JP2009016432A - Solid image-capturing element and image-capturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid image-capturing element and an image-capturing device which can uniformly lower an applied voltage needed to sweep and dump accumulated charges of pixels in an entire photosensitive pixel area to an overflow drain, and can carry out precise black-level amendment. <P>SOLUTION: A semiconductor substrate has a photosensitive pixel area 55 in which a plurality of pixels 63 each having a photosensor 61 photoelectrically converting incident light are arranged in line and column directions, and an optical black area 53 in which incident light is cut off to detect a black signal level. A plurality of dummy pixels 65 are arranged annularly around the photosensitive pixel area 55 in adjacent thereto, each dummy pixel 65 having a conductive semiconductor region identical with a charge accumulating portion of the photosensor 61. The optical black area 53 is formed to encircle the dummy pixels 65, and includes pixels 67 having photosensors and pixels 69 not having photosensors. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device and an imaging apparatus having a photosensitive pixel area and an optical black area.

  Solid-state image sensors such as CCD (Charge Coupled Device) image sensors and CMOS (Complementary Metal Oxide Semiconductor) image sensors are widely used in portable electronic devices that record images such as digital cameras, digital video cameras, and mobile phones with cameras. Has been. As shown in the schematic plan view of FIG. 11, the solid-state imaging device includes a photosensitive pixel 1 that generates charges in response to light, a plurality of vertical charge transfer units 3 that transfer generated charges in a column direction, A horizontal charge transfer unit 5 that is connected to the column charge downstream side of the vertical charge transfer unit 3 and transfers charges transferred by the vertical charge transfer unit 3 in the row direction, and is disposed on the charge transfer direction end side of the horizontal charge transfer unit 5. And an output amplifier 7 for converting the signal charge transferred by the horizontal charge transfer unit 5 into a signal voltage and amplifying it. In order to set the black level, an optical black region 13 is disposed outside the photosensitive pixel region 9 and the light receiving portion is covered with a light shielding film 11 made of a metal having a high light shielding property such as tungsten.

The above-described optical black region is used for generating a black level reference signal (see, for example, Patent Document 1). In this case, both the photosensitive pixel region and the optical black region are assumed to have the same pixel structure. A technique is disclosed that solves the problem of black floating and black sinking by making the dark currents in the same one (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 9-261543 JP 2001-144280 A

By the way, as shown in the C1-C2 cross section of FIG. 11 in FIG. 12, in the solid-state imaging device, an element isolation layer 17 composed of a p-type semiconductor layer is formed at a predetermined interval above the P well layer 15 of the silicon substrate. On each element isolation layer 17, the vertical charge transfer unit 3 made of an n-type semiconductor layer is formed. An n ⁻ type semiconductor layer 19 is formed between adjacent element isolation layers 17, and a read gate 21 made of a p type semiconductor layer is formed adjacent to one side of the vertical charge transfer portion 3. An element isolation layer 23 made of a p-type semiconductor layer is formed adjacent to the other side of the vertical charge transfer portion 3. A gate insulating film 25 is formed above each of these layers, and a transfer electrode 27 is formed above each vertical charge transfer portion 3. Further, an interlayer insulating film 29 and a light shielding film 11 are formed so as to cover the gate insulating film 25 and the transfer electrode 27. An opening 31 is formed in a part of the light shielding film 11. A photodiode 37 composed of a p-type semiconductor layer 33 and an n ⁺ -type semiconductor layer 35 is formed in the photosensitive pixel 1 in the photosensitive pixel region 9 corresponding to the position of the opening 31. Such a photodiode does not exist in the light shielding pixel 39 in the optical black region 13.

  As described above, when the photodiode 37 is present in the photosensitive pixel 1 in the photosensitive pixel region 9 and the photodiode 37 is not present in the light-shielding pixel 39 in the optical black region 13, the conductivity type is different from that of the charge storage unit 35 of the photodiode 37. The element isolation layer 17 of the light-shielding pixel 39 formed in (1) has a higher majority carrier concentration. As a result, the charge separation effect of the element separation layer 17 around the photodiode 37 of the photosensitive pixel 1 adjacent to the light shielding pixel 39 is further strengthened. Along with this, the substrate voltage necessary for sweeping away the accumulated charge in the photodiode 37 of the pixel 1 to the overflow drain increases as compared with the pixel in which the photodiode 37 is formed in the adjacent pixel. In particular, when the pixel size is miniaturized, the distance between the pixels is shortened, so this phenomenon appears more prominently. A bright spot or line is formed on the outer edge side of the photosensitive pixel region 9 or in the photosensitive pixel region 9. The problem of appearing or skipping whites occurred.

  On the other hand, as described in Patent Document 2, when the photosensitive pixel region 9 and the optical black region 13 have the same pixel structure, the charge accumulated in the photodiode with respect to the pixel adjacent to the optical black region 13 is the same. Applied to the overflow drain can be made as low as the pixels in the other photosensitive pixel regions 9. However, in this configuration, a photodiode is formed in the entire optical black region, which has been considered as one of the factors that improve the manufacturing process. In addition, if there are many photodiodes in the optical black region, detection of the black level may be adversely affected. In particular, when there is a pixel to be imaged with an excessive amount of light, signal charge overflows from the photodiode 37 of the pixel. In some cases, the black level could not be accurately measured due to flowing into the photodiode in the adjacent optical black region.

  The present invention has been made in view of the above situation, and it is possible to equalize and lower the applied voltage necessary for sweeping out the accumulated charge of the entire pixel in the photosensitive pixel region to the overflow drain, and to accurately and appropriately An object of the present invention is to provide a solid-state imaging device and an imaging apparatus capable of performing black level correction.

The above object of the present invention is achieved by the following configuration.
(1) A photosensitive pixel region in which a plurality of pixels each provided with a photosensor that photoelectrically converts incident light is arranged in a row direction and a column direction, and an optical black region that blocks the incident light and detects a black signal level. A solid-state imaging device formed on a semiconductor substrate,
A plurality of dummy pixels are annularly arranged adjacent to the periphery of the photosensitive pixel region, and each of the dummy pixels has a semiconductor region of the same conductivity type as the charge storage portion of the photosensor,
The optical black region is disposed so as to surround the dummy pixel, and includes a pixel having the photosensor and a pixel not having the photosensor.

  According to this solid-state imaging device, a plurality of dummy pixels are annularly arranged adjacent to the entire periphery of the photosensitive pixel region, and each dummy pixel has a semiconductor region having the same conductivity type as the charge storage portion of the photosensor. Therefore, it is possible to prevent an increase in applied voltage necessary for sweeping out the accumulated charges of the entire pixels in the photosensitive pixel region to the overflow drain. Further, since the optical black region includes a pixel having a photosensor and a pixel not having a photosensor, for example, a pixel that does not have a photosensor under a condition where the brightness is high such that extra charge enters. The black level correction is performed using the detection signal from the pixel, and the switching control is performed such that the black level is corrected using the detection signal from the pixel having the photosensor under a low lightness condition where the dark current increases. It becomes possible.

(2) The solid-state imaging device according to (1), wherein a semiconductor region of the dummy pixel forms the photosensor.

  According to this solid-state imaging device, the dummy pixel can be easily formed because the semiconductor region of the dummy pixel and the photosensor have the same shape.

(3) The solid-state imaging device according to (1) or (2), wherein the dummy pixels are formed over at least a plurality of rows or a plurality of columns.

  According to this solid-state imaging device, by forming the dummy pixels over at least a plurality of rows or a plurality of columns, the substrate voltage necessary for sweeping unnecessary accumulated charges from the entire pixels in the photosensitive pixel region to the overflow drain is reduced. It is possible to prevent the increase, and the electric charge overflowing from the photosensitive pixel area at the time of blooming can be reliably dammed in the dummy pixel, and thereby the black level can be corrected accurately and appropriately in the optical black area.

(4) The solid-state imaging device according to any one of (1) to (3), wherein a photosensor formed in a pixel in the photosensitive pixel region has a charge storage unit including an n-type semiconductor layer. An element isolation layer formed between a pixel in the photosensitive pixel area and another pixel adjacent to the pixel is a p-type semiconductor layer, and the element isolation on the opposite side of the element isolation layer from the photosensor. A solid-state imaging device in which an n-type semiconductor layer is formed in the vicinity of the layer.

  According to this solid-state imaging device, the element isolation layer is made of a p-type semiconductor layer with respect to the charge storage portion made of the n-type semiconductor layer of the photosensor, and the n-type semiconductor layer is on the opposite side of the element isolation region from the photosensor. As a result, the potential of the charge barrier of the element isolation layer is lowered. As a result, the required applied voltage can be kept low when the unnecessary accumulated charge of the photosensor is swept away to the overflow drain.

(5) An output signal from the solid-state imaging device according to any one of (1) to (4) and a photosensitive pixel region of the solid-state imaging device is converted to a black level based on a detection signal from the optical black region. An image pickup apparatus comprising: a signal processing unit that performs correction and generates image data.

  According to this imaging apparatus, the substrate voltage necessary for sweeping away the accumulated charge in the entire photosensitive pixel region of the solid-state imaging device to the overflow drain is made uniform, and particularly the substrate voltage is kept low for the pixels at the outer edge of the photosensitive pixel region. Can do.

(6) In the imaging device according to (5), when the signal processing unit has high brightness of the image data based on brightness information of the captured image data, the photo sensor in the optical black region The black level is corrected using a detection signal from a pixel that does not have the light level, and when the brightness is low, the black level is corrected using a detection signal from a pixel having a photosensor in the optical black region. An imaging device having a switching function for performing.

  According to this imaging apparatus, under an imaging condition with high brightness that causes blooming, the brightness is such that the dark level is increased by correcting the black level using a detection signal from a pixel that does not have a photosensor. Under low conditions, the black level can be corrected using a detection signal from a pixel having a photosensor having the same structure as the photosensitive pixel region. Therefore, it is possible to correct the black level more accurately and appropriately.

  According to the present invention, the substrate voltage necessary for sweeping out the accumulated charges of the entire pixels in the photosensitive pixel region to the overflow drain can be made uniform and low, and the black level can be corrected accurately and appropriately. Can do.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a solid-state imaging device and an imaging device according to the invention will be described in detail with reference to the drawings.
FIG. 1 is a main part configuration diagram of a digital camera (imaging device) according to the present invention, and FIG. 2 is a schematic plan view conceptually showing a pixel arrangement of the solid-state imaging device shown in FIG.

(First embodiment)
As shown in FIG. 1, the digital camera 100 includes a CCD solid-state image sensor 41, a CPU 43 that performs overall control of the digital camera, an image sensor drive unit 45 that drives the solid-state image sensor 41 according to an instruction from the CPU 43, and a solid-state image sensor. Signal processing means 47 is provided for receiving a signal output from the image sensor 41, processing the signal, and outputting image data. The image sensor drive unit 45 outputs a readout pulse, a vertical transfer pulse φV, and a horizontal transfer pulse φH to the solid-state image sensor 41.

  A solid-state imaging device 41 schematically shown in FIG. 1 includes a plurality of photodiodes (not shown in FIG. 1), which are a large number of photosensors arranged in a two-dimensional array on the surface of a semiconductor substrate, and each photodiode. A plurality of columns of vertical charge transfer units (VCCDs) 49 formed on the sides of the columns are provided. A peripheral portion of the photosensitive pixel region 55 of the semiconductor substrate is a dummy pixel region 64 and an optical black (OB) region 53 covered with the light shielding film 51.

  Further, a horizontal charge transfer unit (HCCD) 57 is provided at the end of the charge transfer downstream type of each vertical charge transfer unit 49 to receive signal charges from the photodiodes transferred along the vertical charge transfer unit 49, respectively. The signal charge is transferred to the output terminal of the horizontal charge transfer unit 57. An output amplifier 59 is provided at the output end, and a voltage signal corresponding to the amount of signal charge is output to the signal processing unit 47.

  The signal processing unit 47 generates image data based on the signal charge in the photosensitive pixel area 55 and corrects the black level of the image data from the effective imaging area 55 using the data read from the optical black area 53, thereby correcting the image data. The later image data is output. The photosensor may be another photosensor such as a phototransistor in addition to a photodiode.

Here, a more detailed configuration of the solid-state imaging device 41 will be described with reference to FIG.
As shown in the schematic plan view of the solid-state imaging device in FIG. 2, the solid-state imaging device 41 includes a photosensitive pixel region 55 in which a plurality of pixels 63 each provided with a photodiode for photoelectrically converting incident light are arranged in the row direction and the column direction. A plurality of dummy pixels 65 arranged annularly adjacent to the periphery of the photosensitive pixel region 55, an optical black region 53 that surrounds the dummy pixels 65 and shields incident light and detects a black signal level. is doing.

  That is, a plurality of dummy pixels 65 are provided at positions adjacent to the outside of the photosensitive pixel region 55 with respect to the respective pixels 63 at the pixel position (upper and lower left and right ends in the drawing) of the photosensitive pixel region 55. . Therefore, on the outer side of the outer edges of the four sides of the photosensitive pixel region 55, one row of each row in the vertical direction and one column of dummy pixels 65 in the left and right directions are arranged. Dummy pixels 65 are also provided at the intersection positions of the rows and columns where the dummy pixels 65 are arranged.

  In addition, in the optical black region 53 disposed so as to surround the dummy pixel 65 further outside the annular dummy pixel 65, a pixel 67 having a photodiode and a pixel 69 having no photodiode are arranged. Provided. That is, a pixel 67 having a photodiode formed in a row outside one end side (the left end side in the drawing) of the dummy pixel region 64 is provided, and the other optical black region 53 surrounds the annular dummy pixel 65. Pixels 69 that do not have a plurality of photodiodes are arranged.

Next, a cross-sectional configuration of the planar structure solid-state imaging device will be described.
FIG. 3 is a cross-sectional view showing a cross section A1-A2-A3 of FIG.
In the solid-state imaging device 41 formed on the silicon substrate, an element isolation layer 73 made of a p-type semiconductor layer is formed at a predetermined interval above the P well layer 71 of the silicon substrate, and on the element isolation layer 73, A vertical charge transfer portion 49 made of an n-type semiconductor layer is formed. An n ⁻ type semiconductor layer 75 is formed between adjacent element isolation layers 73, and a read gate 77 made of a p type semiconductor layer is formed adjacent to one side of the vertical charge transfer portion 49. An element isolation layer 79 made of a p-type semiconductor layer is formed adjacent to the other side of the vertical charge transfer portion 49.

A gate insulating film 81 is formed above each of these layers, and a transfer electrode 83 is formed above each vertical charge transfer portion 49. Further, an interlayer insulating film 85 and a light shielding film 51 are formed so as to cover the gate insulating film 81 and the transfer electrode 83. An opening 87 is provided in a part of the light shielding film 51. A photodiode 61 composed of a p-type semiconductor layer 89 and an n ⁺ -type semiconductor layer 91 is formed in the photosensitive pixel 63 in the photosensitive pixel region 55 corresponding to the position of the opening 87. A photodiode 61 including a p-type semiconductor layer 93 and an n ⁺ -type semiconductor layer 95 having the same shape is also formed in the dummy pixel 65 in the dummy pixel region 64. However, the photodiode 61 of the dummy pixel 65 is not provided with a light detection function. Note that the pixel 97 adjacent to the dummy pixel 65 in the optical black region 53 shown in FIG. 3 is an n ⁻ type semiconductor layer 75 and does not have a photodiode.

The potential potential in the solid-state imaging device 10 having the cross-sectional structure is as follows.
FIG. 4 is a potential distribution diagram showing the potential potential at each position of the B1-B2 line shown in FIG.
The potential potential in the B1-B2 line indicated by the element isolation layer 73-photodiode 61-p well layer 71-substrate of the photosensitive pixel 63 that is the outer edge of the photosensitive pixel region 55 has a distribution indicated by a solid line in the drawing. That is, a potential barrier is formed in the element isolation layer 73, the readout gate 77, and the p-well layer 71, and a potential well is formed in the vertical charge transfer portion 49 and the photodiode 61.

Here, paying attention to the position of the p-well layer 71, when the photodiode 61 does not exist in the dummy pixel 65, the potential barrier of the p-well layer 71 is effectively formed high as shown by a one-dot chain line in the figure. The In this case, in order to sweep (reset) the accumulated charge of the photodiode 61 to the substrate which is the overflow drain, a potential of the substrate voltage Vsub3 is required as shown by a two-dot chain line in the figure. However, when a photodiode (substantially an N ⁺ type semiconductor layer) is present in the dummy pixel 65, the potential barrier of the p-well layer 71 is lowered as shown by the solid line in the figure, and as a result, the photodiode 61 The substrate voltage for resetting the accumulated charge is reduced from Vsub3 to Vsub2. As a result, it is usually necessary to apply the substrate voltage Vsub3 when resetting the accumulated charge of the entire photosensitive pixel region 55. However, according to the solid-state imaging device 41 of the present embodiment, the substrate voltage Vsub2 is applied. The entire region 55 including the pixel 63 at the outer edge of the photosensitive pixel region 55 can be reset.

That is, in the solid-state imaging device 41 of the present embodiment, a plurality of dummy pixels 65 are annularly arranged adjacent to the entire periphery of the photosensitive pixel region 55, and each dummy pixel 65 has a charge of the photodiode 61. Since the n ⁺ type semiconductor layer 95 having the same conductivity type as that of the storage portion is formed, the substrate voltage necessary for resetting the stored charge for the pixels 63 on the outer edge of the photosensitive pixel region 55 can be suppressed to a low level. Thereby, the substrate voltage at the time of resetting can be made uniform throughout the photosensitive pixel region 55 and kept low.

Further, according to the digital camera 100 equipped with the solid-state imaging device 41 having the above-described configuration, since the pixel 67 having the photodiode and the pixel 69 not having the photodiode are provided in the optical black region 53, the black The level correction can be optimally set according to the imaging conditions.
Specifically, the signal processing means 47 (see FIG. 1) of the digital camera 100 switches the shooting mode according to the shooting scene. For example, when there are a normal shooting mode under a sufficient amount of light and a night scene shooting mode with a small amount of light as the shooting mode, different black level correction processing is performed in each shooting mode.

  FIG. 5 shows a control flowchart at the time of photographing with the digital camera according to the present embodiment. As shown in FIG. 5, when shooting, first, a shooting mode is set by an appropriate camera operation unit (step S1), and shooting (exposure to the solid-state imaging device 41) is performed (step S2). ), The light and darkness of the captured image is determined by the signal processing means 47 (step S3). The determination of the brightness of the captured image may be “bright” when the shooting mode is the normal shooting mode, “dark” when the shooting mode is the night scene shooting mode, and further, referring to the luminance information of the actual captured image, The brightness level may be determined and set from the average brightness of the captured image, the brightness histogram, or the like.

  Then, the signal processing means 47 is a pixel that does not have a photodiode in the optical black region 53 (for example, on the Qb-Qb line shown in FIG. 2) under the occurrence of blooming or under the condition that the brightness is high enough to pass through the light shielding film. The black level is corrected using the detection signal from the pixel 69) (step S4). On the other hand, under the condition that the dark current accumulated in the photodiode is large and the brightness is low and cannot be ignored, the pixel from the pixel having the photodiode in the optical black region 53 (for example, the pixel 67 on the Qa-Qa line shown in FIG. 2). The black level is corrected using the detection signal (step S5). An image signal is output after such black level correction (step S6).

  As a result, the corrected image signal is corrected to a more appropriate black level, and the influence of dark current can be eliminated with high accuracy. Further, since a plurality of pixels 67 having photodiodes are arranged in the column direction (vertical direction in the figure) of the solid-state imaging device 41, when the black level changes along the column direction of the photosensitive pixel region 55. This can be corrected appropriately.

  As described above, according to the solid-state imaging device 41 and the digital camera 100 provided with the solid-state imaging device 41, the applied voltage required for sweeping the accumulated charges of the entire pixels 63 in the photosensitive pixel region 55 to the overflow drain is made uniform and low. In addition, more appropriate black level correction can be performed. Further, since the semiconductor region of the dummy pixel 65 and the photodiode 61 of the pixel 63 have the same shape, it can be formed together with the photodiode 61 of the photosensitive pixel region 55, and the manufacturing process of the solid-state imaging device 41 is complicated. There is nothing to do.

Various modifications can be considered for the solid-state imaging device 41 having the above-described configuration.
(Modification 1)
FIG. 6 shows a schematic plan view of Modification 1 of the solid-state imaging device.
The solid-state imaging device 41A of Modification 1 shown in FIG. 6 includes a pixel 67 having a photodiode by forming a column (Qa-Qa line) outside the column on one end side (left end side in the figure) of the dummy region 64. In addition, a pixel 67 having a photodiode is formed by forming a row (Pa-Pa line) outside the row on one end side (the lower end side in the figure) of the dummy region 64. A pixel 67 having a photodiode is also provided at the intersection of the row and column on one end side. A plurality of pixels 69 that do not have a photodiode are arranged so as to surround the annular dummy pixel 65 and the entire pixel 67 having the photodiode.

  In the case of the configuration of the first modification, when the brightness of the captured image is high, the pixel in the optical black region 53 does not have a photodiode (for example, the pixel 69 on the Qb-Qb line shown in FIG. 6 or the Pb-Pb line). The black level is corrected using the detection signal from the pixel 69). On the other hand, when the brightness is low, black is detected using a detection signal from a pixel having a photodiode in the optical black region 53 (for example, the pixel 67 on the Qa-Qa line or the pixel 67 on the Pa-Pa line shown in FIG. 6). Perform level correction.

  According to the solid-state image sensor 41A, a plurality of pixels 67 having photodiodes are arranged in the column direction (vertical direction) and the row direction (horizontal direction) of the solid-state image sensor 41. When the black level changes along the column direction, the row direction, or both directions, this can be corrected appropriately. Further, since the pixels 67 are provided only for the minimum required one column and one row, the black level can be corrected with high accuracy while improving the space efficiency.

(Modification 2)
FIG. 7 shows a schematic plan view of Modification 2 of the solid-state imaging device.
In the solid-state imaging device 41B of Modification 2 shown in FIG. 7, a pixel 67 having a photodiode is provided adjacent to each of the dummy pixels 65 arranged in a ring on the side opposite to the photosensitive pixel region 55. A pixel 67 having a photodiode is also provided at each intersection of the row and column of the pixel 67. That is, a plurality of pixels 67 having photodiodes are annularly arranged around the dummy pixels 65 in the optical black region 53 arranged outside the dummy pixels 65. A plurality of pixels 69 that do not have photodiodes are arranged so as to surround the entire pixel 67 arranged in a ring shape.

  According to this solid-state imaging device 41B, a plurality of pixels 67 having photodiodes are arranged in the column direction and the row direction over the entire circumference of the dummy pixel 65 arranged in a ring shape. When the black level changes in the direction, the row direction, or both directions, this can be corrected appropriately. In particular, when the photosensitive pixel region 55 has different black levels on the top, bottom, left and right, this can be corrected accurately, and highly accurate black level correction can be performed.

(Modifications 3 to 5)
Furthermore, the solid-state imaging device according to the present embodiment can be configured as the following modifications 3 to 5.
FIG. 8 is a schematic plan view of (a) Modification Example 3, (b) Modification Example 4, and (c) Modification Example 5 of the solid-state imaging device.
In Modification 3 shown in FIG. 8A, the pixels 67 having photodiodes are arranged at least one column apart from the dummy pixels 65. By separating the pixel 67 having the photodiode from the dummy pixel 65, when blooming or the like occurs in the photosensitive pixel region 55, the overflowing charge does not flow into the pixel 67, and the black level can be corrected stably. It becomes like this.

  In Modification 4 shown in FIG. 8B, a plurality of pixels 67 having the photodiodes shown in FIG. 8A are provided. In this case, since detection signals from many pixels can be used for black level correction, variations in detection values can be suppressed, and black level correction with higher accuracy can be achieved.

  In the fifth modification shown in FIG. 8C, a plurality of pixels 67 each having a photodiode are provided adjacent to the dummy pixel 65 in the column direction (vertical direction in the figure). Also in this case, black level correction can be performed satisfactorily as in the case where the pixels 67 are provided adjacent to each other in the row direction (horizontal direction in the figure). In particular, the black level is increased in the row direction of the photosensitive pixel region 55. This can be accurately corrected if it changes.

  As described above, the pixel having the photodiode and the pixel not having the photodiode can be arranged at arbitrary positions, respectively. Further, the number of pixels used for black level correction can be arbitrarily set as necessary. Furthermore, the pixel 67 having a photodiode may be arranged in a multiple ring shape such as double or triple instead of the single structure shown in FIG.

(Second Embodiment)
Next, a second embodiment will be described.
FIG. 9 is a cross-sectional view of the solid-state imaging device according to the second embodiment corresponding to A1-A2 shown in FIG. Here, the same parts as those in the structure shown in FIG.
In the solid-state imaging device 41 of the present embodiment, the n ⁺ type semiconductor layer 99 having the same conductivity type as the n type semiconductor layer 91 that is the charge storage portion of the photodiode 61 is provided on the dummy pixel 65 in the dummy pixel region 64. It is formed in a shape different from the case of forming 61. In other words, the photodiode 61 formed in the pixel 63 in the photosensitive pixel region 55 has the charge storage portion 91 made of an n-type semiconductor layer, and the pixel 63 in the photosensitive pixel region 55 and other pixels adjacent to the pixel 63. The element isolation layer 73 formed between the pixel (dummy pixel 65) is a p-type semiconductor layer, and an n-type semiconductor layer is provided in the vicinity of the element isolation layer 73 on the side opposite to the photodiode 61 of the element isolation layer 73. 99 is formed.

According to this solid-state imaging device, the device isolation layer 73 is made of a p-type semiconductor layer with respect to the charge storage portion 91 made of an n-type semiconductor layer of the photodiode 61, and on the opposite side of the device isolation region from the photodiode 61. By forming the n-type semiconductor layer, the potential barrier of the element isolation region is prevented from becoming high. As a result, the required substrate voltage can be kept low when performing a reset operation for sweeping away the accumulated charge of the photodiode 61 to the overflow drain. In addition, since the n ⁺ type semiconductor layer 99 is formed in the dummy pixel 65 only in a necessary area with a necessary size, the element structure can be simplified, and when a pixel having a photodiode adjacent to the dummy pixel 65 is formed, It is possible to more reliably prevent the charge that overflows when blooming occurs from flowing into the photosensitive pixel 63.
In addition, the same modification as the above-described first to fifth modifications can be made to the second embodiment.

(Third embodiment)
Next, a third embodiment will be described.
FIG. 10 is an explanatory diagram showing each pixel of the CMOS type solid-state imaging device and its wiring structure.
In the first and second embodiments described above, the CCD solid-state imaging device is applied. However, the present invention can also be applied to a CMOS solid-state imaging device shown in FIG.
A large number of pixels 103 are arranged in a square lattice pattern on the surface of the CMOS solid-state imaging device 41C, and R (red) and G (green) detected by each pixel 103 are formed at the bottom of each pixel 103. ), B (blue) signal readout circuit 105 for reading out image signals R, G, B corresponding to the signal charges is formed. In the present embodiment, the signal reading circuit 105 is a three-transistor signal reading circuit. Three signal readout circuits 105 are provided for each pixel. When each signal readout circuit 105 designates R, G, and B detection signals by the vertical shift register 107 and the horizontal shift register 109, an output signal is output. The data is read by the unit 111 and sent to the signal processing means 47 (see FIG. 1). Subsequent signal processing is similar to the procedure described above.

  As described above, the solid-state imaging device and the imaging device of the present invention can be used for various imaging devices such as a digital camera. In particular, the accumulated charge of the entire pixels in the photosensitive pixel region is swept to the overflow drain. The applied voltage required for discarding can be made uniform and low, and appropriate black level correction can be performed with high accuracy.

It is a principal part block diagram of the digital camera (imaging device) which concerns on this invention. FIG. 2 is a schematic plan view conceptually showing a pixel arrangement of the solid-state imaging device shown in FIG. 1. It is sectional drawing which shows the A1-A2-A3 cross section of FIG. FIG. 4 is a potential distribution diagram showing a potential potential at each position of the B1-B2 line shown in FIG. 3. It is a control flowchart at the time of imaging | photography with the digital camera which concerns on this embodiment. It is a plane schematic diagram of Modification 1 of the solid-state imaging device. It is a plane schematic diagram of Modification 2 of the solid-state imaging device. It is a plane schematic diagram of the modifications 3-5 of a solid-state image sensor. It is sectional drawing corresponding to A1-A2 shown in FIG. 2 of the solid-state image sensor which concerns on 2nd Embodiment. It is explanatory drawing which shows each pixel of a CMOS type solid-state image sensor, and its wiring structure. It is a plane schematic diagram of the conventional solid-state image sensor. It is C1-C2 sectional drawing shown in FIG.

Explanation of symbols

41, 41A, 41B, 41C Solid-state imaging device 45 Imaging device driving unit 47 Signal processing means 49 Vertical charge transfer unit (n-type semiconductor layer)
53 Optical black region 55 Photosensitive pixel region 61 Photodiode (photosensor)
63 pixels 65 dummy pixels 67 pixels having a photo sensor 69 pixels not having a photo sensor 81 element isolation layer 91 n ⁺ type semiconductor layer (charge storage portion)
95 n ⁺ type semiconductor layer (semiconductor region)
100 Digital camera (imaging device)

Claims (6)

A photosensitive pixel region in which a plurality of pixels each having a photosensor for photoelectrically converting incident light are arranged in a row direction and a column direction, and an optical black region for detecting a black signal level by blocking incident light, are provided on a semiconductor substrate. A solid-state imaging device formed,
A plurality of dummy pixels are annularly arranged adjacent to the periphery of the photosensitive pixel region, and each of the dummy pixels has a semiconductor region of the same conductivity type as the charge storage portion of the photosensor,
The optical black region is disposed so as to surround the dummy pixel, and includes a pixel having the photosensor and a pixel not having the photosensor. The solid-state imaging device according to claim 1,
A solid-state imaging device in which a semiconductor region of the dummy pixel forms the photosensor. The solid-state imaging device according to claim 1 or 2,
The dummy pixel is a solid-state imaging device formed over at least a plurality of rows or a plurality of columns. The solid-state imaging device according to any one of claims 1 to 3,
A photosensor formed in a pixel in the photosensitive pixel region has a charge storage portion made of an n-type semiconductor layer,
An element isolation layer formed between a pixel in the photosensitive pixel region and another pixel adjacent to the pixel is a p-type semiconductor layer,
A solid-state imaging device in which an n-type semiconductor layer is formed in the vicinity of the element isolation layer on the opposite side of the element isolation layer from the photosensor. The solid-state image sensor according to any one of claims 1 to 4,
A signal processing unit that corrects the black level of the output signal from the photosensitive pixel region of the solid-state imaging device based on the detection signal from the optical black region, and generates image data;
An imaging apparatus comprising: The imaging apparatus according to claim 5, wherein
When the signal processing means has a high brightness of the image data based on brightness information of the captured image data, the black level is detected using a detection signal from a pixel having no photosensor in the optical black region. And a switching function that corrects the black level using a detection signal from a pixel having a photosensor in the optical black region when the brightness is low.

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