JP2008112944A - Solid-state image sensor - Google Patents

Abstract

A solid-state imaging device capable of suppressing color mixing caused by light leaking from adjacent pixels is provided.
SOLUTION: A sensor unit 11 that performs photoelectric conversion and a light shielding layer 17 provided between a color filter 15 corresponding to the sensor unit 11, and the light shielding layer 17 extends along the pixel separation unit. 11 is a solid-state imaging device that is formed perpendicularly or substantially perpendicularly to 11.
[Selection] Figure 1

Description

  The present invention relates to a solid-state imaging device provided with a light shielding layer for blocking light leaking from adjacent pixels.

  In a solid-state imaging device used for an image sensor or the like, incident light is collected on a sensor unit including a photodiode of each pixel, and further photoelectrically converted into a signal.

Since the sensor unit made of a photodiode has sensitivity in the entire visible light wavelength range, color information cannot be obtained as it is.
Therefore, in the color solid-state imaging device, a color filter, for example, a filter corresponding to each color of red, green, and blue is provided in each pixel.

The most common color arrangement of the color filter is a Bayer arrangement in which 4 cells of 2 × 2 are one red cell, one blue cell, and two green cells.
As another color arrangement, there are, for example, an arrangement in which four 2 × 2 cells are divided into four colors of cyan, yellow, magenta, and green using a so-called complementary color filter.
Each pure color can be obtained by calculating and correcting a signal obtained through the color filter of each color by a correction algorithm.

  A normal color filter is made of a special organic material having appropriate absorption and transmission characteristics. For example, a resist containing a pigment can be used.

When a color filter is used, there is a problem that the color filter is not a perfect wavelength filter. For example, not all light entering a red cell is red light.
Therefore, the correction algorithm is devised so that a purer color can be demodulated from the input from the color filter of each color. Also, the overlap of spectral characteristics of the color filters of each color can be utilized to help infer pure colors, so that a constant mixing result is provided even under various conditions in which the image sensor is used. .

Further, the semiconductor has absorption sensitivity to infrared light. For this reason, an infrared cut filter for removing infrared light without blocking visible light is usually provided in a solid-state imaging device using a Si semiconductor. This infrared cut filter is usually provided outside the solid-state imaging device, and one infrared cut filter is provided in common for all pixels.
On the other hand, a configuration has been proposed in which pixels that detect infrared light are provided to enhance and assist image signals obtained from pixels that detect visible light. In this configuration, instead of providing an infrared cut filter outside, a built-in infrared cut filter is provided in a pixel that detects visible light (see, for example, Patent Document 1).

  FIG. 7 is a schematic configuration diagram (cross-sectional view) of a solid-state imaging device having no built-in infrared cut filter in a conventional CMOS image sensor. FIG. 8 is a schematic configuration diagram (cross-sectional view) of a solid-state imaging device having a built-in infrared cut filter.

The solid-state imaging device shown in FIGS. 7 and 8 includes color pixels 60 and 80 corresponding to light of each color of red R, green G, and blue B, and white corresponding to all light such as visible light and infrared light. Pixels 70 and 90 are formed.
In these color pixels 60, 80 and white pixels 70, 90, sensor units 61, 71, 81, 91 that perform photoelectric conversion corresponding to received light on the silicon substrate, and sensor units 61, 71, Optical coupling layers 62, 72, 82 and 92 formed on 81 and 91 are formed.

  Wiring layers 69 and 89 are formed in portions of the pixels except for the sensor portions 61, 71, 81, and 91. In addition, insulating layers 64, 74, 84, and 94 are provided on the sensor units 61, 71, 81, 91 and the optical coupling layers 62, 72, 82, 92. The wiring layer is formed by providing one or more wirings, and an insulating layer is provided so as to cover the wirings.

  Then, above the optical coupling layers 62, 72, 82, 92, the light incident on the pixels is collected in the sensor units 61, 71, 81, 91 via the insulating layers 64, 74, 84, 94. In order to emit light, two layers of inner lenses 63, 73, 83, 93 are formed.

In the configuration shown in FIG. 8, in the color pixel 80, an infrared cut filter 88 is formed between the sensor unit 81 and the intralayer lens 83 via the insulating layer 84.
In the white pixel 90, since all wavelengths including visible light and infrared light are used, no infrared cut filter is provided.

Color filters 65 and 85 corresponding to the colors of red R, green G and blue B are formed on the insulating layers 64 and 84 of the color pixels 60 and 80, respectively. White filters 75 and 95 that transmit visible light, infrared light, and the like are formed on the insulating layers 74 and 94 of the white pixels 70 and 90, respectively.
Although there is no filter named white filter, in order to simplify the description, a layer that transmits both visible light and infrared light is hereinafter referred to as a “white filter”.
On-chip lenses 66, 76, 86, and 96 having curved surfaces whose upper surfaces are convex upward are formed above the color filters 65 and 85 and the white filters 75 and 95.

  As shown in FIG. 7, the light beam 101 having a large incident angle incident on the white pixel 70 enters the sensor unit 61 of the color pixel 60 beyond the pixel separation unit. For this reason, light leaking from the white pixel 70 adjacent to the light in the color pixel 60 enters the sensor unit 61, and color mixing occurs in the color pixel 60. In addition, since some of the light rays 100 incident on the color pixel 60 do not reach the sensor unit 61, the actual sensitivity of the color pixel 60 decreases.

Further, as shown in FIG. 8, in a solid-state imaging device using an infrared cut filter in color pixels, an infrared cut filter 88 must be provided for each color pixel.
Further, the infrared cut filter 88 is formed with a certain thickness by stacking a plurality of materials such as dielectrics having different refractive indexes. For this reason, the entire thickness of the structure of the solid-state imaging device using the infrared cut filter 88 is increased by the thickness of the infrared cut filter 88.

  By providing the infrared cut filter 88, the overall thickness increases, so the distance from the on-chip lenses 86, 96 to the sensor units 81, 91 increases. For this reason, the occurrence of color mixing due to the light beam 103 leaking from the adjacent white pixel 90 increases. In addition, the light beam 102 leaks from the color pixel 80 to the adjacent white pixel 90, thereby reducing the actual sensitivity of the color pixel 80.

As shown in FIGS. 7 and 8, light beams 101 and 103 having a large incident angle leak to adjacent pixels from one pixel. In the case of the solid-state imaging device shown in FIGS. 7 and 8, the central color pixels 60 and 80 are pixels having any of RGB colors, and the adjacent white pixels 70 and 90 are not only visible light. This is a pixel corresponding to all wavelengths including infrared light.
Therefore, if the incident angle of light incident on the white pixels 70 and 90 is large, all wavelengths including visible light and infrared light incident on the white pixels 70 and 90 leak into the red color pixels 60 and 80. This makes it difficult to reproduce accurate colors in the color pixels 60 and 80 even when correction is performed by signal processing by calculation for all three primary colors from the three color filters of RGB.

For this reason, in order to suppress the occurrence of color mixing, it has been proposed to form a waveguide structure above the sensor part by inserting materials having different refractive indexes above the sensor part of each pixel ( For example, see Patent Document 2 and Patent Document 3).
By forming a waveguide structure, even when light having a large incident angle is incident on each pixel, reflection by utilizing the difference in refractive index in the waveguide structure prevents leakage of adjacent light. be able to.

JP 2006-190958 A Special table 2003-517635 gazette US Pat. No. 6,861,686

However, in order to form a solid-state imaging device having the above-described waveguide structure, it is necessary to embed a material having a high refractive index in the hole after forming a deep hole in the insulating layer.
For this reason, as the pixels are miniaturized, the aspect ratio of the hole (ratio of width to height) increases, making it difficult to drill holes and embed materials.
Moreover, since it is necessary to add a process for forming the waveguide structure, it is difficult to realize commercially from the viewpoint of production efficiency and cost.

  Further, when a waveguide structure is applied to a solid-state imaging device having a built-in infrared cut filter, it is necessary to perform a step of forming a built-in infrared cut filter and a step of forming a waveguide structure, The process becomes complicated, and it is difficult to realize commercially because of production efficiency and cost.

  As described above, in a solid-state imaging device, it is very difficult to have a structure that suppresses color mixture by removing light leaking from adjacent pixels before reaching the sensor unit.

  In order to solve the above-described problem, the present invention provides a solid-state imaging device capable of suppressing color mixing caused by light leaking from adjacent pixels.

  The solid-state imaging device of the present invention includes a pixel including a sensor unit that performs photoelectric conversion, a color filter corresponding to the sensor unit, and a light shielding layer, and the light shielding layer is disposed between the sensor unit and the color filter. It is provided in the pixel, and is formed perpendicularly or substantially perpendicular to the sensor part along the pixel separation part.

In the solid-state imaging device of the present invention, a light shielding layer is formed vertically or substantially vertically along the pixel separation portion between the sensor portion and the color filter. In the solid-state imaging device of the present invention, the substantially vertical angle at which the light shielding layer is formed includes a range of inclination from vertical to about 10 degrees with respect to the sensor unit.
Thereby, even when light leaks from an adjacent pixel, the light that leaks can be blocked by the light shielding layer above the sensor unit.
In addition, by providing a light shielding layer below the color filter, light having a specific color that has passed through the color filter can be blocked by the light shielding layer.

  According to the configuration of the solid-state imaging device of the present invention described above, by having the light shielding layer in the pixel, it is possible to prevent light from adjacent pixels from leaking and to prevent color mixing.

FIG. 1 shows a schematic configuration diagram (cross-sectional view) of the solid-state imaging device according to the first embodiment of the present invention.
FIG. 1 shows a case where the present invention is applied to a CMOS type solid-state imaging device.

The solid-state imaging device according to the first embodiment includes a color pixel 10 corresponding to light of each color of red R, green G, and blue B, and a white pixel 20 corresponding to all light such as visible light and infrared light. Formed from.
In the color pixel 10 and the white pixel 20, on the silicon substrate, sensor units 11 and 21 that perform photoelectric conversion in response to received light, and optical coupling layers 12 and 12 formed on the sensor units 11 and 21, 22 is formed.

Although not shown, each of the sensor units 11 and 21 includes a first conductivity type, for example, an n-type semiconductor region, and a photodiode is configured by a second conductivity type, for example, a p-type semiconductor region formed on the silicon substrate.
Although not shown, between the sensor units 11 and 21 of each pixel, for example, a second conductivity type (p-type) element isolation region is formed, so that adjacent pixels are separated.

  A wiring layer 19 is formed in a portion other than the sensor portions 11 and 21 of each pixel. Insulating layers 14 and 24 are provided on the sensor portions 11 and 21 and the optical coupling layers 12 and 22. Although the wiring layer is not shown, one or two or more wirings are provided, and an insulating layer is provided so as to cover the wiring, but this is shown in a simplified manner in this drawing.

In the color pixel 10, a light shielding layer 17 is formed via an insulating layer 14.
The light shielding layer 17 exists in the color pixel 10 and is formed substantially perpendicular to the sensor unit 11 along the element isolation unit.
In addition, two layers of intralayer lenses 13 are formed on the light shielding layer 17 of the color pixel 10 to collect light incident on the pixel through the insulating layer 14 onto the sensor unit 11. In addition, in the insulating layer 24 of the white pixel 20, two layers of the inner lens 23 are formed in order to collect the light incident on the pixel on the sensor unit 21.

A color filter 15 corresponding to each color of red R, green G, and blue B is formed on the insulating layer 14 of the color pixel 10. A white filter 25 that transmits visible light, infrared light, and the like is formed on the insulating layer 24 of the white pixel 20.
On-chip lenses 16 and 26 having curved surfaces whose upper surfaces are convex upward are formed above the color filter 15 and the white filter 25.

  The white filter 25 provided in the white pixel 20 only needs to pass components of all wavelengths including visible light and infrared light, and has a configuration without a color filter or a configuration with a transparent filter. There may be.

By using the white filter 25 to detect all light including visible light and infrared light, the sensor unit 21 obtains an image by infrared light or an image in which infrared light and visible light are mixed. Can do. Moreover, a color image by visible light can be obtained by detecting with the corresponding sensor part 11 through the color filter 15 of each color.
For this reason, it is possible to image from both infrared light and visible light, and real sensitivity can be increased. Moreover, although the image imaged from both infrared light and visible light is obtained, the image of only infrared light is obtained by taking the difference of both.

The optical coupling layers 12 and 22 are made of, for example, SiN or SiON, and have a refractive index between the refractive index of the material forming the insulating layers 14 and 24 and the refractive index of the material forming the sensor units 11 and 21. It is formed of a material having a refractive index.
The optical coupling layers 12 and 22 are configured such that the light collected by the on-chip lenses 16 and 26 and the in-layer lenses 13 and 23 passes through the insulating layers 14 and 24 and passes from the insulating layers 14 and 24 to the sensor units 11 and 24. This is provided in order to reduce the difference between the refractive index of the insulating layers 14 and 24 and the refractive index of the sensor units 11 and 21 when entering the light source 21.

The light shielding layer 17 described above is formed by laminating one or more layers of a metal having a high reflectance in the visible light region or a metal having a high absorption rate.
Various kinds of metals can be used for the light shielding layer 17 according to the use situation and the required reflectance or absorption rate.

As a metal having a high reflectance in the visible light region, for example, a metal such as Ag, Rh, Pt, Mg, Al, Cu, or Au can be used.
By forming the light shielding layer 17 with a metal having a high reflectance, the light beam 50 that has passed through the color filter 15 leaks from the on-chip lens 16 of the color pixel 10 into the adjacent white pixel 20 through the insulating layer 14. Even in this case, the light is reflected by the light shielding layer 17. As a result, the light beam 50 can reach the sensor unit 11 in the original color pixel 10.
Further, when the light beam 51 incident on the adjacent white pixel 20 passes through the on-chip lens 26 and leaks to the color pixel 10 side, it is reflected by the light shielding layer 17. Thereby, the light beam 51 can reach the sensor unit 21 in the original white pixel 20.

At this time, the light shielding layer 17 is perpendicular to the sensor unit 11 or has a shape slightly inclined from the vertical so that the light incident side is narrow and the sensor unit 11 side is wide as shown in FIG. Form.
By forming the light shielding layer 17 with a shape slightly inclined from the vertical, for example, by tilting by about 7 degrees, the light rays 51 leaking from the adjacent white pixels 20 are contained in the original white pixel 20 as compared with the case where the light shielding layer 17 is vertical. It is easy to reach the sensor unit 21. Further, the light beam 50 leaking from the color pixel 10 to the adjacent white pixel 20 is reflected by the light shielding layer 17 and easily reaches the sensor unit 11.

For this reason, by using a metal having a high reflectance for the light shielding layer 17, it is possible to suppress the light incident in the color pixel 10 from leaking to the adjacent white pixel 20 and to enter the adjacent white pixel 20. Light can be prevented from leaking into the color pixel 10. Thereby, the incident light can efficiently reach the sensor units 11 and 21, and the sensitivity of the solid-state imaging device can be improved.
Moreover, since it can suppress that the light which passed the color filter 15 leaks to the sensor part 21 of the adjacent white pixel 20, generation | occurrence | production of color mixing can be suppressed.

In particular, since the white pixel 20 is provided with a white filter 25 that transmits all wavelengths including visible light and infrared light instead of the color filter 15, the amount of light transmitted through the white filter 25 is reduced by the color filter. More than the amount of light transmitted through 15. For this reason, when the light beam 51 leaks into the sensor unit 11 of the adjacent color pixel 10, a large amount of light reaches the sensor unit 11, and color mixing due to the influence of light leaking from the white pixel 20 is a pixel having a color filter. It becomes larger than the influence of light leaking from.
However, by providing the above-described configuration, light leaking from the adjacent white pixels 20 can be reflected by the light shielding layer 17, so that color mixing can be suppressed.

Moreover, even if the metal used for the light shielding layer 17 is a metal having a low reflectance in the visible light region, any metal having a high absorptance can be used.
This is because, in the light shielding layer 17, the light leaking from the adjacent white pixel 20 is absorbed by the light shielding layer 17, so that the light does not reach the sensor unit 11 of the color pixel 10, so This is because no occurrence occurs.

As the metal having a high absorption rate in the visible light region, for example, a metal such as Ta, Ti, W or the like can be used.
Moreover, instead of the metal having a high absorption rate, an inorganic material such as Ge or Si having a high absorption rate can be used.
By using a metal having high absorptance in the visible light region, for example, the light beam 50 that has passed through the color filter 15 leaks from the on-chip lens 16 of the color pixel 10 into the adjacent white pixel 20 through the insulating layer 14. Even in this case, it is possible to prevent the white pixel 20 from reaching the sensor unit 21 by being absorbed by the light shielding layer 17.
Further, even when the light beam 51 incident on the adjacent white pixel 20 passes through the on-chip lens 26 and leaks to the color pixel 10 side, the light beam 51 is absorbed by the light shielding layer 17 and thereby enters the sensor unit 11 of the color pixel 10. Reach can be prevented.

The thickness of the light shielding layer 17 varies depending on the metal material used, but in order to reflect or absorb light incident on the light shielding layer 17, it is preferably 20 nm or more and 50 nm or less.
When the thickness of the light shielding layer 17 is less than 20 nm, the amount of light that passes through the light shielding layer 17 increases, and the effect of the light shielding layer 17 due to reflection or absorption is reduced. Moreover, since the light shielding layer 17 will become thick when the light shielding layer 17 exceeds 50 nm, it becomes difficult to miniaturize the whole device.

As described above, by forming the light shielding layer 17 in the color pixel 10, for example, a light shielding layer is formed on the entire surface of the pixel separation portion of the color pixel 10 and the white pixel 20, and light leaking into adjacent pixels is emitted. The light shielding layer can be made smaller than a structure that reflects light. For this reason, the freedom degree at the time of designing a device improves.
Furthermore, even when the thickness from the sensor portion of the device to the on-chip lens becomes thick, color mixture can be suppressed by reflecting or absorbing light by the light shielding layer 17. For this reason, the degree of freedom of design is improved in device design.
In particular, in the CMOS type solid-state imaging device as shown in FIG. 1, since it is necessary to form a multilayer wiring above the sensor parts 11 and 21, the distance from the sensor part to the on-chip lens tends to be large. However, even when the device becomes thick in this way, the color mixture can be suppressed by the light shielding layer 17.

Although the infrared cut filter is not provided in the solid-state imaging device according to the first embodiment illustrated in FIG. 1, a built-in infrared cut filter may be provided inside the color pixel 10.
The infrared cut filter in this case is provided inside the color pixel 10 and above the light shielding layer 17 or inside the color pixel 10 and provided between the sensor unit 11 and the light shielding layer 17. be able to.
Thereby, the solid-state image sensor in which the built-in infrared cut filter was formed in the color pixel 10 can be comprised.

  Next, the manufacturing method of the solid-state imaging device according to the first embodiment will be described with reference to FIGS.

First, a wiring layer 19 is formed by sequentially forming a wiring and an insulating layer covering the wiring.
Thereafter, as shown in FIG. 2A, the insulating layers 14 and 24 are formed to a height at which the light shielding layer 17 is provided by using a CVD method or the like with SiO ₂ or the like.

  Next, the insulating layers 14 and 24 are etched using a known etching method so that the insulating layer 14 on the sensor portion 11 has a mesa shape as shown in FIG. 2B.

  Next, the entire surface of the insulating layers 14 and 24 is coated with a highly reflective metal in the visible light region, or a metal, semimetal or inorganic material having an absorptance. As a result, as shown in FIG. 2C, the light shielding layer 17 </ b> A is formed on the entire surface of the insulating layers 14 and 24.

  Next, anisotropic etching is performed on the light shielding layer 17A. As a result, as shown in FIG. 3D, the light shielding layer 17A can be etched leaving the portion formed on the side wall of the mesa-shaped insulating layer 14, and the light shielding layer 17 can be formed on the mesa-shaped side wall. it can.

Next, the insulating layers 14 and 24 are formed on the insulating layers 14 and 24 and the light shielding layer 17 by SiO ₂ or the like again using the CVD method or the like.
Thereby, as shown in FIG. 3E, a shape in which the light shielding layer 17 is embedded in the insulating layer 14 can be formed.

  In the etching of the insulating layer 14 shown in FIG. 2B, if the inclination angle of the mesa-shaped side wall is large, the mesa shape is formed in the etching performed in the step shown in FIG. The light shielding layer 17 does not remain on the side wall. For this reason, the inclination angle of the mesa-shaped side wall is preferably about 7 degrees.

  When the light shielding layer 17 is formed perpendicular to the sensor unit 11, the shape of the insulating layer after etching shown in FIG. 2B is not a mesa shape, and the side wall of the convex portion of the insulating layer 14 is vertical. Etching is performed so that Thereby, the light shielding layer 17 can be formed perpendicular to the sensor unit 11.

  Thereafter, in-layer lenses 13 and 23 are formed in the insulating layers 14 and 24 by a UV-SiN film or the like by a known method. Further, after forming one of the RGB color filters 15 and the white filter 25 on the insulating layers 14 and 24, the on-chip lenses 16 and 26 are sequentially formed.

With the above method, the solid-state imaging device of the first embodiment can be manufactured.
According to the manufacturing method described above, the solid having the light shielding layer 17 can be obtained by using a known etching method and a laminating method such as a chemical vapor deposition (CVD) method and a dry etching method that are conventionally used in a semiconductor manufacturing process. An image sensor can be manufactured. For this reason, it is not necessary to use a special process, and a solid-state imaging device can be manufactured by a simple method.

  Next, FIG. 4 shows a schematic configuration diagram (cross-sectional view) of the solid-state imaging device according to the second embodiment of the present invention. FIG. 4 shows a case where the present invention is applied to a CMOS type solid-state imaging device.

The solid-state imaging device according to the second embodiment includes a color pixel 30 corresponding to light of each color of red R, green G, and blue B, and a white pixel 40 corresponding to all light such as visible light and infrared light. Formed from.
In the color pixel 30 and the white pixel 40, sensor units 31 and 41 that perform photoelectric conversion in response to received light on the silicon substrate, and optical coupling layers 32 that are formed on the sensor units 31 and 41, 42 is formed.

Although not shown, the sensor units 31 and 41 are formed of a first conductivity type, for example, an n-type semiconductor region, and a photodiode is configured by a second conductivity type, for example, a p-type semiconductor region formed on the silicon substrate.
Although not shown, between the sensor units 31 and 41 of each pixel, for example, a second conductivity type (p-type) element isolation region is formed, so that adjacent pixels are separated.

  A wiring layer 39 is formed on the portion of each pixel except for the sensor portions 31 and 41. Insulating layers 34 and 44 are provided on the sensor units 31 and 41 and the optical coupling layers 32 and 42. Although the wiring layer is not shown, one or two or more wirings are provided, and an insulating layer is provided so as to cover the wiring, but this is shown in a simplified manner in this drawing.

In the color pixel 30, an infrared cut filter 38 is provided via an insulating layer 34. A light shielding layer 37 that is substantially perpendicular to the sensor unit 31 is formed on the side surface of the infrared cut filter 38 along the element isolation unit.
In addition, two layers of in-layer lenses 33 are formed on the infrared cut filter 38 of the color pixel 30 in order to collect light incident on the pixel through the insulating layer 34 onto the sensor unit 31. In addition, in the insulating layer 44 of the white pixel 40, two layers of the inner lens 43 are formed in order to collect the light incident on the pixel on the sensor unit 41.

Color filters 35 corresponding to the colors of red R, green G, and blue B are formed on the insulating layer 34 of the pixel 30. Further, a white filter 45 that transmits visible light, infrared light, and the like is formed on the insulating layer 44 of the white pixel 40.
On-chip lenses 36 and 46 having curved surfaces whose surfaces are convex upward are formed above the color filter 35 and the white filter 45.

  In addition, the white filter 45 provided in the white pixel 40 should just pass the component of all the wavelengths including visible light and infrared light, and is a structure which does not provide a color filter, or a structure which provides a transparent filter. There may be.

The white filter 45 is used to detect all light including visible light and infrared light by the sensor unit 41, thereby obtaining an image by infrared light or a mixture of infrared light and visible light. be able to. Moreover, a color image by visible light can be obtained by detecting with the corresponding sensor unit 31 through the color filter 35 of each color.
For this reason, it is possible to image from both infrared light and visible light, and the sensitivity can be increased. Moreover, although the image imaged from both infrared light and visible light is obtained, the image of only infrared light is obtained by taking the difference of both.

The optical coupling layers 32 and 42 are made of, for example, SiN or SiON, and have a refractive index between the refractive index of the material forming the insulating layers 34 and 44 and the refractive index of the material forming the sensor units 31 and 41. It is formed of a material having a refractive index.
Then, when the light collected by the on-chip lenses 36 and 46 and the intra-layer lenses 33 and 43 passes through the insulating layers 34 and 44 and enters the sensor units 31 and 41 from the insulating layers 34 and 44. Optical coupling layers 32 and 42 are provided to alleviate the difference between the refractive index of the insulating layers 34 and 44 and the refractive index of the sensor units 31 and 41.

The above-described infrared cut filter 38 is made of, for example, a multilayer film in which transparent dielectric thin films having different refractive indexes selected from Al ₂ O ₃ , TiO ₂ , SiO ₂ , SiN, and the like are alternately stacked. Reflects external light and transmits only visible light.
The infrared cut filter 38 has a mesa-shaped cross-sectional shape.

An optical coupling layer can also be provided between the upper and lower sides of the infrared cut filter 38 and the insulating layer 34. In this case, the optical coupling layer is made of, for example, SiN or SiON, and has a refractive index between the refractive index of the material forming the insulating layers 34 and 44 and the refractive index of the material forming the sensor units 31 and 41. It is formed of a material having a refractive index.
By providing an optical coupling layer between the upper and lower sides of the infrared cut filter 38 and the insulating layer 34, the difference in refractive index between the insulating layer 34 and the infrared cut filter 38 can be reduced.

The light shielding layer 37 provided on the side surface of the infrared cut filter 38 is formed by laminating one or more layers of a metal having a high reflectance in the visible light region or a metal having a high absorption rate.
Various kinds of metals can be used for the light shielding layer 37 according to the use situation and the required reflectance or absorption rate.
Further, by forming a thin film of Ti, Cr or the like between the side surface of the infrared cut filter 38 and the light shielding layer 37, protection for protecting the side surface of the infrared cut filter 38 and the interface with the light shielding layer 37. A film can also be formed.

As a metal having a high reflectance in the visible light region, for example, a metal such as Ag, Rh, Pt, Mg, Al, Cu, or Au can be used.
A light shielding layer 37 is formed on the side surface of the infrared cut filter 38 with a metal having a high reflectance. Thus, even when the light beam 52 that has passed through the color filter 35 from the on-chip lens 36 of the color pixel 30 leaks into the adjacent white pixel 40 through the insulating layer 34, it is reflected by the light shielding layer 37. Therefore, the light beam 52 can reach the sensor unit 31 in the original color pixel 30.
Further, when the light beam 53 incident on the adjacent white pixel 40 passes through the on-chip lens 46 and leaks to the color pixel 30 side, it is reflected by the light shielding layer 37. Thereby, the light beam 53 can reach the sensor unit 41 in the original white pixel 40.

At this time, the side surface of the infrared cut filter 38 is perpendicular to the sensor unit 31 or, as shown in FIG. 4, the infrared cut filter 38 has a narrow mesa on the light incident side and a wide mesa side on the sensor unit 31 side. The shape of the shape is such that the side surface is slightly inclined from the vertical. A light shielding layer 37 is formed along this side surface.
The light shielding layer 37 is formed on the side surface of the infrared cut filter 38 that is slightly inclined from the vertical direction, for example, about 7 degrees, so that the light beam 53 leaking from the adjacent white pixel 40 is contained in the original white pixel 40. It is easy to reach the sensor part 41. Further, the light beam 52 leaking from the color pixel 30 to the adjacent white pixel 40 is reflected by the light shielding layer 37 and easily reaches the sensor unit 31.

For this reason, by using a metal having a high reflectance for the light shielding layer 37, it is possible to suppress the light incident on the pixel from leaking to the adjacent pixel, and to prevent the light incident on the adjacent pixel from leaking. Can be suppressed. Thereby, the incident light can efficiently reach the sensor units 31 and 41, and the sensitivity of the solid-state imaging device can be improved.
Moreover, since it can suppress that the light which passed the color filter 35 leaks to the sensor part 41 of the adjacent white pixel 40, generation | occurrence | production of color mixing can be suppressed.

In particular, since the pixel 40 is provided with a white filter 45 that transmits all wavelengths including visible light and infrared light instead of the color filter 35, the amount of light transmitted through the white filter 45 increases. And when this light leaks to the adjacent sensor part 31, the light quantity which reaches | attains the sensor part 31 becomes more than the light quantity which permeate | transmits the color filter 15. FIG. For this reason, when the light beam 53 leaks into the sensor unit 31 of the adjacent color pixel 30, a large amount of light reaches the sensor unit 31, and color mixing due to the influence of light leaking from the white pixel 40 is a pixel having a color filter. It becomes larger than the influence of light leaking from.
However, by providing the above-described configuration, light leaking from the adjacent white pixels 20 can be reflected by the light shielding layer 37, so that color mixing can be suppressed.

Moreover, even if the metal used as the light shielding layer 37 formed on the side surface of the infrared cut filter 38 is a metal having a low reflectance in the visible light region, any metal having a high absorptance can be used.
This is because light leaking from adjacent pixels is absorbed by the light shielding layer 37 having a high absorption rate on the side surface of the infrared cut filter. For this reason, light leaking from the adjacent white pixel 40 does not reach the sensor unit 31 of the color pixel 30, and color mixing does not occur in the sensor unit 31 of the color pixel 30.

As the metal having a high absorption rate in the visible light region, for example, a metal such as Ta, Ti, W or the like can be used.
Moreover, instead of the metal having a high absorption rate, an inorganic material such as Ge or Si having a high absorption rate can be used.
By using a metal having high absorptance in the visible light region, for example, the light beam 52 that has passed through the color filter 35 leaks from the on-chip lens 36 of the color pixel 30 into the adjacent white pixel 40 through the insulating layer 34. Even in this case, the light can be prevented from reaching the sensor unit 41 of the white pixel 40 by being absorbed by the light shielding layer 37.
Even when the light beam 53 incident on the adjacent white pixel 40 leaks to the color pixel 30 side through the on-chip lens 46, it reaches the sensor unit 31 of the color pixel 30 by being absorbed by the light shielding layer 37. Can be prevented.

The thickness of the infrared cut filter 38 can be set to an arbitrary thickness depending on the amount of infrared light to be removed, the material constituting the infrared cut filter, and the like.
Further, the thickness of the light shielding layer 37 varies depending on the metal material used, but in order to reflect or absorb light incident on the light shielding layer 37, the thickness is preferably 20 nm or more and 50 nm or less. .
When the thickness of the light shielding layer 37 is less than 20 nm, the amount of light that passes through the light shielding layer 37 increases, and the effect of the light shielding layer 37 due to reflection or absorption is reduced. Moreover, since the light shielding layer 37 will become thick when the light shielding layer 37 exceeds 50 nm, it becomes difficult to miniaturize the whole device.

  As described above, since the light shielding layer 37 is formed on the side surface of the infrared cut filter 38, the side surface of the infrared cut filter 38 conventionally used for the solid-state imaging device is used as the light shielding layer 37. Therefore, it is not necessary to form a special structure as compared with the conventional case, and color mixture due to light leaking into adjacent pixels can be suppressed. Further, even when the thickness from the device sensor portion to the on-chip lens is increased, color mixture can be suppressed by reflecting or absorbing the light blocking layer 37. For this reason, the degree of freedom of design is improved in device design.

  In the present embodiment, the light shielding layer 37 is used on the side surface of the infrared cut filter 38, but the present invention is not limited to this. For example, it has a configuration capable of transmitting a specific wavelength, such as a band-pass filter, and is formed in a shape in which a light shielding layer 37 can be formed on the side surface of the sensor unit 31 via the insulating layer 34. If there is, it can be used similarly to the infrared cut filter 38.

  Next, the manufacturing method of the solid-state imaging device according to the second embodiment will be described with reference to FIGS. 5A to 5C and FIGS.

First, a wiring layer 39 is formed by sequentially forming a wiring and an insulating layer covering the wiring.
Thereafter, as shown in FIG. 5A, the insulating layers 34 and 44 are formed to a height at which the infrared cut filter 38 is provided by using SiO ₂ or the like using a CVD method or the like.

Next, as shown in FIG. 5B, on the insulating layers 34 and 44, a dielectric thin film that becomes the infrared cut filter 38, for example, Al ₂ O ₃ , TiO ₂ , SiO ₂ , SiN, etc. Dielectric thin films are alternately stacked to form a dielectric multilayer film 38A.
The uppermost layer of the dielectric multilayer film 38A is formed by laminating the same layers as the insulating layers 34 and 44. As a result, when the light shielding layer 37A is excessively etched when the light shielding layer 37A formed on the infrared cut filter 38 is etched in the subsequent steps, the insulating layer 34, the upper part of the dielectric multilayer film 38A, By etching 44, the upper portion of the infrared cut filter 38 can be prevented from being etched.

  Next, etching is performed using a known etching method so that the dielectric multilayer film 38A becomes the mesa-shaped infrared cut filter 38 shown in FIG. 5C.

  Next, the entire surface of the infrared cut filter 38 and the insulating layers 34 and 44 are coated with a metal having a high reflectance in the visible light region, or a metal or an inorganic material having an absorptance. As a result, as shown in FIG. 6D, a light shielding layer 37A is formed on the entire surface of the infrared cut filter 38 and the insulating layers 34 and 44.

  Further, before the light shielding layer 37A is formed on the infrared cut filter 38 and the insulating layers 34 and 44, a thin film such as Ti and Cr is formed on the insulating layers 34 and 44, and the thin film such as Ti and Cr is formed thereon. Alternatively, the light shielding layer 37A can be formed. Thereby, a protective film made of Ti, Cr or the like that protects the side surface of the infrared cut filter 38 and the interface with the light shielding layer 37 can be formed between the side surface of the infrared cut filter 38 and the light shielding layer 37. .

  Next, anisotropic etching is performed on the light shielding layer 37A. As a result, as shown in FIG. 6E, the light shielding layer 37A can be etched leaving the portion formed on the side wall of the mesa-shaped infrared cut filter 38, and the light shielding layer 37 is formed on the mesa-shaped side wall. be able to.

Next, on the insulating layers 34 and 44, the infrared cut filter 38, and the light shielding layer 37, the insulating layers 34 and 44 made of SiO ₂ or the like are formed again using the CVD method or the like.
Thereby, as shown in FIG. 6F, a shape in which the infrared cut filter 38 and the light shielding layer 37 are embedded in the insulating layer 34 can be formed.

  When the infrared cut filter 38 shown in FIG. 5C is etched, if the inclination angle of the mesa-shaped side wall is large, after the light shielding layer 37A is formed, the etching performed in the process shown in FIG. The light shielding layer 37 does not remain on the mesa-shaped side wall. For this reason, the inclination angle of the mesa-shaped side wall is preferably about 7 degrees.

  When the light shielding layer 37 is formed perpendicular to the sensor unit 31, the shape of the infrared cut filter 38 after etching shown in FIG. 5C is not a mesa shape, but the side wall of the infrared cut filter 38. Etching is performed so that is vertical. Thereby, the light shielding layer 37 can be formed perpendicular to the sensor unit 31.

Thereafter, in-layer lenses 33 and 43 are formed in the insulating layers 34 and 44 using a UV-SiN film or the like by a known method. Further, after forming one of the RGB color filters 35 and the white filter 45 on the insulating layers 34 and 44, the on-chip lenses 36 and 46 are sequentially formed.
With the above method, the solid-state imaging device of the second embodiment can be manufactured.

According to the above-described method, a known etching process and a thin film, such as a CVD method and dry etching, which are conventionally used in a semiconductor manufacturing process, as well as a process of forming an infrared cut filter 38 in a conventional pixel The light shielding layer 37 can be formed by using the laminating process.
For this reason, color mixing is suppressed by reflecting or absorbing light from adjacent pixels by the light shielding layer 37 by an easy manufacturing process without providing a special process as in the case of manufacturing a waveguide structure. A solid-state imaging device having a structure can be manufactured.

  Note that in the solid-state imaging device of the first embodiment, an infrared cut filter may be provided outside, and a light shielding layer may be provided in each pixel as a configuration that detects only visible light. For example, an infrared cut filter may be provided outside, the white pixel 20 may not be provided, and only the color pixel 10 may be configured, and the light shielding layer 17 may be provided in each color pixel 10.

  Further, in the solid-state imaging devices of the first embodiment and the second embodiment, intra-layer lenses 13, 23, 33, and 43 are provided in the pixels 10, 20, 30, and 40. However, even when a solid-state imaging device having a configuration in which the intra-layer lenses 13, 23, 33, and 43 are not provided in each pixel, the solid-state imaging device of the first embodiment and the second embodiment Similar effects can be obtained.

  Further, in the solid-state imaging device of the first embodiment and the second embodiment, the light shielding layers 17 and 37 are provided only for the color pixels 10 and 30, but the color pixels 10 are also provided for the white pixels 20 and 40. , 30 can be provided with the light shielding layers 17, 37. As a result, the light leaking into the adjacent pixels is reflected or absorbed by the light shielding layers 17 and 37, thereby suppressing the occurrence of color mixing.

  In the first embodiment and the second embodiment, a solid-state imaging device having a configuration in which a white filter that transmits both visible light and infrared light is provided has been described. However, the configuration of the device is not limited to this. For example, an element in which an infrared cut filter is provided outside and infrared light is not incident on a white pixel or a color array such as a general Bayer array can be used.

  In the above-described embodiment, the description is applied to a CMOS type solid-state imaging device. However, the present invention is not limited to this, and the present invention may be applied to other solid-state imaging devices (for example, a CCD).

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

1 is a schematic configuration diagram (cross-sectional view) of a solid-state imaging device according to a first embodiment of the present invention. FIGS. 8A to 8C are cross-sectional views for explaining the method for manufacturing the solid-state imaging element according to the first embodiment of the present invention. FIGS. D to E are cross-sectional views for explaining the method for manufacturing the solid-state imaging device according to the first embodiment of the present invention. It is a schematic block diagram (sectional drawing) of the solid-state image sensor of the 2nd Embodiment of this invention. FIGS. 8A to 8C are cross-sectional views for explaining a method for manufacturing a solid-state imaging device according to the second embodiment of the present invention. FIGS. DF is sectional drawing for demonstrating the manufacturing method of the solid-state image sensor of the 2nd Embodiment of this invention. It is a schematic block diagram (sectional drawing) of the conventional solid-state image sensor. It is a schematic block diagram (sectional drawing) of the conventional solid-state image sensor.

Explanation of symbols

  10, 30, 60, 80 Color pixel, 20, 40, 70, 90 White pixel, 11, 21, 31, 41, 61, 71, 81, 91 Sensor unit, 12, 22, 32, 42, 62, 72, 82, 92 Optical coupling layer, 13, 23, 33, 43, 63, 73, 83, 93 In-layer lens, 14, 24, 34, 44, 64, 74, 84, 94 Insulating layer, 15, 35, 65,85 Color filter, 25, 45, 75, 95 White filter, 16, 26, 36, 46, 66, 76, 86, 96 On-chip lens, 17, 17A, 37, 37A Light shielding layer, 38, 88 Infrared Cut filter, 19, 39, 69, 89 Wiring layer, 50, 51, 52, 53, 100, 101, 102, 103 Ray, 38A Dielectric multilayer

Claims (11)

It has a pixel composed of a sensor unit that performs photoelectric conversion, a color filter corresponding to the sensor unit, and a light shielding layer,
The light shielding layer is provided in the pixel between the sensor unit and the color filter, and is formed perpendicular to or substantially perpendicular to the sensor unit along the pixel separation unit. A solid-state imaging device.   The solid-state imaging device according to claim 1, wherein the light shielding layer is made of metal.   The solid-state imaging device according to claim 2, wherein the metal includes at least one selected from Ag, Rh, Pt, Mg, Al, Cu, and Au.   The solid-state imaging device according to claim 2, wherein the light shielding layer includes at least one selected from W, Ti, and Ta.   The solid-state imaging device according to claim 1, wherein the light shielding layer is formed of an inorganic material other than metal.   The solid-state imaging device according to claim 5, wherein the light shielding layer includes at least one selected from Si and Ge.   The solid-state imaging device according to claim 1, wherein an infrared cut filter is provided in the pixel.   The solid-state imaging device according to claim 7, wherein the light shielding layer is formed on a side wall of the infrared cut filter.   The solid-state imaging device according to claim 7, wherein the infrared cut filter has a mesa shape.   The solid-state imaging device according to claim 8, wherein a protective film is formed between a side wall of the infrared cut filter and the light shielding layer.   The solid-state imaging device according to claim 10, wherein the protective film includes at least one selected from Ti and Cr.

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