JP2009054806A - Imaging element and imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for making the resolution of a layered-type imaging element improved. <P>SOLUTION: The imaging element 105 has a layered structure comprising a lamination of a plurality of photodetection portions for detecting light beams in different wavelength ranges. With a pixel array of a photodetective portion of a G layer 201 shifted as a first layer of the layered structure, pixel arrays of the photodetection portions of an R layer 202 and a B layer 203 as one or more of the other layers are disposed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging element and an imaging apparatus.

  In recent years, imaging devices such as digital video cameras using imaging elements such as CCD image sensors and CMOS image sensors have become widespread. Commonly used color image pickup devices of image pickup apparatuses include a single plate type and a multi-plate type.

  In the single plate method, color separation is performed using a color filter. Primary color filters that separate into red (hereinafter referred to as “R”), green (hereinafter referred to as “G”), and blue (hereinafter referred to as “B”), and complementary color filters that separate into cyan, yellow, magenta, and green are often used. used. Since this method absorbs light with a color filter, there is a disadvantage that the light utilization efficiency is deteriorated.

  In the multi-plate method, color separation is performed using a prism. Since all R, G, and B light is used, the light utilization efficiency is high. However, since high-precision prisms and color separation films are required, advanced alignment techniques are required. As a result, there arises a problem that the cost becomes high and the apparatus becomes large.

  In recent years, image sensors that solve both problems have been developed. This is a multi-layer image pickup device. A light receiving unit that detects light in a specific wavelength region is stacked, and color separation is performed in the depth direction. Since this image sensor performs color separation with light at the same position, color misregistration due to correction as in the single plate method does not occur. Further, since light is not absorbed unlike a color filter, the light use efficiency is high. In addition, since color separation is performed by a multilayer imaging device, the structure is not increased as in the multi-plate method.

  Patent Document 1 discloses a method in which an organic semiconductor light receiving portion and an inorganic semiconductor photosensitive layer on a Si substrate are used in combination. The first light receiving portion is made of an organic semiconductor, and the second and third light receiving portions are formed in the silicon substrate, and are configured to separate colors according to the depth of light penetration. The first light receiving unit is characterized in that it receives green light, improving the sensitivity of green and good color separation between blue and red.

Patent Document 2 discloses a multilayer image pickup element including a multilayer electromagnetic wave absorption / photoelectric conversion part, a charge transfer / charge reading part, and an inter-electrode contact part that connects these parts. This image sensor is characterized in that the distance between the outermost surfaces of the electrodes of the pixel unit is shorter than the pixel size. As a result, an image sensor that has high sensitivity and high resolution and does not generate shading even when the pixel density is high is realized.
JP 2003-332551 A JP 2005-268609 A

  However, Patent Document 1 calls for further improvement of color separation. Further, the thickness due to the combined use of the light receiving portion and the inorganic semiconductor photosensitive layer is a problem.

  Further, due to the recent demand for high-pixel cameras, the multilayer image sensor of Patent Document 2 is required to further improve resolution, improve S / N at the same resolution, and improve sensitivity.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to improve the resolution of a multilayer image sensor.

  A first aspect of the present invention relates to an imaging device, and includes a stacked structure in which a plurality of light receiving portions that detect light in different wavelength ranges are stacked, and the pixel array of the light receiving portions of the first layer of the stacked structure On the other hand, the pixel arrangement of the light receiving portions of the other one or more layers is shifted by a certain amount.

  According to a second aspect of the present invention, there is provided an imaging apparatus comprising: an imaging optical system; and the above-described imaging element that receives light that has passed through the imaging optical system.

  According to the present invention, the resolution of the multilayer image sensor can be improved.

(First embodiment)
FIG. 1 is a schematic configuration diagram of an imaging apparatus according to a preferred first embodiment of the present invention. The subject image that has passed through the lens 101 and the diaphragm 102 as the imaging optical system is photoelectrically converted into R, G, and B by the imaging element 103 and converted into an electrical signal. Here, the lens 101 may be configured to be removable. The image sensor 103 is driven by a pulse output from the TG 104. The converted electrical signal is A / D converted by the AFE 105 and sent to the camera signal processing circuit 106. The signal subjected to the signal processing by the camera signal processing circuit 106 is recorded as still image data for still images on a still image recording medium 107 constituted by, for example, a semiconductor storage device. After moving image data is processed by the video signal processing circuit 108, the moving image data passes through the display circuit 109 and is displayed on the display unit 110 such as an LCD or a viewfinder. In moving image shooting, the image is recorded on a moving image recording medium 111 such as a semiconductor memory or a recordable DVD disk. The CPU 112 functions as a control unit that controls each unit of the imaging apparatus, and can control various operations according to user operations, for example.

  FIG. 2 is a perspective view showing a pixel arrangement of each layer of the light receiving unit in the imaging device according to the preferred first embodiment of the present invention. FIG. 3 is a top view of FIG. 2, and schematically shows output positions of the respective colors of the image sensor according to the preferred first embodiment of the present invention. The image sensor 103 according to the present embodiment has a stacked structure in which a plurality of light receiving units that detect light in different wavelength ranges are stacked. Specifically, from the light source side, the first light receiving unit is a light receiving unit (G layer) 201 that detects the G wavelength range, and the second light receiving unit is a light receiving unit (B layer) 202 that detects the B wavelength range. The third light receiving unit is laminated with a light receiving unit (R layer) 203 that detects light in the R wavelength region. In addition, the pixel arrangement of the light receiving units of one or more other layers is arranged with a certain amount of deviation from the pixel arrangement of the light receiving units of the first layer of the stacked structure. Specifically, the pixel arrangement of the B layer 202 and the R layer 203 is shifted by a certain amount in the horizontal direction and the vertical direction with respect to the pixel arrangement of the G layer 201. In FIG. 2, the pixel arrangement of the B layer 202 and the R layer 203 is shifted from the pixel arrangement of the G layer 201 by ½ pitch in the horizontal direction and the vertical direction, respectively. In FIG. 2, the pixel arrangement of the R layer 203 and the B layer 202 with respect to four pixels of the G layer 201 is shown. The pixel arrangement of each color is expressed as shown in FIG. 3 on a plane. For example, an organic semiconductor material described in Patent Document 1 is preferably used as a material constituting each light receiving unit.

  FIG. 4 is a cross-sectional view of a multilayer stacked image sensor according to the preferred first embodiment of the present invention. The multi-layer image pickup device includes a photoelectric conversion unit, a charge transmission unit, and a contact unit that connects the photoelectric conversion unit and the charge transmission unit. The photoelectric conversion unit includes transparent electrode films 401 to 406, photoelectric conversion films 407 to 409, and transparent insulating films 410 and 411. The charge transfer unit includes a charge storage diode 412, a charge transfer path 413, and an insulating film 414. The charge transfer unit is composed of an electrode 415.

  As shown in FIG. 4, the R layer 203 and the B layer 202 are stacked with the pixel arrangement shifted by 1/2 pitch with respect to the G layer 201 on the light source side. . By using the stacked image sensor with the above-described configuration, the R and B pixels are spatially sampled between the G pixels, so that these video signals are mixed. The resolution of the luminance signal obtained in this way is high even with the same number of pixels.

  In the present embodiment, an example in which the pixels of the R layer and the B layer are shifted by ½ pitch in the horizontal direction and the vertical direction with respect to the G layer is shown, but the present invention is not limited to this. For example, only the R layer, only the B layer, or both the R layer and the R layer may be shifted. Further, only the horizontal direction or only the vertical direction may be shifted. Further, the amount of shift can be changed as appropriate.

(Second Embodiment)
The second embodiment aims to improve the sensitivity further than the first embodiment. The schematic configuration of this embodiment is the same as that of FIG.

  In this embodiment, a microlens is used to improve sensitivity. Normally, one microlens is arranged for one pixel. However, in this embodiment, since the pixel arrangement is shifted for each layer, if the microlens is focused on, for example, the center of the G layer, the B layer and the R layer are focused at a position off the center. . If a microlens having the same size as one pixel is used, the light for one pixel is condensed at the same position, so that the effect of shifting the pixel does not appear.

  Therefore, in the present embodiment, the microlens is arranged so that light is condensed in a region where the pixels overlap in two or more layers where the pixel arrangement is shifted. Then, there are several condensing points in one pixel, and the integrated value is an output of one pixel. Hereinafter, as in the first embodiment, an example in which the R pixel and the B pixel are shifted by 1/2 pitch in the horizontal direction and the vertical direction with respect to the G pixel will be described.

  FIG. 5 is a cross-sectional view of a multilayer stacked image sensor according to a preferred second embodiment of the present invention. FIG. 5 is obtained by adding a microlens 501 to the configuration shown in FIG. As shown in FIG. 5, the size of the micro lens 501 is half of the pixel pitch. In the present embodiment, since the pixels are shifted in the horizontal direction and the vertical direction, the horizontal length of the microlens 501 is ½ of the pixel pitch, and the vertical length of the microlens 501 is also 1 pixel pitch. / 2.

  FIG. 6 is a plan view showing the relationship between the arrangement of pixels and light collection according to the second preferred embodiment of the present invention. In FIG. 6, the R layer and the B layer 602 are shifted from the G layer 601 by ½ pitch in the horizontal direction and the vertical direction. A break of light collected by the microlens 501 is indicated by dotted lines 603 (a to j). As a result of focusing by the microlens 501, positions 604 (1 to 16) irradiated to the light receiving unit are as shown in FIG. For example, light in a region surrounded by a, b, f, and g on the dotted line 603 is collected at 1 at the position 604. The area of the light irradiated to the light receiving unit may be smaller than the region where the G layer 601 and the R layer and B layer 602 overlap. As shown in FIG. 6, the input of the pixel 605 of the G layer 601 is a region surrounded by b, d, g, i, and its output is obtained by integrating the condensing points 6, 7, 10, and 11. Value. The input of the pixel 606 of the R layer and the B layer is a region surrounded by a, c, h, and j, and the output thereof is a value obtained by integrating the condensing points 3, 4, 7, and 8.

  With the above-described configuration, even when pixel shifting is performed in the multilayer stacked image sensor, the light collection rate can be increased and the sensitivity can be increased using the microlens.

  Also in this embodiment, similarly to the first embodiment, only the R layer, only the B layer, or both the R layer and the B layer may be shifted. Further, only the horizontal direction or only the vertical direction may be shifted. Further, the amount of shift can be changed as appropriate.

1 is a schematic configuration diagram of an imaging apparatus according to a preferred first embodiment of the present invention. It is the perspective view which showed the pixel arrangement | sequence of each layer of the light-receiving part in the image pick-up element which concerns on suitable 1st Embodiment of this invention. FIG. 3 is a top view of FIG. 2, schematically showing output positions of respective colors of the image sensor according to the preferred first embodiment of the present invention. 1 is a cross-sectional view of a multilayer stacked image sensor according to a preferred first embodiment of the present invention. It is sectional drawing of the multilayer lamination type image pick-up element concerning the suitable 2nd Embodiment of this invention. It is a top view which shows the relationship between pixel arrangement | positioning and condensing based on suitable 2nd Embodiment of this invention.

Explanation of symbols

105 Image sensor 201 G layer (first layer)
202 R layer (one or more other layers)
203 B layer (one or more other layers)

Claims (5)

Provided with a laminated structure in which a plurality of light receiving parts for detecting light in different wavelength ranges are laminated,
An image pickup device, wherein a pixel arrangement of light receiving portions of one or more other layers is shifted by a certain amount with respect to a pixel arrangement of light receiving portions of the first layer of the stacked structure.   The image sensor according to claim 1, wherein the predetermined amount is ½ of a pixel pitch of a light receiving portion of the first layer.   The microlens further includes a microlens disposed so as to condense in a region where the pixel of the light receiving unit of the first layer and the pixel of the layer disposed with a certain amount of displacement from the first layer overlap. The imaging device according to claim 1.   The image sensor according to claim 3, wherein the size of the microlens is ½ of the pixel pitch of the light receiving portion of the first layer. An imaging optical system;
The imaging device according to any one of claims 1 to 4, which receives light that has passed through the imaging optical system;
An imaging apparatus comprising:

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