JP4320270B2 - Photoelectric conversion film stack type solid-state imaging device - Google Patents

Description

  The present invention relates to a photoelectric conversion film stacked solid-state imaging device configured by stacking a photoelectric conversion film on a semiconductor substrate on which a signal readout circuit is formed.

  As a prototype element of the photoelectric conversion film laminated solid-state imaging device, for example, there is one described in Patent Document 1 below. In this solid-state imaging device, three photosensitive layers are stacked on a semiconductor substrate, and red (R), green (G), and blue (B) electrical signals detected in each photosensitive layer are transmitted to the surface of the semiconductor substrate. Reading is performed by the MOS circuit formed in the circuit.

  A solid-state imaging device having such a configuration has been proposed in the past. Thereafter, a large number of light receiving portions (photodiodes) are integrated on the surface portion of the semiconductor substrate, and red (R), green (G), and blue are integrated on each light receiving portion. The CCD type image sensor and CMOS type image sensor in which the color filters of each color (B) are laminated have advanced remarkably, and now, an image sensor in which millions of light receiving parts (pixels) are integrated on one chip is used as a digital still camera. It comes to be installed.

  However, the CCD type image sensor and the CMOS type image sensor have progressed to their limits, and the aperture size of one light receiving part is about 2 μm, which is close to the wavelength order of incident light, and the manufacturing yield is poor. Faced with the problem.

  In addition, the upper limit of the amount of photocharge accumulated in one miniaturized light receiving portion is as small as about 3000 electrons, which makes it difficult to express 256 gradations neatly. For this reason, it is difficult to expect an image sensor more than the current type in the CCD type or the CMOS type in terms of image quality and sensitivity.

  Therefore, as a solid-state imaging device that solves these problems, the solid-state imaging device proposed in Patent Document 1 has attracted attention, and image sensors described in Patent Document 2 and Patent Document 3 are newly proposed. It is becoming like this.

  In the image sensor described in Patent Document 2, ultrafine particles of silicon are dispersed in a medium to form a photoelectric conversion layer, and a plurality of photoelectric conversion layers having different ultrafine particle sizes are stacked on a semiconductor substrate. In each photoelectric conversion layer, electrical signals corresponding to the received light amounts of red, green and blue are generated.

  The same applies to the image sensor described in Patent Document 3, in which three nanosilicon layers having different particle diameters are stacked on a semiconductor substrate, and red, green, and blue electrical signals detected by each nanosilicon layer are detected. Is read out to the storage diode formed on the surface portion of the semiconductor substrate.

  FIG. 5 is a schematic cross-sectional view of two pixels of this conventional photoelectric conversion film laminated solid-state imaging device. In FIG. 5, on the surface portion of a P well layer 1 formed on an n-type silicon substrate, a high-concentration impurity region 2 for red signal storage, a MOS circuit 3 for reading red signals, and a high-level signal for green signal storage. A concentration impurity region 4, a green signal readout MOS circuit 5, a blue signal storage high concentration impurity region 6, and a blue signal readout MOS circuit 7 are formed.

  Each MOS circuit 3, 5, 6 is composed of a source and drain impurity region formed on the surface of the semiconductor substrate and a gate electrode formed through a gate insulating film 8. An insulating film 9 is laminated and planarized on the gate insulating film 8 and the gate electrode, and a light shielding film 10 is laminated thereon. Since the light shielding film is often formed of a metal thin film, an insulating film 11 is further formed thereon.

  The signal charges accumulated in the color signal accumulation high concentration impurity regions 2, 4, 6 described above are read out to the outside by the MOS circuits 3, 5, 7.

  On the insulating film 11 shown in FIG. 5, the counter electrode film 12 divided for each pixel is formed. The counter electrode film 12 for each pixel is electrically connected to the red signal storage high concentration impurity region 2 for each pixel by the columnar electrode 13. This columnar electrode 13 is electrically insulated from areas other than the counter electrode film 12 and the high concentration impurity region 2.

  A red detection photoelectric conversion film 14 is formed on each counter electrode film 12, and a transparent common electrode film 15 is formed on the photoelectric conversion film 14. The photoelectric conversion film 14 and the common electrode film 15 do not need to be provided separately for each pixel, and are formed in a single structure on the entire surface of the semiconductor substrate.

  Similarly, a transparent insulating film 16 is formed on the common electrode film 15, and a transparent counter electrode film 17 divided for each pixel is formed thereon. The counter electrode film 17 for each pixel and the corresponding high-concentration impurity region 4 for storing green signal for each pixel are electrically connected by a columnar electrode 18. This columnar electrode 18 is electrically insulated from areas other than the counter electrode film 17 and the high concentration impurity region 4. A green color photoelectric conversion film 19 is formed on the counter electrode film 17 in the same configuration as the photoelectric conversion film 14, and a transparent common electrode film 20 is formed thereon.

  A transparent insulating film 21 is formed on the common electrode film 20, and a counter electrode film 22 divided for each pixel is formed on the transparent insulating film 21. The counter electrode film 22 for each pixel is electrically connected by the columnar electrode 23 to the blue signal storage high concentration impurity region 6 for each corresponding pixel. This columnar electrode 23 is electrically insulated from areas other than the counter electrode film 22 and the high concentration impurity region 6. A blue detection photoelectric conversion film 23 is formed on the counter electrode film 21, a transparent common electrode film 24 is formed on the photoelectric conversion film 23, and a transparent protective film 25 is formed on the uppermost layer.

  When incident light is incident on the solid-state image sensor, photoelectric charges corresponding to the amounts of incident light of blue light, green light, and red light are excited in the photoelectric conversion films 23, 19, 14, and the common electrode films 24, 20, 15 are excited. And the counter electrode films 22, 17, 12 are applied with a voltage, so that respective photocharges flow into the high-concentration impurity regions 2, 4, 6. , Green signal and red signal.

JP 58-103165 A Japanese Patent No. 3405099 Japanese Patent Laid-Open No. 2002-83946

  In the photoelectric conversion film stacked solid-state imaging device having the configuration shown in FIG. 5, on the insulating film 11 on the surface of the semiconductor substrate, in the illustrated example, the counter electrode film 12, the red photoelectric conversion film 14, the common electrode film 15, and the insulation are provided. The film 16, the counter electrode film 17, the green photoelectric conversion film 19, the common electrode film 20, the insulating film 21, the counter electrode film 22, the blue photoelectric conversion film 23, the common electrode film 24, and the protective film 25, a total of 12 layers It is necessary to stack the films.

  When manufacturing a photoelectric conversion film laminated solid-state imaging device, it is necessary to reduce the number of manufacturing steps in order to improve the manufacturing yield and reduce the manufacturing cost. If one layer can be reduced among the above-mentioned 12 layers, the production yield is improved and the production cost is reduced.

  An object of the present invention is to provide a photoelectric conversion film stacked solid-state imaging device capable of reducing the manufacturing cost and improving the manufacturing yield.

The photoelectric conversion film stacked solid-state imaging device of the present invention includes a common electrode film and a pixel in which a plurality of photoelectric conversion films are stacked on a semiconductor substrate on which a signal readout circuit is formed, and each photoelectric conversion film is not divided for each pixel. In the photoelectric conversion film stack type solid-state imaging device, the common charge provided in the first photoelectric conversion film is sandwiched between the counter electrode films divided for each and the photoelectric charges generated in each photoelectric conversion film are taken out from the counter electrode film share and the common electrode film provided on the electrode film and the second photoelectric conversion layer, the first photoelectric conversion layer together with the under the common electrode film for co first photoelectric conversion layer is stacked The counter electrode film divided for each pixel is stacked below, the second photoelectric conversion film is stacked on the shared common electrode film, and each pixel is formed on the second photoelectric conversion film. The counter electrode film divided into Characterized in that it is.

  With this configuration, the number of stacked layers on the semiconductor substrate can be reduced, the manufacturing cost can be reduced, and the manufacturing yield can be improved.

The photoelectric conversion film stack type solid-state imaging device of the present invention includes three photoelectric conversion films for red detection, green detection, and blue detection in order from the shortest detection wavelength in order from the top, and are adjacent to each other among the three photoelectric conversion films. The common electrode film is provided between at least two photoelectric conversion films, and the two photoelectric conversion films share the common electrode film .

  With this configuration, it is possible to reduce the manufacturing cost and improve the manufacturing yield of the photoelectric conversion film stacked solid-state imaging device capable of detecting the three primary colors.

The photoelectric conversion film laminated solid-state imaging device of the present invention includes four photoelectric conversion films for red detection, green detection, blue detection, and emerald color detection from the top in order of short detection wavelength. The common electrode film is provided between at least two adjacent photoelectric conversion films, and the two photoelectric conversion films share the common electrode film .

  With this configuration, it is possible to reduce the manufacturing cost and improve the manufacturing yield of the photoelectric conversion film stacked solid-state imaging device capable of color reproduction according to human visibility.

  In the photoelectric conversion film stacked solid-state imaging device of the present invention, the common electrode film provided on the lowermost photoelectric conversion film stacked on the semiconductor substrate is provided under the photoelectric conversion film and the common electrode film is shielded from light. It is also used as a membrane.

  Also with this configuration, the number of manufacturing steps can be reduced, and a photoelectric conversion film stacked solid-state imaging device with a high manufacturing yield can be obtained at low cost.

  According to the present invention, it is possible to reduce the number of film forming and stacking steps of the photoelectric conversion film stack type solid-state imaging device, so that it is possible to reduce the manufacturing cost and improve the manufacturing yield.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of two pixels of a photoelectric conversion film stacked solid-state imaging device according to an embodiment of the present invention. Among the structures of the photoelectric conversion film laminated solid-state imaging device of the present embodiment, the structure of the semiconductor substrate portion of the photoelectric conversion film laminated solid-state imaging device described in FIG. 5 is the same. That is, the structure up to the insulating film 11 is the same.

  In FIG. 1, a counter electrode film 31 divided for each pixel is formed on an insulating film 11. The counter electrode film 31 is electrically connected to the high concentration impurity region 2 of the corresponding pixel by the columnar electrode 32. This columnar electrode 32 is electrically insulated from other than the counter electrode film 31 and the high concentration impurity region 2.

  A red detecting photoelectric conversion film 33 is laminated on the entire surface of the counter electrode film 31 without being divided for each pixel, and a transparent common electrode film 34 having a single structure is similarly formed thereon. Are laminated.

  In the present embodiment, a single green detection photoelectric conversion film 35 is laminated on the common electrode film 34 without being divided for each pixel, and a transparent counter electrode divided for each pixel is formed thereon. A film 36 is stacked. The counter electrode film 36 is electrically connected to the high concentration impurity region 4 of the corresponding pixel by a columnar electrode 37. This columnar electrode 37 is electrically insulated except for the counter electrode film 36 and the high concentration impurity region 4.

  A transparent insulating film 38 is laminated on the counter electrode film 36, and a transparent counter electrode film 39 divided for each pixel is laminated thereon. Each counter electrode film 39 is electrically connected to the high concentration impurity region 6 of the corresponding pixel by a columnar electrode 40. This columnar electrode 40 is electrically insulated from areas other than the counter electrode film 39 and the high concentration impurity region 6.

  On the counter electrode film 39, a single-layer blue detection photoelectric conversion film 41 is laminated without being divided for each pixel, and a single-layer transparent common electrode film 42 is similarly laminated thereon. A transparent protective film 43 is laminated on the uppermost layer.

  The photoelectric conversion film laminated solid-state imaging device of this embodiment uses only two common electrode films regardless of the configuration for detecting the color signals of three colors of red (R), green (G), and blue (B). Two common electrode films 42 and 34 are connected to the bias voltage Vb.

  That is, in the present embodiment, the counter electrode film 31, the red photoelectric conversion film 33, the common electrode film 34, the green color detection photoelectric conversion film 35, the counter electrode film 36, and the insulating film are formed on the insulating film 11 on the semiconductor substrate side. 38, a counter electrode film 39, a blue color detection photoelectric conversion film 41, a common electrode film 42, a protective film 43, and a total of 10 layers are laminated, and a lamination process for two layers as compared with the configuration of FIG. Is omitted.

  In the photoelectric conversion film stacked solid-state imaging device having such a configuration, when light from a subject is incident, a photoelectric charge corresponding to the amount of incident blue light is generated in the photoelectric conversion film 41, and the common electrode film 42 and the counter electrode film 39. When a voltage is applied between the two, a blue light photoelectric charge flows into the high concentration impurity region 6.

  Similarly, a photoelectric charge corresponding to the amount of green light in the incident light is generated in the photoelectric conversion film 35, and when a voltage is applied between the common electrode film 34 and the counter electrode film 36, the green light photoelectric charge is generated. Flows into the high concentration impurity region 4.

  Similarly, a photoelectric charge corresponding to the amount of red light in the incident light is generated in the photoelectric conversion film 33, and when a voltage is applied between the common electrode film 34 and the counter electrode film 31, a green light photoelectric charge is generated. Flows into the high concentration impurity region 2.

  As described above, according to the present embodiment, since signals of three colors of red (R), green (G), and blue (B) can be read out and the number of manufacturing processes can be reduced, the manufacturing yield can be increased. The manufacturing cost can be reduced.

  In the example shown in FIGS. 5 and 1, for example, light incident obliquely to the photoelectric conversion film for detecting blue (B) of the pixel i has the green (G) and red (R) photoelectric of the adjacent pixel i + 1. There is a possibility that crosstalk occurs between the pixels by entering the conversion film. However, since the entire film thickness of the configuration of FIG. 1 is reduced by two layers compared to FIG. There is also an advantage that color reproducibility is improved.

  In this embodiment, the signal is read out by the MOS circuit formed on the semiconductor substrate. However, the charges accumulated in the high-concentration impurity regions 2, 4 and 6 for color signal accumulation are the same as those in the conventional CCD image sensor. Further, it is also possible to adopt a configuration in which it is moved along the vertical transfer path and read out along the horizontal transfer path.

  The embodiment shown in FIG. 1 is an example of a photoelectric conversion film stacked solid-state imaging device that detects three primary colors of red (R), green (G), and blue (B), but has a configuration that can detect four colors. It is also possible to do. FIG. 2 is a schematic cross-sectional view of two pixels of a photoelectric conversion film stacked solid-state imaging device that detects four colors, and is an intermediate color (GB: emerald) of green (G) and blue (B) with respect to the configuration of FIG. The difference is that the photoelectric conversion film 50 and the electrodes for detecting the color are formed in the order of lamination described below.

  For example, an advantage of detecting an emerald (GB) color having a wavelength of 480 to 520 nm is to correct red according to human visual sensitivity. As shown in FIG. 3 as α, β, and γ, human visual sensitivity is negative in green (G), red (R), and blue (B). For this reason, even if color reproduction is performed by detecting only positive sensitivities of R, G, and B with a solid-state imaging device, an image seen by humans cannot be reproduced. Therefore, β having the greatest negative sensitivity, that is, negative red sensitivity is detected by the photoelectric conversion film 50, and the sensitivity to human red is obtained by subtracting this negative sensitivity from the red sensitivity detected by the photoelectric conversion film 31. Can be reproduced.

  In FIG. 2, the process until the insulating film 38 is formed is the same as that of the embodiment of FIG. In this embodiment, a transparent counter electrode film 49 divided for each pixel for emerald color detection is formed on the insulating film 38. Each counter electrode film 49 is electrically connected to a high-concentration impurity region 52 for GB color provided on the surface of the semiconductor substrate corresponding to each pixel by a columnar electrode 51. This columnar electrode 52 is electrically insulated from areas other than the counter electrode film 49 and the high concentration impurity region 52, and the signal charge amount of the high concentration impurity region 52 is a MOS circuit provided adjacent to the region 52. 53.

  On each counter electrode film 49, a photoelectric conversion film 50 for emerald (GB) color detection is laminated in a single configuration without being divided for each pixel, and a transparent common electrode film 42 is formed thereon. Formed with configuration.

  A blue (B) detection photoelectric conversion film 41 is laminated on the common electrode film 42, and a transparent counter electrode film 39 divided for each pixel is laminated thereon. Each counter electrode film 39 is electrically connected to the high concentration impurity region 6 of the corresponding pixel by a columnar electrode 40. This columnar electrode 40 is electrically insulated from areas other than the counter electrode film 39 and the high concentration impurity region 6. A transparent protective film 43 is formed on the uppermost layer.

  When the photoelectric conversion film laminated solid-state imaging device that detects four colors of blue, emerald, green, and red is configured in the same manner as for the three colors shown in FIG. 5, a photoelectric conversion film for GB color and a common electrode film, An insulating film provided between the counter electrode film and other layers is added, and a total of 16 layers are required on the insulating film 11. However, by adopting the laminated structure of the present embodiment, the total number of layers becomes 12 and the number of steps for laminating four layers is reduced.

  FIG. 4 is a diagram illustrating a stacked structure of another embodiment of a photoelectric conversion film stacked solid-state imaging device that detects four colors of blue (B), emerald color (GB), green (G), and red (R). . The blue detection photoelectric conversion film 41, the GB color detection photoelectric conversion film 50, the green color detection photoelectric conversion film 35, the red color detection photoelectric conversion film 33, and the red detection photoelectric conversion film 33 are provided in this order from the top in the shortest wavelength order. Although the form is the same, the stacking order of the common electrode film and the counter electrode film is different.

  That is, in this embodiment, the common electrode film 60, the red detection photoelectric conversion film 33, the red counter electrode film 31, the insulating film 61, the green counter electrode film 36, and the green detection photoelectric conversion are formed on the insulating film 11. Film 35, common electrode film 62, GB color detection photoelectric conversion film 50, GB color counter electrode film 49, insulating film 63, blue counter electrode film 39, blue color detection photoelectric conversion film 41, common electrode film 64, protection The films 43 are stacked in this order.

  Compared to the embodiment shown in FIG. 2, in this embodiment, a total of 14 layers (12 layers in FIG. 2) need to be stacked on the insulating film 11. However, since the common electrode film 60 is provided in the lowermost layer, the light shielding film can also be used by making the common electrode film 60 an opaque electrode film. That is, the light shielding film 10 shown in FIG. 2 can be eliminated, and therefore the insulating film 9 and the insulating film 11 can be combined.

  As described above, according to the present embodiment, in the solid-state imaging device in which a plurality of layers of photoelectric conversion films are stacked, the photoelectric conversion films are stacked above and below the common electrode film. It is possible to reduce the manufacturing cost and the manufacturing yield.

  Since the photoelectric conversion film laminated solid-state imaging device according to the present invention can achieve a low cost and a high production yield, it can be used in place of a conventional CCD type or CMOS type image sensor.

It is a cross-sectional schematic diagram for 2 pixels of the photoelectric conversion film laminated | stacked solid-state image sensor of the 3 layer structure which concerns on the 1st Embodiment of this invention. It is a cross-sectional schematic diagram for 2 pixels of the photoelectric conversion film laminated | stacked solid-state image sensor of the 4 layer structure which concerns on the 2nd Embodiment of this invention. It is a graph which shows human visibility. It is a cross-sectional schematic diagram for 2 pixels of the photoelectric conversion film laminated | stacked solid-state image sensor of the 4 layer structure which concerns on the 3rd Embodiment of this invention. It is a cross-sectional schematic diagram for two pixels of a conventional photoelectric conversion film laminated solid-state imaging device having a three-layer structure.

Explanation of symbols

1 P well layer (semiconductor substrate)
2, 4, 6, 52 High-concentration impurity regions 3, 5, 7, 53 MOS circuit 8 Gate insulating films 9, 11, 38, 61, 63 Insulating films 31, 36, 39, 49 Counter electrode films 34, 42, 60 , 62, 64 Common electrode film 33, 35, 41, 50 Photoelectric conversion film 43 Protective film

Claims (4)

A plurality of photoelectric conversion films are stacked on a semiconductor substrate on which a signal readout circuit is formed, and each photoelectric conversion film is sandwiched between a common electrode film that is not divided for each pixel and a counter electrode film that is divided for each pixel, In the photoelectric conversion film stacked solid-state imaging device in which the photoelectric charge generated in each photoelectric conversion film is extracted from the counter electrode film, the common electrode film provided on the first photoelectric conversion film and the common provided on the second photoelectric conversion film The electrode film is shared , the first photoelectric conversion film is stacked under the shared common electrode film, and the counter electrode film divided for each pixel under the first photoelectric conversion film The second photoelectric conversion film is stacked on the shared common electrode film, and the counter electrode film divided for each pixel is stacked on the second photoelectric conversion film. Photoelectric conversion film stack type solid The image pickup device. Three photoelectric conversion films for red detection, green detection, and blue detection are provided in order from the shortest detection wavelength in the order from the top to the common electrode film between at least two adjacent photoelectric conversion films among the three photoelectric conversion films. The photoelectric conversion film stack type solid-state imaging device according to claim 1 , wherein the common electrode film is shared by the two photoelectric conversion films. Four photoelectric conversion films for red color detection, green color detection, blue color detection, and emerald color detection are provided from the top in the order of short detection wavelength, and between at least two adjacent photoelectric conversion films among the four photoelectric conversion films. The photoelectric conversion film stacked solid-state imaging device according to claim 1, wherein the common electrode film is provided, and the two photoelectric conversion films share the common electrode film .   The common electrode film provided on the lowermost photoelectric conversion film laminated on the semiconductor substrate is provided below the photoelectric conversion film, and the common electrode film is also used as a light shielding film. The photoelectric conversion film laminated solid-state imaging device according to claim 3.

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