JP2013125799A - Solid-state imaging device and electronic information apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a solid-state imaging device capable of effectively improving degradation in transfer efficiency caused by an unsharpened waveform of a drive signal for driving a vertical transfer part without increase in the number of manufacturing steps.SOLUTION: A solid-state imaging device has: a plurality of pixel parts; and a plurality of vertical transfer parts transferring signal charge generated by the pixel parts in a vertical direction. In the solid-state imaging device, the pixel parts and the vertical transfer parts form an imaging region. In the solid-state imaging device, the vertical transfer parts 121-125 are formed so as to be overlapped with a vertical transfer channel region, and respectively have orientation regions R1-R5 inclining potential levels formed at the vertical transfer channel region so as to decide a transfer direction of the signal charge. Planar shapes of the orientation regions are set so that the inclination of each potential level at the plurality of vertical transfer parts becomes gentler as the position of each vertical transfer part becomes closer to a central part of the imaging region.

Description

  The present invention relates to a solid-state imaging device and an electronic information device, and more particularly, to a solid-state imaging device with improved transfer efficiency in a vertical transfer unit and an electronic information device including such a solid-state imaging device.

  Conventionally, solid-state imaging devices include a CCD solid-state imaging device and a CMOS solid-state imaging device. In the CCD solid-state imaging device, an imaging region is included in a transfer electrode of a vertical transfer unit (hereinafter referred to as a vertical transfer electrode). A drive signal (hereinafter also referred to as a drive pulse) is applied from the bus line at both ends of the vertical transfer electrode extending to the outside of the electrode.

  However, a propagation delay of the drive pulse occurs in the vertical transfer electrode, and the vertical transfer electrode is formed at the periphery of the imaging region near the connection point between the bus line and the vertical transfer electrode and at the center of the imaging region far from the bus line. The waveform of the applied drive pulse is significantly different, and it is difficult to obtain transfer characteristics as designed over the entire imaging region.

  Such fluctuations in the transfer characteristics due to the rounded waveform of the drive pulse could be absorbed to some extent because there was a transfer characteristic margin when the pixel size was large, but when the pixel size is small, for example, it is 2 μm or less. Then, the deterioration of characteristics such as vertical transfer efficiency and dark current due to the fluctuation of the transfer characteristics becomes obvious and cannot be ignored.

  Conventionally, such a problem of transfer characteristic deterioration due to rounding of the drive pulse waveform of the vertical drive unit has been addressed. For example, Patent Document 1 discloses such a problem as a resistance value of a vertical transfer electrode. Has been solved by changing between the central part and the peripheral part of the imaging region.

  12 to 14 are diagrams for explaining a conventional CCD solid-state imaging device disclosed in Patent Document 1. FIG. 12 schematically shows an overall configuration of a conventional CCD solid-state imaging device, and FIG. FIG. 14 is a diagram for explaining the arrangement of vertical transfer electrodes and pixel portions in a vertical transfer portion (portion A in FIG. 12) of a conventional CCD solid-state imaging device, and FIG. 14 is a vertical transfer of the conventional CCD solid-state imaging device. 12 shows the arrangement of vertical transfer electrodes and transfer channels (hereinafter referred to as vertical transfer channel regions) in the section (A portion in FIG. 12).

  This CCD type solid-state imaging device (hereinafter referred to as a solid-state imaging device) 1 is provided along a plurality of pixel units 1a arranged in a matrix and along each column of the plurality of pixel units 1a. A plurality of vertical transfer units 2 that transfer signal charges obtained by photoelectric conversion in the vertical direction, and signals that are arranged on one end side of these vertical transfer units 2 and transferred from the pixel unit 1a by the vertical transfer unit 2 It has a horizontal transfer unit 3 that transfers charges in the horizontal direction, and an output unit 4 that converts the signal charges transferred from the horizontal transfer unit 3 into voltage signals, amplifies them, and outputs them. Here, the pixel unit 1a and the vertical transfer unit 2 constitute an imaging region 1b, and the pixel unit 1a includes a photoelectric conversion element such as a photodiode as a light receiving unit. The vertical transfer unit is driven by four-phase drive signals ΦV1 to ΦV4. In the imaging region 1b, the green color filter G, the blue color filter B, and the red color filter R are in a Bayer array.

  Further, as shown in FIG. 14, vertical transfer electrodes 2 a to 2 d are arranged in the imaging region 1 b along the vertical transfer channel region 20 constituting the vertical transfer units 21 to 25 (vertical transfer unit 2 in FIG. 12). ing. These vertical transfer electrodes 2a to 2d are made of a conductive film (for example, a polysilicon film containing conductive impurities) formed on a semiconductor substrate via an insulating film, and the planar shape thereof crosses the imaging region. It has a shape extending in the direction (horizontal direction) intersecting the vertical transfer channel region so as not to overlap the light receiving part (pixel part). As shown in FIG. 13, the voltages of the four-phase drive signals φV1 to φV4 are applied to both ends of the vertical transfer electrodes 2a to 2d extending to the outside of the imaging region 1b, as shown in FIG. It has come to be.

  Further, each of the vertical transfer electrodes 2a to 2d has a low resistance value at a portion located in the central portion A3 of the imaging region 1b, and has a resistance at both side portions (that is, portions close to the bus line) A1 and A5 in the imaging region 1b. The value is high, and the resistance value is a medium value in the portions A2 and A4 between the central portion and both side portions. That is, each of the vertical transfer electrodes 2a to 2d has a structure in which the resistance value increases from the center to both sides (right and left sides of the paper) in the imaging region 1b. In FIG. 14, the vertical transfer unit 2 in the central part A3 of the imaging region 1b is a vertical transfer unit 23, the vertical transfer units 2 of both sides A1 and A5 of the imaging region 1b are vertical transfer units 21 and 25, and the imaging region. The vertical transfer portions 2 of the portions A2 and A4 between the central portion 1b and both side portions are shown as vertical transfer portions 22 and 24, respectively. In FIG. 14, the bus lines Bs1 to Bs4 shown in FIG. 13 are omitted.

  In this way, the vertical transfer electrode having a structure in which the resistance value is changed from the center part of the imaging region to both side parts (left and right side parts of the paper surface) is selectively ion-implanted with respect to the polysilicon film constituting the vertical transfer electrode. It can be formed by performing a plurality of times so that portions having different resistance values are formed.

  In the solid-state imaging device having such a configuration, the resistance value of the vertical transfer electrode is increased as it approaches the both sides from the central portion in the horizontal direction. Therefore, the vertical transfer electrode is driven between the central portion and the peripheral portion of the imaging region. The difference in the waveform of the drive pulse is reduced, which suppresses deterioration in characteristics such as vertical transfer efficiency and dark current due to rounding of the waveform of the drive pulse due to signal delay.

  Further, in Patent Document 1, by changing the wiring width and wiring thickness of the vertical transfer electrode extending in the horizontal direction, the resistance value of the vertical transfer electrode is lowered at the center in the horizontal direction of the imaging region. A method of increasing the height on both sides in the horizontal direction is disclosed. In this method, the polysilicon film constituting the vertical transfer electrode is selectively heat-treated a plurality of times to change the thickness of the surface oxidation portion of the polysilicon film, thereby reducing the wiring width and the wiring thickness of the vertical transfer electrode. The horizontal direction of the imaging region is changed from the central portion in the horizontal direction to both side portions of the imaging region in the horizontal direction.

JP 2008-1441045 A

  However, the method disclosed in Patent Document 1 is such that the resistance value of the vertical transfer electrode extending in the horizontal direction in the conventional solid-state image pickup device is increased as the portion is closer to both sides of the imaging region. A selective ion implantation process is performed multiple times on the polysilicon film to form portions with different resistance values. In an actual solid-state imaging device, a large number of vertical transfer units are arranged in the horizontal direction. The drive pulse waveform is gradually dulled toward the vertical transfer portion closer to the center portion. Therefore, the vertical transfer electrodes extending in the horizontal direction are provided at the portions corresponding to the respective vertical transfer portions. It is very difficult to perform the ion implantation process so as to have a resistance value corresponding to the rounding of the driving pulse. Further, even if the adjacent vertical transfer units are set as one group and the vertical transfer unit in the solid-state imaging device is divided into a plurality of sets and the resistance value of the vertical transfer electrode is adjusted for each set, a plurality of ion implantation processes are performed. In this case, the transfer characteristics are deteriorated due to the difference in the waveform of the drive pulse in the plurality of vertical transfer units in each group. In order to reduce the difference in the waveform of the drive pulse in the vertical transfer section in each group, more ion implantation processes are required and the number of processes increases, so that eventually the drive pulse in the vertical transfer section It is expected to be difficult to realize a solid-state imaging device that improves the deterioration of transfer characteristics due to the difference in waveform.

  Furthermore, in the method of changing the wiring width and wiring thickness of the vertical transfer electrode extending in the horizontal direction, the width and thickness of the vertical transfer electrode are close to the processing limit in a solid-state imaging device that has been miniaturized, and the resistance value is adjusted accurately. There is also a problem that it is difficult to do.

  The present invention has been made to solve the above-described problems, and effectively reduces transfer efficiency deterioration due to rounding of the waveform of a drive signal for driving a vertical transfer unit without increasing the number of manufacturing steps. It is an object of the present invention to obtain a solid-state imaging device that can be improved, and an electronic information device including such a solid-state imaging device.

  A solid-state imaging device according to the present invention includes a plurality of pixel units that are arranged in a matrix and generate signal charges by photoelectric conversion of incident light, and are provided for each column of the plurality of pixel units. And a plurality of vertical transfer units that transfer the signal charges generated in the vertical direction, the pixel unit and the vertical transfer unit forming an imaging region, the vertical transfer unit, A vertical transfer channel region formed as a transfer path of the signal charge along the vertical direction on the semiconductor substrate, and formed to overlap the vertical transfer channel region on the semiconductor substrate, and formed in the vertical transfer channel region And an orientation region that inclines the potential level so as to determine the direction of transfer of the signal charge, and the planar shape of the orientation region has an inclination of the potential level in the plurality of vertical transfer portions. , The position of the vertical transfer portion is set to be gentle closer to the center portion of the imaging region, the object is achieved.

  The present invention provides the solid-state imaging device, further comprising a plurality of vertical transfer electrodes arranged along the vertical direction on the imaging region, wherein each of the plurality of vertical transfer electrodes corresponds to the plurality of vertical transfer channel regions. Preferably, it is formed across each vertical transfer channel region so as to straddle.

  In the solid-state imaging device, the present invention provides a plurality of unit transfer electrodes arranged on each vertical transfer channel region of each of the plurality of vertical transfer units, and each vertical transfer channel region straddling the plurality of vertical transfer channel regions. It is preferable that a plurality of transfer wirings are formed across the two, and the transfer wirings are connected to the unit transfer electrodes facing the transfer wirings by contact portions to form a plurality of vertical transfer electrodes.

  In the solid-state imaging device according to the aspect of the invention, it is preferable that the unit transfer electrode is formed of a polysilicon film, and the transfer wiring is a metal wiring made of a metal material.

  In the solid-state imaging device according to the aspect of the invention, it is preferable that the directing region is formed in a portion facing each of the plurality of vertical transfer electrodes in the vertical transfer channel region.

  In the solid-state imaging device according to the present invention, the directing region is a P-type impurity region formed by injecting a P-type impurity into the semiconductor substrate. In the charge transfer channel region, the directing region is provided for each vertical transfer electrode. It is preferable that the potential level is inclined so that the potential level of the portion overlapping the P-type impurity region is higher than the potential level of the portion not overlapping the P-type impurity region.

  According to the present invention, in the solid-state imaging device, the P-type impurity is preferably boron.

  In the solid-state imaging device according to the present invention, the directing region is an N-type impurity region formed by injecting an N-type impurity into the semiconductor substrate. In the charge transfer channel region, the directing region is provided for each vertical transfer electrode. The potential level is preferably inclined so that the potential level of the portion overlapping with the N-type impurity region is lower than the potential level of the portion not overlapping with the N-type impurity region.

  According to the present invention, in the solid-state imaging device, the N-type impurity is preferably phosphorus or arsenic.

  An electronic information device according to the present invention is an electronic information device including an imaging unit that captures an image of a subject, and the imaging unit is the above-described solid-state imaging device according to the present invention. Is done.

  Next, the operation will be described.

  In the present invention, a solid-state imaging device including a plurality of pixel units and a plurality of vertical transfer units that transfer signal charges generated in the pixel units in the vertical direction, and the pixel units and the vertical transfer units form an imaging region In the device, the vertical transfer unit is formed so as to overlap with the vertical transfer channel region, and has a directing region for tilting the potential level formed in the vertical transfer channel region so that the direction of signal charge transfer is determined, The planar shape of the orientation area is set so that the gradient of the potential level in the plurality of vertical transfer sections becomes gentler as the position of the vertical transfer section is closer to the center of the imaging area. In the vertical transfer unit located at the periphery of the imaging area that changes sharply, the potential level for flowing the signal charge in the transfer direction has a steep slope. So that the load transfer is to follow the rapid change of the signal level of the driving pulse. On the other hand, in the vertical transfer unit located at the center of the imaging region where the signal level of the drive pulse changes gradually, the gradient of the potential level for flowing the signal charge in the transfer direction is gradual, and it is under one vertical transfer electrode. Since the difference between the minimum value and the maximum value of the potential level in the side region (the height of the barrier when the signal charge is transferred) is small, the signal charge is easily moved.

  Thereby, it is possible to suppress the difference in the waveform of the drive pulse of the vertical transfer unit between the central part and the peripheral part of the imaging region of the solid-state imaging device from causing a difference in transfer efficiency and causing an imaging failure.

  In other words, the difference in transfer efficiency due to the rounding of the drive pulse waveform can be absorbed by the potential level profile in the vertical transfer channel region, so that the drive pulse waveform remains rounded in the center of the imaging region. By optimizing the transfer profile of the entire area, the transfer efficiency of the vertical transfer unit can be improved.

  As described above, according to the present invention, a solid-state imaging device capable of effectively improving deterioration of transfer efficiency due to waveform rounding of a drive signal for driving a vertical transfer unit without causing an increase in manufacturing steps, and An electronic information device including such a solid-state imaging device can be realized.

FIG. 1 is a diagram for explaining a CCD solid-state imaging device according to Embodiment 1 of the present invention, and schematically shows the overall configuration of the CCD solid-state imaging device. FIG. 2 is a diagram for explaining the CCD solid-state imaging device according to Embodiment 1 of the present invention, and the arrangement of vertical transfer electrodes and pixel portions in the vertical transfer portion (B portion in FIG. 1) of the CCD solid-state imaging device. Is shown. FIG. 3 is a diagram for explaining the CCD solid-state imaging device according to the first embodiment of the present invention. The vertical transfer electrode, the vertical transfer channel region, and the vertical transfer channel region in the vertical transfer unit (part B in FIG. 1) of the CCD solid-state imaging device. Shows the arrangement. 4A and 4B are diagrams for explaining the CCD solid-state imaging device according to Embodiment 1 of the present invention. FIG. 4A shows a cross-sectional structure taken along the line XX of FIG. 3, and FIG. 3 shows the cross-sectional structure of the YY line portion of FIG. 3, FIG. 4C shows the potential level along the YY line of FIG. 3, and FIG. 4D shows the central portion of the imaging region. The potential level along the vertical transfer direction in the vertical transfer unit is shown, and FIG. 4E shows the potential level along the vertical transfer direction in the vertical transfer unit at the peripheral portion at one end of the imaging region. FIG. 5 is a diagram for explaining the operation of the CCD solid-state imaging device according to the first embodiment of the present invention, in which signal charges are transferred by one vertical transfer unit in the CCD solid-state imaging device (FIG. 5 ( a) to FIG. 5 (c)). FIG. 6 is a diagram for explaining the operation of the CCD solid-state imaging device according to Embodiment 1 of the present invention, and shows the waveforms of the drive pulses of the vertical transfer unit at the center and the peripheral part of the imaging region. FIG. 7 is a diagram for explaining a CCD solid-state imaging device according to Embodiment 2 of the present invention, and schematically shows the overall configuration of the CCD solid-state imaging device. FIG. 8 is a diagram for explaining a CCD solid-state image pickup device according to Embodiment 2 of the present invention. The arrangement of vertical transfer electrodes and pixel portions in a vertical transfer portion (C portion in FIG. 7) of the CCD solid-state image pickup device. Is shown. FIG. 9 is a diagram for explaining a CCD solid-state imaging device according to Embodiment 2 of the present invention. The vertical transfer electrode, the vertical transfer channel region, and the vertical transfer channel region in the vertical transfer section (C portion in FIG. 7) of the CCD solid-state imaging device. Shows the arrangement. 10A and 10B are diagrams illustrating a CCD type solid-state imaging device according to Embodiment 2 of the present invention. FIG. 10A shows a cross-sectional structure taken along line Xa-Xa in FIG. 9, and FIG. 9 shows the cross-sectional structure of the Ya-Ya line portion of FIG. 9, FIG. 10C shows the potential level along the Ya-Ya line of FIG. 9, and FIG. 10D shows the central portion of the imaging region. A potential level along the vertical transfer direction in the vertical transfer unit is shown, and FIG. 10E shows a potential level along the vertical transfer direction in the vertical transfer unit at the peripheral portion at one end of the imaging region. FIG. 11 is a block diagram illustrating a schematic configuration example of an electronic information device using at least one of the solid-state imaging devices of Embodiments 1 and 2 as an imaging unit as Embodiment 3 of the present invention. FIG. 12 is a diagram for explaining a conventional CCD solid-state imaging device disclosed in Patent Document 1, and schematically shows an overall configuration of the CCD solid-state imaging device. FIG. 13 is a diagram for explaining a conventional CCD solid-state image pickup device disclosed in Patent Document 1. The vertical transfer electrode and the pixel portion in the vertical transfer portion (A portion in FIG. 12) of the CCD solid-state image pickup device are described. The arrangement is shown. FIG. 14 is a diagram for explaining a conventional CCD solid-state imaging device disclosed in Patent Document 1, and a vertical transfer electrode and a vertical transfer channel region in a vertical transfer portion (portion A in FIG. 12) of the CCD solid-state imaging device. And shows the arrangement.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
1 to 6 are diagrams for explaining a CCD solid-state imaging device according to Embodiment 1 of the present invention. FIG. 1 schematically shows the overall configuration of the CCD solid-state imaging device, and FIG. FIG. 3 is a diagram for explaining the arrangement of transfer electrodes (vertical transfer electrodes) and pixel portions in a vertical transfer portion (B portion in FIG. 1) of the CCD solid-state image pickup device. FIG. The arrangement of the vertical transfer electrode and the vertical transfer channel region in the portion (B portion in FIG. 1) is shown.

  The CCD solid-state imaging device (hereinafter also simply referred to as a solid-state imaging device) 10 according to the first embodiment includes a plurality of pixel units 11a arranged in a matrix and each column of the plurality of pixel units 11a. A plurality of vertical transfer units 12 that are provided and transfer the signal charges obtained by photoelectric conversion in the pixel unit 11 a in the vertical direction, and are arranged on one end side of these vertical transfer units 12. The horizontal transfer unit 13 that horizontally transfers the signal charge transferred from the horizontal transfer unit 13 and the output unit 14 that converts the signal charge transferred from the horizontal transfer unit 13 into a voltage signal, amplifies and outputs the voltage signal. . Here, the pixel unit 11a and the vertical transfer unit 12 constitute an imaging region 11b, and the pixel unit 11a includes a photoelectric conversion element such as a photodiode as a light receiving unit. Each vertical transfer unit 12 is driven by four-phase drive signals ΦV1 to ΦV4. In the imaging region 11b, the green color filter G, the blue color filter B, and the red color filter R are in a Bayer array.

  Further, as shown in FIG. 3, the imaging region 11b includes vertical transfer electrodes (transfer gates) 12a to 12a along the vertical transfer channel region 120 constituting the vertical transfer units 121 to 125 (vertical transfer unit 12 in FIG. 1). 12d is arranged. These vertical transfer electrodes 12a to 12d are made of a conductive film formed on a semiconductor substrate via an insulating film. Here, the conductive film constituting the vertical transfer electrode is formed of, for example, a polysilicon film containing conductive impurities. However, the configuration of the vertical transfer electrode is not limited to this.

  Hereinafter, the configuration of the vertical transfer units 121 to 125 (vertical transfer unit 12 in FIG. 1) will be described in detail with reference to FIGS.

  As shown in FIGS. 2 and 3, the planar shape of the vertical transfer electrodes 12a to 12d extends in a direction (horizontal direction) intersecting the vertical transfer channel region 120 so as not to overlap the pixel portion 11a across the imaging region 11b. It has a shape. The voltages of the four-phase drive signals φV1 to φV4 are applied from the bus lines Bs1 to Bs4 to both ends of the vertical transfer electrodes 12a to 12d extending to the outside of the imaging region 11b. .

  In FIG. 3, the vertical transfer unit 12 illustrated in FIG. 1 is illustrated as the vertical transfer units 121 to 125 according to the positions in the imaging region. That is, in FIG. 3, as one part of the vertical transfer unit 12 (B portion in FIG. 1) of the CCD solid-state imaging device, one of the two adjacent vertical transfer units 123 and the image pickup region 11b in the central part B3 of the image pickup region 11b One vertical transfer part 121 in the side part (peripheral part) B1 of this image, one vertical transfer part 125 in the other side part (peripheral part) B5 of the imaging region 11b, the central part B3 and one side part B1 of the imaging region 11b. Two adjacent vertical transfer units 122 in the part B2 between the two and the two adjacent vertical transfer units 124 in the part B4 between the central part B3 and the other side part B5 of the imaging region 11b are shown. In FIG. 3, the bus lines Bs1 to Bs4 shown in FIG. 2 are omitted.

  Next, the cross-sectional structure of the vertical transfer unit will be described with reference to FIG. 4 taking the vertical transfer unit 124 as an example.

  4A shows the cross-sectional structure of the XX line portion of FIG. 3, FIG. 4B shows the cross-sectional structure of the YY line portion of FIG. 3, and FIG. 3 shows the potential level along the Y-Y line, FIG. 4D shows the potential level along the vertical transfer direction in the vertical transfer unit in the center of the imaging region, and FIG. The potential level is shown along the vertical transfer direction in the vertical transfer portion at the peripheral portion at one end of the imaging region.

As shown in FIGS. 4A and 4B, the surface portion of the P-type well region 101a formed on the surface portion of the N-type semiconductor substrate (for example, N-type silicon substrate) 101 is the vertical transfer channel region 120. In addition, an N-type impurity region is formed, and a P-type impurity region R4 is formed as an orientation region for tilting the potential level formed in the vertical transfer channel region so that the direction of signal charge transfer is determined. . Here, the P-type impurity region R4 is formed by introducing a P-type dopant such as boron (B) or boron fluoride (BF ₂ ), and the N-type impurity region is P (phosphorus) or arsenic (As). ) Or the like.

Here, the impurity concentration of the N-type semiconductor substrate is 10 ¹² to 10 ¹⁶ / cm ³ , and the impurity concentration of the P-type well region 101 a is 10 ¹² to 10 ¹⁶ / cm ³ , and the vertical transfer channel The impurity concentration of the N-type impurity region as the region 120 is 10 ¹⁵ to 10 ¹⁹ / cm ³ , and the impurity concentration of the P-type impurity region as the directing region R4 is 10 ¹⁴ to 10 ¹⁸ / cm ³ .

  As a result, the potential level Lp formed in the portion of the vertical transfer channel region 120 of the vertical transfer portion 124 facing the vertical transfer electrodes 12a to 12d forms the orientation region R4 as shown in FIG. 4C. The portion that has been tilted so as to be higher than the portion where the orientation region R4 is not formed, and the direction Vd of charge transfer is defined by the orientation region R4.

  In FIG. 4C, the drive pulse ΦV1 to ΦV4 applied to the vertical transfer electrodes 12a to 12d causes the potential level on the lower side of the vertical transfer electrodes 12b to 12d to be lower on the lower side of the vertical transfer electrode 12a. It shows a state that is deeper than the potential level.

  Further, the orientation region is formed as P-type impurity regions R1 to R3 and R5 not only in the vertical charge transfer unit 124 but also in the vertical transfer channel regions 120 of the other vertical charge transfer units 121 to 123 and 125. The impurity concentrations of the P-type impurity regions R1 to R3 and R5 as these directing regions are the same as the impurity concentration of the P-type impurity region R4.

  In the first embodiment, the planar shape of the orientation regions R1 to R5 formed in the vertical transfer channel region 120 of the vertical charge transfer units 121 to 125 is such that the gradient of the potential level in the plurality of vertical transfer units is vertical. The position of the transfer unit is set so as to be gentler as it is closer to the central part B3 of the imaging region 11b.

  That is, here, the orientation areas R1 and R5 located in the side parts (peripheral parts) B1 and B5 of the imaging area 11b are vertical transfer channels compared to the orientation area R3 located in the central part B3 of the imaging area 11b. An area overlapping the region 120 is formed to be large, and an orientation region R2 located in a portion B2 between the central portion B3 and the side portion B1 of the imaging region 11b overlaps with the vertical transfer channel region 120. Is formed to be larger than the area where the directing region R3 and the vertical transfer channel region 120 overlap, and to be smaller than the area where the directing regions R1 and R5 and the vertical transfer channel region 120 overlap. In the directing region R4 located in the portion B4 between the central portion B3 and the side portion B5 of 11b, the area overlapping the vertical transfer channel region 120 is directed. Is formed as a region R3 become large compared to the area that overlaps the vertical transfer channel region 120, and directing region R1, R5 and the vertical transfer channel region 120 and so that is smaller than the area that overlaps.

  In this way, by changing the area where the directing region and the vertical transfer channel region overlap with each other according to the position of the vertical transfer unit in the imaging region 11b, it is formed in the vertical transfer channel region depending on the position of the vertical transfer unit in the imaging region 11b. The magnitude of the potential level gradient can be changed.

  For example, in the vertical transfer unit 121 (FIG. 4E) located on the side B1 of the imaging region 11b, the area where the orientation region R1 and the vertical transfer channel region 120 overlap is large, while the central portion of the imaging region 11b. In the vertical transfer unit 123 (FIG. 4D) located at B3, the area where the directing region R3 and the vertical transfer channel region 120 overlap is small, and therefore, the vertical transfer unit located at the side B1 of the imaging region 11b. The inclination of the potential level Lp1 formed in the vertical transfer channel region 120 of 121 (FIG. 4E) is the vertical transfer channel of the vertical transfer unit 123 (FIG. 4D) located at the central portion B3 of the imaging region 11b. It is larger than the gradient of the potential level Lp2 formed in the region 120.

  As a result, it is possible to eliminate the deterioration of the transfer characteristics due to the difference in the waveform of the drive pulse of the vertical transfer electrode between the central portion and the peripheral portion of the imaging region.

  Here, the planar shape of each of the directing regions R1 to R5 is a right triangle shape, and one of two sides other than the oblique sides is arranged so as to cross the vertical transfer channel region 120 perpendicular to the vertical transfer direction. The other of the two sides other than the oblique side is arranged in parallel with the vertical transfer direction, and the length of the side parallel to the vertical transfer direction is constant in any of the vertical transfer channel regions ( For example, the area of the overlapping portion between the directing region and the vertical transfer electrode is the length of the side perpendicular to the vertical transfer direction of the directing region (for example, in the range of 0.1 μm to 1.0 μm). ) To adjust the shape.

  Further, the directing regions R1 to R5 in all the vertical transfer portions in the imaging region 11b can be formed by a single ion implantation process.

  That is, since the orientation regions R1 to R5 differ only in the planar shape for each vertical transfer portion in the imaging region 11b, an ion implantation mask for forming the impurity region as the orientation region is used as the mask opening. The area can be easily formed by matching the shape of the area with the plane pattern of the orientation area to be formed in each vertical transfer section.

  2 and 3, only the portion of the vertical transfer electrode corresponding to the five regions B1 to B5 in the imaging region 11b is shown. However, the vertical transfer electrode extends from one side to the other side of the imaging region 11b. Needless to say, it has a shape extending toward the top and is formed across all vertical transfer channel regions in the imaging region 11b.

  In FIG. 3, the planar shape of the directing regions R2 to R4 is the same in two adjacent vertical transfer units, but the planar shape of the directing region may be changed for each vertical transfer unit or 3 Two or more vertical transfer units may be changed as one set. However, it is desirable that the number of vertical transfer units belonging to one set having the same planar shape of the directing area be smaller.

  Here, the drive signal for driving the vertical transfer unit is a four-phase drive pulse, but a drive pulse of four or more phases such as an eight-phase drive pulse may be used.

  In addition, the planar shape of the orientation region is not limited to the right triangle shape shown in FIG. 3, but may be, for example, a rectangular shape. In this case, a long side perpendicular to the vertical transfer direction of the rectangular shape has a certain length. Then, the length of the short side is changed according to the position of the vertical transfer unit in the imaging region, so that the area of the overlapping portion between the directing region and the vertical transfer channel region is changed.

  Further, the directing region is not limited to the one constituted by the P-type impurity region, and may be constituted by the N-type impurity region. However, in the case where the directing region is formed of an N-type impurity region, the potential level is deeper in the portion where the directing region is formed in the vertical transfer channel region than in the portion where the directing region is not formed. When the signal charge is transferred in the same direction as the case where the directing region is formed by the P-type impurity region, the orientation region is arranged with respect to the vertical transfer electrode shown in FIG. It is necessary that the right triangle be folded around the hypotenuse.

  Next, the operation will be described.

  In such a solid-state imaging device, when a drive signal is supplied to each of the vertical transfer unit 12 and the horizontal transfer unit 13, the signal charge generated by the pixel unit 11 a is read to the vertical transfer unit 12 and further transferred vertically. In the unit 12, the signal charge is transferred in the vertical direction and sent to the horizontal transfer unit 13.

  The horizontal transfer unit 13 transfers the signal charge from the vertical transfer unit 12 in the horizontal direction, and the output unit 14 converts the signal charge from the horizontal transfer unit 13 into a signal voltage, which is amplified and output.

  Hereinafter, the operation of the vertical transfer unit 12 according to the first embodiment will be described in detail.

  FIG. 5 is a diagram for explaining the operation of the CCD solid-state imaging device according to the first embodiment of the present invention, in which signal charges are transferred by one vertical transfer unit in the CCD solid-state imaging device (FIG. 5 ( a) to FIG. 5 (c)).

  For example, at the timing (t = t1) shown in FIG. 5A, the drive pulse ΦV1 of the vertical transfer electrode 12a is at the low level, and the drive pulses ΦV2 to ΦV4 of the vertical transfer electrodes 12b to 12d are at the middle level. The potential level below the vertical transfer electrodes 12b to 12d in the vertical transfer channel region 120 is lower than the potential level below the vertical transfer electrode 12a in the vertical transfer channel region 120, and this potential level is low. The signal charge Sc1 is accumulated in the portion.

  Next, at the timing (t = t2) shown in FIG. 5B, the drive pulses ΦV1 and ΦV2 of the vertical transfer electrodes 12a and 12b are inverted, so that the lower side of the vertical transfer electrode 12b in the vertical transfer channel region 120 The signal charge Sc1 in the portion moves along the vertical transfer direction Vd, and the signal charge Sc2 moves from the upstream side of the vertical transfer channel region to the lower portion of the vertical transfer electrode 12a in the vertical transfer channel region 120. .

  Further, at the timing (t = t3) shown in FIG. 5 (c), the drive pulses ΦV2 and ΦV3 of the vertical transfer electrodes 12b and 12c are inverted, whereby the lower portion of the vertical transfer electrode 12c in the vertical transfer channel region 120 The signal charge Sc1 moves along the vertical transfer direction Vd, and the signal charge Sc2 moves from the upstream side of the vertical transfer channel region to the lower portion of the vertical transfer electrode 12b of the vertical transfer channel region 120.

  In this manner, the vertical transfer unit 12 is driven by the four-phase drive pulses ΦV1 to ΦV4, and the signal charges are transferred in the vertical transfer unit 12 along the vertical transfer direction Vd.

  Incidentally, also in the first embodiment, as shown in FIG. 2, the vertical transfer electrodes 12a to 12d are configured such that the drive pulses ΦV1 to ΦV4 are applied to both ends via the bus lines Bs1 to Bs4, respectively. For this reason, the waveform of the drive pulse applied to the vertical transfer electrode is different depending on the transmission delay in the central portion B3 and the peripheral portions B1 and B5 of the imaging region 11b.

  FIG. 6 shows the waveform La of the driving pulse in the vertical transfer units 121 and 125 located in the peripheral parts B1 and B5 of the imaging region, and the waveform Lb of the driving pulse in the vertical transfer unit 123 located in the central part B3 of the imaging region. It is shown in contrast with.

  As shown in FIG. 6, in the central portion B3 of the imaging region, the waveform of the drive pulse applied to the vertical transfer unit 123 becomes more gradual than the peripheral portions B1 and B5 of the imaging region. However, in the solid-state imaging device according to the first embodiment, the planar shape of the orientation region is changed to the peripheral portion B1 and B5 of the imaging region at the central portion B3 of the imaging region, thereby being positioned on the side portion B1 of the imaging region 11b. The inclination of the potential level Lp1 formed in the vertical transfer channel region 120 of the vertical transfer unit 121 (FIG. 4E) is the same as that of the vertical transfer unit 123 (FIG. 4D) positioned at the center B3 of the imaging region 11b. It is larger than the gradient of the potential level Lp2 formed in the vertical transfer channel region 120.

  Therefore, in the vertical transfer units 121 and 125 located in the peripheral portions B1 and B5 of the imaging region 11b where the signal level of the drive pulse changes sharply, the potential level Lp1 for flowing the signal charge in the transfer direction has a steep slope. Therefore, the transfer of the signal charge follows a steep change in the signal level of the drive pulse, and the charge can be transferred to the next vertical transfer electrode in a short period.

  On the other hand, in the vertical transfer unit 123 located in the central portion B3 of the imaging region 11b where the signal level of the drive pulse changes gradually, the gradient of the potential level Lp2 for flowing the signal charge in the transfer direction is gentle, and one vertical Since the difference H2 between the minimum value and the maximum value of the potential level in the lower region of the transfer electrode (the height of the barrier when transferring signal charges) H2 is small, the barrier H2 of the next vertical transfer electrode 12d is exceeded. The signal charge easily moves from the vertical transfer electrode 12c to the vertical transfer electrode 12d. In FIG. 4E, H1 is the difference between the minimum value and the maximum value of the potential level in the lower region of one vertical transfer electrode in the vertical transfer unit 121 located in the peripheral portion B1 of the imaging region 11b. (The height of the barrier when the signal charge is transferred).

  As described above, the first embodiment includes a plurality of pixel units and a plurality of vertical transfer units that transfer signal charges generated in the pixel units in the vertical direction, and the pixel unit and the vertical transfer unit form an imaging region. In the solid-state imaging device 10, each of the vertical transfer units 121 to 125 is formed so as to overlap with the vertical transfer channel region, and the potential level formed in the vertical transfer channel region is inclined so that the direction of signal charge transfer is determined. The orientation areas R1 to R5 have a planar shape such that the inclination of the potential level in the plurality of vertical transfer units becomes gentler as the position of the vertical transfer units is closer to the center of the imaging region 11b. Since it is set, the vertical transfer units 121 and 125 located in the peripheral portions B1 and B5 of the imaging region 11b where the signal level of the drive pulse changes sharply. Since the slope of the potential level Lp1 for supplying a signal charge transfer direction is steep, so that the transfer of signal charges to follow the steep change in the signal level of the driving pulse. On the other hand, in the vertical transfer unit 123 located in the central portion B3 of the imaging region 11b where the signal level of the drive pulse changes gradually, the gradient of the potential level Lp2 for flowing the signal charge in the transfer direction is gentle, and one vertical Since the difference H2 between the minimum value and the maximum value of the potential level in the lower region of the transfer electrode (the height of the barrier when transferring the signal charge) H2 is small, the signal charge easily moves.

  Thereby, it is possible to suppress the difference in the waveform of the drive pulse of the vertical transfer unit between the central part and the peripheral part of the imaging region of the solid-state imaging device from causing a difference in transfer efficiency and causing an imaging failure.

  That is, the difference in transfer efficiency due to waveform rounding of the drive pulse can be absorbed by the profile of the potential level in the vertical transfer channel region 120, so that the waveform rounding of the drive pulse remains in the center of the imaging region, By optimizing the transfer profile of the entire imaging area, the transfer efficiency of the vertical transfer unit can be improved.

  In the first embodiment, as the solid-state imaging device, the vertical transfer electrode is formed of, for example, a polysilicon film containing conductive impurities. However, in the solid-state imaging device, the vertical transfer electrode is a metal film. It may be composed of wiring and a polysilicon film. Even in the solid-state imaging device in which the vertical transfer electrode is formed of the metal wiring and the polysilicon film as described above, if the pixel size is small, the line width of the metal wiring becomes narrow, so that the resistance value increases and the central portion of the imaging region Then, rounding of the waveform of the drive pulse occurs. For this reason, in this case as well, the difference in transfer efficiency due to waveform rounding of the drive pulse between the central portion and the peripheral portion of the imaging region described in the first embodiment is expressed as a potential level profile in the vertical transfer channel region. The structure which absorbs by this becomes effective.

Therefore, in a second embodiment below, a solid-state imaging device including the vertical transfer electrode having such a configuration will be specifically described.
(Embodiment 2)
7 to 10 are diagrams for explaining a CCD solid-state imaging device according to Embodiment 2 of the present invention. FIG. 7 schematically shows the overall configuration of the CCD solid-state imaging device, and FIG. FIG. 9 is a diagram for explaining the arrangement of transfer electrodes (vertical transfer electrodes) and pixel portions in a vertical transfer portion (C portion in FIG. 7) of the CCD solid-state image pickup device. FIG. 8 shows the arrangement of vertical transfer electrodes and vertical transfer channel regions in the portion (C portion in FIG. 7).

  In the solid-state imaging device 20 of the second embodiment, instead of the vertical transfer electrodes 12a to 12d made of a polysilicon film in the solid-state imaging device 10 of the first embodiment, the unit transfer electrode 202 made of a polysilicon film is made of a metal wiring. The vertical transfer electrodes 22a to 22d having a structure connected to the transfer wiring 201 are provided, and other configurations are the same as those in the first embodiment. That is, the solid-state imaging device 20 has been transferred from the plurality of pixel units 11 a, the plurality of vertical transfer units 22 that transfer the signal charges obtained by photoelectric conversion in the pixel unit 11 a in the vertical direction, and the vertical transfer unit 22. A horizontal transfer unit 13 for transferring the signal charge in the horizontal direction, and an output unit 14 for converting the signal charge transferred from the horizontal transfer unit 13 into a voltage signal, amplifying and outputting the voltage signal.

  Here, the unit transfer electrode 202 constituting the vertical transfer electrodes 22a to 22d is made of a polysilicon film formed on the semiconductor substrate via an insulating film, and the transfer wiring constituting the vertical transfer electrodes 22a to 22d. 201 is made of a metal material film formed on the polysilicon film through an interlayer insulating film, and has a shape extending from one side to the other side of the imaging region 11b. The voltages of the four-phase drive signals φV1 to φV4 are applied to both ends extending to the outside of the imaging region 11b from the bus lines Bs1 to Bs4.

  Hereinafter, the vertical transfer unit and the vertical transfer electrode of the solid-state imaging device 20 of Embodiment 2 will be described in detail.

  Here, the configuration of the vertical transfer unit and the vertical transfer electrode in the solid-state imaging device according to the second embodiment will be described with reference to FIGS. 8 and 9 showing details of the portion C of the solid-state imaging device 20 shown in FIG.

  In FIG. 9, the vertical transfer unit 22 illustrated in FIG. 7 is illustrated as the vertical transfer units 221 to 225 depending on the position in the imaging region. That is, in FIG. 9, as one part of the vertical transfer unit 22 (C portion in FIG. 7) of the CCD type solid-state image pickup device, one of the two adjacent vertical transfer units 223 and the image pickup region 11b in the central part C3 of the image pickup region 11b. One vertical transfer part 221 in the side part (peripheral part) C1 of this image, one vertical transfer part 225 in the other side part (peripheral part) C5 of the imaging region 11b, the central part C3 and one side part C1 of the imaging region 11b. Two adjacent vertical transfer units 222 in the portion C2 between the two, and two adjacent vertical transfer units 224 in the portion C4 between the center portion C3 and the other side portion C5 of the imaging region 11b are shown. In FIG. 9, the bus lines Bs1 to Bs4 shown in FIG. 8 are omitted.

  A plurality of unit transfer electrodes 202 are arranged along the vertical transfer direction on the vertical transfer channel region 220 of each of the vertical transfer units 221 to 225, and in the matrix formed by the unit transfer electrodes 202 of all the vertical transfer units. A transfer wiring 201 is provided for each row.

  For example, in the portion C of the solid-state imaging device 20 shown in FIG. 7, as shown in FIG. 8, the transfer wiring 201 is provided along the column of the unit transfer electrodes 202 in the first row from the paper surface. 201 and the corresponding unit transfer electrode 202 are connected by the contact part 203, and the vertical transfer electrode 22a is formed. Similarly, the unit transfer electrode 202 in the second row from the page of FIG. 8 and the transfer wiring 201 arranged along the column of the unit transfer electrode 202 in the second row are connected by the contact portion 203 to be vertically transferred. The electrode 22b is formed, and the unit transfer electrode 202 in the third row from the paper surface of FIG. 8 is connected to the transfer wiring 201 arranged along the column of the unit transfer electrode 202 in the third row by the contact portion 203. The vertical transfer electrode 22c is formed, and the unit transfer electrode 202 in the fourth row from the plane of FIG. 8 and the transfer wiring 201 arranged along the column of the unit transfer electrode 202 in the fourth row are in contact with each other. The vertical transfer electrodes 22d are formed by being connected by the portion 203.

  Next, the cross-sectional structure of the vertical transfer unit will be described with reference to FIG. 10, taking the vertical transfer unit 224 as an example.

  10A shows the cross-sectional structure of the Xa-Xa line portion of FIG. 9, FIG. 10B shows the cross-sectional structure of the Ya-Ya line portion of FIG. 9, and FIG. 9 shows the potential level along the Ya-Ya line, FIG. 10D shows the potential level along the vertical transfer direction in the vertical transfer unit at the center of the imaging region, and FIG. The potential level is shown along the vertical transfer direction in the vertical transfer portion at the peripheral portion at one end of the imaging region.

As shown in FIGS. 10A and 10B, the surface portion of the P-type well region 101a formed on the surface portion of the N-type semiconductor substrate (for example, N-type silicon substrate) 101 has a vertical transfer channel region 220. In addition, an N-type impurity region is formed, and a P-type impurity region R4 is formed as an orientation region for tilting the potential level formed in the vertical transfer channel region so that the direction of signal charge transfer is determined. . Here, the P-type impurity region R4 is formed by introducing a P-type dopant such as boron (B) or boron fluoride (BF ₂ ), and the N-type impurity region is P (phosphorus) or arsenic (As). ) Or the like.

  The impurity concentration of the N-type semiconductor substrate, the impurity concentration of the P-type well region 101a, the impurity concentration of the N-type impurity region as the vertical transfer channel region 220, and the impurity concentration of the P-type impurity region as the directing region R4 are 1 is the same as in 1.

  As a result, the potential level Lp formed at the portion of the vertical transfer channel region 220 of the vertical transfer unit 224 facing the unit transfer electrode 202 of each of the vertical transfer electrodes 22a to 22d is as shown in FIG. The portion where the orientation region R4 is formed is inclined to be higher than the portion where the orientation region R4 is not formed, and the charge transfer direction Vd is defined by the orientation region R4.

  In FIG. 10C, the drive pulses ΦV1 to ΦV4 applied to the vertical transfer electrodes 22a to 22d cause the potential level below the unit transfer electrode 202 of the vertical transfer electrodes 22b to 22d to be lower than that of the vertical transfer electrode 22a. A state in which the level is deeper than the potential level below the unit transfer electrode 202 is shown.

  Further, the orientation region is formed as P-type impurity regions R1 to R3 and R5 not only in the vertical transfer unit 124 but also in the vertical transfer channel regions 220 of the other vertical transfer units 221 to 223 and 225. The impurity concentrations of the P-type impurity regions R1 to R3 and R5 as these directing regions are the same as the impurity concentration of the P-type impurity region R4.

  In the second embodiment, the planar shapes of the orientation regions R1 to R5 formed in the vertical transfer channel region 220 of the vertical charge transfer units 221 to 225 are similar to those in the first embodiment in the plurality of vertical transfer units. The inclination of the potential level is set so as to be gentler as the position of the vertical transfer portion is closer to the central portion C3 of the imaging region 11b.

  That is, here, the orientation areas R1 and R5 located in the side portions (peripheral parts) C1 and C5 of the imaging area 11b are vertical transfer channels compared to the orientation area R3 located in the center part C3 of the imaging area 11b. An area overlapping the region 220 is formed to be large, and the orientation region R2 located in the portion C2 between the central portion C3 and the side portion C1 of the imaging region 11b overlaps the vertical transfer channel region 220. Is formed so as to be larger than the orientation region R3 and smaller than the orientation regions R1 and R5, and is located at the portion C4 between the central portion C3 and the side portion C5 of the imaging region 11b. In the region R4, the area overlapping the vertical transfer channel region 220 is larger than the area overlapping the directing region R3 and the vertical transfer channel region 220, and the region R4 is oriented. And it is formed to be smaller than the area where the frequency R1, R5 and the vertical transfer channel region 220 overlaps.

  In this way, by changing the area where the directing region and the vertical transfer channel region overlap with each other according to the position of the vertical transfer unit in the imaging region 11b, it is formed in the vertical transfer channel region depending on the position of the vertical transfer unit in the imaging region 11b. The magnitude of the potential level gradient can be changed.

  For example, in the vertical transfer unit 221 (FIG. 10E) located on the side C1 of the imaging region 11b, the area where the orientation region R1 and the vertical transfer channel region 220 overlap is large, while the central portion of the imaging region 11b. In the vertical transfer unit 223 located in C3 (FIG. 10D), the area where the directing region R3 and the vertical transfer channel region 220 overlap is small, and therefore the vertical transfer unit located in the side C1 of the imaging region 11b. The inclination of the potential level Lp1 formed in the vertical transfer channel region 220 of 221 (FIG. 10 (e)) is the vertical transfer channel of the vertical transfer unit 223 (FIG. 10 (d)) located at the center C3 of the imaging region 11b. It is larger than the gradient of the potential level Lp2 formed in the region 220.

  Thereby, it is possible to eliminate the deterioration of transfer characteristics due to the difference in the waveform of the drive pulse of the vertical transfer electrode between the central portion and the peripheral portion of the imaging region.

  8 and 9, only the portions of the vertical transfer electrodes 22a to 22d corresponding to the five regions C1 to C5 in the imaging region 11b are shown, but the transfer wiring 201 that constitutes these vertical transfer electrodes is shown in FIG. Needless to say, it has a shape extending from one side of the imaging region toward the other side and is formed across all the vertical transfer channel regions in the imaging region 11b.

  Also in the solid-state imaging device 20 having such a configuration, by supplying drive signals to the vertical transfer unit 22 and the horizontal transfer unit 13, signal charges generated in the pixel unit 11 a are read out to the vertical transfer unit 22. Further, in the vertical transfer unit 22, the signal charges are transferred in the vertical direction and sent to the horizontal transfer unit 13. In the horizontal transfer unit 13, the signal charge from the vertical transfer unit 22 is transferred in the horizontal direction, and in the output unit 14, the signal charge from the horizontal transfer unit 13 is converted into a signal voltage, amplified, and output.

  The second embodiment having such a configuration includes a plurality of pixel units 11a and a plurality of vertical transfer units that transfer signal charges generated in the pixel units in the vertical direction. In the solid-state imaging device 20 forming 11b, the vertical transfer units 121 to 125 are formed so as to overlap with the vertical transfer channel region 220, and the potential level formed in the vertical transfer channel region is set to transfer signal charges. The orientation areas R1 to R5 are inclined so as to determine the direction, and the planar shape of the orientation area is such that the potential level in the plurality of vertical transfer portions is inclined, and the position of the vertical transfer portions is close to the central portion C3 of the imaging region. Since it is set so that the signal level of the drive pulse changes steeply, the vertical shift located in the peripheral portions C1 and C5 of the imaging region 11b where the signal level of the drive pulse changes sharply. In parts 221 and 225, a potential level of the slope steep for supplying a signal charge transfer direction, Therefore, so that the transfer of signal charges to follow the steep change in the signal level of the driving pulse. On the other hand, in the vertical transfer unit 223 located in the central portion C3 of the imaging region 11b where the signal level of the drive pulse changes gradually, the potential level for flowing the signal charge in the transfer direction has a gentle slope, and therefore one The difference between the minimum value and the maximum value of the potential level in the lower region of the vertical transfer electrode (the height of the barrier when transferring the signal charge) is small, and the signal charge is easy to move.

  Thereby, it is possible to suppress the difference in the waveform of the drive pulse of the vertical transfer unit between the central part and the peripheral part of the imaging region of the solid-state imaging device from causing a difference in transfer efficiency and causing an imaging failure.

  In other words, the difference in transfer efficiency due to waveform rounding of the drive pulse signal can be absorbed by the profile of the potential level in the vertical transfer channel region, so that the waveform rounding of the drive pulse remains occurring in the center of the imaging region, By optimizing the transfer profile of the entire imaging area, the transfer efficiency of the vertical transfer unit can be improved.

  In the second embodiment, the vertical transfer electrode is formed of a metal that extends in the horizontal direction so that the unit transfer electrode 201 made of a polysilicon film is formed on the vertical transfer channel region constituting each vertical transfer unit and straddles the plurality of vertical transfer units. Since the structure is connected to the wiring 202 through the contact portion 203, the vertical transfer electrode is reduced in resistance to suppress the rounding of the drive pulse waveform of the vertical transfer portion, and the difference in transfer efficiency due to the rounding of the waveform of the drive pulse signal is reduced. Absorption can be achieved by the profile of the potential level in the transfer channel region, whereby the transfer efficiency of the vertical transfer unit can be further improved.

Furthermore, although not specifically described in the first and second embodiments, a digital camera such as a digital video camera or a digital still camera using at least one of the solid-state imaging devices of the first and second embodiments as an imaging unit. An electronic information device having an image input device, such as an image input camera, a scanner, a facsimile machine, or a camera-equipped mobile phone, will be briefly described below.
(Embodiment 3)
FIG. 11 is a block diagram illustrating a schematic configuration example of an electronic information device using at least one of the solid-state imaging devices of Embodiments 1 and 2 as an imaging unit as Embodiment 3 of the present invention.

  An electronic information device 90 according to Embodiment 2 of the present invention shown in FIG. 11 includes at least one of the solid-state imaging devices according to Embodiments 1 and 2 of the present invention as an imaging unit 91 that captures a subject. A memory unit 92 such as a recording medium for recording data after high-definition image data obtained by photographing by such an image pickup unit is subjected to predetermined signal processing for recording, and predetermined signal processing for displaying the image data A display unit 93 such as a liquid crystal display device that displays on a display screen such as a liquid crystal display screen, and a communication unit 94 such as a transmission / reception device that performs communication processing after performing predetermined signal processing on the image data for communication. And an image output unit 95 that prints (prints) image data and outputs (prints out) the image data.

  As mentioned above, although this invention has been illustrated using preferable embodiment of this invention, this invention should not be limited and limited to this embodiment. It is understood that the scope of the present invention should be construed only by the claims. It is understood that those skilled in the art can implement an equivalent range based on the description of the present invention and the common general technical knowledge from the description of specific preferred embodiments of the present invention. Patents, patent applications, and documents cited herein should be incorporated by reference in their entirety, as if the contents themselves were specifically described herein. Understood.

  In the field of solid-state imaging devices and electronic information devices, the present invention can effectively improve deterioration in transfer efficiency due to waveform rounding of a drive signal that drives a vertical transfer unit without causing an increase in manufacturing steps. An imaging apparatus and an electronic information device including such a solid-state imaging apparatus can be realized.

10 CCD type solid-state imaging device (solid-state imaging device)
11a Pixel unit 11b Imaging region 12, 20, 121-124, 221-224 Vertical transfer unit 12a-12d, 22a-22d Vertical transfer electrode 13 Horizontal transfer unit 14 Output unit 90 Electronic information device 91 Imaging unit 92 Memory unit 93 Display unit 94 Communication portion 95 Image output portion 120, 220 Vertical transfer channel region 201 Transfer wiring 202 Unit transfer electrode 203 Contact portion B1 and B5 Peripheral portion (side portion)
Part between B2 and B4 B3 Central part Bs1 to Bs4 Bus line H1, H2 Barrier height La, Lb Drive pulse waveform Lp, Lp1, Lp2 Potential level R1 to R5 Orientation region Sc1, Sc2 Signal charge Vd Vertical transfer direction ΦV1 ~ ΦV4 drive signal

Claims (10)

A plurality of pixel units arranged in a matrix and generating signal charges by photoelectric conversion of incident light, and the signal charges generated by the pixel units of the corresponding columns are provided in each column of the plurality of pixel units in the vertical direction. A solid-state imaging device comprising a plurality of vertical transfer units that transfer to the pixel unit, wherein the pixel unit and the vertical transfer unit form an imaging region,
The vertical transfer unit
A vertical transfer channel region formed on the semiconductor substrate as the signal charge transfer path along the vertical direction;
An orientation region formed on the semiconductor substrate so as to overlap the vertical transfer channel region, and inclining a potential level formed in the vertical transfer channel region so as to determine a transfer direction of the signal charge;
The planar shape of the directing region is set so that the inclination of the potential level in the plurality of vertical transfer units becomes gentler as the position of the vertical transfer unit is closer to the center of the imaging region. apparatus. The solid-state imaging device according to claim 1,
A plurality of vertical transfer electrodes arranged along the vertical direction on the imaging region;
Each of the plurality of vertical transfer electrodes is
A solid-state imaging device formed across each vertical transfer channel region so as to straddle the plurality of vertical transfer channel regions. The solid-state imaging device according to claim 1,
A plurality of unit transfer electrodes arranged on a vertical transfer channel region of each of the plurality of vertical transfer units;
A plurality of transfer lines formed across each vertical transfer channel region so as to straddle the plurality of vertical transfer channel regions,
A solid-state imaging device, wherein the transfer wiring is connected to the unit transfer electrode facing the transfer wiring by a contact portion to form a plurality of vertical transfer electrodes. The solid-state imaging device according to claim 3,
The unit transfer electrode is made of a polysilicon film,
The transfer wiring is a solid-state imaging device, which is a metal wiring made of a metal material. The solid-state imaging device according to any one of claims 2 to 4,
The solid-state imaging device, wherein the directing region is formed in a portion facing each of the plurality of vertical transfer electrodes in the vertical transfer channel region. In the solid-state imaging device according to any one of claims 1 to 5,
The directing region is a P-type impurity region formed by injecting a P-type impurity into the semiconductor substrate,
In the charge transfer channel region,
A solid-state imaging device, wherein a potential level of each vertical transfer electrode is inclined so that a potential level of a portion overlapping with the P-type impurity region is higher than a potential level of a portion not overlapping with the P-type impurity region. The solid-state imaging device according to claim 6,
The solid-state imaging device, wherein the P-type impurity is boron. In the solid-state imaging device according to any one of claims 1 to 5,
The directing region is an N-type impurity region formed by injecting an N-type impurity into the semiconductor substrate,
In the charge transfer channel region,
A solid-state imaging device, wherein a potential level of each vertical transfer electrode is inclined so that a potential level of a portion overlapping with the N-type impurity region is lower than a potential level of a portion not overlapping with the N-type impurity region. The solid-state imaging device according to claim 8,
The solid-state imaging device, wherein the N-type impurity is phosphorus or arsenic. An electronic information device having an imaging unit for imaging a subject,
The electronic information device, wherein the imaging unit is a solid-state imaging device according to any one of claims 1 to 9.

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