IMAGING APPARATUS AND ELECTRONIC DEVICE

An imaging apparatus including: a first imaging element and a second imaging element, in which each of the first and second imaging elements includes: a plurality of pixels in a semiconductor substrate; a pixel separation wall; and a color filter above a light receiving surface of the semiconductor substrate that transmits light having a wavelength that is different between the first imaging element and the second imaging element, the pixel separation wall included in the first imaging element has a slit at a center of the first imaging element where the imaging apparatus is viewed from a side of the light receiving surface, and the pixel separation wall included in the second imaging element does not have a slit at a center of the second imaging element where the imaging apparatus is viewed from a side of the light receiving surface.

TECHNICAL FIELD

The present disclosure relates to an imaging apparatus and an electronic device.

BACKGROUND ART

These days, in an imaging apparatus, a technique in which a phase difference is detected by using a pair of adjacent phase difference detection pixels is employed as an autofocus function. Examples of such a technique include imaging elements disclosed in Patent Documents 1 to 3 below.

CITATION LIST

Patent Document

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

However, in the technologies disclosed in Patent Documents 1 and 2 above, it is difficult to completely prevent the inflow of charge to an adjacent phase difference detection pixel, and hence there is a limit to further improving the accuracy of phase difference detection. Further, in the technology disclosed in Patent Document 3 above, although the inflow of charge like that described above can be avoided, in a case where light of a long wavelength is incident on the imaging element, the light is likely to be irregularly reflected by a separation wall that separates pixels, and hence crosstalk between adjacent pixels is likely to occur and degradation of a captured image may be caused.

Thus, the present disclosure proposes an imaging apparatus and an electronic device capable of avoiding degradation of a captured image while improving the accuracy of phase difference detection.

Solutions to Problems

According to the present disclosure, there is provided an imaging apparatus including: a first imaging element and a second imaging element each of which converts light to a charge, in which each of the first and second imaging elements includes: a plurality of pixels that is provided in a semiconductor substrate and is adjacent to each other; a pixel separation wall that separates adjacent ones of the plurality of pixels; and a color filter that is provided above a light receiving surface of the semiconductor substrate and transmits light having a wavelength that is different between the first imaging element and the second imaging element, the pixel separation wall included in the first imaging element has a slit at a center of the first imaging element in a case where the imaging apparatus is viewed from a side of the light receiving surface, and the pixel separation wall included in the second imaging element does not have a slit at a center of the second imaging element in a case where the imaging apparatus is viewed from a side of the light receiving surface.

Furthermore, according to the present disclosure, there is provided an electronic device including: an imaging apparatus including a first imaging element and a second imaging element each of which converts light to a charge, in which each of the first and second imaging elements includes: a plurality of pixels that is provided in a semiconductor substrate and is adjacent to each other; a pixel separation wall that separates adjacent ones of the plurality of pixels; and a color filter that is provided above a light receiving surface of the semiconductor substrate and transmits light having a wavelength that is different between the first imaging element and the second imaging element, the pixel separation wall included in the first imaging element has a slit at a center of the first imaging element in a case where the imaging apparatus is viewed from a side of the light receiving surface, and the pixel separation wall included in the second imaging element does not have a slit at a center of the second imaging element in a case where the imaging apparatus is viewed from a side of the light receiving surface.

MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present disclosure will be described below in detail with reference to the drawings. In each of the following embodiments, the same parts are denoted by the same reference symbols, and a repetitive description thereof will be omitted.

Note that, in the present specification and the drawings, a plurality of structural elements that has substantially the same or similar function and structure is sometimes distinguished from each other using different numbers after the same reference sign. However, in a case where there is no need in particular to distinguish the plurality of structural elements that has substantially the same or similar function and structure, the same reference sign alone is attached. Further, there are cases in which similar structural elements of different embodiments are distinguished by adding the same reference numeral followed by different letters. However, in a case where it is not necessary to particularly distinguish each of similar structural element, only the same reference signs are attached.

Further, the drawings referred to in the following description are drawings for promoting the description and understanding of an embodiment of the present disclosure, and the shapes, dimensions, ratios, etc. shown in the drawings may be different from the actual ones for the sake of clarity. Further, the imaging apparatus shown in the drawings may be modified in design with consideration of the following description and known technology, as appropriate. Further, in the description using a cross-sectional view of the imaging apparatus, the up-down direction of the stacked structure of the imaging apparatus corresponds to a relative direction in a case where a light receiving surface that light incident on the imaging apparatus enters is assumed to be the upside, and may be different from the up-down direction according to the actual gravitational acceleration.

The dimensions expressed in the following description mean not only mathematically or geometrically defined dimensions but also dimensions including a difference (error or distortion) to an allowable extent in the operation of the imaging apparatus and the manufacturing process of the imaging apparatus. Further, “substantially the same” used for specific dimensions in the following description means not only a case of being mathematically or geometrically completely matched but also a case of having a difference (error or distortion) to an allowable extent in the operation of the imaging apparatus and the manufacturing process of the imaging apparatus.

Further, in the following description, “electrically connect” means that a plurality of elements is directly connected or is indirectly connected via another element.

Further, in the following description, “sharing” means that mutually different elements (for example, pixels or the like) use another element (for example, an on-chip lens or the like) together.

Note that the description is given in the following order.

1. Schematic Configuration of Imaging Apparatus

2. Schematic Configuration of Imaging Element According to Comparative Example

3. Background in Which Present Inventor has Created Embodiment According to Present Disclosure

4. First Embodiment

4.3 Modification Examples

5. Second Embodiment

6.3 Modification Examples

8.3 Modification Example

13. Application Example to Camera

14. Application Example to Smartphone

15. Application Example to Endoscopic Surgery System

16. Application Example to Mobile Body

<<1. Schematic Configuration of Imaging Apparatus>>

First, a schematic configuration of an imaging apparatus1according to an embodiment of the present disclosure is described with reference toFIG.1.FIG.1is an explanatory diagram showing a planar configuration example of an imaging apparatus1according to an embodiment of the present disclosure. As shown inFIG.1, the imaging apparatus1according to an embodiment of the present disclosure includes, on a semiconductor substrate10containing, for example, silicon, a pixel array section (light receiving section)30in which a plurality of imaging elements100is arranged in a matrix form and a peripheral circuit unit provided to surround the pixel array section30. Further, the imaging apparatus1includes, as the peripheral circuit unit, a vertical drive circuit unit32, a column signal processing circuit unit34, a horizontal drive circuit unit36, an output circuit unit38, a control circuit unit40, etc. Hereinbelow, details of each block of the imaging apparatus1are described.

The pixel array section30includes, on the semiconductor substrate10, a plurality of imaging elements100two-dimensionally arranged in a matrix form along the row direction and the column direction. Each imaging element100includes a photoelectric conversion section (illustration omitted) and a plurality of pixel transistors (for example, metal-oxide-semiconductor (MOS) transistors) (illustration omitted). Specifically, the pixel transistors include, for example, four MOS transistors of a transfer transistor, a selection transistor, a reset transistor, and an amplification transistor. Note that in the pixel array section30, a plurality of imaging elements100is two-dimensionally arranged in a Bayer array, for example. Here, the Bayer array is an array pattern in which imaging elements100each of which absorbs light having a green wavelength (for example, a wavelength of 495 nm to 570 nm) and generates a charge are arranged in a checkered pattern, and in the remaining portion, imaging elements100each of which absorbs light having a red wavelength (for example, a wavelength of 620 nm to 750 nm) and generates a charge and imaging elements100each of which absorbs light having a blue wavelength (for example, a wavelength of 450 nm to 495 nm) and generates a charge are alternately arranged on a line basis. Further, a detailed structure of the imaging element100is described later.

The vertical drive circuit unit32includes, for example, a shift register; and selects a pixel drive wiring42, supplies a pulse for driving the imaging element100to the selected pixel drive wiring42, and drives the imaging element100in units of rows. That is, the vertical drive circuit unit32selectively scans each imaging element100of the pixel array section30in a sequential manner in the vertical direction (the up-down direction inFIG.1) in units of rows, and supplies a pixel signal based on a signal charge generated in accordance with the amount of light received by a photoelectric conversion section (illustration omitted) of each imaging element100to the column signal processing circuit unit34described later through a vertical signal line44.

The column signal processing circuit unit34is provided for each column of imaging elements100, and performs signal processing such as noise removal on pixel signals outputted from imaging elements100of one row, on a pixel column basis. For example, the column signal processing circuit unit34performs signal processing such as correlated double sampling (CDS) and analog-degital (AD) conversion in order to remove pixel-specific fixed pattern noise.

The horizontal drive circuit unit36includes, for example, a shift register; and sequentially outputs horizontal scanning pulses, thus successively selects the sections of the column signal processing circuit unit34described above, and causes each section of the column signal processing circuit unit34to output a pixel signal to a horizontal signal line46.

The output circuit unit38performs signal processing on pixel signals sequentially supplied from the sections of the column signal processing circuit unit34described above through the horizontal signal line46, and outputs the results. The output circuit unit38may function as, for example, a functional section that performs buffering, or may perform processing such as black level adjustment, column variation correction, or various pieces of digital signal processing. Note that the buffering refers to temporarily storing pixel signals at the time of pixel signal exchange in order to compensate differences in processing speed and transfer speed. Further, an input and output terminal48is a terminal for exchanging signals with an external apparatus.

The control circuit unit40receives an input clock and data that gives commands of an operating mode, etc., and outputs data such as inside information of the imaging apparatus1. That is, the control circuit unit40generates clock signals and control signals serving as standards of the operations of the vertical drive circuit unit32, the column signal processing circuit unit34, the horizontal drive circuit unit36, etc. on the basis of a vertical synchronizing signal, a horizontal synchronizing signal, and a master clock. Then, the control circuit unit40outputs the generated clock signals and control signals to the vertical drive circuit unit32, the column signal processing circuit unit34, the horizontal drive circuit unit36, etc.

<<2. Schematic Configuration of Imaging Element According to Comparative Example>>

Meanwhile, in order to further improve the autofocus function while avoiding degradation of a captured image, that is, in order to improve the accuracy of phase difference detection, the present inventor was making extensive studies on providing phase difference detection pixels on the entire surface of the pixel array section30of the imaging apparatus1(all-pixel phase difference detection). Under such circumstances, it has been studied to provide, on the entire surface of the pixel array section30, imaging elements100aeach of which functions as one imaging element at the time of imaging and functions as two phase difference detection pixels at the time of phase difference detection (a dual photodiode structure).

Thus, before describing details of the imaging element100according to an embodiment of the present disclosure, a schematic configuration of an imaging element100aaccording to a comparative example that the present inventor studied first is described with reference toFIG.2.FIG.2is an explanatory diagram showing part of a cross section of an imaging element100aaccording to a comparative example, and specifically corresponds to a cross section of the imaging element100ataken along the thickness direction of the semiconductor substrate10. Note that, here, as described above, the comparative example means an imaging element that the present inventor extensively studied before making the embodiment of the present disclosure.

A plurality of imaging elements100aaccording to the comparative example is provided on the semiconductor substrate10to be adjacent to each other. Then, as shown inFIG.2, the imaging element100aincludes an on-chip lens200, a color filter202, a light blocking section204, a semiconductor substrate10, and transfer gates400aand400b. Further, the imaging element100aincludes pixels300aand300bprovided in the semiconductor substrate10and each having a photoelectric conversion section302, a pixel separation wall304that separates these pixels300aand300b, and an element separation wall310that surrounds the two pixels300aand300b. Hereinbelow, a stacked structure of the imaging element100aaccording to the comparative example is described; the following description is given in order from the upper side (the light receiving surface l0aside) to the lower side inFIG.2.

As shown inFIG.2, the imaging element100aincludes one on-chip lens200that is provided above the light receiving surface l0aof the semiconductor substrate10and condenses incident light on the photoelectric conversion section302described later.

Then, incident light condensed by the on-chip lens200is incident on the photoelectric conversion sections302of the two pixels300aand300bvia the color filter202provided below the on-chip lens200. The color filter202is any of a color filter that transmits a red wavelength component, a color filter that transmits a green wavelength component, and a color filter that transmits a blue wavelength component.

Further, the light blocking section204is provided on the light receiving surface l0aof the semiconductor substrate10so as to surround the color filter202. The light blocking section204is provided between adjacent imaging elements100ato perform light blocking between the adjacent imaging elements100a.

Further, for example, in a semiconductor substrate10of a second conductivity type (for example, a P-type), two photoelectric conversion sections302each containing an impurity of a first conductivity type (for example, an N-type) are provided individually for pixels300aand300b. The photoelectric conversion section302absorbs light having a red wavelength component, a green wavelength component, or a blue wavelength component incident via the color filter202, and generates a charge.

In the imaging element100a, the photoelectric conversion section302of pixel300aand the photoelectric conversion section302of pixel300bfunction as two phase difference detection pixels at the time of phase difference detection.

Specifically, in the photoelectric conversion section302, the amount of charge generated, that is, the sensitivity varies depending on the angle of incidence of light with respect to the optical axis of the photoelectric conversion section302itself (an axis perpendicular to the light receiving surface). For example, the photoelectric conversion section302has the highest sensitivity in a case where the angle of incidence is 0 degrees, and further the sensitivity of the photoelectric conversion section302has, with the angle of incidence, a line-symmetric relationship of which the object axis is 0 degrees in terms of the angle of incidence. Therefore, light from the same point is incident on the photoelectric conversion section302of pixel300aand the photoelectric conversion section302of pixel300bat different angles of incidence, and these photoelectric conversion sections302generate amounts of charge according to the angles of incidence; hence, a shift (phase difference) occurs between the detected images. That is, the phase difference can be detected by detecting a difference between pixel signals based on the amounts of charge generated in the photoelectric conversion section302of pixel300aand the photoelectric conversion section302of pixel300b. Thus, autofocus can be achieved by a process in which such a difference (phase difference) between pixel signals is, for example, detected as a differential signal in a detection section (illustration omitted) of the output circuit unit38, the amount of defocus is calculated on the basis of the detected phase difference, and an imaging lens (illustration omitted) is adjusted (moved).

Further, in the comparative example, pixels300aand300beach having the photoelectric conversion section302are physically separated by the pixel separation wall304. The pixel separation wall304includes rear deep trench isolation (RDTI). The RDTI is formed by forming a trench penetrating from the light receiving surface10a(back surface) side of the semiconductor substrate10to an intermediate place of the semiconductor substrate10along the thickness direction of the semiconductor substrate10and filling the trench with a material including an oxide film or a metal film. Note that in the imaging element100a, the accuracy of phase difference detection is degraded in a case where at the time of phase difference detection, pixel signals outputted by the two pixels300aand300b(specifically, the photoelectric conversion sections302) are mixed with each other and color mixing occurs. Thus, in the imaging element100a, in order to further improve the accuracy of phase difference detection, the pixel separation wall304is required to separate the two pixels300aand300bto prevent color mixing.

Further, as described above, in the imaging element100a, the photoelectric conversion section302of pixel300aand the photoelectric conversion section302of pixel300bfunction as the photoelectric conversion section302of one imaging element100aat the time of normal imaging.

Further, in the semiconductor substrate10, the element separation wall310that surrounds the two pixels300aand300bincluded in the imaging element100aand physically separates adjacent imaging elements100ais provided. The element separation wall310includes, for example, RDTI.

Further, charges generated in the photoelectric conversion section302of pixel300aand the photoelectric conversion section302of pixel300bare transferred via the transfer gates400aand400bprovided on the front surface10blocated on the opposite side to the light receiving surface10aof the semiconductor substrate10. Then, the charges may be accumulated in, for example, a floating diffusion section (charge accumulation section) (illustration omitted) provided in a semiconductor region having a first conductivity type (for example, an N-type) provided in the semiconductor substrate10.

Further, a plurality of pixel transistors (illustration omitted) for transferring a charge and reading out a charge as a pixel signal may be provided on the front surface10bof the semiconductor substrate10.

<<3. Background in Which Present Inventor has Created Embodiment According to Present Disclosure>>

Next, before describing details of an embodiment according to the present disclosure, the background in which the present inventor has created the embodiment according to the present disclosure is described with reference toFIG.3.FIG.3is an explanatory diagram showing a planar configuration of imaging elements100aaccording to the comparative example, and specifically corresponds to a cross section of the imaging element100ataken along line A-A′ shown inFIG.2.

As described above, in all-pixel phase difference detection, which the present inventor was making studies on, the suppression of mixing of outputs of the two pixels300aand300bat the time of phase difference detection is required in order to improve the accuracy of phase difference detection.

Thus, in Patent Document 1 above, as shown inFIG.3, two protrusions304that protrude from the element separation wall310toward the center of the imaging element100along the column direction and face each other are provided between the two pixels300aand300bincluded in each imaging element100a. In Patent Document 1 above, by providing such protrusions304, a charge generated in the photoelectric conversion section302of one of the two pixels300aand300bcan be prevented from flowing into the other pixel at the time of phase difference detection, and therefore mixing of outputs can be avoided. As a result, in Patent Document 1 above, the accuracy of phase difference detection is improved, and the occurrence of point defects on a captured image due to variations in charge inflow can be suppressed.

Further, in Patent Document 2 above, two separation sections serving as potential barriers that have mutually different potentials for a charge generated in the photoelectric conversion section are provided between two pixels included in each imaging element. In Patent Document 2 above, by providing such separation sections, mixing of outputs of the two pixels can be avoided at the time of phase difference detection, and thus the accuracy of phase difference detection is improved.

Further, in Patent Document 3 above, an insulating layer (illustration omitted) embedded in a substrate is provided between two pixels included in each imaging element. In Patent Document 3 above, by providing such an insulating layer, mixing of outputs of the two pixels can be avoided at the time of phase difference detection, and thus the accuracy of phase difference detection is improved.

However, a study by the present inventor shows that in the technologies disclosed in Patent Documents 1 and 2 above, it is difficult to completely prevent the inflow of charge to an adjacent pixel and hence there is a limit to improving the accuracy of phase difference detection. Further, in the technology disclosed in Patent Document 3 above, although such inflow of charge can be avoided, in a case where light of a long wavelength is incident on the imaging element, the light is likely to be irregularly reflected by the insulating layer provided between the two pixels. As a result, in Patent Document 3 above, crosstalk between adjacent imaging elements is likely to occur, and degradation of a captured image is caused.

Thus, in view of such circumstances, the present inventor, with attention on the characteristics of light incident on the imaging element100, has created an embodiment according to the present disclosure capable of avoiding degradation of a captured image while improving the accuracy of phase difference detection.

Specifically, focusing attention on the characteristics of light for different wavelength regions, green light has a short wavelength, and hence in a case where such light is incident on the imaging element, the light is absorbed by the photoelectric conversion section in the vicinity of the surface of the semiconductor substrate. Therefore, it is presumed that even if a pixel separation wall is provided between the two pixels, the light is less likely to be irregularly reflected by the pixel separation wall and crosstalk is less likely to occur. On the other hand, red light has a long wavelength, and hence in a case where such light is incident on the imaging element, the light is less likely to be absorbed by the photoelectric conversion section in the vicinity of the surface of the semiconductor substrate. Therefore, it is presumed that if a pixel separation wall is provided between the two pixels, the light is irregularly reflected by the pixel separation wall and is incident on an adjacent imaging element, and crosstalk is likely to occur. Thus, the present inventor, with attention on such characteristics of light, has created an embodiment according to the present disclosure.

Specifically, in an embodiment of the present disclosure created by the present inventor, in an imaging element (first imaging element)100that absorbs light having a red wavelength component and generates a charge, in a case where the imaging element100is viewed from the light receiving surface10aside, a slit312is provided in a portion in the vicinity of the center of the imaging element100of the pixel separation wall304that separates the two pixels300aand300b(seeFIG.4). By thus providing the slit312in the vicinity of the center of the imaging element100, an event where light incident on the vicinity of the center of the imaging element100is irregularly reflected by the pixel separation wall304and is incident on an adjacent imaging element100can be suppressed. As a result, in the embodiment of the present disclosure, crosstalk can be avoided, and eventually degradation of a captured image can be suppressed.

In addition, in the embodiment of the present disclosure created by the present inventor, it is presumed that in an imaging element (second imaging element)100that absorbs light having a green wavelength component and generates a charge, irregular reflection like that described above is less likely to occur; hence, in a case where the imaging element100is viewed from the light receiving surface l0aside, the slit312is not provided in the pixel separation wall304that separates the two pixels300aand300b(seeFIG.4). By means of the pixel separation wall304not provided with the slit312, an event where a charge generated in the photoelectric conversion section302of one of the two pixels300aand300bflows into the other pixel can be suppressed, and hence the separation ratio of pixels300aand300bcan be improved. Therefore, in the embodiment of the present disclosure, the accuracy of phase difference detection is improved, and the occurrence of point defects on a captured image due to variations in charge inflow can be suppressed.

That is, in the embodiment of the present disclosure created by the present inventor, degradation of a captured image can be avoided while the accuracy of phase difference detection is improved. Hereinbelow, details of embodiments according to the present disclosure are described in order.

First, a planar configuration of imaging elements100according to a first embodiment of the present disclosure is described with reference toFIG.4.FIG.4is an explanatory diagram showing a configuration example of imaging elements100according to the present embodiment; specifically, the diagram shown in the upper part ofFIG.4corresponds to a cross section of the imaging element100taken along line A-A′ shown inFIG.2, and the diagram shown in the lower part ofFIG.4corresponds to a cross section of the imaging element100taken along line B-B′ shown in the upper part ofFIG.4.

As shown in the upper part ofFIG.4, in the present embodiment, mutually adjacent two rectangular pixels300aand300bincluded in one imaging element100are separated by a pixel separation wall304formed integrally with the element separation wall310. Further, in the present embodiment, in each of the imaging elements (first imaging element and third imaging element)100that absorb light having a red wavelength component and light having a blue wavelength component and generate charges, the slit312is provided in a portion in the vicinity of the center of the imaging element100of the pixel separation wall304in a case where the imaging element100is viewed from the light receiving surface10aside. In other words, the element separation wall310of each of the imaging elements100that absorb red light and blue light has two protrusions304that protrude along the column direction toward the center of the imaging element100and face each other in a case where the imaging element100is viewed from above the light receiving surface10a. Note that in the present embodiment, the length of the slit312along the vertical direction inFIG.4is not particularly limited. Further, in the present embodiment, the position of the slit312is not limited to the center of the imaging element100, and may be shifted by a predetermined distance from the center of the imaging element100, for example.

In the present embodiment, in each of the imaging elements (first imaging element and third imaging element)100that absorb red light and blue light and generate charges, by providing the slit312in the vicinity of the center of the imaging element100, an event where light incident on the vicinity of the center of the imaging element100is irregularly reflected by the pixel separation wall304and is incident on an adjacent imaging element100can be suppressed. As a result, in the present embodiment, crosstalk can be avoided, and eventually degradation of a captured image can be suppressed.

On the other hand, in the present embodiment, in the imaging element (second imaging element)100that absorbs light having a green wavelength component and generates a charge, the slit312is not provided in the pixel separation wall304in a case where the imaging element100is viewed from the light receiving surface10aside.

In the present embodiment, in the imaging element (second imaging element)100that absorbs light having a green wavelength component and generates a charge, by means of the pixel separation wall304not provided with the slit312, an event where a charge generated in the photoelectric conversion section302of one of the two pixels300aand300bflows into the other pixel can be suppressed, and hence the separation ratio of pixels300aand300bcan be improved. As a result, in the present embodiment, in the imaging element100that absorbs light having a green wavelength component, the accuracy of phase difference detection is improved, and the occurrence of point defects on a captured image due to variations in charge inflow can be suppressed. In particular, since mainly the imaging element100that absorbs green light is used at the time of phase difference detection, the improvement of the accuracy of phase difference detection in the imaging element100is favorable.

That is, in the present embodiment, by a configuration in which pixel separation walls304having forms according to the difference in characteristics of light due to the difference in wavelength are provided individually for imaging elements100, degradation of a captured image can be avoided while the accuracy of phase difference detection is improved.

Further, in the present embodiment, like in the comparative example, the element separation wall310that surrounds the two pixels300aand300bincluded in each imaging element100and physically separates adjacent imaging elements100is provided. Note that although in the upper part ofFIG.4the widths of the element separation wall310and the pixel separation wall304are substantially the same, in the present invention the widths are not limited thereto.

Next, a cross-sectional configuration of imaging elements100according to the first embodiment of the present disclosure is described with reference to the diagram shown in the lower part ofFIG.4. As shown in the lower part ofFIG.4, the imaging element100according to the present embodiment includes, like in the comparative example, an on-chip lens200, a color filter202, a light blocking section (light blocking film)204, a semiconductor substrate10, and transfer gates400aand400b. Further, in the present embodiment, the imaging element100includes pixels300aand300bprovided in the semiconductor substrate10and each having a photoelectric conversion section302, a pixel separation wall304that separates these pixels300aand300b, and an element separation wall310that surrounds the two pixels300aand300bincluded in the imaging element100. Hereinbelow, a stacked structure of the imaging element100according to the present embodiment is described; the following description is given in order from the upper side (the light receiving surface l0aside) to the lower side in the diagram shown in the lower part ofFIG.4.

As shown in the lower part ofFIG.4, the imaging element100includes one on-chip lens200that is provided above the light receiving surface l0aof the semiconductor substrate10and condenses incident light on the photoelectric conversion section302. Like in the comparative example, the imaging element100has a structure in which two pixels300aand300bare provided for one on-chip lens200. That is, the on-chip lens200is shared by the two pixels300aand300b. Note that the on-chip lens200may include, for example, a silicon nitride film (SiN) or a resin-based material such as a styrene-based resin, an acrylic-based resin, a styrene-acrylic copolymer-based resin, or a siloxane-based resin.

Then, incident light condensed by the on-chip lens200is incident on the photoelectric conversion sections302of the two pixels300aand300bvia the color filter202provided below the on-chip lens200and above the light receiving surface10a. In other words, in the imaging element100, like in the comparative example, two pixels300aand300bare provided for a stack of one on-chip lens200and one color filter202. The color filter202is any of a color filter that transmits a red wavelength component, a color filter that transmits a green wavelength component, and a color filter that transmits a blue wavelength component. For example, the color filter202may contain, for example, a material in which a pigment or a dye is dispersed in a transparent binder such as silicone.

Further, the light blocking section204is provided on the light receiving surface10aof the semiconductor substrate10so as to surround the color filter202. By being provided between adjacent imaging elements100, the light blocking section204suppresses crosstalk between the adjacent imaging elements100, and performs light blocking between the adjacent imaging elements100in order to further improve accuracy at the time of phase difference detection. The light blocking section204may contain, for example, a metal material or the like containing tungsten (W), aluminum (Al), copper (Cu), titanium (Ti), molybdenum (Mo), nickel (Ni), or the like.

Further, for example, in a semiconductor substrate10of a second conductivity type (for example, a P-type), two photoelectric conversion sections302each containing an impurity of a first conductivity type (for example, an N-type) are provided individually for pixels300aand300b. As described above, the photoelectric conversion section302absorbs light having a red wavelength component, a green wavelength component, or a blue wavelength component incident via the color filter202, and generates a charge. Then, in the present embodiment, like in the comparative example, the photoelectric conversion section302of pixel300aand the photoelectric conversion section302of pixel300bfunction as a pair of phase difference detection pixels at the time of phase difference detection. That is, in the present embodiment, the phase difference can be detected by detecting the difference between pixel signals based on the amounts of charge generated in the photoelectric conversion section302of pixel300aand the photoelectric conversion section302of pixel300b. Note that although the above description is given on the assumption that the phase difference is detected as a difference between pixel signals of the photoelectric conversion section302of pixel300aand the photoelectric conversion section302of pixel300b, the present invention is not limited thereto; for example, the phase difference may be detected as a ratio between pixel signals of the photoelectric conversion section302of pixel300aand the photoelectric conversion section302of pixel300b.

Further, in the present embodiment, like in the comparative example, the two rectangular pixels300aand300bare separated from each other by the pixel separation wall304that is RDTI provided to penetrate from the light receiving surface10ato an intermediate place of the semiconductor substrate10along the thickness direction of the semiconductor substrate10. As described above, the RDTI is formed by forming a trench (illustration omitted) penetrating from the light receiving surface10a(back surface) side of the semiconductor substrate10to an intermediate place of the semiconductor substrate10along the thickness direction of the semiconductor substrate10and filling the trench with a material including an oxide film or a metal film such as a silicon oxide film (SiO), a silicon nitride film, amorphous silicon, polycrystalline silicon, a titanium oxide film (TiO), aluminum, or tungsten.

Further, in the present embodiment, like in the comparative example, the element separation wall310that surrounds the two pixels300aand300bincluded in the imaging element100and physically separates adjacent imaging elements100is provided in the semiconductor substrate10. The element separation wall310is RDTI provided to penetrate from the light receiving surface10ato an intermediate place of the semiconductor substrate10. That is, the element separation wall310includes a trench (illustration omitted) that penetrates from the light receiving surface l0a(back surface) side of the semiconductor substrate10to an intermediate place of the semiconductor substrate10along the thickness direction of the semiconductor substrate10and a material including an oxide film or a metal film such as a silicon oxide film, a silicon nitride film, amorphous silicon, polycrystalline silicon, a titanium oxide film, aluminum, or tungsten embedded in the trench.

Note that although as shown in the lower part ofFIG.4the depths of the pixel separation wall304and the element separation wall310from the light receiving surface10aof the semiconductor substrate10are substantially the same, the present embodiment is not limited thereto.

Further, also in the present embodiment, charges generated in the photoelectric conversion section302of pixel300aand the photoelectric conversion section302of pixel300bare transferred via transfer gates400aand400bof transfer transistors (a kind of the pixel transistors described above) provided on the front surface10blocated on the opposite side to the light receiving surface10aof the semiconductor substrate10. Each of the transfer gates400aand400bmay include, for example, a metal film. Then, the charges may be accumulated in, for example, a floating diffusion section (charge accumulation section) (illustration omitted) provided in a semiconductor region having a first conductivity type (for example, an N-type) provided in the semiconductor substrate10. Note that in the present embodiment, the floating diffusion section is not limited to being provided in the semiconductor substrate10, and may be provided in another substrate (illustration omitted) stacked on the semiconductor substrate10, for example.

Further, a plurality of pixel transistors (illustration omitted) that is different from the transfer transistor described above and is used for readout of a charge as a pixel signal or for other purposes may be provided on the front surface10bof the semiconductor substrate10. Further, in the present embodiment, the pixel transistor may be provided in the semiconductor substrate10, or may be provided in another substrate (illustration omitted) stacked on the semiconductor substrate10.

As above, in the present embodiment, in each of the imaging elements (first imaging element and third imaging element)100that absorb red light and blue light, the slit312is provided in a portion in the vicinity of the center of the imaging element100of the pixel separation wall304that separates the two pixels300aand300bin a case where the imaging element100is viewed from the light receiving surface10aside. Thus, in the present embodiment, in the imaging elements100that absorb red light and blue light and generate charges, an event where light incident on the vicinity of the center of the imaging element100is irregularly reflected by the pixel separation wall304and is incident on an adjacent imaging element100can be suppressed. As a result, in the present embodiment, in the imaging elements100that absorb red light and blue light, crosstalk can be avoided, and eventually degradation of a captured image can be suppressed.

Further, in the present embodiment, it is presumed that in the imaging element (second imaging element)100that absorbs green light, irregular reflection like that described above is less likely to occur; hence, in a case where the imaging element100is viewed from the light receiving surface10aside, the slit312is not provided in the pixel separation wall304that separates the two pixels300aand300b. Thus, in the present embodiment, in the imaging element100that absorbs light having a green wavelength component and generates a charge, an event where a charge generated in the photoelectric conversion section302of one of the two pixels300aand300bflows into the other pixel can be suppressed, and hence the separation ratio of pixels300aand300bcan be improved. As a result, in the present embodiment, in the imaging element100that absorbs light having a green wavelength component, the accuracy of phase difference detection is improved, and the occurrence of point defects on a captured image due to variations in charge inflow can be suppressed. In particular, since mainly the imaging element100that absorbs green light is used at the time of phase difference detection, the improvement of the accuracy of phase difference detection in the imaging element100is favorable.

That is, in the present embodiment, by a configuration in which pixel separation walls304having forms according to the difference in characteristics of light due to the difference in wavelength are provided individually for imaging elements100, degradation of a captured image can be avoided while the accuracy of phase difference detection is improved.

The present embodiment may be modified as follows. Thus, modification examples of the present embodiment will now be described with reference toFIG.5toFIG.7.FIG.5toFIG.7are explanatory diagrams showing configuration examples of a cross section of imaging elements100according to modification examples of the present embodiment, and specifically correspond to a cross section of the imaging element100taken along line B-B′ or line C-C′ shown inFIG.4.

Modification Example 1

First, modification example 1 is described with reference toFIG.5. As shown inFIG.5, in the present modification example 1, the depth of the pixel separation wall304with respect to the light receiving surface10amay be shallower than the depth of the element separation wall310. Further, in the present modification example, as shown inFIG.5, the width of the pixel separation wall304may be thinner than the width of the element separation wall310. In the present modification example 1, by setting the depth and width of the pixel separation wall304as described above, an event where light incident on the vicinity of the center of the imaging element100is irregularly reflected by the pixel separation wall304and is incident on an adjacent imaging element100can be suppressed; thus, crosstalk can be avoided, and eventually degradation of a captured image can be suppressed.

Modification Example 2

Next, modification example 2 is described with reference toFIG.6. As shown inFIG.6, in the present modification example 2, the depth of the pixel separation wall304of the imaging element (first imaging element)100that absorbs red light with respect to the light receiving surface10amay be deeper than the depth of the pixel separation wall304of the imaging element (second imaging element)100that absorbs green light. Further, in the present modification example 2, the depth of the pixel separation wall304of the imaging element (third imaging element)100that absorbs blue light with respect to the light receiving surface10amay be shallower than the depth of the pixel separation wall304of the imaging element (second imaging element)100that absorbs green light.

As described above, the depth with respect to the light receiving surface10aof the region of the semiconductor substrate10where light is absorbed varies with the wavelength of light. Specifically, light having a longer wavelength reaches a deeper region of the semiconductor substrate10. Therefore, for light having a longer wavelength, it is preferable to provide the pixel separation wall304deeper in order to suppress the occurrence of crosstalk like that described above. However, as the depth of the pixel separation wall304becomes deeper, the manufacturing of the imaging element100becomes more difficult, and the possibility of damaging the imaging element100at the time of manufacturing becomes higher. Then, in a case where the imaging element100is damaged, dark current may occur.

Based on the foregoing, in the present modification example, in the imaging element100that absorbs red light of a long wavelength, the occurrence of crosstalk is suppressed by increasing the depth of the pixel separation wall304with respect to the light receiving surface10a. Further, in the present modification example, in the imaging element100that absorbs blue light of a short wavelength, a reduction in yield and the occurrence of dark current are suppressed by reducing the depth of the pixel separation wall304with respect to the light receiving surface10a.

Modification Example 3

Further, modification example 3 will now be described with reference toFIG.7. As shown inFIG.7, the element separation wall310may be provided to penetrate the semiconductor substrate10from the light receiving surface (back surface)10ato the front surface10balong the thickness direction of the semiconductor substrate10. In the present modification example 3, by providing such an element separation wall310, an event where a charge generated in the imaging element100(specifically, the photoelectric conversion section302) flows out to an adjacent other imaging element100can be avoided, and thus the amount of charge that can be stored in the imaging element100can be increased.

Meanwhile, it is presumed that blue light, which has a wavelength shorter than the wavelength of red light, is less likely to be irregularly reflected by the pixel separation wall304than red light. Thus, in the imaging element (third imaging element)100that absorbs light having a blue wavelength component and generates a charge, the slit312may not be provided in the pixel separation wall304in a case where the imaging element100is viewed from the light receiving surface l0aside. Hereinbelow, such a second embodiment of the present disclosure is described with reference toFIG.8.FIG.8is an explanatory diagram showing a planar configuration example of imaging elements100according to the present embodiment, and specifically corresponds to a cross section of the imaging element100taken along line A-A′ shown inFIG.2.

As shown inFIG.8, in the present embodiment, in the imaging element (third imaging element)100that absorbs blue light, the slit312is not provided in the pixel separation wall304in a case where the imaging element100is viewed from the light receiving surface10aside. In the present embodiment, by such a configuration, in the imaging element100that absorbs blue light, an event where a charge generated in the photoelectric conversion section302of one of the two pixels300aand300bflows into the other pixel can be suppressed, and the accuracy (separation ratio) of phase difference detection can be improved.

In an embodiment of the present disclosure, imaging elements100that absorb light of the same color may be arranged on the semiconductor substrate10in units of 2×2 arrays. Thus, a third embodiment of the present disclosure having such an arrangement will now be described with reference toFIG.9.FIG.9is an explanatory diagram showing a configuration example of imaging elements100according to the present embodiment; specifically, the diagram shown in the upper part ofFIG.9corresponds to a cross section of the imaging element100taken along line A-A′ shown inFIG.2, and the diagram shown in the lower part ofFIG.9corresponds to a cross section of the imaging element100taken along line D-D′ shown in the upper part ofFIG.9.

First, as shown in the upper part ofFIG.9, in the present embodiment, a plurality of imaging elements100that absorbs light of the same color is arranged in a 2×2 configuration along the row direction and the column direction, and such four imaging elements100are taken as one array unit. Then, in the present embodiment, array units that absorb red light, green light, and blue light are two-dimensionally arranged in a matrix form on the semiconductor substrate10.

Then, also in the present embodiment, like in the first embodiment, in each of the imaging elements (first imaging element and third imaging element)100that absorb red light and blue light, the slit312is provided in a portion in the vicinity of the center of the imaging element100of the pixel separation wall304in a case where the imaging element100is viewed from the light receiving surface10aside. Further, also in the present embodiment, like in to the first embodiment, in the imaging element (second imaging element)100that absorbs green light, the slit312is not provided in the pixel separation wall304in a case where the imaging element100is viewed from the light receiving surface10aside.

A cross-sectional configuration of imaging elements100in the present embodiment is shown in the lower part ofFIG.9; the cross-sectional configuration is common to the first cross-sectional configuration described above, and thus a detailed description is omitted here.

The present embodiment may be modified as follows. Thus, modification examples of the present embodiment will now be described with reference toFIG.10andFIG.11.FIG.10andFIG.11are explanatory diagrams showing configuration examples of a cross section of imaging elements100according to modification examples of the present embodiment, and specifically correspond to a cross section of the imaging element100taken along line D-D′ shown inFIG.9.

Modification Example 1

First, modification example 1 is described with reference toFIG.10. As shown inFIG.10, in the present modification example 1, the depth of the pixel separation wall304with respect to the light receiving surface10amay be shallower than the depth of the element separation wall310. In the present modification example 1, by setting the depth of the pixel separation wall304as described above, an event where light incident on the vicinity of the center of the imaging element100is irregularly reflected by the pixel separation wall304and is incident on an adjacent imaging element100can be suppressed; thus, crosstalk can be avoided, and eventually degradation of a captured image can be suppressed.

Note that also in the present modification example, like in modification example 1 and modification example 2 of the first embodiment, the width of the pixel separation wall304may be thinner than the width of the element separation wall310, or the depth of the pixel separation wall304with respect to the light receiving surface10amay be varied in accordance with the wavelength of the absorbed light.

Modification Example 2

As shown inFIG.11, the element separation wall310may be provided to penetrate the semiconductor substrate10from the light receiving surface (back surface)10ato the front surface10balong the thickness direction of the semiconductor substrate10. In the present modification example 2, by providing such an element separation wall310, an event where a charge generated in the imaging element100flows out to an adjacent other imaging element100can be avoided, and thus the amount of charge that can be stored in the imaging element100can be increased.

The second embodiment described above may be applied to the third embodiment described above. That is, in the imaging element (third imaging element)100that absorbs light having a blue wavelength component, the slit312may not be provided in the pixel separation wall304in a case where the imaging element100is viewed from the light receiving surface10aside. Hereinbelow, such a fourth embodiment of the present disclosure is described with reference toFIG.12.FIG.12is an explanatory diagram showing a planar configuration example of imaging elements100according to the present embodiment, and specifically corresponds to a cross section of the imaging element100taken along line A-A′ shown inFIG.2.

As shown inFIG.12, in the present embodiment, in the imaging element (third imaging element)100that absorbs blue light, the slit312is not provided in the pixel separation wall304in a case where the imaging element100is viewed from the light receiving surface10aside. In the present embodiment, by such a configuration, in the imaging element100that absorbs blue light, an event where a charge generated in the photoelectric conversion section302of one of the two pixels300aand300bflows into the other pixel can be suppressed, and the accuracy (separation ratio) of phase difference detection can be improved.

In an embodiment of the present disclosure, one imaging element100may include four pixels300ato300d. Thus, a fifth embodiment of the present disclosure having such an arrangement will now be described with reference toFIG.13.FIG.13is an explanatory diagram showing a configuration example of imaging elements100according to the present embodiment; specifically, the diagram shown in the upper part ofFIG.13corresponds to a cross section of the imaging element100taken along line A-A′ shown inFIG.2, and the diagram shown in the lower part ofFIG.13corresponds to a cross section of the imaging element100taken along line E-E′ shown in the upper part ofFIG.13.

As shown in the upper part ofFIG.13, in the present embodiment, one imaging element100includes four pixels300ato300ddivided by twos along the row direction and the column direction by the pixel separation wall304. By using such a structure, the phase difference in the column direction can be detected by individually reading out the amounts of charge generated in the pixels300arranged along the column direction in the drawing, and the phase difference in the row direction can be detected by individually reading out the amounts of charge generated in the pixels300arranged along the row direction in the drawing.

Then, also in the present embodiment, like in the first embodiment, in each of the imaging elements (first imaging element and third imaging element)100that absorb red light and blue light, the slit312is provided in a portion in the vicinity of the center of the imaging element100of the pixel separation wall304, that is, at the center of the four pixels300ato300din a case where the imaging element100is viewed from the light receiving surface10aside. Further, also in the present embodiment, like in the first embodiment, in the imaging element (second imaging element)100that absorbs green light, the slit312is not provided in the pixel separation wall304, that is, at the center of the four pixels300ato300din a case where the imaging element100is viewed from the light receiving surface10aside. Note that the broken line in the diagram shown in the upper part ofFIG.13indicates the on-chip lens200, and in the present embodiment one imaging element100includes one on-chip lens200.

A cross-sectional configuration of imaging elements100in the present embodiment is shown in the lower part ofFIG.13; the cross-sectional configuration is common to the first cross-sectional configuration described above, and thus a detailed description is omitted here.

Note that in the present embodiment, the imaging element100is not limited to including four pixels300ato300d, and may include, for example, eight pixels300; thus, is not particularly limited.

Further, also in the present embodiment, like in modification example 1 and modification example 2 of the first embodiment, the width of the pixel separation wall304may be thinner than the width of the element separation wall310, or the depth of the pixel separation wall304with respect to the light receiving surface10amay be varied in accordance with the wavelength of the absorbed light.

The present embodiment may be modified as follows. Thus, a modification example of the present embodiment will now be described with reference toFIG.14.FIG.14is an explanatory diagram showing a configuration example of a cross section of imaging elements100according to a modification example of the present embodiment, and specifically corresponds to a cross section of the imaging element100taken along line E-E′ shown inFIG.13.

As shown inFIG.14, the element separation wall310may be provided to penetrate the semiconductor substrate10from the light receiving surface (back surface)10ato the front surface10balong the thickness direction of the semiconductor substrate10. In the present modification example, by providing such an element separation wall310, an event where a charge generated in the imaging element100flows out to an adjacent other imaging element100can be avoided, and thus the amount of charge that can be stored in the imaging element100can be increased.

The second embodiment described above may be applied also to the fifth embodiment described above. That is, in the imaging element (third imaging element)100that absorbs light having a blue wavelength component, the slit312may not be provided in the pixel separation wall304in a case where the imaging element100is viewed from the light receiving surface10aside. Hereinbelow, such a sixth embodiment of the present disclosure is described with reference toFIG.15.FIG.15is an explanatory diagram showing a planar configuration example of imaging elements100according to the present embodiment, and specifically corresponds to a cross section of the imaging element100taken along line A-A′ shown inFIG.2.

As shown inFIG.15, in the present embodiment, in the imaging element (third imaging element)100that absorbs blue light, the slit312is not provided in the pixel separation wall304in a case where the imaging element100is viewed from the light receiving surface10aside. In the present embodiment, by such a configuration, in the imaging element100that absorbs blue light, an event where a charge generated in the photoelectric conversion section302of one of the two pixels300aand300bflows into the other pixel can be suppressed, and the accuracy (separation ratio) of phase difference detection can be improved.

Hereinbelow, a seventh embodiment of the present disclosure is described with reference toFIG.16.FIG.16is an explanatory diagram showing a configuration example of imaging elements100according to a seventh embodiment of the present disclosure.

As shown inFIG.16, the angle θ of incidence of light (indicated by the arrow inFIG.16) incident on the pixel array section (light receiving section)30is in the neighborhood of 0 degrees in a central region of the pixel array section30, and increases with proximity to the outer periphery of the pixel array section30. Then, as the angle θ of incidence increases, light becomes more likely to be reflected by the surface (side surface) of the pixel separation wall304perpendicular to the light receiving surface10a, and crosstalk becomes more likely to occur.

Thus, in the present embodiment, as shown inFIG.16, the depth of the pixel separation wall304with respect to the light receiving surface10ais shallowed in the imaging element100in the central region of the pixel array section30, where it is less likely that crosstalk will occur in a mechanism like that described above. Further, in the present embodiment, the depth of the pixel separation wall304is deepened in the imaging element100in the outer peripheral region of the pixel array section30, where it is highly likely that crosstalk will occur in a mechanism like that described above. In other words, in the present embodiment, the depth of the pixel separation wall304with respect to the light receiving surface10ain the imaging element100in the central region is shallower than the depth of the pixel separation wall304in the imaging element100in the outer peripheral region. Thus, in the present embodiment, in the imaging element100in the outer peripheral region, where the angle θ of incidence is large, the occurrence of crosstalk due to the reflection of light by the surface of the pixel separation wall304perpendicular to the light receiving surface10acan be suppressed. Further, in the present embodiment, in the imaging element100in the central region, where it is less likely that crosstalk will occur in a similar mechanism, a reduction in yield and the occurrence of dark current can be suppressed by reducing the depth of the pixel separation wall304.

Hereinbelow, a seventh embodiment of the present disclosure is described with reference toFIG.17.FIG.17is an explanatory diagram showing a configuration example of imaging elements100according to an eighth embodiment of the present disclosure.

As described above, the angle θ of incidence of light (indicated by the arrow inFIG.17) incident on the pixel array section (light receiving section)30is in the neighborhood of 0 degrees in a central region of the pixel array section30, and increases with proximity to the outer periphery of the pixel array section30. Then, as the angle θ of incidence decreases, light becomes more likely to be reflected by the surface (upper surface) of the pixel separation wall304parallel to the light receiving surface10a, and crosstalk becomes more likely to occur.

Thus, in the present embodiment, as shown inFIG.17, the width of the pixel separation wall304is thinned in the imaging element100in the central region of the pixel array section30, where it is highly likely that crosstalk will occur in a mechanism like that described above. Further, in the present embodiment, the width of the pixel separation wall304is thickened in the imaging element100in the outer peripheral region of the pixel array section30, where it is less likely that crosstalk will occur in a mechanism like that described above is low. In other words, in the present embodiment, the width of the pixel separation wall304in the imaging element100in the central region is thinner than the width of the pixel separation wall304in the imaging element100in the outer peripheral region. Thus, in the present embodiment, in the imaging element100in the central region, where the angle θ of incidence is small, the occurrence of crosstalk due to light being reflected by the surface (upper surface) of the pixel separation wall304parallel to the light receiving surface10acan be suppressed. Further, in the present embodiment, in the imaging element100in the outer peripheral region, where it is less likely that crosstalk will occur in a similar mechanism, an event where a charge generated in the photoelectric conversion section302of one of the two pixels300aand300bflows into the other pixel can be suppressed, and the accuracy (separation ratio) of phase difference detection can be improved.

As described hereinabove, in each embodiment of the present disclosure, in the imaging element (first imaging element)100that absorbs red light, in a case where the imaging element100is viewed from the light receiving surface10aside, the slit312is provided in a portion in the vicinity of the center of the imaging element100of the pixel separation wall304that separates the two pixels300aand300b. Thus, in these embodiments, in the imaging element100that absorbs red light and generates a charge, an event where light incident on the vicinity of the center of the imaging element100is irregularly reflected by the pixel separation wall304and is incident on an adjacent imaging element100can be suppressed. As a result, in these embodiments, in the imaging elements100that absorb red light and blue light, crosstalk can be avoided, and eventually degradation of a captured image can be suppressed.

Further, in each embodiment of the present disclosure, it is presumed that in the imaging element (second imaging element)100that absorbs green light, irregular reflection like that described above is less likely to occur; therefore, in a case where the imaging element100is viewed from the light receiving surface10aside, the slit312is not provided in the pixel separation wall304that separates the two pixels300aand300b. Thus, in these embodiments, in the imaging element100that absorbs light having a green wavelength component and generates a charge, an event where a charge generated in the photoelectric conversion section302of one of the two pixels300aand300bflows into the other pixel can be suppressed, and hence the separation ratio of pixels300aand300bcan be improved. As a result, in these embodiments, in the imaging element100that absorbs light having a green wavelength component, the accuracy of phase difference detection is improved, and the occurrence of point defects on a captured image due to variations in charge inflow can be suppressed.

That is, in each embodiment of the present disclosure, by a configuration in which pixel separation walls304having forms according to the difference in characteristics of light due to the difference in wavelength are provided individually for imaging elements100, degradation of a captured image can be avoided while the accuracy of phase difference detection is improved.

Note that although the above embodiments of the present disclosure describe application to a back-side illumination CMOS image sensor structure, the embodiment of the present disclosure is not limited thereto, and may be applied to other structures.

Note that although the above embodiments of the present disclosure describe an imaging element100in which the first conductivity type is an N-type, the second conductivity type is a P-type, and an electron is used as a signal charge, the embodiment of the present disclosure is not limited to such an example. For example, the present embodiment may be applied to an imaging element100in which the first conductivity type is a P-type, the second conductivity type is an N-type, and a hole is used as a signal charge.

Further, in the above embodiments of the present disclosure, the semiconductor substrate10may not necessarily be a silicon substrate, and may be another substrate (for example, a silicon-on-insulator (SOI) substrate, a SiGe substrate, or the like). Further, the semiconductor substrate10may be a structure in which a semiconductor structure or the like is formed on any of such various substrates.

Further, the imaging apparatus1according to the embodiment of the present disclosure is not limited to an imaging apparatus in which a distribution of amounts of incident visible light is sensed and captured as an image. For example, the present embodiment may be applied to an imaging apparatus in which a distribution of amounts of incident infrared rays, X-rays, particles, or the like is captured as an image or an imaging apparatus (physical quantity distribution sensing apparatus) such as a fingerprint detection sensor in which a distribution of another physical quantity such as pressure or capacitance is sensed and captured as an image.

Further, the imaging apparatus1according to the embodiment of the present disclosure can be manufactured by using a method, an apparatus, and conditions used for manufacturing a common semiconductor apparatus. That is, the imaging apparatus1according to the present embodiment can be manufactured by using an existing semiconductor apparatus manufacturing process.

Note that examples of the above method include a physical vapor deposition (PVD) method, a chemical vapor deposition (CVD) method, an atomic layer deposition (ALD) method, and the like. Examples of the PVD method include a vacuum vapor deposition method, an electron beam (EB) vapor deposition method, various sputtering methods (a magnetron sputtering method, a radio frequency (RF)-direct current (DC) coupled bias sputtering method, an electron cyclotron resonance (ECR) sputtering method, a counter target sputtering method, a high frequency sputtering method, and the like), an ion plating method, a laser ablation method, a molecular beam epitaxy (MBE) method, and a laser transfer method. Further, examples of the CVD method include a plasma CVD method, a thermal CVD method, an organic metal (MO) CVD method, and a photo CVD method. Further, other methods include an electrolytic plating method, an electroless plating method, and a spin coating method; an immersion method; a cast method; a micro-contact printing method; a drop cast method; various printing methods such as a screen printing method, an inkjet printing method, an offset printing method, a gravure printing method, and a flexographic printing method; a stamping method; a spray method; and various coating methods such as an air doctor coater method, a blade coater method, a rod coater method, a knife coater method, a squeeze coater method, a reverse roll coater method, a transfer roll coater method, a gravure coater method, a kiss coater method, a cast coater method, a spray coater method, a slit orifice coater method, and a calendar coater method. Further, examples of the patterning method include chemical etching such as a shadow mask, laser transfer, and photolithography, and physical etching using ultraviolet rays, a laser, or the like. In addition, examples of the planarization technology include a chemical mechanical polishing (CMP) method, a laser planarization method, a reflow method, and the like.

<<13. Application Example to Camera>>

The technology according to the present disclosure (the present technology) can be further applied to various products. For example, the technology according to the present disclosure may be applied to a camera or the like. Thus, a configuration example of a camera700as an electronic device to which the present technology is applied will now be described with reference toFIG.18.FIG.18is an explanatory diagram showing an example of a schematic functional configuration of a camera700to which the technology according to the present disclosure (the present technology) can be applied.

As shown inFIG.18, the camera700includes an imaging apparatus702, an optical lens710, a shutter mechanism712, a drive circuit unit714, and a signal processing circuit unit716. The optical lens710causes image light (incident light) from a subject to be formed as an image on an imaging surface of the imaging apparatus702. Thus, signal charges are accumulated in the imaging element100of the imaging apparatus702for a certain period of time. The shutter mechanism712performs opening or closing to control the period of light irradiation and the period of light blocking for the imaging apparatus702. The drive circuit unit714supplies drive signals that control a signal transfer operation of the imaging apparatus702, a shutter operation of the shutter mechanism712, etc. to these components. That is, the imaging apparatus702performs signal transfer on the basis of a drive signal (timing signal) supplied from the drive circuit unit714. The signal processing circuit unit716performs various pieces of signal processing. For example, the signal processing circuit unit716outputs a video signal subjected to signal processing to a storage medium (illustration omitted) such as a memory or to a display section (illustration omitted), for example.

<<14. Application Example to Smartphone>>

The technology according to the present disclosure (the present technology) can be further applied to various products. For example, the technology according to the present disclosure can be applied to a smartphone or the like. Therefore, a configuration example of the smartphone900as an electronic device to which the present technology is applied will be described with reference toFIG.19.FIG.19is a view depicting an example of a schematic functional configuration of the smartphone900to which the technology according to an embodiment of the present disclosure (present technology) can be applied.

As illustrated inFIG.19, the smartphone900includes a central processing unit (CPU)901, a read only memory (ROM)902, and a random access memory (RAM)903. In addition, the smartphone900includes a storage apparatus904, a communication module905, and a sensor module907. Furthermore, the smartphone900includes an imaging apparatus909, a display apparatus910, a speaker911, a microphone912, an input apparatus913, and a bus914. The smartphone900may include a processing circuit such as a digital signal processor (DSP), alternatively or in addition to the CPU901.

The CPU901serves as an arithmetic processing apparatus and a control apparatus, and controls the overall operation or a part of the operation of the smartphone900according to various programs recorded in the ROM902, the RAM903, or the storage apparatus904, or the like. The ROM902stores programs, operation parameters, and the like used by the CPU901. The RAM903primarily stores programs used in execution by the CPU901, and various parameters and the like that change as appropriate when executing such programs. The CPU901, the ROM902, and the RAM903are connected to one another by the bus914. Further, the storage apparatus904is an apparatus for data storage that is an example of a storage unit of the smartphone900. The storage apparatus904includes, for example, a magnetic storage device such as a hard disk drive (HDD), a semiconductor storage device, an optical storage device, or the like. The storage apparatus904stores therein various data and the programs executed by the CPU901, for example, various data acquired from an outside, and the like.

The communication module905is a communication interface including, for example, a communication device for connection to a communication network906. The communication module905may be, for example, a communication card or the like for a wired or wireless local area network (LAN), Bluetooth (registered trademark), Wi-Fi, or a wireless USB (WUSB). Further, the communication module905may also be a router for optical communication, a router for asymmetric digital subscriber line (ADSL), a modem for various types of communication, or the like. For example, the communication module905transmits and receives signals or the like in the Internet or transmits and receives signals or the like to and from another communication device by using a predetermined protocol such as TCP/IP. Further, the communication network906connected to the communication module905is a network established through wired or wireless connection. The communication network906may include, for example, the Internet, a home LAN, infrared communication, satellite communication, or the like.

The sensor module907includes, for example, various sensors such as motion sensors (for example, an acceleration sensor, a gyro sensor, a geomagnetic sensor, etc.), biological information sensors (for example, a pulse sensor, a blood pressure sensor, a fingerprint sensor, etc.), or position sensors (for example, a global navigation satellite system (GNSS) receiver, etc.).

The imaging apparatus909is provided on the front surface of the smartphone900, and can image an object or the like located on the back surface side or the front side of the smartphone900. Specifically, the imaging apparatus909may include an imaging element (illustration omitted) such as a complementary MOS (CMOS) image sensor to which the technology according to the present disclosure (the present technology) can be applied and a signal processing circuit (illustration omitted) that performs imaging signal processing on a signal photoelectrically converted in the imaging element. Further, the imaging apparatus909may further include an optical system mechanism (illustration omitted) including an imaging lens, a diaphragm mechanism, a zoom lens, a focus lens, etc. and a drive system mechanism (illustration omitted) that controls the operation of the optical system mechanism. Then, the imaging element condenses incident light from an object as an optical image, and the signal processing circuit photoelectrically converts the formed optical image in units of pixels, reads out a signal of each pixel as an imaging signal, and performs image processing; thus, a captured image can be acquired.

The display apparatus910is provided on the front surface of the smartphone900, and may be, for example, a display apparatus such as a liquid crystal display (LCD) or an organic electro-luminescence (EL) display. The display apparatus910can display an operation screen, a captured image acquired by the imaging apparatus909described above, etc.

The speaker911can output, for example, a call voice, a voice accompanying video content displayed by the display apparatus910described above, etc. to the user.

The microphone912can collect, for example, a call voice of the user, a voice including a command that starts up a function of the smartphone900, and sounds in the surrounding environment of the smartphone900.

The input apparatus913is a device operated by a user such as a button, a keyboard, a touch panel, and a mouse, for example. The input apparatus913includes an input control circuit that generates input signals on the basis of information which is input by a user to output the generated input signals to the CPU901. A user inputs various types of data to the smartphone900and instructs the smartphone900to perform a processing operation by operating the input apparatus913.

The configuration example of the smartphone900has been described above. Each of the configuration elements described above may include a general purpose component or may include hardware specialized for the function of each of the configuration elements. The configuration may be changed as necessary in accordance with the state of the art at the time of working of the present disclosure.

<<15. Application Example to Endoscopic Surgery System>>

The technology according to the present disclosure (the present technology) can be further applied to various products. For example, the technology according to the present disclosure can be applied to the endoscopic surgery system.

FIG.20is a view showing an example of a schematic configuration of an endoscopic surgery system to which the technology according to an embodiment of the present disclosure (present technology) can be applied.

The endoscope11100includes a lens barrel11101having a region of a predetermined length from a distal end thereof to be inserted into a body cavity of the patient11132, and a camera head11102connected to a proximal end of the lens barrel11101. In the example illustrated, the endoscope11100is illustrated which includes as a rigid endoscope having the lens barrel11101of the hard type. However, the endoscope11100may otherwise be included as a flexible endoscope having the lens barrel of the flexible type.

FIG.21is a block diagram showing an example of a functional configuration of the camera head11102and the CCU11201illustrated inFIG.20.

The imaging unit11402includes imaging elements. The number of imaging elements which is included by the imaging unit11402may be one (single-plate type) or a plural number (multi-plate type). Where the imaging unit11402is configured as that of the multi-plate type, for example, image signals corresponding to respective R, G and B are generated by the imaging elements, and the image signals may be synthesized to obtain a color image. The imaging unit11402may also be configured so as to have a pair of imaging elements for acquiring respective image signals for the right eye and the left eye ready for three dimensional (3D) display. If 3D display is performed, then the depth of a living body tissue in a surgical region can be comprehended more accurately by the surgeon11131. It is to be noted that, where the imaging unit11402is configured as that of stereoscopic type, a plurality of systems of lens units11401is provided corresponding to the individual imaging elements.

Further, the imaging unit11402may not necessarily be provided on the camera head11102. For example, the imaging unit11402may be provided immediately behind the objective lens in the inside of the lens barrel11101.

The driving unit11403includes an actuator and moves the zoom lens and the focusing lens of the lens unit11401by a predetermined distance along an optical axis under the control of the camera head controlling unit11405. Consequently, the magnification and the focal point of a captured image by the imaging unit11402can be adjusted suitably.

In addition, the communication unit11404receives a control signal for controlling driving of the camera head11102from the CCU11201and supplies the control signal to the camera head controlling unit11405. The control signal includes information relating to image capturing conditions such as, for example, information that a frame rate of a captured image is designated, information that an exposure value upon image capturing is designated and/or information that a magnification and a focal point of a captured image are designated.

The control unit11413performs various kinds of control relating to image capturing of a surgical region or the like by the endoscope11100and display of a captured image obtained by image capturing of the surgical region or the like. For example, the control unit11413creates a control signal for controlling driving of the camera head11102.

Further, the control unit11413controls, on the basis of an image signal for which image processes have been performed by the image processing unit11412, the display apparatus11202to display a captured image in which the surgical region or the like is imaged. Thereupon, the control unit11413may recognize various objects in the captured image using various image recognition technologies. For example, the control unit11413can recognize a surgical tool such as forceps, a particular living body region, bleeding, mist when the energy device11112is used and so forth by detecting the shape, color and so forth of edges of objects included in a captured image. The control unit11413may cause, when it controls the display apparatus11202to display a captured image, various kinds of surgery supporting information to be displayed in an overlapping manner with an image of the surgical region using a result of the recognition. Where surgery supporting information is displayed in an overlapping manner and presented to the surgeon11131, the burden on the surgeon11131can be reduced and the surgeon11131can proceed with the surgery with certainty.

Here, while, in the example illustrated, communication is performed by wired communication using the transmission cable11400, the communication between the camera head11102and the CCU11201may be performed by wireless communication.

Hereinabove, an example of an endoscopic surgery system to which the technology according to the present disclosure can be applied is described. The technology according to the present disclosure can be applied to, of the configuration described above, for example, the endoscope11100, (the imaging unit11402of) the camera head11102, (the image processing unit11412of) the CCU11201, or the like.

Note that, although the endoscopic surgery system has been described as an example herein, the technology according to the present disclosure may also be applied to others, for example, a microscope surgery system, and the like.

<<16. Application Example to Mobile Bodies>>

The technology according to the present disclosure (present technology) can be applied to various products. For example, the technology according to the present disclosure may be implemented as apparatuses mounted on any type of mobile bodies such as automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobilities, airplanes, drones, ships, and robots.

FIG.22is a block diagram showing an example of schematic configuration of a vehicle control system as an example of a mobile body control system to which the technology according to an embodiment of the present disclosure can be applied.

The imaging unit12031is an optical sensor that receives light, and which outputs an electric signal corresponding to a received light amount of the light. The imaging unit12031can output the electric signal as an image, or can output the electric signal as information about a measured distance. In addition, the light received by the imaging unit12031may be visible light, or may be invisible light such as infrared rays or the like.

The sound/image output section12052transmits an output signal of at least one of a sound or an image to an output device capable of visually or auditorily notifying information to an occupant of the vehicle or the outside of the vehicle. In the example ofFIG.22, an audio speaker12061, a display section12062, and an instrument panel12063are illustrated as the output device. The display section12062may, for example, include at least one of an on-board display or a head-up display.

FIG.23is a diagram showing an example of the installation position of the imaging unit12031.

Incidentally,FIG.23illustrates an example of imaging ranges of the imaging units12101to12104. An imaging range12111represents the imaging range of the imaging unit12101provided to the front nose. Imaging ranges12112and12113respectively represent the imaging ranges of the imaging units12102and12103provided to the sideview mirrors. An imaging range12114represents the imaging range of the imaging unit12104provided to the rear bumper or the back door. A bird's-eye image of the vehicle12100as viewed from above is obtained by superimposing image data imaged by the imaging units12101to12104, for example.

Hereinabove, an example of a vehicle control system to which the technology according to the present disclosure can be applied is described. The technology according to the present disclosure can be applied to, of the configuration described above, for example, the imaging unit12031or the like.

An imaging apparatus

a first imaging element and a second imaging element each of which converts light to a charge,

in which each of the first and second imaging elements includes:

a plurality of pixels that is provided in a semiconductor substrate and is adjacent to each other;

a pixel separation wall that separates adjacent ones of the plurality of pixels; and

a color filter that is provided above a light receiving surface of the semiconductor substrate and transmits light having a wavelength that is different between the first imaging element and the second imaging element,

the pixel separation wall included in the first imaging element

has a slit at a center of the first imaging element in a case where the imaging apparatus is viewed from a side of the light receiving surface, and

the pixel separation wall included in the second imaging element

does not have a slit at a center of the second imaging element in a case where the imaging apparatus is viewed from a side of the light receiving surface.

The imaging apparatus according to (1), in which

each of the first and second imaging elements includes the two pixels.

The imaging apparatus according to (1), in which

each of the first and second imaging elements includes the four pixels.

each of the first and second imaging elements

further includes an element separation wall that surrounds the plurality of pixels included in each of the first and second imaging elements and separates adjacent imaging elements.

The imaging apparatus according to (4), in which

the pixel separation wall and the element separation wall are provided to penetrate from the light receiving surface to an intermediate place of the semiconductor substrate along a thickness direction of the semiconductor substrate, and

a depth of the pixel separation wall with respect to the light receiving surface is shallower than a depth of the element separation wall.

The imaging apparatus according to (4), in which

the pixel separation wall is provided to penetrate from the light receiving surface to an intermediate place of the semiconductor substrate along a thickness direction of the semiconductor substrate, and

the element separation wall is provided to penetrate the semiconductor substrate along a thickness direction of the semiconductor substrate.

The imaging apparatus according to (5) or (6), in which a depth of the pixel separation wall of the first imaging element with respect to the light receiving surface is deeper than a depth of the pixel separation wall of the second imaging element.

The imaging apparatus according to any one of (4) to (7), in which a width of the pixel separation wall is thinner than a width of the element separation wall in a case where the imaging apparatus is viewed from a side of the light receiving surface.

The imaging apparatus according to any one of (1) to (8),

further including a third imaging element that converts light to a charge,

in which the third imaging element

the plurality of pixels that is provided in the semiconductor substrate and is adjacent to each other;

the pixel separation wall that separates adjacent ones of the plurality of pixels; and

the color filter that is provided above the light receiving surface of the semiconductor substrate and transmits light having a wavelength different from wavelengths of light that the color filters of the first and second imaging elements transmit.

The imaging apparatus according to (9), in which the pixel separation wall included in the third imaging element has a slit at a center of the third imaging element in a case where the imaging apparatus is viewed from a side of the light receiving surface.

The imaging apparatus according to (9), in which the pixel separation wall included in the third imaging element does not have a slit at a center of the third imaging element in a case where the imaging apparatus is viewed from a side of the light receiving surface.

The imaging apparatus according to any one of (9) to (11), in which

the third imaging element

further includes an element separation wall that surrounds the plurality of pixels included in the third imaging element and separates adjacent imaging elements, and

in the third imaging element,

the pixel separation wall and the element separation wall are provided to penetrate from the light receiving surface to an intermediate place of the semiconductor substrate along a thickness direction of the semiconductor substrate, and

a depth of the pixel separation wall with respect to the light receiving surface is shallower than a depth of the element separation wall.

The imaging apparatus according to any one of (9) to (11), in which

the third imaging element

further includes an element separation wall that surrounds the plurality of pixels included in the third imaging element and separates adjacent imaging elements, and

in the third imaging element,

the pixel separation wall is provided to penetrate from the light receiving surface to an intermediate place of the semiconductor substrate along a thickness direction of the semiconductor substrate, and

the element separation wall is provided to penetrate the semiconductor substrate along a thickness direction of the semiconductor substrate.

The imaging apparatus according to (12) or (13), in which a depth of the pixel separation wall of the third imaging element with respect to the light receiving surface is shallower than a depth of the pixel separation wall of the second imaging element.

the imaging apparatus includes a light receiving section including a plurality of imaging elements arranged in a matrix form on the light receiving surface of the semiconductor substrate, and

a depth of the pixel separation wall with respect to the light receiving surface in the imaging element in a central region of the light receiving section is shallower than a depth of the pixel separation wall in the imaging element in an outer peripheral region of the light receiving section.

the imaging apparatus includes a light receiving section including the plurality of imaging elements arranged in a matrix form on the light receiving surface of the semiconductor substrate, and

a width of the pixel separation wall in the imaging element in a central region of the light receiving section is thinner than a width of the pixel separation wall in the imaging element in an outer peripheral region of the light receiving section in a case where the imaging apparatus is viewed from a side of the light receiving surface.

An electronic device

an imaging apparatus including a first imaging element and a second imaging element each of which converts light to a charge,

in which each of the first and second imaging elements includes:

a plurality of pixels that is provided in a semiconductor substrate and is adjacent to each other;

a pixel separation wall that separates adjacent ones of the plurality of pixels; and

a color filter that is provided above a light receiving surface of the semiconductor substrate and transmits light having a wavelength that is different between the first imaging element and the second imaging element,

the pixel separation wall included in the first imaging element

has a slit at a center of the first imaging element in a case where the imaging apparatus is viewed from a side of the light receiving surface, and

the pixel separation wall included in the second imaging element

does not have a slit at a center of the second imaging element in a case where the imaging apparatus is viewed from a side of the light receiving surface.

REFERENCE SIGNS LIST

1Imaging apparatus
10Semiconductor substrate
10aLight receiving surface
10bFront surface
30Pixel array section
32Vertical drive circuit unit
34Column signal processing circuit unit
36Horizontal drive circuit unit
38Output circuit unit
40Control circuit unit
42Pixel drive wiring
44Vertical signal line
46Horizontal signal line
48Input and output terminal
100,100aImaging element
200On-chip lens
202Color filter
204Light blocking section

302Photoelectric conversion section
304Pixel separation wall
310Element separation wall
400a,400bTransfer gate