JP2010080791A - Solid-state image sensing device and electronic instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state image sensing device whose transfer efficiency is improved by inhibiting the occurrence of a potential barrier associated with the sliming of a vertical transfer channel and an electronic instrument using the same. <P>SOLUTION: The solid-state image sensing device has multiple light-receiving sensor parts 12 formed in the horizontal and vertical directions of a substrate 15, a reader 11 for reading the signal charges accumulated in the light-receiving sensor parts 12, and a vertical transfer channel 10 for transferring the signal charges red in the vertical direction. In addition, the device has a horizontal element separator 20 formed on the other side of the horizontal direction of the light-receiving senso part 12 and a vertical element separator 13 formed on the both sides of the vertical direction of the light-receiving sensor part 12. Also, the device has a potential controller 14 formed between the vertical element separator 13 and at least one vertical transfer channel 10 of the vertical transfer channels 10 adjacent to the both ends of the vertical element separator 13. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to, for example, a CCD (Charge Coupled Device) type solid-state imaging device and an electronic apparatus including the solid-state imaging device.

  A solid-state imaging device using a charge coupled device (CCD) is known as a solid-state imaging device. In this CCD type solid-state imaging device, a plurality of light receiving sensor units are arranged in a two-dimensional matrix by photoelectric conversion elements that generate and store signal charges corresponding to the amount of received light, that is, photodiodes (PDs). It is configured. Signal charges are generated and accumulated based on the optical signal of the subject incident on the photodiodes of the plurality of light receiving sensor units. The accumulated signal charges are transferred in the vertical direction by a vertical transfer register arranged for each column of the light receiving sensor unit, and transferred in the horizontal direction by a horizontal transfer register having a CCD structure. The signal charges transferred in the horizontal direction are output as image information of the subject from an output unit having a charge-voltage conversion unit.

In the CCD type solid-state imaging device having such a structure, various problems have recently emerged as the pixel size is reduced. The following Patent Document 1 describes a configuration for preventing signal charge read efficiency from deteriorating due to thinning accompanying reduction in pixel size.
JP 2006-319184 A

  Further, in order to realize a finer pixel size, it is an essential requirement to make the vertical transfer channel constituting the vertical transfer register thinner. However, as the vertical transfer channel becomes thinner, there is a problem that the potential modulation effect due to the space charge in the impurity regions formed in the element isolation portion and the light receiving sensor portion around the vertical transfer channel increases. A configuration of a conventional solid-state imaging device and its potential distribution will be described with reference to FIGS.

  FIG. 10 shows a planar configuration of a conventional solid-state imaging device. 11A shows a cross-sectional configuration along the line A-A ′ in FIG. 10, and FIG. 11B shows a cross-sectional configuration along the line B-B ′ in FIG. 10.

The conventional solid-state imaging device includes a plurality of pixels 113 including a plurality of light receiving sensor units 108 made of photodiodes arranged in the horizontal and vertical directions, a reading unit 105, and a vertical transfer channel 100.
The light receiving sensor unit 108 includes a signal charge storage unit 106 and a hole storage region 107 formed in the p-type semiconductor well region 102 of the substrate 101 made of an n-type semiconductor. The signal charge storage unit 106 is formed of an n-type impurity region. The hole accumulation region 107 is formed of a p-type impurity region (p +) and is formed on the surface of the signal charge accumulation unit 106.
The vertical transfer channel 100 is formed of an n-type impurity region at a predetermined interval from the light receiving sensor unit.
The reading unit 105 is formed of a p-type impurity region (p) between the vertical transfer channel 100 and the light receiving sensor unit 108 on one side (right side in the figure) to be read.

  In addition, a horizontal element isolation unit 104 made of a p-type impurity region (p +) is formed between the vertical transfer channel 100 and the light receiving sensor unit 108 on the other side (left side in the figure) that is not a read target. At both ends in the vertical direction of the light receiving sensor unit 108, vertical element isolation units 103 made of p-type impurity regions (p +) are formed. The horizontal element separating unit 104 separates each light receiving sensor unit 108 in the horizontal direction, and the vertical element separating unit 103 separates each light receiving sensor unit 108 in the vertical direction. The vertical element separation unit 103, the horizontal element separation unit 104, and the reading unit 105 are formed in contact with the vertical transfer channel 100, respectively.

  On the readout unit 105 and the vertical transfer channel 100, the first transfer electrode 111 and the second transfer electrode 110 are alternately formed via the insulating film 109. The vertical transfer channel 100, the first transfer electrode 111, and the second electrode 110 constitute a vertical transfer register.

  As shown in FIG. 11A, the first transfer electrode 111 is formed on the vertical element isolation unit 103 and across the vertical transfer channel 100 adjacent to the vertical element isolation unit 103. The second transfer electrode 110 is formed in a floating island shape on the vertical transfer channel 100. The second transfer electrode 110 also serves as a readout electrode for reading out signal charges accumulated in the light receiving sensor unit 108 to the vertical transfer channel 100.

  Although not shown here, a light-shielding film that covers the transfer electrode is formed on the transfer electrode via an insulating film. An opening for exposing the light receiving sensor unit 108 is formed in the light shielding film.

  In the solid-state imaging device having the above configuration, by applying, for example, four-phase drive pulses φV1, φV2, φV3, and φV4 to the first transfer electrode 111 and the second transfer electrode 110, the potential distribution in the vertical transfer channel 100 is changed. Changed. Then, signal charges are transferred in the vertical transfer channel 100. FIG. 12 shows the potential distribution in the vertical transfer channel of the conventional solid-state imaging device. The potential distributions in the first transfer electrode 111 and the second transfer electrode 110 on the vertical transfer channel 100 and the potential distribution in the vertical transfer channel 100 under the first transfer electrode 111 and the second transfer electrode 110 are shown in correspondence with each other. FIG. 12 shows the potential distribution when only the drive pulse φV1 applied to the first transfer electrode 111 is set to the low level (L) and the other drive pulses φV2 to φV4 are set to the high level (H). .

  In the conventional solid-state imaging device, as shown in FIG. 12, in the vertical transfer channel 100, the potential is shallow at the position in contact with the vertical element isolation unit 103 due to the influence of the p-type impurity region constituting the vertical element isolation unit 103. As received. On the other hand, in the vertical transfer channel 100, at the position in contact with the light receiving sensor unit 108, modulation is performed so that the potential becomes deep due to the influence of the n-type impurity region constituting the light receiving sensor unit 108. As described above, the potential in the transfer direction in the vertical transfer channel 100 is modulated in the reverse direction depending on the location, so that a potential barrier is formed in the vertical transfer channel 100. Then, it is difficult to obtain sufficient transfer efficiency when the signal charge e is transferred.

  In particular, when the transfer length of the read / second transfer electrode 110 is increased in order to reduce the read voltage, this potential barrier is a transfer electric field E of the read / second transfer electrode 110 as shown by a broken line in FIG. Therefore, the transfer deterioration of transfer charge becomes remarkable.

  In response to such a problem, it has been proposed to change the shape of the vertical transfer channel 100 in a conventional solid-state imaging device having a large pixel size, as shown in FIG. In FIGS. 13 and 14, parts corresponding to those in FIGS. 10 and 11 are denoted by the same reference numerals, and redundant description is omitted. In the example shown in FIG. 13, a protruding portion 112 is formed by protruding a portion adjacent to the vertical element isolation portion 103 of the vertical transfer channel 100 in the direction of the vertical element isolation portion 103. That is, the n-type impurity region constituting the vertical transfer channel 100 is formed so as to enter the p-type impurity region constituting the vertical element isolation portion 103. In this manner, by partially changing the width of the vertical transfer channel 100, the influence of the p-type impurity region constituting the vertical element isolation portion 103 in the vertical transfer channel 100 can be reduced, and the potential barrier can be reduced. Can be reduced.

  However, as described above, since the thinning of the vertical transfer channel 100 is required as the pixel size is reduced, it is difficult to adjust the line width of the vertical transfer channel 100 with high accuracy. Since the variation also increases, the conventional configuration as shown in FIGS. 13 and 14 cannot be used. For this reason, it is desirable that the line width of the vertical transfer channel 100 be constant.

  In view of the above, the present invention provides a solid-state imaging device that suppresses the generation of a potential barrier associated with the thinning of a vertical transfer channel and improves transfer efficiency. In addition, the present invention provides an electronic device using the solid-state imaging device.

  In order to solve the above problems and achieve the object of the present invention, the solid-state imaging device of the present invention first has a plurality of light receiving sensor sections formed in the horizontal and vertical directions of the substrate. And it has the read-out part for reading the signal charge accumulate | stored in the light-receiving sensor part, and the vertical transfer channel for transferring the read signal charge to a perpendicular direction. The reading unit is formed on one side of the light receiving sensor unit in the horizontal direction. The vertical transfer channel is formed in a vertical direction in a region between adjacent light receiving sensor portions. And it has the horizontal element isolation | separation part formed in the other side of the horizontal direction of a light reception sensor part, and the vertical element isolation | separation part formed in the both sides of the vertical direction of a light reception sensor part. In addition, a potential adjustment unit is formed between the vertical element isolation unit and at least one of the vertical transfer channels adjacent to both ends of the vertical element isolation unit.

  In the solid-state imaging device of the present invention, a potential adjustment unit is formed between the vertical transfer channel and the vertical element separation unit, thereby suppressing the potential barrier in the potential distribution in the transfer direction in the vertical transfer channel. be able to.

The electronic apparatus according to the present invention includes an optical lens, a solid-state imaging device, and a signal processing circuit.
The solid-state imaging device has a plurality of light receiving sensor portions formed in the horizontal direction and the vertical direction of the substrate. And it has the read-out part for reading the signal charge accumulate | stored in the light-receiving sensor part, and the vertical transfer channel for transferring the read signal charge to a perpendicular direction. The reading unit is formed on one side of the light receiving sensor unit in the horizontal direction. The vertical transfer channel is formed in a vertical direction in a region between adjacent light receiving sensor portions. And it has the horizontal element isolation | separation part formed in the other side of the horizontal direction of a light reception sensor part, and the vertical element isolation | separation part formed in the both sides of the vertical direction of a light reception sensor part. In addition, a potential adjustment unit is formed between the vertical element isolation unit and at least one of the vertical transfer channels adjacent to both ends of the vertical element isolation unit.

  In the electronic apparatus of the present invention, in the solid-state imaging device constituting the electronic apparatus, a potential adjustment unit is formed between the vertical transfer channel and the vertical element separation unit. Thereby, in the solid-state imaging device, the potential barrier can be suppressed in the potential distribution in the transfer direction in the vertical transfer channel.

  According to the present invention, it is possible to obtain a solid-state imaging device capable of thinning a vertical transfer channel and improving the signal charge transfer efficiency by suppressing the generation of a potential barrier in the potential distribution of the vertical transfer channel. It is done.

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

First, FIG. 1 shows an overall configuration of a CCD type solid-state imaging device, which is a common configuration in the following embodiments.
As shown in FIG. 1, a CCD type solid-state imaging device 1 includes a plurality of light receiving sensor portions 12 formed in a horizontal direction and a vertical direction of a substrate 6, a vertical transfer register 3 having a CCD structure, and a horizontal transfer having a CCD structure. A register 4 and an output circuit 5 are included. The light receiving sensor unit 12 is configured by a photoelectric conversion element, that is, a photodiode, and generates and accumulates signal charges. The vertical transfer register 3 is formed in a plurality in the vertical direction corresponding to the light receiving sensor units 12 arranged in the vertical direction, reads out the signal charges accumulated in the light receiving sensor unit 12 and transfers them in the vertical direction. To do. The horizontal transfer register 4 is formed, for example, at one end of the vertical transfer register 3 and transfers the signal charge vertically transferred by the vertical transfer register 3 for each horizontal line. Each pixel 2 is configured by each light receiving sensor unit 12 and the vertical transfer register 3 adjacent to the light receiving sensor unit 12. The output circuit 5 outputs a pixel signal by converting the signal charge horizontally transferred by the horizontal transfer register 4 into a charge voltage.

  In the embodiment described below, an area composed of the light receiving sensor unit 12 and the vertical transfer register 3 will be described as a main part.

<First Embodiment>
FIG. 2 shows a schematic plan configuration of the main part of the solid-state imaging device according to the first embodiment of the present invention. 3A shows a cross-sectional configuration along the line AA ′ in FIG. 2, and FIG. 3B shows a cross-sectional configuration along the line BB ′ in FIG.

[Constitution]
The solid-state imaging device according to this embodiment includes a plurality of light receiving sensor units 12 formed on a substrate 15, a reading unit 11 for reading signal charges accumulated in the light receiving sensor unit 12, and a light receiving sensor unit 12 as a unit pixel. It has a horizontal element separation unit 20 and a vertical element separation unit 13 that separate every two, and a vertical transfer channel 10 that transfers signal charges. A potential adjustment unit 14 is provided between the vertical element isolation unit 13 and the vertical transfer channel 10.

  In this embodiment, the substrate 15 is an n-type (first conductivity type) semiconductor substrate. The light receiving sensor unit 12, the reading unit 11, the vertical element isolation unit 13, the horizontal element isolation unit 20, the vertical transfer channel 10, and the potential adjustment unit 14 formed on the substrate 15 are p-type (first type) formed on the substrate 15. It is formed on the upper surface of the well region 16 made of an impurity region of (2 conductivity type).

  A plurality of light receiving sensor units 12 are arranged on the upper surface of the well region 16 in the vertical direction and the horizontal direction. The light receiving sensor unit 12 includes a signal charge storage unit 21 formed of an n-type impurity region and a hole storage region 22 formed of a p-type impurity region formed on the surface of the signal charge storage unit 21. Yes. In the light receiving sensor unit 12, a buried photodiode is configured by a pn junction between the signal charge storage unit 21 made of an n-type impurity region and the well region 16 made of a p-type impurity region. Then, the hole accumulation region 22 is formed by the p-type impurity region on the surface of the signal charge accumulation unit 21, thereby obtaining a photodiode in which dark current is suppressed.

The readout unit 11 is formed of a p-type impurity region (p) on one side of the light receiving sensor unit 12 in the horizontal direction (left side in FIG. 2).
The horizontal element separation unit 20 is formed by a p-type impurity region (p +) on the other side in the horizontal direction of the light receiving sensor unit 12 (right side in FIG. 2).
The vertical element separation unit 13 is formed by p-type impurity regions (p +) on both sides of the light receiving sensor unit 12 in the vertical direction (up and down in FIG. 2).
Here, the impurity concentration of the impurity region (p) constituting the readout unit 11 is lower than the impurity concentration of the impurity region (p +) constituting the horizontal element isolation unit 20 and the vertical element isolation unit 13.

  Each light receiving sensor unit 12 is surrounded by a reading unit 11, a horizontal element separating unit 20, and a vertical element separating unit 13.

  The vertical transfer channel 10 is formed with a constant width in the vertical direction in a region between the light receiving sensor units 12 adjacent in the horizontal direction. The vertical transfer channel 10 is configured as an embedded vertical transfer channel by an n-type impurity region. The vertical transfer channel 10 and the readout unit 11 and the horizontal element isolation unit 20 adjacent to the vertical transfer channel 10 are formed in contact with each other. The n-type impurity region constituting the vertical transfer channel 10 has a relatively higher impurity concentration than the signal charge storage unit 21. Accordingly, the potential becomes shallow due to the modulation of the vertical element separation unit 13, thereby causing a step in the potential of the vertical transfer channel 10.

  The potential adjustment unit 14 is formed between the vertical element isolation unit 13 and the vertical transfer channel 10 adjacent to both ends of the vertical element isolation unit 13 in the horizontal direction. The potential adjustment unit 14 is configured in a region formed by separating the vertical element isolation unit 13 and the vertical transfer channel 10 adjacent to the vertical element isolation unit 13 by a predetermined distance. That is, the potential adjusting unit 14 is formed between the vertical element isolation unit 13 and the vertical transfer channel 10 formed by separating the vertical element isolation unit 13 and the adjacent vertical transfer channel 10 from each other by a predetermined distance. The area itself is shown. The horizontal width W of the potential adjustment unit 14 is a distance between the vertical transfer channel 10 and the end of the vertical element isolation unit 13 adjacent to the vertical transfer channel 10. The width W of the potential adjusting unit 13 is determined by how far the vertical element separating unit 13 is formed from the vertical transfer channel 10.

  The potential adjusting unit 14 is provided to suppress a potential barrier generated in the vertical potential distribution in the vertical transfer channel 10. Therefore, it is possible to prevent the vertical potential in the vertical transfer channel 10 from being modulated in a shallow direction due to the influence of the p-type impurity region at a position corresponding to the vertical element isolation portion 13 of the vertical transfer channel 10. it can.

  The preferred width W of the potential adjusting unit 14 is a width that eliminates the potential barrier generated in the potential distribution in the vertical direction of the vertical transfer channel 10, which is the vertical transfer channel 10, the vertical element isolation unit 13, and the like. It depends on the impurity concentration. For example, when the width of the vertical transfer channel 10 is 0.3 μm, if the width W of the potential adjustment unit 14 is 0.03 μm, which is 10% of the width of the vertical transfer channel 10, the vertical transfer channel 10. The inner potential barrier is eliminated. That is, in this case, the vertical element isolation portion 13 may be formed away from the vertical transfer channel 10 by about 0.03 μm.

  A first transfer electrode 18 and a second transfer electrode 19 are formed via an insulating film 17 on the substrate 15 on which the vertical transfer channel 10 and the reading unit 11 are formed. The first transfer electrode 18 is formed to extend in the horizontal direction on the vertical element isolation unit 13 and the vertical transfer channel 10, and is formed so as to protrude slightly in the vertical direction on the vertical transfer channel 10. . The second transfer electrode 19 also serves as a readout electrode, and is formed in a floating island shape on the readout unit 11 and the vertical transfer channel 10 in contact with the readout unit 11. The first transfer electrodes 18 and the second transfer electrodes 10 are alternately formed on the substrate 15 in the vertical direction. The first transfer electrode 18 and the second transfer electrode 19 can be formed of, for example, polycrystalline silicon, and can be formed in a single layer.

  The vertical transfer channel 3, the first transfer electrode 18, and the second transfer electrode 19 constitute the vertical transfer register 3 shown in FIG. Further, the light receiving sensor unit 12 surrounded by the vertical element separating unit 13 and the horizontal element separating unit 20, and the reading unit 11 and the vertical transfer channel 10 for reading and transferring the signal charges accumulated in the light receiving sensor unit 12; The unit pixel 2 is configured.

[Operation during read / transfer]
In the above-described solid-state imaging device of this embodiment, signal charges are read and transferred by applying, for example, four-phase drive pulses φV1, φV2, φV3, and φV4 to the first transfer electrode 18 and the second transfer electrode 19. Is made. In this embodiment, drive pulses φV1, φV2, φV3, and φV4 are sequentially applied to the first transfer electrode 18, the second transfer electrode 19, the first transfer electrode 18, and the second transfer electrode 19 arranged in the vertical direction. To do.

  First, a signal charge is read from the signal charge storage unit 21 to the vertical transfer channel 10 by applying a read pulse to the second transfer electrode 19 that also serves as a read electrode. Then, by applying the drive pulses φV1 to φV4 with the phases shifted to the first transfer electrode 18 and the second transfer electrode 19 arranged in the transfer direction, signal charges are generated in the vertical transfer channel 10. Transferred. Then, the signal charge transferred through the vertical transfer channel 10 is transferred in the horizontal direction by the horizontal transfer register 3 shown in FIG. 1, and the signal charge is converted into an electric signal by the output circuit 5 and output as an image signal. .

  FIG. 4 shows a potential distribution in the transfer direction of the vertical transfer channel 10 in the solid-state imaging device of the present embodiment. A potential distribution in the first transfer electrode 18 and the second transfer electrode 19 on the vertical transfer channel 10 and the potential distribution in the vertical transfer channel 10 under the first transfer electrode 18 and the second transfer electrode 19 are shown in correspondence with each other.

FIG. 4 is a diagram when only the drive pulse φV1 is set to the low level (L) and the other drive pulses φV2 to φV4 are set to the high level (H).
As shown in FIG. 4, in the solid-state imaging device of this embodiment, a potential adjustment unit 14 is formed between the vertical element separation unit 13 and the vertical transfer channel 10 adjacent to the vertical element separation unit 13. Yes. The potential adjusting unit 14 reduces the influence of the vertical element isolation unit 13 made of a p-type impurity region on the vertical transfer channel 10. For this reason, it is possible to prevent the potential in the transfer direction of the vertical transfer channel 10 from being modulated in the shallow direction due to the influence of the p-type impurity region constituting the vertical element isolation portion 13. In this embodiment, the vertical transfer channel 10 and the reading unit 11 and the horizontal element isolation unit 20 adjacent to the vertical transfer channel 10 are formed so as to be in contact with each other.

  With the above configuration, the potential barrier that causes the transfer efficiency to deteriorate in the potential distribution in the transfer direction in the vertical transfer channel 10 is eliminated. This makes it possible to obtain a sufficient signal charge e transfer efficiency even when the vertical transfer channel 10 is thinned. Moreover, since the potential barrier is eliminated, an electric field E larger than that of the conventional structure can be obtained.

  In the solid-state imaging device according to the present embodiment, since the vertical transfer channel 10 is formed with a constant width, manufacturing variations can be reduced even when the vertical transfer channel 10 is thinned. Further, the potential adjustment unit 14 can be formed by forming the vertical element isolation unit 13 away from the vertical transfer channel 10 by a predetermined distance. Thereby, the potential adjusting unit 14 can be formed only by changing the formation pattern when the vertical element separating unit 13 is formed by ion implantation, and the number of processes does not increase.

  By the way, in this embodiment, the width W of the potential adjustment unit 14 is set to a width that can suppress the potential barrier in the transfer direction of the vertical transfer channel 10, but by adjusting the width W of the potential adjustment unit 14, a desired width can be obtained. Potential distribution. For example, by adjusting the width W of the potential adjusting unit 14, the potential in the vertical transfer channel 10 below the first transfer electrode 18 is made deeper than the potential in the vertical transfer channel 10 below the second transfer electrode 19 that also serves as a readout electrode. Can be set. The width W of the potential adjusting unit 14 depends on the impurity concentration of the vertical transfer channel 10 and the vertical element isolation unit 13. For example, when the width of the vertical transfer channel 10 is 0.3 μm, the vertical transfer channel 10 It is formed to be larger than 0.03 μm which is 10% of the width of 10. In other words, when the vertical element isolation portion 13 is formed away from the vertical transfer channel 10 by more than 0.03 μm, the potential in the vertical transfer channel 10 under the second transfer electrode 19 also serving as the readout electrode is lower than that in the first transfer electrode 18. The potential in the vertical transfer channel 10 can be set deep.

  When the length of the first transfer electrode 18 formed on the vertical transfer channel 10 adjacent to the vertical element separation unit 13 is set to be shorter than the length of the second transfer electrode 19 that also serves as a readout electrode, the length is longer than that of the second transfer electrode 19. It is possible to increase the electric field. For this reason, the electric field E in the vertical transfer channel 10 can be made larger than that in the conventional structure by setting the potential in the vertical transfer channel 10 below the first transfer electrode 18 deep. That is, by setting the length of the first transfer electrode 18 to be shorter than the second electrode length 19 also serving as a read electrode, the width of the read unit 11 for reading a signal from the signal charge storage unit 21 to the vertical transfer channel 10 is increased. Charges can be easily read out.

<Second Embodiment>
FIG. 5 shows a schematic plan configuration of a main part of a solid-state imaging device according to the second embodiment of the present invention. 6A shows a cross-sectional configuration along the line AA ′ in FIG. 5, and FIG. 6B shows a cross-sectional configuration along the line BB ′ in FIG. 5 and 6, parts corresponding to those in FIGS.

[Constitution]
In the solid-state imaging device according to the present embodiment, a potential adjustment unit 14 is formed between the end of the vertical element separation unit 13 on the readout unit 11 side and the vertical transfer channel 10 adjacent to the end of the vertical element separation unit 13. Has been. The end of the vertical element isolation unit 13 on the horizontal element isolation unit 20 side and the vertical transfer channel 10 adjacent to the end of the vertical element isolation unit 13 are arranged so as to contact each other.
The potential adjustment unit 14 forms the vertical element isolation unit 13 such that the end of the vertical element isolation unit 13 on the reading unit 11 side is separated from the vertical transfer channel 10 adjacent to the end by a predetermined distance. It is formed by.

  The width W of the potential adjusting unit 14 in the present embodiment is set to a width that eliminates the potential barrier generated in the potential distribution in the vertical direction of the vertical transfer channel 10.

  As described above, even when the potential adjustment unit 14 is formed only between one end of the vertical element isolation unit 13 and the vertical transfer channel 10, the transfer in the vertical transfer channel 10 is performed as in the first embodiment. In the potential distribution in the direction, it is possible to eliminate the potential barrier that causes the transfer efficiency to deteriorate. This makes it possible to obtain sufficient transfer efficiency even when the vertical transfer channel 10 is thinned.

  Also in the present embodiment, the width W of the potential adjustment unit 14 is set to a width that can suppress the potential barrier in the transfer direction of the vertical transfer channel 10, but by adjusting the width W of the potential adjustment unit 14, a desired width can be obtained. It can be a potential distribution. For example, by adjusting the width W of the potential adjusting unit 14, the potential in the vertical transfer channel 10 below the first transfer electrode 18 is made deeper than the potential in the vertical transfer channel 10 below the second transfer electrode 19 that also serves as a readout electrode. Can be set. When the length of the first transfer electrode 18 formed on the vertical transfer channel 10 adjacent to the vertical element separation unit 13 is set to be shorter than the length of the second transfer electrode 19 that also serves as a readout electrode, the length is longer than that of the second transfer electrode 19. It is possible to increase the electric field. For this reason, by setting the potential in the vertical transfer channel 10 below the first transfer electrode 18 deep, the electric field in the vertical transfer channel 10 can be made larger than that in the conventional structure.

[Third Embodiment]
FIG. 7 shows a schematic plan configuration of a main part of a solid-state imaging device according to the third embodiment of the present invention. 8A shows a cross-sectional configuration along the line AA ′ in FIG. 7, and FIG. 7B shows a cross-sectional configuration along the line BB ′ in FIG. 7 and 8, parts corresponding to those in FIGS. 2 and 3 are denoted by the same reference numerals, and redundant description is omitted.

[Constitution]
The solid-state imaging device according to the present embodiment includes a potential adjusting unit 14 between the end of the vertical element separating unit 13 on the horizontal element separating unit 20 side and the vertical transfer channel 10 adjacent to the end of the vertical element separating unit 13. Is formed. The end of the vertical element separation unit 13 on the reading unit 11 side and the vertical transfer channel 10 adjacent to the end of the vertical element separation unit 13 are arranged so as to contact each other.
The potential adjustment unit 14 forms the vertical element isolation unit 13 such that the end of the vertical element isolation unit 13 on the horizontal element isolation unit 20 side is separated from the vertical transfer channel 10 adjacent to the end by a predetermined distance. It is formed by doing.

  The width W of the potential adjusting unit 10 in this embodiment is set to a width that eliminates the potential barrier generated in the potential distribution in the vertical direction of the vertical transfer channel 10.

  Thus, even when the potential adjustment unit 14 is formed only between one end of the vertical element isolation unit 13 and the vertical transfer channel 10, the transfer direction in the vertical transfer channel 10 is the same as in the first embodiment. In this potential distribution, it is possible to eliminate the potential barrier that causes the transfer efficiency to deteriorate. This makes it possible to obtain sufficient transfer efficiency even when the vertical transfer channel 10 is thinned.

  Also in the present embodiment, the width W of the potential adjustment unit 14 is set to a width that can suppress the potential barrier in the transfer direction of the vertical transfer channel 10, but by adjusting the width W of the potential adjustment unit 14, a desired width can be obtained. It can be a potential distribution. For example, by adjusting the width W of the potential adjusting unit 14, the potential in the vertical transfer channel 10 below the first transfer electrode 18 is made deeper than the potential in the vertical transfer channel 10 below the second transfer electrode 19 that also serves as a readout electrode. Can be set. When the length of the first transfer electrode 18 formed on the vertical transfer channel 10 adjacent to the vertical element separation unit 13 is set to be shorter than the length of the second transfer electrode 19 that also serves as a readout electrode, the length is longer than that of the second transfer electrode 19. It is possible to increase the electric field. For this reason, by setting the potential in the vertical transfer channel 10 below the first transfer electrode 18 deep, the electric field in the vertical transfer channel 10 can be made larger than that in the conventional structure.

  In the solid-state imaging device of the present invention, as shown in the first to third embodiments, at least one of the vertical element separation unit 13 and the vertical transfer channel 10 adjacent to both ends of the vertical element separation unit 13 is used. A potential adjusting unit 14 is formed between the vertical transfer channel 10. The potential adjustment unit 14 can reduce the influence of the impurity region (p +) constituting the vertical element isolation unit 13 on the vertical transfer channel 10 and suppress the generation of a potential barrier.

  The potential adjustment unit 14 forms the vertical element isolation unit 13 so that at least one end in the horizontal direction of the vertical element isolation unit 13 is separated from the adjacent vertical transfer channel 10 by a predetermined distance. Is formed. For this reason, it is not necessary to change the line width of the vertical transfer channel 10, and the number of processes does not increase. As a result, when the vertical transfer channel 10 is thinned, the line width can be formed with high accuracy, and variations in manufacturing can be reduced.

[Electronics]
Hereinafter, an embodiment in which the solid-state imaging device according to the first to third embodiments of the present invention described above is used in an electronic apparatus will be described. In the following description, an example in which the solid-state imaging device 1 configured in the first to third embodiments is used as a camera will be described as an example.

  FIG. 9 shows a schematic cross-sectional configuration of a camera according to an embodiment of the present invention. The camera according to the present embodiment is an example of a video camera capable of capturing still images or moving images.

  The camera according to this embodiment includes a solid-state imaging device 1, an optical system 210, a shutter device 211, a drive circuit 212, and a signal processing circuit 213.

The optical system 210 forms image light (incident light) from the subject on the upper surface of the imaging surface of the solid-state imaging device 1. Thereby, signal charges are accumulated in the solid-state imaging device 1 for a certain period.
The shutter device 211 controls a light irradiation period and a light shielding period for the solid-state imaging device 1.
The drive circuit 212 supplies a drive signal that controls the transfer operation of the solid-state imaging device 1 and the shutter operation of the shutter device 211. Signal transfer of the solid-state imaging device 1 is performed by a drive signal (timing signal) supplied from the drive circuit 212. The signal processing circuit 213 performs various signal processing. The video signal subjected to the signal processing is stored in a storage medium such as a memory or output to a monitor.

  In the camera of the present embodiment, by using the solid-state imaging device with high transfer efficiency described in the first to third embodiments, there is an effect that an image with less noise is obtained.

It is a schematic block diagram of the solid-state imaging device in the 1st-3rd embodiment of this invention. 1 is a schematic plan configuration diagram of a solid-state imaging device according to a first embodiment of the present invention. FIGS. 3A and 3B are a schematic cross-sectional configuration diagram along line A-A ′ in FIG. 2 and a schematic cross-sectional configuration diagram along line B-B ′. FIG. 3 is a potential distribution diagram in a vertical transfer channel of the solid-state imaging device according to the first embodiment. It is a schematic plane block diagram of the solid-state imaging device in the 2nd Embodiment of this invention. FIGS. 6A and 6B are a schematic cross-sectional configuration diagram along line A-A ′ in FIG. 5 and a schematic cross-sectional configuration diagram along line B-B ′. It is a schematic plane block diagram of the solid-state imaging device in the 3rd Embodiment of this invention. FIGS. 8A and 8B are a schematic cross-sectional configuration diagram along line A-A ′ in FIG. 7 and a schematic cross-sectional configuration diagram along line B-B ′. It is a schematic block diagram of the electronic device in one Embodiment of this invention. It is a schematic plane block diagram of the solid-state imaging device of a prior art example. FIGS. 10A and 10B are a schematic cross-sectional configuration diagram along line A-A ′ in FIG. 9 and a schematic cross-sectional configuration diagram along line B-B ′. It is a potential distribution map in the vertical transfer channel of the conventional solid-state imaging device. It is a schematic plane block diagram of the solid-state imaging device of a prior art example. FIGS. 12A and 12B are a schematic cross-sectional configuration diagram along the line A-A ′ in FIG. 11 and a schematic cross-sectional configuration diagram along the line B-B ′.

Explanation of symbols

  1 .... Solid-state imaging device 2 .... Unit pixel 3 .... Vertical transfer register 4 .... Horizontal transfer register 5 .... Output circuit 10 .... Vertical transfer channel 11 .... Reading unit 12 .... Light receiving Sensor part, 13 .. Vertical element separation part, 14 .. Potential adjustment part, 15 .. Substrate, 16 .. Well region, 17 .. Insulating phase, 18 .. First transfer electrode, 19. , 20 .. Horizontal element separation part, 21 .. Signal charge storage part, 22 .. Hole storage area

Claims (8)

A plurality of light receiving sensor portions formed in the horizontal direction and the vertical direction of the substrate;
In order to read out the signal charges accumulated in the light receiving sensor unit, a reading unit formed on one side in the horizontal direction of the light receiving sensor unit;
A vertical transfer channel formed in a vertical direction in a region between the adjacent light receiving sensor units in order to transfer the signal charges read by the read unit in the vertical direction;
A horizontal element separating portion formed on the other side in the horizontal direction of the light receiving sensor portion;
Vertical element separation parts formed on both sides of the light receiving sensor part in the vertical direction;
A potential adjustment unit formed between the vertical element isolation unit and at least one of the vertical transfer channels adjacent to both ends of the vertical element isolation unit;
A solid-state imaging device. The solid-state imaging device according to claim 1, wherein the potential adjustment unit includes a region formed by separating the vertical element separation unit from the vertical transfer channel by a predetermined distance. 3. The solid according to claim 2, wherein the vertical transfer channel is configured by a first conductivity type impurity region, and the vertical element isolation unit, the horizontal element isolation unit, and the readout unit are configured by a second conductivity type impurity region. Imaging device. The solid-state imaging device according to claim 3, wherein the predetermined distance configuring the potential adjustment unit is set to a distance in which a vertical potential distribution in a vertical transfer channel does not have a potential barrier. The solid-state imaging device according to claim 4, wherein a width of the vertical transfer channel is constant. The solid-state imaging device according to claim 5, wherein the readout unit, the horizontal element separation unit, and the vertical transfer channel are formed in contact with each other. The predetermined distance constituting the potential adjustment unit is set to a distance at which the potential of the vertical transfer channel adjacent to the vertical element isolation unit is modulated deeper than the potential of the vertical transfer channel adjacent to the readout unit. 3. The solid-state imaging device according to 3. An optical lens,
A plurality of light receiving sensor portions formed in a horizontal direction and a vertical direction of the substrate; and a reading portion formed on one side in the horizontal direction of the light receiving sensor portion in order to read signal charges accumulated in the light receiving sensor portion; In order to transfer the signal charges read by the reading unit in the vertical direction, a vertical transfer channel formed in a vertical direction in an area between the adjacent light receiving sensor units, and a horizontal direction of the light receiving sensor unit A horizontal element separation part formed on the other side, a vertical element separation part formed on both sides in the vertical direction of the light receiving sensor part, the vertical element separation part, and both ends of the vertical element separation part A solid-state imaging device including a potential adjustment unit formed between at least one of the adjacent vertical transfer channels; and
A signal processing circuit for processing an output signal of the solid-state imaging device;
Electronic equipment having

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