JP7290185B2 - Photodetector and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to a photodetector and its manufacturing method, and more particularly to a photodetector and its manufacturing method capable of improving sensitivity while suppressing deterioration of color mixture.

As a structure for preventing reflection of incident light in a solid-state imaging device, a so-called moth-eye structure has been proposed, in which a fine concave-convex structure is provided at the interface on the light-receiving surface side of a silicon layer in which a photodiode is formed (for example, See Patent Documents 1 and 2).

JP 2010-272612 A JP 2013-33864 A

However, although the moth-eye structure can prevent the reflection of incident light and improve the sensitivity, the scattering increases and the amount of light leaking into adjacent pixels increases, resulting in deterioration of color mixture.

The present disclosure has been made in view of such circumstances, and aims to improve sensitivity while suppressing deterioration of color mixture.

A photodetector according to a first aspect of the present disclosure includes a substrate, a first photoelectric conversion region provided on the substrate, and a second photoelectric conversion provided on the substrate adjacent to the first photoelectric conversion region. a trench having a depth longer than a width provided between the first photoelectric conversion region and the second photoelectric conversion region; and a trench above the first photoelectric conversion region. a first uneven structure provided on the light receiving surface side of the substrate; a second uneven structure provided on the light receiving surface side of the substrate above the second photoelectric conversion region; and at least part of the trench. a first insulating film provided above the first uneven structure and the second uneven structure; and a light shielding film provided above the first insulating film and above the trench. , the first insulating film includes hafnium oxide.

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

In the method for manufacturing a photodetector according to the second aspect of the present disclosure, after forming an uneven structure on the substrate surface above the first photoelectric conversion region and the second photoelectric conversion region provided on the substrate, A trench having a depth longer than a width is formed in the substrate between the conversion region and the second photoelectric conversion region, and the trench is provided in at least 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, a trench having a depth longer than a width is formed in the substrate between the first photoelectric conversion region and the second photoelectric conversion region provided on the substrate, and then the first photoelectric conversion region is formed. An uneven structure is formed on the substrate surface above the conversion region and the second photoelectric conversion region, and 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.

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 A trench whose depth is longer than its width is formed in the substrate between the regions, or the substrate between the first photoelectric conversion region and the second photoelectric conversion region provided in the substrate. Then, after trenches having a depth longer than the width are formed, an uneven structure is formed on the substrate surface 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, and a light shielding film is formed above the first insulating film and above the trench. .

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

According to the first and second aspects of the present disclosure, sensitivity can be improved while suppressing deterioration of color mixture.

1 is a diagram showing a schematic configuration of a solid-state imaging device according to the present disclosure; FIG. 4A and 4B are diagrams illustrating a cross-sectional configuration example of a pixel according to the first embodiment; FIG. 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 methods of a pixel. FIG. 4 is a diagram illustrating the effect of the pixel structure of the present disclosure; FIG. 4 is a diagram illustrating the effect of the pixel structure of the present disclosure; FIG. 10 is a diagram illustrating a cross-sectional configuration example of a pixel according to the second embodiment; 8A and 8B are diagrams illustrating a method for manufacturing a pixel according to the second embodiment; FIG. It is a figure explaining the optimal conditions of various parts of a pixel. FIG. 11 shows a first variation of the pixel structure; FIG. 11 shows a second variation of the pixel structure; FIG. 11 shows a third variation of the pixel structure; FIG. 11 shows a fourth variation of the pixel structure; FIG. 11 shows a fifth variation of the pixel structure; FIG. 11 shows a sixth variation of the pixel structure; FIG. 11 shows a seventh variation of the pixel structure; FIG. 11 shows an eighth variation of the pixel structure; FIG. 11 shows a ninth variation of the pixel structure; FIG. 10 illustrates a tenth variation of the pixel structure; FIG. 11 illustrates an eleventh variation of the pixel structure; FIG. 12 is a diagram showing a twelfth variation of the pixel structure; FIG. 13 is a diagram showing a thirteenth variation of the pixel structure; FIG. 14 is a diagram showing a fourteenth variation of the pixel structure; FIG. 15 is a diagram showing a fifteenth variation of the pixel structure; FIG. 16 is a diagram showing a sixteenth variation of the pixel structure; 1 is a block diagram showing a configuration example of an imaging device as an electronic device according to the present disclosure; FIG.

Hereinafter, modes for carrying out the present disclosure (hereinafter referred to as embodiments) will be described. The description will be given in the following order.
1. Schematic configuration example of solid-state imaging device 2. Pixel structure according to the first embodiment (pixel structure having an antireflection portion and an inter-pixel light shielding portion)
3. Pixel structure according to the second embodiment (pixel structure in which the inter-pixel light shielding portion is filled with metal)
4. Modified example of pixel structure5. Examples of application to electronic equipment

<1. Example of Schematic Configuration of Solid-State Imaging Device>
FIG. 1 shows a schematic configuration of a solid-state imaging device according to the present disclosure.

The solid-state imaging device 1 of FIG. 1 has a pixel array section 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 section therearound. configured as The peripheral circuit section 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 has a photodiode as a photoelectric conversion element and a plurality of pixel transistors. The plurality of pixel transistors are composed of, for example, four MOS transistors, ie, a transfer transistor, a selection transistor, a reset transistor, and an amplification transistor.

Pixel 2 can also 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 pixel transistor each. That is, in the shared pixel, the photodiodes and transfer transistors that constitute a plurality of unit pixels share another pixel transistor each.

The control circuit 8 receives an input clock and data instructing an operation mode, etc., and outputs data such as internal information of the solid-state imaging device 1 . That is, the control circuit 8 generates a clock signal and a control signal that serve as a reference for the operation of the vertical driving circuit 4, the column signal processing circuit 5, the horizontal driving circuit 6, etc. based on the vertical synchronizing signal, the horizontal synchronizing signal, and the master clock. do. 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 the pixel drive wiring 10, supplies pulses for driving the pixels 2 to the selected pixel drive wiring 10, and drives the pixels 2 in units of rows. That is, the vertical drive circuit 4 sequentially selectively scans the pixels 2 of the pixel array section 3 in the vertical direction on a row-by-row basis. 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 pixels 2, and performs signal processing such as noise removal on the signals output from the pixels 2 of one row for each pixel column. For example, the column signal processing circuit 5 performs signal processing such as CDS (Correlated Double Sampling) for removing pixel-specific fixed pattern noise and AD conversion.

The horizontal driving circuit 6 is composed of, for example, a shift register, and sequentially outputs horizontal scanning pulses to select each of the column signal processing circuits 5 in turn, and outputs pixel signals from each of the column signal processing circuits 5 to the horizontal signal line. 11 to output.

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 processed signals. For example, the output circuit 7 may 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 imaging device 1 configured as described above is a CMOS image sensor called a column AD system in which a column signal processing circuit 5 for performing CDS processing and AD conversion processing is arranged for each pixel column.

The solid-state imaging device 1 is a back-illuminated MOS-type solid-state imaging device in which light is incident from the back side opposite to the front side of the semiconductor substrate 12 on which the pixel transistors are formed.

<2. Pixel Structure According to First Embodiment>
<Example of cross-sectional configuration of pixel>
FIG. 2 is a diagram showing a cross-sectional configuration example of the pixel 2 according to the first embodiment.

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

The semiconductor substrate 12 is made of silicon (Si), for example, and has a thickness of 1 to 6 μm, for example. In the semiconductor substrate 12, for example, an N-type (second conductivity type) semiconductor region 42 is formed in each pixel 2 in a P-type (first conductivity type) semiconductor region 41, so that the photodiode PD is formed on a pixel-by-pixel basis. is formed in The P-type semiconductor regions 41 facing both the front and back surfaces of the semiconductor substrate 12 also serve as hole charge accumulation regions for suppressing dark current.

At the pixel boundary of each pixel 2 between the N-type semiconductor regions 42, the P-type semiconductor regions 41 are deeply dug as shown in FIG. is included.

The interface (light-receiving surface side interface) of the P-type semiconductor region 41 above the N-type semiconductor region 42 serving as a charge accumulation region has a so-called moth-eye structure in which fine irregularities are formed to prevent reflection of incident light. An antireflection portion 48 is configured. In the anti-reflection portion 48, the pitch of the spindle-shaped protrusions corresponding to the period of the protrusions is set in the range of 40 nm to 200 nm, for example.

The multilayer wiring layer 21 has a plurality of wiring layers 43 and an interlayer insulating film 44 . In the multilayer wiring layer 21, a plurality of pixel transistors Tr are also formed for reading out 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 using a high dielectric material having negative fixed charges so that a positive charge (hole) accumulation region is formed at the interface with the semiconductor substrate 12 to suppress the generation of dark current. there is By forming the pinning layer 45 so as to have negative fixed charges, the negative fixed charges apply an electric field to the interface with the semiconductor substrate 12, forming a positive charge accumulation region.

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

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

The transparent insulating film 46 is made of a material that transmits light, has insulating properties, 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 ), lanthanum oxide (La ₂ O ₃ ), praseodymium 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 ), gadolinium oxide (Gd ₂ O ₃ ), terbium oxide (Tb ₂ O ₃ ), dysprosium oxide ( _Dy2O3 ), holmium oxide ( _{Ho2O3 ) ,} thulium _{oxide (} Tm2O3 ₎ , ytterbium oxide ( _{Yb2O3 )} , lutetium oxide ( _Lu2O3 ), yttrium oxide ( _{Y2O3 )} , resins and the like can be used alone or in combination.

An antireflection film may be laminated on the pinning layer 45 before forming the transparent insulating film 46 . Silicon nitride (SiN), hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), tantalum oxide (Ta ₂ O ₅ ), titanium oxide (TiO ₂ ), lanthanum oxide ( _La2O3 ), _praseodymium oxide ( _Pr2O3 ), cerium oxide _{( CeO2} ), neodymium oxide ( _Nd2O3 ), promethium oxide ( _Pm2O3 ), samarium _oxide ( _{Sm 2} O ₃ ), europium oxide (Eu ₂ O ₃ ), gadolinium oxide (Gd ₂ O ₃ ), terbium oxide (Tb ₂ O ₃ ), dysprosium oxide (Dy ₂ O ₃ ), holmium 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 top surface of the antireflection portion 48 having the moth-eye structure, or may be formed on both the top surface of the antireflection portion 48 and the side surface of the inter-pixel light shielding portion 47 as with the pinning layer 45 . It may be a film.

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

A planarizing 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 planarizing film 50, for example, an organic material such as resin can be used.

A red, green, or blue color filter layer 51 is formed on the planarization film 50 for each pixel. The color filter layer 51 is formed, for example, by spin-coating a photosensitive resin containing dyes such as pigments and dyes. The colors Red, Green, and Blue are arranged in a Bayer arrangement, for example, but may be arranged in 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 made of, for example, a resin material such as styrene resin, acrylic resin, styrene-acrylic copolymer resin, or siloxane resin. The incident light is condensed by the on-chip lens 52 , and the condensed light is efficiently incident on the photodiode PD via the color filter layer 51 .

Each pixel 2 of the pixel array section 3 of the solid-state imaging device 1 is configured as described above.

<Method for Manufacturing Pixel According to First Embodiment>
Next, a method for manufacturing the pixel 2 according to the first embodiment will be described with reference to FIGS. 3 and 4. FIG.

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

Then, based on the patterned photoresist 81, the semiconductor substrate 12 is dry-etched to form a moth-eye recessed portion of the antireflection portion 48 as shown in FIG. 3B. Photoresist 81 is removed. The moth-eye structure of the antireflection portion 48 can also be formed by wet etching instead of dry etching.

Next, as shown in FIG. 3C, a 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 recessed portion of the inter-pixel light shielding portion 47 is opened by lithography. Photoresist 82 is patterned as follows.

Then, based on the patterned photoresist 82, the semiconductor substrate 12 is subjected to an anisotropic dry etching process to form the trench structure of the inter-pixel light shielding portion 47 as shown in FIG. 3D. , and then the photoresist 82 is removed. As a result, an inter-pixel light shielding portion 47 having a trench structure is formed.

The inter-pixel light-shielding portion 47 that needs to be dug deep into the semiconductor substrate 12 is formed by an anisotropic etching process. As a result, the inter-pixel light shielding portion 47 can be made into a dug 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 inter-pixel light shielding portion 47 having a trench structure are formed is subjected to pinning by, for example, a CVD (Chemical Vapor Deposition) method. A 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 film formation method with high filling property such as the CVD method or by using a filling material. As a result, the transparent insulating film 46 is filled also in the inter-pixel light shielding portion 47 that has been dug.

Then, as shown in FIG. 4C, a light-shielding film 49 is formed by lithography only in the regions between pixels, and then, as shown in FIG. A lens 52 is formed in that order.

The solid-state imaging device 1 having the structure shown in FIG. 2 can be manufactured as described above.

<Another method for manufacturing a pixel according to the first embodiment>
In the manufacturing method described above, first, the antireflection portion 48 having a moth-eye structure is formed, and then the inter-pixel light shielding portion 47 having a trench structure is formed. However, the order of forming the antireflection portion 48 and the inter-pixel light shielding portion 47 may be reversed.

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

First, as shown in FIG. 5A, a photoresist 91 is applied to the upper surface of the P-type semiconductor region 41 on the back side of the semiconductor substrate 12, and a trench portion of the inter-pixel light shielding portion 47 is opened by lithography. Photoresist 91 is patterned.

Then, based on the patterned photoresist 91, the semiconductor substrate 12 is subjected to an anisotropic dry etching process to form the trench portion of the inter-pixel light shielding portion 47 as shown in FIG. 5B. , and then the photoresist 91 is removed. As a result, an inter-pixel light shielding portion 47 having a trench structure is formed.

Next, as shown in FIG. 5C, a photoresist 92 is applied to the upper surface of the P-type semiconductor region 41, and the photoresist is applied by lithography so that the recessed portion of the moth-eye structure of the antireflection portion 48 is opened. 92 are patterned.

Then, based on the patterned photoresist 92, the semiconductor substrate 12 is dry-etched to form a moth-eye recessed portion of the antireflection portion 48 as shown in FIG. 5D. Photoresist 92 is removed. Thereby, 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 wet etching instead of dry etching.

The state shown in FIG. 5D is the same as the state shown in FIG. 3D. Therefore, the subsequent manufacturing method of the transparent insulating film 46, the planarizing film 50, etc. is the same as in FIG.

<Effect of Pixel Structure According to First Embodiment>
FIG. 6 is a diagram for explaining the effect of the pixel structure of the pixel 2 shown in FIG.

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

The anti-reflection portion 48 has a moth-eye structure to prevent reflection of incident light. Thereby, the sensitivity of the solid-state imaging device 1 can be improved.

FIG. 6B is a diagram for explaining 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 sometimes passes through the photoelectric conversion regions (semiconductor regions 41 and 42). The inter-pixel light shielding portion 47 has the effect of reflecting incident light scattered by the antireflection portion 48 having a moth-eye structure and confining the incident light within the photoelectric conversion region. As a result, since the optical distance for silicon absorption is extended, the sensitivity can be improved.

Assuming that the refractive index of the inter-pixel light shielding portion 47 is n1=1.5 (equivalent to SiO ₂ ) and the refractive index of the semiconductor region 41 in which the photoelectric conversion region is formed is n2=4.0, the refractive index difference (n1<n2) leads to Since a wave path effect (photoelectric conversion region: core, inter-pixel light shielding portion 47: clad) occurs, incident light is confined within the photoelectric conversion region. Although the moth-eye structure has the disadvantage of worsening color mixing due to light scattering, the worsening of color mixing can be canceled by combining it with the inter-pixel light shielding portion 47, and furthermore, by increasing the angle of incidence traveling through the photoelectric conversion region, photoelectric Generates the merit of improving conversion efficiency.

FIG. 7 is a diagram showing the effect of the pixel structure of pixel 2 of the present disclosure compared to other structures.

Each of FIGS. 7A to 7D has a two-stage configuration, the upper diagram shows a cross-sectional structure diagram of a pixel, and the lower diagram shows a pixel having a pixel structure in the upper stage with green parallel light. 2 is a distribution diagram showing light intensity in a semiconductor substrate 12 when light is incident. FIG. 7A to 7D, portions corresponding to the structure of the pixel 2 in FIG. 2 are given the same reference numerals for easy understanding.

The upper part of FIG. 7A shows the pixel structure of a general solid-state imaging device, which does not have a moth-eye antireflection part 48 or an inter-pixel light shielding part 47 with a trench structure, and the pinning layer 45A is a P-type semiconductor region. 41 shows a pixel structure formed flat on 41. FIG.

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

The upper part of FIG. 7B shows a pixel structure in which only an antireflection portion 48 having a moth-eye structure is formed on a 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 with the moth-eye structure leaks into the adjacent blue pixel. Therefore, the light sensitivity of the green pixel is lowered to 0.90, while the light sensitivity of the adjacent blue pixel is increased to 0.16. The total photosensitivity of two pixels is 1.06.

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

Looking at the light intensity distribution diagram shown in the lower part of FIG. 7C, the pixel structure is almost the same as in FIG. , which is 1.07.

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

Looking at the light intensity distribution chart shown in the lower part of FIG. is prevented by the inter-pixel light shielding portion 47 . As a result, the light sensitivity of the green pixel increases to 1.11, and the light sensitivity of the blue pixel is 0.07, which is the same level as the pixel structure of FIG. 7C. The total photosensitivity of 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 having the moth-eye structure prevents upward reflection, and the inter-pixel light shielding portion 47 prevents the light from being scattered by the antireflection portion 48 . It is possible to prevent incident light from leaking into adjacent pixels. Therefore, it is possible to improve the sensitivity while suppressing deterioration of color mixture.

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

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

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

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

In the solid-state imaging device 1 of the second embodiment, by further providing the metal light shielding portion 101, it is possible to further suppress color mixture.

<Method for Manufacturing Pixel According to Second Embodiment>
A method for manufacturing the pixel 2 according to the second embodiment will be described with reference to FIG.

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

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

Next, as shown in FIG. 9C, the metal light shielding portion 101 and the light shielding film 49 are formed at the same time by patterning only the regions between the pixels by lithography using, for example, tungsten (W). . The metal light shielding portion 101 and the light shielding film 49 may of course be formed separately using different metal materials.

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

<Example of optimal conditions for pixel structure>
Optimal conditions for various locations of pixel 2 will be described with reference to FIG.

(Moth-eye placement area L1 of antireflection portion 48)
In the above-described embodiment, the anti-reflection portion 48 having a moth-eye structure is formed in the entire light-receiving surface side of the semiconductor regions 41 and 42 in which the photodiodes PD are formed. However, as shown in FIG. 10, the moth-eye arrangement area L1 (moth-eye arrangement width L1) of the anti-reflection portion 48 is formed only in the central part of the pixel with a predetermined proportion of the pixel area L4 (pixel width L4). can do. The moth-eye arrangement area L1 of the antireflection portion 48 is preferably an area that is approximately 80% of the pixel area L4.

The light collected by the on-chip lens 52 is focused on the center of the sensor (photodiode PD), which is the photoelectric conversion area. Therefore, the closer to the sensor center, the stronger the light intensity, and the farther away from the sensor center, the weaker the light intensity. In areas away from the center of the sensor, there are many diffracted light noise components, that is, mixed color noise components to adjacent pixels. Therefore, by not forming the 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 area L1 of the antireflection part 48 varies depending on the difference in the upper layer structure such as pixel size, on-chip lens curvature, and total thickness of the pixel 2, but the on-chip lens 52 is usually located at the center 8 of the sensor area. In order to condense the light spot on a 10% area, it is desirable that the area is approximately 80% of the pixel area L4.

In addition, the size of the convex portion (spindle shape) of the moth-eye structure can be formed so as to be different for each color. As the size of the protrusions, height, arrangement area (area where the protrusions are formed in plan view), and pitch can be defined.

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

In addition, the arrangement area of the convex portion is made smaller as the wavelength of the incident light is shorter. That is, if the arrangement area of the protrusion of the red pixel 2 is x _R , the arrangement area of the protrusion of the green pixel 2 is x _G , and the arrangement area of the protrusion of the blue pixel 2 is x _B , then x _R >x It can be formed so that the magnitude relationship of _G > _xB is established. The width of the arrangement area in one direction corresponds to the moth-eye arrangement width L1 in FIG.

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

(Groove width L2 of inter-pixel light shielding portion 47)
The groove width L2 of the inter-pixel light shielding portion 47 required to prevent incident light from leaking into adjacent pixels and cause total reflection will be examined.

The groove width L2 of the inter-pixel light shielding portion 47 is set to the wavelength λ of incident light of 600 nm, the refractive index n2 of the semiconductor region 41 to 4.0, the refractive index n1 of the inter-pixel light shielding portion 47 to 1.5 (equivalent to SiO ₂ ), and the semiconductor region 41 to Assuming that the angle of incidence θ to the inter-pixel light shielding portion 47 is 60°, it should be 40 nm or more. However, from the viewpoint of the margin that satisfies the optical characteristics and the embeddability in the process, 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 inter-pixel light shielding portion 47)
The depth L3 of the inter-pixel light shielding portion 47 will be examined.

The larger the depth L3 of the inter-pixel light shielding portion 47, the higher the effect of suppressing color mixture. However, when the excavation amount exceeds a certain amount, the degree of suppression of color mixing becomes saturated. Also, the focal position and scattering intensity depend on the incident light wavelength. Specifically, when the wavelength is short, the focal position is high and the scattering intensity is high, so the color mixture in the shallow region is large, so the amount of excavation may be small. On the other hand, if the wavelength is long, the focal position is low and the scattering intensity is low, so color mixture in the deep region is large. From the above, it is desirable that the recessed amount L3 of the inter-pixel light shielding portion 47 is equal to or greater than the wavelength of the incident light. For example, it is desirable that the depth L3 of the blue pixel 2 is 450 nm or more, the depth L3 of the green pixel 2 is 550 nm or more, and the depth 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 dug shape without a taper using an anisotropic dry etching process in order to maximize the waveguide function and not reduce the sensor area. I decided to

However, if the inter-pixel light-shielding portion 47 and the N-type semiconductor region 42 are sufficiently separated from each other and the tapered shape of the inter-pixel light-shielding portion 47 does not affect the area of the photodiode PD, then the inter-pixel light-shielding The shape of the portion 47 may be tapered. For example, if the refractive index n1 of the interpixel light shielding portion 47 is 1.5 (corresponding to SiO ₂ ) and the refractive index n2 of the P-type semiconductor region 41 is 4.0, the interface reflectance is extremely high. , a forward tapered shape or a reverse tapered shape within the range of 0 to 30°.

<4. Modified Example of Pixel Structure>
A plurality of variations of the pixel structure will be described with reference to FIGS. 11 to 26. FIG. 11 to 26, description will be made using a pixel structure that is more simplified than the cross-sectional configuration examples shown in FIG. 2 and FIG. There are some attached.

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

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

As shown in FIG. 11, the solid-state imaging device 1 includes an antireflection film 111, a transparent insulating film 46, and a color filter on a semiconductor substrate 12 in which an N-type semiconductor region 42 forming a photodiode PD is formed for each pixel 2. A layer 51 and an on-chip lens 52 are laminated.

The antireflection film 111 has, for example, a laminated structure in which a fixed charge film and an oxide film are laminated. . Specifically, hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), STO (Strontium Titan Oxide), or 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. In FIG.

Furthermore, a light shielding film 49 is formed between the pixels 2 so as to be laminated on the antireflection film 111 . A single-layer metal film such as titanium (Ti), titanium nitride (TiN), tungsten (W), aluminum (Al), or tungsten nitride (WN) is used for the light shielding film 49 . Alternatively, 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 as the light shielding film 49 .

In the solid-state imaging device 1 configured as described above, in the first variation of the pixel structure, a region having a predetermined width in which the antireflection portion 48 is not formed is provided between the pixels 2 at the interface on the light receiving surface side of the semiconductor substrate 12. provides a flat portion 53 . As described above, the antireflection portion 48 is provided by forming a moth-eye structure (fine concave-convex structure). A flat portion 53 is provided by . In this way, by adopting a pixel structure in which the flat portion 53 is provided, it is possible to suppress the occurrence of diffracted light in an area (pixel separation area) having a predetermined width in the vicinity of another adjacent pixel 2 and prevent the occurrence of color mixture. be able to.

That is, when a moth-eye structure is formed on the semiconductor substrate 12, diffraction of vertically incident light occurs. It is known that the percentage of incident light increases.

On the other hand, in the solid-state imaging device 1, by providing the flat portion 53 in a region of a predetermined width between the pixels 2 where the diffracted light is likely to leak to the other adjacent pixels 2, the flat portion 53 can absorb the vertically incident light. Since no diffraction occurs, it is possible to prevent color mixture from occurring.

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

12, the basic configuration of the solid-state imaging device 1 is common to the configuration shown in FIG.
Then, in the second variation of the pixel structure, a pixel separating portion 54 separating the pixels 2 from each other is formed on the semiconductor substrate 12 .

The pixel separation section 54 is formed by digging a trench between the N-type semiconductor regions 42 that constitute the photodiode PD, forming an aluminum oxide film 113 on the inner surface of the trench, and further forming a silicon oxide film 114. are formed by embedding an insulator 55 in the trenches.

By configuring the pixel isolation section 54 in this manner, the adjacent pixels 2 are electrically isolated from each other by the insulator 55 embedded in the trench. This can prevent electric charges generated inside the semiconductor substrate 12 from leaking to the adjacent pixels 2 .

Also in the second variation of the pixel structure, by adopting a pixel structure in which the flat portion 53 is provided, it is possible to suppress the occurrence of diffracted light in the pixel separation region and prevent the occurrence of color mixture.

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

13, the basic configuration of the solid-state imaging device 1 is common to the configuration shown in FIG.
Then, in the third variation of the pixel structure, a pixel isolation portion 54A is formed in the semiconductor substrate 12 to isolate the pixels 2 from each other.

The pixel separation portion 54A is formed by digging a trench between the N-type semiconductor regions 42 that constitute the photodiode PD, forming an aluminum oxide film 113 on the inner surface of the trench, and forming a silicon oxide film 114. An insulator 55 is embedded in the trench, and a light shielding material 56 is embedded when forming a light shielding film 49 inside the insulator 55 . The light shielding material 56 is made of a light shielding metal and is formed integrally with the light shielding film 49 .

By configuring the pixel separation section 54A in this way, the adjacent pixels 2 are electrically isolated from each other by the insulator 55 embedded in the trench and optically isolated from each other by the light shielding material 56 . As a result, it is possible to prevent electric charges generated inside the semiconductor substrate 12 from leaking to the adjacent pixels 2 and prevent light from oblique directions from leaking to the adjacent pixels 2 .

Also in the third variation of the pixel structure, by adopting a pixel structure in which the flat portion 53 is provided, it is possible to suppress the occurrence of diffracted light in the pixel separation region and prevent the occurrence of color mixture.

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

14, the basic configuration of the solid-state imaging device 1 is common to the configuration shown in FIG.
Then, in the fourth variation of the pixel structure, a pixel isolation portion 54B is formed in the semiconductor substrate 12 to isolate the pixels 2 from each other.

The pixel separation portion 54B is formed by digging a trench between the N-type semiconductor regions 42 that constitute the photodiode PD, forming an aluminum oxide film 113 on the inner surface of the trench, and forming a silicon oxide film 114. An insulator 55 is embedded in the trench, and a light shielding material 56 is embedded in the trench. It should be noted that the pixel separation portion 54B is configured such that the light shielding film 49 is not provided on the flat portion 53 .

By configuring the pixel separation section 54B in this way, the adjacent pixels 2 are electrically separated from each other by the insulator 55 embedded in the trench and optically separated from each other by the light blocking member 56 . As a result, it is possible to prevent electric charges generated inside the semiconductor substrate 12 from leaking to the adjacent pixels 2 and prevent light from oblique directions from leaking to the adjacent pixels 2 .

Also in the fourth variation of the pixel structure, by adopting a pixel structure in which the flat portion 53 is provided, it is possible to suppress the occurrence of diffracted light in the pixel isolation region and prevent the occurrence of color mixture.

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

15, the basic configuration of the solid-state imaging device 1 is common to 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 forming the moth-eye structure becomes shallow in the vicinity of the periphery of the pixel 2. FIG.

That is, as shown in FIG. 15, the antireflection portion 48A is, for example, closer to the neighboring pixels 2 in the peripheral portion of the pixel 2 than the antireflection portion 48 shown in FIG. The unevenness forming the moth-eye structure is shallow in some parts.

In this way, by forming the concave-convex structure in the peripheral portion of the pixel 2 with a shallow depth, it is possible to suppress the generation of diffracted light in the peripheral portion. Also in the fifth variation of the pixel structure, by adopting a pixel structure in which the flat portion 53 is provided, it is possible to suppress the occurrence of diffracted light in the pixel separation region and further prevent the occurrence of color mixture.

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

16, the basic configuration of the solid-state imaging device 1 is common to 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 forming the moth-eye structure is shallow in the peripheral portion of the pixel 2, and the pixel separation portion 54 is formed to have a shallow depth. formed.

By forming such an antireflection portion 48A, generation of diffracted light in the peripheral portion of the pixel 2 can be suppressed, and the pixel separation portion 54 can electrically separate adjacent pixels 2 from each other. can be done. Also in the sixth variation of the pixel structure, by adopting a pixel structure in which the flat portion 53 is provided, it is possible to suppress the occurrence of diffracted light in the pixel separation region and further prevent the occurrence of color mixture.

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

17, the basic configuration of the solid-state imaging device 1 is common to 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 forming the moth-eye structure is shallow in the vicinity of the periphery of the pixel 2, and the pixel separation portion 54A 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 separates the adjacent pixels 2 from each other. can be separated. Also in the seventh variation of the pixel structure, by adopting a pixel structure in which the flat portion 53 is provided, it is possible to suppress the occurrence of diffracted light in the pixel separation region and further prevent the occurrence of color mixture.

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

18, the basic configuration of the solid-state imaging device 1 is common to the configuration shown in FIG.
In the eighth variation of the pixel structure, the shape of the antireflection portion 48A is formed such that the depth of the unevenness forming the moth-eye structure is shallow in the vicinity of the periphery of the pixel 2, and the pixel separation portion 54B 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 separates the adjacent pixels 2 from each other. can be separated. Also in the eighth variation of the pixel structure, by adopting a pixel structure in which the flat portion 53 is provided, it is possible to suppress the occurrence of diffracted light in the pixel separation region and further prevent the occurrence of color mixture.

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

19, the basic configuration of the solid-state imaging device 1 is common to the configuration shown in FIG.
Then, in the ninth variation of the pixel structure, the antireflection portion 48B is formed, for example, in a narrower area than the antireflection portion 48 of FIG.

That is, as shown in FIG. 19, the antireflection portion 48B is in the vicinity of the pixel 2, that is, in the vicinity of the other adjacent pixels 2, compared with the antireflection portion 48 shown in FIG. In some parts, the area forming the moth-eye structure is reduced. Thereby, the flat portion 53A is formed wider than the flat portion 53 of FIG.

Thus, by providing a wide flat portion 53A without forming a 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. As a result, even in the ninth variation of the pixel structure, it is possible to suppress the occurrence of diffracted light in the pixel separation region and further prevent the occurrence of color mixture.

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

20, the basic configuration of the solid-state imaging device 1 is common to the configuration shown in FIG.
In addition, in the tenth variation of the pixel structure, the region where the antireflection portion 48B is formed is narrowed, and the pixel isolation portion 54 is formed.

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

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

21, the basic configuration of the solid-state imaging device 1 is common to the configuration shown in FIG.
In addition, 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, generation of diffracted light in the peripheral portion of the pixel 2 can be suppressed, and the pixel separation portion 54A electrically and optically separates the adjacent pixels 2 from each other. can be separated. Also in the 21st variation of the pixel structure, by adopting a pixel structure in which the flat portion 53A is widely provided, it is possible to suppress the occurrence of diffracted light in the pixel separation region and further prevent the occurrence of color mixture.

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

22, the basic configuration of the solid-state imaging device 1 is common to 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 separates the adjacent pixels 2 from each other. can be separated. Also in the 21st variation of the pixel structure, by adopting a pixel structure in which the flat portion 53A is widely provided, it is possible to suppress the occurrence of diffracted light in the pixel separation region and further prevent the occurrence of color mixture.

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

23, the basic configuration of the solid-state imaging device 1 is common to the configuration shown in FIG.
In the thirteenth variation of the pixel structure, a phase difference pixel 2A used for image plane phase difference AF (Auto Focus) is provided. is not provided. The phase difference pixel 2A outputs a signal used for autofocus control using the phase difference on the image plane. .

As shown in FIG. 23, in the phase difference pixel 2A used for image plane phase difference AF, a light shielding film 49A is formed so as to shield approximately half of the aperture from light. For example, a pair of a phase difference pixel 2A whose right half is shielded from light and a phase difference pixel 2A whose left half is shielded is used for phase difference measurement, and the signal output from the phase difference pixel 2A is an image not used for construction.

Also in the thirteenth variation of the pixel structure having the phase difference pixels 2A used for such image plane phase difference AF, the pixels 2 other than the phase difference pixels 2A are provided with the flat portions 53. By adopting the structure, it is possible to suppress the generation of diffracted light in the pixel separation region and prevent the generation of color mixture.

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

24, the basic configuration of the solid-state imaging device 1 is common to the configuration shown in FIG.
In the fourteenth variation of the pixel structure, the antireflection portion 48 is not provided in the phase difference pixel 2A used for the image plane phase difference AF, and the pixel separation portion 54 is formed. there is

Also in the fourteenth variation of the pixel structure, the pixel separating portion 54 can electrically separate the adjacent pixels 2, and the flat portion 53 between the pixels 2 other than the phase difference pixels 2A can be separated from each other. By adopting a pixel structure in which the .

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

25, the basic configuration of the solid-state imaging device 1 is common to the configuration shown in FIG.
In the fifteenth variation of the pixel structure, the antireflection portion 48 is not provided in the phase difference pixel 2A used for the image plane phase difference AF, and the pixel separating portion 54A is formed. there is

Also in the fifteenth variation of the pixel structure, the pixel separating portion 54A can electrically and optically separate the adjacent pixels 2, and between the pixels 2 other than the phase difference pixel 2A By adopting 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 mixture.

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

26, the basic configuration of the solid-state imaging device 1 is common to the configuration shown in FIG.
In the sixteenth variation of the pixel structure, the antireflection portion 48 is not provided in the phase difference pixel 2A used for the image plane phase difference AF, and the pixel separation portion 54B is formed. there is

Also in the sixteenth variation of the pixel structure, the pixel separating section 54B can electrically and optically separate the adjacent pixels 2, and between the pixels 2 other than the phase difference pixel 2A By adopting 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 mixture.

<5. Examples of application to electronic devices>
The technology of the present disclosure is not limited to application to solid-state imaging devices. That is, the technology of the present disclosure can be applied to an image capture unit (photoelectric conversion unit ) can be applied to general electronic equipment that uses a solid-state imaging device. The solid-state imaging device may be formed as a single chip, or may be in a modular form having an imaging function in which an imaging section and a signal processing section or an optical system are packaged together.

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

An imaging device 200 in FIG. 27 includes an optical unit 201 including a lens group, etc., a solid-state imaging device (imaging device) 202 adopting the configuration of the solid-state imaging device 1 in FIG. Processor) circuit 203 . The imaging device 200 also includes a frame memory 204 , a display section 205 , a recording section 206 , an operation section 207 and a power supply section 208 . DSP circuit 203 , frame memory 204 , display unit 205 , recording unit 206 , operation unit 207 and power supply unit 208 are interconnected via bus line 209 .

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

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

The operation unit 207 issues operation commands for various functions of the imaging apparatus 200 under user's operation. The power supply unit 208 appropriately supplies various power supplies as operating power supplies 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-described solid-state imaging device 1 as the solid-state imaging device 202, sensitivity can be improved while suppressing deterioration of color mixture. Therefore, even in the imaging device 200 such as a video camera, a digital still camera, and a camera module for a mobile device such as a mobile phone, 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 example, the first conductivity type is P-type, the second conductivity type is N-type, and the solid-state imaging device using electrons as signal charges has been described. can also be applied. That is, the first conductivity type can be N-type, the second conductivity type can be P-type, and each of the semiconductor regions described above can be composed of semiconductor regions of opposite conductivity types.

In addition, the technology of the present disclosure is not limited to application to a solid-state imaging device that detects the distribution of the incident light amount of visible light and images it as an image. In a broad sense, it applies to solid-state imaging devices (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.

Note that the present disclosure can also take the following configurations.
(1)
a substrate;
a first photoelectric conversion region provided on the substrate;
a second photoelectric conversion region provided on the substrate adjacent to the first photoelectric conversion region;
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 part of the trench and provided above the first moth-eye structure and the second moth-eye structure;
and a light shielding film provided above the insulating film and above the trench.
(2)
The solid-state imaging device according to (1), wherein the insulating film is provided between the substrate and the light shielding film.
(3)
The solid-state imaging device according to (1) or (2), wherein the light shielding film contains a metal.
(4)
The solid-state imaging device according to any one of (1) to (3), wherein the light shielding film is made of aluminum.
(5)
The solid-state imaging device according to any one of (1) to (4), wherein side surfaces of the trench are tapered in a cross-sectional view.
(6)
The solid-state imaging device according to (5), wherein the tapered shape is a forward taper of 0 to 30 degrees.
(7)
a first pixel having the first photoelectric conversion region and the first moth-eye structure;
The solid-state imaging device according to any one of (1) to (6), further comprising a second pixel having the second photoelectric conversion region and the second moth-eye structure.
(8)
The solid-state imaging device according to (7), wherein at least part of the trench is filled with a substance that optically separates the first pixel and the second pixel.
(9)
The solid-state imaging device according to (8), wherein the substance is a light-shielding substance having a light-shielding property.
(10)
The solid-state imaging device according to any one of (1) to (9), wherein at least part of the trench is filled with metal.
(11)
The first moth-eye structure or the second moth-eye structure scatters light,
The solid-state imaging device 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 imaging device 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,
The solid-state imaging device according to any one of (7) to (12), wherein the second moth-eye structure has two or more concave portions.
(14)
The solid-state imaging device 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 a first color;
the second color filter corresponds to a second color;
(13), wherein the pitch of the recesses of the first moth-eye structure below the first color filter is the same as the pitch of the recesses of the second moth-eye structure below the second color filter; The solid-state imaging device described.
(16)
the first color filter corresponds to a first color;
the second color filter corresponds to a second color;
(13) wherein the number of recesses of the first moth-eye structure below the first color filter is the same as the number of recesses of the second moth-eye structure below the second color filter The solid-state imaging device described.
(17)
the first color filter corresponds to a first color;
the second color filter corresponds to a second color;
The depth of the concave portion of the first moth-eye structure below the first color filter and the depth of the concave portion of the second moth-eye structure below the second color filter are the same. The solid-state imaging device described.
(18)
The solid-state imaging device according to any one of (1) to (17), wherein the depth of the trench is larger than the groove width of the trench in a cross-sectional view.
(19)
The solid-state imaging device according to any one of (1) to (18), wherein, in a cross-sectional view, an angle between a side surface forming the moth-eye structure and a side surface forming the trench is different.
(20)
After forming a moth-eye structure on the substrate surface above the first photoelectric conversion region and the second photoelectric conversion region provided on the substrate,
forming a trench in the substrate between the first photoelectric conversion region and the second photoelectric conversion region; forming an insulating film above the moth-eye structure so as to be provided in at least a part of the trench;
A method of manufacturing a solid-state imaging device, comprising forming 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 in the substrate,
forming a moth-eye structure on the substrate surface above the first photoelectric conversion region and the second photoelectric conversion region;
forming an insulating film above the moth-eye structure so as to be provided in at least part of the trench;
A method of manufacturing a solid-state imaging device, comprising forming a light shielding film above the insulating film and above the trench.
(22)
The moth-eye structure is formed by wet etching,
The method of manufacturing a solid-state imaging device according to (20), wherein the trench is formed by dry etching.
(23)
The moth-eye structure is formed by wet etching,
The method of manufacturing a solid-state imaging device according to (21), wherein the trench is formed by dry etching.

1 solid-state imaging device, 2 pixels, 3 pixel array portion, 12 semiconductor substrate, 41, 42 semiconductor regions, 45 pinning layer, 46 transparent insulating film, 47 light shielding portion between pixels, 48 antireflection portion, 49 light shielding film, 50 flattening Membrane 51 Color filter layer 52 On-chip lens 101 Metal light shielding part 200 Imaging device 202 Solid-state imaging device

Claims (23)

a substrate;
a first photoelectric conversion region provided on the substrate;
a second photoelectric conversion region provided on the substrate adjacent to the first photoelectric conversion region;
a trench having a depth longer than a width provided between the first photoelectric conversion region and the second photoelectric conversion region;
a first uneven structure provided on the light receiving surface side of the substrate above the first photoelectric conversion region;
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 part of the trench and provided above the first uneven structure and the second uneven structure;
a light shielding film provided above the first insulating film and above the trench;
The photodetector, wherein the first insulating film contains hafnium oxide. The first uneven structure and the second uneven structure have recesses,
The photodetector according to claim 1, wherein a side surface of the recess on the first side and a side surface of the trench on the first side are non-parallel in a cross-sectional view. The light shielding film is provided above the substrate,
2. 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 a cross-sectional view. 4. The photodetector according to claim 3, further comprising a second insulating film provided above the first insulating film and in contact with a 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. 6. The photodetector according to claim 4, 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 metal. The photodetector according to claim 1, wherein the light shielding film is aluminum. The photodetector according to claim 1, wherein a side surface of the trench has a tapered shape in a cross-sectional view. The photodetector according to claim 9, wherein the taper shape is a forward taper within a range of 0 to 30 degrees. a first pixel having the first photoelectric conversion region and the first uneven structure;
2. The photodetector according to claim 1, further comprising: a second pixel having said second photoelectric conversion region and said second concave-convex structure. 12. The photodetector according to claim 11, wherein a light shielding material having a light shielding property for optically separating the first pixel and the second pixel is embedded in at least part of the trench. The photodetector according to claim 1, wherein at least part of the trench is filled with metal. The first uneven structure or the second uneven structure scatters light,
2. The photodetector of claim 1, wherein the trench reflects the light. The first pixel has a first color filter above the first concave-convex structure,
The photodetector according to claim 11, wherein the second pixel has a second color filter above the second concave-convex structure. The first uneven structure has two or more recesses,
The photodetector according to claim 15, wherein the second concave-convex structure has two or more concave portions. The photodetector according to claim 15, wherein the width of the first concave-convex structure is approximately 80% of the width of the first color filter in a cross-sectional view. the first color filter corresponds to a first color;
the second color filter corresponds to a second color;
17. The pitch of the recesses of the first uneven structure below the first color filter and the pitch of the recesses of the second uneven structure below the second color filter are the same. photodetector. the first color filter corresponds to a first color;
the second color filter corresponds to a second color;
17. The method according to claim 16, wherein the number of concave portions of the first concave-convex structure below the first color filter is the same as the number of concave portions of the second concave-convex structure below the second color filter. photodetector. the first color filter corresponds to a first color;
the second color filter corresponds to a second color;
17. The method according to claim 16, wherein the depth of the concave portion of the first concave-convex structure below the first color filter and the depth of the concave portion of the second concave-convex structure below the second color filter are the same. photodetector. After forming an uneven structure on the substrate surface above the first photoelectric conversion region and the second photoelectric conversion region provided on the substrate,
forming a trench having a depth longer than a width in the substrate between the first photoelectric conversion region and the second photoelectric conversion region;
forming a first insulating film containing hafnium oxide above the uneven structure so as to be provided in at least a portion of the trench;
A method of manufacturing a photodetector, wherein a light shielding film is formed above the first insulating film and above the trench. After forming a trench having a depth longer than a width in the substrate between a first photoelectric conversion region and a second photoelectric conversion region provided in the substrate,
forming an uneven structure on the substrate surface above the first photoelectric conversion region and the second photoelectric conversion region;
forming a first insulating film containing hafnium oxide above the uneven structure so as to be provided in at least a portion of the trench;
A method of manufacturing a photodetector, wherein a light shielding film is formed above the first insulating film and above the trench. The uneven structure is formed by wet etching,
23. The method of manufacturing a photodetector according to claim 21, wherein the trench is formed by dry etching.

Images