JP2013258168A - Solid-state imaging element, and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-state imaging element capable of miniaturizing pixels while securing a degree of freedom of a design of a signal reading circuit.SOLUTION: In a solid-state imaging element, a color filter layer CF having color filters 21 of a plurality of different colors is arranged on a plurality of photoelectric conversion parts 17 two-dimensionally arranged on a substrate 1 so that each color filter 21 corresponds to each photoelectric conversion part 17 one by one. Among the color filters 21 of the plurality of colors and the plurality of photoelectric conversion parts 17, a color filter 21 of a predetermined color and a photoelectric conversion part 17 corresponding to the color filter 21 have the largest area. An area of each signal reading circuit part 11 provided to correspond to each photoelectric conversion part 17 is set to be smaller than the area of the largest photoelectric conversion part 17 and larger than the area of the smallest photoelectric conversion part 17.

Description

  The present invention relates to a solid-state imaging device including a photoelectric conversion unit that generates charges when irradiated with light, and an imaging apparatus including the solid-state imaging device.

  As an image sensor used for a digital still camera, a digital video camera, a mobile phone camera, an endoscope camera, etc., pixels including photodiodes are arranged on a semiconductor substrate such as a silicon (Si) chip, Solid-state imaging devices (so-called CCD sensors and CMOS sensors) that acquire signal charges corresponding to photoelectrons generated in a photodiode with a CCD type or CMOS type readout circuit are widely known.

  In recent years, pixel miniaturization of solid-state imaging devices has progressed. However, pixel miniaturization generally involves a problem that the S / N of an image is lowered because the number of incident photons decreases as the pixel size decreases. The S / N of an image can be broadly divided into luminance S / N and color S / N. The luminance S / N is a component that mainly appears in the roughness of the image, and the color S / N is a component that mainly appears in color separation and color reproduction. Of these, human vision is sensitive to a decrease in luminance S / N, and a decrease in color S / N is less noticeable than a decrease in luminance S / N. Therefore, suppressing the decrease in luminance S / N during pixel miniaturization leads to the suppression of image quality deterioration. For example, in a solid-state imaging device having an RGB color filter, a method for improving the image quality by making the photoelectric conversion unit of the G pixel larger than the R and B pixels has been proposed (Patent Documents 1 and 2).

  On the other hand, for high image quality and pixel miniaturization, a photoelectric conversion unit including a pair of electrodes and a photoelectric conversion layer sandwiched between them is provided above the silicon substrate, and the charges generated in the photoelectric conversion layer are transferred to the pair of electrodes. Attention has been focused on a photoelectric conversion layer stacked type solid-state imaging device in which a signal is transferred from one of the electrodes to a silicon substrate and accumulated, and a signal corresponding to the accumulated charge is read out by a signal readout circuit formed on the silicon substrate. For example, Patent Document 3 proposes a stacked solid-state imaging device including an organic photoelectric conversion film.

JP 2007-288294 A JP 2010-10370 A JP 2011-187663 A

  The solid-state imaging devices described in Patent Documents 1 and 2 have a configuration in which a photodiode and a signal readout circuit that accumulates and reads out signal charges corresponding to photoelectrons generated in the photodiode are provided on the same surface of a silicon substrate. Since the photodiode and the signal readout circuit are provided on the same plane, it is necessary to change the layout of the signal readout circuit when the size and shape of the photodiode are changed. Is low. As a result, since the photodiode and the signal readout circuit cannot be optimized, the S / N reduction due to the area of the photodiode abruptly decreasing with pixel miniaturization and the layout of the signal readout circuit. However, it is difficult to achieve sufficient miniaturization while maintaining a high-definition image.

  In view of the above circumstances, the present invention provides a solid-state imaging device capable of suppressing a reduction in luminance S / N accompanying pixel miniaturization and capable of laying out photodiodes and signal readout circuits with a high degree of freedom, and the solid-state imaging device. An object of the present invention is to provide an imaging apparatus provided.

A solid-state imaging device of the present invention is a two-dimensionally arranged on a substrate, a plurality of photoelectric conversion units that generate a signal charge according to the amount of incident light,
An accumulation unit for accumulating charges generated in the photoelectric conversion unit and an output circuit for outputting a voltage corresponding to the signal charge of the accumulation unit are provided for each photoelectric conversion unit below the plurality of photoelectric conversion units on the substrate. A signal readout circuit unit,
On the plurality of photoelectric conversion units, color filter layers having different color filters are arranged such that each color filter corresponds to each photoelectric conversion unit in a 1: 1 ratio.
The area in plan view of the color filter and the photoelectric conversion unit corresponding to the color filter is determined for each color, and the color filter of a predetermined color among a plurality of colors and the area where the photoelectric conversion unit corresponding to the color filter is the largest Have
The area of each signal readout circuit unit is smaller than the area of the largest photoelectric conversion unit and larger than the area of the smallest photoelectric conversion unit.

  In the above, it is desirable that the predetermined color is a color having the highest visibility or the largest contribution to the luminance S / N among the plurality of colors.

“Visibility” represents the degree of strength with which the human eye feels light at each wavelength. Humans have different light intensity for each wavelength, and in bright places, light with a wavelength near 555 nm is felt most intensely. Here, it conforms to the standard relative luminous sensitivity established in 1924 by the CIE (International Commission on Illumination).
That is, when a general RGB (red, green, blue) filter is used, the G color including 555 nm is the color with the highest visibility.

  In addition, when converting the color signal from the photoelectric conversion unit of each color of RGB into a signal for displaying on various image display devices, the color signal is used as a luminance signal (Y) and a color difference signal (UV). All color signals contribute to the luminance signal (Y) at a predetermined ratio, and G having the largest contribution ratio (ratio) at that time has the largest contribution to the luminance S / N. For this reason, in the case of an RGB filter, the predetermined color is preferably G.

  On the other hand, in the case of a WRGB filter in which W (white) is added to RGB, a W signal from a pixel having a W filter that transmits light of all colors has the highest S / N. For this reason, it is common to use signal processing that creates a luminance signal based on the W signal and creates a color difference signal from the RGB signal. Therefore, in the case of a WRGB filter, it is preferable that the predetermined color is W.

  In the solid-state imaging device of the present invention, when the plurality of different colors are red, green and blue, the green color filter among the plurality of color filters and the photoelectric conversion provided under the green color filter The part preferably has the largest area.

  In the solid-state imaging device of the present invention, when the plurality of different colors are white, red, green, and blue, the white color filter and the white color filter are provided below the white color filter. It is preferable that the photoelectric conversion part to have the largest area.

  In the solid-state imaging device of the present invention, the photoelectric conversion unit includes a photoelectric conversion layer, a pixel electrode partitioned in units of photoelectric conversion units, and a counter electrode provided to face the pixel electrode with the photoelectric conversion layer interposed therebetween. The counter electrode may be a common electrode for all the photoelectric conversion units.

  The photoelectric conversion layer is preferably a common film for all photoelectric conversion units.

  Moreover, it is preferable that a photoelectric converting layer contains an organic photoelectric converting film.

  In addition, the storage unit in the signal readout circuit unit provided for each photoelectric conversion unit is adjusted in capacity so that when a white light source is imaged, the plurality of photoelectric conversion units are saturated with the same amount of light. preferable.

  An image pickup apparatus according to the present invention includes the solid-state image pickup element.

  According to the solid-state imaging device and the imaging apparatus of the present invention, the color filters of a plurality of colors and the area of the photoelectric conversion unit corresponding to each color filter are determined for each color, of which the color filter of a predetermined color and the color filter thereof The area of the photoelectric conversion unit corresponding to is maximized, the signal readout circuit unit is arranged below the photoelectric conversion unit, and the area of each signal readout circuit unit is made to correspond to the area of each photoelectric conversion unit 1: 1. Instead, it is smaller than the area of the largest photoelectric conversion unit and larger than the area of the smallest photoelectric conversion unit, so compared with the case where the signal readout circuit unit is arranged on the same plane as the photoelectric conversion unit. Can alleviate layout restrictions.

  Among the color filters of a plurality of colors and the plurality of photoelectric conversion units, the color filter having the highest visibility or the color filter having the largest contribution to the luminance S / N and the photoelectric conversion unit corresponding to the color filter are the most. In the case of having a large area, it is possible to suppress a decrease in luminance S / N during pixel miniaturization.

Sectional schematic diagram which shows a part of pixel area | region in embodiment of the solid-state image sensor of this invention The figure which shows the circuit structure of the pixel part in embodiment of the solid-state image sensor of this invention. Plan view showing an example of color filter layout FIG. 3A is a plan view showing a signal readout circuit layout corresponding to the color filter layout shown in FIG. 3A Plan view showing another example of color filter layout FIG. 4A is a plan view showing an example of a signal readout circuit layout corresponding to the color filter layout shown in FIG. 4A FIG. 4A is a plan view showing another example of a signal readout circuit layout for the color filter layout shown in FIG. 4A. The figure which shows the whole structure of embodiment of the solid-state image sensor of this invention. Sectional schematic diagram which shows a part of pixel area | region in the example of a design change of embodiment of the solid-state image sensor of this invention The top view which shows arrangement | positioning of the pixel electrode of a photoelectric conversion part, and a counter electrode Plan view showing an example of color filter layout in a design change example The top view which shows typically arrangement | positioning of the signal readout circuit and arrangement | positioning of a photoelectric conversion part in a design change example

Hereinafter, embodiments of a solid-state imaging device of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing a part of an imaging unit (pixel region) of the solid-state imaging device 100 of the present embodiment.

  As shown in FIG. 1, the imaging unit of the solid-state imaging device 100 includes a semiconductor circuit board 1, an interlayer insulating layer 5 on the semiconductor circuit board 1, and a wiring layer 6 disposed in the insulating layer 5. A plurality of pixel electrodes (lower electrodes) 12 (12r, 12g, 12b) arranged in a dimension, a photoelectric conversion layer 14 made of an organic material commonly formed on the plurality of pixel electrodes 12, and a photoelectric conversion layer 14 and a counter electrode 16 facing a plurality of pixel electrodes formed on the electrode 14. Further, a transparent protective film 18 is laminated on the counter electrode 16, and the color filters 21 (21 r, 21 g, 21 b) of a plurality of different colors (three colors in the present embodiment) are formed on the protective film 18. ) Provided with a color filter layer CF.

  One pixel electrode 12, the photoelectric conversion layer 14 on the pixel electrode 12, and the counter electrode 16 constitute one photoelectric conversion unit 17 (17r, 17g, 17b). The photoelectric conversion layer in the gap between adjacent pixel electrodes also contributes to photoelectric conversion, and the center line between adjacent pixel electrodes (broken line A in FIG. 1) becomes a boundary between adjacent photoelectric conversion elements.

  The color filter layer CF corresponds to one color filter for one photoelectric conversion unit, and is arranged so that both areas coincide in plan view. The area of the photoelectric conversion unit in plan view and the color filter in plan view The areas at are almost the same.

  On the surface layer of the semiconductor circuit substrate 1, a signal readout including an accumulation unit for accumulating charges generated in each photoelectric conversion unit 17 (17r, 17g, 17b) and an output circuit for outputting a voltage corresponding to the signal charge of the accumulation unit The circuit unit 11 (11r, 11g, 11b) is provided. One pixel unit 20 (20R, 20G, 20B) includes one photoelectric conversion unit 17 (17r, 17g, 17b), and a substrate surface layer portion below the photoelectric conversion unit 17 The signal readout circuit unit 11 (11r, 11g, 11b) formed in the above and each color filter 21 (21r, 21g, 21b) disposed on the photoelectric conversion unit. In addition, r, g, and b at the end of the reference numerals shown in the present specification and the drawings respectively indicate elements constituting the red pixel portion 20R, the green pixel portion 20G, and the blue pixel portion 20B, respectively. In the description, when it is not necessary to distinguish colors, the trailing r, g, and b may be omitted.

  The pixel electrode 12 is a thin film electrode divided for each photoelectric conversion portion 17 and is formed of a transparent or opaque conductive material such as ITO, aluminum, titanium nitride, or the like. The pixel electrode 12 collects charges generated in the photoelectric conversion layer 14 for each photoelectric conversion unit 17. The pixel electrode 12 of each photoelectric conversion unit 17 is electrically connected to the signal readout circuit unit 11 via a connection unit 7 made of a conductive material so as to penetrate the insulating layer 5.

  The counter electrode 16 is an electrode for applying a voltage to the photoelectric conversion layer 14 disposed between the pixel electrode 12 and generating an electric field in the photoelectric conversion layer 14. Since the counter electrode 16 is provided on the light incident surface side of the photoelectric conversion layer 14 and needs to be incident on the photoelectric conversion layer 14 through the counter electrode 16, the counter electrode 16 is transparent to the incident light. It is formed from a conductive material such as ITO.

  The photoelectric conversion layer 14 includes an organic photoelectric conversion film or an inorganic photoelectric conversion film that absorbs incident light and generates charges according to the absorbed light quantity. A function such as a charge blocking layer that suppresses the injection of charges from the electrode to the photoelectric conversion layer 14 between the photoelectric conversion layer 14 and the counter electrode 16 or between the photoelectric conversion layer 14 and the pixel electrode 12. A layer may be provided. The photoelectric conversion layer 14 is preferably a film common to all pixels. By making the photoelectric conversion layer 14 a film common to all the pixels, the aperture ratio can be set to 100% and high sensitivity can be obtained.

  FIG. 2 is a circuit diagram illustrating the signal readout circuit unit 11 in each pixel unit 20 and the relationship between the circuit unit 11 and the photoelectric conversion unit 17. As shown in FIG. 2, the signal readout circuit unit 11 includes an output transistor 32, a reset transistor 33, and a selection transistor 34. The output transistor 32, the reset transistor 33, and the selection transistor 34 are each composed of an n-channel MOS transistor. The photoelectric conversion unit 17 and the gate of the output transistor 32 are electrically connected, and this node is referred to as a floating diffusion FD (hereinafter simply referred to as FD). In FIG. 1, the signal readout circuit unit 11 is shown as one region, but in reality, the above-described elements are formed in this region.

  In the pixel unit 20 of the present embodiment, a bias voltage is applied to the pixel electrode 12 such that holes out of the charges generated in the photoelectric conversion layer 14 move to the pixel electrode 12 and electrons move to the counter electrode 16. Applied. The bias voltage is higher than the power supply voltage Vdd (voltage supplied to the drain of the output transistor in FIG. 2, for example, 3V) (5 V) as the bias voltage so that the photoelectric conversion layer 14 exhibits sufficiently high sensitivity. It is desirable to use about -20V, for example 10V).

  FD is a node including an n-type impurity region electrically connected to the pixel electrode 12. The FD has a capacitance due to the parasitic capacitance of the photoelectric conversion unit 17 and each transistor. Since the potential of the FD changes according to the amount of charges collected by the pixel electrode 12, the FD functions as a charge storage unit.

  The output transistor 32 converts the charge signal accumulated in the FD into a voltage signal and outputs it to the signal line. The gate terminal of the output transistor 32 is electrically connected to the FD, and the drain terminal is connected to the power supply voltage Vdd of the solid-state imaging device. The source terminal of the output transistor 32 is connected to the drain terminal of the selection transistor 34. The pixel unit 20 in the present embodiment is a circuit having a so-called three-transistor configuration in which the FD, the pixel electrode 12 of the photoelectric conversion unit 17, and the gate terminal of the output transistor 32 are electrically connected directly.

  The reset transistor 33 resets the potential of the FD to a reference potential. The FD is electrically connected to the drain terminal of the reset transistor 33, the reset power source is connected to the source terminal, and the voltage RD is supplied. When the reset pulse RS applied to the gate terminal of the reset transistor 33 becomes high level, the reset transistor 33 is turned on, and electrons are injected from the source to the drain of the reset transistor 33. Then, due to the injection of electrons, the potential of the FD drops and the potential of the FD is reset to the reference potential. The selection transistor 34 has a source terminal connected to the signal line, and selectively outputs a signal output from the output transistor 32 of each pixel to a signal line provided for each column. . When the selection pulse RW applied to the gate terminal of the selection transistor 34 becomes a high level, the selection transistor 34 is turned on, whereby a signal output from the output transistor 32 of each pixel is output to the signal line.

  In this embodiment, as schematically shown in the sectional view of FIG. 1, the light receiving area of the G pixel unit 20G is larger than the light receiving areas of the B pixel unit 20B and the R pixel unit 20R. The area (area in plan view) occupied by the lower signal readout circuit unit 11 on the substrate surface is substantially uniform. In the present invention, in one pixel portion 20, the area of the color filter and the photoelectric conversion portion in plan view does not necessarily match the size of the signal readout circuit portion. In the present invention, the area of each signal readout circuit section on the substrate surface is smaller than the area of the photoelectric conversion section having the largest area (in this example, the photoelectric conversion section of the G pixel section), and the photoelectric conversion having the smallest area. It is characterized by being larger than the area of the portion (in this example, the photoelectric conversion portion of the B and R pixel portions).

  3A and 3B show a specific color filter layout and a corresponding signal readout circuit portion layout. The position and size of the photoelectric conversion unit of each pixel coincides with the color filter.

  FIG. 3A shows a first layout 22a in which three color filters of an R (red) filter 21r, a G (green) filter 21g, and a B (blue) filter 21b are arranged in a 2 × 2 pattern, An example is shown in which the filters are arranged in a 4 × 4 period in which the second layout 22b having the same area as the first layout 22a but having a different 2 × 2 pattern arrangement is further arranged by 2 × 2. ing.

  As described above, when the color filter layer CF having the R, G, and B filters is provided, the area of the G filter 21r that transmits the wavelength having the highest visibility is maximized. In addition, when the partition for color mixing prevention etc. exists between color filters, the range to the centerline of the thickness of an adjacent partition shall be included in the area of one filter.

  In FIG. 3A, black frames shown in the filters 21r, 21g, and 21b indicate the outlines of the pixel electrodes 12r, 12g, and 12b of the photoelectric conversion unit corresponding to the filters. Signal charges are also generated in the gaps between adjacent pixel electrodes, and the generated signal charges are collected by the pixel electrodes 12, so that the area of each photoelectric conversion unit matches the area of each filter. That is, the area of the photoelectric conversion unit in which the G filter 21g is formed above is larger than the area of the photoelectric conversion unit in which the B filter 21b and the R filter 21r are formed above.

  In this example, the areas of the B filter 21b and the R filter 21r are the same, but the B filter and the R filter may be smaller than the G filter, and one may be larger than the other. In particular, it is preferable to set the area ratio of the R filter, the G filter, and the B filter based on the ratio of the contribution of each color signal to the luminance information in the conversion from the RGB color space to the YUV color space.

  G is a color with higher human visibility than R and B. By increasing the amount of light received by G, the S / N of the luminance signal (Y signal) can be improved. In particular, even when the pixel size is miniaturized, a decrease in the amount of received light G can be suppressed as compared with R and B, so that a decrease in the S / N of the luminance signal can be suppressed.

  FIG. 3B is a plan view schematically showing a formation region (rectangular portion indicated by oblique lines) of the signal readout circuit portion 11 disposed below FIG. 3A.

  Regardless of the size of the area of the color filter and the photoelectric conversion unit shown in FIG. 3A, as shown in FIG. 3B, the area of the signal readout circuit unit 11 in the plan view is almost uniform. It is larger than the area of the small filter (that is, the area of the smallest photoelectric conversion unit) and smaller than the area of the largest filter (that is, the area of the largest photoelectric conversion unit). Here, the area of the signal readout circuit portion 11 is defined as an area of a region surrounded by a center line (indicated by a two-dot chain line B in FIG. 3B) between the formation regions. Further, when a part of the signal readout circuit (impurity region, gate electrode, etc.) is shared by a plurality of adjacent pixels, the boundary region of each pixel is determined in consideration of each role. The area of the signal readout circuit unit arranged at the end of the many signal readout circuit units arranged two-dimensionally is at a position corresponding to the outer peripheral edge of the color filter arranged above the signal readout circuit unit. An imaginary rim is defined and is defined as an area surrounded by the rim and the center line.

  As described above, the signal readout circuit unit includes each element such as an FD, three transistors, and a capacitor, and the area of the signal readout circuit unit is a region where each element of one pixel portion is formed. The area is not necessarily the area of the rectangular area, and may be the area of a deformed polygon area or an area surrounded by a curve.

  In the present invention, since the photoelectric conversion unit and the signal readout circuit are formed on different surfaces, the area of the photoelectric conversion unit and the area of the signal readout circuit unit can be determined independently as described above. When the area of the signal readout circuit unit corresponding to the size of the filter and the photoelectric conversion unit is increased or decreased, the area of the signal readout circuit unit corresponding to the filter and the photoelectric conversion unit of a small area must be reduced. Circuit design and layout are very difficult. On the other hand, in the present invention, since the area of the signal readout circuit section is larger than the area of the smallest filter (that is, the area of the smallest photoelectric conversion section), the degree of design freedom can be improved. In addition, since it is desirable for the size of the entire device that the area of the entire photoelectric conversion unit and the area of the entire signal readout circuit unit are substantially equal, the area of each signal readout circuit unit is Make it smaller than the area of the largest filter. As in the case of the present embodiment, for example, it is preferable to arrange the patterns so that the area of the 2 × 2 filter is equal to the area of the 2 × 2 signal readout circuit section.

  4A and 4B show other specific color filter layouts and corresponding signal readout circuit portion layouts.

  In this example, a W (white) filter 21w is provided in addition to RGB. The W filter 21w transmits all the colors of R, G, and B. Even when compared with the same filter area, the received light amount of the photoelectric conversion unit can be made larger than when other filters are used. Effective for S / N improvement. Further, in the present invention, the luminance signal (Y signal) is obtained by making the area of the W filter 21w larger than the areas of the R, G, B filters 21r, 21g, 21b and increasing the amount of light received by the photoelectric conversion unit of the W pixel. ), And in particular, when the pixel size is miniaturized, the S / N drop of the luminance signal is suppressed. Each definition such as the area of the photoelectric conversion unit and the area of the filter conforms to the above embodiment (the same applies hereinafter).

  A larger W filter area is more effective for improving luminance S / N. However, if the area of each of the R, G, and B color filters becomes too small, the color S / N decreases conspicuously and the overall image quality deteriorates. Therefore, it is desirable to determine the size of each filter comprehensively including the pixel size and the like.

  FIG. 4B schematically shows an example of the layout of the signal readout circuit portion provided below the color filter shown in FIG. 4A. As shown in FIG. 4B, the areas of the signal readout circuit sections 11w, 11r, 11g, and 11b corresponding to each color (area surrounded by a two-dot chain line B) are uniform, and the 2 × 2 signal readout circuit section Is approximately the same as the area of the upper 2 × 2 filter.

  FIG. 4C schematically shows another example of the layout of the signal readout circuit portion provided below the color filter shown in FIG. 4A. As shown in FIG. 4C, for example, the areas of the signal readout circuit portions 11w and 11r corresponding to the W filter and the R filter are formed larger than the areas of the signal readout circuit portions 11b and 11g corresponding to the B filter and the G filter. It may be. The area of each signal readout circuit portion is the area of a region surrounded by a two-dot chain line B in the figure.

  Thus, the area of the signal readout circuit portion does not necessarily have to be uniform, and the area of the smallest signal readout circuit portion is larger than the area of the smallest color filter, and a region where the signal readout circuit portion can be sufficiently formed is formed. It only has to be ensured.

  As described above, the solid-state imaging device of the present invention is used when the area of the photoelectric conversion unit is miniaturized in a stacked type imaging device in which a photoelectric conversion unit including a photoelectric conversion layer is formed on a semiconductor circuit substrate. However, since the area of the signal readout circuit portion provided on the surface of the semiconductor substrate can be made larger than the area of the smallest photoelectric conversion portion, the degree of freedom in circuit design can be improved.

  FIG. 5 is a diagram illustrating an overall configuration of the solid-state imaging device 100 of the present embodiment. As shown in FIG. 5, the solid-state imaging device 100 of the present embodiment includes a vertical driver 121, a control unit 122, a signal processing circuit 123, a horizontal driver 124, an LVDS 125, a serial conversion unit 126, and a pad 127. And a pixel region (corresponding to an imaging unit) in which a plurality of pixel units 20 shown in FIG. 1 are arranged two-dimensionally. For the pixel region in FIG. 5, only the signal readout circuit unit 11 of the pixel unit 20 is schematically shown.

  The control unit 122 includes a timing generator and the like, outputs the frame synchronization signal VD and the row synchronization signal HD, and controls the operations of the vertical driver 121 and the horizontal driver 124 to control the charge signal in the pixel unit 20. It controls reading and the like.

  The vertical driver 121 outputs a reset pulse RS and a selection pulse RW to the signal readout circuit unit 11 based on the frame synchronization signal VD and the row synchronization signal HD output from the control unit 122, and the signal readout circuit unit 11 It controls the reset operation and the charge signal read operation.

  The signal processing circuit 123 is provided corresponding to each column of the signal readout circuit unit 11. The signal processing circuit 123 includes an ADC circuit that performs correlated double sampling (CDS) processing on the signals output from the corresponding columns and converts the processed signals into digital signals. The signal processed by the signal processing circuit 123 is stored in a memory provided for each column.

  The horizontal driver 124 performs control for sequentially reading out signals for one row of the pixel unit 20 stored in the memory of the signal processing circuit 123 and outputting the signals to the LVDS 125.

  The LVDS 125 transmits a digital signal in accordance with LVDS (low voltage differential signaling). The serial conversion unit 126 converts an input parallel digital signal into a serial signal and outputs it. The pad 127 is an interface used for input / output with the outside.

  In the description so far, the capacity of the charge storage portion of each pixel is not particularly limited. However, in the present invention, since a large amount of signal charge is generated in a pixel having a large photoelectric conversion unit, if the storage capacity is the same, the pixel is saturated with a smaller amount of light than the other pixels, and a sufficient dynamic range is obtained for the entire image sensor. May not be secured. For this reason, for a pixel having a large photoelectric conversion unit (G pixel of RGB array, W pixel of WRGB array), the capacity of the charge storage unit may be increased to ensure a sufficient number of saturated signal charges. For example, the capacity of the charge storage unit may be adjusted so that all pixels are saturated with substantially the same amount of light when a white subject is imaged.

  In the solid-state imaging device of the above-described embodiment, the configuration of the photoelectric conversion unit has been described as including the pixel electrode, the photoelectric conversion device, and the counter electrode. However, the two electrodes are arranged on the same plane (on the circuit board). A structure in which a photoelectric conversion film is provided between them may be provided.

  As a design change example, referring to FIGS. 6 to 9, a configuration including a photoelectric conversion unit having a configuration in which two electrodes are arranged on the same plane is provided. 6-9, the same code | symbol is attached | subjected to the element same as the component of the said embodiment.

  FIG. 6 is a diagram schematically showing a part of a cross section of the image sensor unit of the design change example, and FIG.

  In the present design change example, the photoelectric conversion unit 17 ′ has the surface of the insulating layer 5, that is, the surface of the insulating layer 5, that is, the pixel electrode 32 provided at the center in a plan view and the counter electrode 36 disposed so as to surround the pixel electrode 32. It differs from the above-described embodiment in that the photoelectric conversion layer 14 is provided on the same plane and formed on the pixel electrode 32 and the counter electrode 36.

The counter electrode 36 is formed in a mesh shape so as to surround each pixel electrode 32, is common to all the pixel electrodes, and is configured to be supplied with an appropriate voltage as in the case of the above embodiment. .
The pixel electrode 32 and the counter electrode 36 can be formed of the same material at the same time.

  In the case of this configuration, the center of the counter electrode indicated by the broken line C in FIGS. 6 and 7 is the boundary of the adjacent photoelectric conversion unit, and the area in plan view of one photoelectric conversion unit 17 ′ as shown in FIG. It is defined by a region surrounded by the center line C of the counter electrode.

  FIG. 8 is a plan view showing an example of a color filter layout corresponding to the layout of the photoelectric conversion unit shown in FIG. The position and size of the photoelectric conversion unit of each pixel coincides with the color filter. The layout shown in FIG. 8 is the same as that shown in FIG. 3A. In FIG. 8, the counter electrode 36 is also shown. As shown in FIG. 8, the center line of the counter electrode 36 and the color filter boundary coincide.

  FIG. 9 is a plan view schematically showing a formation region (rectangular portion indicated by oblique lines) of the signal readout circuit portion 11 arranged below FIG.

  In FIG. 9, as in FIG. 3B of the above-described embodiment, the area of the signal readout circuit portion 11 is the area of the region surrounded by the center line (indicated by a two-dot chain line D in FIG. 9) between the formation regions. is there. The definition of the area of the signal readout circuit section is the same as that in the above-described embodiment.

  As shown in FIG. 9, the size of the formation region of the signal readout circuit unit 11 is almost uniform regardless of the area of the color filter and the photoelectric conversion unit shown in FIG. The area of the readout circuit unit 11 is larger than the area of the smallest filter (that is, the area of the smallest photoelectric conversion unit) and smaller than the area of the largest filter (that is, the area of the largest photoelectric conversion unit).

  In this configuration as well, the area of the signal readout circuit section can be determined independently of the area of the photoelectric conversion section as in the above embodiment, and the degree of freedom in circuit design and layout is high.

  The solid-state imaging device of the above-described embodiment can be used for various imaging devices. Examples of the imaging device include a digital camera, a digital video camera, an electronic endoscope, and a camera-equipped mobile phone.

DESCRIPTION OF SYMBOLS 1 Semiconductor circuit board 11 Signal readout circuit 12 Pixel electrode 14 Photoelectric conversion layer 16 Counter electrode 17 Photoelectric conversion part 20 Pixel part 21 Color filter 22a First layout 22b of color filter Second layout 32 of color filter Output transistor 33 Reset transistor 34 selection transistor 100 solid-state image sensor FD floating diffusion CF color filter layer

Claims (9)

A plurality of photoelectric conversion units provided with a photoelectric conversion layer that generates a signal charge according to the amount of incident light, arranged two-dimensionally on the substrate,
A storage unit that is provided for each photoelectric conversion unit under the plurality of photoelectric conversion units on the substrate and accumulates charges generated in the photoelectric conversion units, and outputs a voltage corresponding to the signal charge of the storage unit. A signal readout circuit unit including an output circuit,
A color filter layer having color filters of different colors is disposed on the plurality of photoelectric conversion units so that the color filters correspond to the photoelectric conversion units in a ratio of 1: 1.
The area in plan view of the color filter and the photoelectric conversion unit corresponding to the color filter is determined for each color, and among the plurality of colors, the color filter of a predetermined color and the photoelectric conversion unit corresponding to the color filter Has the largest area,
A solid-state imaging device, wherein an area of each signal readout circuit unit is smaller than an area of the largest photoelectric conversion unit and larger than an area of the smallest photoelectric conversion unit.   2. The solid-state imaging device according to claim 1, wherein the predetermined color is a color having the highest visibility among the plurality of colors or having the largest contribution to the luminance S / N. The plurality of colors are red, green and blue;
The solid-state imaging device according to claim 2, wherein the predetermined color is green. The plurality of colors are white, red, green and blue;
The solid-state imaging device according to claim 2, wherein the predetermined color is white. The photoelectric conversion unit includes the photoelectric conversion layer, a pixel electrode partitioned in units of photoelectric conversion units, and a counter electrode provided to face the pixel electrode with the photoelectric conversion layer interposed therebetween,
5. The solid-state imaging device according to claim 1, wherein the counter electrode is a common electrode for all of the photoelectric conversion units.   The solid-state imaging device according to claim 1, wherein the photoelectric conversion layer is a film common to all the photoelectric conversion units.   The solid-state imaging device according to claim 1, wherein the photoelectric conversion layer includes an organic photoelectric conversion film.   The storage unit in the signal readout circuit unit provided for each of the photoelectric conversion units is capacity-adjusted so that the plurality of photoelectric conversion units are saturated with the same amount of light when a white light source is imaged. The solid-state imaging device according to claim 1, wherein   An image pickup apparatus comprising the solid-state image pickup device according to claim 1.

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