JP2005260067A - Solid-state imaging device and camera - Google Patents

Abstract

An object of the present invention is to increase the condensing rate of light incident on each unit pixel in a photoelectric conversion element and improve the sensitivity of each unit pixel.
In a pixel portion 1 of a solid-state imaging device, a plurality of photodiodes 41, 42, 43 are formed on a semiconductor substrate 10, and color filters 51, 52, 53 are disposed above the photodiodes 41, 42, 43. Are formed one by one. The light 15 and 16 incident on the first pixel C1 and the second pixel C2 has its green (G) wavelength region transmitted through the selective transmission layer 60, and its red (R) and blue (B). Are reflected by the selective transmission layer 60. The green (G) wavelength region transmitted through the selective transmission layer 60 passes through the second color filter 52 and enters the second photodiode 42. On the other hand, the red (R) and blue (B) wavelength regions reflected by the selective transmission layer 60 are transmitted through the first color filter 51 to the first photodiode 41. Incident.
[Selection] Figure 1

Description

  The present invention relates to a solid-state imaging device used for a digital camera, a mobile phone camera, and the like, and a camera equipped with the solid-state imaging device.

  FIG. 9 is a diagram illustrating a structure of a conventional solid-state imaging device. A large number of unit pixels 101 are two-dimensionally arranged in the pixel unit 100 of the solid-state imaging device. Each unit pixel 101 is connected to a vertical shift register 102 and a horizontal shift register 103. In addition, a driver circuit 105 that operates the vertical shift register 102, the horizontal shift register 103, and the output amplifier 104 is provided around the pixel portion 100. In the solid-state imaging device, each row of a large number of unit pixels 101 arranged two-dimensionally is selected by the vertical shift register 102, and the signal charge of the selected row is transferred to the horizontal shift register 103. The signal charge transferred to the horizontal shift register 103 is output from the output amplifier 104 for each unit pixel as a color signal.

  FIG. 10 is a cross-sectional view of the pixel unit 100 of the conventional solid-state imaging device. The pixel unit 100 is configured by laminating an interlayer insulating film 120 on a semiconductor substrate 110. A light shielding film 121 is formed inside the interlayer insulating film 120, and a color filter 140 is formed above the interlayer insulating film 120.

  The semiconductor substrate 110 includes a P-type layer 112 formed on an N-type layer 111, and a large number of N-type photodiodes 130 formed on the P-type layer 112 with an isolation region 113 therebetween. A light shielding film 121 that blocks incident light is formed above each separation region 113. One color filter 140 is formed above each photodiode 130. On the surface of the interlayer insulating film 120, one microlens 150 is formed above each color filter.

For example, the solid-state imaging device disclosed in Patent Document 1 has a structure in which a color filter and a microlens are simply formed above a photodiode that is a light receiving unit.
JP-A-6-61462

  In the pixel unit 100 of the solid-state imaging device, light incident toward each unit pixel 101 enters each microlens 150, passes through each color filter 140, and enters each photodiode 130 that is a photoelectric conversion element. .

  Here, it is assumed that the color filters 140 are arranged so that red (R) and green (G) appear alternately. The center color filter 140 shown in FIG. 10 is red (R), and the left and right color filters 140 are green (G). At this time, the light incident toward the central unit pixel 101 has its red (R) wavelength region transmitted through the central color filter 140 and incident on the photodiode 130 below it. On the other hand, the light incident on the left and right unit pixels 101 has its red (R) wavelength region absorbed by the left and right color filters 140. In other words, only the wavelength region having the same color as that of the color filter 140 is incident on the photodiode 130 and the remaining wavelength region is absorbed by the color filter 140. For this reason, the red (R) wavelength region on the unit pixel 101 around the center unit pixel 101 cannot be collected in the center photodiode 130.

  In addition to the red (R) wavelength region, when the central color filter 140 is blue (B), the blue (B) wavelength region on the unit pixel 101 around the central unit pixel 101 is changed. When the central color filter 140 is green (G) and cannot be collected in the central photodiode 130, the green (G) wavelength region on the unit pixel 101 around the central unit pixel 101 is centered. Cannot be collected in the photodiode 130. As described above, the conventional solid-state imaging device has a problem that the light collection rate in the photoelectric conversion element of the light incident on each unit pixel is poor, and the sensitivity of each unit pixel is poor.

  The present invention has been made in view of such a point, and an object of the present invention is to increase the condensing rate in the photoelectric conversion element of light incident on each unit pixel and improve the sensitivity of each unit pixel. There is.

  The first invention is directed to a solid-state imaging device having a photoelectric conversion element that performs photoelectric conversion of incident light and in which a plurality of unit pixels that are partitioned into a plurality of types of colors are two-dimensionally arranged. A selective transmission layer formed so as to cover a specific type of unit pixel, and the selective transmission layer has a higher transmittance with respect to a specific wavelength region than a transmittance with respect to other wavelength regions; The reflectance for the wavelength region is configured to be lower than the reflectance for the other wavelength regions.

  The light incident on a specific type of unit pixel has its specific wavelength region transmitted through the selective transmission layer and incident on the specific type of unit pixel, and other wavelength regions are reflected by the selective transmission layer. It enters the unit pixel of the type. In addition, light incident on other types of unit pixels is incident on other types of unit pixels. As a result, not only light incident on other types of unit pixels but also light incident on specific types of unit pixels can be incident on other unit pixels. Therefore, a photoelectric conversion element of another unit pixel can photoelectrically convert a much larger amount of light than before, and the sensitivity of other unit pixels can be greatly improved.

  In a second aspect based on the first aspect, the selective transmission layer is formed across the specific type of unit pixel and another type of unit pixel adjacent thereto.

  Light incident on other types of unit pixels is incident on other types of unit pixels. However, the light incident on the edge of another type of unit pixel has a specific wavelength because the selective transmission layer is formed across the specific type of unit pixel and the other type of unit pixel. The region is transmitted through the selective transmission layer and enters a specific type of unit pixel, and the other wavelength region is reflected by the selective transmission layer and is input to another type of unit pixel. As a result, not only light incident on a specific type of unit pixel but also light incident on an end of another type of unit pixel can be incident on the specific type of unit pixel. Therefore, a photoelectric conversion element of a specific unit pixel can photoelectrically convert a much larger amount of light than before, and not only the sensitivity of other unit pixels but also the sensitivity of a specific unit pixel can be greatly improved. Can do.

  In a third aspect based on the second aspect, the other type of unit pixel has a smaller area than the specific type of unit pixel.

  Here, since the selective transmission layer is formed to straddle a specific type of unit pixel and another type of unit pixel adjacent to the specific type of unit pixel, a region of light incident on the other type of unit pixel The area is smaller than the area area of light incident on a specific type of unit pixel. Therefore, if the area of the other type of unit pixel is made smaller than the area of the specific type of unit pixel, the sensitivity of the other type of unit pixel can be further greatly improved.

  According to a fourth invention, in the second invention, a micro lens is provided in the specific type of unit pixel and the other type of unit pixel, and the micro lens of the other type of unit pixel has the specific type of pixel. The planar size is smaller than the microlens of the unit pixel.

  Here, since the selective transmission layer is formed to straddle a specific type of unit pixel and another type of unit pixel adjacent to the specific type of unit pixel, a region of light incident on the other type of unit pixel The area is smaller than the area area of light incident on a specific type of unit pixel. Therefore, if the planar size of the micro lens of another type of unit pixel is made smaller than the planar size of the micro lens of a specific type of unit pixel, the light collection rate of the micro lens of each unit pixel can be increased. Thus, the sensitivity of each unit pixel can be further greatly improved.

  According to a fifth invention, in the second invention, a color filter is provided in the specific type of unit pixel and the other type of unit pixel, and the color filter of the specific type of unit pixel is the other type of unit pixel. The area of the surface on which the incident light is incident is larger than the color filter of the unit pixel.

  Here, since the selective transmission layer is formed to straddle a specific type of unit pixel and another type of unit pixel adjacent to the specific type of unit pixel, a region of light incident on the other type of unit pixel The area is smaller than the area area of light incident on a specific type of unit pixel. Therefore, if the area of the color filter of a specific type of unit pixel is made larger than the area of the color filter of another type of unit pixel, the amount of light transmitted through the color filter of the specific type of unit pixel can be increased. The sensitivity of a specific type of unit pixel can be further greatly improved.

  According to a sixth invention, in the second invention, the photoelectric conversion element of the other type of unit pixel has a smaller surface area on which incident light is incident than the specific type of unit pixel. .

  Here, since the selective transmission layer is formed to straddle a specific type of unit pixel and another type of unit pixel adjacent to the specific type of unit pixel, a region of light incident on the other type of unit pixel The area is smaller than the area area of light incident on a specific type of unit pixel. Therefore, if the area of the photoelectric conversion element of the other type of unit pixel is made smaller than the area of the photoelectric conversion element of the specific type of unit pixel, the light collection rate in the photoelectric conversion element of each unit pixel can be increased. The sensitivity of the unit pixel can be further greatly improved.

  A seventh invention is a camera equipped with the solid-state imaging device according to any one of the first to sixth inventions. Thereby, a camera equipped with the solid-state imaging device according to any one of the first to sixth aspects can be provided.

  According to the solid-state imaging device of the present invention, a photoelectric conversion element of a specific unit pixel and other unit pixels can photoelectrically convert a much larger amount of light than before, greatly increasing the sensitivity of each unit pixel. Can be improved. In addition, according to the present invention, a camera equipped with this solid-state imaging device can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a cross-sectional view of the pixel unit 1 of the solid-state imaging device according to the first embodiment. The pixel unit 1 of the solid-state imaging device is configured by laminating an interlayer insulating film 20 on a semiconductor substrate 10. A light shielding film (not shown) is formed inside the interlayer insulating film 20, and color filters 51, 52, 53 are formed on the interlayer insulating film 20.

  The semiconductor substrate 10 has a P-type layer 12 formed on an N-type layer 11 and a large number of N-type photodiodes 41, 42, 43 formed on the P-type layer 12 with an isolation region 13 therebetween. Has been. In FIG. 1, a first photodiode 41 is formed on the left side of the P-type layer 12, a second photodiode 42 is formed in the center thereof, and a third photodiode 43 is formed on the right side thereof. Each photodiode 41, 42, 43 constitutes a photoelectric conversion element that performs photoelectric conversion of incident light.

  One color filter 51, 52, 53 is formed above each of the photodiodes 41, 42, 43. These color filters 51, 52, 53 are arranged so that red (R) and green (G) appear alternately. Specifically, a first color filter 51 having a red color (R) above the first photodiode 41 and a second color filter 52 having a green color (G) above the second photodiode 42 are provided. A third color filter 53 having red (R) is formed above the third photodiode 43, respectively.

  In the pixel unit 1, the first photodiode 41 and the first color filter 51 constitute the first pixel C1, and the second photodiode 42 and the second color filter 52 are the second. The third photodiode 43 and the third color filter 53 constitute the third pixel C3. The first pixel C1, the second pixel C2, and the third pixel C3 are adjacent to each other. In the present embodiment, among the plurality of unit pixels divided into a plurality of types of colors, the first pixel C1 and the third pixel C3 are partitioned in red (R), and the second pixel C2 is green. It is divided into (G).

A large number of convex SiO ₂ films 30 having a substantially conical shape are formed on the surface of the interlayer insulating film 20. In FIG. 1, each SiO ₂ film 30 is formed so as to cover three unit pixels. The center SiO ₂ film 30 is formed so that the bottom thereof covers the right end of the first pixel C1 and the left end of the third pixel C3. Further, the left SiO ₂ film 30 is formed such that its bottom portion covers the left end portion of the first pixel C1, and the right SiO ₂ film 30 has its bottom portion covering the right end portion of the third pixel C3. Is formed.

A selective transmission layer 60 is formed on the side surface of each SiO ₂ film 30. Specifically, the selective transmission layer 60 is formed on the side surface of the central SiO ₂ film 30 across the right end portion of the first pixel C1 and the second pixel C2, and the second pixel C2 and the third pixel C2 are formed. Is formed across the left end of the pixel C3. Further, the side surface of the left side of the SiO ₂ film 30 is selectively permeable layer 60 is formed to span the left end portion of the first pixel C1, selectively permeable layer 60 on the side of the right SiO ₂ film 30 is first It is formed so as to cover the right end of the third pixel C3. The selective transmission layer 60 is composed of a dielectric laminated film 61 formed by laminating dielectric materials such as TiO ₂ and SiO ₂ having high transparency to visible light and different refractive indexes. .

  The selective transmission layer 60 has a higher transmittance with respect to a specific wavelength region of light incident on the unit pixel than that with respect to other wavelength regions, and a specific portion of light incident on the unit pixel. The reflectance for the wavelength region is configured to be lower than the reflectance for the other wavelength regions. Specifically, the selective transmission layer 60 has a red transmittance with respect to the green (G) wavelength region of light incident on each of the first, second, and third pixels C1, C2, and C3. Of the light incident on the first, second, and third pixels C1, C2, and C3, which is higher than the transmittance for the wavelength region of (R) and blue (B), green (G) The reflectance for the wavelength region is configured to be lower than the reflectance for the red (R) and blue (B) wavelength regions.

-Path of light incident on the pixel part-
The path of light incident on the pixel unit 1 of the solid-state imaging device will be described with reference to FIG.

  Lights 15, 16, and 17 incident on the first, second, and third pixels C1, C2, and C3 are respectively green (G), red (R), and blue (B ) Wavelength region.

  The light 16 incident on the second pixel C2 has its green (G) wavelength region transmitted through the selective transmission layer 60, and its red (R) and blue (B) wavelength regions have a selective transmission layer. Reflected at 60. Of the light 16 incident on the second pixel C2, the green (G) wavelength region transmitted through the selective transmission layer 60 passes through the second color filter 52 and enters the second photodiode 42. . Of the light 16 incident on the second pixel C2, the red (R) and blue (B) wavelength regions reflected by the selective transmission layer 60 have the red (R) wavelength region as the first color filter. 51, enters the first photodiode 41, and the blue (B) wavelength region is absorbed by the first color filter 51.

  On the other hand, the light 15 incident on the first pixel C1 has its red (R) wavelength region transmitted through the first color filter 51 and incident on the first photodiode 41, and its green (G). The blue (B) wavelength region is absorbed by the first color filter 51. Further, the light 17 incident on the third pixel C3 has its red (R) wavelength region transmitted through the third color filter 53 and incident on the third photodiode 43, and its green (G). The blue (B) wavelength region is absorbed by the first color filter 53.

  However, the light 15 incident on the right end portion of the first pixel C1 has a green color (G) because the selective transmission layer 60 is formed across the first pixel C1 and the second pixel C2. ) Is refracted in the direction of the second pixel C2 on the surface of the selective transmission layer 60, transmits through the selective transmission layer 60, and transmits through the second color filter 52 to the second photodiode 42. Incident. Of the light 15 incident on the right end of the first pixel C1, the red (R) and blue (B) wavelength regions are reflected by the selective transmission layer 60, and the red (R) wavelength region is the first wavelength region. The first color filter 51 passes through the first photodiode 41 and enters the first photodiode 41, and the blue (B) wavelength region is absorbed by the first color filter 51.

  Further, the light 17 incident toward the left end of the third pixel C3 has a green color (G) because the selective transmission layer 60 is formed across the second pixel C2 and the third pixel C3. ) Is refracted in the direction of the second pixel C2 on the surface of the selective transmission layer 60, transmits through the selective transmission layer 60, and transmits through the second color filter 52 to the second photodiode 42. Incident. Of the light 17 incident toward the left end of the third pixel C3, the red (R) and blue (B) wavelength regions are reflected by the selective transmission layer 60, and the red (R) wavelength region is the first wavelength region. The third color filter 53 passes through the third photodiode 43 and enters the third photodiode 43, and the blue (B) wavelength region is absorbed by the third color filter 53.

-Pixel part formation process-
A process for forming the pixel portion 1 of the solid-state imaging device will be described with reference to FIGS.

FIG. 2 is a diagram illustrating a formation process of the pixel portion 1 of the solid-state imaging device. First, as shown in FIG. 2A, a P-type layer 12, a plurality of photodiodes 41, 42, 43, a separation region 13, and a plurality of color filters 51, 52, 53 are formed on the N-type layer 11. A highly transparent insulating film such as a SiO ₂ film (silicon oxide film) 30 is deposited on the surface of the wafer using the CVD method. Subsequently, as shown in FIG. 2B, a resist pattern 31 is formed on the surface of the SiO ₂ film 30 by a normal photolithography process.

Thereafter, the SiO ₂ film 30 is physically etched using a CF ₄ etching gas to form the SiO ₂ film 30 in a convex shape. At this time, lateral etching (side etching) is performed simultaneously with etching in the thickness direction, and the SiO ₂ film 30 is finally formed in a convex shape (see FIG. 2C). Further, as shown in FIG. 2 (d), in order to prevent the dielectric laminated film 61 from being deposited on the first pixel C1 or the third pixel C3, between the adjacent SiO ₂ films 30. Then, a resist pattern 32 is formed by a photolithography process.

Next, as shown in FIG. 2 (e), (here, the left side surface of the SiO ₂ film 30) one side surface of the SiO ₂ film 30 formed on the convex, TiO ₂ and SiO using a sputtering apparatus _A dielectric laminated film 61 made of 2 is formed. Similarly, as shown in FIG. 2 (f), (here, the right side surface of the SiO ₂ film 30) the other side of the SiO ₂ film 30 formed in a convex shape, the dielectric multilayer film by using the sputtering apparatus 61 is formed. In this way, the dielectric laminated film 61 is formed on the side surface of the convexly formed SiO ₂ film 30. In the actual film formation, in order to form the dielectric laminated film 61 with good controllability and stability on the side surface of the convex SiO ₂ film 30, in the incident direction of a deposition gas such as TiO ₂ or SiO _2. On the other hand, the dielectric laminated film 61 is formed by tilting the wafer by the tilt of the SiO ₂ film 30.

  Finally, as shown in FIG. 2G, the resist formed on the first pixel C1 and the third pixel C3 is removed by a lift-off process, and the dielectric laminated film 61 deposited on the surface of the resist is removed. Is selectively removed.

The film thickness of the SiO ₂ film 30 is determined by the incident angle of light incident on the selective transmission layer 60 formed of the dielectric laminated film 61. Specifically, the film thickness of the SiO ₂ film 30 is such that, for example, when light incident on each unit pixel is incident on the wafer perpendicularly and incident on the dielectric laminated film 61 at 60 °, for example, the pixel If the period is 3 μm, it is about 2.6 μm.

Further, the bottom portion of the SiO ₂ film 30 formed in a convex shape is formed so as to cover the adjacent left and right unit pixels with one unit pixel interposed therebetween. In the present embodiment, as shown in FIG. 1, the bottom of the central SiO ₂ film 30 is formed so as to cover the first pixel C1 and the third pixel C3, and the bottom of the dielectric laminated film 61 is the second. It is important to form the first pixel C1 and the third pixel C3, not the first pixel C2. If the bottom of the dielectric laminated film 61 is on the second pixel C2, it is reflected by the selective transmission layer 60 out of the light 15 and 16 incident on the first pixel C1 and the second pixel C2. The red (R) wavelength region is incident not only on the first color filter 51 having red (R) but also on the second color filter 52 having green (G), and the sensitivity of each unit pixel. This is because there is a risk of lowering.

  3A is a cross-sectional view of the dielectric multilayer film 61, and FIG. 3B is a simulation result of the transmittance characteristics of the selective transmission layer 60 constituted by the dielectric multilayer film 61. FIG.

As shown in FIG. 3A, the dielectric laminated film 61 is formed on the surface of the SiO ₂ film 30 and is configured by alternately laminating TiO ₂ films 62 and SiO ₂ films 63. In the simulation, it is assumed that a characteristic matrix method widely known in multilayer filters is employed, and incident light is incident on the dielectric laminated film 61 at 60 °. The refractive index values of TiO ₂ and SiO ₂ are 2.5 and 1.45, respectively, and the film thicknesses of the TiO ₂ film 62 and the SiO ₂ film 63 are both 265 nm in terms of optical film thickness values. However, only the central TiO ₂ film 62 has a thickness twice that of the other films.

  In FIG. 3B, the horizontal axis represents the wavelength of incident light, and the vertical axis represents the transmittance of light incident on the selective transmission layer 60. As shown in the figure, a transmittance of 90% or more is obtained in the vicinity of 550 nm which is the green (G) wavelength region of the incident light. That is, 90% or more of the green (G) wavelength region of the light incident on the selective transmission layer 60 passes through the selective transmission layer 60 and enters the second pixel C2. On the other hand, in the vicinity of 450 nm, which is the blue (B) wavelength region of the incident light, and 650 nm, which is the red (R) wavelength region, the transmittance decreases to about 20% and the reflectance increases to about 80%. . That is, about 80% of the blue (B) and red (R) wavelength regions out of the light incident on the selective transmission layer 60 are reflected by the selective transmission layer 60, and the first pixel C1 and the third wavelength region of the third pixel. The light enters the pixel C3.

  From the above simulation results, it is possible to improve the sensitivity of the first photodiode 41 to about 1.8 times the conventional sensitivity. Similarly, the sensitivity of the third photodiode 43 can be improved to about 1.8 times the conventional sensitivity.

-Effects of the first embodiment-
In this embodiment, the light 16 incident on the second pixel C2 has its green (G) wavelength region transmitted through the selective transmission layer 60 and is incident on the second pixel C2, and is red (R). The blue (B) wavelength region is reflected by the selective transmission layer 60 and is incident on the first pixel C1. Further, the light 15 incident on the first pixel C1 enters the first pixel C1. As a result, not only the light 15 incident on the first pixel C1 but also the light 16 incident on the second pixel C2 can be incident on the first pixel C1. Therefore, according to the present embodiment, the first photodiode 41 can photoelectrically convert a much larger amount of light than the conventional one, and the sensitivity of the first pixel C1 can be greatly improved. Similarly, the third photodiode 43 can photoelectrically convert a much larger amount of light than the conventional one, and the sensitivity of the third pixel C3 can be greatly improved.

  In the present embodiment, the light 15 incident toward the end of the first pixel C1 has a green (G) green color because the selective transmission layer 60 is formed across the first pixel C1. The wavelength region is transmitted through the selective transmission layer 60 and incident on the second pixel C2, and the red (R) and blue (B) wavelength regions are reflected by the selective transmission layer 60 to the first pixel C1. Incident. Similarly, the light 17 incident on the end of the third pixel C3 is selected in the green (G) wavelength region because the selective transmission layer 60 is formed across the third pixel C3. The red (R) and blue (B) wavelength regions are reflected by the selective transmission layer 60 and incident on the third pixel C3. Thereby, not only the light 16 incident on the second pixel C2, but also the light 15 incident on the end of the first pixel C1 and the light 17 incident on the end of the third pixel C3. Can also be incident on the second pixel C2.

  Therefore, according to the present embodiment, the second photodiode 42 can photoelectrically convert a much larger amount of light than the conventional one, and not only the sensitivity of the first pixel C1 and the third pixel C3. The sensitivity of the second pixel C2 can be greatly improved.

(Second Embodiment)
FIG. 4 is a cross-sectional view of the pixel unit 1 of the solid-state imaging device according to the second embodiment. Since the structure of the pixel unit 1 of the solid-state imaging device of the present embodiment is basically the same as that of the first embodiment, only differences from the first embodiment will be described.

  In the pixel portion 1 of the solid-state imaging device of the present embodiment, one microlens 71, 72, 73 is formed on the surface of the interlayer insulating film 20 above the color filters 51, 52, 53.

As shown in FIG. 4, on the upper surface of the interlayer insulating film 20, the first microlens 71 is above the first color filter 51, and the second microlens 72 is above the second color filter 52. Third microlenses 73 are formed above the third color filter 53, respectively. The first microlens 71 and the third microlens 73 are formed between adjacent SiO ₂ films 30 and have an outer diameter smaller than that of the second microlens 72. The first micro lens 71 is provided in the first pixel C1, the second micro lens 72 is provided in the second pixel C2, and the third micro lens 73 is provided in the third pixel C3.

  Of the light 15 incident on the first pixel C1, the green (G) wavelength region that has been transmitted through the selective transmission layer 60 is incident on the second microlens 72 and is transmitted through the second color filter 52. To the second photodiode 42. On the other hand, the red (R) and blue (B) wavelength regions reflected by the selective transmission layer 60 out of the light 15 incident on the first pixel C 1 enter the first microlens 71. The light incident on the first microlens 71 has its red (R) wavelength region transmitted through the first color filter 51 and incident on the first photodiode 41, and its blue (B) wavelength region. Absorbed by the first color filter 51. Note that the path of the light 16 incident on the second pixel C2 is the same as the path of the light 15 incident on the first pixel C1.

  Here, since the selective transmission layer 60 is formed across the first pixel C1 and the second pixel C2 adjacent to the first pixel C1, the area area of the light incident on the first pixel C1 Is smaller than the area of the light incident on the second pixel C2. Similarly, since the selective transmission layer 60 is formed across the second pixel C2 and the third pixel C3 adjacent to the second pixel C2, the area area of the light incident on the third pixel C3 Is smaller than the area of the light incident on the second pixel C2. Therefore, if the planar size of the first microlens 71 and the third microlens 73 is made smaller than the planar size of the second microlens 72, the light condensing in each microlens 71, 72, 73. The rate can be increased, and the sensitivity of each unit pixel can be further greatly improved.

(Third embodiment)
FIG. 5 is a cross-sectional view of the pixel unit 1 of the solid-state imaging device according to the third embodiment. Since the structure of the pixel unit 1 of the solid-state imaging device of the present embodiment is basically the same as that of the first embodiment, only differences from the first embodiment will be described.

  In the pixel unit 1 of the solid-state imaging device of the present embodiment, the areas of the surfaces on which the incident light of the photodiodes 41, 42, and 43 are incident are different.

  As shown in FIG. 5, the first photodiode 41 and the third photodiode 43 are smaller in area of the surface on which incident light is incident than the second photodiode 42. In the present embodiment, the first photodiode 41 and the third photodiode 43 have a surface area on which incident light is incident that is smaller than that of the first embodiment. The area of the surface on which the incident light enters the diode 42 is larger than that of the first embodiment.

  Here, since the selective transmission layer 60 is formed across the first pixel C1 and the second pixel C2 adjacent to the first pixel C1, the area area of the light incident on the first pixel C1 Is smaller than the area of the light incident on the second pixel C2. Similarly, since the selective transmission layer 60 is formed across the second pixel C2 and the third pixel C3 adjacent to the second pixel C2, the area area of the light incident on the third pixel C3 Is smaller than the area of the light incident on the second pixel C2. Therefore, if the area of the first photodiode 41 and the third photodiode 43 is made smaller than the area of the second photodiode 42, the light collection rate in each of the photodiodes 41, 42, 43 can be increased. The sensitivity of each unit pixel can be further greatly improved.

(Fourth embodiment)
FIG. 6 is a cross-sectional view of the pixel unit 1 of the solid-state imaging device according to the fourth embodiment. Since the structure of the pixel unit 1 of the solid-state imaging device of the present embodiment is basically the same as that of the first embodiment, only differences from the first embodiment will be described.

  In the pixel unit 1 of the solid-state imaging device of the present embodiment, the areas of the surfaces on which incident light of the color filters 51, 52, and 53 are incident are different. As shown in FIG. 6, the area of the surface on which the incident light enters the second color filter 52 is larger than those of the first color filter 51 and the third color filter 53.

  Here, since the selective transmission layer 60 is formed across the first pixel C1 and the second pixel C2 adjacent to the first pixel C1, the area area of the light incident on the first pixel C1 Is smaller than the area of the light incident on the second pixel C2. Similarly, since the selective transmission layer 60 is formed across the second pixel C2 and the third pixel C3 adjacent to the second pixel C2, the area area of the light incident on the third pixel C3 Is smaller than the area of the light incident on the second pixel C2. Therefore, if the area of the second color filter 52 is made larger than the areas of the first color filter 51 and the third color filter 53, the amount of light in the green (G) wavelength region incident on the second color filter 52 Can be increased, and the sensitivity of the second pixel C2 can be further improved.

(Other embodiments)
In the solid-state imaging devices of the first to fourth embodiments, the transmittance for the green (G) wavelength region of the light incident on the selective transmission layer 60 toward the unit pixel is red (R) and blue (B ) Higher than the transmittance for the wavelength region, and the reflectance for the green (G) wavelength region of the light incident toward the unit pixel is higher than the reflectance for the red (R) and blue (B) wavelength regions. It has a configuration that lowers.

  Not limited to this, by changing the configuration of the dielectric laminated film 61, the transmittance with respect to the blue (B) wavelength region of the light incident on the selective transmission layer 60 toward the unit pixel is green (G) and red. The reflectance with respect to the wavelength region of green (G) and red (R) is higher than the transmittance with respect to the wavelength region of (R) and the reflectance with respect to the wavelength region of blue (B) among the light incident toward the unit pixel. Or the transmittance with respect to the red (R) wavelength region of the light that enters the selective transmission layer 60 toward the unit pixel with respect to the green (G) and blue (B) wavelength regions. Of the light that is higher than the transmittance and that enters the unit pixel, the reflectance for the red (R) wavelength region is lower than the reflectance for the green (G) and blue (B) wavelength regions. Can also A.

Of the light that enters the selective transmission layer 60 toward the unit pixel, the transmittance for the blue (B) wavelength region is higher than the transmittance for the green (G) and red (R) wavelength regions, and the unit pixel In the case where the reflectance for the blue (B) wavelength region of the incident light is lower than the reflectances for the green (G) and red (R) wavelength regions, FIG. As shown, the center TiO ₂ film 62 of the dielectric laminated film 61 is divided into two layers in the lamination direction, and an SiO ₂ film 63 having a larger film thickness than the other films is formed therebetween.

  With such a configuration, as shown in FIG. 7B, a transmittance close to 100% can be obtained in the vicinity of 450 nm, which is the blue (B) wavelength region of the incident light. That is, almost 100% of the blue (B) wavelength region of the light incident on the selective transmission layer 60 is transmitted through the selective transmission layer 60. On the other hand, in the vicinity of 550 nm which is the green (G) wavelength region and the red (R) wavelength region of the incident light, the transmittance is reduced to about 10% and the reflectance is increased to about 90%. . That is, about 90% of the wavelength region of green (G) or red (R) in the light incident on the selective transmission layer 60 is reflected by the selective transmission layer 60.

In addition, the transmittance of the light incident on the unit pixel toward the unit pixel in the red (R) wavelength region is higher than the transmittance in the green (G) and blue (B) wavelength regions, and the unit When the reflectance for the red (R) wavelength region of the light incident on the pixel is lower than the reflectance for the green (G) and blue (B) wavelength regions, FIG. ), The middle TiO ₂ film 62 of the dielectric laminated film 61 is divided into two layers in the lamination direction, and an SiO ₂ film 63 having a smaller film thickness than the other films is formed therebetween.

  With such a configuration, as shown in FIG. 8B, a transmittance close to 100% is obtained in the vicinity of 650 nm to which the red (R) wavelength region belongs in the incident light. That is, almost 100% of the red (R) wavelength region of the light incident on the selective transmission layer 60 is transmitted through the selective transmission layer 60. On the other hand, in the vicinity of 450 nm which is the blue (B) wavelength region and 550 nm which is the green (G) wavelength region of the incident light, the transmittance decreases to about 10% and the reflectance increases to about 90%. . That is, about 90% of the wavelength range of green (G) and blue (B) out of the light incident on the selective transmission layer 60 is reflected by the selective transmission layer 60.

  Thus, even when the configuration of the dielectric laminated film 61 is changed, the transmittance close to 100% with respect to a specific wavelength region in the light incident on the selective transmission layer 60 and 90 with respect to other wavelength regions. % Reflectance can be realized, and the sensitivity of each unit pixel can be greatly improved.

  As described above, the present invention is useful for a solid-state imaging device used for a digital camera, a camera for a mobile phone, and a camera equipped with the solid-state imaging device.

It is sectional drawing of the pixel part of the solid-state imaging device which concerns on 1st Embodiment. It is a figure which shows the formation process of the pixel part of the solid-state imaging device which concerns on 1st Embodiment. (A) is sectional drawing of the dielectric multilayer film which concerns on 1st Embodiment, (b) is a figure which shows the simulation result of the transmittance | permeability characteristic of the selective transmission layer which concerns on 1st Embodiment. It is sectional drawing of the pixel part of the solid-state imaging device which concerns on 2nd Embodiment. It is sectional drawing of the pixel part of the solid-state imaging device which concerns on 3rd Embodiment. It is sectional drawing of the pixel part of the solid-state imaging device which concerns on 4th Embodiment. (A) is sectional drawing of the dielectric multilayer film which concerns on other embodiment, (b) is a figure which shows the simulation result of the transmittance | permeability characteristic of the selective transmission layer which concerns on other embodiment. (A) is sectional drawing of the dielectric multilayer film which concerns on other embodiment, (b) is a figure which shows the simulation result of the transmittance | permeability characteristic of the selective transmission layer which concerns on other embodiment. It is a figure which shows the structure of the conventional solid-state imaging device. It is sectional drawing of the pixel part of the conventional solid-state imaging device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Semiconductor substrate 11 N-type layer 12 P-type layer 13 Separation region 15 Light incident on the first pixel 16 Light incident on the second pixel 17 Light incident on the third pixel 20 Interlayer insulation Film 30 SiO ₂ film 31 resist pattern 32 resist pattern 41 first photodiode 42 second photodiode 43 third photodiode 51 first color filter 52 second color filter 53 third color filter 60 selective Transmission layer 61 Dielectric laminated film 62 TiO ₂ film 63 SiO ₂ film 71 First microlens 72 Second microlens 73 Third microlens C1 First pixel C2 Second pixel C3 Third pixel

Claims (7)

In a solid-state imaging device having a photoelectric conversion element that performs photoelectric conversion of incident light, and a plurality of unit pixels that are partitioned into a plurality of types of colors are two-dimensionally arranged,
A selective transmission layer formed so as to cover a specific type of unit pixel;
The selective transmission layer is configured such that the transmittance with respect to a specific wavelength region is higher than the transmittance with respect to another wavelength region, and the reflectance with respect to the specific wavelength region is lower than the reflectance with respect to the other wavelength region. A solid-state imaging device. The solid-state imaging device according to claim 1,
The selective transmission layer is a solid-state imaging device formed across the specific type of unit pixel and another type of adjacent unit pixel. The solid-state imaging device according to claim 2,
The other type of unit pixel is a solid-state imaging device having an area smaller than that of the specific type of unit pixel. The solid-state imaging device according to claim 2,
The specific type unit pixel and the other type of unit pixel are provided with microlenses,
The micro lens of the other type of unit pixel is a solid-state imaging device whose planar size is smaller than the micro lens of the specific type of unit pixel. The solid-state imaging device according to claim 2,
The specific type of unit pixel and the other type of unit pixel are provided with color filters,
The color filter of the specific type of unit pixel is a solid-state imaging device in which the area of the surface on which incident light is incident is larger than the color filter of the other type of unit pixel. The solid-state imaging device according to claim 2,
The photoelectric conversion element of the other type of unit pixel is a solid-state imaging device in which an area of a surface on which incident light is incident is smaller than that of the specific type of unit pixel. A camera equipped with the solid-state imaging device according to claim 1.

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