JP2022075774A - Photodetection device and manufacturing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to improve sensitivity, while suppressing degradation of mixed color.

SOLUTION: A solid-state imaging apparatus includes: a semiconductor substrate which has a first surface for receiving incident light and a second surface directed to a side opposite to the first surface; a first trench and a second trench which are provided on the first surface of the semiconductor substrate; and a first recess and a second recess which are provided between the first trench and the second trench on the first surface of the semiconductor substrate and have a depth smaller than those of the first trench and the second trench. A first flat part of the semiconductor substrate is provided between the first trench and the first recess; a second flat part of the semiconductor substrate is provided between the second trench and the second recess; and a third flat part of the semiconductor substrate is provided between the first recess and the second recess and parallel to the first flat part and the second flat part in a cross sectional view. The present disclosed technology is applicable, for example, to a rear surface irradiation type solid-state imaging apparatus.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present disclosure relates to a photodetector and a method for manufacturing the same, and more particularly to a photodetector and a method for manufacturing the photodetector so as to be able to improve sensitivity while suppressing deterioration of color mixing.

In a solid-state image sensor, as a structure for preventing reflection of incident light, a so-called moth-eye structure has been proposed in which a minute uneven structure is provided at the interface on the light receiving surface side of the silicon layer on which the photodiode is formed (for example,). See Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 2010-272612 Japanese Unexamined Patent Publication No. 2013-33664

However, although the moth-eye structure can prevent the reflection of incident light and improve the sensitivity, the scattering is also large, and the amount of light leaking to the adjacent pixel is also large, so that the color mixing is deteriorated.

The present disclosure has been made in view of such a situation, and is intended to enable improvement of sensitivity while suppressing deterioration of color mixing.

The light detection device on the first side of the present disclosure includes a substrate, a first photoelectric conversion region provided on the substrate, and a second photoelectric conversion region adjacent to the first photoelectric conversion region and provided on the substrate. A trench provided between the region and the first photoelectric conversion region and the second photoelectric conversion region, which has a longer depth than the width, and above the first photoelectric conversion region. The first uneven structure provided on the light receiving surface side of the substrate, the second uneven structure provided on the light receiving surface side of the substrate above the second photoelectric conversion region, and at least a part of the inside of the trench. It has a first insulating film provided above the first uneven structure and the second concave-convex structure, and a light-shielding film provided above the first insulating film and above the trench. , The first insulating film contains hafnium oxide.

In the first aspect of the present disclosure, a first photoelectric conversion region is provided on the substrate, a second photoelectric conversion region is provided on the substrate next to the first photoelectric conversion region, and a first photoelectric conversion region and a second photoelectric conversion region are provided. A trench having a depth longer than the width is provided between the photoelectric conversion region, and a first uneven structure is provided on the light receiving surface side of the substrate above the first photoelectric conversion region. A second concavo-convex structure is provided on the light receiving surface side of the substrate above the two photoelectric conversion regions, and the first insulating film is provided above the first concavo-convex structure and the second concavo-convex structure, which is at least a part of the trench. A light-shielding film is provided above the one insulating film and above the trench, and the first insulating film contains hafnium oxide.

In the method of manufacturing the light detection device on the second side of the present disclosure, after forming an uneven structure on the surface of the substrate above the first photoelectric conversion region and the second photoelectric conversion region provided on the substrate, the first photoelectric conversion region is formed. The substrate between the conversion region and the second photoelectric conversion region is formed with a trench having a depth longer than the width length so as to be provided in at least a part of the trench. A first insulating film containing hafnium oxide is formed above the uneven structure, and a light-shielding film is formed above the first insulating film and above the trench. Alternatively, after forming a trench having a depth longer than a width length in the substrate between the first photoelectric conversion region and the second photoelectric conversion region provided on the substrate, the first photoelectric conversion region is formed. A first insulating film containing hafnium oxide is formed above the uneven structure so that an uneven structure is formed on the surface of the substrate above the conversion region and the second photoelectric conversion region and is provided in at least a part of the trench. And a light-shielding film is formed above the first insulating film and above the trench.

In the second aspect of the present disclosure, after the uneven structure is formed on the substrate surface above the first photoelectric conversion region and the second photoelectric conversion region provided on the substrate, the first photoelectric conversion region and the second photoelectric conversion region are formed. A trench having a depth length longer than a width length is formed on the substrate between the regions, or a substrate between the first photoelectric conversion region and the second photoelectric conversion region provided on the substrate. In addition, after a trench having a depth longer than a width is formed, an uneven structure is formed on the substrate surface above the first photoelectric conversion region and the second photoelectric conversion region. Then, a first insulating film containing hafnium oxide is formed above the uneven structure so as to be provided in at least a part of the trench, and a light-shielding film is formed above the first insulating film and above the trench. ..

The photodetector may be an independent device or a module incorporated into another device.

According to the first and second aspects of the present disclosure, it is possible to improve the sensitivity while suppressing the deterioration of color mixing.

It is a figure which shows the schematic structure of the solid-state image sensor which concerns on this disclosure. It is a figure which shows the cross-sectional composition example of the pixel which concerns on 1st Embodiment. It is a figure explaining the manufacturing method of a pixel. It is a figure explaining the manufacturing method of a pixel. It is a figure explaining other manufacturing method of a pixel. It is a figure explaining the effect of the pixel structure of this disclosure. It is a figure explaining the effect of the pixel structure of this disclosure. It is a figure which shows the cross-sectional composition example of the pixel which concerns on 2nd Embodiment. It is a figure explaining the manufacturing method of the pixel which concerns on 2nd Embodiment. It is a figure explaining the optimum condition of various parts of a pixel. It is a figure which shows the 1st variation of a pixel structure. It is a figure which shows the 2nd variation of a pixel structure. It is a figure which shows the 3rd variation of a pixel structure. It is a figure which shows the 4th variation of a pixel structure. It is a figure which shows the 5th variation of a pixel structure. It is a figure which shows the sixth variation of a pixel structure. It is a figure which shows the 7th variation of a pixel structure. It is a figure which shows the 8th variation of a pixel structure. It is a figure which shows the 9th variation of a pixel structure. It is a figure which shows the tenth variation of a pixel structure. It is a figure which shows the eleventh variation of a pixel structure. It is a figure which shows the twelfth variation of a pixel structure. It is a figure which shows the thirteenth variation of a pixel structure. It is a figure which shows the 14th variation of a pixel structure. It is a figure which shows the fifteenth variation of a pixel structure. It is a figure which shows the 16th variation of a pixel structure. It is a block diagram which shows the structural example of the image pickup apparatus as an electronic device which concerns on this disclosure.

Hereinafter, embodiments for carrying out the present disclosure (hereinafter referred to as embodiments) will be described. The explanation will be given in the following order.
1. 1. Schematic configuration example of a solid-state image sensor 2. Pixel structure according to the first embodiment (pixel structure having an antireflection portion and a light-shielding portion between pixels)
3. 3. Pixel structure according to the second embodiment (pixel structure in which a light-shielding portion between pixels is filled with metal)
4. Modification example of pixel structure 5. Application example to electronic devices

<1. Schematic configuration example of a solid-state image sensor>
FIG. 1 shows a schematic configuration of a solid-state image sensor according to the present disclosure.

The solid-state image sensor 1 of FIG. 1 has a pixel array unit 3 in which pixels 2 are arranged in a two-dimensional array on a semiconductor substrate 12 using, for example, silicon (Si) as a semiconductor, and a peripheral circuit unit around the pixel array unit 3. It is composed of. The peripheral circuit unit includes a vertical drive circuit 4, a column signal processing circuit 5, a horizontal drive circuit 6, an output circuit 7, a control circuit 8, and the like.

The pixel 2 includes a photodiode as a photoelectric conversion element and a plurality of pixel transistors. The plurality of pixel transistors are composed of four MOS transistors, for example, a transfer transistor, a selection transistor, a reset transistor, and an amplification transistor.

Further, the pixel 2 may have a shared pixel structure. This pixel sharing structure is composed of a plurality of photodiodes, a plurality of transfer transistors, one shared floating diffusion (floating diffusion region), and one shared other pixel transistor. That is, in the shared pixel, the photodiode and the transfer transistor constituting the plurality of unit pixels are configured by sharing the other pixel transistor.

The control circuit 8 receives an input clock and data instructing an operation mode and the like, and outputs data such as internal information of the solid-state image sensor 1. That is, the control circuit 8 generates a clock signal or a control signal that serves as a reference for the operation of the vertical drive circuit 4, the column signal processing circuit 5, the horizontal drive circuit 6, etc., based on the vertical synchronization signal, the horizontal synchronization signal, and the master clock. do. Then, the control circuit 8 outputs the generated clock signal and control signal to the vertical drive circuit 4, the column signal processing circuit 5, the horizontal drive circuit 6, and the like.

The vertical drive circuit 4 is composed of, for example, a shift register, selects a pixel drive wiring 10, supplies a pulse for driving the pixel 2 to the selected pixel drive wiring 10, and drives the pixel 2 in row units. That is, the vertical drive circuit 4 selectively scans each pixel 2 of the pixel array unit 3 in row units in the vertical direction, and a pixel signal based on the signal charge generated in the photoelectric conversion unit of each pixel 2 according to the amount of light received. Is supplied to the column signal processing circuit 5 through the vertical signal line 9.

The column signal processing circuit 5 is arranged for each column of the pixel 2, and performs signal processing such as noise removal for each pixel string of the signal output from the pixel 2 for one row. For example, the column signal processing circuit 5 performs signal processing such as CDS (Correlated Double Sampling) and AD conversion for removing fixed pattern noise peculiar to pixels.

The horizontal drive circuit 6 is composed of, for example, a shift register, and by sequentially outputting horizontal scanning pulses, each of the column signal processing circuits 5 is sequentially selected, and a pixel signal is output from each of the column signal processing circuits 5 as a horizontal signal line. Output to 11.

The output circuit 7 performs signal processing on the signals sequentially supplied from each of the column signal processing circuits 5 through the horizontal signal line 11 and outputs the signals. The output circuit 7 may, for example, perform only buffering, or may perform black level adjustment, column variation correction, various digital signal processing, and the like. The input / output terminal 13 exchanges signals with the outside.

The solid-state image sensor 1 configured as described above is a CMOS image sensor called a column AD method in which a column signal processing circuit 5 that performs CDS processing and AD conversion processing is arranged for each pixel string.

Further, the solid-state image sensor 1 is a back-illuminated MOS-type solid-state image sensor in which light is incident from the back surface side opposite to the front surface side of the semiconductor substrate 12 on which the pixel transistor is formed.

<2. Pixel structure according to the first embodiment>
<Example of pixel cross-section configuration>
FIG. 2 is a diagram showing a cross-sectional configuration example of the pixel 2 according to the first embodiment.

The solid-state image sensor 1 includes a semiconductor substrate 12, a multilayer wiring layer 21 formed on the surface side (lower side in the drawing) thereof, and a support substrate 22.

The semiconductor substrate 12 is made of, for example, silicon (Si), and is formed with a thickness of, for example, 1 to 6 μm. In the semiconductor substrate 12, for example, an N-type (second conductive type) semiconductor region 42 is formed for each pixel 2 in a P-type (first conductive type) semiconductor region 41, so that the photodiode PD is pixel-based. Is formed in. The P-type semiconductor region 41 facing both the front and back surfaces of the semiconductor substrate 12 also serves as a hole charge storage region for suppressing dark current.

At the pixel boundary of each pixel 2 between the N-type semiconductor regions 42, the P-type semiconductor region 41 is dug deep as shown in FIG. 2 in order to form the inter-pixel light-shielding portion 47 described later. It is included.

The interface (interface on the light receiving surface side) of the P-type semiconductor region 41 above the N-type semiconductor region 42, which is the charge storage region, has a so-called moth-eye structure that forms a fine uneven structure to prevent reflection of incident light. The antireflection unit 48 is configured. In the antireflection portion 48, the pitch of the spindle-shaped convex portion corresponding to the period of the unevenness is set to, for example, in the range of 40 nm to 200 nm.

The multilayer wiring layer 21 has a plurality of wiring layers 43 and an interlayer insulating film 44. Further, the multilayer wiring layer 21 is also formed with a plurality of pixel transistors Tr that read out the charges accumulated in the photodiode PD.

A pinning layer 45 is formed on the back surface side of the semiconductor substrate 12 so as to cover the upper surface of the P-type semiconductor region 41. The pinning layer 45 is formed by using a high dielectric having a negative fixed charge so that a positive charge (hole) storage region is formed at the interface with the semiconductor substrate 12 and the generation of dark current is suppressed. There is. By forming the pinning layer 45 so as to have a negative fixed charge, an electric field is applied to the interface with the semiconductor substrate 12 due to the negative fixed charge, so that a positive charge storage region is formed.

The pinning layer 45 is formed using, for example, hafnium oxide (HfO ₂ ). Further, the pinning layer 45 may be formed by using zirconium dioxide (ZrO ₂ ), tantalum oxide (Ta ₂ O ₅ ), or the like.

The transparent insulating film 46 is embedded in the dug portion of the P-type semiconductor region 41, and is formed on the entire back surface side of the upper portion of the pinning layer 45 of the semiconductor substrate 12. The dug portion of the P-type semiconductor region 41 in which the transparent insulating film 46 is embedded constitutes an inter-pixel light-shielding portion 47 that prevents leakage of incident light from adjacent pixels 2.

The transparent insulating film 46 is a material that transmits light and has an insulating property, and has a refractive index n1 smaller than the refractive index n2 of the semiconductor regions 41 and 42 (n1 <n2). Materials for the transparent insulating film 46 include silicon oxide (SiO ₂ ), silicon nitride (SiN), silicon oxynitride (SiON), hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), and zirconium oxide (ZrO ₂ ). ), Tantalum Oxide (Ta ₂ O ₅ ), Titanium Oxide (TIO ₂ ), Lantern Oxide (La ₂ O ₃ ), Placeodym Oxide (Pr ₂ O ₃ ), Cerium Oxide (CeO ₂ ), Neodim Oxide (Nd ₂ O ₃ ) ), Promethium oxide (Pm ₂ O ₃ ), Samalium oxide (Sm ₂ O ₃ ), Europium oxide (Eu ₂ O ₃ ), Gadrinium oxide (Gd ₂ O ₃ ), Terbium oxide (Tb ₂ O ₃ ), Disprosium oxide (Tb 2 O 3) Dy ₂ O ₃ ), formium oxide (Ho ₂ O ₃ ), thulium oxide (Tm ₂ O ₃ ), ytterbium oxide (Yb ₂ O ₃ ), lutetium oxide (Lu ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ) , Resin and the like can be used alone or in combination.

An antireflection film may be laminated on the upper side of the pinning layer 45 before the transparent insulating film 46 is formed. Materials for the antireflection film include silicon nitride (SiN), hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), tantalum oxide (Ta ₂ O ₅ ), and titanium oxide (TiO). ₂ ), lanthanum oxide (La ₂ O ₃ ), placeodym oxide (Pr ₂ O ₃ ), cerium oxide (CeO ₂ ), neodymium oxide (Nd ₂ O ₃ ), promethium oxide (Pm ₂ O ₃ ), samarium oxide (Sm) ₂ O ₃ ), Europium oxide (Eu ₂ O ₃ ), Gadrinium oxide (Gd ₂ O ₃ ), Terbium oxide (Tb ₂ O ₃ ), Disprosium oxide (Dy ₂ O ₃ ), Formium oxide (Ho ₂ O ₃ ), Thulium oxide (Tm ₂ O ₃ ), ytterbium oxide (Yb ₂ O ₃ ), lutetium oxide (Lu ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ) and the like can be used.

The antireflection film may be formed only on the upper surface of the antireflection portion 48 having a moth-eye structure, or may be formed on both the upper surface of the antireflection portion 48 and the side surface of the interpixel light-shielding portion 47 as in the pinning layer 45. It may be a film.

A light-shielding film 49 is formed in the pixel boundary region on the transparent insulating film 46. The material of the light-shielding film 49 may be any material that shields light, and for example, tungsten (W), aluminum (Al), copper (Cu), or the like can be used.

A flattening film 50 is formed on the entire upper surface of the transparent insulating film 46 including the light-shielding film 49. As the material of the flattening film 50, for example, an organic material such as a resin can be used.

A red (red), green (green), or blue (blue) color filter layer 51 is formed on the upper side of the flattening film 50 for each pixel. The color filter layer 51 is formed by rotationally applying a photosensitive resin containing a dye such as a pigment or a dye, for example. Each color of Red, Green, and Blue is arranged by, for example, a bayer arrangement, but may be arranged by another arrangement method. In the example of FIG. 2, a blue (B) color filter layer 51 is formed in the pixel 2 on the right side, and a green (G) color filter layer 51 is formed in the pixel 2 on the left side.

An on-chip lens 52 is formed for each pixel 2 on the upper side of the color filter layer 51. The on-chip lens 52 is formed of, for example, a resin-based material such as a styrene-based resin, an acrylic-based resin, a styrene-acrylic copolymer resin, or a siloxane-based resin. In the on-chip lens 52, the incident light is condensed, and the condensed light is efficiently incident on the photodiode PD via the color filter layer 51.

Each pixel 2 of the pixel array unit 3 of the solid-state image sensor 1 is configured as described above.

<Pixel manufacturing method according to the first embodiment>
Next, a method of manufacturing the pixel 2 according to the first embodiment will be described with reference to FIGS. 3 and 4.

First, as shown in FIG. 3A, the photoresist 81 is applied to the upper surface of the P-shaped semiconductor region 41 on the back surface side of the semiconductor substrate 12, and the portion that becomes the recess of the moth-eye structure of the antireflection portion 48 by the lithography technique. The photoresist 81 is patterned so as to open.

Then, by performing a dry etching process on the semiconductor substrate 12 based on the pattern-processed photoresist 81, as shown in FIG. 3B, a recess of the moth-eye structure of the antireflection portion 48 is formed, and then a recess of the moth-eye structure is formed. The photoresist 81 is removed. The moth-eye structure of the antireflection portion 48 can also be formed by a wet etching process instead of a dry etching process.

Next, as shown in FIG. 3C, the photoresist 82 is applied to the upper surface of the P-type semiconductor region 41 on the back surface side of the semiconductor substrate 12, and the dug portion of the interpixel shading portion 47 is opened by the lithography technique. The photoresist 82 is patterned as described above.

Then, by performing an anisotropic dry etching process on the semiconductor substrate 12 based on the pattern-processed photoresist 82, a trench structure of the interpixel light-shielding portion 47 is formed as shown in FIG. 3D. After that, the photoresist 82 is removed. As a result, the inter-pixel light-shielding portion 47 having a trench structure is formed.

The inter-pixel light-shielding portion 47, which needs to be dug deep into the semiconductor substrate 12, is formed by anisotropic etching. As a result, the inter-pixel light-shielding portion 47 can be formed into a digging shape without a taper, and a waveguide function is generated.

Next, as shown in FIG. 4A, the entire surface of the semiconductor substrate 12 on which the antireflection portion 48 having a moth-eye structure and the interpixel shading portion 47 having a trench structure are formed is pinned by, for example, a CVD (Chemical Vapor Deposition) method. The layer 45 is formed.

Next, as shown in FIG. 4B, a transparent insulating film 46 is formed on the upper surface of the pinning layer 45 by using a highly implantable film forming method such as a CVD method or a filling material. As a result, the transparent insulating film 46 is also filled inside the dug-in interpixel light-shielding portion 47.

Then, as shown in FIG. 4C, after the light-shielding film 49 is formed only in the region between the pixels by the lithography technique, as shown in FIG. 4D, the flattening film 50, the color filter layer 51, and the on-chip The lens 52 is formed in that order.

The solid-state image sensor 1 having the structure of FIG. 2 can be manufactured as described above.

<Other manufacturing methods of pixels according to the first embodiment>
In the manufacturing method described above, first, the antireflection portion 48 having a moth-eye structure was formed, and then the interpixel light-shielding portion 47 having a trench structure was formed. However, the order in which the antireflection portion 48 and the inter-pixel shading portion 47 are formed may be reversed.

Therefore, with reference to FIG. 5, a manufacturing method will be described in which the interpixel light-shielding portion 47 having a trench structure is first formed and then the antireflection portion 48 having a moth-eye structure is formed.

First, as shown in FIG. 5A, the photoresist 91 is applied to the upper surface of the P-type semiconductor region 41 on the back surface side of the semiconductor substrate 12, and the trench portion of the interpixel shading portion 47 is opened by the lithography technique. The photoresist 91 is patterned.

Then, by performing an anisotropic dry etching process on the semiconductor substrate 12 based on the pattern-processed photoresist 91, a trench portion of the inter-pixel light-shielding portion 47 is formed as shown in FIG. 5B. After that, the photoresist 91 is removed. As a result, the inter-pixel light-shielding portion 47 having a trench structure is formed.

Next, as shown in FIG. 5C, the photoresist 92 is applied to the upper surface of the P-type semiconductor region 41, and the photoresist 92 is used to open the concave portion of the moth-eye structure of the antireflection portion 48 by the lithography technique. 92 is patterned.

Then, by performing a dry etching process on the semiconductor substrate 12 based on the pattern-processed photoresist 92, as shown in FIG. 5D, after the recess of the moth-eye structure of the antireflection portion 48 is formed, the recess is formed. The photoresist 92 is removed. As a result, the antireflection portion 48 having a moth-eye structure is formed. The moth-eye structure of the antireflection portion 48 can also be formed by a wet etching process instead of a dry etching process.

The state shown in FIG. 5D is the same as the state shown in FIG. 3D. Therefore, the subsequent manufacturing methods of the transparent insulating film 46, the flattening film 50, and the like are the same as those in FIG. 4 described above, and thus the description thereof will be omitted.

<Effect of pixel structure according to the first embodiment>
FIG. 6 is a diagram illustrating the effect of the pixel structure of the pixel 2 shown in FIG.

FIG. 6A is a diagram illustrating the effect of the antireflection portion 48 of the moth-eye structure.

Since the antireflection portion 48 has a moth-eye structure, reflection of incident light is prevented. Thereby, the sensitivity of the solid-state image sensor 1 can be improved.

FIG. 6B is a diagram illustrating the effect of the inter-pixel light-shielding portion 47 having a trench structure.

Conventionally, when the inter-pixel light-shielding portion 47 is not provided, the incident light scattered by the antireflection portion 48 may penetrate the photoelectric conversion regions (semiconductor regions 41 and 42). The inter-pixel shading unit 47 has the effect of reflecting the incident light scattered by the antireflection unit 48 of the moth-eye structure and confining the incident light in the photoelectric conversion region. As a result, the optical distance for absorbing silicon is extended, so that the sensitivity can be improved.

Assuming that the refractive index of the interpixel light-shielding portion 47 is n1 = 1.5 (corresponding to SiO ₂ ) and the refractive index of the semiconductor region 41 in which the photoelectric conversion region is formed is n2 = 4.0, it is derived by the difference in refractive index (n1 <n2). Since the waveguide effect (photoelectric conversion region: core, interpixel shading portion 47: cladding) is generated, the incident light is confined in the photoelectric conversion region. The moth-eye structure has a demerit that the color mixing is deteriorated by light scattering, but the deterioration of the color mixing can be canceled by combining with the inter-pixel light-shielding unit 47, and further, the incident angle advancing in the photoelectric conversion region is increased, so that the photoelectric is photoelectric. Generates the merit of improving conversion efficiency.

FIG. 7 is a diagram showing the effect of the pixel structure of the pixel 2 of the present disclosure in comparison with other structures.

Each of FIGS. 7A to 7D has an upper and lower two-stage configuration, the upper figure shows a cross-sectional structure diagram of a pixel, and the lower figure shows a green parallel light to a pixel having a pixel structure in the upper stage. It is a distribution diagram which shows the light intensity in the semiconductor substrate 12 when it is made incident. For ease of understanding, in FIGS. 7A to 7D, the parts corresponding to the structure of the pixel 2 in FIG. 2 are designated by the same reference numerals.

The upper part of FIG. 7A shows the pixel structure of a general solid-state image sensor, and has neither the antireflection portion 48 of the moth-eye structure nor the inter-pixel shading portion 47 due to the trench structure, and the pinning layer 45A is a P-type semiconductor region. The pixel structure formed flat on 41 is shown.

In the distribution map showing the light intensity shown in the lower part of FIG. 7A, the stronger the light intensity is, the darker the density is. Assuming that the light receiving sensitivity of the Green pixel is the reference (1.0), a small amount of Green light passes through the Blue pixel, so the light receiving sensitivity of the Blue pixel in FIG. 7A is 0.06, and the total light receiving sensitivity of the two pixels is 1.06. ..

The upper part of FIG. 7B shows a pixel structure in which only the antireflection portion 48 of the moth-eye structure is formed on the P-type semiconductor region 41.

Looking at the light intensity distribution map shown in the lower part of FIG. 7B, the incident light scattered by the antireflection portion 48 of the moth-eye structure leaks into the adjacent Blue pixel. Therefore, the light receiving sensitivity of the Green pixel is reduced to 0.90, while the light receiving sensitivity of the adjacent Blue pixel is increased to 0.16. The total light receiving sensitivity of the two pixels is 1.06.

FIG. 7C shows a pixel structure in which only the inter-pixel light-shielding portion 47 having a trench structure is formed in the P-type semiconductor region 41.

Looking at the distribution diagram of the light intensity shown in the lower part of FIG. 7C, the light intensity of the Green pixel is 1.01 and the light receiving sensitivity of the Blue pixel is 0.06, which is almost the same as the pixel structure of FIG. 7A. , 1.07.

FIG. 7D shows the pixel structure of the present disclosure shown in FIG.

Looking at the light intensity distribution map shown in the lower part of FIG. 7D, the blue pixel next to the incident light scattered by the antireflection portion 48 of the moth-eye structure is prevented from being reflected upward by the antireflection portion 48 of the moth-eye structure. The leakage to the pixel is prevented by the inter-pixel light-shielding portion 47. As a result, the light receiving sensitivity of the Green pixel has increased to 1.11 and the light receiving sensitivity of the Blue pixel is 0.07, which is the same level as the pixel structure of FIG. 7C. The total light receiving sensitivity of the two pixels is 1.18.

As described above, according to the pixel structure of the present disclosure shown in FIG. 2, the antireflection portion 48 of the moth-eye structure prevents the reflection from the upper side, and the inter-pixel light-shielding portion 47 scatters by the antireflection portion 48. It is possible to prevent the incident light from leaking to the adjacent pixel. Therefore, it is possible to improve the sensitivity while suppressing the deterioration of color mixing.

<3. Pixel structure according to the second embodiment>
<Example of pixel cross-section configuration>
FIG. 8 is a diagram showing a cross-sectional configuration example of the pixel 2 according to the second embodiment.

In FIG. 8, the parts corresponding to the first embodiment shown in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

In the second embodiment shown in FIG. 8, a metal material such as tungsten (W) is filled in the central portion of the inter-pixel light-shielding portion 47 of the trench structure arranged between the pixels 2. The point that the metal light-shielding portion 101 is newly provided is different from the first embodiment described above.

Further, in the second embodiment, the transparent insulating film 46 laminated on the surface of the pinning layer 45 is conformally formed by using, for example, a sputtering method.

In the solid-state image sensor 1 of the second embodiment, the color mixing can be further suppressed by further providing the metal light-shielding portion 101.

<Pixel manufacturing method according to the second embodiment>
A method of manufacturing the pixel 2 according to the second embodiment will be described with reference to FIG. 9.

The state shown in FIG. 9A is the same as the state of FIG. 4A described in the pixel manufacturing method according to the first embodiment. Therefore, the manufacturing method until the pinning layer 45 is formed is the same as that of the first embodiment described above.

Then, as shown in FIG. 9B, a transparent insulating film 46 is conformally formed on the upper surface of the pinning layer 45, for example, by a sputtering method.

Next, as shown in FIG. 9C, the metal light-shielding portion 101 and the light-shielding film 49 are simultaneously formed by pattern processing only the region between the pixels by, for example, tungsten (W) or the like by a lithography technique. .. Of course, the metal light-shielding portion 101 and the light-shielding film 49 may be formed separately by using different metal materials.

After that, as shown in FIG. 9D, the flattening film 50, the color filter layer 51, and the on-chip lens 52 are formed in that order.

<Example of optimum conditions for pixel structure>
With reference to FIG. 10, the optimum conditions at various points of the pixel 2 will be described.

(Moss eye arrangement area L1 of antireflection unit 48)
In the above-described embodiment, the antireflection portion 48 having a moth-eye structure is formed in the entire region on the light receiving surface side of the semiconductor regions 41 and 42 in which the photodiode PD is formed. However, as shown in FIG. 10, the moth-eye arrangement region L1 (moth-eye arrangement width L1) of the antireflection portion 48 is formed only in the pixel center portion in a region of a predetermined ratio with respect to the pixel region L4 (pixel width L4). can do. It is desirable that the moth-eye arrangement region L1 of the antireflection portion 48 is a region that is approximately 80% of the pixel region L4.

Condensing by the on-chip lens 52 is focused on the center of the sensor (photodiode PD), which is a photoelectric conversion region. Therefore, the closer to the center of the sensor, the stronger the light intensity, and the farther away from the center of the sensor, the weaker the light intensity. In the region far from the center of the sensor, there are many diffracted light noise components, that is, color mixing noise components to adjacent pixels. Therefore, by not forming a moth-eye structure in the vicinity of the inter-pixel light-shielding portion 47, light scattering can be suppressed and noise can be suppressed. The moth-eye arrangement region L1 of the antireflection portion 48 varies depending on the difference in the upper layer structure such as the pixel size, the on-chip lens curvature, and the total thickness of the pixels 2, but the on-chip lens 52 usually has the center 8 of the sensor region. Since the spot is focused on the split area, it is desirable that the area is approximately 80% of the pixel area L4.

Further, the size of the convex portion (spindle shape) of the moth-eye structure can be formed to be different for each color. As the size of the convex portion, the height, the arrangement area (the area where the convex portion is formed in a plan view), and the pitch can be defined.

The height of the convex portion is lowered as the wavelength of the incident light is shorter. That is, if the height of the convex portion of the red pixel 2 is h _R , the height of the convex portion of the green pixel 2 is h _G , and the height of the convex portion of the blue pixel 2 is h _B , then h _R > h. It can be formed so that the magnitude relationship of _G > h _B is established.

Further, the arrangement area of the convex portion is reduced as the wavelength of the incident light is shorter. That is, assuming that the arrangement area of the convex portion of the Red pixel 2 is x _R , the arrangement area of the convex portion of the Green pixel 2 is x _G , and the arrangement area of the convex portion of the Blue pixel 2 is x _B , x _R > x. It can be formed so that the magnitude relationship of _G > x _B is established. The width of the arrangement area in one direction corresponds to the moth-eye arrangement width L1 in FIG.

The pitch of the convex portion is lowered as the wavelength of the incident light is shorter. That is, if the pitch of the convex portion of the red pixel 2 is p _R , the pitch height of the green pixel 2 is p _G , and the pitch of the convex portion of the blue pixel 2 is p _B , then p _R > p _G > p. It can be formed so that the magnitude relationship of _B is established.

(Groove width L2 of the inter-pixel shading portion 47)
The groove width L2 of the inter-pixel light-shielding portion 47, which is necessary for preventing leakage of incident light to adjacent pixels and for total internal reflection, will be examined.

The groove width L2 of the inter-pixel light-shielding portion 47 has a wavelength λ of incident light λ = 600 nm, a refractive index n2 of the semiconductor region 41 of 4.0, a refractive index n1 of the inter-pixel light-shielding portion 47 of 1.5 (corresponding to SiO ₂ ), and the semiconductor region 41. Assuming that the angle of incidence on the inter-pixel light-shielding portion 47 is θ = 60 °, it may be 40 nm or more. However, from the viewpoint of the margin satisfying the optical characteristics and the process embedding property, it is desirable that the groove width L2 of the inter-pixel light-shielding portion 47 is 200 nm or more.

(Digging amount L3 of the inter-pixel shading portion 47)
The digging amount L3 of the inter-pixel light-shielding portion 47 will be examined.

The larger the digging amount L3 of the inter-pixel light-shielding portion 47, the higher the effect of suppressing color mixing. However, when the amount of digging exceeds a certain level, the degree of color mixing suppression becomes saturated. Further, the focal position and the scattering intensity depend on the incident light wavelength. Specifically, when the wavelength is short, the focal position is high and the scattering intensity is strong, so that the color mixing in the shallow region is large, and the amount of digging may be small. On the other hand, when the wavelength is long, the focal position is low and the scattering intensity is weak, so that the color mixing in the deep region is large, and the amount of digging is desired to be large. From the above, it is desirable that the digging amount L3 of the inter-pixel light-shielding portion 47 is equal to or larger than the incident light wavelength. For example, it is desirable that the digging amount L3 of the blue pixel 2 is 450 nm or more, the digging amount L3 of the green pixel 2 is 550 nm or more, and the digging amount L3 of the red pixel 2 is 650 nm or more.

In the above description, the inter-pixel light-shielding portion 47 is formed into a digging shape without taper by using an anisotropic dry etching process in order to maximize the waveguide function and not reduce the sensor area. I decided.

However, if the inter-pixel light-shielding portion 47 and the N-type semiconductor region 42 are sufficiently separated from each other and the inter-pixel light-shielding portion 47 is formed in a tapered shape without affecting the area of the photodiode PD, the inter-pixel light-shielding portion 47 is light-shielded. The shape of the portion 47 may be a tapered shape. For example, if the refractive index n1 = 1.5 (corresponding to SiO ₂ ) of the inter-pixel light-shielding portion 47 and the refractive index n2 = 4.0 of the P-type semiconductor region 41, the interfacial reflectance is extremely high, so the shape of the inter-pixel light-shielding portion 47 is changed. , Can be forward-tapered or reverse-tapered within the range of 0 to 30 °.

<4. Deformation example of pixel structure>
A plurality of variations of the pixel structure will be described with reference to FIGS. 11 to 26. 11 to 26 are described by using a pixel structure shown in a simplified manner as compared with the cross-sectional configuration example as shown in FIGS. 2 and 8, and different reference numerals are given even for the corresponding components. Some are attached.

FIG. 11 is a diagram showing a first variation of the pixel structure.

First, with reference to FIG. 11, a basic configuration common to each variation of the pixel structure described below will be described.

As shown in FIG. 11, in the solid-state image sensor 1, the antireflection film 111, the transparent insulating film 46, and the color filter are formed on the semiconductor substrate 12 in which the N-type semiconductor region 42 constituting the photodiode PD is formed for each pixel 2. The layer 51 and the on-chip lens 52 are laminated and configured.

The antireflection film 111 has, for example, a laminated structure in which a fixed charge film and an oxide film are laminated, and for example, an insulating thin film having a high dielectric constant (High-k) by an ALD (Atomic Layer. Deposition) method can be used. .. Specifically, hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TIO ₂ ), STO (Strontium Titan Oxide) and the like can be used. In the example of FIG. 11, the antireflection film 111 is configured by laminating a hafnium oxide film 112, an aluminum oxide film 113, and a silicon oxide film 114.

Further, a light-shielding film 49 is formed between the pixels 2 so as to be laminated on the antireflection film 111. As the light-shielding film 49, a single-layer metal film such as titanium (Ti), titanium nitride (TiN), tungsten (W), aluminum (Al), or tungsten nitride (WN) is used. Alternatively, as the light-shielding film 49, a laminated film of these metals (for example, a laminated film of titanium and tungsten, a laminated film of titanium nitride and tungsten, etc.) may be used.

In the solid-state image sensor 1 configured as described above, in the first variation of the pixel structure, a region having a predetermined width that does not form the antireflection portion 48 is provided between the pixels 2 at the interface on the light receiving surface side of the semiconductor substrate 12. The flat portion 53 is provided by the above. As described above, the antireflection portion 48 is provided by forming a moth-eye structure (fine uneven structure), and the moth-eye structure is not formed in the region between the pixels 2 and leaves a flat surface. Provides a flat portion 53. In this way, by adopting the pixel structure in which the flat portion 53 is provided, the generation of diffracted light in the region having a predetermined width (pixel separation region) in the vicinity of the other adjacent pixels 2 is suppressed, and the generation of color mixing is prevented. be able to.

That is, when the moth-eye structure is formed on the semiconductor substrate 12, diffraction of vertically incident light occurs. For example, as the pitch of the moth-eye structure increases, the component of the diffracted light increases, and the other pixels 2 adjacent to the semiconductor substrate 2 have a diffracted light component. It is known that the proportion of incident light increases.

On the other hand, in the solid-state image sensor 1, by providing the flat portion 53 in a region having a predetermined width between the pixels 2 where the diffracted light easily leaks to other adjacent pixels 2, the flat portion 53 receives the vertically incident light. Since diffraction does not occur, it is possible to prevent the occurrence of color mixing.

FIG. 12 is a diagram showing a second variation of the pixel structure.

In FIG. 12, the basic configuration of the solid-state image sensor 1 is the same as the configuration shown in FIG.
Then, in the second variation of the pixel structure, the pixel separation portion 54 that separates the pixels 2 from each other is formed on the semiconductor substrate 12.

When the pixel separation unit 54 digs a trench between the N-type semiconductor regions 42 constituting the photodiode PD, forms an aluminum oxide film 113 on the inner surface of the trench, and further forms a silicon oxide film 114. It is formed by embedding an insulator 55 in a trench.

By constructing such a pixel separation unit 54, the adjacent pixels 2 are electrically separated from each other by the insulator 55 embedded in the trench. As a result, it is possible to prevent the electric charge generated inside the semiconductor substrate 12 from leaking to the adjacent pixels 2.

Further, also in the second variation of the pixel structure, by adopting the pixel structure in which the flat portion 53 is provided, it is possible to suppress the generation of diffracted light in the pixel separation region and prevent the generation of color mixing.

FIG. 13 is a diagram showing a third variation of the pixel structure.

In FIG. 13, the basic configuration of the solid-state image sensor 1 is the same as the configuration shown in FIG.
Then, in the third variation of the pixel structure, the pixel separation portion 54A that separates the pixels 2 from each other is formed on the semiconductor substrate 12.

When the pixel separation unit 54A digs a trench between the N-type semiconductor regions 42 constituting the photodiode PD, forms an aluminum oxide film 113 on the inner surface of the trench, and forms a silicon oxide film 114. The insulating material 55 is embedded in the trench, and the light-shielding material 56 is embedded when the light-shielding film 49 is formed inside the insulating material 55. The light-shielding object 56 is formed of a light-shielding metal so as to be integrated with the light-shielding film 49.

By constructing such a pixel separation unit 54A, the adjacent pixels 2 are electrically separated by the insulator 55 embedded in the trench and optically separated by the light-shielding object 56. As a result, it is possible to prevent the electric charge generated inside the semiconductor substrate 12 from leaking to the adjacent pixels 2, and it is possible to prevent the light from the oblique direction from leaking to the adjacent pixels 2.

Further, also in the third variation of the pixel structure, by adopting the pixel structure in which the flat portion 53 is provided, it is possible to suppress the generation of diffracted light in the pixel separation region and prevent the generation of color mixing.

FIG. 14 is a diagram showing a fourth variation of the pixel structure.

In FIG. 14, the basic configuration of the solid-state image sensor 1 is the same as the configuration shown in FIG.
Then, in the fourth variation of the pixel structure, the pixel separation portion 54B that separates the pixels 2 from each other is formed on the semiconductor substrate 12.

When the pixel separation unit 54B digs a trench between the N-type semiconductor regions 42 constituting the photodiode PD, forms an aluminum oxide film 113 on the inner surface of the trench, and forms a silicon oxide film 114. The insulating material 55 is embedded in the trench, and the light-shielding material 56 is further embedded in the trench. The pixel separation unit 54B is configured such that the light-shielding film 49 is not provided on the flat portion 53.

By constructing such a pixel separation unit 54B, the adjacent pixels 2 are electrically separated by the insulator 55 embedded in the trench and optically separated by the light-shielding object 56. As a result, it is possible to prevent the electric charge generated inside the semiconductor substrate 12 from leaking to the adjacent pixels 2, and it is possible to prevent the light from the oblique direction from leaking to the adjacent pixels 2.

Further, also in the fourth variation of the pixel structure, by adopting the pixel structure in which the flat portion 53 is provided, it is possible to suppress the generation of diffracted light in the pixel separation region and prevent the generation of color mixing.

FIG. 15 is a diagram showing a fifth variation of the pixel structure.

In FIG. 15, the basic configuration of the solid-state image sensor 1 is the same as the configuration shown in FIG.
In the fifth variation of the pixel structure, the shape of the antireflection portion 48A is formed so that the depth of the unevenness constituting the moth-eye structure becomes shallow in the vicinity of the periphery of the pixel 2.

That is, as shown in FIG. 15, the antireflection unit 48A is, for example, in the peripheral portion of the pixel 2, that is, in the vicinity of the other adjacent pixels 2 as compared with the antireflection unit 48 shown in FIG. In the portion, the depth of the unevenness constituting the moth-eye structure is formed shallow.

By forming the depth of the uneven structure in the peripheral portion of the pixel 2 to be shallow in this way, it is possible to suppress the generation of diffracted light in the peripheral portion thereof. Further, also in the fifth variation of the pixel structure, by adopting the pixel structure in which the flat portion 53 is provided, it is possible to suppress the generation of diffracted light in the pixel separation region and further prevent the generation of color mixing.

FIG. 16 is a diagram showing a sixth variation of the pixel structure.

In FIG. 16, the basic configuration of the solid-state image sensor 1 is the same as the configuration shown in FIG.
In the sixth variation of the pixel structure, the shape of the antireflection portion 48A is formed so that the depth of the unevenness constituting the moth-eye structure becomes shallow in the peripheral portion of the pixel 2, and the pixel separation portion 54 is formed. It is formed.

By forming such an antireflection portion 48A, it is possible to suppress the generation of diffracted light in the peripheral portion of the pixel 2, and the pixel separation portion 54 electrically separates the adjacent pixels 2 from each other. Can be done. Further, also in the sixth variation of the pixel structure, by adopting the pixel structure provided with the flat portion 53, it is possible to suppress the generation of diffracted light in the pixel separation region and further prevent the generation of color mixing.

FIG. 17 is a diagram showing a seventh variation of the pixel structure.

In FIG. 17, the basic configuration of the solid-state image sensor 1 is the same as the configuration shown in FIG.
In the seventh variation of the pixel structure, the shape of the antireflection portion 48A is formed so that the depth of the unevenness constituting the moth-eye structure becomes shallow in the vicinity of the periphery of the pixel 2, and the pixel separation portion 54A is formed. It is formed.

By forming such an antireflection portion 48A, it is possible to suppress the generation of diffracted light in the peripheral portion of the pixel 2, and the pixel separation portion 54A electrically and optically connect the adjacent pixels 2 to each other. Can be separated. Further, even in the seventh variation of the pixel structure, by adopting the pixel structure provided with the flat portion 53, it is possible to suppress the generation of diffracted light in the pixel separation region and further prevent the generation of color mixing.

FIG. 18 is a diagram showing an eighth variation of the pixel structure.

In FIG. 18, the basic configuration of the solid-state image sensor 1 is the same as the configuration shown in FIG.
In the eighth variation of the pixel structure, the shape of the antireflection portion 48A is formed so that the depth of the unevenness constituting the moth-eye structure becomes shallow in the vicinity of the periphery of the pixel 2, and the pixel separation portion 54B is formed. It is formed.

By forming such an antireflection portion 48A, it is possible to suppress the generation of diffracted light in the peripheral portion of the pixel 2, and the pixel separation portion 54B electrically and optically connect the adjacent pixels 2 to each other. Can be separated. Further, also in the eighth variation of the pixel structure, by adopting the pixel structure provided with the flat portion 53, it is possible to suppress the generation of diffracted light in the pixel separation region and further prevent the generation of color mixing.

FIG. 19 is a diagram showing a ninth variation of the pixel structure.

In FIG. 19, the basic configuration of the solid-state image sensor 1 is the same as the configuration shown in FIG.
Then, in the ninth variation of the pixel structure, the antireflection portion 48B is formed in a region narrower than, for example, the antireflection portion 48 in FIG.

That is, as shown in FIG. 19, the antireflection unit 48B is, for example, in the peripheral portion of the pixel 2, that is, in the vicinity of the other adjacent pixels 2 as compared with the antireflection unit 48 shown in FIG. In the portion, the area forming the moth-eye structure is reduced. As a result, the flat portion 53A is formed wider than the flat portion 53 in FIG.

As described above, by providing the flat portion 53A widely without forming the moth-eye structure in the peripheral portion of the pixel 2, it is possible to suppress the generation of diffracted light in the peripheral portion thereof. As a result, even in the ninth variation of the pixel structure, it is possible to suppress the generation of diffracted light in the pixel separation region and further prevent the generation of color mixing.

FIG. 20 is a diagram showing a tenth variation of the pixel structure.

In FIG. 20, the basic configuration of the solid-state image sensor 1 is the same as the configuration shown in FIG.
In the tenth variation of the pixel structure, the region where the antireflection portion 48B is formed is narrowed, and the pixel separation portion 54 is formed.

By forming such an antireflection portion 48B, it is possible to suppress the generation of diffracted light in the peripheral portion of the pixel 2, and the pixel separation portion 54 electrically separates the adjacent pixels 2 from each other. Can be done. Further, even in the tenth variation of the pixel structure, by adopting the pixel structure in which the flat portion 53A is widely provided, it is possible to suppress the generation of diffracted light in the pixel separation region and further prevent the generation of color mixing.

FIG. 21 is a diagram showing an eleventh variation of the pixel structure.

In FIG. 21, the basic configuration of the solid-state image sensor 1 is the same as the configuration shown in FIG.
In the eleventh variation of the pixel structure, the region where the antireflection portion 48B is formed is narrowed, and the pixel separation portion 54A is formed.

By forming such an antireflection portion 48B, it is possible to suppress the generation of diffracted light in the peripheral portion of the pixel 2, and the pixel separation portion 54A electrically and optically connect the adjacent pixels 2 to each other. Can be separated. Further, even in the 21st variation of the pixel structure, by adopting the pixel structure in which the flat portion 53A is widely provided, it is possible to suppress the generation of diffracted light in the pixel separation region and further prevent the generation of color mixing.

FIG. 22 is a diagram showing a twelfth variation of the pixel structure.

In FIG. 22, the basic configuration of the solid-state image sensor 1 is the same as the configuration shown in FIG.
In the twelfth variation of the pixel structure, the region where the antireflection portion 48B is formed is narrowed, and the pixel separation portion 54B is formed.

By forming such an antireflection portion 48B, it is possible to suppress the generation of diffracted light in the peripheral portion of the pixel 2, and the pixel separation portion 54B electrically and optically connect the adjacent pixels 2 to each other. Can be separated. Further, even in the 21st variation of the pixel structure, by adopting the pixel structure in which the flat portion 53A is widely provided, it is possible to suppress the generation of diffracted light in the pixel separation region and further prevent the generation of color mixing.

FIG. 23 is a diagram showing a thirteenth variation of the pixel structure.

In FIG. 23, the basic configuration of the solid-state image sensor 1 is the same as the configuration shown in FIG.
In the thirteenth variation of the pixel structure, the phase difference pixel 2A used for the image plane phase difference AF (Auto Focus) is provided, and the phase difference pixel 2A is provided with the antireflection unit 48. Is not provided. The phase difference pixel 2A outputs a signal used for autofocus control using the phase difference on the image plane, and the light receiving surface side interface is formed on a flat surface by not providing the antireflection portion 48. ..

As shown in FIG. 23, in the phase difference pixel 2A used for the image plane phase difference AF, a light shielding film 49A is formed so as to shield substantially half of the opening. For example, a pair of a phase difference pixel 2A in which the right half is shaded and a phase difference pixel 2A in which the left half is shaded is used for measuring the phase difference, and the signal output from the phase difference pixel 2A is an image. Not used to build.

Further, even in the thirteenth variation of the pixel structure having the phase difference pixel 2A used for the image plane phase difference AF, a pixel in which the flat portion 53 is provided between the pixels 2 other than the phase difference pixel 2A. With the structure, it is possible to suppress the generation of diffracted light in the pixel separation region and prevent the generation of color mixing.

FIG. 24 is a diagram showing a 14th variation of the pixel structure.

In FIG. 24, the basic configuration of the solid-state image sensor 1 is the same as the configuration shown in FIG.
In the 14th variation of the pixel structure, the phase difference pixel 2A used for the image plane phase difference AF is not provided with the antireflection unit 48, and the pixel separation unit 54 is formed. There is.

Further, also in the 14th variation of the pixel structure, the pixel separation unit 54 can electrically separate the adjacent pixels 2 from each other, and the flat portion 53 is formed between the pixels 2 other than the phase difference pixel 2A. By adopting the pixel structure provided with the above, it is possible to suppress the generation of diffracted light in the pixel separation region and prevent the generation of color mixing.

FIG. 25 is a diagram showing a fifteenth variation of the pixel structure.

In FIG. 25, the basic configuration of the solid-state image sensor 1 is the same as the configuration shown in FIG.
In the fifteenth variation of the pixel structure, the phase difference pixel 2A used for the image plane phase difference AF is not provided with the antireflection unit 48, and the pixel separation unit 54A is formed. There is.

Further, also in the fifteenth variation of the pixel structure, the pixel separation unit 54A can electrically and optically separate the adjacent pixels 2 and between the pixels 2 other than the phase difference pixel 2A. By having a pixel structure in which the flat portion 53 is provided, it is possible to suppress the generation of diffracted light in the pixel separation region and prevent the generation of color mixing.

FIG. 26 is a diagram showing a sixteenth variation of the pixel structure.

In FIG. 26, the basic configuration of the solid-state image sensor 1 is the same as the configuration shown in FIG.
In the 16th variation of the pixel structure, the phase difference pixel 2A used for the image plane phase difference AF is not provided with the antireflection portion 48, and the pixel separation portion 54B is formed. There is.

Further, also in the 16th variation of the pixel structure, the pixel separation unit 54B can electrically and optically separate the adjacent pixels 2 and between the pixels 2 other than the phase difference pixel 2A. By having a pixel structure in which the flat portion 53 is provided, it is possible to suppress the generation of diffracted light in the pixel separation region and prevent the generation of color mixing.

<5. Application example to electronic devices>
The technique of the present disclosure is not limited to application to a solid-state image sensor. That is, the technique of the present disclosure is an image acquisition unit (photoelectric conversion unit) such as an image pickup device such as a digital still camera or a video camera, a portable terminal device having an image pickup function, or a copier using a solid-state image pickup device for an image reading unit. ) Can be applied to all electronic devices that use solid-state imaging devices. The solid-state image pickup device may be in the form of one chip, or may be in the form of a module having an image pickup function in which an image pickup unit and a signal processing unit or an optical system are packaged together.

FIG. 27 is a block diagram showing a configuration example of an image pickup device as an electronic device according to the present disclosure.

The image pickup device 200 of FIG. 27 includes an optical unit 201 including a lens group and the like, a solid-state image pickup device (imaging device) 202 in which the configuration of the solid-state image pickup device 1 of FIG. 1 is adopted, and a DSP (Digital Signal) which is a camera signal processing circuit. Processor) The circuit 203 is provided. The image pickup apparatus 200 also includes a frame memory 204, a display unit 205, a recording unit 206, an operation unit 207, and a power supply unit 208. The DSP circuit 203, the frame memory 204, the display unit 205, the recording unit 206, the operation unit 207, and the power supply unit 208 are connected to each other via the bus line 209.

The optical unit 201 captures incident light (image light) from the subject and forms an image on the image pickup surface of the solid-state image pickup device 202. The solid-state image sensor 202 converts the amount of incident light imaged on the image pickup surface by the optical unit 201 into an electric signal in pixel units and outputs it as a pixel signal. As the solid-state image sensor 202, the solid-state image sensor 1 of FIG. 1, that is, the solid-state image sensor with improved sensitivity while suppressing deterioration of color mixing can be used.

The display unit 205 comprises a panel-type display device such as a liquid crystal panel or an organic EL (Electro Luminescence) panel, and displays a moving image or a still image captured by the solid-state imaging device 202. The recording unit 206 records the moving image or still image captured by the solid-state image sensor 202 on a recording medium such as a hard disk or a semiconductor memory.

The operation unit 207 issues operation commands for various functions of the image pickup apparatus 200 under the operation of the user. The power supply unit 208 appropriately supplies various power sources that serve as operating power sources for the DSP circuit 203, the frame memory 204, the display unit 205, the recording unit 206, and the operation unit 207 to these supply targets.

As described above, by using the above-mentioned solid-state image sensor 1 as the solid-state image sensor 202, it is possible to improve the sensitivity while suppressing the deterioration of color mixing. Therefore, even in an image pickup device 200 such as a video camera, a digital still camera, and a camera module for mobile devices such as mobile phones, it is possible to improve the image quality of the captured image.

The embodiments of the present disclosure are not limited to the embodiments described above, and various modifications can be made without departing from the gist of the present disclosure.

In the above-mentioned example, a solid-state image pickup device in which the first conductive type is P-type and the second conductive type is N-type and electrons are used as signal charges has been described. Can also be applied. That is, the first conductive type is N-type, the second conductive type is P-type, and each of the above-mentioned semiconductor regions can be configured by the reverse conductive type semiconductor region.

Further, the technique of the present disclosure is not limited to application to a solid-state image sensor that detects the distribution of the incident light amount of visible light and captures it as an image, but also captures the distribution of the incident amount of infrared rays, X-rays, particles, etc. as an image. Applicable to all solid-state image sensors (physical quantity distribution detection devices) such as fingerprint detection sensors that detect the distribution of other physical quantities such as pressure and capacitance and capture images as images. It is possible.

The present disclosure may also have the following structure.
(1)
With the board
The first photoelectric conversion region provided on the substrate and
The second photoelectric conversion region next to the first photoelectric conversion region and provided on the substrate,
A trench provided between the first photoelectric conversion region and the second photoelectric conversion region,
A first moth-eye structure provided on the light receiving surface side of the substrate above the first photoelectric conversion region,
A second moth-eye structure provided on the light receiving surface side of the substrate above the second photoelectric conversion region.
An insulating film provided in at least a part of the trench and provided above the first moth-eye structure and the second moth-eye structure.
A solid-state image sensor having a light-shielding film provided above the insulating film and above the trench.
(2)
The solid-state image sensor according to (1), wherein the insulating film is provided between the substrate and the light-shielding film.
(3)
The solid-state image sensor according to (1) or (2) above, wherein the light-shielding film contains a metal.
(4)
The solid-state image sensor according to any one of (1) to (3) above, wherein the light-shielding film is aluminum.
(5)
The solid-state image pickup device according to any one of (1) to (4) above, wherein the side surface of the trench has a tapered shape in a cross-sectional view.
(6)
The solid-state image pickup device according to (5) above, wherein the taper shape is a forward taper of 0 to 30 °.
(7)
The first photoelectric conversion region and the first pixel having the first moth-eye structure,
The solid-state image sensor according to any one of (1) to (6), further comprising the second photoelectric conversion region and the second pixel having the second moth-eye structure.
(8)
The solid-state image sensor according to (7), wherein a substance that optically separates the first pixel and the second pixel is embedded in at least a part of the trench.
(9)
The solid-state image sensor according to (8) above, wherein the substance is a light-shielding substance having a light-shielding property.
(10)
The solid-state image sensor according to any one of (1) to (9) above, wherein a metal is embedded in at least a part of the trench.
(11)
The first moth-eye structure or the second moth-eye structure scatters light and
The solid-state image sensor according to any one of (1) to (10), wherein the trench reflects the light.
(12)
The first pixel has a first color filter above the first moth-eye structure.
The solid-state image sensor according to any one of (7) to (11), wherein the second pixel has a second color filter above the second moth-eye structure.
(13)
The first moth-eye structure has two or more recesses and has two or more recesses.
The solid-state image sensor according to any one of (7) to (12) above, wherein the second moth-eye structure has two or more recesses.
(14)
The solid-state image sensor according to any one of (11) to (13), wherein the width of the moth-eye structure is approximately 80% of the width of the color filter in a cross-sectional view.
(15)
The first color filter corresponds to the first color and
The second color filter corresponds to the second color and
In (13), the pitch of the recess of the first moth-eye structure below the first color filter and the pitch of the recess of the second moth-eye structure below the second color filter are the same. The solid-state image sensor described.
(16)
The first color filter corresponds to the first color and
The second color filter corresponds to the second color and
In (13), the number of the recesses of the first moth-eye structure below the first color filter is the same as the number of the recesses of the second moth-eye structure below the second color filter. The solid-state image sensor described.
(17)
The first color filter corresponds to the first color and
The second color filter corresponds to the second color and
In (13), the depth of the recess of the first moth-eye structure below the first color filter is the same as the depth of the recess of the second moth-eye structure below the second color filter. The solid-state image sensor described.
(18)
The solid-state image sensor according to any one of (1) to (17), wherein the amount of digging in the trench is larger than the width of the trench in the cross-sectional view.
(19)
The solid-state image sensor according to any one of (1) to (18), wherein the angle formed by the side surface forming the moth-eye structure and the side surface forming the trench is different in a cross-sectional view.
(20)
After forming a moth-eye structure on the surface of the substrate above the first photoelectric conversion region and the second photoelectric conversion region provided on the substrate,
A trench is formed in the substrate between the first photoelectric conversion region and the second photoelectric conversion region, and an insulating film is formed above the moth-eye structure so as to be provided in at least a part of the trench.
A method for manufacturing a solid-state image sensor that forms a light-shielding film above the insulating film and above the trench.
(21)
After forming a trench in the substrate between the first photoelectric conversion region and the second photoelectric conversion region provided on the substrate,
A moth-eye structure is formed on the surface of the substrate above the first photoelectric conversion region and the second photoelectric conversion region.
An insulating film is formed above the moth-eye structure so as to be provided in at least a part of the trench.
A method for manufacturing a solid-state image sensor that forms a light-shielding film above the insulating film and above the trench.
(22)
The moth-eye structure is formed by wet etching and
The method for manufacturing a solid-state image sensor according to (20), wherein the trench is formed by dry etching.
(23)
The moth-eye structure is formed by wet etching and
The method for manufacturing a solid-state image sensor according to (21), wherein the trench is formed by dry etching.

1 solid-state image sensor, 2 pixels, 3 pixel array part, 12 semiconductor substrate, 41, 42 semiconductor area, 45 pinning layer, 46 transparent insulating film, 47 pixel-to-pixel light-shielding part, 48 anti-reflection part, 49 light-shielding film, 50 flattening Film, 51 color filter layer, 52 on-chip lens, 101 metal shading part, 200 image sensor, 202 solid-state image sensor

Claims (23)

With the board
The first photoelectric conversion region provided on the substrate and
The second photoelectric conversion region next to the first photoelectric conversion region and provided on the substrate,
A trench provided between the first photoelectric conversion region and the second photoelectric conversion region, which has a longer depth than a width.
The first uneven structure provided on the light receiving surface side of the substrate above the first photoelectric conversion region and
A second uneven structure provided on the light receiving surface side of the substrate above the second photoelectric conversion region,
A first insulating film provided in at least a part of the trench and provided above the first concavo-convex structure and the second concavo-convex structure.
It has a light-shielding film provided above the first insulating film and above the trench.
The first insulating film is a photodetector containing hafnium oxide. The first concavo-convex structure and the second concavo-convex structure have recesses.
The photodetector according to claim 1, wherein the first side surface of the recess and the first side surface of the trench are non-parallel in cross-sectional view. The light-shielding film is provided above the substrate and is provided.
The photodetector according to claim 1, wherein the entire region of the first insulating film in contact with the light-shielding film is flat in cross-sectional view. The photodetector according to claim 3, further comprising a second insulating film provided above the first insulating film and in contact with the side surface of the light-shielding film. The photodetector according to claim 4, wherein the second insulating film is provided in contact with the upper surface of the light-shielding film. The photodetector according to claim 4 or 5, wherein the second insulating film contains the same material as the first insulating film. The photodetector according to claim 1, wherein the light-shielding film contains a metal. The photodetector according to claim 1, wherein the light-shielding film is aluminum. The photodetector according to claim 1, wherein the side surface of the trench has a tapered shape in a cross-sectional view. The photodetector according to claim 9, wherein the tapered shape is a forward taper in the range of 0 to 30 °. The first photoelectric conversion region and the first pixel having the first uneven structure,
The photodetector according to claim 1, further comprising the second photoelectric conversion region and the second pixel having the second uneven structure. The photodetector according to claim 11, wherein a light-shielding object having a light-shielding property for optically separating the first pixel and the second pixel is embedded in at least a part of the trench. The photodetector according to claim 1, wherein a metal is embedded in at least a part of the trench. The first concavo-convex structure or the second concavo-convex structure scatters light and
The photodetector according to claim 1, wherein the trench reflects the light. The first pixel has a first color filter above the first uneven structure.
The photodetector according to claim 11, wherein the second pixel has a second color filter above the second uneven structure. The first uneven structure has two or more recesses and has two or more recesses.
The photodetector according to claim 15, wherein the second uneven structure has two or more recesses. The photodetector according to claim 15, wherein the width of the first uneven structure is approximately 80% of the width of the first color filter in a cross-sectional view. The first color filter corresponds to the first color and
The second color filter corresponds to the second color and
16. The 16th aspect of the present invention, wherein the pitch of the concave portion of the first concave-convex structure below the first color filter and the pitch of the concave portion of the second concave-convex structure below the second color filter are the same. Light detector. The first color filter corresponds to the first color and
The second color filter corresponds to the second color and
16. The 16th aspect of the present invention, wherein the number of the recesses of the first concave-convex structure below the first color filter and the number of the recesses of the second concave-convex structure below the second color filter are the same. Photodetector. The first color filter corresponds to the first color and
The second color filter corresponds to the second color and
16. The 16th aspect of the present invention, wherein the depth of the concave portion of the first uneven structure below the first color filter is the same as the depth of the concave portion of the second concave-convex structure below the second color filter. Photodetector. After forming an uneven structure on the surface of the substrate above the first photoelectric conversion region and the second photoelectric conversion region provided on the substrate,
A trench having a depth length longer than a width length is formed on the substrate between the first photoelectric conversion region and the second photoelectric conversion region.
A first insulating film containing hafnium oxide is formed above the uneven structure so as to be provided in at least a part of the trench.
A method for manufacturing a photodetector that forms a light-shielding film above the first insulating film and above the trench. After forming a trench in the substrate between the first photoelectric conversion region and the second photoelectric conversion region provided on the substrate, the length of the depth is longer than the length of the width.
An uneven structure is formed on the surface of the substrate above the first photoelectric conversion region and the second photoelectric conversion region.
A first insulating film containing hafnium oxide is formed above the uneven structure so as to be provided in at least a part of the trench.
A method for manufacturing a photodetector that forms a light-shielding film above the first insulating film and above the trench. The uneven structure is formed by wet etching.
The method for manufacturing a photodetector according to claim 21 or 22, wherein the trench is formed by dry etching.

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