JP2006179696A - Solid-state imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To lower reading voltage without degrading vertical transfer characteristics and reduce a fluctuation in the reading voltage in a CCD-type solid-state imaging apparatus. <P>SOLUTION: A potential distribution having a partial impurity region 14 with a potential getting deeper in the charge transfer direction is formed under a transfer electrode 12 also serving to read among transfer electrodes of a vertical transfer register 15 constituting the solid-state imaging apparatus 1. The center of gravity of the reading region with a deep potential for reading a signal charge from a light receiving part under the transfer electrode 12 also serving to read is located approximately at the same position as the center of gravity of the light receiving part 6 in the charge transfer direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a solid-state imaging device, and more particularly to a solid-state imaging device using a charge coupled device (CCD).

A solid-state imaging device using a charge coupled device (CCD) is known as a solid-state imaging device.
This CCD type solid-state imaging device generates a signal charge corresponding to the amount of light received by a photoelectric conversion element, that is, a photodiode (PD), and a plurality of pixels by a light receiving unit to be accumulated are arranged in a two-dimensional matrix, The signal charges read based on the light signals of the subject incident on the light receiving portions of the plurality of pixels are transferred in the vertical direction by the vertical transfer registers arranged for the respective light receiving portion rows, and are horizontal by the horizontal transfer registers having the CCD structure. The image is transferred in the direction and output as image information of the subject from the output unit having the charge-voltage conversion unit.

Conventionally, various configurations have been proposed as a CCD type solid-state imaging device. Patent Document 1 proposes a CCD type solid-state imaging device that reduces the readout voltage when reading signal charges from a light receiving unit to a vertical transfer register. Has been.
6A and 6B show an outline of a CCD solid-state imaging device disclosed in Patent Document 1. FIG. The figure shows the main part of the imaging area.

  As shown in FIG. 6A, this CCD type solid-state imaging device 101 is arranged on one side for each of a plurality of light receiving sections 106 arranged in a two-dimensional matrix and each vertical row of the plurality of light receiving sections, and the light receiving section. A vertical transfer register 115 having a CCD structure having a transfer channel 108 for vertically transferring the signal charge generated in the unit in the direction of arrow c, and receiving the signal charge from the vertical transfer register 115 and transferring the signal charge in the horizontal direction. And a horizontal transfer register (not shown) and an output unit (not shown) having a charge-voltage conversion unit. The plurality of light receiving units 106 and the plurality of vertical transfer registers 115 form an imaging region. Further, a unit pixel is constituted by one light receiving unit 106 and a portion of the vertical transfer register 115 corresponding to the light receiving unit 106.

The vertical transfer register 115 is formed by, for example, a buried transfer channel 108 and a plurality of transfer electrodes 112 and 113 arranged along the charge transfer direction c via an insulating film. Since the vertical transfer register 115 is driven by four-phase vertical drive pulses φV _{1 to} φV ₄ , two transfer electrodes for one light receiving unit 106, that is, the first transfer electrode 112 also serving as signal charge reading, A second transfer electrode 113 that does not contribute to reading is formed correspondingly. In this case, the first transfer electrode 112 that also serves as a read-out is arranged on the downstream side with respect to the charge transfer direction, and is formed so that the electrode length L ₁ is larger than the electrode length L _{2 of} the second transfer electrode 113. The

  FIG. 6B shows a cross-sectional structure of the unit pixel. In this example, a first well region 103 of a second conductivity type, for example, p-type, is formed on a substrate 102 of a first conductivity type, for example, n-type silicon (Si), and an n well is formed on the upper surface of the first well region 103. A light-receiving portion 106 is formed by a photodiode in which a p + accumulation layer 105 for suppressing the dark semiconductor layer 104 and the dark current is sequentially formed. Further, a pixel adjacent to a read channel 107 constituting a later-described read gate portion and an n-type transfer channel 108 constituting a later-described vertical transfer portion, which are formed by leaving the first well region with a predetermined width. And a p + channel stop region 109 is provided. A p-type second well region 110 is provided below the n-type transfer channel 108.

An insulating film 111 is deposited on the surface extending from the read channel 107 to the channel stop region 109, and the first and second transfer electrodes 112 and 113 having a two-layer structure made of polycrystalline silicon are formed on the insulating film 111. Is formed.
The transfer channel 108, the insulating film 111, and the first and second transfer electrodes 112 and 113 form a vertical transfer register 115 having a CCD structure. Further, the first transfer electrode 112 is extended on the read channel 107 between the vertical transfer register 115 and the light receiving unit 106, and the read gate unit 117 is formed here. In other words, the first transfer electrode 112 also serves as an electrode that contributes to readout of signal charges, that is, a readout electrode. The second transfer electrode 113 does not contribute to reading signal charges.

As shown in FIGS. 6A and 6B, the first and second transfer electrodes 112 and 113 are formed so as to define an opening through which the light receiving portion 106 is exposed by a photodiode.
Although not shown, an interlayer insulating film and a light shielding film are formed on the entire surface of the first and second transfer electrodes 112 and 113 along the shape of the first and second transfer electrodes 112. The film is extended as necessary to the side surface of the first transfer electrode 112, that is, to the peripheral portion of the light receiving unit 106, thereby suppressing light incidence to other than the light receiving unit 106.

In the solid-state imaging device 101 with this configuration, the light receiving unit 106 accumulates signal charges generated by photoelectric conversion of incident light, and applies a read voltage to the first transfer electrode 112 by applying a read voltage to the first transfer electrodes 112. Reading is performed to the transfer channel 108 under the first transfer electrode 112 of the vertical transfer register 115 through the read gate unit 117.
The signal charges read to the vertical transfer register 115 are converted into vertical directions indicated by arrows in FIG. 6A by four-phase vertical drive pulse voltages φV _{1 to} φV ₄ applied to the first and second transfer electrodes 112 and 113. Are vertically transferred to a horizontal transfer unit (not shown).

In the solid-state imaging device 101, the ratio of the transfer direction of the contributing to the readout of the signal charge 1 of transfer electrodes 112 a length L _1, the transfer direction of the second transfer electrode 113 which does not contribute to readout the length L ₂ Thus, the read voltage is reduced by using a large configuration.
Japanese Patent Laid-Open No. 9-326483

However, in the solid-state imaging device 101 having such a configuration, although the readout voltage can be reduced, the difference between the lengths L ₁ and L ₂ in the vertical direction of the first transfer electrode 112 and the second transfer electrode 113 is not affected. Based on this, the vertical transfer characteristic when the signal charge is transferred in the vertical direction is deteriorated.

  FIG. 7 shows a CCD type solid-state imaging device in which the vertical transfer deterioration is improved. In this CCD type solid-state imaging device 121, a p-type impurity region 114 is formed on a part of the n-type transfer channel 108 immediately below the first transfer electrode 112, that is, on the upstream side in the charge transfer direction, and the potential 122 in the vertical transfer direction. The gradient is formed. In this example, the first and second transfer electrodes 112 and 113 are formed with a single layer structure of a polycrystalline silicon film. Since other configurations are the same as those in FIG. 6, corresponding portions are denoted by the same reference numerals, and redundant description is omitted.

  The vertical transfer deterioration can be suppressed by selectively forming a p-type impurity region 114 in a part of the n-type transfer channel 108 and forming a potential gradient in the vertical transfer direction. However, by forming this impurity region 114, as shown in FIG. 7A, the signal charge is read out from the light receiving portion 106, and the region corresponding to the deepest potential portion immediately below the first transfer electrode 112 where it is substantially accumulated ( Hereinafter, the position of the center of gravity Y ′ of 116 (referred to as a readout region) is shifted from the position of the center of gravity X ′ of the light receiving unit 106 in the vertical direction. For this reason, the distance between the center of gravity X ′ and the center of gravity Y ′, that is, the readout path during readout becomes long.

  Such an increase in the length of the read path, that is, the read path is not preferable because it causes an increase in the read voltage. Therefore, in the CCD solid-state imaging device of FIG. 7, it has been difficult to sufficiently reduce the readout voltage, that is, to sufficiently reduce the power consumption, although the vertical transfer efficiency is improved.

  In view of the above, the present invention provides a solid-state imaging device, that is, a CCD type solid-state imaging device that can reduce a read voltage without changing the transfer efficiency of a vertical transfer register.

  The solid-state imaging device according to the present invention includes a plurality of light receiving units regularly arranged and a vertical transfer register corresponding to each light receiving unit column, and of the transfer electrodes of the vertical transfer register, the transfer electrode also serving as a read-out Below, a potential distribution is formed so as to have a partial impurity region and the potential deepens in the charge transfer direction, and has a deep potential for reading signal charges from the light receiving portion under the transfer electrode that also serves as the readout. The center of gravity of the readout region is substantially at the same position as the center of gravity of the light receiving unit with respect to the charge transfer direction.

In the solid-state imaging device according to the present invention, the transfer electrode that also serves as the readout is formed with a length in the charge transfer direction larger than that of the other transfer electrodes.
Further, in the solid-state imaging device according to the present invention, two transfer electrodes, that is, a transfer electrode also serving as the readout and another transfer electrode are disposed corresponding to each of the light receiving portions, and the transfer electrode also serving as the readout is a charge It is arranged on the upstream side in the transfer direction.
In the solid-state imaging device according to the aspect of the invention, the impurity region may be formed in a shape that gradually separates from the light receiving portion in the charge transfer direction.

  According to the solid-state imaging device according to the present invention, the potential distribution is such that, among the transfer electrodes of the vertical transfer register, there is a partial impurity region below the transfer electrode that also serves as readout, and the potential becomes deeper in the charge transfer direction. The vertical transfer efficiency of the signal charge can be improved by forming. In addition, since the center of gravity of the readout region having a deep potential from which the signal charge is read out from the light receiving unit under the transfer electrode also serving as readout is substantially equal to the center of gravity of the light receiving unit with respect to the charge transfer direction, The distance between the centroid of the readout region and the centroid of the light receiving unit is shortened, and the readout voltage can be reduced. Since the read voltage does not depend on the impurity concentration of the impurity region and can be controlled only by the impurity concentration under the read gate portion, variations in the read voltage are reduced. Therefore, it is possible to provide a solid-state imaging device capable of reducing the read voltage and, in turn, reducing the power consumption without changing the vertical transfer efficiency of the signal charge.

The transfer electrode that also serves as a read is formed to have a larger length in the charge transfer direction than the other transfer electrodes, so that the read gap from the light receiving portion to the read region can be widened, and the read voltage is reduced. be able to.
Corresponding to each light receiving portion, two transfer electrodes, ie, a transfer electrode that also serves as a readout and another transfer electrode, are arranged, and the transfer electrode that also serves as a readout is arranged on the upstream side in the charge transfer direction. Can be set to a position substantially equal to the center of gravity of the light receiving unit in the vertical direction.
The impurity region under the transfer electrode that also serves as a readout is formed in a shape that gradually moves away from the light receiving portion in the charge transfer direction, so that the reading opening from the light receiving portion to the reading region can be further widened, The read voltage can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to these embodiments.

1 and 2 show a first embodiment of a solid-state imaging device according to the present invention, that is, a CCD type solid-state imaging device.
As shown in FIG. 1, the CCD solid-state imaging device 1 according to the present embodiment has a plurality of light receiving elements that are regularly arranged, for example, photoelectric conversion elements arranged in a two-dimensional matrix, in this case, photodiodes. Vertical transfer of a CCD structure having a transfer channel 8 arranged on one side for each vertical column of the light receiving portions 6 and the signal charges generated by the light receiving portions 6 in the direction of arrow c. A register 15, a horizontal transfer register (not shown) having a CCD structure for receiving and transferring signal charges from the vertical transfer register 15, and an output unit (not shown) having a charge-voltage conversion unit; Composed.
Here, an imaging region is formed by the plurality of light receiving units 6 and the plurality of vertical transfer registers 15. A unit pixel is formed by one light receiving unit 6 and a portion of the vertical transfer register 15 corresponding to the light receiving unit 6.

The vertical transfer register 15 is formed by, for example, a buried transfer channel 8 and a plurality of transfer electrodes 12 and 13 arranged along the charge transfer direction c via an insulating film. Since the vertical transfer register 15 of this example is driven by four-phase vertical drive pulses φV _{1 to} φV ₄ , two transfer electrodes for one light receiving unit 6, that is, a first transfer that also serves to read a signal charge. The electrode 12 and the second transfer electrode 13 that does not contribute to reading are formed correspondingly.

In the present embodiment, in particular, the first transfer electrode 12 that also serves as a read is disposed on the upstream side in the charge transfer direction from the second transfer electrode 13 that does not contribute to the read, and the first transfer electrode 12 The substantial electrode length L ₁ is set larger than the substantial electrode length L ₂ of the second transfer electrode 13 (L ₁ > L ₂ ). In addition, an impurity region 14 having a conductivity type opposite to the conductivity type of the transfer channel 8 is formed in a part of the transfer channel 8 below the first transfer electrode 12 on the upstream side in the charge transfer direction c. 12 is formed so as to form a potential distribution that deepens the potential in the charge transfer direction c, in this example, a stepped potential 21 (see FIG. 2B).

  In this manner, in the present embodiment, signal charges are read from the light receiving portion 6 below the first transfer electrode 12 that also serves as a readout, and the center of gravity Y of the readout region 16 having a deep potential accumulated is the charge transfer direction. With respect to c, the light receiving unit 6 is configured to be substantially equal to the center of gravity X. In other words, it is desirable that the center of gravity X of the light receiving unit 6 and the center of gravity Y of the readout region 14 below the first transfer electrode 12 are in the same position with respect to the charge transfer direction c, but the readout voltage is not affected. In addition, the positions of the center of gravity X and the center of gravity Y may be slightly shifted with respect to the charge transfer direction c.

  The first and second transfer electrodes 12 and 13 are formed with a single layer structure of, for example, polycrystalline silicon. The corresponding first transfer electrodes 12 of each vertical transfer register 15 are connected to each other in the horizontal direction between the light receiving portions 6 adjacent to each other in the vertical direction. The entire layout is formed in an upward concave shape so that the transfer electrodes 13 are connected for each horizontal line between the light receiving portions 6 adjacent in the vertical direction. The impurity region 14 is formed in a quadrangular shape when viewed from above.

2A and 2B show the cross-sectional structure of the unit pixel of FIG. In the present embodiment, a first well region 3 of the second conductivity type, for example, p-type is formed on the semiconductor substrate 2 of the first conductivity type, for example, n-type silicon (Si), and the upper surface of the first well region 3 is formed. In addition, a light receiving portion 6 is formed by a photodiode (so-called HAD sensor: Hole Accumulation Diode sensor) which becomes a photoelectric conversion element in which an n-type semiconductor layer 4 and a p + accumulation layer 5 for suppressing dark current are sequentially formed. Is done.
Further, the first well region is left with a predetermined width, and the read channel 7 constituting the read gate portion 17 and the buried n-type transfer channel 8 constituting the vertical transfer portion 15 are adjacent to each other. A partitioning p + channel stop region 9 is provided. A p-type second well region 10 is provided below the n-type transfer channel 8.

In addition, an insulating film 11 is formed on the surface extending over the light receiving portion 6, the readout channel 7, the transfer channel 8, and the channel stop region 9, and a single layer structure of, for example, polycrystalline silicon is formed on the insulating film 11. First and second transfer electrodes 12 and 13 are formed.
The transfer channel 8, the insulating film 11, and the first and second transfer electrodes 12 and 13 form a vertical transfer register 15 having a CCD structure. Further, the first transfer electrode 12 is extended on the readout channel 7 between the vertical transfer register 15 and the light receiving unit 6, and the readout base unit 17 is formed here. That is, the first transfer electrode 12 also serves as an electrode that contributes to readout of signal charges, that is, a readout electrode. The second transfer electrode 13 does not contribute to signal readout.

As shown in FIGS. 1, 2 </ b> A, and 2 </ b> B, the first and second transfer electrodes 12 and 13 are formed so as to define an opening through which the light receiving portion 6 is exposed by a photodiode. Although not shown, an interlayer insulating film and a light shielding film are formed on the entire surface of the first and second transfer electrodes 12 and 13 along the shape of the first and second transfer electrodes 12 and 13. These films are extended as necessary to the side surface of the first transfer electrode 12, that is, to the peripheral edge of the light receiving unit 6, so that light is directly incident on, for example, the transfer channel 8 other than the light receiving unit 6. Is suppressed.
On the other hand, as shown in FIG. 2B, the n-type transfer channel 8 includes a p-type impurity region 14 formed by ion implantation, for example, in a part of the region below the first transfer electrode 12 on the upstream side in the charge transfer direction c. And a stepped potential distribution 21 is formed under the first transfer electrode 12.

The operation of the CCD solid-state imaging device 1 according to the present embodiment will be described.
Based on the light incident on the light receiving unit 6, signal charges generated by photoelectric conversion are accumulated in the light receiving unit 6. The signal charge is read out to the transfer channel 8 below the first transfer electrode 12 in the vertical transfer register 15 through the read gate unit 17 when a read voltage is applied to the first transfer electrode 12.

  At this time, since the potential barrier is formed by the impurity region in the transfer channel 8, the signal charge from the light receiving unit 6 is read out to the deep readout region 16 under the first transfer electrode 12. Since the center of gravity Y of the readout region 16 is located substantially beside the center of gravity X of the light receiving unit 6, the readout path between the light receiving unit 6 and the readout region is substantially shortened, and readout can be performed with a low readout voltage. . FIG. 2C shows a schematic potential distribution 22 of the vertical transfer register 15 at the time of reading, and the signal charge e is read to the reading region 16 corresponding to the deepest part of the potential of the first transfer electrode 12.

The signal charges read to the vertical transfer register 15 are then directed to the horizontal transfer register unit by four-phase vertical drive pulses φV _{1 to} φV ₄ applied to the first transfer electrode 12 and the second transfer electrode 13. Are transferred vertically. In the vertical transfer in the vertical transfer register 15, since the first transfer electrodes 12 stepped potential 21 down with long electrode length L ₁ is formed, the signal charges are efficiently transferred. Then, it is sequentially output as image information from the output unit.

  According to the above-described CCD type solid-state imaging device 1 according to the present embodiment, the position of the impurity region 14 in the vertical direction can be adjusted without impairing the relative positional relationship with the first and second transfer electrodes 12 and 13. Since the center of gravity X of the readout region 16 can be set to a position substantially equal to the center of gravity X of the light receiving unit in the vertical direction. For this reason, compared with the conventional configuration, the read path, that is, the read path, can be shortened and the read voltage can be reduced. At the same time, by having the impurity region 14, the transfer efficiency of the signal charge in the vertical transfer register 15 can be increased. Further, since the read path does not pass through the vicinity of the first impurity region, the read voltage does not depend on the impurity concentration of the impurity region 14, can be controlled only by the impurity concentration under the read gate portion 17, and the variation in the read voltage is small. Become.

Next, a second embodiment of the CCD solid-state imaging device according to the present invention will be described with reference to FIG.
In the CCD type solid-state imaging device 23 according to the present embodiment, the impurity region 14 is not necessarily formed in a rectangular shape, but is formed in a trapezoidal shape or a triangular shape, in this example, a trapezoidal shape, and a readout region on the downstream side of the impurity region 14. The positions of the center of gravity Y of 16 and the center of gravity X of the light receiving unit 6 are configured to be substantially the same in the charge transfer direction. The trapezoidal impurity region 14 has a triangular portion that gradually moves away from the light receiving portion 6 in the charge transfer direction c.

Note that the boundary between the readout region 16 and the first impurity region 14 is the length of the first transfer electrode in the vertical direction (a in the figure) and the width of the impurity region in order to avoid deterioration of vertical transfer characteristics. A configuration including the center of a plane defined by (b in the figure) is preferable. In addition, if the boundary between the readout region 16 and the first impurity region 14 is formed with an extremely acute angle with the vertical transfer direction (arrow in the figure), the manufacturing margin becomes extremely severe. Therefore, the angle formed between the vertical transfer direction and the vertical transfer direction is preferably about 45 °, for example.
In FIG. 3, since the other structure is the same as that described in FIGS. 1 and 2, the same reference numerals are given to the corresponding parts, and the duplicate description is omitted.

According to the CCD type solid-state imaging device 23 according to the second embodiment, the signal charge transfer efficiency in the vertical transfer register 15 can be increased and the read voltage can be reduced as in the first embodiment. . In addition, variations in read voltage can be reduced.
When the length of the readout region 16 in the vertical direction is maximized on the side facing the corresponding light receiving unit 6, the signal charge readout voltage generated by the light receiving unit 6 is further reduced.

Next, a third embodiment of the CCD type solid-state imaging device according to the present invention will be described with reference to FIGS.
In the CCD solid-state imaging device 24 according to the present embodiment, the p-type impurity region 14 provided in the n-type transfer channel 8 under the first transfer electrode 12 that constitutes the vertical transfer register 15 is used as the first impurity having a high concentration. The region 25 and the second impurity region 26 having a lower concentration than the first impurity region 25 are in contact with the region 25, and a stepwise potential distribution 27 is formed so that the potential becomes deeper in the charge transfer direction. Configured as follows. Also in this case, the signal charges are read out, and the positions of the gravity center Y of the readout region 16 corresponding to the deepest part of the accumulated potential and the gravity center X of the light receiving unit 6 are substantially the same position with respect to the charge transfer direction c. Configured as follows. Since the other configuration is the same as that described with reference to FIG. 1, portions corresponding to those in FIG.
FIG. 5B is a schematic potential distribution at the time of reading, and the signal charge e is read to the reading region 16 corresponding to the deepest part of the potential.

  According to the CCD type solid-state imaging device 24 according to the third embodiment, the first and second impurity regions 25 and 26 are provided corresponding to each unit pixel in this order in the vertical transfer direction c. In other words, the stepwise potential distribution 27 is formed by changing the impurity concentration in the vertical transfer direction, thereby further improving the vertical transfer characteristics of the signal charge. Also in this embodiment, since the center of gravity Y of the readout region 16 is substantially right next to the center of gravity X of the light receiving unit 6, the readout voltage can be reduced. In addition, since the read path is formed away from the first and second impurity regions 25 and 26, that is, without being affected by these impurity regions, variations in the read voltage are reduced.

Although the embodiment of the solid-state imaging device according to the present invention has been described above, the solid-state imaging device according to the present invention is not limited to this embodiment.
For example, the electrode configuration is not necessarily limited to two electrodes, and the shape of the first transfer electrode does not have to be concave, and the structure can be either a single layer or a multilayer.
In addition, the solid-state imaging device according to the present invention can be applied to an interline transfer (IT) type or frame interline transfer (FIT) type solid-state imaging device.

In addition, for example, the impurity region formed in the transfer channel region may not be strictly trapezoidal or triangular, as long as it is maximized on the side facing the corresponding light receiving portion, and the impurity concentration also varies. The configuration is not limited to two stages, and a configuration in which changes are made continuously is also possible.
Further, when the balance between the transfer capability of the solid-state imaging device is important for the impurity region and the readout region, it is preferable to divide the transfer electrodes at equal intervals by making the areas substantially equal, but this is not necessarily limited thereto. The solid-state imaging device according to the present invention can be variously changed and modified.

1 is a schematic top view showing a configuration of a first embodiment of a solid-state imaging device according to the present invention. A, B, and C are a cross-sectional view taken along the line AA in FIG. 1, a cross-sectional view taken along the line BB, and a potential distribution diagram at the time of reading. It is a schematic top view which shows the structure of 2nd Embodiment of the solid-state imaging device which concerns on this invention. It is a schematic top view which shows the structure of 3rd Embodiment of the solid-state imaging device concerning this invention. FIGS. 5A and 5B are a cross-sectional view taken along line BB in FIG. 4 and a potential distribution diagram at the time of reading. A and B are a schematic top view and a schematic cross-sectional view showing a configuration of a conventional solid-state imaging device. A and B are a schematic top view and a schematic cross-sectional view showing a configuration of a conventional solid-state imaging device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Solid-state imaging device, 2 ... Board | substrate, 3 ... 1st well area | region, 4 ... n-type semiconductor layer, 5 ... Accumulation layer, 6 ... Light-receiving part, 7 * ..Gate portion, 8... N-type transfer channel, 9... Channel stop region, 10... Second well region, 11. ..Second transfer electrode, 14 ... impurity region (first impurity region), 15 ... vertical transfer register, 16 ... reading region, 17 ... reading gate portion, 21 ... potential , 22 ... potential, 23 ... solid-state imaging device, 24 ... solid-state imaging device, 25 ... first impurity region, 26 ... second impurity region, 27 ... potential, 28 ... potential, 101 ... conventional solid-state imaging device, 102 ... Plate 103 ... First well region 104 ... n-type semiconductor layer 105 ... Accumulation layer 106 ... Light receiving portion 107 ... Gate portion 108 ... n-type transfer Channel 109 109 Channel stop region 110 Second well region 111 Insulating film 112 First transfer electrode 113 Second transfer electrode 114 Impurity region, 115... Vertical transfer register, 116... Readout region, 117... Readout gate unit, 121.

Claims (4)

A plurality of light receiving units regularly arranged, and a vertical transfer register corresponding to each light receiving unit row,
Among the transfer electrodes of the vertical transfer register, a potential distribution is formed under the transfer electrode that also serves as a readout so that the potential becomes deeper in the charge transfer direction with a partial impurity region,
A solid center characterized in that the center of gravity of a readout region having a deep potential for reading out signal charges from the light receiving unit under the transfer electrode also serving as the readout is substantially equal to the center of gravity of the light receiving unit in the charge transfer direction. Imaging device. The solid-state imaging device according to claim 1, wherein the transfer electrode also serving as the readout is formed with a length in the charge transfer direction larger than that of other transfer electrodes. Two transfer electrodes, the transfer electrode also serving as the readout and the other transfer electrode, are arranged corresponding to the respective light receiving portions,
The solid-state imaging device according to claim 1, wherein the transfer electrode also serving as the readout is arranged on the upstream side in the charge transfer direction. The solid-state imaging device according to claim 3, wherein the impurity region is formed so as to gradually move away from the light receiving portion in the charge transfer direction.

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