TECHNICAL FIELD

The present disclosure relates to a solid-state image pickup device and an electronic apparatus and more particularly to a solid-state image pickup device and an electronic apparatus that are suitable to be used in the case where phase-difference detection pixels for realizing an image-surface phase difference AF (Auto Focus) function are arranged.

BACKGROUND ART

Conventionally, an image-surface phase difference AF is known as an AF function system employed in an electronic apparatus represented by a digital camera having a photographing function (e.g., see Patent Literature 1). In a solid-state image pickup device that realizes the image-surface phase difference AF, normal pixels for obtaining pixel signals (color signals) that constitutes an image as well as phase-difference detection pixels for pupil splitting of incident light are arranged at predetermined positions.

In a conventional phase-difference detection pixel, a metal light-shielding film is formed between an on-chip lens and a photoelectric conversion layer. The metal light-shielding film has an opening shifted with respect to an optical axis (optical center) of the on-chip lens. In addition, a light-shielding structure is provided between a pair of phase-difference detection pixels arranged adjacent to each other. The light-shielding structure is for reducing optical color mixing.

A phase-difference signal is calculated on the basis of outputs of the pair of phase-difference detection pixels having openings at different positions (e.g., phase-difference detection pixel opened on left-hand side thereof and phase-difference detection pixel opened on right-hand side thereof). The calculated phase-difference signal is used for controlling focus.

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Patent Application Laid-open No. 2007-304188

DISCLOSURE OF INVENTION

Technical Problem

In the above-mentioned conventional phase-difference detection pixel, the opening is limited by the metal light-shielding film. Therefore, in comparison with a normal pixel, lowering of sensitivity to incident light is inevitable. Thus, an adverse effect in practice can occur. For example, the image-surface phase difference AF cannot be utilized in the case of photographing in a dark place.

Further, pixels will be miniaturized along with an increase in the number of pixels in the solid-state image pickup device in future. In that case, not only reflection of incident light on the metal light-shielding film but also influence of behaviors associated with electromagnetic waves, such as diffraction, become remarkable. For example, lowering of accuracy of phase-difference detection and deterioration of an image quality characteristic due to mixing of reflected/diffracted components into adjacent pixels can occur.

In addition, with the phase-difference detection pixel including the metal light-shielding film, an angle range in which a sensitivity response to a change in angle of incidence is provided is narrow. Therefore, it is difficult for such a phase-difference detection pixel to be used with a lens having a small f-number, an optical zoom lens whose CRA (Chief Ray Angle) is largely variable, or the like.

The present disclosure has been made in view of the above-mentioned circumstances to propose a phase-difference detection pixel capable of avoiding defects such as lowering of sensitivity to incident light and lowering of phase-difference detection accuracy.

Solution to Problem

A solid-state image pickup device as a first aspect of the present disclosure is a solid-state image pickup device in which a normal pixel that generates a pixel signal of an image and a phase-difference detection pixel that generates a pixel signal used in calculation of a phase-difference signal for controlling an image-surface phase difference AF function are arranged in a mixed manner, in which, in the phase-difference detection pixel, a shared on-chip lens for condensing incident light to a photoelectric converter that generates a pixel signal used in calculation of the phase-difference signal is formed for every plurality of adjacent phase-difference detection pixels.

In the normal pixel, an individual on-chip lens for condensing incident light to a photoelectric converter that generates a pixel signal of the image can be formed for each normal pixel.

An inter-pixel light-shielding structure can be provided between the normal pixel and the normal pixel and between the normal pixel and the phase-difference detection pixel.

An inter-pixel light-shielding structure can also be provided between the phase-difference detection pixel and the phase-difference detection pixel.

The phase-difference detection pixel can include an opening light-shielding structure that limits an opening of the photoelectric converter.

In the phase-difference detection pixel, the shared on-chip lens can be formed for every two adjacent pixels.

In the phase-difference detection pixel, two shared on-chip lenses can be formed for every three adjacent pixels.

A boundary between the individual on-chip lens formed in the normal pixel and the shared on-chip lens formed in the phase-difference detection pixel can be approximately rectangular or approximately hexagonal.

A dummy light-condensing element structure can be formed between the individual on-chip lens formed in the normal pixel and the shared on-chip lens formed in the plurality of adjacent phase-difference detection pixels.

The dummy light-condensing element structure can be formed non-symmetrically with respect to the plurality of phase-difference detection pixels that share the shared on-chip lens.

The plurality of phase-difference detection pixels that share the shared on-chip lens can be arranged in a checkerboard pattern.

The phase-difference detection pixel can be linearly arranged in at least either one of a row direction and a column direction.

The phase-difference detection pixel can be arranged in a stripe pattern in at least either one of a row direction and a column direction.

The phase-difference detection pixels arranged in stripes adjacent to each other in the stripe form can have phases shifted from each other.

A color filter having selective sensitivity to three or more kinds of different wavelengths can be provided for each pixel, and the plurality of phase-difference detection pixels that share the shared on-chip lens can include the color filter having selective sensitivity to a same wavelength.

A color filter having selective sensitivity to three or more kinds of different wavelengths can be provided for pixel, and the plurality of phase-difference detection pixels that share the shared on-chip lens can include the color filter having selective sensitivity to different wavelengths.

The phase-difference detection pixel can have a pixel size larger than that of the normal pixel.

All pixels including a color filter having selective sensitivity to a particular wavelength of three or more kinds of different wavelengths can be the phase-difference detection pixels, and an output of the phase-difference detection pixel can be also used as a pixel signal of an image.

The phase-difference detection pixel that shares the shared on-chip lens can have a size that is an integer multiple of that of the normal pixel, the photoelectric converter of the phase-difference detection pixel is divided into a plurality of regions including a central region from which a same oblique incidence characteristic as a photoelectric converter of the normal pixel is obtained, and an output of the central region can be also used as a pixel signal of an image.

The phase-difference detection pixel that shares the shared on-chip lens can have a size that is twice as large as that of the normal pixel, the photoelectric converter of the phase-difference detection pixel is divided into three regions at approximately 0.5:1:0.5, and an output of the region corresponding to 1 of the ratio can be also used as a pixel signal of an image.

The phase-difference detection pixel that shares the shared on-chip lens can have a size that is twice as large as that of the normal pixel, the photoelectric converter of the phase-difference detection pixel is divided into four regions at approximately 0.5:0.5:0.5:0.5, and an addition value of outputs of the regions respectively corresponding to 0.5 and 0.5 at a center of the ratio can be also used as a pixel signal of an image.

An electronic apparatus as a second aspect of the present disclosure is an electronic apparatus including a solid-state image pickup device in which a normal pixel that generates a pixel signal of an image and a phase-difference detection pixel that generates a pixel signal used in calculation of a phase-difference signal for controlling an image-surface phase difference AF function are arranged in a mixed manner, in which, in the phase-difference detection pixel, a shared on-chip lens for condensing incident light to a photoelectric converter that generates a pixel signal used in calculation of the phase-difference signal is formed for every plurality of adjacent phase-difference detection pixels.

Advantageous Effects of Invention

In accordance with the first aspect of the present disclosure, it is possible to realize a solid-state image pickup device that avoids defects such as lowering of the sensitivity to incident light, lowering of the phase-difference detection accuracy, and the like.

In accordance with the second aspect of the present disclosure, it is possible to realize a highly accurate electronic apparatus having an image-surface phase difference AF function.

