TWI697111B - Image sensor and electronic device having the same - Google Patents

Abstract

An image sensor may include: a substrate including a substrate comprising a photoelectric conversion element; a pixel lens formed over the substrate and comprising a plurality of light condensing layers in which a lower layer has a larger area than an upper layer; a color filter layer covering the pixel lens; and an anti-reflection structure formed over the color filter layer.

Description

Image sensor and electronic device with the image sensor

Exemplary embodiments of the present invention relate to a semiconductor device manufacturing technology, and in particular, to an image sensor, which includes a light-concentrating element having a multi-layer stepped structure, and an electronic device having the image sensor.

The priority claimed by the present invention is an application filed with the Korean Intellectual Property Office on April 6, 2015, and its Korean application number is 10-2015-0048436, which is incorporated by reference in its entirety.

An image sensor refers to a device that converts an optical image into an electrical signal. Recently, due to the development of the computer industry and the communication industry, the demand for image sensors with improved performance is in various fields (such as digital cameras, video cameras, personal communication systems (PCS, Personal Communication System), game consoles, security cameras, medical Micro cameras, and robots) have been added.

Various embodiments are directed to an image sensor with improved performance, and an electronic device with the image sensor.

In a specific embodiment, an image sensor may include: a substrate including a photoelectric conversion element; a pixel lens formed above the substrate and including a plurality of light-concentrating layers, the lower layer of which has more layers than the upper layer Large area; a color filter layer covering the pixel lens; and an anti-reflective The radiation structure is formed above the color filter layer. The image sensor may further include a focusing layer provided between the photoelectric conversion element and the pixel lens. And the image sensor may further include an anti-reflection layer formed above the pixel lens.

The focusing layer may have a larger refractive index than the pixel lens. The focusing layer may have the same area or a larger area than the pixel lens. The focal length between the pixel lens and the photoelectric conversion element may be inversely proportional to the thickness of the focusing layer. The pixel lens may have a multi-layer stepped structure. The lower layer exposed by the upper layer may have a smaller width than the wavelength of incident light. The lower layer exposed by the upper layer may have a smaller width than the wavelength of incident light whose color is separated through the color filter layer. The plural light-concentrating layers may have the same shape and be arranged parallel to each other. The upper layer may have the same thickness or less than the lower layer. The upper layer may have the same refractive index or less than the lower layer. The color filter layer can cover the entire surface of the pixel lens and has a flat top surface. The color filter layer may have a smaller refractive index than the pixel lens. The anti-reflection structure may include an anti-reflection layer or a hemispherical lens.

In a specific embodiment, an electronic device may include: an optical system; an image sensor adapted to receive light from the optical system and including a pixel array, wherein a plurality of unit pixels are arranged in a matrix shape; and a signal The processing unit is adapted to process a signal output from the image sensor. Each of these unit pixels may include: a substrate including a photoelectric conversion element; a pixel lens formed above the substrate and including a plurality of light-concentrating layers, wherein the lower layer has a larger area than the upper layer; and a color filter An optical layer covering the pixel lens; and an anti-reflection structure formed above the color filter layer. The electronic device may further include a focusing layer provided between the photoelectric conversion element and the pixel lens.

The focusing layer may have a larger refractive index than the pixel lens. The color filter layer can be compared The pixel lens has a smaller refractive index. The focal length between the pixel lens and the photoelectric conversion element may be inversely proportional to the thickness of the focusing layer. The lower layer exposed by the upper layer may have a smaller width than the wavelength of incident light.

100: pixel array

110: unit pixel

120: Correlated Repeat Sampling (CDS)

130: Analog-to-digital converter (ADC)

140: buffer

150: column driver

160: Timing generator

170: control register

180: ramp signal generator

210: substrate

220: photoelectric conversion element

230: focus layer

240: pixel lens

241: the first light-gathering layer

242: second concentrating layer

250: color filter layer

260: Anti-reflection layer

270: Hemispherical lens

281: The first anti-reflection layer

282: Second anti-reflection layer

283: Third anti-reflection layer

284: Fourth anti-reflection layer

285: Fifth anti-reflection layer

300: Image sensor

310: optical system or optical lens

311: Shutter unit

312: Signal processing unit

313: Drive unit

T: thickness of focusing layer

W1, W2: width

t1: Thickness of lower layer

t2: Thickness of upper layer

D _out : processed image signal

[FIG. 1] is a block diagram schematically illustrating an image sensor according to an embodiment of the present invention.

[FIG. 2A] is a cross-sectional view illustrating a unit pixel of the image sensor according to the specific embodiment of the present invention.

[FIG. 2B] is a cross-sectional view illustrating another specific embodiment of the present invention.

[FIG. 3A] to [FIG. 3C] are perspective views illustrating a focusing layer and a pixel lens according to an embodiment of the present invention.

[FIG. 4A] to [FIG. 4D] are cross-sectional views of an anti-reflection layer in the focusing layer and the pixel lens according to a specific embodiment of the present invention.

[FIG. 5] is a diagram briefly illustrating an electronic device including an image sensor according to an embodiment of the present invention.

Hereinafter, various specific embodiments will be described in more detail with reference to the accompanying drawings. However, the present invention can be embodied in different forms, and should not be construed as being limited to the specific embodiments set forth herein. Rather, these specific embodiments are provided to make the disclosed content thorough and complete, and fully convey the scope of the present invention to those having ordinary knowledge in the art. Throughout the disclosure, the same element symbols refer to similar parts throughout the various drawings and specific embodiments of the present invention.

The drawings are not necessarily drawn to scale, and in some examples, the scale may be enlarged The features of these specific embodiments are clearly illustrated. When the first layer refers to "on" the second layer "on" or "on" the substrate, it not only refers to the case where the first layer is directly formed on the second layer or the substrate , And refers to the situation where the third layer exists between the first layer and the second layer or the substrate.

The embodiments of the present invention provide an image sensor with improved performance, and an electronic device having the image sensor. As the light collection efficiency in the unit pixel improves, the performance of the image sensor improves accordingly. Generally, an image sensor may include a plurality of unit pixels. Each of these unit pixels may include a hemispherical micro lens (ML, Micro lens), which is installed above a photoelectric conversion element. Through the microlens, incident light can be condensed and transmitted to the photoelectric conversion element. The light collection efficiency of the unit pixel can be determined according to the quality of the microlens. The light collection efficiency can be controlled according to a focal length between the microlens and the photoelectric conversion element.

In conventional microlenses, the focal length between the microlens and the photoelectric conversion element may be changed during the process of changing the curvature of the microlens. Therefore, it is not easy to control the focal length.

The microlens can be formed by a process of reflowing a lens forming material (such as a resist). In this process, it is difficult to form a hemisphere with the required curvature. Furthermore, since the microlens is formed above a color filter layer, the applicable materials are limited. In addition, this reflow process may require high cost, may be formed only in a hemispherical shape, and may have difficulty in forming microlenses having a symmetrical and uniform shape. This may increase crosstalk.

The following specific embodiments of the present invention provide an image sensor having improved light collection efficiency in a unit pixel, and an electronic device having the image sensor. For this structure, each of these unit pixels may include a pixel lens having a plurality of light-concentrating layers formed above a photoelectric conversion element. The lower layer of the plurality of light concentrating layers has a larger area or critical dimension (CD) than the upper layer of the plurality of light concentrating layers. Therefore, the pixel lens may have a multilayer stepped structure. The pixel lens with a multi-layer stepped structure exhibits sub-wavelength optical or sub-wavelength effects, and can condense incident light like a hemispherical microlens. The pixel lens can effectively condense light in a limited area. Therefore, the pixel lens according to the specific embodiment has advantages in enhancing the integration of the image sensor, and can easily change the focal length. According to this sub-wavelength optics, the optical effect can be obtained in a spatial scale that is less than one-half wavelength of the incident light.

FIG. 1 is a block diagram schematically illustrating an image sensor according to a specific embodiment of the present invention.

As illustrated in FIG. 1, the image sensor according to an embodiment of the present invention may include a pixel array 100, a correlated double sampling (CDS) 120, and an analog-digital converter (ADC) converter) 130, a buffer 140, a column driver 150, a timing generator 160, a control register 170, and a ramp signal generator 180. The pixel array 100 may include a plurality of unit pixels 110, which are arranged in a matrix shape.

The timing generator 160 may generate one or more control signals for controlling the column driver 150, the CDS 120, the ADC 130, and the ramp signal generator 180. The control register 170 may generate one or more control signals for controlling the ramp signal generator 180, the timing generator 160, and the buffer 140.

The column driver 150 may drive the pixel array 100 based on column lines. For example, the column driver 150 may generate a selection signal for selecting any one of the plural column lines. Each unit pixel 110 can sense the incident light and output the image reset signal and the image signal to the CDS 120 through the row line. CDS 120 can sample the image reset signal and the image signal.

The ADC 130 may compare the ramp signal output from the ramp signal generator 180 with the sampling signal output from the CDS 120, and output a comparison signal. According to the clock supplied from the timing generator 160 Signal, the ADC 130 can count the level transition time of the comparison signal, and output the count value to the buffer 140. The ramp signal generator 180 can be operated under the control of the timing generator 160.

The buffer 140 may store the complex digital signals output from the ADC 130, and then sense and amplify the digital signals. Therefore, the buffer 140 may include a memory (not shown) and a sense amplifier (not shown). The memory can be used to store count values. These count values are related to the signal output from the plural unit pixels 110. The sense amplifier can be used to sense and amplify the count values output from the memory.

In the above-mentioned image sensor, each of these unit pixels may include a pixel lens, which can improve the light collection efficiency. Hereinafter, the unit pixel including the one-pixel lens will be explained in detail with reference to the attached drawings.

2A is a cross-sectional view illustrating a unit pixel of an image sensor according to the specific embodiment of the present invention, and FIG. 2B is a cross-sectional view illustrating another specific embodiment of the present invention. 3A to 3C are perspective views illustrating an example of a focusing layer and a pixel lens according to the specific embodiment of the present invention.

As illustrated in FIGS. 2A, 2B, and 3A to 3C, each unit pixel 110 may include a substrate 210, a focusing layer 230, a pixel lens 240, a color filter layer 250, and an anti-reflection structure. The substrate 210 may include a photoelectric conversion element 220. The focusing layer 230 may be formed above the substrate 210. The pixel lens 240 may be formed above the focusing layer 230 and include a plurality of light-concentrating layers. In these complex light-concentrating layers, the lower layer has a larger area or critical dimension (CD) than the upper layer. The color filter layer 250 may be formed above the focusing layer 230 to cover the pixel lens 240. The anti-reflection structure may be formed above the color filter layer 250.

In this embodiment, the pixel lens 240 may include a first light-concentrating layer 241 formed above the focusing layer 230, and a second light-concentrating layer 242 formed above the first light-concentrating layer 241, It has a smaller area than the first light-concentrating layer 241. The first light-concentrating layer 241 may form the lower layer, and the second light-concentrating layer 242 may form the upper layer. Therefore, the first light concentrating layer and the lower layer may be represented by the same element symbol 241, and the second light concentrating layer and the upper layer may be represented by the same element symbol 242.

The substrate 210 may include a semiconductor substrate. The semiconductor substrate may have a single crystal state and include a silicon-containing material. That is, the substrate 210 may include a single crystal silicon-containing material.

The photoelectric conversion element 220 may include a photodiode. For example, the photoelectric conversion element 220 formed above the substrate 210 may include a plurality of vertically stacked photoelectric conversion layers (not shown). Each of these photoelectric conversion layers can be used as a photodiode including an N-type impurity region and a P-type impurity region.

The focusing layer 230 can be used to adjust the distance that the incident light condensed through the pixel lens 240 reaches the photoelectric conversion element 220, that is, the focal length. Due to the focusing layer 230, the focal length can be adjusted without changing the curvature, which is different from the conventional device in which the focal length is adjusted using a hemispherical microlens with a given curvature. Furthermore, a shorter focal length can be set in a limited space. The focal length may be inversely proportional to the thickness T of the focusing layer 230. For example, the focal length may be shortened as the thickness T of the focusing layer 230 increases, and extend as the thickness T of the focusing layer 230 decreases.

In order to efficiently transmit the incident light condensed through the pixel lens 240 to the photoelectric conversion element 220, the focusing layer 230 may have the same area or a larger area than the pixel lens 240. The focusing layer 230 may have a shape corresponding to each unit pixel 110. Therefore, between adjacent unit pixels 110, the focusing layer 230 may be in contact with each other. For example, the focusing layer 230 may have a rectangular shape.

In order to transmit the incident light condensed through the pixel lens 240 to the photoelectric conversion element 220 more efficiently, the focusing layer 230 may have a larger refractive index than the pixel lens 240. As for the focusing layer 230, any material having a larger refractive index than the pixel lens 240 may be suitable.

Since the focusing layer 230 is positioned at the bottom of the color filter layer 250, Various materials used in the conductor manufacturing process are applicable. For example, the transparent material applicable as the focusing layer 230 may include inorganic materials (such as silicon oxide, silicon nitride, and titanium nitride). The focusing layer 230 may have a single-layer structure or a multi-layer structure in which transparent materials having different refractive indexes are stacked. When the focusing layer 230 has a multi-layer structure, the refractive index of the focusing layer 230 may vary according to the position. The refractive index of the layer at a lower level may have a higher refractive index than the layer at a higher level.

The pixel lens 240 may serve as a light-condensing element to condense incident light. In order to improve the light collection efficiency, the pixel lens 240 may have a multi-layer structure in which two or more light collection layers 241 and 242 are stacked. The upper layer 242 may have a smaller area or critical dimension (CD) than the lower layer 241. Therefore, the pixel lens 240 may have a multi-layer stepped structure. When the pixel lens 240 has a multi-layer stepped structure, the difference in width, that is, the widths W1 and W2 may be smaller than the wavelength of incident light. That is, in the pixel lens, the lower layer exposed by the upper layer has a smaller width than the wavelength of incident light. More specifically, the difference in width, that is, the widths W1 and W2 between the upper layer 242 and the lower layer 241 may be smaller than the wavelength of the incident light whose color is separated by the color filter layer 250. Through this structure, the pixel lens 240 having a multi-layered stepped structure can condense light like a conventional hemispherical lens. This is based on this sub-wavelength optics. The widths W1 and W2 form step widths between the upper layer 242 and the lower layer 241 at both ends, and may be equal to each other (W1=W2) or different from each other (W1≠W2).

The plurality of light-concentrating layers 241 and 242 may have the same shape and be arranged parallel to each other. Specifically, the complex light-concentrating layers 241 and 242 may have a circular shape, a polygonal shape including a quadrangle, or the like.

To further improve the light collection efficiency, the thickness t2 of the upper layer 242 may be equal to the thickness t1 of the lower layer 241 (t1=t2), or smaller than the thickness t1 of the lower layer 241 (t1>t2). Furthermore, in order to further improve the light collection efficiency, the upper layer 242 may have the same refractive index or a lower refractive index than the lower layer 241. plural The light-concentrating layers 241 and 242 may include a transparent material. When the upper layer 242 and the lower layer 241 have the same refractive index, the upper layer 242 and the lower layer 241 may be formed of the same material.

Since the plurality of light-concentrating layers 241 and 242, that is, the pixel lens 240 is positioned at the bottom of the color filter layer 250, various materials used in general semiconductor manufacturing processes are applicable. For example, the transparent materials applicable as the plurality of light-concentrating layers 241 and 242 may include inorganic materials (such as silicon oxide, silicon nitride, and titanium nitride). The light-concentrating layers 241 and 242 may have a single-layer structure or a multi-layer structure in which transparent materials having different refractive indexes are stacked. When the plural light-concentrating layers are provided, the refractive indexes of the light-concentrating layers may vary according to positions. The refractive index of the light concentrating layer at a higher level may be smaller than that of the light concentrating layer at a lower level. That is, the refractive indexes of the light-concentrating layers may increase as the light-concentrating layers are adjacent to the photoelectric conversion element 220 or the focusing layer 230.

The color filter layer 250 for color separation may be formed over the focusing layer 230 to cover the pixel lens 240 and have a flat surface. Since the color filter layer 250 contacts the pixel lens 240 and covers the pixel lens 240, the light transmission between the color filter layer 250 and the pixel lens 240 can be improved. That is, the light collection efficiency can be improved. The color filter layer 250 may include a red filter, a green filter, a blue filter, a cyan filter, a yellow filter, a magenta filter, and an infrared filter (infrared pass filter), an infrared cutoff filter, a white filter, or a combination thereof. To further improve the light collection efficiency, the color filter layer 250 may have a smaller refractive index than the pixel lens 240.

The anti-reflection structure may be formed above the color filter layer 250, and includes an anti-reflection layer 260 or a hemispherical lens 270. The anti-reflection layer 260 may include two or more material layers, which have different refractive indexes and are alternately stacked one or more times. The hemispherical lens 270 not only prevents reflection of incident light, but also condenses light incident on the pixel lens 240.

As the image sensor having the above-described structure includes the pixel lens 240 having a multilayer stepped structure, the light collection efficiency in the unit pixel 110 can be improved. Furthermore, as the color filter layer 250 has a shape that can cover the pixel lens 240, the light collection efficiency in the unit pixel 110 can be further improved. As the light collection efficiency in the unit pixel 110 is improved, the quantum efficiency in the photoelectric conversion element 220 can also be improved. As a result, the performance of the image sensor can be improved.

In the image sensor according to a specific embodiment of the present invention, the focusing layer and the pixel lens may have a structure in which a plurality of material layers are stacked. Therefore, the anti-reflection layer can be easily installed between these layers. The anti-reflection layer can prevent incident light from being reflected from the surface, thereby preventing a decrease in light collection efficiency due to a decrease in light intensity. However, in the image sensor including hemispherical microlenses, the formation positions of the anti-reflection layers can be limited. Hereinafter, the anti-reflection layers will be described in detail with reference to FIGS. 4A to 4D. The first to fifth anti-reflection layers illustrated in FIGS. 4A to 4D may respectively indicate that two or more material layers with different refractive indexes are alternately stacked one or more times.

4A to 4D are cross-sectional views illustrating the anti-reflection layers according to an embodiment of the invention.

First, as illustrated in FIG. 4A, the first anti-reflection layer 281 may be formed under the focusing layer 230. Specifically, the first anti-reflection layer 281 may be formed between the focusing layer 230 and the substrate including the photoelectric conversion element. Furthermore, the second anti-reflection layer 282 may be formed between the focusing layer 230 and the pixel lens 240. The first anti-reflection layer 281 and the second anti-reflection layer 282 may be formed through a deposition process before and after the focusing layer 230 is formed.

As illustrated in FIG. 4B, the third anti-reflection layer 283 may be formed above the pixel lens 240. Specifically, the third anti-reflection layer 283 may be formed between the pixel lens 240 and the color filter layer. The third anti-reflective layer 283 may be formed through a deposition process after the pixel lens 240 is formed. The deposition process can The third anti-reflection layer 283 has a constant thickness along the surface of the structure.

As illustrated in FIG. 4C, the fourth anti-reflection layer 284 may be formed above the first light-concentrating layer 241. The fifth anti-reflection layer 285 may be formed above the second light-concentrating layer 242. The fourth anti-reflection layer 284 and the fifth anti-reflection layer 285 may be simultaneously formed as the first and second light-concentrating layers 241 and 242 are formed, respectively. When the first light-concentrating layer 241 and the second light-concentrating layer 242 have different refractive indexes from each other, the fourth anti-reflection layer 284 may be on the boundary surface between the first light-concentrating layer 241 and the second light-concentrating layer 242 Prevent surface reflections.

As illustrated in FIG. 4D, all of the first anti-reflection layer 281 to the fifth anti-reflection layer 285 may be formed. In the image sensor according to a specific embodiment of the present invention, the focusing layer 230 and the pixel lens 240 may have a structure in which a plurality of material layers are stacked. Therefore, the anti-reflection layer can be easily installed between these layers. Such a structure can further improve the light collection efficiency.

The image sensor according to an embodiment of the invention can be used in various electronic devices or systems. Hereinafter, the image sensor according to a specific embodiment of the present invention applicable to a camera will be explained with reference to FIG. 5.

FIG. 5 is a diagram briefly illustrating an electronic device including an image sensor according to an embodiment of the present invention. Referring to FIG. 5, the electronic device including the image sensor according to an embodiment of the present invention may include a camera capable of shooting still images or moving images. The electronic device may include an optical system or optical lens 310, a shutter unit 311, a driving unit 313 for controlling/driving the image sensor 300 and the shutter unit 311, and a signal processing unit 312.

The optical system 310 can guide image light, that is, incident light, from the object to the pixel array 100 of the image sensor 300 (refer to FIG. 1 ). The optical system 310 may include a plurality of optical lenses. The shutter unit 311 may control the light irradiation period and the light blocking period for the image sensor 300. The driving unit 313 can control the transmission operation of the image sensor 300 and the shutter operation of the shutter unit 311. The signal processing unit 312 can process the signal output from the image sensor 300 in various ways. The processed image signals D _out can be stored in a storage medium (such as a memory, or output to a monitor or the like).

According to a specific embodiment of the present invention, an image sensor may include a pixel lens to improve the light collection efficiency in the unit pixel. Furthermore, as the color filter layer has a shape that can cover the pixel lens, the light collection efficiency in the unit pixel can be further improved.

According to a specific embodiment, the light collection efficiency in the unit pixel is improved and the quantum efficiency in the photoelectric conversion element is improved. As a result, the performance of the image sensor can be improved.

Although various specific embodiments have been described for illustrative purposes, it should be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention as defined in the following patent applications .

110: unit pixel

210: substrate

220: photoelectric conversion element

230: focus layer

240: pixel lens

241: the first light-gathering layer

242: second concentrating layer

250: color filter layer

260: Anti-reflection layer

W1, W2: width

T: thickness of focusing layer

t1: Thickness of lower layer

t2: Thickness of upper layer

Claims (18)

An image sensor includes: a substrate including a photoelectric conversion element; a pixel lens formed above the substrate and including a plurality of light-concentrating layers, a lower layer of which has a larger area than an upper layer; A color filter layer covering the pixel lens; and an anti-reflection structure formed above the color filter layer; wherein each of the light-concentrating layers has a flat surface and is exposed by the upper layer The lower layer has a smaller width than the wavelength of incident light, and the upper layer has a smaller refractive index than the lower layer, and the upper layer and the lower layer are formed of the same material. The image sensor as described in item 1 of the patent application scope further includes: a focusing layer provided between the photoelectric conversion element and the pixel lens. The image sensor as described in item 2 of the patent application scope, wherein the focusing layer has a larger refractive index than the pixel lens. The image sensor as described in item 2 of the patent application range, wherein the focusing layer has the same area or a larger area than the pixel lens. The image sensor as described in item 2 of the patent application scope, wherein a focal length between the pixel lens and the photoelectric conversion element is inversely proportional to the thickness of the focusing layer. The image sensor as described in item 1 of the patent application scope, wherein the pixel lens has a multi-layer stepped structure. An image sensor as described in item 1 of the patent application range, wherein the lower layer exposed by the upper layer has a smaller width than the wavelength of incident light whose color is separated by the color filter layer. The image sensor as described in item 1 of the patent application, wherein the plurality of light-concentrating layers have the same shape and are arranged parallel to each other. An image sensor as described in item 1 of the patent application range, wherein the upper layer has the same thickness or a smaller thickness than the lower layer. The image sensor as described in item 1 of the patent application, wherein the upper layer has the same refractive index or a smaller refractive index than the lower layer. The image sensor as described in item 1 of the patent application scope further includes: an anti-reflection layer formed above the pixel lens. The image sensor as described in item 1 of the patent application range, wherein the color filter layer covers the entire surface of the pixel lens and has a flat top surface. The image sensor as described in item 1 of the patent application range, wherein the color filter layer has a smaller refractive index than the pixel lens. The image sensor as described in item 1 of the patent application scope, wherein the anti-reflection structure includes an anti-reflection layer or a hemispherical lens. An electronic device includes: an optical system; an image sensor, which is suitable for receiving light from the optical system and includes a pixel array, wherein a plurality of unit pixels are arranged in a matrix shape; and a signal processing unit, which is suitable For processing a signal output from the image sensor, each of the unit pixels includes: a substrate including a photoelectric conversion element; A pixel lens formed above the substrate and including a plurality of light-concentrating layers, a lower layer of which has a larger area than an upper layer; a color filter layer covering the pixel lens; and an anti-reflection structure, It is formed above the color filter layer; wherein each of the light-concentrating layers has a flat surface, and the lower layer exposed by the upper layer has a smaller width than the wavelength of incident light, and the upper part The layer has a smaller refractive index than the lower layer, and the upper layer and the lower layer are formed of the same material. The electronic device as described in item 15 of the patent application scope further includes: a focusing layer provided between the photoelectric conversion element and the pixel lens. The electronic device as described in item 16 of the patent application range, wherein the focusing layer has a larger refractive index than the pixel lens, and wherein the color filter layer has a smaller refractive index than the pixel lens. An electronic device as described in item 16 of the patent application range, wherein a focal length between the pixel lens and the photoelectric conversion element is inversely proportional to the thickness of the focusing layer.

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