WO2023085147A1

WO2023085147A1 - Solid-state imaging device

Info

Publication number: WO2023085147A1
Application number: PCT/JP2022/040639
Authority: WO
Inventors: 元昭中村
Original assignee: ソニーセミコンダクタソリューションズ株式会社
Priority date: 2021-11-12
Filing date: 2022-10-31
Publication date: 2023-05-19
Also published as: JP2023072323A

Abstract

The main purpose of the present invention is to provide a solid-state imaging device having a novel structure for reducing reflection of incident light.　The present technology provides a solid-state imaging device comprising: a semiconductor substrate having a first surface that is a light incident surface, and a second surface opposing the first surface; and two or more pixels including the semiconductor substrate. The semiconductor substrate includes, in one or more of the pixels, a first porous region formed on the first surface, and a non-porous region formed on the second surface side of the first porous region.

Description

Solid-state imaging device

This technology relates to solid-state imaging devices.

In a solid-state imaging device, a so-called moth-eye structure has been proposed as a structure for reducing the reflection of incident light, in which a fine uneven structure is provided on the interface on the light incident surface side of a semiconductor substrate on which a photoelectric conversion element is formed ( For example, Patent Document 1 below).

JP 2020-61576 A

In recent years, the number of pixels in solid-state imaging devices has been increasing, and the size of one pixel tends to be reduced. If the size of one pixel is further reduced in the future, there is a possibility that the effect of reducing the reflection of incident light in the moth-eye structure will not be sufficiently exhibited.

Therefore, the main purpose of the present technology is to provide a solid-state imaging device having a novel structure for reducing reflection of incident light.

This technology
a semiconductor substrate having a first surface that is a light incident surface and a second surface that faces the first surface;
and two or more pixels including the semiconductor substrate,
The semiconductor substrate includes, within one or more pixels, a first porous region formed on the first surface, and a non-porous region formed on the second surface side of the first porous region; having
A solid-state imaging device is provided.
The porosity of the first porous region may increase continuously or stepwise from the second surface side toward the first surface side.
The semiconductor substrate may further have a second porous region in one or more of the pixels, and the second porous region may be formed in a direction perpendicular to the first surface of the semiconductor substrate.
The semiconductor substrate may further have a third porous region within one or more of the pixels. The third porous region may be formed on the second surface of the semiconductor substrate.
The third porous region may be formed inside the non-porous region.

It is a figure which shows an example of the whole structure of a solid-state imaging device. It is a figure which shows an example of the cross-sectional structure of a solid-state imaging device. FIG. 3A is a schematic diagram of a semiconductor substrate in a conventional solid-state imaging device. 3B is a schematic diagram of a semiconductor substrate in the solid-state imaging device according to the first embodiment; FIG. FIG. 4A is a schematic diagram showing a first porous region with continuously increasing porosity. FIG. 4B is a schematic diagram showing a first porous region with a stepwise increase in porosity. It is a figure which shows an example of the cross-sectional structure in the manufacturing process of a solid-state imaging device. It is a figure which shows an example of the cross-sectional structure in the manufacturing process of a solid-state imaging device. It is a figure which shows an example of the cross-sectional structure in the manufacturing process of a solid-state imaging device. It is a figure which shows an example of the cross-sectional structure in the manufacturing process of a solid-state imaging device. It is a figure which shows an example of the cross-sectional structure in the manufacturing process of a solid-state imaging device. It is a figure which shows an example of the cross-sectional structure in the manufacturing process of a solid-state imaging device. It is a schematic diagram which shows an example of the cross section of the semiconductor substrate in 2nd Embodiment. It is a schematic diagram which shows an example of the cross section of the semiconductor substrate in 3rd Embodiment. It is a schematic diagram which shows an example of the cross section of the semiconductor substrate in 3rd Embodiment. It is a figure which shows the usage example of the solid-state imaging device of this technique. It is a functional block diagram showing an example of electronic equipment to which a solid-state imaging device of this art is applied. 1 is a diagram showing an example of a schematic configuration of an endoscopic surgery system; FIG. 3 is a block diagram showing an example of functional configurations of a camera head and a CCU; FIG. 1 is a block diagram showing an example of a schematic configuration of a vehicle control system; FIG. FIG. 4 is an explanatory diagram showing an example of installation positions of an outside information detection unit and an imaging unit;

A preferred embodiment for implementing this technology will be described below. It should be noted that the embodiments described below show typical embodiments of the present technology, and the scope of the present technology is not limited only to these embodiments.

Unless otherwise specified, in this specification, "upper" means upward or upward in the figure, "bottom" means downward or downward in the figure, and "left" means It means the left direction or the left side in the drawing, and "right" means the right direction or the right side in the drawing. Also, the same or equivalent elements or members shown in the drawings are denoted by the same reference numerals, and overlapping descriptions are omitted.

The present technology will be described in the following order.
1. First Embodiment 1-1. Overall configuration 1-2. Cross-sectional configuration 1-3. Semiconductor substrate 1-4. Method for manufacturing a solid-state imaging device2. Second Embodiment 3. Third Embodiment 4. Usage example of solid-state imaging device to which this technology is applied5. Example of application to endoscopic surgery system6. Example of application to mobile objects

1. 1st embodiment

1-1. overall structure

An overall configuration example of a solid-state imaging device according to the first embodiment of the present technology will be described with reference to FIG. FIG. 1 is a diagram showing an example of the overall configuration of a solid-state imaging device 1. As shown in FIG. As an example, a case where the solid-state imaging device 1 is a back-illuminated CMOS (Complementary Metal Oxide Semiconductor) solid-state imaging device will be described below. In a back-illuminated CMOS solid-state imaging device, light enters from the back side of a semiconductor substrate on which pixel transistors are formed.

The solid-state imaging device 1 includes, for example, a semiconductor substrate 11, a pixel region 3 having a plurality of pixels 2 arranged on the semiconductor substrate 11, a vertical driving circuit 4, a column signal processing circuit 5, a horizontal driving circuit 6, an output circuit 7, and a control circuit 8 and the like.

The pixel 2 has, for example, a photodiode as a photoelectric conversion element and a plurality of pixel transistors. The plurality of pixel transistors may be, for example, four MOS transistors including a transfer transistor, a reset transistor, a select transistor, and an amplifier transistor.

The pixel region 3 has a plurality of pixels 2 regularly arranged in a two-dimensional array on the semiconductor substrate 11 . The pixel area 3 includes an effective pixel area for amplifying the signal charge generated by photoelectric conversion by actually receiving light and reading it out to the column signal processing circuit 5, and a black area for outputting optical black as a reference of the black level. and a reference pixel region (not shown). The black reference pixel area can usually be formed on the periphery of the effective pixel area.

The control circuit 8 generates a clock signal, a control signal, and the like, which serve as references for the operation of the vertical driving circuit 4, the column signal processing circuit 5, the horizontal driving circuit 6, and the like, based on the vertical synchronizing signal, the horizontal synchronizing signal, and the master clock. Generate. A clock signal, a control signal, and the like generated by the control circuit 8 are input 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. The vertical drive circuit 4 sequentially selectively scans each pixel 2 in the pixel region 3 in units of rows in the vertical direction. Then, the vertical drive circuit 4 supplies pixel signals based on signal charges generated in the photodiode of each pixel 2 according to the amount of light received to the column signal processing circuit 5 through the vertical signal lines 9 .

The column signal processing circuit 5 is arranged for each column of pixels 2, for example. The column signal processing circuit 5 performs signal processing such as noise elimination and signal amplification on the signals output from the pixels 2 of one row for each pixel column. Such signal processing may be performed, for example, using signals from a black reference pixel region (not shown).

The horizontal driving circuit 6 is composed of, for example, a shift register. By sequentially outputting horizontal scanning pulses, the horizontal drive circuit 6 sequentially selects each of the column signal processing circuits 5 and outputs pixel signals from each of the column signal processing circuits 5 to the horizontal signal line 10 .

The output circuit 7 performs signal processing on signals sequentially supplied from each of the column signal processing circuits 5 through the horizontal signal line 10, and outputs the processed signals.

1-2. cross section

A cross-sectional configuration example of the solid-state imaging device 1 will be described with reference to FIG. FIG. 2 is a diagram showing an example of a cross-sectional configuration of the solid-state imaging device 1. As shown in FIG. In FIG. 2 , the upper side is the back side of the solid-state imaging device 1 and the lower side is the front side of the solid-state imaging device 1 .

The solid-state imaging device 1 includes, for example, a semiconductor substrate 11, a multilayer wiring layer 21, a support substrate 31, a transparent insulating film 41, and an on-chip lens 51. Moreover, the solid-state imaging device 1 includes two or more pixels 2 . The pixel 2 includes, for example, a semiconductor substrate 11, a photodiode (not shown) provided in the semiconductor substrate 11, a multilayer wiring layer 21, a support substrate 31, a transparent insulating film 41, an on-chip lens 51, and the like. be done.

The semiconductor substrate 11 has a first surface 11a, which is a light incident surface, and a second surface 11b facing the first surface 11a. In the solid-state imaging device 1, the first surface 11a of the semiconductor substrate 11 is the back surface, and the second surface 11b of the semiconductor substrate 11 is the front surface.

The semiconductor substrate 11 is made of, for example, silicon (Si) (especially single crystal silicon). The thickness of the semiconductor substrate may be, for example, 1 μm to 6 μm. A photodiode (not shown) is provided for each pixel 2 in the semiconductor substrate 11 . A photodiode is an example of a photoelectric conversion element.

The semiconductor substrate 11 has, in one or more pixels 2, a first porous region 12 formed on the first surface 11a and a non-porous region 13 formed on the second surface 11b side of the first porous region 12. and have The first porous region 12 is a region provided to reduce reflection of incident light on the semiconductor substrate 11 . Details of the first porous region 12 and the non-porous region 13 will be described later.

The semiconductor substrate 11 may have pixel isolation portions 14 between adjacent pixels 2 . The pixel separation section 14 includes an insulating film. Adjacent pixels 2, ie, adjacent photodiodes are thereby electrically isolated. Viewing the structure of the semiconductor substrate 11 shown in FIG. 2 from the side of the first surface 11a, the pixel separation section 14 may be formed in a grid pattern so as to separate adjacent pixels 2, for example. A photodiode can be formed in a region separated by the pixel isolation portion 14 .

The multilayer wiring layer 21 is formed on the second surface 11b side of the semiconductor substrate 11 (the surface side, that is, the lower side). The multilayer wiring layer 21 has a plurality of wiring layers 22 and an interlayer insulating film 23 . Furthermore, the multilayer wiring layer 21 has a plurality of pixel transistors for reading out electric charges accumulated in the photodiodes. The pixel transistor has a gate electrode 24 . In FIG. 2, the presence of the pixel transistor is indicated by showing the gate electrode 24. As shown in FIG.

The support substrate 31 is formed on the front side (lower side) of the multilayer wiring layer 21 . The support substrate 31 is made of silicon (Si), for example. The thickness of the support substrate 31 is not particularly limited, and may be several hundred μm, for example.

The transparent insulating film 41 is formed on the side of the first surface 11a of the semiconductor substrate 11 (the back side, that is, the upper side). The transparent insulating film 41 transmits light and has insulating properties. The transparent insulating film 41 may be formed using one or more materials selected from, for example, silicon oxide, silicon nitride, silicon oxynitride, and hafnium oxide (HfO ₂ ).

The on-chip lens 51 is formed on the back side (upper side) of the transparent insulating film 41 . The on-chip lens 51 can be made of, for example, a resin material such as styrene resin, acrylic resin, styrene-acrylic copolymer resin, and siloxane resin. An on-chip lens 51 collects the incident light. The collected light is efficiently incident on the photodiode.

1-3. semiconductor substrate

The semiconductor substrate 11 will be described with continued reference to FIG.

The semiconductor substrate 11 has a first porous region 12 formed on the first surface 11a within one or more pixels 2 . The first porous region 12 includes a first surface 11a. That is, the back surface (upper surface) of the first porous region 12 is the first surface 11a.

The first porous region 12 is a region having many pores. If the semiconductor substrate 11 is made of silicon (especially monocrystalline silicon), the first porous region 12 may be made of porous silicon, for example.

The semiconductor substrate 11 further has a non-porous region 13 formed on the second surface 11b side of the first porous region 12 in one or more pixels 2 . The non-porous region 13 shown in FIG. 2 includes the second surface 11b. That is, in FIG. 2, the front surface (lower surface) of the non-porous region 13 is the second surface 11b. However, the non-porous region 13 only needs to be located closer to the second surface 11b (below the first porous region 12) than the first porous region 12 in the semiconductor substrate 11. may be configured without That is, the semiconductor substrate 11 may further have another region formed on the second surface side of the non-porous region 13 . The other region may be, for example, a third porous region which will be described later.

The non-porous region 13 is a region that does not have pores. The non-porous region 13 may be made of bulk silicon, for example.

The first porous region 12 and the non-porous region 13 have different refractive indices. Specifically, the refractive index of the first porous region is lower than that of the non-porous region 13 due to the presence of numerous pores. By forming the region having a smaller refractive index than the non-porous region 13 on the first surface 11a (light incident surface) of the semiconductor substrate 11, reflection of incident light on the semiconductor substrate 11 can be reduced.

With reference to FIG. 3, the effect of reducing the reflection of incident light by the first porous region 12 of the semiconductor substrate 11 will be described in comparison with the semiconductor substrate in the conventional solid-state imaging device. FIG. 3A is a schematic diagram of a semiconductor substrate 91 in a conventional solid-state imaging device. FIG. 3B is a schematic diagram of the semiconductor substrate 11 in the solid-state imaging device according to this embodiment. In FIG. 3, the upper side is the back side of the semiconductor substrate, and the lower side is the front side of the semiconductor substrate.

The semiconductor substrate 91 in the prior art shown in FIG. 3A is made of non-porous material and has no porous regions. Incident light L91 travels from the member 90 with a low refractive index toward the semiconductor substrate 91 with a high refractive index. Since the member 90 and the semiconductor substrate 91 have different refractive indexes, part of the incident light L91 is reflected at the interface between the member 90 and the semiconductor substrate 91 to generate reflected light L92. In the conventional solid-state imaging device, the difference in refractive index between the member 90 and the semiconductor substrate 91 is large, so the reflected light L92 tends to be large.

It can be understood from the following formula (1) for calculating the magnitude (intensity) of reflected light that the greater the difference in refractive index, the greater the reflected light. The following formula (1) is a formula for calculating the magnitude (intensity) of reflected light generated at the interface between two substances of different types (substance 1 and substance 2).

(In the above formula (1), I is the magnitude (intensity) of reflected light, _I0 is the magnitude (intensity) of incident light, _n1 is the refractive index of substance 1, and n2 is the refractive index of substance 2. )

From the above formula (1), the larger the value of “n ₁ −n ₂ ”, that is, the larger the difference between the refractive index n ₁ of the substance 1 and the refractive index n ₂ of the substance 2, the greater the magnitude of the reflected light ( intensity) I increases.

On the other hand, the semiconductor substrate 11 in this embodiment shown in FIG. 3B has a first porous region 12 and a non-porous region 13 . A member having a small refractive index (for example, a transparent insulating film 41) is provided on the first surface 11a side (light incident surface side) of the semiconductor substrate 11 . In FIG. 4B, the transparent insulating film 41 has the lowest refractive index (refractive index: small), the first porous region 12 has the next lowest refractive index (refractive index: medium), and the non-porous region 13 has the highest refractive index (refractive index: large). Incident light L1 travels from the transparent insulating film 41 having the lowest refractive index to the first porous region 12 having a medium refractive index and the non-porous region 13 having the highest refractive index. Part of the incident light L1 is reflected at the interface between the transparent insulating film 41 and the first porous region 12 to generate reflected light L2. The difference in refractive index between the transparent insulating film 41 and the first porous region 12 is smaller than the difference in refractive index between the member 90 and the semiconductor substrate 91 in the prior art (FIG. 3A). Therefore, the intensity of the reflected light L2 is lower than the intensity of the reflected light L92 in the prior art. As described above, in this embodiment, the presence of the first porous region 12 makes it possible to reduce the reflection of incident light.

Another part of the incident light L1 is reflected at the interface between the first porous region 12 and the non-porous region 13 to generate reflected light L3. In order to reduce the reflected light L3, that is, to further reduce the reflection of the incident light on the semiconductor substrate 11, the thickness d of the first porous region 12 preferably satisfies the following formula (2). sell.

d=λ/4n (2)
(In the above formula (2), d is the thickness of the first porous region, λ is the wavelength of incident light, and n is the refractive index of the first porous region.)

When the thickness d of the first porous region 12 satisfies the above formula (2), the magnitude (intensity) of the reflected light L3 at the interface between the first porous region 12 and the non-porous region 13 is can be minimized by the interference effects of By adjusting the thickness of the first porous region 12 in this manner, the effect of reducing the reflection of incident light by the first porous region 12 can be further enhanced.

In addition, in the semiconductor substrate 11 shown in FIG. 3B, an interface exists between the first porous region 12 and the non-porous region 13, but in the semiconductor substrate 11, a configuration in which the interface does not exist is also adopted. can be In the case of this configuration, since the occurrence of reflected light itself is prevented, the effect of reducing the reflection of incident light can be further enhanced. The details of the configuration in which the interface does not exist will be described later.

　In the first porous region 12, the refractive index correlates with the porosity. Specifically, the higher the porosity, the lower the refractive index.

The porosity is the ratio of voids (pores) in the first porous region 12, specifically, the void fraction per unit volume in the first porous region 12. Porosity can be measured, for example, by Gravimetry, Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), and X-Ray Reflectivity (XRR). (Reference: Leigh Canham, "Handbook of porous silicon", Second edition, P. 157).

The upper limit of porosity is preferably 90% or less, more preferably 70% or less, even more preferably 60% or less, and particularly preferably 50% or less. The lower limit of porosity is preferably 10% or more, more preferably 20% or more, even more preferably 30% or more, and particularly preferably 40% or more. The numerical range of the porosity may be, for example, a combination selected from the upper limit value and the lower limit value described above, preferably 10% or more and 90% or less, more preferably 20% or more and 90% or less, still more preferably 30% or more and 70% or less, particularly preferably 30% or more and 60% or less or 40% or more and 50% or less.

As mentioned above, the first porous region 12 may be made of porous silicon and the non-porous region 13 may be made of bulk silicon. Porous silicon can have, for example, the following porosities and refractive indices:
<Refractive index of porous silicon>
30% porosity: about 2.3
Porosity 45%: about 1.8
Porosity 60%: about 1.5
Porosity 75%: about 1.3
The refractive index of bulk silicon can be, for example, about 4.0. The refractive index of air is 1.0. The refractive index of porous silicon with a porosity of 30% (approximately 2.3) can be said to be approximately halfway between the refractive indices of bulk silicon and air. Thus, for example, when the first porous region 12 is porous silicon and the non-porous region 13 is bulk silicon, a porosity of 30% or more may be selected for the porous silicon.

The porosity of the first porous region 12 may be uniform or non-uniform. If the porosity is non-uniform in the first porous region 12, the porosity preferably increases continuously or stepwise from the second surface 11b side of the semiconductor substrate 11 toward the first surface 11a side. ing. By "continuous" is meant a seamless change in porosity. By "gradual" is meant that there is a seam in the change in porosity. Such a continuous or stepwise increase in porosity can improve the effect of reducing reflection of incident light on the semiconductor substrate 11 . This is because the change in the refractive index in the semiconductor substrate 11 becomes smaller, and the intensity of the reflected light can be further reduced. If the porosity is non-uniform in the first porous region 12, it is preferred that the minimum and maximum porosity values fall within the numerical ranges for porosity described above.

A change in the porosity of the first porous region 12 will be described with reference to FIG. FIG. 4A is a schematic diagram showing a first porous region 12A with continuously increasing porosity. FIG. 4B is a schematic diagram showing a first porous region 12B with a stepwise increase in porosity. In FIG. 4, the upper side is the back side of the semiconductor substrate, and the lower side is the front side of the semiconductor substrate. In the first porous region 12A (FIG. 4A) and the first porous region 12B (FIG. 4B), the difference in porosity is indicated by the shades of color. A lighter color indicates greater porosity and more voids, and a darker color indicates smaller porosity and fewer voids. Non-porous regions 13A (FIG. 4A) and non-porous regions 13B (FIG. 4B) do not have voids and are therefore shown in the darkest color.

The porosity of the first porous region 12A shown in FIG. 4A increases continuously from the second surface 11Ab side of the semiconductor substrate 11A toward the first surface 11Aa side. That is, the porosity varies seamlessly.

The first porous region 12B shown in FIG. 4B is formed by stacking three

porous layers

121, 122, 123 each having a certain degree of porosity. The porosity increases in order of the porous layer 123, the porous layer 122, and the porous layer 121. FIG. A porous layer 123, a porous layer 122, and a porous layer 121 are laminated in this order from the second surface 11Bb side of the semiconductor substrate 11B toward the first surface 11Ba side. Accordingly, the porosity of the first porous region 12B increases stepwise from the second surface 11Bb side of the semiconductor substrate 11B toward the first surface 11Ba side. The interface between the non-porous region 13B and the porous layer 123, the interface between the porous layer 123 and the porous layer 122, and the interface between the porous layer 122 and the porous layer 121 correspond to the seams where the porosity changes. do.

In this embodiment, the porosity preferably increases continuously from the second surface 11Ab side of the semiconductor substrate 11A toward the first surface 11Aa side, as shown in FIG. 4A. The first porous region 12A does not have an interface (surface where members having different porosities are in contact with each other) within the semiconductor substrate 11A. Since there is no interface that causes the generation of reflected light, the generation of incident light itself can be prevented. That is, the effect of reducing reflection of incident light can be further improved.

The semiconductor substrate 11 used in this embodiment is not limited to the configuration shown in FIGS. 4A and 4B. Semiconductor substrate 11 may, for example, be configured by combining the elements shown in FIGS. 4A and 4B. The semiconductor substrate 11 may have, for example, a structure in which the first porous region 12A shown in FIG. 4A is laminated on the non-porous region 13B shown in FIG. 4B. That is, the structure in which the first porous region 12 having the porosity continuously increasing from the second surface 11b side to the first surface 11a side is laminated on the first surface 11a side of the non-porous region 13. may be

Refer to Figure 2 again. The solid-state imaging device 1 of this embodiment shown in FIG. 2 includes a semiconductor substrate 11 having a first porous region 12 . Thereby, the solid-state imaging device 1 can reduce the reflection of incident light.

In addition, the configuration having the first porous region 12 can suppress the diffraction of light compared to the moth-eye structure described in Patent Document 1, for example. Generally, in a solid-state imaging device, crosstalk (color mixture) may occur when diffracted light leaks into adjacent pixels. The solid-state imaging device 1 of this embodiment can also suppress the occurrence of crosstalk (color mixture) by suppressing diffraction.

Next, a method for forming the first porous region 12 will be described. Specifically, the first porous region 12 is formed by porosifying a non-porous material. Therefore, hereinafter, a method for making a non-porous material porous will be described with an example. In this example, the non-porous material is a silicon substrate made of single crystal silicon, and the resulting porous material is porous silicon.

The silicon substrate is made porous by an anodizing method. This forms porous silicon. The anodizing method is a method of making porous by subjecting single crystal silicon to anodizing treatment (anodizing treatment) in a hydrogen fluoride (HF) solution.

The porosity of porous silicon can be adjusted, for example, by the HF concentration in the anodizing treatment. Specifically, lowering the HF concentration lowers the density of pores, resulting in lower porosity. For example, by controlling the HF concentration within the range of 20 mass % to 50 mass %, the pore density can be within the range of 0.6 g/cm ³ to 1.1 g/cm ³ .

Also, the porosity of the porous silicon can be adjusted, for example, by the current density in the anodizing treatment. Specifically, increasing the current density increases the diameter of the pores in the porous silicon, resulting in increased porosity. For example, at high current densities (eg, 100 mA/cm ² ), the pore diameter can be in the range of 10 nm to 60 nm, and at low current densities, the pore diameter can be several nm. .

The porosity of porous silicon may be adjusted by HF concentration alone, current density alone, or a combination of HF concentration and current density. That is, the porosity of porous silicon may be adjusted by HF concentration and/or current density.

Next, a method for manufacturing the semiconductor substrate 11 will be described. Also in the description, a silicon substrate and porous silicon are taken as examples. Examples of the method for manufacturing the semiconductor substrate 11 can be broadly classified into two. A method of making a portion of a silicon substrate porous, and a method of combining a silicon substrate and porous silicon.

First, the method of making part of the silicon substrate porous is, specifically, a method of forming porous silicon on one surface of the silicon substrate and its vicinity by the above-described anodization method. The porous silicon corresponds to the first porous region 12 in this embodiment, and the non-porous portion corresponds to the non-porous region 13 in this embodiment.

In this method, the porosity of the porous silicon can be varied continuously by varying the HF concentration and/or current density during the anodizing treatment. For example, increasing the HF concentration and/or increasing the current density during the anodizing process can continuously increase the porosity towards one surface of the silicon substrate. More specifically, for example, in the anodizing treatment, first, a region with small porosity (a region with a pore diameter of several nm) is formed at a low current density, and then at a high current density (eg, 100 mA/cm ² ). A region of high porosity (region with pore diameters of 10 nm to 60 nm) can be formed. As a result, for example, a first porous region 12A can be formed in which the porosity increases continuously from the second surface 11Ab side toward the first surface 11Aa side, as shown in FIG. 4A.

Next, the method of combining a silicon substrate and porous silicon is, specifically, to form a porous layer made of porous silicon by the above-described anodizing method, and one or more of the porous layers are formed on a silicon substrate. It is a method of laminating on one side surface of One or more porous layers correspond to the first porous region 12 in this embodiment, and the silicon substrate corresponds to the non-porous region 13 in this embodiment.

A plurality of porous layers may have different porosities. The plurality of porous layers preferably have porosities different from each other, and are stacked on one side surface of the silicon substrate in order of decreasing porosity. As a result, a first porous region 12B can be formed in which the porosity increases stepwise from the second surface 11Bb side to the first surface 11Ba side, for example, as shown in FIG. 4B.

Although the two methods for manufacturing the semiconductor substrate 11 have been described above as examples, these two methods may be used in combination. For example, a porous layer made of porous silicon with continuously increasing porosity may be formed, and the porous layer may be stacked on one side surface of the silicon substrate. As a result, semiconductor substrate 11 having a configuration in which first porous region 12A shown in FIG. 4A is laminated on non-porous region 13B shown in FIG. 4B is obtained.

1-4. Manufacturing method of solid-state imaging device

An example of a method for manufacturing the solid-state imaging device 1 shown in FIG. 2 will be described with reference to FIGS. 5 to 10 are diagrams showing an example of a cross-sectional configuration in each manufacturing process of the solid-state imaging device 1. FIG. In the following description, a manufacturing method using a silicon substrate is taken as an example. 5 to 7, the upper side is the front side of the solid-state imaging device 1, and the lower side is the rear side of the solid-state imaging device 1. FIG. 8 to 10, the upper side is the back side of the solid-state imaging device 1, and the lower side is the front side of the solid-state imaging device 1. FIG.

First, a p-type impurity layer 52, which is a high-concentration p-type impurity layer, is formed in a first silicon substrate 51 by ion implantation (FIG. 5). In the p-type impurity layer 52, the impurity concentration is preferably 1.0×10 ¹⁸ /cm ³ or higher.

The impurity layer of the pixel is formed by ion implantation. A pixel isolation portion 14 is formed between adjacent pixels. Furthermore, a multilayer wiring layer 21 having a wiring layer 22, an interlayer insulating film 23, and a gate electrode 24 is formed. As a result, a multilayer wiring layer 21 is laminated on the front side of the semiconductor substrate 11 having the pixel separation section 14 (FIG. 6).

A support substrate 31 is laminated on the front side of the multilayer wiring layer 21 (FIG. 7). Next, the substrate is turned upside down so that the first silicon substrate 51 located at the bottom layer in FIG. 7 is located at the top layer. The first silicon substrate 51 located on the uppermost layer is etched to expose the p-type impurity layer 52 (FIG. 8).

The p-type impurity layer 52 is made porous by an anodizing method to form the first porous region 12 (FIG. 9). The front side of the first porous region 12 becomes the non-porous region 13 . The method of making the substrate porous by anodization can be, for example, as described in the above “1-3. Semiconductor substrate”.

The surface of the first porous region 12 is etched (Fig. 10). After that, a transparent insulating film 41 and an on-chip lens 51 are formed in this order on the back side of the first porous region 12 (FIG. 2).

The manufacturing method of the solid-state imaging device 1 described above is an example, and is not limited to this. For example, the first silicon substrate 51 may be etched to make the p-type impurity layer 52 porous before laminating the support substrate 31 on the back side of the multilayer wiring layer 21 .

2. Second embodiment

A solid-state imaging device according to a second embodiment of the present technology will be described with reference to FIG. FIG. 11 is a schematic diagram showing an example of a cross section of a semiconductor substrate 11C in the second embodiment. In FIG. 11, only a part of one pixel 2 is extracted and description of other adjacent pixels is omitted. Also, in FIG. 11, the upper side is the back side of the semiconductor substrate 11C, and the lower side is the front side of the semiconductor substrate 11C.

The semiconductor substrate 11C has the first porous region 12 and the non-porous region 13, the pixel separating portion 14 as necessary, and the second porous region 61 in one or more pixels 2. The second porous region 61 is formed perpendicular to the first surface 11Ca of the semiconductor substrate 11C. The second porous region 61 shown in FIG. 11 extends from the first surface 11Ca of the semiconductor substrate 11C to the second surface 11Cb, but the shape of the second porous region 61 is not limited to this. The second porous region 61 has, for example, a shape extending from the first surface 11Ca to the middle of the non-porous region 13, or a shape extending from the second surface 11Cb to the middle of the non-porous region 13. A shape, or a shape located in the middle of the non-porous region 13 away from the first surface 11Ca and the second surface 11Cb may be used.

As shown in FIG. 11, the second porous region 61 is preferably formed outside and adjacent to the non-porous region 13 within one or more pixels 2 . Further, the second porous region 61 is more preferably formed adjacent to the outside of the non-porous region 13 and the inside of the pixel separating portion 14 in one or more pixels 2, that is, the one or more pixels 2 is formed between the non-porous region 13 and the pixel separating portion 14 . Although two second porous regions 61 are shown in one pixel 2 in FIG. 11, the number of second porous regions 61 in one pixel 2 may be one or more. you can

The second porous region 61, like the first porous region 12, has a large number of pores. When the semiconductor substrate 11C is made of silicon (especially single crystal silicon), the second porous region 61 may be made of porous silicon, for example.

The refractive index of the second porous region 61 is small due to the presence of many pores. Therefore, the difference in refractive index between the non-porous region 13 and the second porous region 61 is greater than the difference in refractive index between the non-porous region 13 and the pixel separating portion 14 . As described above, the greater the difference in refractive index, the greater the reflected light. Therefore, the second porous region 61 can increase the reflected light L5 of the incident light L4, thereby efficiently concentrating the light toward the inside of the pixel 2 .

3. Third embodiment

A solid-state imaging device according to a third embodiment of the present technology will be described with reference to FIGS. 12 and 13 are schematic diagrams showing an example of the cross section of the semiconductor substrate 11D in the third embodiment. In FIGS. 12 and 13, only a part of one pixel 2 is extracted and the description of other adjacent pixels is omitted. 12 and 13, the upper side is the back side of the semiconductor substrate 11D, and the lower side is the front side of the semiconductor substrate 11D.

A semiconductor substrate 11D shown in FIG. 12 has a first porous region 12 and a non-porous region 13, a pixel separating portion 14 as necessary, and a third porous region 71 in one or more pixels 2. The third porous region 71 shown in FIG. 12 is formed on the second surface 11Db of the semiconductor substrate 11D. The third porous region 71 is configured including the second surface 11Db. That is, the front side surface (lower side surface) of the third porous region 71 is the second surface 11Db.

The third porous region 71, like the first porous region 12, has a large number of pores. When the semiconductor substrate 11D is made of silicon, the third porous region 71 may be made of porous silicon, for example.

The third porous region 71 reflects incident light L6 that has reached the front surface (lower surface) of the non-porous region 13 to generate reflected light L7. In this way, the third porous region 71 can suppress the incident light L6 from escaping from the front side of the non-porous region 13, thereby efficiently concentrating the light toward the inside of the pixel 2. FIG.

A third porous region 71 shown in FIG. 13 is formed inside the non-porous region 13 . That is, the third porous region 71 shown in FIG. 13 is surrounded by the non-porous region 13 . By reflecting more incident light inside the semiconductor substrate 11</b>D, more light stays inside the pixel 2 and the light utilization efficiency can be improved.

A third porous region 71 shown in FIGS. 13A to 13C has, for example, a rectangular parallelepiped shape inside the pixel 2 . The third porous region 71 in FIG. 13A is formed at a position spaced apart from the center of the non-porous region 13 toward the rear side (upper side). A third porous region 71 in FIG. 13B is formed near the center of the non-porous region 13 . The third porous region 71 in FIG. 13C is formed at a position spaced from the center of the non-porous region 13 toward the front side (lower side).

The third porous region 71 shown in FIG. 13D has a box shape with an opening on the back side (upper side) inside the pixel 2 and is formed near the center of the non-porous region 13 . The third porous region 71 shown in FIG. 13E has a box shape with an opening on the front side (lower side) inside the pixel 2 and is formed near the center of the non-porous region 13 .

The number of third porous regions 71 may be one or more in one pixel 2 . When a plurality of third porous regions 71 are formed in one pixel 2, the plurality of third porous regions 71 are selected from the third porous regions 71 shown in FIGS. 12 and 13A to 13E. It may be a combination of two or more. Thus, the third porous regions 71 shown in Figures 12 and 13A-13E may be combined unless technical conflicts arise.

The configuration of the third embodiment described above may be combined with the configuration of the second embodiment as long as there is no technical contradiction. That is, in the solid-state imaging device 1 , the semiconductor substrate 11 includes one or more second porous regions 61 and one or more third porous regions 71 in addition to the first porous region 12 and the non-porous region 13 . may further have

As described above, the solid-state imaging device of the present technology has been described using the backside illumination type as an example, but the solid-state imaging device of the present technology may be a front side illumination type. Even in the case of the front illumination type, the reflection of incident light can be reduced by providing the configuration of the present technology.

4. Usage example of a solid-state imaging device to which this technology is applied

FIG. 14 is a diagram showing a usage example of the solid-state imaging device of the present technology.

The solid-state imaging device of this technology can be used in various cases for sensing light such as visible light, infrared light, ultraviolet light, and X-rays. That is, as shown in FIG. 14, for example, the field of appreciation for photographing images to be used for viewing, the field of transportation, the field of home appliances, the field of medicine/healthcare, the field of security, the field of beauty, the field of sports, and the like. The solid-state imaging device of the present technology can be used for devices used in the fields of agriculture, agriculture, and the like.

Specifically, in the field of viewing, for example, the solid-state imaging device of this technology is used in devices for capturing images for viewing, such as digital cameras, smartphones, and mobile phones with camera functions. can be used.

In the field of transportation, for example, in-vehicle sensors that capture images of the front, back, surroundings, and interior of a vehicle, and monitor running vehicles and roads for safe driving such as automatic stopping and recognition of the driver's condition. The solid-state imaging device of the present technology can be used for devices used for transportation, such as surveillance cameras that monitor traffic, distance sensors that measure distances between vehicles, and the like.

In the field of home appliances, for example, the present technology can be applied to devices used in home appliances, such as television receivers, refrigerators, and air conditioners, in order to photograph user gestures and perform device operations according to the gestures. A solid-state imager can be used.

In the field of medicine and healthcare, the solid-state imaging device of this technology can be used in medical and healthcare devices such as endoscopes and devices that perform angiography by receiving infrared light. can be used.

In the field of security, the solid-state imaging device of the present technology can be used for devices used for security, such as surveillance cameras for crime prevention and cameras for person authentication.

In the field of beauty, for example, the solid-state imaging device of this technology can be used in devices used for beauty, such as skin measuring instruments that photograph the skin and microscopes that photograph the scalp.

In the field of sports, for example, the solid-state imaging device of this technology can be used in devices used for sports, such as action cameras and wearable cameras for sports.

In the field of agriculture, the solid-state imaging device of this technology can be used for equipment used in agriculture, such as cameras for monitoring the condition of fields and crops.

Next, a specific example of using the solid-state imaging device of this technology will be described. The solid-state imaging device of the present technology can be applied to all types of electronic devices having imaging functions, such as camera systems such as digital still cameras and video cameras, and mobile phones having imaging functions. FIG. 15 shows a schematic configuration of an electronic device 102 (camera) as an example. The electronic device 102 is, for example, a video camera capable of capturing still images or moving images, and includes a solid-state imaging device 101, an optical system (optical lens) 310, a shutter device 311, and the solid-state imaging device 101 and the shutter device 311. It has a drive unit 313 for driving and a signal processing unit 312 .

The optical system 310 guides image light (incident light) from a subject to the pixel portion of the solid-state imaging device 101 . This optical system 310 may be composed of a plurality of optical lenses. The shutter device 311 controls a light irradiation period and a light shielding period for the solid-state imaging device 101 . The drive unit 313 controls the transfer operation of the solid-state imaging device 101 and the shutter operation of the shutter device 311 . The signal processing unit 312 performs various signal processing on the signal output from the solid-state imaging device 101 . The video signal Dout after signal processing is stored in a storage medium such as a memory, or output to a monitor or the like.

5. Example of application to an endoscopic surgery system

This technology can be applied to various products. For example, the technology may be applied to an endoscopic surgical system.

FIG. 16 is a diagram showing an example of a schematic configuration of an endoscopic surgery system to which the technology (this technology) according to the present disclosure can be applied.

FIG. 16 illustrates a state in which an operator (doctor) 11131 is performing surgery on a patient 11132 on a patient bed 11133 using an endoscopic surgery system 11000 . As illustrated, an endoscopic surgery system 11000 includes an endoscope 11100, other surgical instruments 11110 such as a pneumoperitoneum tube 11111 and an energy treatment instrument 11112, and a support arm device 11120 for supporting the endoscope 11100. , and a cart 11200 loaded with various devices for endoscopic surgery.

An endoscope 11100 is composed of a lens barrel 11101 whose distal end is inserted into the body cavity of a patient 11132 and a camera head 11102 connected to the proximal end of the lens barrel 11101 . In the illustrated example, an endoscope 11100 configured as a so-called rigid scope having a rigid lens barrel 11101 is illustrated, but the endoscope 11100 may be configured as a so-called flexible scope having a flexible lens barrel. good.

The tip of the lens barrel 11101 is provided with an opening into which the objective lens is fitted. A light source device 11203 is connected to the endoscope 11100, and light generated by the light source device 11203 is guided to the tip of the lens barrel 11101 by a light guide extending inside the lens barrel 11101, where it reaches the objective. Through the lens, the light is irradiated toward the observation object inside the body cavity of the patient 11132 . Note that the endoscope 11100 may be a straight scope, a perspective scope, or a side scope.

An optical system and an imaging element are provided inside the camera head 11102, and the reflected light (observation light) from the observation target is focused on the imaging element by the optical system. The imaging device photoelectrically converts the observation light to generate an electrical signal corresponding to the observation light, that is, an image signal corresponding to the observation image. The image signal is transmitted to a camera control unit (CCU: Camera Control Unit) 11201 as RAW data.

The CCU 11201 is composed of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and controls the operations of the endoscope 11100 and the display device 11202 in an integrated manner. Further, the CCU 11201 receives an image signal from the camera head 11102 and performs various image processing such as development processing (demosaicing) for displaying an image based on the image signal.

The display device 11202 displays an image based on an image signal subjected to image processing by the CCU 11201 under the control of the CCU 11201 .

The light source device 11203 is composed of a light source such as an LED (light emitting diode), for example, and supplies the endoscope 11100 with irradiation light for imaging a surgical site or the like.

The input device 11204 is an input interface for the endoscopic surgery system 11000. The user can input various information and instructions to the endoscopic surgery system 11000 via the input device 11204 . For example, the user inputs an instruction or the like to change the imaging conditions (type of irradiation light, magnification, focal length, etc.) by the endoscope 11100 .

The treatment instrument control device 11205 controls driving of the energy treatment instrument 11112 for tissue cauterization, incision, blood vessel sealing, or the like. The pneumoperitoneum device 11206 inflates the body cavity of the patient 11132 for the purpose of securing the visual field of the endoscope 11100 and securing the operator's working space, and injects gas into the body cavity through the pneumoperitoneum tube 11111. send in. The recorder 11207 is a device capable of recording various types of information regarding surgery. The printer 11208 is a device capable of printing various types of information regarding surgery in various formats such as text, images, and graphs.

It should be noted that the light source device 11203 that supplies the endoscope 11100 with irradiation light for photographing the surgical site can be composed of, for example, a white light source composed of an LED, a laser light source, or a combination thereof. When a white light source is configured by a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high accuracy. It can be carried out. Further, in this case, the observation target is irradiated with laser light from each of the RGB laser light sources in a time division manner, and by controlling the drive of the imaging device of the camera head 11102 in synchronization with the irradiation timing, each of RGB can be handled. It is also possible to pick up images by time division. According to this method, a color image can be obtained without providing a color filter in the imaging element.

Further, the driving of the light source device 11203 may be controlled so as to change the intensity of the output light every predetermined time. By controlling the drive of the imaging device of the camera head 11102 in synchronism with the timing of the change in the intensity of the light to obtain an image in a time-division manner and synthesizing the images, a high dynamic A range of images can be generated.

Also, the light source device 11203 may be configured to be able to supply light in a predetermined wavelength band corresponding to special light observation. In special light observation, for example, the wavelength dependence of light absorption in body tissues is used to irradiate a narrower band of light than the irradiation light (i.e., white light) used during normal observation, thereby observing the mucosal surface layer. So-called Narrow Band Imaging, in which a predetermined tissue such as a blood vessel is imaged with high contrast, is performed. Alternatively, in special light observation, fluorescence observation may be performed in which an image is obtained from fluorescence generated by irradiation with excitation light. In fluorescence observation, the body tissue is irradiated with excitation light and the fluorescence from the body tissue is observed (autofluorescence observation), or a reagent such as indocyanine green (ICG) is locally injected into the body tissue and the body tissue is examined. A fluorescence image can be obtained by irradiating excitation light corresponding to the fluorescence wavelength of the reagent. The light source device 11203 can be configured to be able to supply narrowband light and/or excitation light corresponding to such special light observation.

FIG. 17 is a block diagram showing an example of functional configurations of the camera head 11102 and CCU 11201 shown in FIG.

The camera head 11102 has a lens unit 11401, an imaging section 11402, a drive section 11403, a communication section 11404, and a camera head control section 11405. The CCU 11201 has a communication section 11411 , an image processing section 11412 and a control section 11413 . The camera head 11102 and the CCU 11201 are communicably connected to each other via a transmission cable 11400 .

A lens unit 11401 is an optical system provided at a connection with the lens barrel 11101 . Observation light captured from the tip of the lens barrel 11101 is guided to the camera head 11102 and enters the lens unit 11401 . A lens unit 11401 is configured by combining a plurality of lenses including a zoom lens and a focus lens.

The number of imaging elements constituting the imaging unit 11402 may be one (so-called single-plate type) or plural (so-called multi-plate type). When the image pickup unit 11402 is configured as a multi-plate type, for example, image signals corresponding to RGB may be generated by each image pickup element, and a color image may be obtained by synthesizing the image signals. Alternatively, the imaging unit 11402 may be configured to have a pair of imaging elements for respectively acquiring right-eye and left-eye image signals corresponding to 3D (dimensional) display. The 3D display enables the operator 11131 to more accurately grasp the depth of the living tissue in the surgical site. Note that when the imaging unit 11402 is configured as a multi-plate type, a plurality of systems of lens units 11401 may be provided corresponding to each imaging element.

Also, the imaging unit 11402 does not necessarily have to be provided in the camera head 11102 . For example, the imaging unit 11402 may be provided inside the lens barrel 11101 immediately after the objective lens.

The drive unit 11403 is configured by an actuator, and moves the zoom lens and focus lens of the lens unit 11401 by a predetermined distance along the optical axis under control from the camera head control unit 11405 . Thereby, the magnification and focus of the image captured by the imaging unit 11402 can be appropriately adjusted.

The communication unit 11404 is composed of a communication device for transmitting and receiving various information to and from the CCU 11201. The communication unit 11404 transmits the image signal obtained from the imaging unit 11402 as RAW data to the CCU 11201 via the transmission cable 11400 .

Also, the communication unit 11404 receives a control signal for controlling driving of the camera head 11102 from the CCU 11201 and supplies it to the camera head control unit 11405 . The control signal includes, for example, information to specify the frame rate of the captured image, information to specify the exposure value at the time of imaging, and/or information to specify the magnification and focus of the captured image. Contains information about conditions.

Note that the imaging conditions such as the frame rate, exposure value, magnification, and focus may be appropriately designated by the user, or may be automatically set by the control unit 11413 of the CCU 11201 based on the acquired image signal. good. In the latter case, the endoscope 11100 is equipped with so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function.

The camera head control unit 11405 controls driving of the camera head 11102 based on the control signal from the CCU 11201 received via the communication unit 11404.

The communication unit 11411 is composed of a communication device for transmitting and receiving various information to and from the camera head 11102 . The communication unit 11411 receives image signals transmitted from the camera head 11102 via the transmission cable 11400 .

Also, the communication unit 11411 transmits a control signal for controlling driving of the camera head 11102 to the camera head 11102 . Image signals and control signals can be transmitted by electrical communication, optical communication, or the like.

The image processing unit 11412 performs various types of image processing on the image signal, which is RAW data transmitted from the camera head 11102 .

The control unit 11413 performs various controls related to imaging of the surgical site and the like by the endoscope 11100 and display of the captured image obtained by imaging the surgical site and the like. For example, the control unit 11413 generates control signals for controlling driving of the camera head 11102 .

In addition, the control unit 11413 causes the display device 11202 to display a captured image showing the surgical site and the like based on the image signal that has undergone image processing by the image processing unit 11412 . At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition techniques. For example, the control unit 11413 detects the shape, color, and the like of the edges of objects included in the captured image, thereby detecting surgical instruments such as forceps, specific body parts, bleeding, mist during use of the energy treatment instrument 11112, and the like. can recognize. When displaying the captured image on the display device 11202, the control unit 11413 may use the recognition result to display various types of surgical assistance information superimposed on the image of the surgical site. By superimposing and presenting the surgery support information to the operator 11131, the burden on the operator 11131 can be reduced and the operator 11131 can proceed with the surgery reliably.

A transmission cable 11400 connecting the camera head 11102 and the CCU 11201 is an electrical signal cable compatible with electrical signal communication, an optical fiber compatible with optical communication, or a composite cable of these.

Here, in the illustrated example, wired communication is performed using the transmission cable 11400, but communication between the camera head 11102 and the CCU 11201 may be performed wirelessly.

An example of an endoscopic surgery system to which this technology can be applied has been described above. The present technology can be applied to the endoscope 11100, the camera head 11102 (the imaging unit 11402 thereof), and the like among the configurations described above. For example, the solid-state imaging device according to the present technology can be applied to the imaging unit 11402 . By applying the present technology to (the imaging unit 11402 of) the endoscope 11100 and the camera head 11102, the performance of the endoscope 11100 and the camera head 11102 (the imaging unit 11402 of) can be improved. Become.

Here, an endoscopic surgery system has been described as an example, but the present technology may also be applied to other systems such as a microsurgery system.

6. Example of application to mobile objects

This technology can be applied to various products. For example, the present technology may be implemented as a device mounted on any type of moving object such as automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobility, airplanes, drones, ships, and robots. .

FIG. 18 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile control system to which the technology according to the present disclosure can be applied.

A vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in FIG. 18, the vehicle control system 12000 includes a driving system control unit 12010, a body system control unit 12020, a vehicle exterior information detection unit 12030, a vehicle interior information detection unit 12040, and an integrated control unit 12050. Also, as the functional configuration of the integrated control unit 12050, a microcomputer 12051, an audio/image output unit 12052, and an in-vehicle network I/F (Interface) 12053 are illustrated.

The drive system control unit 12010 controls the operation of devices related to the drive system of the vehicle according to various programs. For example, the driving system control unit 12010 includes a driving force generator for generating driving force of the vehicle such as an internal combustion engine or a driving motor, a driving force transmission mechanism for transmitting the driving force to the wheels, and a steering angle of the vehicle. It functions as a control device such as a steering mechanism to adjust and a brake device to generate braking force of the vehicle.

The body system control unit 12020 controls the operation of various devices equipped on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a keyless entry system, a smart key system, a power window device, or a control device for various lamps such as headlamps, back lamps, brake lamps, winkers or fog lamps. In this case, body system control unit 12020 can receive radio waves transmitted from a portable device that substitutes for a key or signals from various switches. The body system control unit 12020 receives the input of these radio waves or signals and controls the door lock device, power window device, lamps, etc. of the vehicle.

The vehicle exterior information detection unit 12030 detects information outside the vehicle in which the vehicle control system 12000 is installed. For example, the vehicle exterior information detection unit 12030 is connected with an imaging section 12031 . The vehicle exterior information detection unit 12030 causes the imaging unit 12031 to capture an image of the exterior of the vehicle, and receives the captured image. The vehicle exterior information detection unit 12030 may perform object detection processing or distance detection processing such as people, vehicles, obstacles, signs, or characters on the road surface based on the received image.

The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal according to the amount of received light. The imaging unit 12031 can output the electric signal as an image, and can also output it as distance measurement information. Also, the light received by the imaging unit 12031 may be visible light or non-visible light such as infrared rays.

The in-vehicle information detection unit 12040 detects in-vehicle information. The in-vehicle information detection unit 12040 is connected to, for example, a driver state detection section 12041 that detects the state of the driver. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 detects the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041. It may be calculated, or it may be determined whether the driver is dozing off.

The microcomputer 12051 calculates control target values for the driving force generator, the steering mechanism, or the braking device based on the information inside and outside the vehicle acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040, and controls the drive system control unit. A control command can be output to 12010 . For example, the microcomputer 12051 realizes the functions of ADAS (Advanced Driver Assistance System) including collision avoidance or shock mitigation, follow-up driving based on inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, or vehicle lane deviation warning. Cooperative control can be performed for the purpose of

In addition, the microcomputer 12051 controls the driving force generator, the steering mechanism, the braking device, etc. based on the information about the vehicle surroundings acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040, so that the driver's Cooperative control can be performed for the purpose of autonomous driving, etc., in which vehicles autonomously travel without depending on operation.

Also, the microcomputer 12051 can output a control command to the body system control unit 12030 based on the information outside the vehicle acquired by the information detection unit 12030 outside the vehicle. For example, the microcomputer 12051 controls the headlamps according to the position of the preceding vehicle or the oncoming vehicle detected by the vehicle exterior information detection unit 12030, and performs cooperative control aimed at anti-glare such as switching from high beam to low beam. It can be carried out.

The audio/image output unit 12052 transmits at least one of audio and/or image output signals to an output device capable of visually or audibly notifying the passengers of the vehicle or the outside of the vehicle. In the example of FIG. 18, an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are illustrated as output devices. The display unit 12062 may include at least one of an on-board display and a head-up display, for example.

FIG. 19 is a diagram showing an example of the installation position of the imaging unit 12031. FIG.

In FIG. 19, the imaging unit 12031 has

imaging units

12101, 12102, 12103, 12104, and 12105.

The

imaging units

12101, 12102, 12103, 12104, and 12105 are provided at positions such as the front nose, side mirrors, rear bumper, back door, and windshield of the vehicle 12100, for example. An image pickup unit 12101 provided in the front nose and an image pickup unit 12105 provided above the windshield in the passenger compartment mainly acquire images in front of the vehicle 12100 .

Imaging units

12102 and 12103 provided in the side mirrors mainly acquire side images of the vehicle 12100 . An imaging unit 12104 provided in the rear bumper or back door mainly acquires an image behind the vehicle 12100 . The imaging unit 12105 provided above the windshield in the passenger compartment is mainly used for detecting preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, and the like.

Note that FIG. 19 shows an example of the imaging range of the imaging units 12101 to 12104. FIG. The imaging range 12111 indicates the imaging range of the imaging unit 12101 provided in the front nose, the imaging ranges 12112 and 12113 indicate the imaging ranges of the

imaging units

12102 and 12103 provided in the side mirrors, respectively, and the imaging range 12114 The imaging range of an imaging unit 12104 provided on the rear bumper or back door is shown. For example, by superimposing the image data captured by the imaging units 12101 to 12104, a bird's-eye view image of the vehicle 12100 viewed from above can be obtained.

At least one of the imaging units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera composed of a plurality of imaging elements, or may be an imaging element having pixels for phase difference detection.

For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 determines the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and changes in this distance over time (relative velocity with respect to the vehicle 12100). , it is possible to extract, as the preceding vehicle, the closest three-dimensional object on the traveling path of the vehicle 12100, which runs at a predetermined speed (for example, 0 km/h or more) in substantially the same direction as the vehicle 12100. can. Furthermore, the microcomputer 12051 can set the inter-vehicle distance to be secured in advance in front of the preceding vehicle, and perform automatic brake control (including following stop control) and automatic acceleration control (including following start control). In this way, cooperative control can be performed for the purpose of automatic driving in which the vehicle runs autonomously without relying on the operation of the driver.

For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 converts three-dimensional object data related to three-dimensional objects to other three-dimensional objects such as motorcycles, ordinary vehicles, large vehicles, pedestrians, and utility poles. It can be classified and extracted and used for automatic avoidance of obstacles. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into those that are visible to the driver of the vehicle 12100 and those that are difficult to see. Then, the microcomputer 12051 judges the collision risk indicating the degree of danger of collision with each obstacle, and when the collision risk is equal to or higher than the set value and there is a possibility of collision, the obstacle is detected through the audio speaker 12061 and the display unit 12062. By outputting an alarm to the driver via the drive system control unit 12010 and performing forced deceleration and avoidance steering via the drive system control unit 12010, driving assistance for collision avoidance can be performed.

At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether or not the pedestrian exists in the captured images of the imaging units 12101 to 12104 . Such recognition of a pedestrian is performed by, for example, a procedure for extracting feature points in images captured by the imaging units 12101 to 12104 as infrared cameras, and performing pattern matching processing on a series of feature points indicating the outline of an object to determine whether or not the pedestrian is a pedestrian. This is done by a procedure that determines When the microcomputer 12051 determines that a pedestrian exists in the images captured by the imaging units 12101 to 12104 and recognizes the pedestrian, the audio image output unit 12052 outputs a rectangular outline for emphasis to the recognized pedestrian. is superimposed on the display unit 12062 . Also, the audio/image output unit 12052 may control the display unit 12062 to display an icon or the like indicating a pedestrian at a desired position.

An example of a vehicle control system to which this technology can be applied has been described above. The present technology can be applied to, for example, the imaging unit 12031 among the configurations described above. Specifically, the solid-state imaging device according to the present technology can be applied to the imaging unit 12031 . By applying the present technology to the imaging unit 12031, the performance of the imaging unit 12031 can be improved.

The present technology is not limited to the above-described embodiments, usage examples, and application examples, and various modifications are possible without departing from the gist of the present technology.

In addition, the effects described in this specification are merely examples and are not limited, and other effects may also occur.

This technique can also take the following configurations.
[1]
a semiconductor substrate having a first surface that is a light incident surface and a second surface that faces the first surface;
and two or more pixels including the semiconductor substrate,
The semiconductor substrate includes, within one or more pixels, a first porous region formed on the first surface, and a non-porous region formed on the second surface side of the first porous region; having
Solid-state imaging device.
[2]
The solid-state imaging device according to [1], wherein the porosity of the first porous region increases continuously or stepwise from the second surface side toward the first surface side.
[3]
the semiconductor substrate further having a second porous region within one or more of the pixels;
The solid-state imaging device according to [1] or [2], wherein the second porous region is formed in a direction perpendicular to the first surface of the semiconductor substrate.
[4]
The solid-state imaging device according to any one of [1] to [3], wherein the semiconductor substrate further has a third porous region in one or more of the pixels.
[5]
The solid-state imaging device according to [4], wherein the third porous region is formed on the second surface of the semiconductor substrate.
[6]
The solid-state imaging device according to [4], wherein the third porous region is formed inside the non-porous region.

1 solid-state imaging device 2

pixels

11, 11A, 11B, 11C, 11D semiconductor substrates 11a, 11Aa, 11Ba, 11Ca, 11Da first surfaces 11b, 11Ab, 11Bb, 11Cb, 11Db second surfaces 12, 12A, 12B first

porous Regions

13, 13A, 13B Non-porous Region 14 Pixel Separating Portion 21 Multilayer Wiring Layer 22 Wiring Layer 23 Interlayer Insulating Film 24 Gate Electrode 31 Supporting Substrate 41 Transparent Insulating Film 51 On-Chip Lens 61 Second Porous Region 71 Third

Porous Region Regions

121, 122, 123 porous layer

Claims

a semiconductor substrate having a first surface that is a light incident surface and a second surface that faces the first surface;
and two or more pixels including the semiconductor substrate,
The semiconductor substrate includes, within one or more pixels, a first porous region formed on the first surface, and a non-porous region formed on the second surface side of the first porous region; having
Solid-state imaging device.
The solid-state imaging device according to claim 1, wherein the porosity of said first porous region increases continuously or stepwise from said second surface side toward said first surface side.
the semiconductor substrate further having a second porous region within one or more of the pixels;
2. The solid-state imaging device according to claim 1, wherein said second porous region is formed in a direction perpendicular to said first surface of said semiconductor substrate.
The solid-state imaging device according to claim 1, wherein said semiconductor substrate further has a third porous region within said one or more pixels.
The solid-state imaging device according to claim 4, wherein said third porous region is formed on said second surface of said semiconductor substrate.
The solid-state imaging device according to claim 4, wherein said third porous region is formed inside said non-porous region.