KR102394277B1 - Image sensor and electronic device having the same - Google Patents

Abstract

An image sensor and an electronic device having the same are provided. An image sensor according to an embodiment of the present invention includes a substrate including a photoelectric conversion element; a pixel lens formed on the substrate and including a plurality of light collecting layers having a lower area larger than an upper layer; a color filter layer covering the pixel lens; and an anti-reflection structure formed on the color filter layer.

Description

Image sensor and electronic device having same

The present invention relates to a semiconductor device manufacturing technology, and more particularly, to an image sensor including a light collecting member having a multi-layered step shape, and an electronic device having the same.

An image sensor is a device that converts an optical image into an electrical signal. Recently, with the development of the computer industry and communication industry, the demand for image sensors with improved performance in various fields such as digital cameras, camcorders, PCS (Personal Communication System), game devices, security cameras, medical micro cameras, and robots is increasing. there is.

An embodiment of the present invention provides an image sensor with improved performance and an electronic device having the same.

An image sensor according to an embodiment of the present invention includes a substrate including a photoelectric conversion element; a pixel lens formed on the substrate and including a plurality of light collecting layers having a lower area larger than an upper layer; a color filter layer covering the pixel lens; and an anti-reflection structure formed on the color filter layer. In addition, it may further include a focusing layer inserted between the photoelectric conversion element and the pixel lens.

The focusing layer may have a refractive index greater than that of the pixel lens. The focusing layer may have a larger area than the pixel lens. A focal length between the pixel lens and the photoelectric conversion element may be inversely proportional to a thickness of the focusing layer. The pixel lens may have a multi-layered step shape. In the pixel lens, a line width of the lower layer exposed by the upper layer may be smaller than a wavelength of incident light. In the pixel lens, a line width of the lower layer exposed by the upper layer may be smaller than a wavelength of incident light that has passed through the color filter layer and is color-separated. In the pixel lens, each of the plurality of light collecting layers may have the same shape and may be disposed parallel to each other. In the pixel lens, the thickness of the upper layer may be the same as or thinner than the thickness of the lower layer. In the pixel lens, the refractive index of the upper layer may be the same as or smaller than the refractive index of the lower layer. An anti-reflection layer formed on the pixel lens may be further included. The color filter layer may cover an entire surface of the pixel lens and may have a flat 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 formed on the color filter layer and in which two or more material layers having different refractive indices are alternately stacked at least once. The anti-reflection structure may include a hemispherical lens formed on the color filter layer.

An electronic device according to an embodiment of the present invention includes an optical system; an image sensor receiving light from the optical system and including a pixel array in which a plurality of unit pixels are arranged in a matrix structure; and a signal processing unit configured to perform a signal processing operation on the signal output from the image sensor, wherein each of the plurality of unit pixels includes: a substrate including a photoelectric conversion element; a pixel lens formed on the substrate and including a plurality of light collecting layers having a lower area larger than an upper layer; a color filter layer covering the pixel lens; and an anti-reflection structure formed on the color filter layer. In addition, it may further include a focusing layer inserted between the photoelectric conversion element and the pixel lens.

The focusing layer may have a higher refractive index than that of the pixel lens, and the color filter layer may have a smaller refractive index than that of the pixel lens. A focal length between the pixel lens and the photoelectric conversion element may be inversely proportional to a thickness of the focusing layer. In the pixel lens, a line width of the lower layer exposed by the upper layer may be smaller than a wavelength of incident light. The antireflection structure may include an antireflection layer or a hemispherical lens in which two or more material layers having different refractive indices are alternately stacked at least once.

The present technology based on the means for solving the above-described problems can improve light collection efficiency in a unit pixel by providing a pixel lens. In addition, since the color filter layer has a shape that covers the pixel lens, it is possible to further improve light collection efficiency in the unit pixel.

As such, as the light collection efficiency in the unit pixel is improved, the quantum efficiency in the photoelectric conversion device may also be improved. As a result, the performance of the image sensor can be improved.

1 is a block diagram schematically showing an image sensor according to an embodiment of the present invention;
2A is a cross-sectional view illustrating a unit pixel of an image sensor according to an embodiment of the present invention;
Fig. 2B is a cross-sectional view showing a modification of Fig. 2A;
3A to 3C are perspective views illustrating an example of a focusing layer and a pixel lens according to an embodiment of the present invention;
4A to 4D are cross-sectional views illustrating formation positions of a focusing layer and an anti-reflection layer in a pixel lens according to an embodiment of the present invention.
5 is a diagram schematically illustrating an electronic device having an image sensor according to an embodiment of the present invention.

Hereinafter, the most preferred embodiment of the present invention will be described with reference to the drawings in order to describe in detail enough that a person of ordinary skill in the art can easily implement the technical idea of the present invention. The drawings are not necessarily drawn to scale, and in some examples, the proportions of at least some of the structures illustrated in the drawings may be exaggerated in order to clearly show the features of the embodiments. When a multi-layer structure having two or more layers is disclosed in the drawings or detailed description, the relative positional relationship or arrangement order of the layers as shown only reflects a specific embodiment, and thus the present invention is not limited thereto, and the relative positions of the layers The relationship or arrangement order may be different. Further, the drawings or detailed description of a multi-layer structure may not reflect all layers present in a particular multi-layer structure (eg, one or more additional layers may be present between the two layers shown). For example, in the multilayer structure of the drawings or detailed description, where a first layer is on a second layer or on a substrate, it indicates that the first layer can be formed directly on the second layer or directly on the substrate. Furthermore, it may indicate the case where one or more other layers are present between the first layer and the second layer or between the first layer and the substrate.

An embodiment of the present invention, which will be described later, provides an image sensor with improved performance and an electronic device having the same. Here, the image sensor with improved performance may mean that light collection efficiency in a unit pixel is improved. In general, an image sensor has a plurality of unit pixels, and a micro lens (ML) of a semi-spherical type to correspond to each of the plurality of unit pixels is disposed on an upper portion of a photoelectric conversion element. is installed. Incident light is condensed to a photoelectric conversion element through a micro lens, and light collection efficiency in a unit pixel is determined by the micro lens. Here, the light collection efficiency may be controlled according to a focal length between the microlens and the photoelectric conversion element.

However, since the known microlens varies the focal length between the microlens and the photoelectric conversion element by changing the curvature, it is not easy to adjust the focal length. This is because the microlens is formed by a method of reflowing a lens forming material, for example, a resist, so the process is complicated and it is difficult to implement a hemispherical shape having a desired curvature. In addition, since the microlens is formed on the color filter layer, it is another reason that the applicable materials are limited. In addition, the reflow method is expensive, can implement only a hemispherical shape, and it is difficult to form a microlens having a symmetrical and uniform shape. This also acts as a cause of increasing crosstalk. And, since the microlens is formed on the color filter layer, the applicable materials are limited.

Accordingly, embodiments to be described below provide an image sensor having improved light collection efficiency in a unit pixel by overcoming the disadvantages of the microlens, and an electronic device having the same. To this end, each of the plurality of unit pixels may include a pixel lens formed on the photoelectric conversion element and configured with a plurality of light collecting layers having a lower area or line width greater than an upper layer. Accordingly, the pixel lens may have a multi-layered step shape. A pixel lens having a multi-layered step shape can collect incident light like a hemispherical micro lens according to sub-wavelength optics or sub-wavelength effect. In addition, effective light collection is possible within a limited area in response to an increase in the degree of integration of the image sensor, and the focal length can be easily varied. For reference, sub-wavelength optics is a study of optical effects at a spatial scale smaller than a wavelength, and it is known that the minimum spatial scale at which an optical effect can be obtained corresponds to half the wavelength (λ/2), but sub-wavelength optics According to wavelength optics, optical effects can be obtained even at spatial scales smaller than half a wavelength.

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

1, the image sensor according to the embodiment includes a pixel array 100 in which a plurality of unit pixels 110 are arranged in a matrix structure, correlated double sampling (CDS, 120), analog digital converter (ADC) 130, buffer 140, row driver 150, timing generator 160, control register 170 and ramp signal A generator (ramp signal generator, 180) may be included.

The timing generator 160 may generate one or more control signals for controlling the operation of each of the row driver 150 , the correlated double sampling 120 , the analog-to-digital converter 130 , and the ramp signal generator 180 . The control register 170 may generate one or more control signals for controlling operations of the ramp signal generator 180 , the timing generator 160 , and the buffer 140 , respectively.

The row driver 150 may drive the pixel array 100 in a row line unit. For example, the row driver 150 may generate a selection signal for selecting any one row line from among a plurality of row lines. Each of the plurality of unit pixels 110 may sense incident light and output an image reset signal and an image signal as the correlated double sampling 120 through a column line. The correlated double sampling 120 may perform sampling on each of the received image reset signal and the image signal.

The analog-to-digital converter 130 may compare the ramp signal output from the ramp signal generator 180 and the sampling signal output from the correlated double sampling 120 with each other to output a comparison signal. A level transition time of the comparison signal may be counted according to a clock signal provided from the timing generator 160 , and the count value may be output to the buffer 140 . The ramp signal generator 180 may operate under the control of the timing generator 160 .

The buffer 140 may store each of a plurality of digital signals output from the analog-to-digital converter 130 , and then sense and amplify each of them and output them. Accordingly, the buffer 140 may include a memory (not shown) and a sense amplifier (not shown). The memory is for storing a count value, and the count value means a count value associated with signals output from the plurality of unit pixels 110 . The sense amplifier may sense and amplify each count value output from the memory.

In the above-described image sensor, the plurality of unit pixels may include a pixel lens capable of improving light collection efficiency. Hereinafter, a unit pixel including a pixel lens will be described in detail with reference to the drawings.

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

As shown in FIGS. 2A, 2B and 3A to 3C, each of the plurality of unit pixels 110 includes a substrate 210 including a photoelectric conversion element 220, and a focusing layer formed on the substrate 210 ( 230), the pixel lens 240 formed on the focusing layer 230 and including a plurality of light collecting layers in which the upper layer has a smaller area or line width than the lower layer, is formed on the focusing layer 230 to form the pixel lens 240 It may include a covering color filter layer 250 and anti-reflection structures 260 and 270 formed on the color filter layer 250 . In the present embodiment, the pixel lens 240 includes a first light collecting layer 241 formed on the focusing layer 230 and a second light collecting layer 241 formed on the first light collecting layer 241 and having a smaller area than the first light collecting layer 241 . The pixel lens 240 composed of two light collecting layers 242 was exemplified. Here, the first light collecting layer 241 is a lower layer, and the second light collecting layer 242 is an upper layer. Accordingly, the first light collecting layer 241 and the lower layer, and the second light collecting layer 242 and the upper layer will use the same reference numerals.

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

The photoelectric conversion device 220 may include a photodiode. For example, the photoelectric conversion device 220 formed on the substrate 210 may include a plurality of vertically overlapping photoelectric conversion layers (not shown), and each of the plurality of photoelectric conversion layers includes an N-type impurity region and a P-type impurity region. It may be a photodiode including an impurity region.

The focusing layer 230 serves to adjust the distance at which the incident light focused through the pixel lens 240 reaches the photoelectric conversion element 220 , that is, a focal length. By providing the focusing layer 230, the focal length can be adjusted without changing the curvature like a hemispherical microlens, and a shorter focal length can be implemented in a limited space. Here, the focal length may be inversely proportional to the thickness T of the focusing layer 230 . For example, as the thickness T of the focusing layer 230 increases, the focal length may become shorter, and as the thickness T of the focusing layer 230 decreases, the focal length may increase.

In order to effectively transmit the incident light focused through the pixel lens 240 to the photoelectric conversion device 220 , the focusing layer 230 may have a larger area than the pixel lens 240 . The focusing layer 230 may have a shape corresponding to each unit pixel 110 . Accordingly, the focusing layer 230 may contact each other between the adjacent unit pixels 110 . For example, the focusing layer 230 may have a rectangular shape.

In order to more effectively transmit the incident light focused through the pixel lens 240 to the photoelectric conversion device 220 , the focusing layer 230 may have a refractive index greater than that of the pixel lens 240 . As the focusing layer 230 , any light-transmitting material having a refractive index greater than that of the pixel lens 240 may be applied. Here, since the focusing layer 230 is located under the color filter layer 250 , various materials used in a typical semiconductor manufacturing process may be applied. For example, the light-transmitting material applicable to the focusing layer 230 may be an inorganic material, and silicon oxide, silicon nitride, titanium nitride, or the like may be used as the inorganic material. The focusing layer 230 may be a single layer or a multi-layer in which light-transmitting materials having different refractive indices are stacked. When the focusing layer 230 is multi-layered, the refractive index of the focusing layer 230 may have a slope, and the closer to the photoelectric conversion element 220 or the farther away from the pixel lens 240, the more the focusing layer 230 has. The refractive index may increase.

The pixel lens 240 may act as a light collecting member for condensing incident light. In order to improve the light collecting efficiency, the pixel lens 240 may be a multilayer in which two or more light collecting layers 241 and 242 are stacked, in which the upper layer 242 has a smaller area or line width than the lower layer 241 . Accordingly, the pixel lens 240 may have a multi-layered step shape. As the pixel lens 240 has a multi-layered step shape, the upper layer 242 and the lower layer 241 are based on the line widths W1 and W2 of the lower layer 241 exposed by the upper layer 242 or one sidewall of the lower layer 241 . ) between the line widths W1 and W2 may be smaller than the wavelength of the incident light. More specifically, the line widths W1 and W2 between the upper layer 242 and the lower layer 241 may be smaller than the wavelength of incident light that has passed through the color filter layer 250 and is color-separated. Through this, the pixel lens 240 having a multi-layered step shape can also collect light like a hemispherical lens. This is according to sub-wavelength optics. The line widths W1 and W2 between the upper layer 242 and the lower layer 241 may be the same (W1=W2) or different from each other (W1≠W2) depending on a reference sidewall.

The plurality of light collecting layers 241 and 242 may have the same shape as each other, and each of the plurality of light collecting layers 241 and 242 may be disposed parallel to each other. Specifically, the plurality of light collecting layers 241 and 242 may have a polygonal shape or a circular shape.

In order to further improve the light collecting efficiency, the thickness t2 of the upper layer 242 may be the same as the thickness t1 of the lower layer 241 (t1=t2), or may be thinner (t1>t2). In addition, in order to further improve the light collection efficiency, the refractive index of the upper layer 242 may be the same as or smaller than that of the lower layer 241 . The plurality of light collecting layers 241 and 242 may include a light-transmitting material. Here, when the upper layer 242 and the lower layer 241 have the same refractive index, they may be the same material. Since the plurality of light collecting layers 241 and 242 , that is, the pixel lens 240 is located under the color filter layer 250 , various materials used in a typical semiconductor manufacturing process may be applied. For example, the light transmitting material applicable to the plurality of light collecting layers 241 and 242 may be an inorganic material, and silicon oxide, silicon nitride, titanium nitride, or the like may be used as the inorganic material. In addition, each of the plurality of light collecting layers 241 and 242 may be a single layer or a multilayer in which light transmitting materials having different refractive indices are stacked. When the light collecting layer is a multi-layer, the refractive index of the light collecting layer may have a slope, and the refractive index of the light collecting layer may increase as it approaches the photoelectric conversion element 220 or the focusing layer 230 .

The color filter layer 250 is for color separation, is formed on the focusing layer 230 , covers the entire surface of the pixel lens 240 , and may have a flat surface. Here, since the color filter layer 250 has a shape that contacts the pixel lens 240 and covers the pixel lens 240 , light transmittance between the color filter layer 250 and the pixel lens 240 can be improved. That is, it is possible to improve the light collection efficiency. The color filter layer 250 may include at least one selected from the group consisting of a red filter, a green filter, a blue filter, a cyan filter, a yellow filter, a magenta filter, an infrared pass filter, an infrared cut filter, and a white filter. In order to further improve light collection efficiency, the color filter layer 250 may have a smaller refractive index than that of the pixel lens 240 .

The anti-reflection structures 260 and 270 are formed on the color filter layer 250 and include an anti-reflection layer 260 or a hemispherical lens 270 in which two or more material layers having different refractive indices are alternately stacked at least once. . The hemispherical lens 270 may perform a function of condensing incident light to the pixel lens 240 as well as an antireflection function of the incident light.

The image sensor having the above-described structure includes the pixel lens 240 having a multi-layered step shape, thereby improving light collection efficiency in the unit pixel 110 . In addition, since the color filter layer 250 has a shape that covers the pixel lens 240 , the light collection efficiency of the unit pixel 110 may be further improved. As such, as the light collection efficiency of the unit pixel 110 is improved, the quantum efficiency of the photoelectric conversion device 220 may also be improved. As a result, the performance of the image sensor can be improved.

Meanwhile, in the image sensor according to the embodiment, since the focusing layer and the pixel lens have a structure in which a plurality of material layers are stacked, an anti-reflection layer may be easily inserted between each layer. The anti-reflection layer prevents incident light from being reflected from the surface to prevent a decrease in light collection efficiency due to a decrease in the amount of light, but the formation position is limited in an image sensor having a hemispherical micro lens. Hereinafter, it 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 refer to multiple layers in which two or more material layers having different refractive indices are alternately stacked at least once.

4A to 4D are cross-sectional views illustrating formation positions of a focusing layer and an anti-reflection layer in a pixel lens according to an embodiment of the present invention.

First, as shown in FIG. 4A , a 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. In addition, a 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 by performing a deposition process before and after forming the focusing layer 230 , respectively.

Next, as shown in FIG. 4B , a third anti-reflection layer 283 may be formed on 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-reflection layer 283 may be formed by performing a deposition process to have a constant thickness along the surface of the structure after the pixel lens 240 is formed.

Next, as shown in FIG. 4C , a fourth anti-reflection layer 284 may be formed on the first light-collecting layer 241 , and a fifth anti-reflection layer 285 is formed on the second light-collecting layer 242 . can be formed. The fourth anti-reflection layer 284 and the fifth anti-reflection layer 285 may be formed together during the process of forming the first light collecting layer 241 and the second light collecting layer 242 , respectively. When the refractive indices of the first light collecting layer 241 and the second light collecting layer 242 are different from each other, the fourth anti-reflection layer 284 is a surface generated at the interface between the first light collecting layer 241 and the second light collecting layer 242 . reflection can be prevented.

Next, as shown in FIG. 4D , all of the first anti-reflection layer 281 to the fifth anti-reflection layer 285 may be formed.

As such, in the image sensor according to the embodiment, since the focusing layer 230 and the pixel lens 240 have a structure in which a plurality of material layers are stacked, an antireflection layer can be easily inserted between each layer. Through this, it is possible to further improve the light collection efficiency.

The image sensor according to the above-described embodiment may be used in various electronic devices or systems. Hereinafter, a case in which an image sensor according to an embodiment of the present invention is applied to a camera will be described with reference to FIG. 5 .

5 is a diagram schematically illustrating an electronic device having an image sensor according to an embodiment of the present invention.

Referring to FIG. 5 , an electronic device having an image sensor according to an embodiment may be a camera capable of capturing a still image or a moving image. The electronic device may include a driving unit 313 and a signal processing unit 312 that control/drive the optical system 310 , or an optical lens, a shutter unit 311 , an image sensor 300 and the shutter unit 311 . there is.

The optical system 310 guides image light (incident light) from the subject to the pixel array of the image sensor 300 (refer to reference numeral '100' in FIG. 1 ). The optical system 310 may include a plurality of optical lenses. The shutter unit 311 controls a light irradiation period and a shielding period for the image sensor 300 . The driving unit 313 controls a transmission operation of the image sensor 300 and a shutter operation of the shutter unit 311 . The signal processing unit 312 performs various types of signal processing on the signal output from the image sensor 300 . The image signal Dout after signal processing is stored in a storage medium such as a memory or output to a monitor or the like.

Although the technical idea of the present invention has been specifically described according to the above preferred embodiments, it should be noted that the above embodiments are for explanation only and not for limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

210: substrate 220: photoelectric conversion element
230: focusing layer 240: pixel lens
250: color filter layer 260, 270: anti-reflection structure

Claims (22)

a substrate including a photoelectric conversion element;
a pixel lens formed on the substrate and including a plurality of light collecting layers having a lower area larger than an upper layer;
a color filter layer covering the pixel lens; and
Anti-reflection structure formed on the color filter layer
including,
The refractive index of the upper layer is smaller than the refractive index of the lower layer, and the upper layer and the lower layer are formed of the same material,
In the pixel lens,
The line width of the lower layer exposed by the upper layer is smaller than the wavelength of the incident light.
◈Claim 2 was abandoned when paying the registration fee.◈ According to claim 1,
The image sensor further comprising a focusing layer interposed between the photoelectric conversion element and the pixel lens.
◈Claim 3 was abandoned when paying the registration fee.◈ 3. The method of claim 2,
The focusing layer has a refractive index greater than that of the pixel lens image sensor.
◈Claim 4 was abandoned when paying the registration fee.◈ 3. The method of claim 2,
and the focusing layer has a larger area than the pixel lens.
◈Claim 5 was abandoned when paying the registration fee.◈ 3. The method of claim 2,
A focal length between the pixel lens and the photoelectric conversion element is inversely proportional to a thickness of the focusing layer.
◈Claim 6 was abandoned when paying the registration fee.◈ The method of claim 1,
The pixel lens is an image sensor having a multi-layered step shape.
delete ◈Claim 8 was abandoned when paying the registration fee.◈ According to claim 1,
In the pixel lens,
A line width of the lower layer exposed by the upper layer is smaller than a wavelength of incident light that has passed through the color filter layer and is color-separated.
◈Claim 9 was abandoned at the time of payment of the registration fee.◈ According to claim 1,
In the pixel lens,
An image sensor in which each of the plurality of light collecting layers has the same shape and is disposed parallel to each other.
◈Claim 10 was abandoned when paying the registration fee.◈ According to claim 1,
In the pixel lens,
The thickness of the upper layer is equal to or thinner than the thickness of the lower layer.
delete ◈Claim 12 was abandoned when paying the registration fee.◈ According to claim 1,
The image sensor further comprising an anti-reflection layer formed on the pixel lens.
◈Claim 13 was abandoned when paying the registration fee.◈ According to claim 1,
and the color filter layer covers an entire surface of the pixel lens and has a flat surface.
◈Claim 14 was abandoned at the time of payment of the registration fee.◈ The method of claim 1,
The color filter layer has a smaller refractive index than the pixel lens image sensor.
◈Claim 15 was abandoned when paying the registration fee.◈ According to claim 1,
The anti-reflection structure,
and an anti-reflection layer formed on the color filter layer and alternately stacked at least once with two or more material layers having different refractive indices.
◈Claim 16 was abandoned when paying the registration fee.◈ According to claim 1,
The anti-reflection structure,
and a hemispherical lens formed on the color filter layer.
optical system;
an image sensor receiving light from the optical system and including a pixel array in which a plurality of unit pixels are arranged in a matrix structure; and
and a signal processing unit that performs a signal processing operation on the signal output from the image sensor,
Each of the plurality of unit pixels,
a substrate including a photoelectric conversion element;
a pixel lens formed on the substrate and including a plurality of light collecting layers having a lower area larger than an upper layer;
a color filter layer covering the pixel lens; and
Anti-reflection structure formed on the color filter layer
including,
The refractive index of the upper layer is smaller than the refractive index of the lower layer, and the upper layer and the lower layer are formed of the same material,
In the pixel lens,
The line width of the lower layer exposed by the upper layer is smaller than the wavelength of the incident light.
◈Claim 18 was abandoned when paying the registration fee.◈ 18. The method of claim 17,
The electronic device further comprising a focusing layer interposed between the photoelectric conversion element and the pixel lens.
◈Claim 19 was abandoned at the time of payment of the registration fee.◈ 19. The method of claim 18,
The focusing layer has a refractive index greater than that of the pixel lens,
The color filter layer has a refractive index smaller than that of the pixel lens.
◈Claim 20 was abandoned when paying the registration fee.◈ 19. The method of claim 18,
A focal length between the pixel lens and the photoelectric conversion element is inversely proportional to a thickness of the focusing layer.
delete ◈Claim 22 was abandoned when paying the registration fee.◈ 18. The method of claim 17,
The anti-reflection structure includes an anti-reflection layer or a hemispherical lens in which two or more material layers having different refractive indices are alternately stacked at least once.

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