JP2002170947A - Solid state image sensing device and imaging system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid state image sensing device which is immune to the alignment or ion implanting angle and capable of reading signals at a high speed. SOLUTION: The solid state image sensing device comprises a plurality of vertical charge transfer lines 2 arranged at pitches A in a horizontal direction in photoelectric conversion regions, and at pitches B narrower than the pitch A in regions for inputting signals to horizontal charge transfer lines 17, 18,..., 19 for receiving signals from the vertical charge transfer lines. The horizontal charge transfer lines 17, 18,..., 19 and the read amplifiers 31a, 31b,..., 31c are disposed every block, in photoelectric conversion blocks 11, 12,..., 13 into which the photoelectric conversion regions are divided. Each read amplifier is disposed at a region ensured by the pitch change of the vertical charge transfer line so as to hold a mutually translated positional relation in the same shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a solid-state imaging device and an imaging system using the same. The present invention particularly provides an element structure suitable for a solid-state imaging device capable of high-speed reading.

[0002]

2. Description of the Related Art As one means for reading out image data at a high speed in an image pickup device, there is a method of dividing a photoelectric conversion region into a plurality of sections and reading out electric charges from each section in parallel.
For example, Japanese Patent Laying-Open No. 3-224371 proposes a structure (FIG. 10) in which read amplifiers are arranged mirror-symmetrical (linearly symmetric) with each other. In this solid-state imaging device,
A signal is output from each pixel arranged in a matrix in the pixel units 31 and 32 via a horizontal charge transfer path 33 and readout amplifiers 34 and 35 arranged at both ends of the horizontal charge transfer path in this order. .

[0003]

However, when the read amplifiers 34 and 35 are arranged in mirror symmetry with each other,
At the transistor level, the source (S) and the drain (D) must be arranged mirror-symmetrically about the gate (G) (FIG. 11B). For this reason,
The misalignment caused in the mask alignment step of semiconductor manufacturing, coupled with the influence of the implantation angle dependence in the impurity ion implantation step, makes it difficult to manufacture a read amplifier having uniform input / output characteristics.

[0004] The difference in the characteristics of the read amplifier causes a problem that when an image is reproduced, the image is observed as being blocked. Further, when the read data is combined and displayed as one image, it is necessary to rearrange the image data using a memory or the like, which complicates the signal processing. In the arrangement shown in FIG. 11A, a mask shift or the like in the lithographic process equally affects different amplifiers, and thus does not cause a characteristic difference between the amplifiers. However, in the arrangement of FIG. 11B, deviations in ion implantation and mask alignment in the manufacturing process cause different effects between different amplifiers, and cause a difference in characteristics between the amplifiers.

In order to solve the above-mentioned conventional problems, the present invention has a structure which is hardly affected by misalignment of a mask for manufacturing a semiconductor and an ion implantation angle, and reads out signals by a plurality of amplifiers to form one image. It is another object of the present invention to provide a structure of a solid-state imaging device in which signal processing is easy even when displaying.

[0006]

In order to achieve the above object, a solid-state imaging device according to the present invention comprises a plurality of photoelectric conversion units arranged in a matrix along a vertical direction and a horizontal direction, and a row of the photoelectric conversion units. A photoelectric conversion region including a plurality of vertical charge transfer paths extending along a horizontal charge transfer path for receiving signals from the plurality of vertical charge transfer paths, wherein the plurality of vertical charge transfer paths Are arranged in the photoelectric conversion region at a pitch A in the horizontal direction, and the pitch A is input at a portion where a signal is input to the horizontal charge transfer path.
It is characterized by being arranged at a pitch B smaller than that.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the solid-state imaging device of the present invention, the pitch B of the vertical charge transfer path in a portion where a signal is input to the horizontal charge transfer path is smaller than the pitch A of the vertical charge transfer path in the photoelectric conversion region. (A> B). Therefore, when the number of lines of the vertical charge transfer path is N, (N
-1) A space S having a width shown by (AB) is generated. This space S can be used as a region where a read amplifier is arranged. Also, in the case where the photoelectric conversion region is divided into a plurality of sections and the readout amplifiers are arranged in each section, by using the space S, the plurality of readout amplifiers can be moved from one side to the other side by parallel movement. Can be arranged so that FIG. 11A illustrates an example of a positional relationship that can be moved by parallel movement.

With this arrangement, it is possible to suppress the influence of misalignment and the implantation angle of impurities in the manufacturing process. Further, since the peripheral circuit and the wiring leading to this circuit can be formed in the same pattern, it is easy to eliminate the characteristic difference between these circuits and the wiring. Further, with regard to signal processing, each section (photoelectric conversion block) of the photoelectric conversion region corresponding to one read amplifier can be arranged so as to have the same shape and the same horizontal read direction of the corresponding pixel. Therefore, it is possible to obtain a solid-state imaging device in which the complexity of data rearrangement required when the pixels are arranged in mirror symmetry is eliminated.

In a preferred embodiment of the present invention, the solid-state image pickup device is configured such that a signal is transmitted from a vertical charge transfer path in each of the sections obtained by dividing the photoelectric conversion region along the vertical direction (in other words, for each photoelectric conversion block). And a readout amplifier for receiving the horizontal charge transfer path. In this case, by utilizing the space S, a horizontal charge transfer path and a readout amplifier that receive signals from a vertical charge transfer path in the area at intervals equal to or less than the width of the area into which the photoelectric conversion region is divided in the horizontal direction. Is preferably arranged. This preferred embodiment realizes a structure in which the number of photoelectric conversion blocks arranged in the horizontal direction is not limited. More specifically, a plurality of solid-state imaging devices having substantially the same shape are defined as an area (photoelectric conversion block) obtained by dividing a photoelectric conversion region, a horizontal charge transfer path for receiving a signal from this area, and a readout amplifier as one solid-state imaging block. The blocks may be arranged along the horizontal direction. This is because a uniform image can be easily obtained.

Further, even at the boundaries of the photoelectric conversion blocks, arranging the vertical charge transfer paths at a pitch A in the horizontal direction is advantageous in eliminating image distortion and the like.

The width of the vertical charge transfer path in the horizontal direction is preferably substantially constant from the end of the photoelectric conversion area to the end of the horizontal charge transfer path. It may be increased gradually or stepwise toward the end of the transfer path.

In a typical form of the vertical charge transfer path,
When observed in a plan view, a bent portion (bent portion) is observed. In this case, transfer deterioration may occur at the bent portion, but this transfer deterioration can be suppressed by several methods.

For example, a plurality of transfer electrodes wired at least to the bent portion of the vertical charge transfer path so that a transfer drive pulse can be applied independently of other portions of the vertical charge transfer path are provided on the vertical charge transfer path. It is good to arrange in. If this arrangement is adopted, it becomes possible to apply an appropriate transfer pulse to the bent portion independently.

Usually, it is preferable to arrange a plurality of transfer electrodes so that the bent portion of the vertical charge transfer path is located between the transfer electrodes rather than under the transfer electrodes. However, even when the bent portion is located below the predetermined transfer electrode, the transfer path length to which the transfer drive pulse is applied by the predetermined transfer electrode is determined by the transfer electrode adjacent to the predetermined transfer electrode. It is preferable that the length be shorter than the transfer path length to which the transfer drive pulse is applied.

The bending angle of the bent portion is 45 at the maximum.
It is preferable that the temperature be equal to or less than the temperature. When the group of vertical charge transfer paths is narrowed from both ends to the center while gradually decreasing the pitch of the plurality of vertical charge transfer paths, the bending angle becomes maximum in the vertical charge transfer paths at both ends. In the photoelectric conversion block to which this typical mode is applied, the bending angle of the vertical charge transfer path at the end of the block may be 45 degrees or less.

An embodiment of the present invention will be described below with reference to FIGS. (Embodiment 1) FIG. 1 shows a C according to Embodiment 1 of the present invention.
1 shows a configuration of a CD-type solid-state imaging device. In this solid-state imaging device, each of the photoelectric conversion blocks 11, 12,.
3, photodiodes (photoelectric conversion units) 1 are formed in a matrix (matrix, two-dimensional array), and a vertical charge transfer path (VC
CD) 2 extends in the column direction.

In this solid-state imaging device, each of the photoelectric conversion blocks 11, 12,..., 13 and a horizontal charge transfer path (HCCD) 1
7, 18, ... 19, a vertical / horizontal conversion unit (V-H
16) are formed. Each of the horizontal charge transfer paths includes a readout amplifier 31a, 31b,.
c. The read amplifier is disposed closest to the last stage of the horizontal charge transfer path by utilizing the space generated by narrowing the vertical charge transfer path. For this reason, FDA (floating diffusion amplifier)
, The parasitic capacitance of the amplifier can be greatly reduced, and high sensitivity of the amplifier can be realized. The signal charge generated in each photoelectric conversion block region is transferred from the vertical charge transfer path to the read amplifier via the horizontal charge transfer path.

The vertical charge transfer path 2 of this solid-state imaging device is
In each photoelectric conversion block, they are arranged so as to keep the same interval in the horizontal direction. Also at the boundary (seam) portion 3 of each block, the horizontal interval of the vertical charge transfer path is kept constant. Therefore, in this solid-state imaging device, the horizontal intervals of the vertical charge transfer paths are the same in the entire photoelectric conversion region. On the other hand, the intervals between the horizontal charge transfer paths are not constant in the VH converters 14, 15,.

FIG. 2 is an enlarged view near the area P in FIG. In the photoelectric conversion region, the vertical charge transfer paths 2 are arranged so as to keep the pitch A. At an end portion that is in contact with the horizontal charge transfer path, the vertical charge transfer paths 2 are arranged so as to maintain a pitch B (A> B). Here, the pitch B may be narrower than the pitch A by, for example, a range of 40 to 80%. Note that the signal charges are sequentially transferred downward in the drawing in the vertical charge transfer path by applying drive pulses to the transfer electrodes 41 to 54. The transfer electrode is formed of, for example, a polycrystalline silicon film.

If the vertical charge transfer path is sharply bent, transfer deterioration may occur. The preferred bending angle θ is 45 degrees or less. In order to prevent transfer deterioration at a portion where the transfer path is distorted, wiring is preferably performed so that an independent pulse can be applied to this portion. In the embodiment of FIG. 2, it is preferable that at least the electrodes 43 and 44 have an electrode structure provided with a wiring capable of applying a pulse independently of the other electrodes.

As described above, by utilizing the trapezoidal VH conversion section in which the vertical charge transfer path is narrowed down as it approaches the horizontal charge transfer path below in the figure, the free space 3
1d occurs, and the amplifier can be arranged in this empty area. In this solid-state imaging device, the charge transfer direction in the horizontal charge transfer path is the same direction. An amplifier having the same shape is arranged downstream of the transfer path so that the constituent members maintain the same positional relationship (see FIG. 11A).

In this solid-state imaging device, a set of areas through which signals are transmitted, for example, the photoelectric conversion area 11, V-
If the region in the device including the H conversion unit 14, the horizontal charge transfer path 17, and the read amplifier 31a is regarded as one solid-state imaging block, the entire device has a configuration in which the solid-state imaging blocks are extended in the horizontal direction. These solid-state imaging blocks have the same shape and maintain a positional relationship of sequentially moving in parallel with each other. These solid-state imaging blocks can basically have exactly the same shape, except for a wiring pattern that reaches pads connected to the outside on the chip. Therefore, it is extremely advantageous in maintaining the uniformity of the image.

The solid-state imaging device thus obtained is not easily affected by misalignment of a mask in manufacturing a semiconductor or an ion implantation angle. Even when signals are read by a plurality of amplifiers and displayed as one image, signal processing is simple. is there.

In the above embodiment, the respective elements are arranged reasonably sufficiently.
If the amplifier can be arranged even in the area 31e used for forming the above, the area where the amplifier can be arranged can be further expanded. However, this space 31e can be used by the following embodiment.

(Embodiment 2) FIG. 3 shows the configuration of a CCD solid-state imaging device according to Embodiment 2 of the present invention. In this solid-state imaging device, as in the first embodiment, the horizontal charge transfer paths 27, 28... 29 and the photoelectric conversion blocks 21, 22,. Read amplifiers 32a, 32
32... 32c are arranged. Further, between each photoelectric conversion block and the horizontal transfer electrode, V-H converters 24 and 25 are provided.
.. 26 are formed.

In this solid-state imaging device, the vertical charge transfer path 2
The wiring 20 is formed along. The wiring supplies a drive pulse to a lower transfer electrode (not shown) through a contact hole formed as appropriate. The contact holes are formed at predetermined intervals according to the drive pattern to be employed.

As shown in FIG. 4, which is an enlarged view near the region Q in FIG. 3, the wiring 20 is also arranged along the vertical charge transfer path 2 in the VH conversion section. Therefore, it is not necessary to connect the transfer electrodes 41 to 54 in the horizontal direction, and the divided transfer electrodes 45 to 54 can be formed in the VH converter between the solid-state imaging blocks. Therefore, if this mode is used, the area 32e, which was a dead space in the first embodiment, can be used for the arrangement of the read amplifier together with the area 32d.

In the above, the solid-state imaging device of the present invention has been described by exemplifying two embodiments. However, further preferred embodiments and application examples of the device will be further described below.

In the VH converter, the width of the vertical charge transfer path may be the same in order to prevent the so-called narrow channel effect. Referring to FIG. 5A, in this transfer path, the width U ₁ in the photoelectric conversion region is equal to the width V ₁ in the portion connected to the horizontal charge transfer path (U ₁ = V ₁ ).
Furthermore, the width W ₁ are equal at any place on the V-H conversion portion _{(U 1 = W 1 = V} 1).

In order to prevent the narrow channel effect, as shown in FIG. 5B, the width of the transfer path may be increased as approaching from the photoelectric conversion region to the horizontal charge transfer path (U ₂ <W _2). <V _2). Here, an example in which the width of the transfer path is gradually increased is shown, but the width may be gradually increased.

As described above, it is preferable to design the width of the transfer path so that the relationship of U ≦ V is satisfied. More specifically, V is 1.0 to 1.. Five times is preferred.

FIG. 6 shows an example of an imaging system using the solid-state imaging device. The signals read in parallel from the plurality of read amplifiers through the transmission paths 61, 62,... 63 are further different after performing CDS (correlated double sampling), gain adjustment, and ADC (analog-to-digital conversion). A seam portion correction by a read amplifier, serial conversion of parallel data by parallel reading, color processing, and the like are performed, and display on a monitor and accumulation in a memory are performed via a memory controller. This allows
A uniform image without boundaries can be obtained.

FIG. 7 shows a vertical charge transfer path 70 of the solid-state imaging device and vertical transfer electrodes 71, 72,
FIG. 73 is a cross-sectional perspective view of 73. This vertical transfer charge path 70
When viewed from above, a bending point F having a bending angle θ in the transfer path 70 having the width W exists between the transfer electrodes 72 and 73 (FIG. 8A). When the transfer path is bent at a position corresponding to between the electrodes, transfer deterioration is unlikely to occur. On the other hand, if the bending point F of the transfer path 70 is arranged below the transfer electrode 72, transfer deterioration tends to occur below the transfer electrode 72 (FIG. 8B). Although FIG. 7 shows an example in which the transfer electrodes 71 to 73 are formed of two layers of polysilicon films, the electrodes may have three or more layers. Further, the order of stacking the transfer electrodes is not limited to the mode shown in FIG. The transfer electrode 72 may be formed from above the transfer electrodes 71 and 73 on both sides.

However, as shown in FIG. 9, even if the inflection point is formed immediately below the electrode, the transfer packet is, for example, a so-called 2.multidot.
When the transfer is performed by three transfers or the like and the gate length of the transfer electrode 72 is shorter than the electrodes 71 and 73 at both ends, transfer deterioration can be suppressed (L ₁ > L ₂ , L ₃ > L ₂ ). Specifically, if the gate width W is 1 to 3 μm, L ₂ may be shorter than the length L of the other transfer electrodes by about 1 μm. Also, in order to secure the charge capacity, when the gate width W is _{1 to 3} μm, L ₁
And L ₃ is preferably about 3 μm longer than the length L of the other transfer electrodes.

[0035]

As described above, according to the present invention,
It is possible to provide a solid-state imaging device in which signal charges are read at high speed by parallel reading, and it is easy to suppress variations in amplifier input / output characteristics due to misalignment in the mask alignment process in semiconductor manufacturing and implantation angle dependence of impurity doping. Further, since the solid-state imaging blocks including the readout amplifier can be arranged in the same shape and in parallel,
In the case of displaying on one screen, complicated data rearrangement required when reading data with mirror symmetry or the like can be omitted, and thus signal processing becomes easy. Moreover, in this solid-state imaging device, the readout amplifier can be arranged adjacent to the last stage of each horizontal charge transfer path by utilizing the space generated by the narrowing of the vertical charge transfer path, which is advantageous from the viewpoint of increasing the sensitivity of the amplifier. It is.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a solid-state imaging device of the present invention.

FIG. 2 is an enlarged view of a region P in FIG.

FIG. 3 is a diagram showing another configuration example of the solid-state imaging device of the present invention.

FIG. 4 is an enlarged view of a region Q in FIG. 2;

FIGS. 5A and 5B are plan views illustrating the line width of a vertical charge transfer path.

FIG. 6 is a block diagram illustrating a configuration example of an imaging system according to the present invention.

FIG. 7 is a partially cutaway perspective view showing a vertical charge transfer path of the solid-state imaging device of the present invention and a structure above the vertical charge transfer path.

FIGS. 8A and 8B are plan views showing examples of the vicinity of a bent portion of a vertical charge transfer path of the solid-state imaging device of the present invention.

FIG. 9 is a plan view showing another example of the vicinity of the bent portion of the vertical charge transfer path of the solid-state imaging device of the present invention.

FIG. 10 is a diagram illustrating a configuration example of a conventional solid-state imaging device.

FIGS. 11A and 11B are diagrams showing differences in amplifier shapes due to alignment and ion implantation angle shifts. FIG. 11A shows a pair of transistors having a positional relationship due to parallel movement, and FIG. A pair of transistors having a positional relationship of (symmetric).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photodiode (photoelectric conversion part) 2 Vertical charge transfer path (VCCD) 3 Block boundary part 11, 12, 13, 21, 22, 23 Photoelectric conversion block 14, 15, 16, 24, 25, 26 Vertical / horizontal conversion part (V-H converter) 17, 18, 19, 27, 28, 29 Horizontal charge transfer path (HCCD) 20 Wiring 31a-c, 32a-c Readout amplifier 41-54 Transfer electrode 70 Vertical charge transfer path (VCCD) 71 , 72,73 Vertical transfer electrode

Continuing on the front page (72) Inventor Yamaguchi ▲ Takumi 1006 Kazuma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Terms (reference) 4M118 AA03 AA10 AB01 BA10 CA02 DA03 DA16 DA24 DB01 DD04 FA06 FA44 5C024 CY49 GX03 GY01 HX18 HX23 HX60 JX21

Claims (13)

[Claims] A photoelectric conversion region including a plurality of photoelectric conversion units arranged in a matrix along a vertical direction and a horizontal direction, and a plurality of vertical charge transfer paths extending along a column of the photoelectric conversion units; A solid-state imaging device including a horizontal charge transfer path that receives signals from a plurality of vertical charge transfer paths, wherein the plurality of vertical charge transfer paths are arranged at a pitch A in the photoelectric conversion region in the horizontal direction. A solid-state imaging device, wherein a signal input to a horizontal charge transfer path is arranged at a pitch B smaller than the pitch A. 2. A horizontal charge transfer path for receiving a signal from the vertical charge transfer path in each of the divided areas along the vertical direction, the read charge amplifier further comprising a read amplifier for receiving a signal from the horizontal charge transfer path. The solid-state imaging device according to claim 1, further comprising a readout amplifier. 3. The horizontal amplifier according to claim 2, wherein a horizontal charge transfer path for receiving a signal from a vertical charge transfer path in the area and a readout amplifier are arranged at intervals equal to or less than the width of the area into which the photoelectric conversion region is divided. Solid-state imaging device. 4. A plurality of solid-state imaging blocks having substantially the same shape are defined as an area obtained by dividing a photoelectric conversion region, a horizontal charge transfer path for receiving a signal from the area, and a readout amplifier as one solid-state imaging block. The solid-state imaging device according to claim 2, wherein the solid-state imaging device is arranged along. 5. The solid-state imaging device according to claim 2, wherein the vertical charge transfer paths are arranged at a pitch A in the horizontal direction even at a boundary between the divided areas of the photoelectric conversion region. 6. The solid according to claim 1, wherein the width of the vertical charge transfer path in the horizontal direction is substantially constant from the end of the photoelectric conversion region to the end of the horizontal charge transfer path. Imaging device. 7. The method according to claim 1, wherein the width of the vertical charge transfer path in the horizontal direction is gradually or gradually increased from the end of the photoelectric conversion region to the end of the horizontal charge transfer path. The solid-state imaging device according to any one of the preceding claims. 8. A plurality of transfer electrodes wired so that a transfer drive pulse can be applied to at least a bent portion of the vertical charge transfer path independently of other portions of the vertical charge transfer path,
The solid-state imaging device according to claim 1, wherein the solid-state imaging device is arranged on the vertical charge transfer path. 9. The solid-state imaging device according to claim 1, wherein a plurality of transfer electrodes are arranged such that a bent portion of the vertical charge transfer path is located below between the transfer electrodes. 10. A bent portion of a vertical charge transfer path is located below a predetermined transfer electrode, and a transfer path length to which a transfer drive pulse is applied by the predetermined transfer electrode is adjacent to the predetermined transfer electrode. The solid-state imaging device according to claim 1, wherein the length of the transfer path to which the transfer drive pulse is applied by the transfer electrode is shorter. 11. A wiring electrically connected to a plurality of transfer electrodes for applying a transfer drive pulse to a vertical charge transfer path, at least from a photoelectric conversion region along the vertical charge transfer path to the vertical charge transfer path. The solid-state imaging device according to any one of claims 1 to 10, wherein the solid-state imaging device is arranged over a region in which is arranged in a region less than the pitch A in the horizontal direction. 12. The vertical charge transfer path having a maximum bending angle, wherein the bending angle is 45 degrees or less.
The solid-state imaging device according to any one of the above. 13. A solid-state image pickup device according to claim 2, and an output obtained from a readout amplifier in each section of the solid-state image pickup element are combined to correct an image of a joint portion corresponding to a boundary portion of each section. And a signal processing unit for displaying one image.