JP2004088044A - Solid-state-image pickup device and its drive method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily meet the requirement for micro-miniaturization of a pixel size. <P>SOLUTION: The solid-state-image pickup device is provided with a photoelectric converter 14 to generate signal charges according to the incident light amount, a charge transfer 12 to transfer the signal charges received from the photoelectric converter 14, and a read gate 13 to read the signal charges between the photoelectric converter 14 and the charge transfer 12. A read electrode 2, to which a voltage to make the read gate 13 read is impressed, is independently formed separately from a transfer electrode 1 to which a voltage to make the charge transfer 12 transfer the signal charges is impressed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a solid-state imaging device such as a charge coupled device (CCD) image sensor and a driving method thereof.
[0002]
[Prior art]
Conventionally, as a solid-state imaging device, a CCD image sensor whose imaging area is configured as shown in FIG. 3 is widely known. In the illustrated imaging area, a channel stop unit 11, a vertical transfer unit 12, a readout gate unit 13, and a photo sensor unit 14 are arranged horizontally on a substrate (such as a silicon substrate), and a photo sensor in the vertical direction is provided. The portions 14 are separated from each other by a pixel separating portion 15, whereby a plurality of photosensor portions 14 are arranged in a two-dimensional matrix. Above the vertical transfer section 12 and the read gate section 13, a vertical transfer electrode 16 to which a predetermined voltage signal is applied is formed. With such a configuration, in the solid-state imaging device, the signal charges accumulated in each photosensor unit 14 are sequentially transferred and output by the vertical transfer unit 12. Note that a light-shielding film 17 is provided above the vertical transfer electrode 16 to prevent light from being incident on the vertical transfer unit 12 and generating noise in signal charges during transfer. Further, above the photosensor section 14, the light shielding film 17 is cut, and a light receiving region 18 is formed so that the incident light enters the photosensor section 14, and the incident light is converted into signal charges to be converted into a signal charge. 14.
[0003]
Incidentally, the vertical transfer electrode 16 is constituted by a first transfer electrode 16a and a second transfer electrode 16b as shown in FIG. 4 as long as it corresponds to, for example, four-phase driving of the vertical transfer unit 12. A voltage signal corresponding to the four-phase driving is applied to each of the first transfer electrode 16a and the second transfer electrode 16b at a predetermined timing, whereby the potential of the vertical transfer unit 12 and the potential of the read gate unit 13 are reduced. To read out the signal charges from the photosensor unit 14 to the vertical transfer unit 12 and transfer the read-out signal charges in the vertical transfer unit 12.
[0004]
For such an operation, at least one of the first transfer electrode 16a and the second transfer electrode 16b also serves as an electrode for reading signal charges from the photo sensor unit 14 to the vertical transfer unit 12. Therefore, the first transfer electrode 16a or the second transfer electrode 16b, which also serves as a read electrode, is arranged so as to cover also above the read gate unit 13, as shown in FIG. Further, the first transfer electrode 16a and the second transfer electrode 16b are arranged so that a part thereof overlaps each other for four-phase driving of the vertical transfer unit 12, and for example, the first transfer electrode 16a and the second transfer electrode 16b As shown in FIG. 5B, the region has a two-layer structure in which the first transfer electrode 16a overlaps the second transfer electrode 16b with an interlayer insulating film interposed therebetween.
[0005]
Note that the conventional solid-state imaging device described here is based on a well-known and publicly-known technology, and is not related to the invention disclosed in the literature. Therefore, there is no prior art document information to be described here.
[0006]
[Problems to be solved by the invention]
By the way, in recent years, there has been an increasing demand for a solid-state imaging device to have a finer pixel size, that is, to reduce the size and density of the light receiving region 18. However, in the above-described conventional solid-state imaging device, the readout electrode for operating the readout gate unit 13 also functions as the transfer electrode for operating the vertical transfer unit 12, so that the pixel size can be reduced. It is conceivable that the above-described problem may occur.
[0007]
In the conventional solid-state imaging device, when a read voltage is applied to the entire read gate unit 13 in order to read the signal charges generated by the photo sensor unit 14 to the vertical transfer unit 12, the pixel separation unit 15 is inevitably applied to the read voltage. A read voltage will be applied. This must be avoided because signal charges are simultaneously read out from the photosensor units 14 adjacent in the vertical direction, which results in mixing of the signal charges. That is, when the read electrode also serves as the operating electrode of the vertical transfer unit 12, the read voltage can be applied only to a part of the read gate unit 13 instead of the entire read gate unit 13. Therefore, if the gate width of the readout gate unit 13 is reduced in accordance with the miniaturization of the pixel size, the readout voltage for sufficiently performing readout will increase. This can be a major obstacle to miniaturization of the pixel size.
[0008]
Further, in the conventional solid-state imaging device, since the readout electrode also serves as the operating electrode of the vertical transfer unit 12, when a readout voltage is applied, the potential of the buried channel, which is the vertical transfer unit 12, and the potential of the buried channel adjacent thereto are The potential difference between the potential of the channel stop portion 11 and the potential of the channel stop portion 11 may increase. Therefore, when the channel stop portion 11 is reduced in accordance with the miniaturization of the pixel size, a breakdown phenomenon due to a high electric field is likely to occur locally, and random noise is likely to occur. This can also be a major obstacle to miniaturization of the pixel size.
[0009]
Further, in the conventional solid-state imaging device, when the gate length of the readout gate unit 13 is reduced in accordance with the miniaturization of the pixel size, the distance between the vertical transfer unit 12 and the photosensor unit 14 is reduced. The smear characteristics may be degraded. This is the same for the channel stop unit 11. That is, even if the channel stop unit 11 is reduced, the distance between the vertical transfer unit 12 and the photo sensor unit 14 becomes short, which may cause deterioration of the anti-blooming characteristic and the smear characteristic. These factors also make it difficult to miniaturize the pixel size.
[0010]
Accordingly, it is an object of the present invention to provide a solid-state imaging device and a driving method thereof, which can solve the above-described problems and are very suitable for realizing miniaturization of a pixel size.
[0011]
[Means for Solving the Problems]
The present invention is a solid-state imaging device devised to achieve the above object, a photoelectric conversion unit that generates a signal charge according to the amount of incident light, and a charge transfer unit that transfers the signal charge received from the photoelectric conversion unit A transfer electrode to which a voltage for transferring a signal charge to the charge transfer unit is applied; a read gate unit for performing a signal charge read operation between the photoelectric conversion unit and the charge transfer unit; A read electrode to which a voltage for causing the gate portion to perform a read operation is provided, and the read electrode is formed independently of the transfer electrode.
[0012]
Further, the present invention is a driving method of a solid-state imaging device devised to achieve the above object. That is, a photoelectric conversion unit that generates a signal charge according to the amount of incident light, a charge transfer unit that transfers the signal charge received from the photoelectric conversion unit, and a voltage that causes the charge transfer unit to transfer the signal charge are applied. A transfer electrode, a read gate unit that performs a signal charge read operation between the photoelectric conversion unit and the charge transfer unit, and a read electrode to which a voltage for causing the read gate unit to perform a read operation is applied. And for a solid-state imaging device in which the readout electrode is formed independently of the transfer electrode, when reading signal charges from the photoelectric conversion unit to the charge transfer unit, only the readout electrode is used. Or applying a negative bias voltage to the readout electrode during the transfer of the signal charge in the charge transfer section.
[0013]
In the solid-state imaging device having the above configuration and the driving method of the solid-state imaging device having the above-described procedure, the readout electrode is formed independently of the transfer electrode. Therefore, for example, at the time of a signal charge readout operation, only the readout electrode is used. , A read operation can be performed by the read gate unit. That is, since a voltage can be applied only to the read electrode portion, the gate width of the read gate portion can be maximized and the read gate portion can be more widely used than before, and the read voltage can be easily reduced. In addition, since a voltage for a read operation is not applied to the transfer electrode, a potential difference that causes, for example, random noise hardly occurs. Further, for example, if a voltage that becomes a negative bias is applied to the read electrode during the transfer of the signal charge in the charge transfer unit, the potential of the region adjacent to the charge transfer unit can be made shallow, so that the anti-blooming property and the smear property can be reduced. Improvements can also be made.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a solid-state imaging device and a driving method thereof according to the present invention will be described with reference to the drawings.
[0015]
[First Embodiment]
First, a first embodiment of the present invention will be described. The embodiment described here is according to the first to fifth aspects of the present invention.
[0016]
FIG. 1 is a plan view schematically showing a first schematic configuration example of a main part of a solid-state imaging device according to the present invention, and FIG. 2 is a sectional view thereof. In the drawings and the following description, the same components as those of the related art (see FIGS. 3 to 5) are denoted by the same reference numerals.
[0017]
In the solid-state imaging device described here, a channel stop unit 11, a vertical transfer unit 12, a readout gate unit 13, a photosensor unit 14, a pixel separation unit 15, and a light-shielding film 17 However, as shown in FIG. 1, the vertical transfer electrode 1 and the readout electrode 2 are different from the conventional one, and the readout electrode 2 is formed independently of the vertical transfer electrode 1.
[0018]
The vertical transfer electrode 1 is applied with a voltage signal (hereinafter, referred to as “vertical transfer clock pulse”) for causing the vertical transfer unit 12 to transfer a signal charge, and includes a first transfer electrode 1 a and a second transfer electrode. 1b. However, as described above, since the vertical transfer electrode 1 is independent of the readout electrode 2, the vertical transfer electrode 1 is formed so as to be located only above the vertical transfer section 12, as shown in FIG. , Are not arranged so as to cover the upper part of the read gate unit 13.
[0019]
Further, as shown in FIG. 2B, the first transfer electrode 1a and the second transfer electrode 1b of the vertical transfer electrode 1 overlap each other on either the vertical transfer unit 12 or the pixel separation unit 15. And are insulated from each other by an insulating film for electrode separation.
[0020]
On the other hand, in FIG. 1, the read electrode 2 is for causing the read gate unit 13 to perform a read operation, and to which a read voltage signal required for the operation is applied. However, since the read electrode 2 is formed independently of the vertical transfer electrode 1, the read voltage signal can be applied completely independently.
[0021]
Further, as shown in FIG. 2A, the readout electrode 2 is disposed on the vertical transfer section 12 and the pixel separation section 15 so as to overlap the upper side of the vertical transfer electrode 1 with an interlayer insulating film interposed therebetween. . However, since the vertical transfer electrode 1 is located only above the vertical transfer unit 12, the upper part of the read gate unit 13 is covered by the read electrode 2.
[0022]
Further, since the readout electrode 2 is arranged so as to overlap the upper side of the vertical transfer electrode 1, the first transfer is performed on the vertical transfer unit 12 and the pixel separation unit 15 as shown in FIG. It also covers the boundary between the electrode 1a and the second transfer electrode 1b. Note that the readout electrode 2 only needs to cover at least a part of the boundary portion. That is, in a normal solid-state imaging device, a plurality of readout gates 13, a first transfer electrode 1a and a second transfer electrode 1b, a plurality of readout electrodes 2, and the like are provided corresponding to the photosensors 14 in a matrix. However, each boundary between the first transfer electrode 1a and the second transfer electrode 1b may be covered with any of the plurality of readout electrodes 2.
[0023]
The vertical transfer electrode 1 and the readout electrode 2 may be formed using a general electrode material represented by, for example, polysilicon. Also, the formation procedure may be performed using a well-known lithography technique, etching technique, or the like.
[0024]
Next, a driving method suitable for use in the solid-state imaging device configured as described above will be described. In driving the solid-state imaging device, first, a read voltage signal (for example, a 15 V pulse signal) is applied only to the read electrode 2. At this time, for the vertical transfer electrode 1, for example, the first transfer electrode 1a and the second transfer electrode 1b at positions corresponding to the photo sensor unit 14 to be read out are set to the high level (for example, 0V level) of the vertical transfer clock pulse. The other first transfer electrode 1a and second transfer electrode 1b are kept at a low level (for example, -8.5 V level).
[0025]
As a result, the vertical transfer unit 12 is in a state where its potential depth is capable of receiving signal charges from the photosensor unit 14, and the readout gate unit 13 uses the photosensor through the displacement of the potential depth in the readout gate unit 13. The operation of reading signal charges from the unit 14 to the vertical transfer unit 12 is performed. That is, at the time of the operation of reading the signal charges from the photo sensor unit 14 to the vertical transfer unit 12, a voltage is applied only to the read electrode 2.
[0026]
Then, after reading out the signal charge, the first transfer electrode 1a and the second transfer electrode 1b are subsequently subjected to, for example, the four-phase driving of the vertical transfer unit 12 if the case corresponds to the four-phase driving. Is applied at a predetermined timing. At this time, a voltage signal serving as a negative bias is applied to the read electrode 2.
[0027]
Thus, the vertical transfer unit 12 performs a transfer operation of the signal charges received from the photosensor unit 14 to a horizontal transfer unit (not shown) through the displacement of the potential depth in the vertical transfer unit 12. In other words, a voltage serving as a negative bias is applied to the readout electrode 2 during the transfer of the signal charges in the vertical transfer unit 12.
[0028]
By using the driving method as described above, in the solid-state imaging device described in the present embodiment, (1) lowering the read voltage, (2) suppressing random noise, (3) improving blooming resistance and smear characteristics. (4) It is possible to improve the transfer efficiency by canceling the potential dip. Hereinafter, these points will be sequentially described in detail in comparison with a solid-state imaging device having a conventional structure.
[0029]
First, (1) lowering the read voltage will be described. As described above, in the solid-state imaging device having the conventional structure, the readout electrode for operating the readout gate unit 13 also serves as the transfer electrode for operating the vertical transfer unit 12. When a read voltage is applied, signal charges are simultaneously read from the photosensor units 14 adjacent in the vertical direction. Therefore, in order to avoid mixing of signal charges, a read voltage can be applied only to a part of the read gate unit 13, not to the entire read gate unit 13. On the other hand, in the solid-state imaging device described in the present embodiment, when reading out the signal charges from the photosensor unit 14 to the vertical transfer unit 12, the readout voltage is not applied to the vertical transfer electrode 1 but is applied to the readout electrode 2. Only the voltage can be applied. That is, the read voltage can be applied only to the read gate unit 13 due to the presence of the dedicated read electrode 2. Therefore, the read voltage can be applied to the entire gate width of the read gate unit 13 without causing signal charges to be mixed. As a result, the gate width of the read gate unit 13 is made wider than that of the conventional structure, and the read voltage is increased. Can be reduced in voltage.
[0030]
Next, (2) suppression of random noise will be described. As described above, in the solid-state imaging device having the conventional structure, the readout electrode also serves as the operating electrode of the vertical transfer unit 12, so that when a readout voltage is applied, the potential of the lower part of the vertical transfer unit 12 becomes low. Therefore, the difference from the potential of the channel stop portion 11 adjacent thereto becomes large. Therefore, when the channel stop portion 11 is reduced in accordance with the miniaturization of the pixel size, a high electric field is generated between the vertical transfer portion 12 and the channel stop portion 11, and signal charges are generated due to a breakdown phenomenon. Noise is generated. On the other hand, in the solid-state imaging device described in the present embodiment, even when signal charges are read from the photosensor unit 14 to the vertical transfer unit 12, the first transfer electrode 1a and the second transfer electrode 1b Since the read voltage is not applied and only the signal of the high level state of the vertical transfer clock pulse is applied, the potential difference between the channel stop unit 11 and the vertical transfer unit 12 does not increase, and a high electric field hardly occurs. Therefore, generation of random noise due to the breakdown phenomenon can be suppressed.
[0031]
Next, (3) the improvement of blooming resistance and smear characteristics will be described. In the solid-state imaging device described in the present embodiment, since the readout electrode 2 is independent of the vertical transfer electrode 1, the negative bias is applied to the readout electrode 2 during the transfer of the signal charge in the vertical transfer unit 12. A voltage can be applied. That is, the potential of the read gate unit 13 and the potential of the channel stop unit 11 can be reduced by applying a negative bias. As a result, the potential barrier between the photosensor unit 14 and the vertical transfer unit 12 (particularly, the buried channel portion) increases, so that the gate length of the readout gate unit 13 decreases as the pixel size becomes smaller. Thus, even when the distance between the vertical transfer unit 12 and the photo sensor unit 14 is reduced, it is possible to prevent the smear characteristic from deteriorating as in the conventional structure. Further, the application of the negative bias makes it difficult for the potentials of the read gate unit 13 and the channel stop unit 11 to be modulated by the potential due to the vertical transfer clock pulse applied to the vertical transfer electrode 1. Can also be adjusted. Therefore, in the solid-state imaging device described in the present embodiment, the blooming resistance and smear characteristics during the vertical transfer period are improved by applying a negative bias voltage to the readout electrode 2 independent of the vertical transfer electrode 1. You can do it. The voltage of the negative bias applied at this time may be any voltage that is necessary and sufficient for improving the anti-blooming property and the smear property, that is, for controlling the potential barrier. What is necessary is just to determine based on the state of the potential specified from the formation material, size, etc. of the transfer part 12, the read gate part 13, etc.
[0032]
Finally, (4) the improvement of the transfer efficiency by canceling the potential dip will be described. In the solid-state imaging device described in the present embodiment, the first transfer electrode 1a and the second transfer electrode 1b are arranged in a single layer without overlapping each other. In the upper part of the vertical transfer part 12 and the pixel separation part 15, both are electrically separated by the electrode separation insulating film. In the case of such a single-layer structure, no voltage is applied to the portion of the insulating film for electrode separation. Therefore, normally, when the vertical transfer electrode 1 has a single layer, a potential dip (dent) is more likely to occur than in the case where the vertical transfer electrodes 16 partially overlap each other as in a solid-state imaging device having a conventional structure.
[0033]
The potential dip may be counteracted by, for example, implanting a P-type impurity into the lower portion of the electrode isolation insulating film by ion implantation. However, if the concentration of the P-type impurity added to cancel the potential dip is high, the P-type impurity tends to diffuse into the lower part of the vertical transfer electrode 1 by heat applied in the manufacturing process. When the P-type impurity is diffused as described above, a potential barrier is formed in the transfer direction, and as a result, transfer efficiency is deteriorated.
[0034]
On the other hand, in the solid-state imaging device described in the present embodiment, the readout electrode is formed so as to cover the portion of the insulating film for electrode separation, that is, the boundary between the first transfer electrode 1a and the second transfer electrode 1b. 2, the potential of the lower portion of the electrode isolation insulating film can be adjusted by applying a voltage to the readout electrode 2. That is, by applying a negative bias voltage to the read electrode 2 during the vertical transfer period, the potential at a portion below the boundary between the first transfer electrode 1a and the second transfer electrode 1b can be reduced. Therefore, the additional implantation amount of the P-type impurity for canceling the potential dip can be reduced or eliminated as compared with the case where no negative bias is applied, and the vertical transfer portion 12 caused by the potential barrier formed by the P-type impurity can be eliminated. , It is possible to prevent the transfer efficiency from deteriorating. The negative bias voltage at this time may be any voltage that is necessary and sufficient to prevent the transfer efficiency from deteriorating.
[0035]
This in other words makes it possible to realize a single layer of the vertical transfer electrode 1 without deteriorating the transfer efficiency in the vertical transfer unit 12. That is, in order to provide the readout electrode 2 independently of the vertical transfer electrode 1, even if the readout electrode 2 has a laminated structure arranged so as to overlap the upper side of the vertical transfer electrode 1 with the interlayer insulating film interposed therebetween, Since the vertical single-layer electrode 1 can be formed as a single layer, it is not necessary to change the height of the electrode portion in the height direction as compared with the conventional structure (when the vertical transfer electrode 16 has a two-layer structure). Therefore, even if the number of wirings arranged in the imaging region is increased by the amount corresponding to the readout electrode 2, it is possible to avoid an increase in the size of the imaging region.
[0036]
By realizing these (1) to (4), the solid-state imaging device and the driving method thereof described in the present embodiment can solve the problem associated with the miniaturization of the pixel size which occurs in the conventional structure. It can be said that it is very suitable for miniaturization of the pixel size, that is, miniaturization and high density of the light receiving region 18. Further, as the pixel size becomes finer, the degree of integration of the light receiving region 18 increases, so that it is expected that the number of pixels can be increased on the same optical size.
[0037]
It should be noted that the present embodiment is merely one specific example that realizes the present invention, and it is needless to say that the present invention is not limited to this. In particular, it goes without saying that the vertical single-layer electrode 1 and the vertical transfer section 12 may be of a type other than the four-phase drive. That is, the present invention is not limited to the specific examples described in the present embodiment, and can be appropriately changed without departing from the gist of the present invention.
[0038]
[Second embodiment]
Next, a second embodiment of the present invention will be described. The embodiment described here also relates to the first aspect of the present invention.
[0039]
FIG. 6 is a plan view schematically showing a second schematic configuration example of a main part of the solid-state imaging device according to the present invention, and FIGS. 7 to 10 are sectional views thereof. FIG. 11 is an explanatory diagram showing an example of a procedure for forming the solid-state imaging device. For comparison, a plan view of an example of a conventional solid-state imaging device having the same configuration is shown in FIG. 13 and sectional views thereof are shown in FIGS. 18 to 20 show an example of a procedure for forming a part of the solid-state imaging device. In these figures and in the following description, the same components as those already described (see FIGS. 1 to 5) are denoted by the same reference numerals.
[0040]
Here, first, the conventional solid-state imaging device shown in FIGS. The solid-state imaging device in the illustrated example is compatible with a so-called all-pixel readout method, and includes a channel stop unit 11, a vertical transfer unit 12, a readout gate unit 13, a photo sensor unit in an imaging region on a substrate (such as a silicon substrate). 14, a vertical transfer electrode 16c, 16d, 16e and a light shielding film 17. Among them, the read gate unit 13 is formed by using a thin P layer as shown in FIG. 16, thereby separating the vertical transfer unit 12 and the read gate unit 13 from each other. On the read gate section 13, there are vertical transfer electrodes 16c, 16d, and 16e formed by the procedure shown in FIGS. Therefore, in this solid-state imaging device, as shown in FIG. 17, by applying a voltage to the vertical transfer electrode 16e, the potential of the readout gate unit 13 together with the vertical transfer unit 12 is made lower than that of the photosensor unit 14, so that the photosensor The signal charges stored in the unit 14 can be read.
[0041]
However, in a solid-state imaging device that reads out such signal charges, the width and potential potential of the readout gate unit 13 may cause the influence of patterning deviation between the vertical transfer unit 12 and the photosensor unit 14 and the influence of impurity diffusion. Since it is directly received, it can be said that this is a very disadvantageous structure from the viewpoint of improving yield and promoting miniaturization. In addition, in such a conventional solid-state imaging device, a very large voltage is required when reading out signal charges. In addition, when a large amount of light is incident on the photo sensor unit 14, the vertical transfer unit 12 There is also a possibility that the charge leaks and causes blooming noise. In order to prevent this, it is conceivable to increase the concentration of the P layer of the read gate unit 13. However, in this case, the applied voltage required at the time of reading the charges is further increased.
[0042]
In order to solve these problems, for example, it is conceivable to arrange the readout gate unit 13 immediately below the portion where the light-shielding film 17 extends to the photosensor unit 14 and directly apply a voltage to the light-shielding film 17. However, in this case, there is a possibility that the light-shielding film 17 becomes a source of contamination to the substrate (such as a silicon substrate), induces lattice defects in silicon, and becomes a source of dark current. Therefore, it is not always preferable to apply a voltage directly to the light shielding film 17.
[0043]
On the other hand, the solid-state imaging device described in the present embodiment includes a channel stop unit 11, a vertical transfer unit 12, a readout gate unit 13, a photo sensor unit 14, In addition to the vertical transfer electrodes 16c, 16d, 16e and the light-shielding film 17, the read electrodes 2 are formed independently of the vertical transfer electrodes 16c, 16d, 16e and provided for applying a voltage to the read electrodes 2. A drive wiring 3 and a contact 3a between the readout electrode 2 and the drive wiring 3 are provided. Note that, in FIG. 6, the drawing of the vertical transfer electrode 16d from outside, the drawing of the vertical transfer electrode 16e from outside, and the illustration of the light shielding film 17 are omitted for simplicity.
[0044]
In the solid-state imaging device having such a configuration, as shown in FIG. 9, the vertical transfer electrode 16 e is located directly above the vertical transfer unit 12, and the readout electrode 2 is located directly above the readout gate unit 13. ing. The read electrode 2 partially overlaps with the vertical transfer electrode 16e. Above the read electrode 2 is a drive wiring 3 (or microcrystalline silicon or amorphous silicon) for driving the read electrode 2 from outside. Etc.) are routed. At this time, a thin oxide film or silicon nitride film may be interposed between the two.
[0045]
The driving wiring 3 is electrically connected to the readout electrode 2 via the contact 3a. That is, after forming the light-shielding film 17 above the readout electrode 2, a contact hole is formed in the light-shielding film 17, and the contact 3a is formed in that portion. However, as shown in FIG. 10, the drive wiring 3 may be formed at a position below the light shielding film 17 so as to be in direct contact with the readout electrode 2. In any case, the drive wiring 3 extends in the vertical direction of the two-dimensional matrix just above the vertical transfer electrodes 16c, 16d, and 16e, and is connected to an external power supply (not shown).
[0046]
The solid-state imaging device having such a configuration may be formed by a procedure as shown in FIG. First, as shown in FIG. 11A, a vertical transfer electrode 16e is formed on a substrate (such as a silicon substrate). As a forming method, after an electrode material is uniformly formed, patterning is performed using a photolithography technique or the like, excess electrode material is removed by dry etching or the like, and then the resist is peeled off to complete the process. As the electrode material at this time, it is conceivable to use a silicon-based material such as polysilicon, microcrystalline silicon, or amorphous silicon. Then, when the vertical transfer electrode 16e is formed, as shown in FIG. 11B, after forming an insulating layer, the readout electrode 2 is formed so as to partially overlap the vertical transfer electrode 16e. At this time, the length protruding from the vertical transfer electrode 16e is desirably about 0.01 to 1.0 μm. After the formation of the readout electrode 2, as shown in FIG. 11C, a light-shielding film 17 is formed after forming an insulating layer. Then, as shown in FIG. 11D, a hole for contact between the readout electrode 2 and the driving wiring 3 is formed, and as shown in FIG. 11E, the driving wiring 3 and the light shielding film 17 are short-circuited. An insulating layer for preventing the formation is formed. At this time, the insulating layer may be removed or left on the readout electrode 2 in either case. Finally, as shown in FIG. 11F, a drive wiring 3 for driving the readout electrode 2 and a contact 3a are formed.
[0047]
As described above, in the solid-state imaging device described in the present embodiment, the readout electrode 2 is formed independently of the vertical transfer electrodes 16c, 16d, and 16e. In exactly the same way, (1) lower read voltage, (2) suppress random noise, (3) improve blooming resistance and smear characteristics, and (4) improve transfer efficiency by canceling potential dips. It is possible to do. Therefore, it is possible to solve the problem associated with the miniaturization of the pixel size which occurs in the conventional structure, and it can be said that this is very suitable for realizing the miniaturization of the pixel size. Further, as the pixel size becomes finer, the degree of integration of the light receiving region also increases, so that it is expected that the number of pixels can be increased on the same optical size.
[0048]
Further, in the solid-state imaging device having the conventional structure, the readout gate unit 13 is formed by the P layer (see FIG. 16). However, in the solid-state imaging device described in the present embodiment, the readout electrode 2 is formed independently. Therefore, it is not necessary to form a P layer, and it is possible to form the read gate unit 13 without implanting any impurities. In such a case, at the time of charge transfer, the vertical transfer unit 12 and the photosensor unit 14 can be clearly separated by setting the voltage applied to the readout electrode 2 to the negative side. Also, at the time of charge reading, a very high voltage must be applied to lower the potential of the P layer if the P layer is used. Charges can be read.
[0049]
This is apparent from the potential shown in FIG. That is, comparing the potential in the example with the potential in the conventional structure (see FIG. 17), the signal charge is read out, but the vertical transfer electrode 16e is used in the conventional structure and the vertical transfer is used in the solid-state imaging device described in this embodiment. A voltage is applied to both the electrode 16e and the readout electrode 2, respectively. However, from the viewpoint of the potential movement from the initial state to the state where the charge readout is completed, it is apparent that the voltage is applied to both the vertical transfer electrode 16e and the readout electrode 2. It can be seen that the voltage is low.
[0050]
From these facts, the solid-state imaging device described in the present embodiment can suppress variations in the formation of the readout gate unit 13, and thus has a preferable structure from the viewpoint of improving yield and promoting miniaturization. In addition to this, the reading voltage of the signal charge can be suppressed as compared with the related art, and the occurrence of blooming noise and the like can be avoided. In addition, there is no danger of inducing a lattice defect of silicon to be a source of dark current.
[0051]
[Third Embodiment]
Next, a third embodiment of the present invention will be described. The embodiment described here is according to the invention described in claims 6 to 8, 11, and 12.
[0052]
FIG. 21 is a plan view schematically showing a third schematic configuration example of a main part of the solid-state imaging device according to the present invention, and FIGS. 22 and 23 are sectional views thereof. FIG. 24 is an explanatory diagram showing an example of a procedure for forming the solid-state imaging device. Further, FIGS. 25 and 26 are plan views schematically showing modified examples of the solid-state imaging device of FIG. In these figures and in the following description, the same components as those already described (especially, see FIGS. 6 to 20) are denoted by the same reference numerals.
[0053]
The solid-state imaging device described in the present embodiment has substantially the same configuration as that described in the second embodiment. However, as shown in FIGS. 2) and a second readout electrode 4, and drive wirings 3 and 5 and contacts 3 a and 5 for individually applying a voltage to each readout electrode 2 and 4. This is different from the above-described second embodiment. Then, due to the presence of the second readout electrode 4, not only the readout gate portion (hereinafter, referred to as “first readout gate portion”) 13 located directly below the first readout electrode 2 but also directly below the second readout electrode 4. The channel stop unit 11 can also function as a readout gate unit for reading out signal charges accumulated in the photosensor unit 14 to the vertical transfer unit 12. For this reason, in the present embodiment, the channel stop unit 11 is hereinafter referred to as a “second read gate unit”.
[0054]
That is, in the solid-state imaging device according to the present embodiment, if one of the photosensor units 14 adjacent to each other across the vertical transfer unit 12 is referred to as a “first photosensor unit” and the other is referred to as a “second photosensor unit”, A first readout gate unit 13 for reading out signal charges between the photosensor unit 14 and the vertical transfer unit 12, and a first voltage to which a voltage for causing the first readout gate unit 13 to perform a readout operation is applied. The readout electrode 2 and a second readout operation for reading signal charges between the second photosensor unit 14 and the vertical transfer unit 12, which is disposed at a position opposed to the first readout gate unit 2 with the vertical transfer unit 12 interposed therebetween. It includes a read gate unit 11 and a second read electrode 4 to which a voltage for causing the second read gate unit 11 to perform a read operation is applied. Each of the first readout electrode 2 and the second readout electrode 4 is formed independently of the vertical transfer electrodes 16c, 16d, and 16e.
[0055]
The solid-state imaging device having such a configuration may be formed by a procedure as shown in FIG. First, as shown in FIG. 24A, a vertical transfer electrode 16e is formed on a substrate (such as a silicon substrate) in the same manner as in the second embodiment. When the vertical transfer electrode 16e is formed, as shown in FIG. 24B, after forming an insulating layer, the first readout electrode 2 and the second readout electrode 4 are formed so as to partially overlap the vertical transfer electrode 16e. . At this time, the length protruding from the vertical transfer electrode 16e is desirably about 0.01 to 1.0 μm. The formation of each of the readout electrodes 2 and 4 may be performed by patterning using a photolithography technique or the like. Then, after the formation of the readout electrodes 2 and 4, as shown in FIG. 24C, an insulating layer is formed and a light-shielding film 17 is formed. Further, as shown in FIG. 24D, holes for contact between the readout electrodes 2 and 4 and the driving wirings 3 and 5 are separately formed, and then, as shown in FIG. An insulating layer for preventing short circuit between the wirings 3 and 5 and the light shielding film 17 is formed. At this time, the insulating layer may be removed or left on each of the readout electrodes 2 and 4. Finally, as shown in FIG. 24 (f), drive wirings 3, 5 and contacts 3a, 5a for individually driving the readout electrodes 2, 4 are formed.
[0056]
Here, a driving method suitable for use in the solid-state imaging device configured as described above will be described. In driving the solid-state imaging device, each of the first readout electrode 2 and the second readout electrode 4 is formed independently of the vertical transfer electrodes 16c, 16d, and 16e. Since the configuration is such that a voltage can be individually applied to each of the readout electrodes 2 and 4, the voltages applied to the first readout electrode 2 and the second readout electrode 4 are different so that the first readout is performed. Only one of the gate unit 13 and the second read gate unit 11 performs the read operation.
[0057]
More specifically, voltages having different potentials are applied to the read electrodes 2 and 4. For example, when only the first read gate unit 13 performs a read operation, a positive potential voltage is applied to the first read electrode 2 and a negative potential voltage is applied to the second read electrode 4. Thereby, in the solid-state imaging device, as shown in the potential diagram of FIG. 23, the first readout gate unit 13 corresponding to the first readout electrode 2 performs the readout operation, while the second readout corresponding to the second readout electrode 4 performs. The gate unit 11 functions as a channel stop unit that shields between the second photosensor unit 14 and the vertical transfer unit 12.
[0058]
Therefore, in the solid-state imaging device described in the present embodiment, the reading operation is performed in substantially the same manner as in the second embodiment. Therefore, as described in the second embodiment, in the conventional structure, It can be said that it is possible to solve the problem caused by the miniaturization of the pixel size, and it is very suitable for realizing the miniaturization of the pixel size by suppressing the manufacturing variation.
[0059]
In addition, the solid-state imaging device according to the present embodiment includes the first readout gate unit 13 and the second readout gate unit 11 on both sides of the vertical transfer unit 12, and these are individually separated by the first readout electrode 2 and the second readout electrode 4. In order to be able to operate, a driving method in which different potential voltages are applied to the respective readout electrodes 2 and 4 can be applied. Therefore, for example, by applying a negative potential voltage to the read electrode that does not perform the read operation, the potential difference between the read gate units 11 and 13 becomes apparent, and as a result, it is possible to avoid the occurrence of blooming noise and the like. It will be very effective.
[0060]
Further, in the solid-state imaging device of the present embodiment, the first readout gate unit 13 and the second readout gate unit 11 are provided on both sides of the vertical transfer unit 12, and these are individually separated by the first readout electrode 2 and the second readout electrode 4. Since it can be operated, signal charges can be selectively read from either the left or right side of the vertical transfer unit 12. That is, since the charges can be read independently from the right side or the left side of the vertical transfer unit 12, the degree of freedom of driving, flexibility, versatility, and the like are maintained high. be able to.
[0061]
In the solid-state imaging device according to the present embodiment, the first readout electrode 2 and the second readout electrode 4 may have a substantially L-shaped planar shape, for example, as shown in FIG. In addition, as shown in FIG. 26, for example, the planar arrangement of the driving wirings 3 and 5 is substantially adjusted in accordance with the planar shape of the first readout electrode 2 and the second readout electrode 4 being substantially L-shaped. Can be considered. By doing so, the area in which the contacts 3a and 5a can be formed is widened, so that high precision is not required at the time of formation, and as a result, the formation is facilitated.
[0062]
[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. The embodiment described here relates to the invention described in claims 6, 9, 10, 14, and 15.
[0063]
In each of the first to third embodiments described above, the example corresponding to the all-pixel readout method has been described as an example, but here, the example corresponding to the so-called pixel mixed readout method will be described. Note that the pixel mixed readout method does not read out signal charges from all the photosensor units 14 arranged in a two-dimensional matrix as in the all-pixel readout method, but selectively reads out signal charges in a thinning mode, for example. Is performed.
[0064]
FIG. 27 is a cross-sectional view schematically showing a fourth schematic configuration example of a main part of the solid-state imaging device according to the present invention, and FIG. 28 is an explanatory diagram showing an example of arrangement of color filters provided in the solid-state imaging device. In these figures and in the following description, the same components as those already described (especially, see FIGS. 21 to 26) are denoted by the same reference numerals.
[0065]
The solid-state imaging device described in the present embodiment has a configuration exactly the same as that described in the third embodiment, as shown in FIG. 27. This is different from the third embodiment described above. Accordingly, the arrangement of the color filters covering the light receiving area 18 of the photo sensor unit 14 is different from the conventional one.
[0066]
Here, the arrangement of the color filters will be briefly described. In a solid-state imaging device capable of supporting a color image, the light receiving areas 18 of the photosensor units 14 arranged in a two-dimensional matrix form color filters of R (red), G (green), and B (blue) color components. Although it is covered, its arrangement is generally as shown in FIG. That is, the arrangement of the conventional color filters is such that the R color component and the B color component are alternately filled between the G color components arranged in a checkered pattern. On the other hand, in the solid-state imaging device described in the present embodiment, as shown in FIG. 28A, when two light receiving regions 18 adjacent to each other are paired, the pair of light receiving regions 18 has the same color component. The color filter is configured to cover.
[0067]
Next, a driving method suitable for the above-described solid-state imaging device will be described.
[0068]
As described above, in the solid-state imaging device, the plurality of photosensor units 14 are arranged in a two-dimensional matrix. Then, the vertical transfer unit 12 that receives the signal charge from each photosensor unit 14 transfers the received signal charge in the vertical direction of the two-dimensional matrix. Conventionally, in a solid-state imaging device having such a structure, when a pixel mixture readout method is supported, for example, when an image is output in a thinning mode, the vertical direction in the photosensor unit 14 and the vertical transfer unit 12 is used. Although pixel addition is possible, horizontal pixel addition is not performed. For this reason, for example, when it is necessary to display or record with a reduced number of pixels at the time of capturing a moving image, conventionally, only one pixel of the two pixels in the vertical direction can be output, and another pixel of the signal charge can be output. Is not preferable from the viewpoint of the dynamic range of the signal output.
[0069]
On the other hand, in the solid-state imaging device described in the present embodiment, both the first readout electrode 2 and the second readout electrode 4 are formed independently of the vertical transfer electrodes 16c, 16d, and 16e, and the The configuration is such that a voltage can be individually applied to each of the readout electrodes 2 and 4 by the presence of the wirings 3 and 5. For this reason, in driving the solid-state imaging device, a positive potential voltage is simultaneously applied to the first readout electrode 2 and the second readout electrode 4. That is, both the first readout electrode 2 and the second readout electrode 4 perform the readout operation at the same time. As a result, the left and right photo sensor units 14 adjacent to each other with the vertical transfer unit 12 interposed therebetween can mix the signal charges accumulated therein and read out the mixed signal charges to the vertical transfer unit 12, resulting in horizontal pixel addition. Becomes possible.
[0070]
At this time, in the solid-state imaging device, the photosensor units 14 are arranged in a two-dimensional matrix, and the vertical transfer unit 12 that receives signal charges from each photosensor unit 14 transfers the received signal charges in the vertical direction of the two-dimensional matrix. Transfer to That is, the vertical transfer unit 12 functions as a so-called vertical transfer register in the two-dimensional matrix. Therefore, in order to simultaneously perform the read operation from the left and right photo sensor units 14 adjacent to each other with the vertical transfer unit 12 interposed therebetween, the plurality of vertical transfer units 12 arranged in parallel in the two-dimensional matrix are connected to one in the horizontal direction. What is necessary is just to make it operate every other.
[0071]
As described above, in the solid-state imaging device according to the present embodiment, when reading out the signal charges from the photosensor unit 14 to the vertical transfer unit 12, the first readout gate unit 13 and the second readout gate unit 11 that divide the signal charges are separated. By improving the controllability of the size of the pixel and adding a new first readout electrode 2 and a second readout electrode 4, low power consumption is achieved, and signal charges of horizontally adjacent pixels in a two-dimensional matrix are obtained. To perform the horizontal pixel addition.
[0072]
Therefore, according to the solid-state imaging device of the present embodiment, even when the pixel readout method is supported, the voltage can be simultaneously applied to both the first readout electrode 2 and the second readout electrode 4 so that Since the signal charges for two pixels can be mixed and output without sweeping out the signal charges for pixels, the dynamic range can be reduced by two compared to the case where pixel addition in the vertical direction is performed as in the conventional case. It becomes possible to double. Furthermore, if the vertical pixel addition is performed in the vertical transfer unit 12, the dynamic range can be quadrupled.
[0073]
In addition, since the amount of signal charge that can be output is at least twice as large as that in the case where pixel addition in the vertical direction is performed as in the related art, the gain adjustment of the output amplifier in the auto iris function when displaying the accumulated charge is performed. Can be performed more accurately than in the past.
[0074]
Moreover, in the solid-state imaging device according to the present embodiment, the color filters are arranged not in the conventional Bayer array system (see FIG. 28B), but are arranged so that the mixed photosensor units 14 have sensitivity to the same color. (See FIG. 28A), even when pixel addition is performed in the horizontal direction, it is possible to perform appropriate pixel addition without causing color mixing or the like and without deteriorating image quality. Become.
[0075]
[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. The embodiments described here also relate to the inventions described in claims 6 to 10 and 17 to 19.
[0076]
In each of the first to third embodiments described above, an example corresponding to the all-pixel readout method has been described as an example, and in each of the above-described fourth embodiments, an example corresponding to the pixel-mixed readout method has been described. Here, a description will be given by taking an example that can correspond to both types.
[0077]
The solid-state imaging device described in the present embodiment has substantially the same configuration as that described in the fourth embodiment, but the driving method is the same as that in the first to fourth embodiments. And different. More specifically, in the case of all-pixel reading, as described in the third embodiment, different potentials are applied to the first reading electrode 2 and the second reading electrode 4 to perform the first reading. The gate unit 13 and the second read gate unit 11 are individually operated to selectively read signal charges from either one of the left and right sides of the vertical transfer unit 12. On the other hand, in the case of pixel mixed read, as described in the fourth embodiment, a positive potential voltage is applied to the first read electrode 2 and the second read electrode 4 at the same time to 13 and the second read gate unit 11 simultaneously perform a read operation so that the signal charges accumulated in the left and right photo sensor units 14 adjacent to each other across the vertical transfer unit 12 are mixed and read.
[0078]
As a case corresponding to the all-pixel reading method, for example, a case corresponding to reading of a still image can be considered. Further, as a case of supporting the pixel mixture reading method, for example, a case of supporting reading of a moving image can be considered.
[0079]
Switching between the case of all-pixel reading and the case of pixel-mixing reading may be performed by a drive circuit of a solid-state imaging device (not shown). The switching operation in this drive circuit can be realized by using a known technique, and thus a detailed description thereof is omitted here.
[0080]
As described above, since the solid-state imaging device of the present embodiment can support both the all-pixel readout method and the pixel-mixed readout method, its versatility can be greatly enhanced. Moreover, in any case, as described in the third or fourth embodiment, it is possible to achieve a technical effect that cannot be obtained by the conventional solid-state imaging device.
[0081]
In addition, since the solid-state imaging device according to the present embodiment can support both the all-pixel readout method and the pixel-mixed readout method, the following operation can be performed. For example, in order to cope with the pixel mixture readout method, a positive potential voltage is simultaneously applied to the first readout electrode 2 and the second readout electrode 4 and simultaneously applied to both the first readout gate unit 13 and the second readout gate unit 11. After the readout operation is performed, voltages of different potentials are applied to the first readout electrode 2 and the second readout electrode 4 in order to support the all-pixel readout method, and the first readout gate unit 13 and the second readout gate unit In the case where only one of the readout operations is performed, the readout operation performed later (based on the all-pixels readout method) is performed based on the signal charges obtained by the previously performed readout operation (based on the pixel-mixed readout method). ) To adjust the gain of the amplifier. With this configuration, the gain adjustment of the amplifier in the auto iris function that outputs and displays the accumulated charge transferred by the all-pixel reading method as a current is determined by the accumulated charge transferred by the immediately preceding pixel mixed reading method. Therefore, simplification and higher precision can be expected.
[0082]
[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described. The embodiment described here also relates to the first aspect of the present invention.
[0083]
FIG. 29 is a plan view schematically showing a fifth schematic configuration example of the main part of the solid-state imaging device according to the present invention, and FIG. 30 is a sectional view thereof. FIG. 31 is an explanatory diagram showing a modification of the solid-state imaging device shown in FIG. In these figures and in the following description, the same components as those already described (especially, see FIGS. 1 to 5) are denoted by the same reference numerals.
[0084]
The solid-state imaging device described here is compatible with a so-called interlace (interlaced scanning) system. The interlace method is widely known as a television scanning method of a document, and is a method in which scanning lines extending in the horizontal direction are scanned not every other operation but every other line.
[0085]
Conventionally, as described above, as a solid-state imaging device compatible with the interlace system, there is known a solid-state imaging device that includes a first transfer electrode 16a and a second transfer electrode 16b and performs four-phase driving of the vertical transfer unit 12. (See FIG. 4).
On the other hand, the solid-state imaging device described in the present embodiment includes, as shown in FIGS. 29 and 30, the readout electrode 2 formed independently of the vertical transfer electrodes 16a and 16b. The solid-state imaging device shown in the drawing is common to the above-described all-pixel readout method (the first or second embodiment) in that the readout electrode 2 is provided independently, but the readout electrode 2 is used. 2 in that it is routed to the outside of the solid-state imaging device as it is. The number of externally input terminals for driving is increased by two. Needless to say, even in the case of the all-pixel readout method, the readout electrode 2 may be extended to the outside.
[0086]
When an image is read by the interlace method using the solid-state imaging device having such a configuration, it is possible to cope with either of so-called field reading and so-called frame reading. In the field reading, the signal charges of two adjacent pixels are mixed by the vertical transfer unit 12 to obtain a signal of each field. To that end, a voltage may be applied to each readout electrode 2 so that the combination of pixels mixed in each field changes. Note that the pixel mixture at this time is the same as in the related art, and a description thereof will be omitted. On the other hand, in frame reading, interlaced scanning is supported by switching and reading out odd-numbered and even-numbered pixels in each field. Therefore, in the case of frame reading, a voltage may be alternately applied to the read electrodes 2 extending in the horizontal direction every other one in the vertical direction.
[0087]
With the above driving method, the solid-state imaging device described in the present embodiment can support both frame reading and field reading. Moreover, in the solid-state imaging device according to the present embodiment, the readout electrode 2 is formed independently of the vertical transfer electrodes 16a and 16b. Just as in the case of the first embodiment, it is possible to realize a reduction in the read voltage, a suppression of the fabrication variation, and the avoidance of noise.
[0088]
By the way, when the readout electrode 2 is routed as it is to the outside of the solid-state imaging device, the readout electrode 2 does not necessarily need to extend in the horizontal direction. For example, if only the field readout is supported, the readout electrode 2 may be routed to the outside of the solid-state imaging device as it is so that the readout electrode 2 extends in the vertical direction as shown in FIG. Even in this case, by making the readout electrode 2 independent of the vertical transfer electrodes 16a and 16b, it is possible to realize a low readout voltage, avoidance of noise, and the like.
[0089]
[Seventh Embodiment]
Next, a seventh embodiment of the present invention will be described. The embodiment described here relates to the inventions according to claims 6 to 19, and particularly relates to the inventions according to claims 13 and 16.
[0090]
FIG. 32 is a plan view schematically showing a sixth schematic configuration example of the main part of the solid-state imaging device according to the present invention, and FIG. 33 is a sectional view thereof. FIG. 34 is an explanatory diagram showing a modification of the solid-state imaging device shown in FIG. In these drawings and in the following description, the same components as those already described are denoted by the same reference numerals.
[0091]
The solid-state imaging device described here is also compatible with the interlaced system as in the case of the sixth embodiment. However, as shown in FIGS. The third embodiment is different from the sixth embodiment in that a read electrode 4 is provided and each of the read electrodes 2 and 4 is separately routed to the outside of the solid-state imaging device. That is, the solid-state imaging device described here has substantially the same configuration as that of the third to fifth embodiments.
[0092]
When an image is read by an interlace method using the solid-state imaging device having such a configuration, it is possible to perform field reading, frame reading, and horizontal pixel addition. In particular, when performing field readout, it is possible to perform pixel addition in the horizontal direction instead of or in combination with pixel mixing in the vertical direction. The horizontal pixel addition at this time may be performed as described in the fourth or fifth embodiment. At this time, the vertical transfer unit 12 may be operated every other one in the horizontal direction. That is, a voltage may be applied to the vertical transfer electrodes 16a and 16b every other row in the horizontal direction.
[0093]
With the above driving method, the solid-state imaging device described in the present embodiment can support both frame reading and field reading. In addition, in the solid-state imaging device according to the present embodiment, since both the first readout electrode 2 and the second readout electrode 4 are formed independently of the vertical transfer electrodes 16a and 16b, the solid-state imaging device corresponds to the interlace method. As in the case of the first or second embodiment described above, it is possible to realize a reduction in the read voltage, suppression of the variation in fabrication, avoidance of noise, and the like. Furthermore, since pixel addition in the horizontal direction can be performed in the same manner as in the third to fifth embodiments described above, the degree of freedom of driving, flexibility, versatility, etc. can be maintained at a high level. On the other hand, it is very advantageous in terms of dynamic range and gain adjustment of the output amplifier.
[0094]
Incidentally, when the first readout electrode 2 and the second readout electrode 4 are routed as they are to the outside of the solid-state imaging device, they need not necessarily extend in the horizontal direction, and correspond to, for example, field readout and horizontal pixel addition. In this case, as shown in FIG. 34, the first readout electrode 2 and the second readout electrode 4 may extend in the vertical direction. Also in this case, by making the first readout electrode 2 and the second readout electrode 4 independent of the vertical transfer electrodes 16a and 16b, it is possible to realize a reduction in the readout voltage and a degree of freedom in driving. In addition, in the case of the configuration of FIG. 32, the number of terminals input from the outside for driving increases by four, but in the case of the configuration of FIG. 34, the number of terminals only needs to increase by two.
[0095]
It should be noted that the above-described second to seventh embodiments are also merely specific examples of realizing the present invention, and it is needless to say that the present invention is not limited to this. For example, when the first read gate unit 13 and the second read gate unit 11 and the first read electrode 2 and the second read electrode 4 are formed on the left and right of the vertical transfer unit 12, all the vertical transfer units 12 in the two-dimensional matrix are used. However, it is not necessary to provide these on the left and right, and it is also conceivable to arrange them appropriately as appropriate. That is, the present invention is not limited to the specific examples described in the present embodiment, and can be appropriately changed without departing from the gist thereof.
[0096]
【The invention's effect】
As described above, according to the solid-state imaging device and the driving method thereof according to the present invention, the readout electrodes are formed independently of the transfer electrodes. Therefore, for example, by applying a voltage to only the readout electrode during the signal charge readout operation, or by applying a negative bias voltage to the readout electrode during the transfer of the signal charge in the charge transfer unit. Since it is possible to lower the read voltage, suppress random noise, improve the anti-blooming characteristics and the smear characteristics, etc., it is very easy to cope with the miniaturization of the pixel size as compared with the related art. Further, since the degree of integration of the pixel portion increases with the miniaturization of the pixel size, the realization of multi-pixels on the same optical size can be expected.
[Brief description of the drawings]
FIG. 1 is a plan view schematically showing an example of a schematic configuration of a main part of a solid-state imaging device according to the present invention.
FIGS. 2A and 2B are cross-sectional views schematically showing an example of a schematic configuration of a main part of the solid-state imaging device according to the present invention, wherein FIG. 2A is a cross-sectional view taken along line AA ′ in FIG. FIG. 2 is a view showing a BB ′ cross section of FIG.
FIG. 3 is a schematic diagram illustrating a configuration example of an imaging area of a solid-state imaging device.
FIG. 4 is a plan view schematically showing a schematic configuration example of a main part of a conventional solid-state imaging device.
5A and 5B are cross-sectional views schematically illustrating an example of a schematic configuration of a main part of a conventional solid-state imaging device, where FIG. 5A is a cross-sectional view taken along the line CC ′ in FIG. 4, and FIG. FIG. 4 is a diagram showing a cross section taken along the line DD ′.
FIG. 6 is a plan view schematically showing a second schematic configuration example of the main part of the solid-state imaging device according to the present invention.
7 is a cross-sectional view (part 1) schematically illustrating a second schematic configuration example of a main part of the solid-state imaging device according to the present invention, and is a diagram illustrating a cross section taken along line EE ′ in FIG.
FIG. 8 is a cross-sectional view (part 2) schematically illustrating a second schematic configuration example of a main part of the solid-state imaging device according to the present invention, and is a view illustrating a cross section taken along line FF ′ in FIG.
9 is a cross-sectional view (part 3) schematically showing a second schematic configuration example of a main part of the solid-state imaging device according to the present invention, and is a view showing a GG ′ cross-section in FIG. 6;
FIG. 10 is a sectional view (part 4) schematically showing a second schematic configuration example of a main part of the solid-state imaging device according to the present invention, and shows another example of a GG ′ cross section in FIG. 6; FIG.
FIG. 11 is an explanatory diagram showing an example of a forming procedure of a second schematic configuration example of a main part of the solid-state imaging device according to the present invention.
FIG. 12 is a cross-sectional view (part 5) schematically illustrating a second schematic configuration example of a main part of the solid-state imaging device according to the present invention, and is a diagram illustrating an example of a potential state.
FIG. 13 is a plan view schematically illustrating a schematic configuration example of a main part of a conventional solid-state imaging device.
14 is a cross-sectional view (part 1) schematically showing an example of a schematic configuration of a main part of a conventional solid-state imaging device, and is a view showing a cross section taken along line HH ′ in FIG.
FIG. 15 is a cross-sectional view (part 2) schematically showing an example of a schematic configuration of a main part of a conventional solid-state imaging device, and is a diagram showing a II-I cross section in FIG.
16 is a cross-sectional view (part 3) schematically showing a schematic configuration example of a main part of a conventional solid-state imaging device, and is a view showing a JJ ′ cross-section in FIG.
FIG. 17 is a cross-sectional view (part 4) schematically showing an example of a schematic configuration of a main part of a conventional solid-state imaging device, showing an example of a potential state.
FIG. 18 is an explanatory diagram (part 1) illustrating an example of a procedure for forming a part of a conventional solid-state imaging device.
FIG. 19 is an explanatory diagram (part 2) illustrating an example of a procedure for forming a part of a conventional solid-state imaging device.
FIG. 20 is an explanatory view (part 3) of an example of a procedure for forming a part of a conventional solid-state imaging device;
FIG. 21 is a plan view schematically showing a third schematic configuration example of the main part of the solid-state imaging device according to the present invention.
22 is a cross-sectional view (No. 1) schematically illustrating a third schematic configuration example of a main part of the solid-state imaging device according to the present invention, and is a diagram illustrating a cross section taken along line KK ′ in FIG. 21.
23 is a cross-sectional view (part 2) schematically illustrating a third schematic configuration example of a main part of the solid-state imaging device according to the present invention, and is a view illustrating a cross section taken along line LL ′ in FIG. 21.
FIG. 24 is an explanatory diagram showing an example of a forming procedure of a third schematic configuration example of a main part of the solid-state imaging device according to the present invention.
FIG. 25 is a plan view (part 1) schematically showing a modification of the third schematic configuration of the main part of the solid-state imaging device according to the present invention.
FIG. 26 is a plan view (part 2) schematically showing a modification of the third schematic configuration of the main part of the solid-state imaging device according to the present invention.
27 is a cross-sectional view schematically illustrating a fourth schematic configuration example of a main part of the solid-state imaging device according to the present invention, and is a view illustrating a cross section taken along line LL ′ in FIG. 21.
FIGS. 28A and 28B are explanatory diagrams illustrating an example of the arrangement of color filters included in the solid-state imaging device according to the present invention. FIG. 28A is a diagram illustrating a specific example thereof, and FIG. FIG.
FIG. 29 is a plan view schematically showing a fifth schematic configuration example of the main part of the solid-state imaging device according to the present invention.
30 is a cross-sectional view schematically illustrating a fifth schematic configuration example of a main part of the solid-state imaging device according to the present invention, and is a diagram illustrating a cross section taken along line MM ′ in FIG. 29.
FIG. 31 is an explanatory view schematically showing a modified example of the fifth schematic configuration of the main part of the solid-state imaging device according to the present invention.
FIG. 32 is a plan view schematically showing a sixth schematic configuration example of the main part of the solid-state imaging device according to the present invention.
FIG. 33 is a cross-sectional view schematically showing a sixth schematic configuration example of a main part of the solid-state imaging device according to the present invention, and is a view showing an NN ′ cross-section in FIG. 32.
FIG. 34 is an explanatory diagram schematically showing a modified example of the sixth schematic configuration of the main part of the solid-state imaging device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Vertical transfer electrode, 1a ... 1st transfer electrode, 1b ... 2nd transfer electrode, 2 ... Readout electrode (1st readout electrode), 4 ... 2nd readout electrode, 11 ... Channel stop part (2nd readout gate) 12) vertical transfer unit, 13 readout gate unit (first readout gate unit), 14 photosensor unit, 15 pixel separation unit

Claims (19)

A photoelectric conversion unit that generates a signal charge according to the amount of incident light;
A charge transfer unit that transfers the signal charge received from the photoelectric conversion unit,
A transfer electrode to which a voltage for transferring a signal charge to the charge transfer unit is applied;
A read gate unit that performs a signal charge read operation between the photoelectric conversion unit and the charge transfer unit;
A read electrode to which a voltage for causing the read gate unit to perform a read operation is provided;
The solid-state imaging device, wherein the readout electrode is formed independently of the transfer electrode. The solid-state imaging device according to claim 1, wherein the transfer electrode includes a plurality of electrode portions arranged in a single layer without overlapping each other. 3. The solid-state imaging device according to claim 2, wherein the readout electrode is disposed so as to cover at least a part of a boundary portion between the electrode portions. A photoelectric conversion unit that generates a signal charge according to the amount of incident light;
A charge transfer unit that transfers the signal charge received from the photoelectric conversion unit,
A transfer electrode to which a voltage for transferring a signal charge to the charge transfer unit is applied;
A read gate unit that performs a signal charge read operation between the photoelectric conversion unit and the charge transfer unit;
A read electrode to which a voltage for causing the read gate unit to perform a read operation is provided;
For a solid-state imaging device in which the readout electrode is formed independently of the transfer electrode,
A driving method for a solid-state imaging device, wherein a voltage is applied only to the readout electrode during an operation of reading out signal charges from the photoelectric conversion unit to the charge transfer unit. A photoelectric conversion unit that generates a signal charge according to the amount of incident light;
A charge transfer unit that transfers the signal charge received from the photoelectric conversion unit,
A transfer electrode to which a voltage for transferring a signal charge to the charge transfer unit is applied;
A read gate unit that performs a signal charge read operation between the photoelectric conversion unit and the charge transfer unit;
A read electrode to which a voltage for causing the read gate unit to perform a read operation is provided;
For a solid-state imaging device in which the readout electrode is formed independently of the transfer electrode,
A method for driving a solid-state imaging device, characterized in that a voltage serving as a negative bias is applied to the readout electrode during the transfer of signal charges in the charge transfer section. A first photoelectric conversion unit that generates a signal charge according to the amount of incident light,
A second photoelectric conversion unit juxtaposed with the first photoelectric conversion unit,
A charge transfer unit disposed between the first photoelectric conversion unit and the second photoelectric conversion unit, and transferring a signal charge received from each photoelectric conversion unit,
A transfer electrode to which a voltage for transferring a signal charge to the charge transfer unit is applied, and a first read gate unit that performs a signal charge read operation between the first photoelectric conversion unit and the charge transfer unit,
A first read electrode to which a voltage for causing the first read gate unit to perform a read operation is applied;
A second read gate unit disposed at a position facing the first read gate unit and the charge transfer unit, and performing a signal charge read operation between the second photoelectric conversion unit and the charge transfer unit;
A second read electrode to which a voltage for causing the second read gate unit to perform a read operation is applied,
The solid-state imaging device, wherein both the first readout electrode and the second readout electrode are formed independently of the transfer electrode. Either the first readout gate unit or the second readout gate unit functions as a channel stop unit that shields between the first photoelectric conversion unit or the second photoelectric conversion unit and the charge transfer unit. The solid-state imaging device according to claim 6, wherein: The solid-state imaging device according to claim 6, wherein a voltage is individually applied to each of the first readout electrode and the second readout electrode. The solid-state imaging device according to claim 6, wherein the first photoelectric conversion unit and the second photoelectric conversion unit adjacent to each other across the charge transfer unit are provided with a color filter of the same color component. 7. The device according to claim 6, wherein the first photoelectric conversion unit and the second photoelectric conversion unit are arranged in a two-dimensional matrix, and the charge transfer unit functions as a vertical transfer unit in the two-dimensional matrix. Solid-state imaging device. A first photoelectric conversion unit that generates a signal charge according to the amount of incident light,
A second photoelectric conversion unit juxtaposed with the first photoelectric conversion unit,
A charge transfer unit disposed between the first photoelectric conversion unit and the second photoelectric conversion unit, and transferring a signal charge received from each photoelectric conversion unit,
A transfer electrode to which a voltage for transferring a signal charge to the charge transfer unit is applied, and a first read gate unit that performs a signal charge read operation between the first photoelectric conversion unit and the charge transfer unit,
A first read electrode to which a voltage for causing the first read gate unit to perform a read operation is applied;
A second read gate unit disposed at a position facing the first read gate unit and the charge transfer unit, and performing a signal charge read operation between the second photoelectric conversion unit and the charge transfer unit;
A second read electrode to which a voltage for causing the second read gate unit to perform a read operation is applied,
For the solid-state imaging device wherein both the first readout electrode and the second readout electrode are formed independently of the transfer electrode,
A voltage to be applied to the first read electrode and the second read electrode is made different, and only one of the first read gate unit and the second read gate unit performs a read operation. A method for driving a solid-state imaging device. In causing only one of the first read gate unit and the second read gate unit to perform a read operation, voltages of different potentials are applied to the first read electrode and the second read electrode. The method of driving a solid-state imaging device according to claim 11, wherein: The driving method of a solid-state imaging device according to claim 11, wherein the driving method corresponds to reading of signal charges by a frame reading method. A first photoelectric conversion unit that generates a signal charge according to the amount of incident light,
A second photoelectric conversion unit juxtaposed with the first photoelectric conversion unit,
A charge transfer unit disposed between the first photoelectric conversion unit and the second photoelectric conversion unit, and transferring a signal charge received from each photoelectric conversion unit,
A transfer electrode to which a voltage for transferring a signal charge to the charge transfer unit is applied;
A first read gate unit that performs a read operation of signal charges between the first photoelectric conversion unit and the charge transfer unit,
A first read electrode to which a voltage for causing the first read gate unit to perform a read operation is applied;
A second read gate unit disposed at a position facing the first read gate unit and the charge transfer unit, and performing a signal charge read operation between the second photoelectric conversion unit and the charge transfer unit;
A second read electrode to which a voltage for causing the second read gate unit to perform a read operation is applied,
For the solid-state imaging device wherein both the first readout electrode and the second readout electrode are formed independently of the transfer electrode,
A voltage of the same potential is simultaneously applied to the first readout electrode and the second readout electrode, so that both the first readout gate unit and the second readout gate unit perform a readout operation at the same time. A method for driving a solid-state imaging device. When the first photoelectric conversion unit and the second photoelectric conversion unit are arranged in a two-dimensional matrix, and the plurality of charge transfer units are arranged in parallel in the two-dimensional matrix, the first readout gate unit And causing the plurality of charge transfer units arranged in parallel to operate every other in the horizontal direction in the two-dimensional matrix when simultaneously performing the read operation on both the first and second read gate units. Item 15. A method for driving a solid-state imaging device according to Item 14. 15. The driving method of a solid-state imaging device according to claim 14, wherein the method corresponds to reading of signal charges by a field reading method. A first photoelectric conversion unit that generates a signal charge according to the amount of incident light,
A second photoelectric conversion unit juxtaposed with the first photoelectric conversion unit,
A charge transfer unit disposed between the first photoelectric conversion unit and the second photoelectric conversion unit, and transferring a signal charge received from each photoelectric conversion unit,
A transfer electrode to which a voltage for transferring a signal charge to the charge transfer unit is applied, and a first read gate unit that performs a signal charge read operation between the first photoelectric conversion unit and the charge transfer unit,
A first read electrode to which a voltage for causing the first read gate unit to perform a read operation is applied;
A second read gate unit disposed at a position facing the first read gate unit and the charge transfer unit, and performing a signal charge read operation between the second photoelectric conversion unit and the charge transfer unit;
A second read electrode to which a voltage for causing the second read gate unit to perform a read operation is applied,
For the solid-state imaging device wherein both the first readout electrode and the second readout electrode are formed independently of the transfer electrode,
In the case of all-pixel reading, only one of the first read gate unit and the second read gate unit performs a read operation,
A method for driving a solid-state imaging device, wherein in the case of pixel mixture readout, both the first readout gate unit and the second readout gate unit perform a readout operation simultaneously. 18. The driving method for a solid-state imaging device according to claim 17, wherein the all-pixel reading is performed when a still image is supported, and the pixel mixed reading is performed when a moving image is supported. After causing both the first read gate unit and the second read gate unit to perform the read operation at the same time, when performing the read operation on only one of the read operation, the read operation obtained earlier is obtained. 18. The method for driving a solid-state imaging device according to claim 17, wherein gain adjustment of an amplifier at the time of a read operation performed later is performed based on the signal charge.

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