JPH08288494A - Charge transfer device and solid-state image pickup device - Google Patents

Abstract

PURPOSE: To provide a charge transfer device which can restrain propagation delay of a transfer clock at a low cost by simplifying manufacturing. CONSTITUTION: In a charge transfer device of two-phase driving, two-phase Al wiring patterns 13, 14 are formed in a dual loop in the same layer, and a connection point of the Al wiring pattern 13 of an inner first phase (Hϕ1) and a drive input terminal 21 are wired by a polysilicon wiring pattern 17. Meanwhile, a polysilicon wiring pattern 23 with approximately the same resistance value as the polysilicon wiring pattern 17 is interposed between a connection point of the Al wiring pattern 14 of an outer second phase (Hϕ2) and a drive input terminal 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge transfer device and a solid-state image pickup device using the same, and more particularly, to a plurality of transfer electrodes arranged above a transfer channel along the transfer direction and at both ends in the array direction. The present invention relates to a charge transfer device configured to supply and drive a transfer clock from the side and a solid-state imaging device using the charge transfer device.

[0002]

2. Description of the Related Art In a two-phase drive horizontal transfer register of a CCD area sensor, which is a solid-state image pickup device, when a plurality of transfer electrodes arranged above a transfer channel along the transfer direction are driven, the conventional method is as follows. As shown in FIG. 5, two-phase transfer clocks Hφ1 and Hφ2 are supplied and driven from one end side in the arrangement direction of the two-phase transfer electrodes 51 and 52 arranged alternately, that is, so-called one-side drive. In the case of this one-sided drive, the transfer electrodes 51 of the first phase are connected to each other A
an Al (aluminum) wiring pattern 53 and an Al wiring pattern 54 for connecting the second-phase transfer electrodes 52 to each other;
These Al wiring patterns 53 and 54 and the drive input terminal 5
Since the Al wiring patterns 57 and 58 connecting the wiring patterns 5 and 56 do not cross each other, the Al wiring patterns 53 and 54,
57 and 58 are formed as the same layer.

[0003]

As described above, according to the prior art in which the transfer clocks Hφ1 and Hφ2 are supplied to the two-phase transfer electrodes 51 and 52 from one side in the arrangement direction to drive them, Since the wiring pattern can be configured by one layer, it has an advantage that the structure is simple, but on the other hand, the propagation delay is large at the end portion on the side for supplying the transfer clocks Hφ1 and Hφ2 and the end portion on the opposite side, and at a high frequency. When driven, there is a problem that it is not suitable for high speed driving because the driving amplitude is reduced or the phase is shifted at the end of the horizontal transfer register.

As another conventional example, as shown in FIG. 6, an Al wiring pattern 63 connecting the first-phase transfer electrodes 61 to each other and an Al wiring pattern connecting the second-phase transfer electrodes 62 to each other. There is also known a so-called double-sided drive in which 64 is formed in a loop shape and two-phase transfer clocks Hφ1 and Hφ2 are supplied and driven from both ends in the arrangement direction of the transfer electrodes 61 and 62. In the case of this double-sided drive, the outside A
A connecting the wiring pattern 64 and the drive input terminal 66
The l wiring pattern 68 does not cross other Al wiring patterns, but the inner Al wiring pattern 63
Wiring pattern 67 for connecting the drive input terminal 66 with the
As for the above, since the outer Al wiring pattern 64 and the portion A cross, the Al wiring pattern 63 and the Al
The wiring pattern 64 and the wiring pattern 64 are formed in two layers, and the space between them is partitioned by an insulating film.

In the conventional technique in which both sides are driven as described above,
Since the propagation delay of the transfer clocks Hφ1 and Hφ2 during driving can be suppressed, this structure is advantageous when driven at high speed. However, on the other hand, since the Al wiring pattern has a two-layer structure, the manufacturing becomes complicated and the cost becomes high. If this is to be realized with a single layer, either Hφ1 or Hφ2 wiring pattern of part A must be Al.
It must be formed of a conductor other than polysilicon, for example, polysilicon. However, when the wiring pattern of Hφ2 is made of polysilicon, the voltage waveforms given to the left and right of the horizontal transfer register in the figure are different, which adversely affects the charge transfer. Further, if the wiring pattern of Hφ1 is formed of polysilicon only, the transfer clocks Hφ1 and Hφ2
Will result in a difference in phase and amplitude.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a charge transfer device capable of suppressing the propagation delay of a transfer clock at a low cost at a simple manufacturing process. To provide.

[0007]

According to the present invention, two-phase transfer clocks are supplied from both ends in the array direction to two-phase transfer electrodes arrayed in a plurality along the transfer direction above the transfer channel. In a charge transfer device configured to perform transfer driving by means of transfer driving, the connection point of the inner conductor wiring pattern of the two-phase conductor wiring pattern and the drive input terminal of one phase are formed as a layer different from the conductor wiring pattern. The first polysilicon wiring pattern electrically connected to the first polysilicon wiring pattern has substantially the same resistance value as the first polysilicon wiring pattern, and the connection point of the outer conductor wiring pattern of the two-phase conductor wiring pattern and the other phase. Second for electrically connecting to the drive input terminal of
And the polysilicon wiring pattern.

[0008]

In the charge transfer device having the above structure, the structure is simplified by forming the two-phase conductor wiring patterns in the same layer. In this wiring structure, the conductor wiring pattern inside the double loop and the drive input terminal of one phase cannot be wired in the same layer, so that the first polysilicon wiring pattern forms the wiring. On the other hand, the outer conductor wiring pattern of the double loop and the drive input terminal of the other phase are wired by the second polysilicon wiring pattern having substantially the same resistance value as that of the first polysilicon wiring pattern. The resistance value between each of the phase drive input terminals and each connection point of the two-phase conductor wiring pattern is substantially the same. As a result, the phase and amplitude conditions of the two-phase transfer clocks can be made substantially equal.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a plan pattern diagram showing an embodiment of the present invention. In FIG. 1, above the transfer channel 10 for transferring the signal charge (in the front direction with respect to the paper surface).
The transfer electrodes 11 and 2 of the first phase along the transfer direction.
A large number of transfer electrodes 12 of the phase are arranged alternately at regular intervals. First-phase and second-phase transfer electrodes 11 and 12
Is formed of polysilicon in a two-layer structure. In order to supply two-phase transfer clocks Hφ1 and Hφ2 to the transfer electrodes 11 and 12 from both ends in the arrangement direction, a loop-shaped 1 extending along the arrangement direction on one side of the electrode arrangement. Phase (Hφ1) and second phase (Hφ2) conductor wiring patterns, for example, Al wiring patterns 13 and 14
However, they are formed in a double loop in the same layer so that the Al wiring pattern 13 of the first phase is inside.

This double loop Al wiring pattern 13,
In the straight line portion on one side of 14, the inner Al wiring pattern 13 is electrically connected to each of the first-phase transfer electrodes 13 at the contact portions 15, and the outer Al wiring pattern 1 is formed.
Reference numeral 4 is electrically connected to each of the transfer electrodes 14 of the second phase through contact portions 16. Further, in the straight line portion on the other side, the inner Al wiring pattern 13 is electrically connected to one end of the polysilicon wiring pattern 17 by a contact portion 18. The polysilicon wiring pattern 17 is provided so as to straddle the outer Al wiring pattern 14, and the other end is electrically connected to the Al wiring pattern 19 through a contact portion 20. The Al wiring pattern 19 is wired to the drive input terminal 21 which receives the transfer clock Hφ1 of the first phase as an input.

FIG. 2 is an X view seen from the direction of the arrow in FIG.
It is a sectional view taken along the line -X '. In FIG. 2, the outer second phase (Hφ) is formed on the polysilicon wiring pattern 17.
The Al wiring pattern 14 of 2) is formed in the direction perpendicular to the paper surface with the insulating film 27 interposed therebetween. The inner first-phase (Hφ1) Al wiring pattern 13 is electrically connected to one end of the polysilicon 17 through a contact portion 18, and the other end has an Al wiring provided outside the loop. The pattern 19 is electrically connected via the contact portion 20. Here, the resistance value R1 of the polysilicon wiring pattern 17 has a film thickness t1, a width W1 and a length L1 (see FIG. 1).
). It is well known that polysilicon is doped with a large amount of impurities such as phosphorus (P) to reduce the resistance.

Referring again to FIG. 1, the outer Al wiring pattern 14 in the straight line portion on the other side of the double loop Al wiring patterns 13 and 14 has the second-phase transfer clock Hφ2.
Is extended in the direction of the drive input terminal 22 for inputting. A tip portion of the extending portion 14a is electrically connected to one end portion of the polysilicon wiring pattern 23 by a contact portion 24. The other end of the polysilicon wiring pattern 23 is electrically connected to an Al wiring pattern 25 wired to the drive input terminal 22 of Hφ2 by a contact portion 26. Here, the film thickness t2, the width W2 and the length L2 of the polysilicon wiring pattern 23 are selected so that the resistance value R2 thereof is substantially equal to the resistance value R1 of the polysilicon wiring pattern 17.

In the charge transfer device having the above structure, as is clear from FIG. 3 showing an equivalent circuit thereof, the drive input terminal 21 for inputting the transfer clock Hφ1 of the first phase and the inner looped Al wiring pattern 13 are provided. A polysilicon wiring pattern 17 having a resistance value R1 is interposed between the connection point P and the connection point P. On the other hand, a polysilicon wiring pattern 23 having a resistance value R2 is interposed between the drive input terminal 22 which receives the transfer clock Hφ2 of the second phase and the connection point Q of the outer loop Al wiring pattern 14. become. Here, the resistance value R1 of the polysilicon wiring pattern 17 and the resistance value R2 of the polysilicon wiring pattern 23 are set so as to have a relationship of R1≈R2 as described above.

As described above, the two-phase Al wiring patterns 13 and 14 are formed in the same layer by a double loop, and the connection point P of the inner first-phase (Hφ1) Al wiring pattern 13 and the drive input are formed. While the terminal 21 is wired by the polysilicon wiring pattern 17, a resistance value substantially the same as that of the polysilicon wiring pattern 17 is provided between the connection point Q of the outer second-phase (Hφ2) Al wiring pattern 14 and the drive input terminal 22. By interposing the polysilicon wiring pattern 23 having the above, the double-sided driving can be realized by one layer of Al wiring. Therefore, the wiring structure is simplified, and the conventional one-layer Al wiring process can be realized without additional steps, which facilitates manufacturing.

Further, each of the two-phase drive input terminals 21 and 22 and each of the connection points P of the two-phase conductor wiring patterns 13 and 14 are connected.
Since the resistance value between Q and Q is almost the same, the conditions of the phase and amplitude of the two-phase transfer clocks Hφ1 and Hφ2 are almost equal. That is, the driving conditions of both phases are almost equal. Therefore, both-side driving suitable for high-speed driving can be realized without adversely affecting the charge transfer.

Next, the charge transfer device having such a structure is connected to CC
A case where the D area sensor is used as a two-phase driving horizontal transfer register will be described. FIG. 4 shows an example of the structure of an interline transfer type CCD area sensor. FIG.
In the horizontal direction (horizontal direction in the figure) and in the vertical direction (vertical direction in the figure), a large number of photosensors 41 for converting incident light into signal charges having a charge amount according to the light amount and accumulating the signal charges. An image pickup section 43 is configured by a plurality of vertical transfer registers 42 arranged in each vertical column of the photosensors 41 and vertically transferring the signal charges read from each photosensor 41.

In this image pickup section, the signal charges photoelectrically converted by the photosensor 41 are instantaneously read out to the vertical transfer register 42 during a part of the vertical blanking period. The vertical transfer register 42 transfers the signal charges read from the photosensor 41 to the horizontal transfer register 44 by driving the signal charges in four phases, for example, in a part of the horizontal blanking period, corresponding to one scanning line. To do. The horizontal transfer register 44 is of a two-phase drive type and is configured by using the charge transfer device of the above-described embodiment.

For the two-phase driving of the horizontal transfer register 44, as described above, the two-phase transfer clocks Hφ1 and Hφ are used.
Since the two driving conditions are almost the same and the double-sided driving suitable for high speed driving is used, the signal charges for one scanning line transferred from the imaging unit 43 can be favorably horizontally transferred. A charge detection unit 45 having, for example, a floating diffusion amplifier configuration is provided at the subsequent stage of the horizontal transfer register 44. The charge detection unit 45 detects the signal charge transferred by the horizontal transfer register 44 and converts it into a signal voltage. This signal voltage is derived as a CCD output via a buffer 46 including a source follower circuit.

In this example, the charge transfer device according to the present invention is applied to the horizontal transfer register of the CCD area sensor, but the present invention is not limited to this, and is also applied to the transfer register of the CCD linear sensor. It is possible. Furthermore, it is not limited to the application to the solid-state imaging device,
The transfer register of the delay element can be similarly applied.

[0020]

As described above, according to the present invention,
A two-phase conductor wiring pattern is formed in a double loop on the same layer, and the connection point of the inner conductor wiring pattern and the drive input terminal of one phase are wired by the first polysilicon wiring pattern, while the outer side The second polysilicon wiring pattern having substantially the same resistance value as that of the first polysilicon wiring pattern is interposed between the connection point of the conductor wiring pattern and the drive input terminal of the other phase. Of 1
Since it can be realized in the layer wiring process without additional steps, it is easy to manufacture and the cost can be reduced, and since the driving conditions of both phases are almost the same, both-side driving suitable for high-speed driving adversely affects the charge transfer. Can be realized without any.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line XX ′ in the direction of the arrow in FIG.

FIG. 3 is an equivalent circuit diagram according to an embodiment.

FIG. 4 is a configuration diagram showing an example of a CCD area sensor to which the present invention is applied.

FIG. 5 is an equivalent circuit diagram according to a conventional example.

FIG. 6 is an equivalent circuit diagram according to another conventional example.

[Explanation of symbols]

 10 Transfer Channel 11 1st Phase Transfer Electrode 12 2nd Phase Transfer Electrode 13 1st Phase Al Wiring Pattern 14 2nd Phase Al Wiring Pattern 17 First Polysilicon Wiring Pattern 21 1st Phase Drive Input Terminal 22 Second-phase drive input terminal 23 Second polysilicon wiring pattern

Claims (2)

[Claims] 1. A charge configured to supply and drive a two-phase transfer electrode by supplying a two-phase transfer clock from both ends in the arrangement direction to a plurality of two-phase transfer electrodes arranged above the transfer channel along the transfer direction. A transfer device, wherein a two-phase conductor wiring pattern formed in a double loop on the same layer and electrically connected to each of the two-phase transfer electrodes, and the two-phase transfer clock are input respectively. And a connection point of the inner conductor wiring pattern of the two-phase conductor wiring pattern formed as a layer different from the same layer and one of the two drive input terminals. And a connection point of the outer conductor wiring pattern of the two-phase conductor wiring pattern, which has substantially the same resistance value as the first polysilicon wiring pattern Charge transfer device is characterized in that a second polysilicon wiring pattern for electrically connecting the other of the two drive input terminal. 2. A plurality of photosensors, an imaging section for photoelectrically converting incident light by these photosensors, and a plurality of two-phase transfer electrodes arranged above the transfer channel along the transfer direction. A two-phase drive charge transfer unit that transfers and drives the signal charges sent from the imaging unit to the two-phase transfer electrodes by two-phase transfer clocks supplied from both ends in the arrangement direction. The charge transfer unit includes a two-phase conductor wiring pattern formed in a double loop on the same layer and electrically connected to each of the two-phase transfer electrodes, and the two-phase transfer clock. And two drive input terminals each of which is an input, and one of the two drive input terminals and a connection point of an inner conductor wiring pattern of the two-phase conductor wiring patterns formed as a layer different from the same layer. A first polysilicon wiring pattern for electrically connecting the two, and a connection point of the outer conductor wiring pattern of the two-phase conductor wiring pattern, which has substantially the same resistance value as that of the first polysilicon wiring pattern. A solid-state image pickup device comprising: a second polysilicon wiring pattern for electrically connecting the other of the two drive input terminals.