JP4681853B2 - Stacked solid-state imaging device - Google Patents

Description

  The present invention relates to a stacked solid-state imaging device that captures a color image.

  Conventionally, single-type color solid-state imaging devices such as CCD and CMOS image sensors mounted on digital cameras and digital video cameras have the same photoelectric conversion elements of millions of pixels and signal readout circuits for reading signals from each pixel. It was the structure formed on a semiconductor substrate. In this case, the area of the light receiving surface of each photoelectric conversion element cannot be widened, the size of the light receiving surface is in the wavelength order of incident light, the amount of light that can be detected by one pixel is reduced, and the sensitivity is reduced. There was a disadvantage that the yield decreased and the cost increased.

  Therefore, conventionally, only a signal readout circuit is provided on a semiconductor substrate, and a red detection photoelectric conversion film, a green detection photoelectric conversion film, and a blue detection photoelectric conversion film are laminated on the upper layer portion of the semiconductor substrate. A stacked solid-state image pickup device having the above has been developed.

However, laminating three layers of photoelectric conversion films on a semiconductor substrate has a drawback that the structure becomes complicated and difficult to manufacture, and the manufacturing cost increases. For this reason, in the following Patent Document 1, a photoelectric conversion element for red detection and a photoelectric conversion element for blue detection are manufactured on a semiconductor substrate in the same manner as a conventional CCD or CMOS image sensor, and green detection is performed on the upper part of the semiconductor substrate. Has proposed a stacked solid-state imaging device having a structure in which only one photoelectric conversion film is stacked.
Patent Documents 2 and 3 below describe a configuration in which, in a stacked image sensor, amorphous silicon is stacked on a CCD or CMOS image sensor to improve the aperture ratio of the light receiving unit.

JP 2003-332551 A JP-A-1-295458 Japanese Patent Laid-Open No. 5-167056

  When a single photoelectric conversion film is stacked on a semiconductor substrate to detect one of the three primary colors, and the other two colors are detected by photodiodes (photoelectric conversion elements) provided on the semiconductor substrate, Since the area of one pixel of the photoelectric conversion film can be increased, the amount of light received in the wavelength region received by the photoelectric conversion film can be increased, and the sensitivity is improved.

  However, since light incident on the photodiode provided on the semiconductor substrate is absorbed when passing through the transparent pixel electrode film connected to the photoelectric conversion film, there is room for further improvement in light utilization efficiency. there were.

  Patent Document 1 does not describe the relationship between the arrangement of the pixel electrode film connected to the photoelectric conversion film and the arrangement of the photodiode provided on the semiconductor substrate. The problem of absorption by the transparent electrode film connected to the conversion film could not be solved.

  In Patent Documents 2 and 3, since the pixel electrode film is formed so as to cover the photoelectric conversion element such as a storage diode provided on the semiconductor substrate, it is caused by absorption by the pixel electrode film. Thus, it is inevitable that the utilization efficiency of light received by the photoelectric conversion element is reduced.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a stacked solid-state imaging device capable of increasing light received by a photoelectric conversion unit provided on a semiconductor substrate.

The object of the present invention is to provide a semiconductor substrate in which a blue photoelectric conversion unit for detecting light of a blue wavelength and a red photoelectric conversion unit for detecting light of a red wavelength are arranged two-dimensionally, and on the semiconductor substrate. And a photoelectric conversion film that detects light having a green wavelength, and the photoelectric conversion film is disposed so as to cover the blue photoelectric conversion unit and the red photoelectric conversion unit. The photoelectric conversion film is connected to pixel electrode films arranged at regular intervals for each pixel, and when the blue photoelectric conversion unit and the red photoelectric conversion unit are viewed from a direction perpendicular to the semiconductor substrate. In addition, the present invention is achieved by a stacked solid-state imaging device, which is disposed between the pixel electrode films.

  In the stacked solid-state imaging device, the photoelectric conversion film is a transmissive organic semiconductor.

In the stacked solid-state imaging device, a charge accumulation unit is connected to the photoelectric conversion film, and the area of the charge accumulation unit is smaller than each area of the blue photoelectric conversion unit and the red photoelectric conversion unit in the incident direction of light. Features.

In the stacked solid-state imaging device, a color filter that transmits incident light is provided above the blue photoelectric conversion unit and the red photoelectric conversion unit and below the photoelectric conversion film , respectively. Microlenses are provided on the side surfaces, respectively.

  ADVANTAGE OF THE INVENTION According to this invention, the lamination type solid-state imaging device which can increase the light received by the photoelectric conversion part provided in the semiconductor substrate can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a plan view showing a first embodiment of a stacked solid-state imaging device according to the present invention. As shown in FIG. 1, the stacked solid-state imaging device 10 includes a semiconductor substrate 1, and a plurality of blue photoelectric conversion units 3 and a plurality of red photoelectric conversion units 4 are arranged on the surface of the semiconductor substrate 1. Yes. The blue photoelectric conversion unit 3 is configured to receive blue wavelength and accumulate blue signal charge, and the red photoelectric conversion unit 4 is configured to receive red wavelength light and accumulate red signal charge. is there. In the present embodiment, photodiodes are used as the blue photoelectric conversion unit 3 and the red photoelectric conversion unit 4. In the present embodiment, the blue photoelectric conversion unit 3 and the red photoelectric conversion unit 4 have a rhombic plane that is perpendicular to the incident direction of light (the direction when FIG. 1 is viewed from the front).

  The semiconductor substrate 1 receives a green wavelength and generates a charge corresponding to the amount of received light. The pixel electrode film 12 is electrically connected to the pixel electrode film 12 and receives a green signal from the pixel electrode film 12. A signal storage unit 2 for storing electric charge is provided. In the present embodiment, the pixel electrode film 12 and the signal storage unit 2 have a rhombic plane perpendicular to the light incident direction, and the area of the plane in the signal storage unit 2 is equal to that of the blue photoelectric conversion unit 3 and It is smaller than the red photoelectric conversion unit 4 and is in a range of 20% to 30% of each area of the blue photoelectric conversion unit 3 and the red photoelectric conversion unit 4.

  In FIG. 1, R means red, G means green, B means blue, and the arrangement of the green signal storage unit 2, blue photoelectric conversion unit 3, and red photoelectric conversion unit 4 is as follows. Show.

  The signal storage unit 2, the blue photoelectric conversion unit 3, and the red photoelectric conversion unit 4 have a square lattice shape so that the blue photoelectric conversion unit 3 and the red photoelectric conversion unit 4 are alternately positioned via the signal storage unit 2. Is arranged. Specifically, as shown in FIG. 1, G, R, G, B, G... Are repeatedly arranged in the horizontal direction and the vertical direction.

  On the upper surface of the semiconductor substrate 1 in a plan view, between the signal storage unit 2 and the blue photoelectric conversion unit 3 and between the signal storage unit 2 and the red photoelectric conversion unit 4, respectively, as shown in FIG. The vertical transfer path 6 is provided so as to extend in the vertical direction in plan view. The vertical transfer path 6 is formed in a meandering state so as to be close to each other in accordance with the area of the signal storage unit 2 and the size of each area of the blue photoelectric conversion unit 3 and the red photoelectric conversion unit 4.

  A horizontal transfer path 7 extending perpendicularly to the vertical transfer path 6 is provided in the vicinity of a part of the semiconductor substrate 1. The signal charges stored in the signal storage unit 2, the blue photoelectric conversion unit 3 and the red photoelectric conversion unit 4 are sequentially read out to the vertical transfer path 6 and transferred along the vertical transfer path 6 as will be described later. After being transferred from the vertical transfer path 6 to the horizontal transfer path 7, it is output from the horizontal transfer path 7. By doing so, the stacked solid-state imaging device 10 can read R, G, and B color signals from the light received during imaging.

FIG. 2 is a cross-sectional view illustrating the configuration of the stacked solid-state imaging device of the present embodiment.
In the stacked solid-state imaging device 10, the signal storage unit 2, the blue photoelectric conversion unit 3, and the red photoelectric conversion unit 4 are formed on the upper surface portion of the semiconductor substrate 1. In the present embodiment, the semiconductor substrate 1 is an n-type semiconductor, and the p-well layer and the n region are formed in the photodiodes constituting the blue photoelectric conversion unit 3 and the red photoelectric conversion unit 4.

  On the upper surface of the semiconductor substrate 1, vertical transfer paths 6 are provided at intervals in the horizontal direction so as to correspond to the signal storage unit 2, the blue photoelectric conversion unit 3, and the red photoelectric conversion unit 4.

  A transfer electrode 17 is formed on the upper surface of the vertical transfer path 6. In addition, a light shielding film 18 is formed so as to cover the transfer electrode 17 in order to prevent smear from being generated by the light incident on the insulating layer 19 being applied to the vertical transfer path 6.

On the upper surface portion of the semiconductor substrate 1, an insulating layer 19 having optical transparency is laminated. In the insulating layer 19, a color filter 13 that transmits blue is provided above the stacking direction of the blue photoelectric conversion unit 3 (vertical direction in FIG. 2), and red is transmitted above the stacking direction of the red photoelectric conversion unit 4. A color filter 14 is provided. The transfer electrode 17, the light shielding film 18, and the color filters 13 and 14 are embedded in the insulating layer 19.

  A pixel electrode film 12 is formed on the upper surface of the insulating layer 19 so as to be divided for each pixel. These pixel electrode films 12 are electrically connected to the signal storage portion 2 provided on the semiconductor substrate 1 by columnar vertical wirings 16.

  On the pixel electrode film 12, a photoelectric conversion film 11 that is a transparent organic semiconductor is formed over the entire surface of the semiconductor substrate 1 as viewed from the light incident direction. A counter electrode 15 having optical transparency is formed on the surface of the photoelectric conversion film 11.

  When light enters the stacked solid-state imaging device 10, light in the green wavelength region of incident light is absorbed by the photoelectric conversion film 11, and photoelectric charges are generated in the photoelectric conversion film 11. Then, the photocharge is guided to the signal storage unit 2 through the vertical wiring 16 and is stored by applying a bias voltage to the counter electrode 15.

  Of the incident light, light in the blue and red wavelength regions passes through the photoelectric conversion film 11. The blue light passes through the color filter 13 and enters the blue photoelectric conversion unit 3, and signal charges corresponding to the amount of blue light are generated and accumulated in the blue photoelectric conversion unit 3. The red light passes through the color filter 14 and enters the red photoelectric conversion unit 4, and a signal charge corresponding to the amount of red light is generated and accumulated in the red photoelectric conversion unit 4.

  The signal charges of each color accumulated in the signal storage unit 2, the blue photoelectric conversion unit 3, and the red photoelectric conversion unit 4 are read out to the vertical transfer path 6 and transferred to the horizontal transfer path 7, via the horizontal transfer path 7. And output from the semiconductor substrate 1.

  In the stacked solid-state imaging device 10 according to the present embodiment, the pixel conversion films 12 are arranged at regular intervals, and the blue photoelectric conversion unit 3 and the red photoelectric conversion unit 4 are perpendicular to the semiconductor substrate 1 (see FIG. 1). When viewed from the front), the pixel electrode films 12 are disposed between the pixel electrode films 12. Then, the amount of light that passes through the photoelectric conversion film 11 and enters the blue photoelectric conversion unit 3 and the red photoelectric conversion unit 4 can pass through the pixel electrode film 12 as small as possible. For this reason, it can suppress that the light which should enter into the blue photoelectric conversion part 3 and the red photoelectric conversion part 4 resulting from permeate | transmitting the pixel electrode film | membrane 12 can be suppressed, and the light of the wavelength area | region of red and blue Utilization efficiency can be improved.

  Here, the points on the light incident side of the blue photoelectric conversion unit 3 and the red photoelectric conversion unit 4 are positioned between the pixel electrode films 12 when viewed from a direction perpendicular to the semiconductor substrate 1. Yes. 70% to 100% of each area on the light incident side in the blue photoelectric conversion unit 3 and the red photoelectric conversion unit 4 does not overlap the pixel electrode film 12 with respect to the light incident direction (front view direction in FIG. 1). Is preferred.

  Further, in the present embodiment, the configuration is such that incident light is received by the photoelectric conversion film 11 and photoelectric charges are accumulated, so that it is not necessary to directly irradiate the signal accumulation unit 2 provided on the semiconductor substrate 1 with light. Therefore, in the stacked solid-state imaging device 10 according to the present embodiment, as shown in FIG. 2, the surface area of the signal storage unit 2 in the light incident direction is set to the blue photoelectric conversion unit 3 or the red photoelectric conversion unit 4. It can be made smaller than each area.

  In the stacked solid-state imaging device 10 of this embodiment, a blue photoelectric conversion unit 3 and a red photoelectric conversion unit 4 are provided on a semiconductor substrate 1 and a photoelectric conversion film 11 that receives light in the green wavelength region is formed thereon. Although it was set as the structure, it is not limited to this. In the multilayer solid-state imaging device 10 including the following embodiments, the first photoelectric conversion unit and the second photoelectric conversion unit corresponding to two of the three primary colors are provided on the semiconductor substrate, respectively, and the wavelength of the other one color. A photoelectric conversion film that receives light in the region can be stacked over the semiconductor substrate.

  Next, a second embodiment according to the present invention will be described. In the embodiments described below, members having the same configuration / action as those already described are denoted by the same or corresponding reference numerals in the drawings, and description thereof is simplified or omitted.

FIG. 3 is a plan view of the stacked solid-state imaging device of the present embodiment, and FIG. 4 is a cross-sectional view illustrating the configuration of the stacked solid-state imaging device of the present embodiment.
The stacked solid-state imaging device 30 detects a light having a green wavelength by laminating a blue photoelectric conversion unit 33 and a red photoelectric conversion unit 34 on a semiconductor substrate 31 arranged in a two-dimensional form, and the semiconductor substrate 31. The photoelectric conversion film 41 is provided. Functions of the blue photoelectric conversion unit 33, the red photoelectric conversion unit 34, the signal storage unit 32, the pixel electrode film 42, the vertical wiring 46, the transfer electrode 47, and the light shielding film 48 provided on the semiconductor substrate 31 are illustrated in FIGS. This is the same as the first embodiment shown.

  As shown in FIG. 3, in the stacked solid-state imaging device 30 of the present embodiment, the pixel electrode film 42, the blue photoelectric conversion film 33, and the red photoelectric conversion film 34 have a rectangular shape perpendicular to the light incident direction. Has a surface. 3, the blue photoelectric conversion film 33 and the red photoelectric conversion film 34 are arranged so that the surfaces of the blue photoelectric conversion film 33 and the red photoelectric conversion film 34 are long in the vertical direction, and the surface of the pixel electrode film 42 is long in the left-right direction. Has been.

  As in the first embodiment, the stacked solid-state imaging device 30 according to the present embodiment includes pixels when the blue photoelectric conversion unit 33 and the red photoelectric conversion unit 34 are viewed from a direction perpendicular to the semiconductor substrate 31. They are respectively disposed between the electrode films 42. Further, the emphasis on the light incident side surface of the blue photoelectric conversion unit 33 and the red photoelectric conversion unit 34 is located between the pixel electrode films 42 when viewed from a direction perpendicular to the semiconductor substrate 31. As shown in FIG. 3, the pixel electrode film 42, the blue photoelectric conversion unit 33, and the red photoelectric conversion unit 34 may partially overlap with each other in the light incident direction.

  In addition, since the photoelectric conversion film 41 receives incident light and accumulates photocharges, the surface area of the signal storage unit 32 in the light incident direction is set to the blue photoelectric conversion unit 33 or the red photoelectric conversion unit 34. It can be made smaller than each area. At this time, as shown in FIG. 3, the vertical transfer path 36 is formed in a meandering state so as to be close to the signal storage unit 32, the blue photoelectric conversion unit 33, and the red photoelectric conversion unit 34, respectively.

  The stacked solid-state imaging device 30 of the present embodiment can suppress the absorption of light that should enter the blue photoelectric conversion unit 33 and the red photoelectric conversion unit 34 due to transmission through the pixel electrode film 42, The utilization efficiency of light in the red and blue wavelength regions can be improved.

Next, a third embodiment according to the present invention will be described.
FIG. 5 is a cross-sectional view illustrating the configuration of the stacked solid-state imaging device of the present embodiment. The configuration of the multilayer solid-state imaging device of this embodiment is basically the same as that of the first multilayer solid-state imaging device shown in FIGS. 1 and 2, and different configurations will be described below.

  As shown in FIG. 5, the stacked solid-state imaging device 50 has a convex surface on the light incident side on each of the upper surface of the color filter 13 that transmits the blue wavelength region and the color filter 14 that transmits the red wavelength region. And a microlens 51 having a flat bottom surface. The area of the lower surface of the microlens 51 is preferably larger than the area of the upper surface of the color filters 13 and 14.

  According to the stacked solid-state imaging device 50 of the present embodiment, it is possible to suppress absorption of light to be incident on the blue photoelectric conversion unit 3 and the red photoelectric conversion unit 4 through the pixel electrode film 12, and Light that has entered the insulating layer 19 without passing through the pixel electrode film 12 is condensed by irradiating the microlens 51, and is emitted to the color filters 13 and 14. For this reason, even if light incident obliquely to the light incident surface of the multilayer solid-state imaging device 50 is incident on the insulating layer 19 without passing through the pixel electrode film 12, the color filters 13 and 14 are formed by the microlens 51. Therefore, the light utilization efficiency is further improved.

In addition, this invention is not limited to embodiment mentioned above, A suitable deformation | transformation, improvement, etc. are possible.
For example, in the solid-state imaging device 10 shown in FIG. 2, a flange-shaped light shielding portion that extends toward the semiconductor substrate 1 at the edge of the image electrode film 12 in order to prevent light from entering the signal storage portion 2. May be provided. Alternatively, a light blocking layer may be formed on the entire surface of the semiconductor substrate 1 and the vertical transfer path 6 to prevent light from entering the signal storage unit 2.

It is a top view which shows 1st Embodiment of a laminated | stacked solid-state imaging device. It is sectional drawing explaining the structure of the laminated | stacked solid-state imaging device of 1st Embodiment. It is a top view of 2nd Embodiment of a laminated | stacked solid-state imaging device. It is sectional drawing explaining the structure of the laminated | stacked solid-state imaging device of 2nd Embodiment. It is sectional drawing explaining the structure of the lamination type solid-state imaging device of 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,31 Semiconductor substrate 2,32 Signal storage part 3,33 Blue photoelectric conversion part 4,34 Red photoelectric conversion part 6,36 Vertical transfer path 7,37 Horizontal transfer path 10,30,50 Stack type solid-state imaging device 11,41 Photoelectric conversion film 12, 42 Pixel electrode film 13, 14, 43, 44 Color filter 51 Micro lens

Claims (4)

A semiconductor substrate in which a blue photoelectric conversion unit for detecting light of a blue wavelength and a red photoelectric conversion unit for detecting light of a red wavelength are arranged two-dimensionally, and the semiconductor substrate is stacked on the semiconductor substrate, and the green wavelength A stacked solid-state imaging device comprising a photoelectric conversion film for detecting the light of
The photoelectric conversion film is arranged so as to cover the blue photoelectric conversion unit and the red photoelectric conversion unit,
A pixel electrode film disposed at a constant interval for each pixel is connected to the photoelectric conversion film, and the blue photoelectric conversion unit and the red photoelectric conversion unit are viewed from a direction perpendicular to the semiconductor substrate. A stacked solid-state imaging device, wherein the stacked-type solid-state imaging device is disposed between the pixel electrode films.   The stacked solid-state imaging device according to claim 1, wherein the photoelectric conversion film is a transparent organic semiconductor.   A charge storage unit is connected to the photoelectric conversion film, and an area of the charge storage unit is smaller than each area of the blue photoelectric conversion unit and the red photoelectric conversion unit in a light incident direction view. Item 3. The stacked solid-state imaging device according to Item 1 or 2. A color filter that transmits incident light is provided above the blue photoelectric conversion unit and the red photoelectric conversion unit and below the photoelectric conversion film , respectively, and a microlens is provided on the light incident side surface of the color filter. The stacked solid-state imaging device according to claim 1, wherein the stacked solid-state imaging device is provided.

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