JP2012156194A - Solid state imaging device and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid state imaging device having excellent color reproducibility and incident angle dependence.SOLUTION: The solid state imaging device includes: a light receiving unit 1 provided pixel-by-pixel for performing photoelectric conversion; dichroic prisms 11, 12, 21, 22, having dichroic mirrors 4A, 4B, 4C formed of multilayer films on one surface, disposed upward of the light receiving unit 1 with a configuration to separate, by a plurality of sets as one set, incident light into light of a plurality of wavelength bands, so as to allow the light of each wavelength band to be incident to the light receiving unit 1 of different pixels, and disposed to have the direction of a reflection plane of the dichroic mirrors 4A, 4B, 4C to be symmetric relative to a center line C of an imaging region; and color filters 2B, 2G, 2R disposed downward of the dichroic prisms 11, 12, 21, 22 and on the light receiving unit.

Description

  The present invention relates to a solid-state imaging device and an imaging device including the solid-state imaging device.

  In order to obtain a color image in a solid-state imaging device, usually, incident light is separated into light of three colors of red (R), green (G), and blue (B) and guided to a light receiving unit. Photoelectric conversion is performed.

In order to separate the light into these three colors, a method mainly used is an absorption color filter.
This absorption color filter has a characteristic of transmitting only wavelengths in a specific band and absorbing wavelengths in other bands.

  However, since the absorption color filter has a characteristic of absorbing light outside the transmitted wavelength band, for example, light incident on a red light receiving part absorbs green and blue, and the light use efficiency is 1 /. Will be reduced to 3.

Therefore, in order to avoid a decrease in light utilization efficiency, a spectroscopic method using a dichroic prism has been proposed (see, for example, Patent Document 1 and Patent Document 2).
According to this method, a specific wavelength is transmitted (reflected) by the dichroic prism, and incident light can be separated into three colors of R / G / B.
If this method is used in the color filter section of a single-plate solid-state image sensor, incident light can be separated into three colors of R / G / B without loss due to absorption, and further improvement in light utilization efficiency can be achieved. Can be planned.

In the configuration described in FIG. 2 of Patent Document 1, a dichroic prism is stacked in two layers to realize a solid-state imaging device that can split three colors of R / G / B in a Bayer arrangement.
The dichroic prism is formed by depositing an oxide film or the like into a prism shape and then depositing a multilayer film on the surface.

In the configuration described in FIG. 1 of Patent Document 2, incident light is collected by a microlens, and is controlled so as to be incident only on the first dichroic prism by a light shielding layer.
Then, in the first dichroic prism, the blue light is transmitted and incident on the first light receiving surface below, the green light and the red light are reflected, and are guided to the second dichroic prism on the side. Yes.
In the second dichroic prism, the green light is reflected and incident on the second light receiving surface below, and the red light is transmitted and guided to the side third dichroic prism.
In the third dichroic prism, red light is reflected and incident on the third light receiving surface below.
The first to third dichroic prisms are formed on the same plane.

  Although the two configurations described above are different from a single-layer prism and a two-layer prism, the basic spectroscopic method for separating light to be transmitted and reflected and guiding light to a desired pixel portion is the same. It has become.

JP 2007-259232 A JP 2004-200388 A

  However, since the dichroic mirror used in the dichroic prism is formed of a multilayer film, the spectral characteristic has an incident angle dependency, and the spectral characteristic is biased depending on the position of the pixel in the imaging region.

That is, for example, as shown in FIG. 21, when the orientations of the dichroic prisms 51 are all set to be the same in the imaging region, the incident angle with respect to the multilayer dichroic mirror differs between the left side and the right side of the center of the field angle, Becomes asymmetrical on the left and right.
Furthermore, when an image is picked up by a solid-state imaging device having a dichroic prism in a spectral structure, color unevenness occurs in the acquired image due to the angle dependence inherent in the dichroic mirror.
It is necessary to minimize the influence that the spectrum changes due to the incident angle.

In the configuration described in FIG. 2 of Patent Document 1, a collimator is disposed under the microlens so that incident light to the prism is parallel light. However, the incident light on the sensor surface is premised on parallel light incident perpendicularly to the main surface of the solid-state imaging device, and light incident obliquely is not considered.
In the configuration described in FIG. 1 of Patent Document 2, incident light is regulated by a mask layer provided between the microlens and the prism. Only light incident perpendicularly to the main surface is considered, and light incident obliquely is not considered.
In any of the configurations described in Patent Document 1 and Patent Document 2, light obliquely incident on the main surface of the solid-state imaging device is not considered. Therefore, it is vulnerable to angle dependency, and color unevenness or the like occurs due to changes in spectral characteristics within the field angle.

By the way, the multilayer dichroic mirror used in the dichroic prism can generally reduce the ripple in the transmission wavelength band and the reflection wavelength band as the film is formed. Therefore, in general, the larger the number of layers, the better the spectral characteristics. Become a mirror.
However, as the multilayer film is formed, the actual spectral characteristics vary with respect to the desired spectral characteristics due to manufacturing tolerances.
For example, when a dichroic mirror is formed by forming a multilayer film of 20 layers, the layer thickness of the entire multilayer film becomes as thick as about 2 μm. Therefore, in the current minute pixel, such a layer is formed on the dichroic prism. It is difficult to form a large number of multilayer films.
Therefore, it is necessary to perform spectroscopy using a dichroic mirror having a small layer thickness and a small number of layers in accordance with the miniaturization of pixels.

However, generally, when the number of layers of the multilayer film is small, the slope at the rise and fall of the spectral characteristics becomes loose (see FIG. 20A).
If the slope of the spectral characteristic is loose in this way, the bottom part of the slope becomes a color mixture component with other colors, and the color purity deteriorates.
For this reason, a spectral structure is desired in which the color purity is not deteriorated even when the number of layers of the dichroic mirror is small.

  In order to solve the above-described problems, the present invention provides a solid-state imaging device and an imaging device including the solid-state imaging device that are excellent in color reproducibility and incident angle dependency.

The solid-state imaging device of the present invention includes a light receiving unit that is provided in each pixel and performs photoelectric conversion.
In addition, a dichroic mirror is formed by a multilayer film on one surface, and includes a dichroic prism provided above the light receiving unit.
Furthermore, a color filter is provided below the dichroic prism and on the light receiving unit.
The dichroic prism has a configuration in which a plurality of the dichroic prisms are separated into light of a plurality of wavelength bands by a plurality of combinations, and light of each wavelength band is incident on a light receiving unit of a different pixel. . Further, the reflecting surfaces of the dichroic mirrors are arranged so as to be symmetric with respect to the center line of the imaging region.

  The imaging device of the present invention includes a condensing optical unit that collects incident light, a solid-state imaging device, and a signal processing unit that processes a signal obtained by photoelectric conversion by the solid-state imaging device, and the solid-state imaging device The configuration of the solid-state imaging device of the present invention described above.

According to the configuration of the above-described solid-state imaging device of the present invention, the dichroic prism separates incident light into light of a plurality of wavelength bands by combining a plurality of light beams into a plurality of wavelength bands, and light in each wavelength band. Is incident on the light receiving portions of different pixels. As a result, it is possible to reduce the loss of light at the time of spectroscopy and increase the light utilization efficiency as compared with the spectral method using only a color filter.
Since the direction of the reflection surface of the dichroic mirror is arranged so as to be symmetric with respect to the center line of the imaging region, the incident angle of the incident light to the reflection surface is symmetric with respect to the center line in the pixels on both sides of the center line. can do. This makes it possible to suppress the difference in spectral characteristics between pixels on both sides of the center line with respect to obliquely incident light, and to suppress the occurrence of color unevenness due to the difference in spectral characteristics.
In addition, since a color filter is arranged below the dichroic prism and on the light receiving section, the color filter can be used to display dispersion characteristics due to tolerances in the production of multilayer films of dichroic mirrors and spectral characteristics that have changed due to changes in incident angles. Can be corrected. Thereby, it is possible to improve the color purity by aligning the spectral characteristics of the pixels. Further, even if the number of layers of the multilayer film is reduced, the transmission band that is widened by the reduction can be corrected by the color filter, so that sufficient color purity can be realized.

  According to the configuration of the imaging apparatus of the present invention described above, since the solid-state imaging device is the configuration of the solid-state imaging device of the present invention, the occurrence of color unevenness due to the difference in spectral characteristics is suppressed in the captured image, and the color purity Can be improved.

According to the above-described present invention, it is possible to suppress the occurrence of color unevenness due to a difference in spectral characteristics, and to improve color purity by correcting spectral characteristics deformed due to an incident angle and manufacturing tolerances in a color filter. Is possible.
As a result, a solid-state imaging device excellent in color reproducibility and incident angle dependency can be realized, and an image having sufficient color purity and good image quality can be obtained.

In addition, since the present invention employs a spectroscopic method that uses both a dichroic prism and a color filter, it is possible to increase the light use efficiency as compared with a spectroscopic method using only a color filter.
Further, by giving the color filter the role of controlling the spectral characteristics, the color purity can be increased without increasing the number of layers of the multilayer film.

1 is a schematic configuration diagram (cross-sectional structure diagram for three pixels) of a solid-state imaging device according to a first embodiment of the present invention. FIG. 2 is a plan view of a pixel arrangement in an imaging region of the solid-state imaging device of FIG. 1 and an arrangement diagram of a dichroic prism. It is a top view of the dichroic prism of FIG. It is a top view of one form of arrangement | positioning of the micro lens of the solid-state image sensor of FIG. It is a top view of other forms of arrangement | positioning of the micro lens of the solid-state image sensor of FIG. It is a figure which shows the arrangement | sequence of one form of 2x2 square pixel arrangement | sequence. FIGS. 4A and 4B are schematic configuration diagrams (cross-sectional structure diagram of three pixels) of a solid-state imaging device according to a second embodiment of the present invention. FIGS. FIG. 8 is a plan view of a pixel arrangement in an imaging region of the solid-state imaging device of FIG. 7 and an arrangement diagram of a dichroic prism. It is a top view of one form of arrangement | positioning of the micro lens of the solid-state image sensor of FIG. It is a top view of other forms of arrangement | positioning of the micro lens of the solid-state image sensor of FIG. It is a schematic block diagram (cross-section figure for 6 pixels) of the solid-state image sensor of the 3rd Embodiment of this invention. FIG. 12 is a plan view of a pixel arrangement in an imaging region of the solid-state imaging device of FIG. 11 and an arrangement diagram of a dichroic prism. It is a top view of one form of arrangement | positioning of the micro lens of the solid-state image sensor of FIG. It is a top view of other forms of arrangement | positioning of the micro lens of the solid-state image sensor of FIG. It is a schematic block diagram (block diagram) of the imaging device of the 4th Embodiment of this invention. It is a figure which shows the case where the direction of a dichroic prism is made symmetrical with respect to the center of an angle of view. A, B It is a figure which shows the change of the spectral characteristics when an incident angle changes 10 degree | times with the structure of FIG. It is sectional drawing which extracted the spectral structure part of one form of the solid-state image sensor of this invention. A to C are diagrams illustrating correction of spectral characteristics by the color filter according to the present invention. It is a figure which shows the change of the spectral characteristics by the combination of a dichroic prism and a color filter in A and B red pixels. It is a figure which shows the case where all the directions of a dichroic prism are made the same within an imaging region. A and B are diagrams showing changes in spectral characteristics when the incident angle changes by 10 degrees in the configuration of FIG.

Hereinafter, the best mode for carrying out the invention (hereinafter referred to as an embodiment) will be described.
The description will be given in the following order.
1. 1. Outline of the present invention First embodiment (solid-state imaging device)
3. Second embodiment (solid-state imaging device)
4). Third embodiment (solid-state imaging device)
5. Fourth embodiment (imaging apparatus)

<1. Summary of the present invention>
First, an outline of the present invention will be described prior to description of specific embodiments of the present invention.

If the orientations of the dichroic prisms are all the same in the imaging region as in the configurations described in Patent Literature 1 and Patent Literature 2, the spectral characteristics are asymmetric in the plane.
This will be described with reference to FIG.
The incident angle to the dichroic prism is 45 degrees with respect to the dichroic mirror when vertically incident on the solid-state imaging device.
On the other hand, as shown in FIG. 21, when the light enters the solid-state imaging device obliquely so as to spread from the center of the angle of view to the left and right, the left dichroic prism 51 changes the incident angle in the minus direction, and the right dichroic prism. At 52, the incident angle changes in the plus direction.
The spectral characteristics at this time are shown in FIGS. 22A and 22B. 22A and 22B, dotted lines indicate spectral characteristics when the incident angle is 45 degrees, and solid lines indicate spectral characteristics when the incident angles change by -10 degrees and +10 degrees, respectively.
When the incident angle fluctuates in the minus direction, the transmission band width tends to become wide as shown in FIG. 22A.
When the incident angle fluctuates in the plus direction, the transmission band width tends to narrow as shown in FIG. 22B.
Therefore, when the dichroic prism is arranged so that the incident angle is swung toward the minus side, as shown in FIG. 22A, the transmission band width is widened, and a decrease in sensitivity can be prevented.

Therefore, in the present invention, the dichroic prism is disposed so that the direction of the dichroic prism is symmetric with respect to the center of the field angle of the incident light.
That is, the dichroic prisms on the light receiving portions of the respective pixels are arranged so that the direction of the reflecting surface of the dichroic mirror is symmetric with respect to the center line of the imaging region corresponding to the center of the field angle of incident light.
As a result, the direction in which the incident angle of the obliquely incident light changes with respect to the incident angle of the vertically incident light can be aligned in the dichroic prisms on both sides of the center line of the imaging region. The difference in spectral characteristics depending on the position can be kept small.
In the present invention, the above-described “imaging region” does not include a pixel region where light is not incident, such as a so-called optical black pixel.

  In the present invention, the dichroic prism has a plurality of wavelength bands (for example, for example, incident light) by combining a plurality of dichroic prisms in the same manner as conventionally proposed configurations such as Patent Document 1 and Patent Document 2. The three wavelength bands (red, green, and blue) are separated. Then, the separated light of each wavelength band is made incident on the light receiving portions of different pixels (for example, a red pixel, a green pixel, and a blue pixel).

In the present invention, it is more preferable that at least the reflecting surface of the dichroic prism on which incident light first enters among the plurality of sets of dichroic prisms is arranged to face the center line side of the imaging region. With this arrangement, the angle of incidence on the reflecting surface of the dichroic prism is smaller for light that is obliquely incident on the solid-state image sensor than for light that is vertically incident on the solid-state image sensor (around 45 degrees). Thereby, it is possible to widen the transmission band width of the spectral characteristics at the light receiving portion of the green (G) pixel, and it is possible to prevent a decrease in sensitivity due to oblique incidence on the solid-state imaging device.
That is, for example, as shown in FIG. 16, the left dichroic prism 41 is disposed so that the incident surface of the left dichroic prism 41 faces the upper right and the incident surface of the right dichroic prism 42 faces the upper left with respect to the center of the angle of view.
As a result, in both the left and right dichroic prisms 41 and 42, the incident angle fluctuates in the minus direction with respect to the oblique incident light, so that the transmission band width can be widened.
The spectral characteristics at this time are shown in FIGS. 17A and 17B. In FIG. 17A and FIG. 17B, the dotted line indicates the spectral characteristics when the incident angle is 45 degrees, and the solid line indicates the spectral characteristics when the incident angles change by −10 degrees and +10 degrees, respectively.
As shown in FIGS. 17A and 17B, the transmission band width can be widened on both the left side, the right side, and the right side, so that a decrease in sensitivity can be prevented.

Note that the number of a set of dichroic prisms and the direction of the reflecting surface of a dichroic prism other than the dichroic prism to which incident light first enters are appropriately selected according to the pixel arrangement (pixel color arrangement).
For example, for a pixel arrangement in which three colors of R, G, and B are arranged in a stripe shape, the number of one set is four and two are arranged in two upper and lower layers, or the number of one set is three. A configuration in which three are arranged in a layer is conceivable. In addition, in the configuration in which the number of one set is four and two are arranged in two upper and lower layers, two upper layers including the first incident light is incident, and the reflection surface is on the center line side of the imaging region. Arrange to face. Further, in a configuration in which the number of one set is three and three are arranged in one layer, all three are arranged so that the reflecting surface faces the center line side of the imaging region.
Also, for example, for a pixel array in which an array pattern of 4 pixels of 2 vertical pixels × 2 horizontal pixels is repeatedly arranged, one set of 4 elements is arranged in two layers in the upper and lower layers, and two reflections in the lower layer are arranged. A configuration may be considered in which the orientation of the surface is 90 degrees different from the orientation of the two upper reflective surfaces.

The multilayer dichroic mirror used for the dichroic prism can be formed using a dielectric material such as TiO ₂ , Ta ₂ O ₅ , or SiO ₂ .
The multilayer dichroic mirror can be formed by vapor deposition, IAD (Ion beam Assisted Deposition), sputtering, CVD, or the like.

Furthermore, in the present invention, in order to correct the spectral characteristics of the dichroic mirror, a color filter is provided below the dichroic prism and above the light receiving unit.
The spectral characteristics of a dichroic mirror using a multilayer film vary depending on the angle of incidence on the mirror and tolerances in manufacturing the multilayer film.
In the present invention, since the color filter is arranged below the dichroic prism and above the light receiving unit, the spectral characteristics changed as described above in the dichroic mirror are corrected by the color filter.
Since the spectral characteristics are corrected by the color filter, the color purity can be increased.
In order to increase the color purity, it is conceivable to increase the number of layers of the multilayer film of the dichroic mirror. However, by using a color filter in combination, the color purity can be increased without increasing the number of layers of the multilayer film.

Here, a spectral structure part of one embodiment of the solid-state imaging device of the present invention is extracted and a cross-sectional view is shown in FIG.
In FIG. 18, the light receiving unit 1 (B) for the left blue pixel, the light receiving unit 1 (G) for the central green pixel, and the light receiving unit 1 (R) for the right red pixel are taken as one set. These are shown side by side, and color filters and dichroic prisms corresponding to these three pixels are shown.
The dichroic prism 11 disposed in the center green pixel and the dichroic prism 12 disposed in the right red pixel constitute a first layer dichroic prism 10. These upper dichroic prisms 10 (11, 12), which are the upper layers, are arranged so that the incident surfaces face the upper right.
A dichroic prism 21 arranged in the center green pixel and a dichroic prism 22 arranged in the left blue pixel constitute a second dichroic prism 20 in the lower layer. These lower second dichroic prisms 20 (21, 22) are arranged so that the incident surface faces the upper left. Dichroic mirrors 4A, 4B, 4C, and 4D made of a multilayer film are provided on the upper surfaces of the dichroic prisms 11, 12, 21, and 22.
On the light receiving portion 1, color filters 2B, 2G, 2R and an inter-pixel light shielding portion 3 made of a light shielding material are arranged. The inter-pixel light-shielding unit 3 is provided between two adjacent pixels. By providing the inter-pixel light-shielding unit 3, an optical color mixing component can be reduced.

By the first dichroic prism 10 (11, 12) of the upper layer, the green G and blue B light is transmitted, the red R light is reflected and guided to the light receiving unit 1 (R) of the red R pixel. That is, the dichroic mirror 4A of the dichroic prism 11 has characteristics of transmitting green G and blue B light and reflecting red R light, and the dichroic mirror 4B of the dichroic prism 12 transmits red R light. It has the property of reflecting.
The transmitted green G and blue B light is transmitted by the lower dichroic prism 20 (21, 22) of the lower layer, the green G light is transmitted, the blue B light is reflected, and the light receiving unit 1 ( G), 1 (B). That is, the dichroic mirror 4C of the dichroic prism 21 has a characteristic of transmitting green G light and reflecting blue B light, and the dichroic mirror 4D of the dichroic prism 22 reflects blue B light. Have

FIG. 18 shows the spectral structure portion of the left pixel at the center of the angle of view shown in FIGS. 16 and 17A.
In the pixel on the right side of the center of the angle of view, the arrangement is opposite to that in FIG. That is, the blue B pixel is arranged to the right of the green G pixel, and the red R pixel is arranged to the left of the green G pixel. Then, the incident surface of the upper first dichroic prism 10 (11, 12) is directed to the upper left, and the incident surface of the lower second dichroic prism 20 (21, 22) is directed to the upper right.

Usually, the color filter is used alone for the spectroscopy of each pixel of the solid-state imaging device.
On the other hand, in the present invention, the color filter itself is not subjected to spectroscopy alone, but the color filter is coupled with a dichroic prism to perform spectroscopy.

By the way, when performing spectroscopy using an absorption color filter as in a normal solid-state imaging device, colors other than the desired color are lost due to absorption. For example, in the case of a red color filter, it has spectral characteristics such that the blue and green wavelength bands are absorbed and only the red wavelength band is transmitted. Therefore, only 1/3 of the three primary colors that are incident should be used. I can't.
On the other hand, in the spectroscopy using a dichroic prism, incident light is divided into three colors, so that theoretically no loss occurs.

In the present invention, the color filter is provided to improve the color purity by correcting the light dispersed by the dichroic prism with the spectral characteristics of the color filter. This will be described with reference to FIGS. 19A to 19C.
First, as described above, when the incident light has an angular distribution, the dichroic prism is arranged symmetrically at the center of the angle of view, so that the incident angle dependence of the spectral characteristics is symmetric, and the green G light The incident surface of the dichroic prism is directed so that the transmission band is widened. Thereby, as shown to FIG. 19A, the transmission band of the light of green G spreads.
The color filter has a spectral characteristic that can be corrected to be the same as the spectral characteristic when the incident light angle is 0 degrees (corresponding to the center of the angle of view). For example, as shown in FIG. 19B, a spectral characteristic is provided in which the transmittance of the transmission band is high when the incident light angle is 0 degrees, and the transmittance of the bands before and after that is low.
Then, by multiplying the spectrum by the dichroic prism and the absorption color filter, as shown in FIG. 19C, the corrected spectral characteristic (solid line) is compared with the spectral characteristic (thin line) when the incident light angle is 0 degree. Thus, the same spectral characteristics can be obtained. That is, it becomes possible to correct the spectral characteristic changed due to the incident angle dependency so as to have the same spectral characteristic as the center of the angle of view.

In the present invention, the spectral characteristics of the color filters are not those that cause the spectrum to be split separately, and it is only necessary to have optimal spectral characteristics for correction. For this reason, the material and spectral characteristics of the color filter may not be the same as the material and spectral characteristics of the color filter used in a normal solid-state imaging device. Further, a thin film may be used as compared with a color filter used in a normal solid-state image sensor.
If the absorption color filter alone is used, the amount of light will be reduced to 1/3. However, in the present invention, since the monochromatic light after the dichroic prism is spectrally corrected by the color filter, only the amount changed by the incident angle is obtained. Absorption loss is small because it is absorbed.

Furthermore, the use of a color filter can be expected to reduce the number of layers of the multilayer dichroic mirror in addition to correcting the incident angle dependence of the spectral characteristics.
This will be described with reference to FIG. 20, taking a red R pixel as an example.

FIG. 20A shows four configurations of an ideal dichroic mirror having a large number of layers and sufficient spectral characteristics, a dichroic mirror having a small number of layers, and a red color filter (thickness t = 150 nm, 300 nm). Are shown side by side.
As shown in FIG. 20A, a dichroic mirror with a small number of layers generally has a gentle spectrum compared to an ideal dichroic mirror.
Here, when a red color filter (thickness t = 150 nm, 300 nm) is combined with a small number of dichroic mirrors, the spectral characteristics shown in FIG. 20B are obtained. As can be seen from FIG. 20B, even a dichroic mirror with a small number of layers can be brought close to the spectral characteristics of an ideal dichroic mirror by combining color filters.
Note that the loss of light quantity absorbed by the color filter increases as the color filter becomes thicker.
Considering the improvement of the spectral characteristics and the light loss in the case of using a color filter alone, the benefits of the improvement of the spectral characteristics and the improvement of the light utilization efficiency are greater than the loss of light quantity absorbed by this color filter. That is, in total, a high effect can be obtained by combining color filters.

By using the spectrum of the dichroic mirror multilayer film and the color filter in combination, the color purity can be improved. Unlike the configuration in which the color filter is used alone, the incident light is absorbed after the colors are separated by the dichroic mirror, so that the loss of light amount is small, and the excess color mixture component is absorbed, so that the color purity can be improved.
By giving the color filter the role of spectroscopy, the spectral characteristics can be corrected while reducing the number of layers of the multilayer dichroic mirror. And the manufacturing process can be simplified by reducing the number of layers of the multilayer dichroic mirror.

In the present invention, as described above, an absorption type color filter made of a material different from the absorption type color filter used in a normal solid-state imaging device can be used as the color filter.
It is also possible to use a color filter that diverges according to a principle other than absorption. For example, a color filter having a configuration in which a specific wavelength band is transmitted and another wavelength band is reflected or attenuated by interference using the principle of a multilayer film also used in a dichroic mirror can be considered.

<2. First Embodiment (Solid-State Imaging Device)>
1 to 5 show schematic configuration diagrams of a solid-state imaging device according to a first embodiment of the present invention.
In this embodiment, the pixel arrangement is a stripe pixel arrangement in which three colors of R / G / B are arranged in the x direction.
FIG. 1 shows a cross-sectional structure diagram for three pixels, FIG. 2 shows a plan view of the pixel arrangement in the imaging region, a corresponding dichroic prism arrangement, and FIG. 3 shows a plan view of the dichroic prism. 4 shows a plan view of one form of the arrangement of microlenses, and FIG. 5 shows a plan view of another form of the arrangement of microlenses.

As shown in FIG. 1, the solid-state imaging device according to the present embodiment is composed of a photodiode formed in a semiconductor layer, and includes a light receiving unit 1 that performs photoelectric conversion, and a color filter 2 </ b> B provided on the light receiving unit 1. 2G, 2R. A blue color filter 2B is disposed on the light receiving portion 1 (B) for the blue pixel, a green color filter 2G is disposed on the light receiving portion 1 (G) for the green pixel, and a light receiving portion for the red pixel. A red color filter 2R is arranged on 1 (R).
An inter-pixel light shielding portion 3 made of a light shielding material is formed on the light receiving portion 1 near the boundary between adjacent pixels. As the light shielding material of the inter-pixel light shielding unit 3, a metal or alloy film or the like can be used.
On the color filters 2B, 2G, and 2R, a lower second dichroic prism 20 (21, 22) and an upper first dichroic prism 10 (11, 12) are provided. In each of the dichroic prisms 11, 12, 21, and 22, dichroic mirrors 4A, 4B, 4C, and 4D formed of multilayer films are formed on one surface (upper surface) on which light is incident. That is, the configuration is such that incident light is separated into three wavelength bands of red, green, and blue by a combination of a set of four dichroic prisms 11, 12, 21, and 22.
The arrangement relationship among the light receiving unit 1, the color filters 2B, 2G, and 2R and the dichroic prisms 11, 12, 21, and 22 is the same as that shown in FIG.
Further, a collimating lens 5 that converts incident light into parallel light is provided directly above the dichroic prism 11. Further, a microlens 6 that focuses incident light is provided above the collimating lens 5.

The dichroic prisms 11, 12, 13, and 14 can be formed using a conventionally known method.
For example, as described in FIG. 12 of Patent Document 1, after a resin layer is patterned to form a prism shape, the prism shape is transferred to a prism material film under the resin film by etch back. Can be used.
Further, for example, the prism material film may be directly processed into a prism shape by a semiconductor process such as etching.
As the material film of the prism, for example, a transparent oxide film such as a SiO ₂ film can be used.

The dichroic mirrors 4A, 4B, 4C, and 4D using the multilayer film can be formed using, for example, a dielectric material such as TiO ₂ , Ta ₂ O ₅ , or SiO ₂ .
The dichroic mirrors 4A, 4B, 4C, and 4D using multilayer films can be formed by vapor deposition, IAD (Ion beam Assisted Deposition), sputtering, CVD, or the like.

In the solid-state imaging device of the present embodiment, incident light is collimated by collimating lens 5 by condensing light for three pixels of R / G / B on the upper side of green G pixel by micro lens 6. Refract to light.
The first layer dichroic prism 10 (11, 12) transmits green G and blue B light, reflects red R light, and guides it to the light receiving unit 1 (R) of the red R pixel. That is, the dichroic mirror 4A of the dichroic prism 11 has characteristics of transmitting green G and blue B light and reflecting red R light, and the dichroic mirror 4B of the dichroic prism 12 transmits red R light. It has the property of reflecting.
Further, the transmitted green G and blue B light is transmitted through the second layer dichroic prism 20 (21, 22), while green B is reflected, and blue B is reflected. And 1 (B). That is, the dichroic mirror 4C of the dichroic prism 21 has a characteristic of transmitting green G light and reflecting blue B light, and the dichroic mirror 4D of the dichroic prism 22 reflects blue B light. Have

  The dichroic mirror 4A and the dichroic mirror 4B may have the same configuration. Further, the dichroic mirror 4C and the dichroic mirror 4D may have the same configuration. In this way, by using the same configuration of the dichroic mirror, there is no need to create a dichroic mirror for each pixel, and the same layer dichroic mirror of the first layer or the second layer is manufactured by a single multilayer film forming process. can do.

In the present embodiment, the spectral structure for three pixels shown in FIG. 1 is regarded as one unit, and a large number of units are arranged in the imaging region of the solid-state imaging device.
Then, as shown in the plan view of FIG. 2, pixels of the same color are arranged in stripes in the y direction (so-called vertical direction).
On the other hand, in the x direction (so-called horizontal direction), pixels of three colors R, G, and B are arranged symmetrically with respect to the center line C of the imaging region corresponding to the above-described center of the angle of view. The dichroic prisms 11, 12, 22, and 21 are arranged symmetrically in the center of the imaging region in the x direction, as schematically shown in the upper diagram of FIG.
In FIG. 2, the positions of the three colors R, G, and B in the plan view in the lower diagram and the positions of the dichroic prisms 11, 12, 21, and 22 in the upper diagram do not correspond vertically. In practice, as shown in FIG. 1, the dichroic prism 11 and the dichroic prism 21 are arranged in the green G pixel, the dichroic prism 12 is arranged in the red R pixel, and the dichroic prism 22 is arranged in the blue B pixel. Is done.

The arrangement of a set of four dichroic prisms 11, 12, 22, and 21 is the same as that in FIG. 1 for the pixels on the left side of the center line C in the imaging region. The direction is opposite to 1.
The upper dichroic prisms 11 and 12 including the dichroic prism 11 on which the incident light first enters are arranged so that the reflecting surfaces of the dichroic mirrors 4A and 4B are directed toward the center line C. . On the other hand, the lower dichroic prisms 21 and 22 of the second layer are arranged so that the reflecting surfaces of the dichroic mirrors 4C and 4D face the side opposite to the center line C.
In the present embodiment, since pixels of the same color are arranged in a stripe shape in the y direction, the dichroic prisms 11, 12, 21, and 22 do not need to be separated for each pixel in the y direction.
Therefore, as shown in the plan view of FIG. 3, the dichroic prisms 11, 12, 21, and 22 can be formed continuously in the y direction. By making the shape continuous in the y direction, the manufacturing process of the dichroic prisms 11, 12, 21, 22 is simplified and manufactured more easily than in the case where the y direction of the dichroic prism is also separated for each pixel. be able to.

  Of the four dichroic prisms 11, 12, 21, and 22 in the set, the two dichroic prisms 12 and 22 that only reflect light and do not transmit light are used instead of the dichroic mirrors 4B and 4D. A simple reflection mirror may be used. For example, a reflection mirror made of a metal film (Al film or the like) or an alloy film can be used.

Next, one form of arrangement | positioning of the micro lens 6 of the solid-state image sensor of this Embodiment is shown in FIG. In the arrangement shown in FIG. 4, one horizontally long microlens 6 is arranged on three horizontal pixels with respect to a square pixel. The microlens 6 is arranged on the three pixels arranged in a blue B pixel, a green G pixel, and a red R pixel from the left.
4 shows the arrangement of the microlenses 6 of the pixels on the left side of the center line C in the imaging region of FIG. In the pixel on the right side of the center line C in the imaging region of FIG. 2, the microlens is placed on the three pixels lined up with the red R pixel, the green G pixel, and the blue B pixel from the left, contrary to FIG. 6 is arranged.

FIG. 5 shows another form of arrangement of the microlenses 6 of the solid-state imaging device of the present embodiment. In the arrangement shown in FIG. 5, the substantially square microlenses 6 are arranged on three horizontal pixels with respect to a vertically long rectangular pixel that is three times as long as the horizontal. The microlens 6 is arranged on the three pixels arranged in a blue B pixel, a green G pixel, and a red R pixel from the left.
FIG. 5 shows the arrangement of the microlenses 6 of the pixels on the left side of the center line C in the imaging region of FIG. In the pixel on the right side of the center line C in the imaging region of FIG. 2, the microlens is placed on the three pixels lined up with the red R pixel, the green G pixel, and the blue B pixel from the left, contrary to FIG. 6 is arranged.

  According to the configuration of the solid-state imaging device of the present embodiment described above, the orientation of the reflecting surfaces of the dichroic mirrors 4A, 4B, 4C, and 4D of the dichroic prisms 11, 12, 21, and 22 is symmetrical with respect to the center line C of the imaging region. It is arranged to be. For this reason, in the pixels on both sides of the center line C, the incident angle of the incident light on the reflecting surface can be made symmetric with respect to the center line C. Accordingly, it is possible to suppress the difference in spectral characteristics between the pixels on both sides of the center line C with respect to the obliquely incident light, and it is possible to suppress the occurrence of color unevenness due to the difference in spectral characteristics.

  Further, color filters 2R, 2G, and 2B are disposed on the light receiving unit 1 below the dichroic prisms 11, 12, 21, and 22. For this reason, the color filters 2R, 2G, and 2B can correct the dispersion due to tolerances at the time of manufacturing the multilayer film of the dichroic mirrors 4A, 4B, 4C, and 4D and the spectral characteristics changed due to the change in the incident angle. Thereby, it is possible to improve the color purity by aligning the spectral characteristics of the pixels. Further, even if the number of layers of the multilayer film is reduced, the transmission band widened by the reduction can be corrected by the color filters 2R, 2G, and 2B, so that sufficient color purity can be realized.

According to the present embodiment, as described above, it is possible to suppress the occurrence of color unevenness due to the difference in spectral characteristics, and the color characteristics deformed by the incident angle and manufacturing tolerances are corrected by the color filter. Purity can be improved.
As a result, a solid-state imaging device excellent in color reproducibility and incident angle dependency can be realized, and an image having sufficient color purity and good image quality can be obtained.

Further, since the spectral method using both the dichroic prisms 11, 12, 21, and 22 and the color filters 2R, 2G, and 2B is adopted, it is possible to increase the light utilization efficiency compared to the spectral method using only the color filter. is there.
Further, by giving the color filter the role of controlling the spectral characteristics, the color purity can be increased without increasing the number of layers of the dichroic mirrors 4A, 4B, 4C, and 4D.

Furthermore, according to the present embodiment, the upper dichroic prisms 11 and 12 including the dichroic prism 11 on which the incident light is first incident, the reflecting surfaces of the dichroic mirrors 4A and 4B are center lines of the imaging region. It arrange | positions so that it may face the C side.
Thereby, when light is incident on the solid-state imaging device obliquely, the change in the spectral characteristics of the dichroic mirror 4A of the dichroic prism 11 is widened in both the pixels on the center line C so that the transmission band width is widened. Can do.
Accordingly, it is possible to prevent a decrease in sensitivity due to oblique incidence on the solid-state imaging device, and to improve color purity and sensitivity.

<3. Second Embodiment (Solid-State Imaging Device)>
6 to 10 are schematic configuration diagrams of a solid-state imaging device according to the second embodiment of the present invention.
In the present embodiment, the pixel array is a 2 × 2 square pixel array.
6 shows an arrangement of one form of a 2 × 2 square pixel arrangement used in this embodiment, FIGS. 7A and 7B show cross-sectional structure diagrams of three pixels, and FIG. 8 shows a pixel arrangement of an imaging region. The top view of this and the arrangement | positioning of a corresponding dichroic prism are shown. FIG. 9 shows a plan view of one form of the arrangement of microlenses, and FIG. 10 shows a plan view of another form of the arrangement of microlenses.

  The solid-state imaging device of the present embodiment employs a 2 × 2 square pixel array shown in FIG. That is, with 2 × 2 4 pixels as one unit, a blue B pixel is arranged in the vertical direction of the green G pixel, a red R pixel is arranged in the horizontal direction of the green G pixel, and the remaining one pixel is A white W pixel is assumed. No color filter is disposed on the white W pixel.

The cross-sectional structure diagram of FIG. 7A shows a cross-sectional view in the xz plane that passes through the green G and blue B pixels of FIG. The cross-sectional structure diagram of FIG. 7B shows a cross-sectional view in the yz plane that passes through the green G and red R pixels of FIG.
7A and 7B, the components arranged are the same as in FIG. 1 of the first embodiment, but the orientation of the upper dichroic prism 10 (11, 12) and the lower first The direction of the two-layer dichroic prism 20 (21, 22) is 90 degrees different.
As described above, the orientations of the dichroic prisms 11, 12, 21, and 22 are different from those of the first embodiment, but the dichroic prism through which each of the three colors of light passes is the same as that of the first embodiment. That is, the first layer dichroic prism 10 (11, 12) transmits green G and blue B light, reflects red R light, and guides it to the light receiving unit 1 (R) of the red R pixel. The transmitted green G and blue B light is transmitted by the second layer dichroic prism 20 (21, 22) and reflected by the blue B, so that the light receiving portions 1 (G) and 1 of the respective colors are transmitted. Guided to (B). That is, the configuration is such that incident light is separated into three wavelength bands of red, green, and blue by a combination of a set of four dichroic prisms 11, 12, 21, and 22.
Further, as will be described later in detail (see FIGS. 9 and 10), in the present embodiment, the arrangement of the microlenses 6 is different from that in the first embodiment. Therefore, in FIGS. 7A and 7B, the size of the microlens 6 is about 2 pixels in total, which is the entire center pixel and about half of the left and right pixels with respect to the 3 pixels of FIG.

In the present embodiment, a large number of units are arranged in the imaging region of the solid-state imaging device, with the 2 × 2 four-pixel spectral structure shown in FIG. 6 as one unit.
Then, as shown in the plan view of FIG. 8, the 2 × 2 pixel unit is arranged so as to be symmetric with respect to the center lines C1 and C2 of the imaging region corresponding to the above-described center of the angle of view. That is, it is symmetric with respect to the center line C1 of the imaging region in the x direction (so-called horizontal direction), and symmetric with respect to the center line C2 of the imaging region in the y direction (so-called vertical direction).
The upper left area has the same pixel arrangement as that in FIG. 6. In the upper right area, the lower right area, and the lower left area, the left and right or the upper and lower sides of the pixel arrangement in FIG. Yes. That is, they are arranged so as to be symmetrical with each other in the four quadrants.
In FIG. 8, the positions of the three colors R, G, and B in the plan view do not correspond to the positions of the surrounding dichroic prisms 11, 12, 21, and 22. Actually, as shown in FIGS. 7A and 7B, the dichroic prism 11 and the dichroic prism 21 are arranged in the green G pixel, the dichroic prism 12 is arranged in the red R pixel, and the dichroic prism 22 is blue B. Arranged in the pixel.

The arrangement of a set of four dichroic prisms 11, 12, 22, and 21 is the same as that in FIG. 7B for the pixels on the left side of the center line C1 of the imaging region, and for the pixels on the right side of the center line C1, FIG. The direction is the opposite of 7B. Further, the pixels on the lower side of the center line C2 have the same orientation as FIG. 7A, and the pixels on the upper side of the center line C2 have the opposite orientation to FIG. 7A.
The upper dichroic prisms 11 and 12 including the dichroic prism 11 on which the incident light first enters are arranged so that the reflecting surfaces of the dichroic mirrors 4A and 4B face the center line C1. . The lower second dichroic prisms 21 and 22 are arranged such that the reflecting surfaces of the dichroic mirrors 4C and 4D face the center line C2.

  Note that it is also possible to dispose the lower dichroic prisms 21 and 22 in the second embodiment so that the reflecting surfaces of the dichroic mirrors 4C and 4D face the side opposite to the center line C2. is there. In the case of this arrangement, the G and R rows are adjacent to the center line C2 by reversing the G and R rows and the B and W rows from the arrangement shown in FIG. Should be arranged.

  In the present embodiment, since pixels of the same color are not formed in stripes, the dichroic prisms 11, 12, 21, and 22 are formed separately for each pixel in the x direction and the y direction.

  Of the four dichroic prisms 11, 12, 21, and 22 in one unit, the two dichroic prisms 12 and 22 that only reflect light and do not transmit light are used instead of the dichroic mirrors 4B and 4D. A simple reflection mirror may be used. For example, a reflection mirror made of a metal film (Al film or the like) or an alloy film can be used.

Next, one form of arrangement | positioning of the micro lens 6 of the solid-state image sensor of this Embodiment is shown in FIG. In the arrangement shown in FIG. 9, the substantially square microlenses 6 are arranged with the green G pixel at the center and half of the left and right red R pixels and half of the front and rear blue B pixels.
This form shows the arrangement of the microlenses 6 when the white W pixels are not used for imaging. Therefore, the four front and rear microlenses 6 are gathered on the white W pixel.
In this case, since the light is focused on the green G pixel, there is no incident light on the white W pixel, and therefore no light receiving portion is required for the white W pixel, and spectral information of three colors of red, blue, and green Signal processing can be performed only with this.
FIG. 9 shows the arrangement of the microlenses 6 of the pixels in the upper left region, which is divided by the center line C1 and the center line C2, in the imaging region of FIG. In the upper right area, the lower right area, and the lower left area of the imaging area in FIG. 8, the color arrangement of the pixels under the microlens 6 is changed from the arrangement in FIG. 9 corresponding to FIG.

FIG. 10 shows another form of arrangement of the microlenses 6 of the solid-state imaging device of the present embodiment. In the arrangement shown in FIG. 10, the substantially square microlenses 6 are arranged obliquely with the green G pixel and the white W pixel as the centers so that the diagonal line is in the front-rear and left-right directions.
This form shows the arrangement of the microlenses 6 when white W pixels are used for imaging. For this reason, the microlenses 6 are arranged around the green G pixel and the white W pixel, respectively, and four microlenses 6 are gathered on the red R and blue B pixels, respectively.
In this case, the light is condensed on the green G pixel and the white W pixel, and the white luminance information and the red / green / blue spectral information are signal-processed to output an image. When the arrangement of FIG. 10 is compared with the arrangement of FIG. 9, if the pixel size is the same, the spatial resolution is high.
FIG. 10 shows the arrangement of the microlenses 6 of the pixels in the upper left area divided by the center line C1 and the center line C2 in the imaging area of FIG. In the upper right area, the lower right area, and the lower left area of the imaging area in FIG. 8, the color arrangement of the pixels under the microlens 6 is changed from the arrangement in FIG. 10 corresponding to FIG.

  According to the configuration of the solid-state imaging device of the present embodiment described above, the orientations of the reflecting surfaces of the dichroic mirrors 4A, 4B, 4C, and 4D of the dichroic prisms 11, 12, 21, and 22 are the center lines C1 and C2 of the imaging region. They are arranged symmetrically. For this reason, in the pixels on both sides of the center lines C1 and C2, the incident angle of the incident light on the reflecting surface can be made symmetric with respect to the center lines C1 and C2. Accordingly, it is possible to suppress the difference in spectral characteristics between the pixels on both sides of the center lines C1 and C2 with respect to the obliquely incident light, and it is possible to suppress the occurrence of color unevenness due to the difference in spectral characteristics. .

  Further, color filters 2R, 2G, and 2B are disposed on the light receiving unit 1 below the dichroic prisms 11, 12, 21, and 22. For this reason, the color filters 2R, 2G, and 2B can correct the dispersion due to tolerances at the time of manufacturing the multilayer film of the dichroic mirrors 4A, 4B, 4C, and 4D, and the spectral characteristics changed due to the change in the incident angle. Thereby, it is possible to improve the color purity by aligning the spectral characteristics of the pixels. Further, even if the number of layers of the multilayer film is reduced, the transmission band widened by the reduction can be corrected by the color filters 2R, 2G, and 2B, so that sufficient color purity can be realized.

According to the present embodiment, as described above, it is possible to suppress the occurrence of color unevenness due to the difference in spectral characteristics, and the color characteristics deformed by the incident angle and manufacturing tolerances are corrected by the color filter. Purity can be improved.
As a result, a solid-state imaging device excellent in color reproducibility and incident angle dependency can be realized, and an image having sufficient color purity and good image quality can be obtained.

Further, since the spectral method using both the dichroic prisms 11, 12, 21, and 22 and the color filters 2R, 2G, and 2B is adopted, it is possible to increase the light utilization efficiency compared to the spectral method using only the color filter. is there.
Further, by giving the color filter the role of controlling the spectral characteristics, the color purity can be increased without increasing the number of layers of the dichroic mirrors 4A, 4B, 4C, and 4D.

Furthermore, according to the present embodiment, the upper dichroic prisms 11 and 12 including the dichroic prism 11 on which the incident light is first incident, the reflecting surfaces of the dichroic mirrors 4A and 4B are center lines of the imaging region. It arrange | positions so that it may face the C1 side.
As a result, when light is incident on the solid-state imaging device obliquely, the change in the spectral characteristics of the dichroic mirror 4A of the dichroic prism 11 is widened in both pixels on the center line C1. Can do.
Accordingly, it is possible to prevent a decrease in sensitivity due to oblique incidence on the solid-state imaging device, and to improve color purity and sensitivity.

<4. Third Embodiment (Solid-State Imaging Device)>
The schematic block diagram of the solid-state image sensor of the 3rd Embodiment of this invention is shown in FIGS.
In the present embodiment, the pixel array is a stripe pixel array in which three colors of R / G / B are arranged in the x direction and the spectrum is split by a single layer dichroic prism.
FIG. 11 shows a cross-sectional structure diagram for six pixels, and FIG. 12 shows a plan view of the pixel arrangement in the imaging region and the arrangement of the corresponding dichroic prism. 13 shows a plan view of one form of the arrangement of microlenses, and FIG. 14 shows a plan view of another form of the arrangement of microlenses.

As shown in FIG. 11, the solid-state imaging device of the present embodiment is provided with three dichroic prisms 13, 14, and 15 arranged in the same layer on the color filters 2B, 2G, and 2R. In each of the dichroic prisms 13, 14, and 15, dichroic mirrors 4E, 4F, and 4G made of multilayer films are formed on the surface on which light is incident.
In the solid-state imaging device according to the present embodiment, a frame indicated by a bold line in FIG. 11 is a basic unit. A set of three dichroic prisms 13, 14, 15 and three pixels below the basic unit are arranged side by side in the x direction.

In the solid-state imaging device of the present embodiment, incident light is collimated by collimating lens 5 by condensing light for three pixels of R / G / B on the upper side of green G pixel by micro lens 6. Refract to light.
The blue B and red R light is reflected by the dichroic prism 13 disposed in the green G pixel, and the green G light is transmitted and guided to the light receiving unit 1 (G) of the green G pixel. That is, the dichroic mirror 4E of the dichroic prism 13 has a characteristic of transmitting green G light and reflecting blue B and red R light.
Next, the red R light is transmitted by the dichroic prism 14 arranged in the blue B pixel, and the blue B light is reflected and guided to the light receiving unit 1 (B) of the blue B pixel. That is, the dichroic mirror 4F of the dichroic prism 14 has a characteristic of reflecting blue B light and transmitting red R light.
Further, the dichroic prism 15 disposed in the red R pixel reflects the red R light and guides it to the light receiving unit 1 (R) of the red R pixel. That is, the dichroic mirror 4G of the dichroic prism 15 has a characteristic of reflecting red R light.

In this embodiment, a large number of units are arranged in the imaging region of the solid-state imaging device, with the spectral structure for three pixels indicated by the bold frame in FIG. 11 as one unit.
Then, as shown in the plan view of FIG. 12, pixels of the same color are arranged in stripes in the y direction (so-called vertical direction). In the x direction (so-called horizontal direction), pixels of three colors R, G, and B are arranged symmetrically with respect to the center line C of the imaging region corresponding to the above-described center of the angle of view. These points are the same as in the first embodiment.
However, as can be seen by comparing the cross-sectional structure diagrams of FIG. 1 and FIG. 11, the arrangement order of the pixels of the three colors R, G, B is different, and the three-color R is also shown in the plan views of FIGS. , G, B pixels are arranged in a different order.
The dichroic prisms 13, 14, and 15 are arranged so as to be symmetric with respect to the center line C of the imaging region in the x direction, as schematically shown in the upper diagram of FIG.
In FIG. 12, the positions of the three color R, G, and B pixels in the plan view in the lower diagram and the positions of the dichroic prisms 13, 14, and 15 in the upper diagram do not correspond vertically. In practice, as shown in FIG. 11, the dichroic prism 13 is arranged in the green G pixel, the dichroic prism 14 is arranged in the blue B pixel, and the dichroic prism 15 is arranged in the red R pixel.

The arrangement of a set of three dichroic prisms 13, 14, and 15 is the same as that of FIG. 11 for the pixels on the left side of the center line C in the imaging region, and for the pixels on the right side of the center line C, FIG. Is in the opposite direction.
A set of three dichroic prisms 13, 14, and 15 including the dichroic prism 13 on which incident light first enters are arranged so that the reflecting surfaces of the dichroic mirrors 4 D, 4 E, and 4 F are directed toward the center line C. Has been.

In the present embodiment, since pixels of the same color are arranged in a stripe shape in the y direction, the dichroic prisms 13, 14, and 15 do not need to be separated for each pixel in the y direction.
Therefore, similarly to FIG. 3 of the first embodiment, the dichroic prisms 13, 14, and 15 can be formed in a continuous shape in the y direction. Thereby, compared with the case where the y direction of the dichroic prism is also separated for each pixel, the manufacturing process of the dichroic prisms 13, 14, and 15 can be simplified and manufactured more easily.

  Of the set of three dichroic prisms 13, 14, and 15, the dichroic prism 15 that only reflects light and does not transmit light may use a simple reflecting mirror instead of the dichroic mirror 4F. . For example, a reflection mirror made of a metal film (Al film or the like) or an alloy film can be used.

Next, FIG. 13 shows one form of arrangement of the microlenses 6 of the solid-state imaging device of the present embodiment. In the arrangement shown in FIG. 13, the shapes of the pixels and the microlenses 6 are the same as those in FIG. 4, but the order of arrangement of the pixel colors and the positions of the microlenses 6 are different from those in FIG. 4. The microlens 6 is arranged on three pixels arranged in a row from the left, a red R pixel, a green G pixel, and a blue B pixel. As shown on the left side of the center line C in FIG. 12, the pixels are arranged in green G, blue B, and red R from the left, so that the position of the micro lens 6 is shifted to the left by one pixel.
FIG. 13 shows the arrangement of the microlenses 6 of the pixels on the left side of the center line C in the imaging region of FIG. In the pixel on the right side of the center line C of the imaging region in FIG. 12, the microlens is placed on the three pixels arranged in the order of the blue B pixel, the green G pixel, and the red R pixel from the left, contrary to FIG. 6 is arranged. Further, the position of the micro lens 6 is shifted to the right by one pixel.
Since the microlenses 6 are arranged in this way, in the imaging region of FIG. 12, the red R pixels in the left and right columns of the center line C may not have the microlenses 6 on the upper side.

FIG. 14 shows another form of arrangement of the microlenses 6 of the solid-state imaging device of the present embodiment. In the arrangement shown in FIG. 14, the shapes of the pixels and the microlenses 6 are the same as those in FIG. 5, but the order of arrangement of the pixel colors and the positions of the microlenses 6 are different from those in FIG. 5. The microlens 6 is arranged on three pixels arranged in a row from the left, a red R pixel, a green G pixel, and a blue B pixel. As shown on the left side of the center line C in FIG. 12, the pixels are arranged in green G, blue B, and red R from the left, so that the position of the micro lens 6 is shifted to the left by one pixel.
14 shows the arrangement of the microlenses 6 of the pixels on the left side of the center line C in the imaging region of FIG. In the pixel on the right side of the center line C in the imaging region of FIG. 12, the microlens is placed on the three pixels arranged in the order of the blue B pixel, the green G pixel, and the red R pixel from the left, contrary to FIG. 6 is arranged. Further, the position of the micro lens 6 is shifted to the right by one pixel.
Since the microlenses 6 are arranged in this way, in the imaging region of FIG. 12, the red R pixels in the left and right columns of the center line C may not have the microlenses 6 on the upper side.

  Other configurations are the same as those of the first embodiment shown in FIGS.

  According to the configuration of the solid-state imaging device of the present embodiment described above, the dichroic mirrors 4E, 4F, and 4G of the dichroic prisms 13, 14, and 15 are arranged so that the reflection surfaces thereof are symmetrical with respect to the center line C of the imaging region. Has been. For this reason, in the pixels on both sides of the center line C, the incident angle of the incident light on the reflecting surface can be made symmetric with respect to the center line C. Accordingly, it is possible to suppress the difference in spectral characteristics between the pixels on both sides of the center line C with respect to the obliquely incident light, and it is possible to suppress the occurrence of color unevenness due to the difference in spectral characteristics.

  In addition, color filters 2R, 2G, and 2B are disposed on the light receiving unit 1 below the dichroic prisms 13, 14, and 15, respectively. Therefore, the color filters 2R, 2G, and 2B can correct the dispersion due to tolerance at the time of manufacturing the multilayer film of the dichroic mirrors 4E, 4F, and 4G, and the spectral characteristics changed due to the change in the incident angle. Thereby, it is possible to improve the color purity by aligning the spectral characteristics of the pixels. Further, even if the number of layers of the multilayer film is reduced, the transmission band widened by the reduction can be corrected by the color filters 2R, 2G, and 2B, so that sufficient color purity can be realized.

According to the present embodiment, as described above, it is possible to suppress the occurrence of color unevenness due to the difference in spectral characteristics, and the color characteristics deformed by the incident angle and manufacturing tolerances are corrected by the color filter. Purity can be improved.
As a result, a solid-state imaging device excellent in color reproducibility and incident angle dependency can be realized, and an image having sufficient color purity and good image quality can be obtained.

In addition, since the spectral method using both the dichroic prisms 13, 14, and 15 and the color filters 2R, 2G, and 2B is employed, it is possible to increase the light use efficiency as compared with the spectral method using only the color filter.
By giving the color filter the role of controlling the spectral characteristics, the color purity can be increased without increasing the number of layers of the dichroic mirrors 4E, 4F, 4G.

Furthermore, according to the present embodiment, a set of three dichroic prisms 13, 14, and 15 including the dichroic prism 13 on which incident light is first incident, the reflecting surfaces of the dichroic mirrors 4 </ b> D, 4 </ b> E, and 4 </ b> F are imaging regions. It is arrange | positioned so that it may face to the center line C side.
Thereby, when light is incident on the solid-state imaging device obliquely, the change in the spectral characteristics of the dichroic mirror 4D of the dichroic prism 13 is increased in the pixels on both sides of the center line C so that the transmission band width is widened. Can do.
Accordingly, it is possible to prevent a decrease in sensitivity due to oblique incidence on the solid-state imaging device, and to improve color purity and sensitivity.

  Furthermore, in the present embodiment, since the dichroic mirrors 13, 14, and 15 are arranged in only one layer, the light receiving unit 1 is compared with the configurations of the first and second embodiments. To the microlens 6 can be reduced.

In each of the above-described embodiments, a stripe pixel array or a 2 × 2 square pixel array including white W pixels is employed.
In the solid-state imaging device of the present invention, the pixel arrangement (pixel color arrangement) of the imaging region is not limited to these pixel arrangements, and other pixel arrangements can be adopted.

<5. Fourth Embodiment (Imaging Device)>
FIG. 15 shows a schematic configuration diagram (block diagram) of an imaging apparatus according to the fourth embodiment of the present invention.
Examples of the imaging device include a video camera, a digital still camera, and a mobile phone camera.

As illustrated in FIG. 15, the imaging apparatus 500 includes an imaging unit 501 that includes a solid-state imaging element (not shown). An imaging optical system 502 that focuses incident light and forms an image is provided in the front stage of the imaging unit 501. Further, a signal processing unit 503 having a drive circuit that drives the imaging unit 501, a signal processing circuit that processes a signal photoelectrically converted by the solid-state imaging device, and the like is connected to the subsequent stage of the imaging unit 501. The image signal processed by the signal processing unit 503 can be stored by an image storage unit (not shown).
In such an imaging apparatus 500, the solid-state imaging device of the present invention, such as the solid-state imaging device of each embodiment described above, can be used as the solid-state imaging device.

According to the imaging apparatus 500 of the present embodiment, the solid-state imaging device of the present invention, that is, as described above, sufficient light use efficiency and color purity are obtained, and the color reproducibility and incident angle dependency are excellent. A solid-state image sensor is used.
Accordingly, there is an advantage that the imaging apparatus 500 that can obtain a high-quality image with excellent color reproducibility can be configured even when the incident angle of light on the solid-state imaging element changes obliquely.

Note that the imaging apparatus of the present invention is not limited to the configuration shown in FIG. 15 and can be applied to any imaging apparatus using a solid-state imaging device.
For example, the solid-state imaging device may be in a form formed as a single chip, or in a modular form having an imaging function in which an imaging unit and a signal processing unit or an optical system are packaged together. Also good.
The imaging apparatus of the present invention can be applied to various imaging apparatuses such as a camera and a portable device having an imaging function. The broad meaning of “imaging” includes a fingerprint detection device and the like.

  The present invention is not limited to the above-described embodiment, and various other configurations can be taken without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Light-receiving part, 2B, 2G, 2R Color filter, 3 Inter-pixel light-shielding part, 4A, 4B, 4C, 4D, 4E, 4F, 4G Dichroic mirror, 5 Collimate lens, 6 Micro lens, 10 First layer dichroic prism, 11, 12, 13, 14, 15, 21, 22 Dichroic prism, 20 Second layer dichroic prism, 500 imaging device, 501 imaging unit, 502 imaging optical system, 503 signal processing unit

Claims (10)

A light receiving portion provided in each pixel and subjected to photoelectric conversion;
A dichroic mirror is formed on one surface by a multilayer film, and is provided above the light receiving unit. A plurality of dichroic mirrors are formed as one set, and incident light is separated into light of a plurality of wavelength bands by the plurality of combinations. A dichroic prism having a structure in which light in each wavelength band is incident on the light receiving unit of a different pixel, and the dichroic mirror is arranged so that the direction of the reflection surface is symmetric with respect to the center line of the imaging region;
A solid-state imaging device including a color filter disposed below the dichroic prism and on the light receiving unit.   2. The dichroic prism into which at least the incident light first enters among the set of the plurality of dichroic prisms is disposed so that the reflecting surface faces a center line side of the imaging region. The solid-state imaging device described.   The solid-state imaging device according to claim 1, further comprising a light shielding material formed between the light receiving portions of the adjacent pixels.   The set of a plurality of dichroic prisms is a total of four dichroic prisms, two in each of two upper and lower layers. Among the four dichroic prisms, two dichroic prisms including the dichroic prism on which the incident light enters first are included. The solid-state imaging device according to claim 2, wherein the dichroic prism is arranged so that the reflection surface faces a center line side of the imaging region.   The set of the plurality of dichroic prisms are three dichroic prisms formed in the same layer, and the three dichroic prisms are arranged so that the reflecting surface faces the center line side of the imaging region. The solid-state imaging device according to claim 2, wherein A condensing optical unit that condenses incident light;
A light receiving portion provided in each pixel, where photoelectric conversion is performed, and a dichroic mirror formed of a multilayer film on one surface. The light receiving portion is provided above the light receiving portion. The incident light is separated into light of a plurality of wavelength bands by combination, and the light of each wavelength band is incident on the light receiving unit of different pixels, and the direction of the reflection surface of the dichroic mirror is the center line of the imaging region A solid-state imaging device including a dichroic prism disposed so as to be symmetric, and a color filter disposed below the dichroic prism and on the light receiving unit,
A signal processing unit that processes a signal obtained by photoelectric conversion by the solid-state imaging device;   Of the dichroic prisms in the set of the solid-state imaging device, at least the dichroic prism on which the incident light first enters is disposed so that the reflecting surface faces the center line side of the imaging region. The imaging device according to claim 6.   The imaging device according to claim 6, wherein the solid-state imaging device further includes a light shielding material formed between the light receiving portions of the adjacent pixels.   The set of the plurality of dichroic prisms of the solid-state imaging device includes a total of four dichroic prisms, two in each of two upper and lower layers, and includes a dichroic prism on which the incident light first enters among the four dichroic prisms. The imaging apparatus according to claim 7, wherein the two upper dichroic prisms are arranged such that the reflecting surface faces a center line side of the imaging region. The set of the plurality of dichroic prisms of the solid-state imaging device is three dichroic prisms formed in the same layer, and the three dichroic prisms have a reflecting surface on the side of the center line of the imaging region. The imaging device according to claim 7, wherein the imaging device is disposed so as to face the camera.