WO2018159737A1

WO2018159737A1 - Solid-state imaging device, method for producing solid-state imaging device, and electronic device

Info

Publication number: WO2018159737A1
Application number: PCT/JP2018/007702
Authority: WO
Inventors: 琢哉伊藤
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: 2017-03-03
Filing date: 2018-03-01
Publication date: 2018-09-07

Abstract

The present technique relates to: a solid-state imaging device which is capable of preventing the occurrence of flare or ghost images more reliably; a method for producing a solid-state imaging device; and an electronic device. A solid-state imaging device according to the present invention is provided with: an image sensor that has a pixel array in which a plurality of pixels are arranged in a matrix form; a light guide part which has light guide paths for guiding light respectively to the pixels and light blocking bodies that surround the light guide paths; microlenses which respectively make light incident on the light guide paths; and a light blocking part which has openings that are formed to respectively correspond to the microlenses. The light blocking part is provided with anti-reflection structures on the wall surfaces of the openings. The present technique is applicable to a solid-state imaging device for bioimaging.

Description

Solid-state imaging device, method for manufacturing solid-state imaging device, and electronic apparatus

The present technology relates to a solid-state imaging device, a method for manufacturing a solid-state imaging device, and an electronic device, and more particularly to a solid-state imaging device, a manufacturing method for a solid-state imaging device, and an electronic device that can prevent occurrence of flare and ghost. .

Conventionally, a configuration for preventing the occurrence of flare and ghost in a solid-state imaging device has been studied.

For example, Patent Document 1 provides a waveguide array having a cladding that absorbs light between an incident-side microlens array and an output-side microlens array as an image sensor applied to an image input device that reads a document. Is disclosed. With such a configuration, reflection of light in the waveguide can be suppressed and generation of ghosts and flares can be prevented.

However, in the configuration of Patent Document 1, the light intensity and the transmittance are greatly attenuated only by the deviation of the incident light to the incident side microlens array and the angle of the emitted light from the emission side microlens array. End up.

JP 2001-257835 A

In recent years, development of a solid-state imaging device for bioimaging (hereinafter referred to as a bioimaging device) for biometric authentication such as vein authentication has been actively performed, but flare and ghost also occur in the bioimaging device. There was a fear.

This technology has been made in view of such a situation, and more reliably prevents the occurrence of flares and ghosts.

A solid-state imaging device according to an embodiment of the present technology includes an image sensor having a pixel array in which a plurality of pixels are arranged in a matrix, a light guide for guiding light to each of the pixels, and a light guide unit surrounding the light guide. And a microlens for allowing the light to enter each of the light guide paths, and a light shielding portion having an opening formed corresponding to each of the microlenses, and the light shielding portion has an antireflection structure on a wall surface of the opening. Have.

A method of manufacturing a solid-state imaging device according to an embodiment of the present technology includes an image sensor having a pixel array in which a plurality of pixels are arranged in a matrix, a light guide path for guiding light to each of the pixels, and a light shielding body surrounding the light guide. In the method of manufacturing a solid-state imaging device, comprising: a light guide part; a microlens that enters the light into each of the light guide paths; and a light shielding part having an opening formed corresponding to each of the microlenses. Forming the opening corresponding to the step, and forming an antireflection structure on the wall surface of the opening.

An electronic apparatus according to an embodiment of the present technology includes an image sensor including a pixel array in which a plurality of pixels are arranged in a matrix, a light guide for guiding light to each of the pixels, and a light guide unit including a light shielding body surrounding the light guide. And a microlens for allowing the light to enter each of the light guide paths, and a light shielding portion having an opening formed corresponding to each of the microlenses, and the light shielding portion has an antireflection structure on a wall surface of the opening. A solid-state imaging device is provided.

In the present technology, an image sensor having a pixel array in which a plurality of pixels are arranged in a matrix, a light guide for guiding light to each of the pixels, and a light guide unit surrounding the light guide, In a solid-state imaging device including a microlens that enters the light into each light guide and a light-shielding unit that has an opening formed corresponding to each microlens, the opening is formed corresponding to each microlens. The antireflection structure is formed on the wall surface of the opening.

This technology makes it possible to prevent the occurrence of flares and ghosts more reliably. Note that the effects described here are not necessarily limited, and may be any of the effects described in the present disclosure.

It is the schematic which shows an example of a biological imaging system. It is a block diagram which shows the structural example of an image sensor. It is sectional drawing which shows the structural example of the conventional biological imaging device. It is sectional drawing which shows the structural example of the conventional biological imaging device. It is sectional drawing which shows the structural example of the biological imaging device to which this technique is applied. It is a top view explaining the structure of a light-shielding part. It is sectional drawing seen from the other side surface which shows the structural example of a biological imaging device. It is a figure which shows the 1st example of an antireflection structure. It is a figure which shows the 2nd example of an antireflection structure. It is a figure which shows the 3rd example of an antireflection structure. It is a figure which shows the flow of the manufacturing process of a light-shielding part. It is a figure which shows the flow of the manufacturing process of a light-shielding part. It is a figure which shows the flow of the manufacturing process of a light-shielding part. It is the schematic which shows another example of a biological imaging system. It is a block diagram which shows the structural example of the electronic device to which this technique is applied.

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. 1. Overview of biological imaging system 2. Configuration example of image sensor 3. Configuration example of biological imaging device 4. Example of antireflection structure 5. Manufacturing process of light shielding part 6. Other examples of biological imaging systems Electronic device configuration example

<1. Overview of biological imaging system>
FIG. 1 is a schematic diagram illustrating an example of a biological imaging system according to the present technology.

In the living body imaging system of FIG. 1, the light IR emitted from the light source 10 is reflected on a living body Fg such as a finger to be observed, and the living body imaging device 20 captures the reflected light, so that the state of the living body Fg is changed. Observed.

The light IR emitted from the light source 10 is, for example, near infrared light having a wavelength in the range of 660 nm to 940 nm.

The biological imaging device 20 includes an image sensor 21 and an optical system 22. The image sensor 21 captures an image by receiving reflected light of the light IR incident through the optical system 22. The image sensor 21 is configured as, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, but may be configured as a CCD (Charge Coupled Device) image sensor.

In the example of FIG. 1, the living body imaging device 20 captures reflected light in which the light IR emitted from the light source 10 is reflected by the living body Fg. However, the transmitted light in which the light IR emitted from the light source 10 passes through the living body Fg. You may make it image.

<2. Example of image sensor configuration>
FIG. 2 is a block diagram illustrating a configuration example of the image sensor 21.

The image sensor 21 in FIG. 2 includes a pixel array 31, a vertical drive circuit 32, a horizontal drive circuit 33, and an output circuit 34.

A plurality of pixels 41 are arranged in a matrix in the pixel array 31. Each pixel 41 is connected to the vertical drive circuit 32 for each row by a horizontal signal line 42, and is connected to the horizontal drive circuit 33 for each column by a vertical signal line 43.

The vertical drive circuit 32 outputs a drive signal via the horizontal signal line 42 to drive the pixels 41 arranged in the pixel array 31 for each row.

The horizontal drive circuit 33 performs column processing for detecting a signal level by a CDS (Correlated Double Sampling) operation from the pixel signal output from each pixel 41 of the pixel array 31 via the vertical signal line 43, and the pixel 41 performs photoelectric processing. An output signal corresponding to the charge generated by the conversion is output to the output circuit 34.

The output circuit 34 amplifies the output signal sequentially output from the horizontal drive circuit 33 to a voltage value of a predetermined level, and outputs it to a subsequent image processing circuit or the like.

<3. Configuration example of biological imaging device>
Next, a configuration example of the biological imaging device will be described.

(Configuration example of conventional biological imaging device)
FIG. 3 is a cross-sectional view illustrating a configuration example of a conventional biological imaging device.

FIG. 3 shows a cross-sectional view corresponding to two pixels 41 in the image sensor 21.

3, a glass seal resin 52 having a thickness of about 40 to 60 μm is formed on the image sensor 21 in the biological imaging device 50A shown in FIG. On the glass seal resin 52, a light guide 52 having a height of about 0.25 to 0.45 mm is formed.

The light guide unit 52 includes a light guide path 52a for guiding light to each of the pixels 41 and a light shielding body 52b surrounding the light guide path 52a. As a material for forming the light guide path 52a, a material having a lower refractive index than the material for forming the light shielding body 52b is used. Thereby, reflection of the light in the light guide 52a can be suppressed.

On the light guide portion 52, microlenses 53 are formed for allowing light to enter each of the light guide paths 52a. The microlens 53 is formed to have a diameter of 60 to 80 μm, a radius of curvature of 100 to 130 μm, and a sag amount of 5 to 6 μm, for example. Since the microlens 53 is provided corresponding to the pixel 41, it forms a microlens array corresponding to the pixel array 31.

A cover glass layer 55 having a thickness of about 0.5 to 0.8 mm is formed on the light guide portion 52 with an air layer 54 having a thickness of about 0.12 to 0.20 mm interposed therebetween. The cover glass layer 55 is made of SiO 2 or the like.

However, in a configuration such as the biological imaging device 50A, a ghost may occur when the light beam L1 serving as a ghost component enters an adjacent pixel.

On the other hand, the biological imaging device 50B shown in FIG.

The light shielding portion 61 has a cylindrical opening formed corresponding to each of the microlenses 53. The light shielding portion 61 is formed to have a height of, for example, 540 μm and is configured to be integrated with the cover glass layer 55. That is, the cover glass layer 55 is formed so as to fill the opening of the light shielding part 61 on the light incident side of the light shielding part 61. The thickness of the cover glass layer 55 on the light incident side of the light shielding part 61 (above the upper end of the light shielding part 61 in the drawing) is, for example, 160 μm.

However, even in the configuration of the biological imaging device 50B, flare and ghost may occur due to the light beam L1 being reflected by the wall surface of the opening of the light shielding unit 61.

Therefore, in the following, the configuration of the biological imaging device that prevents the occurrence of flare and ghost will be described more reliably.

(Configuration example of biological imaging device to which this technology is applied)
FIG. 5 is a cross-sectional view illustrating a configuration example of a biological imaging device that is a solid-state imaging device to which the present technology is applied.

The biological imaging device 20 in FIG. 5 basically includes the same configuration as the biological imaging device 50B in FIG. 4, but includes a light shielding unit 71 instead of the light shielding unit 61. In the biological imaging device 20 of FIG. 5, the light guide unit 52, the microlens 53, the cover glass layer 55, and the light shielding unit 71 correspond to the optical system 22 in the biological imaging device 20 of FIG.

The light shielding part 71 has a cylindrical opening formed corresponding to each of the microlenses 53, similarly to the light shielding part 61. Further, the light shielding portion 71 has an antireflection structure 72 on the wall surface of the opening.

FIG. 6 is a top view showing the structure of the light shielding portion 71. As shown in FIG. 6, the openings of the light shielding portions 71 are arranged in a matrix like the pixels 41. Although not shown, a microlens 53 is provided at the end of each opening in the depth direction.

Note that the cross-sectional view of the biological imaging device 20 in FIG. 5 shows a cross section taken along the broken line AB shown in FIG.

Further, the cross-sectional view of the biological imaging device 20 shown in FIG. 7 shows a cross section taken along a broken line CD shown in FIG. In FIG. 6, since the distance between the openings on the broken line CD is larger than the distance between the openings on the broken line AB, the thickness of the light shielding portion 71 in FIG. The thickness of the wall) is thicker than the thickness of the light shielding part 71 in FIG.

<4. Example of antireflection structure>
Here, a specific example of the antireflection structure 72 will be described.

(Example 1 moth eye structure)
FIG. 8 is a diagram illustrating a first example of the antireflection structure 72.

The anti-reflection structure 72A of the light shielding part 71A shown in FIG.

As shown in FIG. 8, the diameter of each protrusion constituting the moth-eye structure (in other words, the interval between the protrusions, the pitch) is in the range of 250 to 400 nm, and the height of the protrusion is in the range of 125 to 200 nm. Shall. These values can be set to appropriate values according to the wavelength of the light IR emitted from the light source 10.

(Example 2 Antireflection film)
FIG. 9 is a diagram illustrating a second example of the antireflection structure 72.

The antireflection structure 72B of the light shielding part 71B shown in FIG. 9 is an antireflection film made of, for example, MgF2.

As shown in FIG. 9, the film thickness of the antireflection film is in the range of 150 to 250 nm. This value can be set to an appropriate value according to the wavelength of the light IR emitted from the light source 10.

(Example 3 light absorption film)
FIG. 10 is a diagram illustrating a third example of the antireflection structure 72.

The antireflection structure 72C of the light shielding part 71C shown in FIG. 10 is a light absorption film made of a metal oxide. As the metal oxide, oxides such as Cu, Fe, Ni, and Ti are used. In this case, the light absorptive film has an absorptance of light having a wavelength of 1 μm of about 0.8 to 0.85.

As shown in FIG. 10, the thickness of the light absorption film is 30 nm or more, preferably about 50 nm. These values can be set to appropriate values according to the wavelength of the light IR emitted from the light source 10.

<5. Manufacturing process of light shielding part>
Next, with reference to FIG. 11 thru | or FIG. 13, the manufacturing process of the light-shielding part 71 with which the biological imaging device 20 is provided is demonstrated.

First, as shown in FIG. 11A, a SiO 2 film 112 having a thickness of, for example, 160 μm is formed on a Si substrate 111 having a thickness of, for example, 540 μm, and a resist Rg is applied thereon.

Next, as shown in FIG. 11B, the resist Rg is removed with a diameter of about 250 to 260 nm.

Thereafter, as shown in FIG. 12C, the SiO2 film 112 and the Si substrate 111 are etched by irradiation with SF6 gas clusters, so that the SiO2 film 112 and the Si substrate 111 are shown in FIG. For example, an opening having a diameter of 250 nm is formed.

Next, as shown in FIG. 13E, after the remaining resist Rg is removed, as shown in FIG. 13F, the antireflection structure 72 is formed on the wall surface of the opening of the Si substrate 111 (light shielding portion 71). Is formed.

For example, when the antireflection structure 72 has a moth-eye structure, a moth-eye structure is formed by ion etching after forming a carbon film by a plasma CVD (Chemical Vapor Deposition) method.

Further, when the antireflection structure 72 is an antireflection film, an antireflection film is formed by forming an MgF2 film by an RF sputtering method or a thermal CVD method. A vacuum deposition method or a coating method may be used for forming the MgF 2 film.

Furthermore, when the antireflection structure 72 is a light absorption film made of, for example, Cu oxide, the light absorption film is formed by an RF sputtering method in an O 2 atmosphere. In addition, after the Cu film is formed, the light absorption film can be formed by heating in the air or heating in a high vacuum infrared heating furnace.

Now, after the antireflection structure 72 is formed in this way, as shown in FIG. 13G, the openings of the SiO 2 film 112 and the Si substrate 111 (light-shielding portion 71) are filled with SiO 2 to cover the surface. A light shielding portion 71 configured to be integrated with the glass layer 55 is formed.

<6. Other examples of biological imaging systems>
In the above description, as described with reference to FIG. 1, the light source 10 and the biological imaging device 20 are configured separately. However, like the solid-state imaging device 150 illustrated in FIG. The light source 10 may be provided in the imaging device 150.

The solid-state imaging device as described above can be applied to an electronic device that performs biological imaging.

<7. Configuration example of electronic device>
FIG. 15 is a block diagram illustrating a configuration example of an electronic device to which the present technology is applied.

As illustrated in FIG. 15, the electronic device 201 includes a solid-state imaging device 211 and a DSP (Digital Signal Processor) 212, and a DSP 212, a display device 213, an operation system 214, a memory 216, and a recording device via a bus 215. 217 and a power supply system 218 are connected.

As the solid-state imaging device 211, the solid-state imaging device (biological imaging device 20) of the above-described embodiment is applied. In the solid-state imaging device 211, electrons are accumulated for a certain period according to the image formed on the light receiving surface via the optical system. Then, a signal corresponding to the electrons accumulated in the solid-state imaging device 211 is supplied to the DSP 212.

The DSP 212 performs various signal processing on the signal from the solid-state imaging device 211 to acquire an image, and temporarily stores the image data in the memory 216. The image data stored in the memory 216 is recorded in the recording device 217 or supplied to the display device 213 to display the image. The operation system 214 receives various operations by the user and supplies operation signals to each block of the electronic device 201, and the power supply system 218 supplies power necessary for driving each block of the electronic device 201.

In the electronic apparatus 201 configured as described above, by applying the biological imaging device 20 as described above as the solid-state imaging device 211, it is possible to prevent the occurrence of flare and ghost, so that a higher quality image can be obtained. Imaging can be performed.

Note that the embodiments of the present technology are not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present technology.

Furthermore, this technique can take the following structures.
(1)
An image sensor having a pixel array in which a plurality of pixels are arranged in a matrix;
A light guide having a light guide for guiding light to each of the pixels and a light shielding body surrounding the light guide, and
A microlens that enters the light into each of the light guides;
A light shielding part having an opening formed corresponding to each of the microlenses,
The light-shielding portion has an antireflection structure on a wall surface of the opening.
(2)
The solid-state imaging device according to (1), wherein the wavelength of the light is in a range of 660 to 940 nm.
(3)
The solid-state imaging device according to (2), wherein the antireflection structure is a moth-eye structure.
(4)
The solid-state imaging device according to (3), wherein an interval between protrusions constituting the moth-eye structure is in a range of 250 to 400 nm, and a height of the protrusion is in a range of 125 to 200 nm.
(5)
The solid-state imaging device according to (2), wherein the antireflection structure is an antireflection film.
(6)
The solid-state imaging device according to (5), wherein the antireflection film is made of MgF2.
(7)
The film thickness of the antireflection film is in the range of 150 to 250 nm. (5) or (6).
(8)
The solid-state imaging device according to (2), wherein the antireflection structure is a light absorption film.
(9)
The solid-state imaging device according to (8), wherein the light absorption film is made of a metal oxide.
(10)
The film thickness of the said light absorption film | membrane is 30 nm or more. The solid-state imaging device as described in (8) or (9).
(11)
The solid-state imaging device according to any one of (1) to (10), further including a glass layer formed on the light incident side of the light shielding portion so as to fill the opening of the light shielding portion.
(12)
An image sensor having a pixel array in which a plurality of pixels are arranged in a matrix;
A light guide having a light guide for guiding light to each of the pixels and a light shielding body surrounding the light guide, and
A microlens that enters the light into each of the light guides;
In a manufacturing method of a solid-state imaging device comprising: a light shielding portion having an opening formed corresponding to each of the microlenses,
Forming the opening corresponding to each of the microlenses;
A method for manufacturing a solid-state imaging device, comprising: forming an antireflection structure on a wall surface of the opening.
(13)
An image sensor having a pixel array in which a plurality of pixels are arranged in a matrix;
A light guide having a light guide for guiding light to each of the pixels and a light shielding body surrounding the light guide, and
A microlens that enters the light into each of the light guides;
A light shielding part having an opening formed corresponding to each of the microlenses,
An electronic apparatus, wherein the light shielding unit includes a solid-state imaging device having an antireflection structure on a wall surface of the opening.

10 light sources, 20 biological imaging devices, 21 image sensors, 22 optical systems, 31 pixel arrays, 41 pixels, 52 light guides, 52a light guides, 52b light shields, 53 microlenses, 55 cover glass layers, 71 light shields, 72 Antireflection structure, 150 biological imaging device, 201 electronic equipment, 211 solid-state imaging device

Claims

An image sensor having a pixel array in which a plurality of pixels are arranged in a matrix;
A light guide having a light guide for guiding light to each of the pixels and a light shielding body surrounding the light guide, and
A microlens that enters the light into each of the light guides;
A light shielding part having an opening formed corresponding to each of the microlenses,
The light-shielding portion has an antireflection structure on a wall surface of the opening.
The solid-state imaging device according to claim 1, wherein a wavelength of the light is in a range of 660 to 940 nm.
The solid-state imaging device according to claim 2, wherein the antireflection structure is a moth-eye structure.
The solid-state imaging device according to claim 3, wherein an interval between protrusions constituting the moth-eye structure is in a range of 250 to 400 nm, and a height of the protrusion is in a range of 125 to 200 nm.
The solid-state imaging device according to claim 2, wherein the antireflection structure is an antireflection film.
The solid-state imaging device according to claim 5, wherein the antireflection film is made of MgF 2.
The solid-state imaging device according to claim 5, wherein a film thickness of the antireflection film is in a range of 150 to 250 nm.
The solid-state imaging device according to claim 2, wherein the antireflection structure is a light absorption film.
The solid-state imaging device according to claim 8, wherein the light absorption film is made of a metal oxide.
The solid-state imaging device according to claim 8, wherein a film thickness of the light absorption film is 30 nm or more.
The solid-state imaging device according to claim 1, further comprising a glass layer formed on the light incident side of the light shielding portion so as to fill the opening of the light shielding portion.
An image sensor having a pixel array in which a plurality of pixels are arranged in a matrix;
A light guide having a light guide for guiding light to each of the pixels and a light shielding body surrounding the light guide, and
A microlens that enters the light into each of the light guides;
In a manufacturing method of a solid-state imaging device comprising: a light shielding portion having an opening formed corresponding to each of the microlenses,
Forming the opening corresponding to each of the microlenses;
A method for manufacturing a solid-state imaging device, comprising: forming an antireflection structure on a wall surface of the opening.
An image sensor having a pixel array in which a plurality of pixels are arranged in a matrix;
A light guide having a light guide for guiding light to each of the pixels and a light shielding body surrounding the light guide, and
A microlens that enters the light into each of the light guides;
A light shielding part having an opening formed corresponding to each of the microlenses,
An electronic apparatus, wherein the light shielding unit includes a solid-state imaging device having an antireflection structure on a wall surface of the opening.