a light shielding film so that light transmitted through the camera lens is not incident.
JP-A-11-103036

In such a conventional solid-state imaging device, as shown in FIG. 6C, a part of the light beam 22c incident on the photodiode PD through the on-chip lens 21 of the pixel in the invalid pixel region 2b is made of the metal wirings 16 and 17. , 18, and a part of the light 22c1 that is diffusely reflected is incident on the adjacent effective OPB pixel region 2d, and the light beam 22c2 reflected by the metal wirings 16, 17, 18 in the effective OPB pixel region 2d is shown in FIG. As shown in FIG. 6D, the light reaches the photodiode PD in the effective OPB pixel region 2d and undergoes photoelectric conversion. As a result, signal charges other than the dark current component are generated, and the black level reference is distorted.
In this way, when the black level reference is violated, the pixel signal of the effective OPB pixel region 2d is lower in level than the pixel signal of the effective pixel region 2a. The captured image in this state appears to have a black stripe running on a part thereof, resulting in an unnatural image and a reduction in image quality.

One of the factors that cause light to leak from the invalid pixel area 2b into the pixels of the effective OPB pixel area 2d is to reduce the pixel size. That is, by using the fine processing technology used in the manufacture of semiconductor devices, it becomes possible to perform fine line processing such as metal wiring of a solid-state image pickup device, and it is possible to reduce the pixel size. Technology miniaturization may not be directly proportional, and as a result, the proportion of openings in the effective pixel region 2a is reduced when the pixel size is miniaturized. For this reason, the ratio of the light irradiated to the imaging surface of the solid-state imaging device is reflected by the metal wiring in proportion to the miniaturization of the pixel size.
In addition, since the incident angle of light is different between the center and the periphery of the imaging surface in the solid-state imaging device, the position of the on-chip lens is shifted so that the incident light is focused on the photodiode, and the on-chip lens is focused. The wiring pattern is laid out so that the transmitted light can pass through the opening of the metal wiring.
However, since the incident angle of the light collected by the camera lens on the imaging surface of the solid-state imaging device increases from the center of the imaging surface to the periphery, the light collected by the on-chip lens for each pixel Most of the light reaches the photodiode through the opening, but the proportion of the light reflected by the metal wiring increases in proportion to the increase in the incident angle of the light, resulting in the black reference output from the effective OPB pixel. There was a problem that the signal deteriorated and the image deteriorated.

  The present invention has been made to solve the above-described problems, and its purpose is to prevent the black level from being distorted by suppressing light leakage from adjacent or neighboring pixels to the OPB pixel. An object of the present invention is to provide a solid-state imaging device capable of obtaining a high-quality image signal and an imaging device using the same.

  In order to achieve the above object, in a solid-state imaging device according to the present invention, a plurality of pixels including a photoelectric conversion element and a gate element are arranged in a two-dimensional array on a semiconductor substrate, and the signal of the pixel is used as an effective pixel signal. An invalid pixel in which a plurality of pixels including a photoelectric conversion element and a gate element are arranged on the semiconductor substrate and arranged on the outer periphery of the effective pixel area, and the signal of the pixel is an invalid pixel signal that is not valid An optical black in which a plurality of pixels including a photoelectric conversion element and a gate element are arranged on the semiconductor substrate in a state of being shielded from light, and a signal of the pixel is used as a black level reference. The pixel arrangement and the light receiving opening for guiding the imaging light beam for each photoelectric conversion element of each pixel are secured on the semiconductor substrate of the pixel area. Wiring provided in a plurality of layers with an insulating layer in the direction and the wiring including the insulating layer in the effective pixel region arranged for each pixel above the imaging light beam to the photoelectric conversion element and the light receiving opening A first on-chip lens that condenses through the unit, and is arranged for each pixel above the wiring including the insulating layer in the invalid pixel region, and condenses the imaging light beam through the light receiving opening through the photoelectric conversion element. A second on-chip lens that corresponds to an incident angle of the imaging light beam to the effective pixel region that increases with increasing distance from the center to the periphery of the effective pixel region. The pixels in the effective pixel region are arranged so as to be shifted in a direction approaching the central portion of the effective pixel region, and the plurality of layers of wiring in the effective pixel region have the light receiving openings maintained therein. The plurality of layers of wiring in the invalid pixel region are arranged in a direction approaching the center of the effective pixel region from the electrical conversion element toward the first on-chip lens in correspondence with the incident angle of the imaging light beam. The light receiving opening of the invalid pixel region is arranged so as to extend in a direction orthogonal to the photoelectric conversion element from the photoelectric conversion element toward the second on-chip lens.

  The image pickup apparatus of the present invention includes a solid-state image pickup device, an optical system that guides incident light from a subject to the solid-state image pickup device, and a signal processing circuit that processes an output signal from the solid-state image pickup device. The imaging element includes an effective pixel area in which a plurality of pixels including a photoelectric conversion element and a gate element are arranged in a two-dimensional array on a semiconductor substrate, and a signal of the pixel is used as an effective pixel signal, and an outer periphery of the effective pixel area. A plurality of pixels including a photoelectric conversion element and a gate element are arranged on the semiconductor substrate and an invalid pixel region in which the signal of the pixel is an invalid pixel signal is not valid, and is positioned on the outer periphery of the invalid pixel region An optical black pixel region in which a plurality of pixels including a photoelectric conversion element and a gate element are arranged in a light-shielded state on the semiconductor substrate, and a signal of the pixel is used as a black level reference; Provided in a plurality of layers through an insulating layer in the pixel array direction so that a light receiving opening for guiding the imaging light beam for each photoelectric conversion element of each pixel is secured on the semiconductor substrate in the pixel region. A first on-chip lens that is disposed for each pixel above the wiring including the insulating layer in the effective pixel region and collects the imaging light beam on the photoelectric conversion element through the light receiving opening, A second on-chip lens that is disposed for each pixel above the wiring including the insulating layer in the invalid pixel region and collects the imaging light beam on the photoelectric conversion element through the light receiving opening. One on-chip lens corresponds to the effective pixel area for each pixel in the effective pixel area corresponding to the incident angle of the imaging light beam to the effective pixel area that increases as it goes from the center to the periphery of the effective pixel area. The plurality of layers of wiring in the effective pixel region are arranged so as to approach the center of the elementary region, and the light receiving opening is maintained from the photoelectric conversion element toward the first on-chip lens. The multiple layers of wiring in the invalid pixel region are arranged in a direction approaching the center of the effective pixel region in accordance with the incident angle of the imaging light beam, and are directed from the photoelectric conversion element to the second on-chip lens. The light receiving opening of the invalid pixel region is arranged so as to extend in a direction orthogonal to the photoelectric conversion element.

  According to the solid-state imaging device and the imaging apparatus according to the present invention, the invalid pixel region adjacent to the optical black pixel region is provided around the effective pixel region, and the plurality of layers of wiring in the invalid pixel region are connected to the second from the photoelectric conversion device. Since the light receiving opening in the invalid pixel area is arranged so as to extend in a direction orthogonal to the photoelectric conversion element toward the on-chip lens, even if incident light is irregularly reflected by the wiring in the invalid pixel area Therefore, it is possible to prevent or suppress the irregular reflection light from leaking into the optical black pixel in the optical black pixel region, thereby preventing the black level from being distorted and obtaining a high-quality image signal.

(Embodiment 1)
Hereinafter, a solid-state imaging device and an imaging apparatus using the same according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a solid-state imaging device including an effective pixel region and an OPB pixel region in Embodiment 1 of the present invention, and FIG. 2 shows an element structure of an image in each pixel region of the solid-state imaging device in Embodiment 1. FIG. 3 is a block diagram showing the overall configuration of the imaging apparatus using the solid-state imaging device shown in the first embodiment.

  On the imaging surface 31 of the solid-state imaging device 30 shown in FIG. 1, an effective pixel region 32 in which a plurality of pixels are arranged in a two-dimensional array and signals of the pixels are used as effective pixel signals, and the effective pixel region 32. An invalid pixel region 33 in which a plurality of pixels are arranged at the outer periphery of the pixel and an invalid pixel signal in which the signal of the pixel is not valid, and a plurality of pixels are arranged at the outer periphery of the invalid pixel region 33 An invalid OPB (optical black) pixel region 34 in which the pixel signal is an invalid pixel signal that is not valid, and a plurality of pixels are arranged in a state of being shielded from light and located on the outer periphery of the invalid OPB pixel region 34. An effective OPB pixel area (optical black area) 35 in which a pixel signal is used as a black level reference (OPB information), and a plurality of pixels are arranged on the outer periphery of the effective OPB pixel area 35 to display the image. A dummy pixel region 36 to which a signal is a dummy, there is a peripheral circuit formation region 37.

  A pixel 321 located in the center of the effective pixel region 32 includes a pixel having an element structure shown in FIG. As shown in FIG. 2A, the pixel 321 has a photodiode PD (corresponding to a photoelectric conversion element described in claims) formed on the surface layer portion of the silicon substrate 41, and in the vicinity thereof. A floating diffusion portion FD is formed. Further, on the surface of the silicon substrate 41 and above the channel region between the photodiode PD and the floating diffusion portion FD, a transfer transistor 43 (a gate element described in claims) is interposed via a gate insulating film 42. The gate electrode 44 is formed. The photodiode PD and the transfer transistor 43 are individually separated by an element isolation layer (LOCOS) 45 for each pixel. Further, on the surface of the silicon substrate 41, metal wirings 47, 48, and 49 are provided in three layers via an interlayer insulating layer 46, and the color filter 51 and the metal wirings 47 and 48 are provided thereon via a planarization film (passivation film) or the like. An on-chip lens 52 is disposed.

  The color filter 51 and the on-chip lens 52 of the pixel 321 located at the center of the effective pixel region 32 have an optical axis aligned with the axis of the imaging light beam 53a having an incident angle of 0 degrees that coincides with the axis passing through the center of the photodiode PD. Then it is arranged. Further, the metal wirings 47, 48, 49 extend in a direction in which a light receiving opening 54a for guiding the imaging light beam 53a collected by the on-chip lens 52 to the photodiode PD is orthogonal to the photodiode PD, And it is arranged in three layers along the row direction or the column direction of the pixels 321 from the photodiode PD toward the on-chip lens 52 so that the direction is maintained.

  A pixel 322 around the effective pixel region 32 includes a pixel having an element structure shown in FIG. Similar to the element structure of the pixel 321 in the effective pixel region 32, the pixel 322 includes a photodiode PD formed on the surface layer portion of the silicon substrate 41, and a floating diffusion portion FD is formed in the vicinity thereof. A gate electrode 44 of the transfer transistor 43 is formed above the channel region between the photodiode PD and the floating diffusion portion FD on the surface of the silicon substrate 41 via a gate insulating film 42. The photodiode PD and the transfer transistor 43 are individually separated by the element isolation layer 45 for each pixel. Further, on the surface of the silicon substrate 10, metal wirings 47, 48, 49 are provided in three layers via an interlayer insulating layer 46, and a color filter 51 and an on-chip lens 52 are provided thereon via a planarizing film or the like. Is arranged.

The color filter 51 and the on-chip lens 52 of the pixel 322 around the effective pixel region 32 correspond to the incident angle of the imaging light beam 53b inclined at a large incident angle toward the peripheral side of the effective pixel region 32. They are shifted in the direction approaching the center. In this case, as shown in FIG. 2B, the shift amount of the on-chip lens 52 is set larger than the shift amount of the color filter 51.
The metal wirings 47, 48, and 49 are arranged so as to maintain the light receiving opening 54b for guiding the imaging light beam 52a collected by the on-chip lens 52 to the photodiode PD. The pixels 47, 48, and 49 are shifted in the direction approaching the center of the effective pixel region 32 from the photodiode PD toward the on-chip lens 52 so that the light receiving opening 54b extends along the inclined imaging light beam 53b. 321 are arranged in three layers along the row direction or the column direction. In this case, the shift amount of the metal wirings 47, 48, 49 becomes larger as going to the upper layer.
2A and 2B show the central pixel 321 and the peripheral pixel 322 of the effective pixel region 32, but exist between the central pixel 321 and the peripheral pixel 322. The incident angle of the imaging light beam with respect to each pixel increases as it goes toward the central pixel 321 and the peripheral pixel 322, and the effective pixel region of the on-chip lens 52 and the metal wires 47, 48, and 49 corresponds to this incident angle. The amount of shift of 32 toward the center also changes.

  The pixel 331 in the invalid pixel region 33 includes a pixel having an element structure illustrated in FIG. Similar to the element structure of the pixel 321 in the effective pixel region 32, the pixel 331 includes a photodiode PD formed on the surface layer portion of the silicon substrate 41, and a floating diffusion portion FD is formed in the vicinity thereof. A gate electrode 44 of the transfer transistor 43 is formed above the channel region between the photodiode PD and the floating diffusion portion FD on the surface of the silicon substrate 41 via a gate insulating film 42. The photodiode PD and the transfer transistor 43 are individually separated by the element isolation layer 45 for each pixel. Further, on the surface of the silicon substrate 10, metal wirings 47, 48, 49 are provided in three layers via an interlayer insulating layer 46, and a color filter 51 and an on-chip lens 52 are provided thereon via a planarizing film or the like. Is arranged.

The on-chip lens 52 of the pixel 331 in the invalid pixel region 33 is disposed with its optical axis aligned on an axis that matches the axis passing through the center of the photodiode PD. In this case, since the signal of the pixel 331 is treated as an invalid pixel signal, it is not necessary for the imaging light beam 53c incident on the on-chip lens 52 to be efficiently focused on the photodiode PD, and therefore the incident angle of the imaging light beam 53c. The arrangement relationship between the on-chip lenses 52 is arbitrary.
Further, in the invalid pixel region 33 shown in this embodiment, the metal wirings 47, 48, and 49 leak into the pixels 351 of the effective OPB pixel region 35 where a part of the imaging light beam 53c irregularly reflected by these metal wirings is adjacent. There is no wiring pattern layout. That is, the metal wirings 47, 48, 49 extend in a direction in which the light receiving opening 54c for guiding the imaging light beam 53a collected by the on-chip lens 52 to the photodiode PD is orthogonal to the photodiode PD, In addition, the pixels 331 are arranged in three layers along the row direction or the column direction from the photodiode PD toward the on-chip lens 52 so that the direction is maintained.

  A pixel 351 in the effective OPB pixel region 35 includes a pixel having an element structure shown in FIG. Similar to the element structure of the pixel 321 in the effective pixel region 32, the pixel 351 includes a photodiode PD formed on the surface layer portion of the silicon substrate 41, and a floating diffusion portion FD is formed in the vicinity thereof. A gate electrode 44 of the transfer transistor 43 is formed above the channel region between the photodiode PD and the floating diffusion portion FD on the surface of the silicon substrate 41 via a gate insulating film 42. The photodiode PD and the transfer transistor 43 are individually separated by the element isolation layer 45 for each pixel. On the surface of the silicon substrate 10, metal wirings 47, 48, and 49 are provided in three layers via an interlayer insulating layer 46, and a color filter 51 is disposed thereon via a planarizing film or the like. .

In the pixel 351 of the effective OPB pixel region 35, the metal wirings 47, 48, and 49 have light receiving openings 54d formed corresponding to the photodiode PD extending in a direction orthogonal to the photodiode PD, and The pixels 351 are arranged in three layers in the row direction or the column direction from the photodiode PD toward the on-chip lens 52 so that the direction is maintained.
The uppermost metal wiring 49 also serves as a light shielding film that shields light imaged by an optical system such as a camera lens from entering the imaging surface 31 of the solid-state imaging device 30.

In the solid-state imaging device 30 configured as described above, when an image of the light of the subject is formed on the imaging surface 31 by an optical system such as a camera lens, the imaging light rays are shown in FIGS. 2 (A) and 2 (B). As described above, the light is collected by the on-chip lens 52 constituting the pixels of the effective pixel region 32 and is incident on the photodiode PD through the color filter 51. The signal charge generated by the photodiode PD is transferred to the floating diffusion part by the transfer transistor, the potential fluctuation of the floating diffusion part is detected by the amplification transistor, and this is converted into an electric signal. As a pixel signal, it is output to a signal processing unit (not shown) to perform predetermined image processing.
Further, the image light beam 53 c incident on the invalid pixel region 33 is collected by the on-chip lens 52 and is incident on the photodiode PD through the color filter 51 as shown in FIG. The signal charge generated by the photodiode PD is transferred to the floating diffusion part by the transfer transistor, and the potential fluctuation of the floating diffusion part is detected by the amplification transistor and converted into an electric signal. This electrical signal is processed as an invalid pixel signal that is not valid.

  On the other hand, the image light beam 53c incident on the invalid pixel region 33 is collected by the on-chip lens 52 and is incident on the photodiode PD through the color filter 51. The metal wirings 47, 48, and 49 of the pixel 331 receive light. Since the openings 54c extend in a direction orthogonal to the photodiode PD and are arranged in three layers from the photodiode PD toward the on-chip lens 52 so as to maintain the direction, the on-chip The amount of vignetting of incident light collected by the lens 52 by the metal wirings 47, 48, and 49 is reduced, and a part of the light 53c1 reflected by the metal wirings 47, 48, and 49 is shown in FIG. Thus, it is returned to the photodiode PD. Further, a part of the light 53c2 reflected toward the outside of the pixel 331 by the metal wirings 47, 48, and 49 is a pixel in the adjacent effective OPB pixel region 35 as shown in FIGS. The light that leaks into the effective OPB pixel region 35 can be suppressed without leaking into the 351.

  According to the first embodiment as described above, the invalid pixel region 33 adjacent to the effective OPB pixel region 35 is provided around the effective pixel region 32 in the solid-state imaging device 30, and a plurality of layers of wirings in the invalid pixel region 33 are provided. Since the light receiving openings 54c of the ineffective pixel region 33 extend in the direction orthogonal to the photodiode PD from the photodiode PD toward the on-chip lens 52, the effective OPB pixels Even if incident light is irregularly reflected by the wirings 47, 48, and 49 of the invalid pixel region 33 adjacent to the region 35, the irregularly reflected light can be prevented or suppressed from leaking into the OPB pixel of the effective OPB pixel region 35, Moreover, even if the light incident angle from the optical system such as the camera lens with respect to the imaging surface of the solid-state imaging device 30 changes, the effective OPB pixel region 3 Eliminates the noise increased OPB pixels signals by diffused reflection of light to, this, it is possible to obtain a high-quality image signal can be prevented a deviation of the black level.

In addition, the invalid OPB pixel area 34 in this embodiment is an invalid pixel signal whose signal is not valid, so that the invalid OPB pixel area 34 adjacent to the invalid OPB pixel area 34 has a metal wiring or the like. Even if the irregularly reflected light leaks, this does not adversely affect the image signal, such as image quality degradation.
In this embodiment, by providing the dummy pixel region 36, the signal of the pixel can be used as a dummy signal of the solid-state imaging device.
In this embodiment, the plurality of layers of wirings 47, 48, and 49 in the effective OPB pixel region 35 have their light receiving openings 54 d with respect to the photodiode PD from the photodiode PD toward the wiring stacking direction. Since it arrange | positions so that it may extend in the orthogonal direction, the penetration | invasion of the leak light from an adjacent pixel area | region can be suppressed.

(Embodiment 2)
Next, an example in which the solid-state imaging device described in Embodiment 1 is applied to an imaging device such as a video camera capable of shooting a moving image or a camera built in a mobile phone will be described with reference to FIG.
In FIG. 3, an imaging device 60 includes a solid-state imaging device 61, an optical system 62 that guides incident light from a subject to the solid-state imaging device 61, a signal processing circuit 63 that processes an output signal from the solid-state imaging device 61, The driving circuit 64 for driving the solid-state image sensor 61 is provided.
In the imaging device 60, the solid-state imaging device 30 according to the first embodiment is used as the solid-state imaging device 61.

  The drive circuit 64 supplies a drive signal that controls the transfer operation of the solid-state image sensor 61 and the shutter operation of a shutter device (not shown) built in the solid-state image sensor 61. Further, charge transfer of the solid-state imaging device 61 is performed by a drive signal (timing signal) supplied from the drive circuit 63. The signal processing circuit 63 performs various types of signal processing according to a video camera, a mobile phone, or the like. The video signal subjected to the signal processing is stored in a storage medium (not shown) such as a memory, or is output to a monitor (not shown) to display the video.

  According to such an imaging apparatus, by using the solid-state imaging device according to the first embodiment described above, even if incident light is irregularly reflected by the wiring in the invalid pixel region, the irregularly reflected light is optical black in the optical black pixel region. Leakage into the pixel can be prevented or suppressed, whereby black level deviation can be prevented and a high-quality image signal can be obtained, and a high-quality imaging device can be provided.

It is a schematic block diagram of the solid-state image sensor containing the effective pixel area | region and OPB pixel area | region in Embodiment 1 of this invention. 3 is an explanatory diagram illustrating an element structure of an image in each pixel region of the solid-state imaging element according to Embodiment 1. FIG. It is a block diagram which shows the whole structure of the imaging device using the solid-state image sensor shown in this Embodiment 1. FIG. It is a schematic block diagram of the solid-state image sensor containing the effective pixel area | region and OPB pixel area | region in the past. It is explanatory drawing which shows the relationship with the incident angle of the camera lens with respect to the imaging surface of a solid-state image sensor. It is explanatory drawing which shows the element structure of the image in each pixel area | region of the conventional solid-state image sensor.

Explanation of symbols

  30... Solid imaging device 31. Imaging surface 32. Effective pixel region 33. Invalid pixel region 34. Invalid OPB pixel region 35 35 Effective OPB pixel region 36. Dummy pixel region 321,331,351,322 ... pixel, PD ... photodiode, FP ... floating diffusion part, 41 ... silicon substrate, 43 ... transfer transistor, 44 ... gate electrode, 45 ... element isolation layer, 46: Interlayer insulating layer, 47, 48, 49 ... Metal wiring, 50 ... Planarization film, 51 ... Color filter, 52 ... On-chip lens, 60 ... Imaging device, 61 ... Solid-state imaging device, 62: Optical system, 63: Signal processing circuit, 64: Drive circuit.

Claims (10)

An effective pixel region in which a plurality of pixels including a photoelectric conversion element and a gate element are arranged in a two-dimensional array on a semiconductor substrate, and a signal of the pixel is used as an effective pixel signal;
A plurality of pixels arranged on the outer periphery of the effective pixel region and including a photoelectric conversion element and a gate element on the semiconductor substrate, and an invalid pixel region in which the signal of the pixel is an invalid pixel signal;
An optical black pixel region that is arranged on the outer periphery of the invalid pixel region and is arranged in a state where a plurality of pixels including a photoelectric conversion element and a gate element are shielded from light on the semiconductor substrate, and a signal of the pixel is used as a black level reference; ,
Provided in a plurality of layers through an insulating layer in the pixel array direction so as to secure a light receiving opening for guiding the imaging light beam for each photoelectric conversion element of each pixel on the semiconductor substrate in the pixel region. Wiring and
A first on-chip lens that is arranged for each pixel above the wiring including the insulating layer in the effective pixel region and collects the imaging light beam to the photoelectric conversion element through the light receiving opening;
A second on-chip lens that is arranged for each pixel above the wiring including the insulating layer in the invalid pixel region and collects the imaging light beam to the photoelectric conversion element through the light receiving opening,
The first on-chip lens is effective for each pixel in the effective pixel region corresponding to an incident angle of the imaging light beam to the effective pixel region that increases as it goes from the center to the periphery of the effective pixel region. Arranged in a direction approaching the center of the pixel area,
The plurality of layers of wirings in the effective pixel region are arranged so that the imaging light beam is in a direction approaching the center of the effective pixel region from the photoelectric conversion element toward the first on-chip lens while maintaining the light receiving opening. It is arranged by shifting according to the incident angle,
The plurality of layers of wiring in the invalid pixel region extend in a direction in which the light receiving opening in the invalid pixel region is orthogonal to the photoelectric conversion element from the photoelectric conversion element toward the second on-chip lens. Located in the
A solid-state imaging device.   The plurality of layers of wiring in the optical black pixel region extend in a direction in which the light receiving opening of the optical black pixel region is orthogonal to the photoelectric conversion element from the photoelectric conversion element toward the stacking direction of the wiring. The solid-state imaging device according to claim 1, wherein the solid-state imaging device is arranged as described above.   2. The solid-state image pickup device according to claim 1, wherein the uppermost layer wiring in the optical black pixel region also serves as a light shielding layer.   A plurality of pixels are arranged between the effective pixel region and the invalid pixel region, and an invalid optical black pixel region in which a signal of the pixel is an invalid pixel signal is provided. The solid-state imaging device according to claim 1.   2. The solid-state image pickup device according to claim 1, wherein a dummy pixel region in which a plurality of pixels are arranged and a signal of the pixel is a dummy is provided on an outer periphery of the optical black pixel region. A solid-state image sensor;
An optical system for guiding incident light from a subject to the solid-state imaging device;
A signal processing circuit for processing an output signal from the solid-state imaging device,
The solid-state imaging device is
An effective pixel region in which a plurality of pixels including a photoelectric conversion element and a gate element are arranged in a two-dimensional array on a semiconductor substrate, and a signal of the pixel is used as an effective pixel signal;
A plurality of pixels arranged on the outer periphery of the effective pixel region and including a photoelectric conversion element and a gate element on the semiconductor substrate, and an invalid pixel region in which the signal of the pixel is an invalid pixel signal;
An optical black pixel region that is arranged on the outer periphery of the invalid pixel region and is arranged in a state where a plurality of pixels including a photoelectric conversion element and a gate element are shielded from light on the semiconductor substrate, and a signal of the pixel is used as a black level reference; ,
Provided in a plurality of layers through an insulating layer in the pixel array direction so as to secure a light receiving opening for guiding the imaging light beam for each photoelectric conversion element of each pixel on the semiconductor substrate in the pixel region. Wiring and
A first on-chip lens that is arranged for each pixel above the wiring including the insulating layer in the effective pixel region and collects the imaging light beam to the photoelectric conversion element through the light receiving opening;
A second on-chip lens that is arranged for each pixel above the wiring including the insulating layer in the invalid pixel region and collects the imaging light beam to the photoelectric conversion element through the light receiving opening,
The first on-chip lens is effective for each pixel in the effective pixel region corresponding to an incident angle of the imaging light beam to the effective pixel region that increases as it goes from the center to the periphery of the effective pixel region. Arranged in a direction approaching the center of the pixel area,
The plurality of layers of wirings in the effective pixel region are arranged so that the imaging light beam is in a direction approaching the center of the effective pixel region from the photoelectric conversion element toward the first on-chip lens while maintaining the light receiving opening. It is arranged by shifting according to the incident angle,
The plurality of layers of wiring in the invalid pixel region extend in a direction in which the light receiving opening in the invalid pixel region is orthogonal to the photoelectric conversion element from the photoelectric conversion element toward the second on-chip lens. Located in the
An imaging apparatus characterized by that.   The plurality of layers of wiring in the optical black pixel region extend in a direction in which the light receiving opening of the optical black pixel region is orthogonal to the photoelectric conversion element from the photoelectric conversion element toward the stacking direction of the wiring. The imaging apparatus according to claim 6, wherein the imaging apparatus is arranged so as to perform.   The imaging apparatus according to claim 6, wherein the uppermost layer wiring in the optical black pixel region also serves as a light shielding layer.   A plurality of pixels are arranged between the effective pixel region and the invalid pixel region, and an invalid optical black pixel region in which a signal of the pixel is an invalid pixel signal is provided. The imaging device according to claim 6.   The imaging apparatus according to claim 6, wherein a dummy pixel region in which a plurality of pixels are arranged and a signal of the pixel is a dummy is provided on an outer periphery of the optical black pixel region.

Images