JPS646590B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a charge transfer device, and more specifically to an improvement in the arrangement of driving busbars in a charge transfer device having a time delay and integration function, such as those used in solid-state imaging devices.

In recent years, solid-state imaging devices configured by a combination of a light receiving element and a charge transfer device for signal processing have been developed and put into practical use. Such a solid-state imaging device has a light-receiving element array formed on a semiconductor substrate, a charge transfer device for signal processing formed on the semiconductor substrate, and these are combined into an integrated device. The signal from the light receiving element, which has been photoelectrically converted in accordance with the amount of incident light, is processed by a charge transfer device and output as a time-series image signal.

The signal-to-noise ratio (S/N) of such an imaging device
A method called time delay integration (TDI) has been adopted to improve image quality and obtain good image signals. As is well known, in this TDI method, an optical image of an object to be imaged is moved in the column direction of an array in which photodetectors are arranged in a matrix, and each imaged signal on the column is photoelectrically converted with a time difference into the optical image. The image signal is inputted to each input section of the charge transfer unit for TDI, which performs time-delay integration in synchronization with the moving speed, and is integrated. According to this method, the number of light-receiving elements in the column direction is n. If so, the S/N will be improved by a factor of √.
Therefore, a good image signal can be obtained by inputting the output from the TDI charge transfer unit of each column to another CCD and extracting a time-series image signal.

Incidentally, in a charge transfer device having such a TDI function, driving busbars are arranged as shown in FIG. In the figure, A is a light-receiving element array, and the array A has one light-receiving element.
A to 1d, 2a to 2d, etc. are arranged in a matrix. Further, B is a charge transfer device having a TDI function, and the charge transfer device B is composed of a plurality of charge transfer units for TDI such as U1 and U2.
The charge transfer units U1 and U2 have input sections 1a'' to 1d'' and 2a'' to 2d'' with different delay times, and these input sections are connected to input wirings 1a' to 1d' and 2a' to 2d'. Light receiving elements 1a to 1d and 2a to 2
connected to d. In addition, each of the TDI charge transfer units U1 and U2 has a charge transfer electrode 111.
431 and 112 to 432 are arranged, and each of these transfer electrodes has a stepped shape whose width is gradually increased for each bit, and is regularly connected to the drive bus bars 11 to 432.
13 and 21 to 23 are commonly connected and led out. In this method of arranging the driving busbars, if the charge transfer device B is to be formed at high density, the area for arranging the driving busbars becomes narrow, and the busbars and contact holes of minute dimensions are inevitably required. As a result, problems such as short circuits between bus bars and disconnection of bus bars are likely to occur, which is a factor that causes a decrease in the manufacturing yield of the device. In the figure, a solid arrow P indicates the direction of movement of the optical image, and T indicates the direction of charge transfer.

On the other hand, as a method to solve the above-mentioned problem, as shown in Fig. 2, each TDI charge transfer unit U1, U
Connecting wires 11' to 4 connect the electrodes of the same rank to each other.
3' may be considered, but in this case, the input wirings 2a' to 2c' and the connection lines 11' to 33' would intersect, and as a result, unnecessary signals from the connection lines would be induced in the input wirings. This causes deterioration of electrical characteristics such as coupling noise, and also causes problems such as disconnection due to steps at intersections. Furthermore, the second
Components in the figure that are equivalent to those in FIG. 1 are given the same reference numerals.

The present invention has been made in view of the above-mentioned points, and its purpose is to facilitate the arrangement of drive busbars and eliminate intersections with input wiring, thereby improving the manufacturing yield and electrical characteristics of the device. The purpose of the present invention is to provide a charge transfer device having a time delay integration function, which is characterized by a plurality of charge transfer devices having different delay times connected to each light receiving element in each column of a light receiving element array arranged in a matrix. In a charge transfer device comprising a plurality of time delay integration charge transfer units each having an input section, two adjacent charge transfer units among the time delay integration charge transfer units are made into a pair, and the respective charge transfer units are arranged in the same order. charge transfer electrodes are commonly disposed, and each charge transfer electrode is regularly led out through a common bus bar.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a top view of a main part model for explaining the arrangement of driving busbars of the charge transfer device for time delay integration according to the present invention, and the same parts as in FIG. 1 are given the same reference numerals. In the figure, B is a charge transfer device according to the present invention, and the charge transfer device B is U1, U
The TDI charge transfer units U1 and U2 are composed of a plurality of TDI charge transfer units U1 and U2, which are connected to a plurality of input units 1a'' to 1 with different delay times.
d'' and 2a'' to 2d'', and each of these input sections is arranged at each step of the stepped unit and connected to the input wiring 1.
a' to 1d' and 2a' to 2d' are light receiving elements 1a to 1d.
and 2a to 2d. This point is the same as the conventional charge transfer device, but the difference is as follows. In other words, the two adjacent TDI charge transfer units U1 and U2 are configured as a pair back to back, and the charge transfer electrodes of each of the charge transfer units U1 and U2 are disposed in common, and each of the charge transfer electrodes is arranged in common. They are regularly led out in a direction that intersects the transfer electrodes through a common bus bar. To explain these points in more detail, TDI charge transfer units U1 and U2
The first stage charge transfer electrodes are 511, 52.
1,531, and the first charge transfer electrode 511 of that stage is common to the TDI charge transfer units U1 and U2, and the second and third charge transfer electrodes 521 and 531 of the same stage are also the same. It has become common. Furthermore, the second, third and fourth stage charge transfer electrodes 611 to 631, 711 to
731 and 811 to 831 are similarly provided in common to the TDI charge transfer units U1 and U2. And the first charge transfer electrode 511 of each stage,
The second charge transfer electrodes 521, 621, 721, 831 of each stage are commonly connected to the drive bus 52, and are led out by being commonly connected to the drive bus 51. The third charge transfer electrode 531, 631, 731, 8 in
31 are commonly connected to and led out from the drive bus 53.

In this way, by configuring two adjacent TDI charge transfer units as a pair and disposing the charge transfer electrodes of the same order in each of these charge transfer units in common, the width of each charge transfer electrode, that is, the third The horizontal length in the figure is twice that of the conventional one.
Therefore, the space for arranging the driving busbars is doubled, and the busbars 51, 52, and 53 can be easily arranged without extremely reducing the dimensions, and the space for arranging the busbars is narrower than in the past. This makes it possible to prevent problems such as bus disconnections and short circuits that would otherwise occur due to this. Furthermore, as is clear from the figure, there is no intersection between the input wiring and the drive bus, and the problems that conventionally occur due to such intersections, such as deterioration of electrical characteristics such as coupling noise, and disconnection of wiring, are simultaneously eliminated. can do.

Although not shown, the charge transfer electrodes in the same order in the final stage of each TDI charge transfer unit configured as a pair as described above, that is, adjacent to the right side of the charge transfer electrodes 811, 821, and 831 in FIG. It is also possible to connect the charge transfer electrodes disposed in parallel rows with a common bus bar in a row, or to connect the charge transfer electrodes disposed adjacent to each other with a common bus bar as described above. Alternatively, it is also possible to provide charge transfer electrodes common to all units and to derive busbars from each of these electrodes.

As is clear from the above description, according to the present invention, it is possible to easily arrange a drive bus of a charge transfer device having a time delay integration function used in a solid-state imaging device, and to connect input wiring and drive bus. This has the advantage that it is possible to prevent deterioration of electrical characteristics such as disconnection, short circuit, and coupling noise of the drive bus bar, and to improve the yield and performance of the device.

[Brief explanation of drawings]

1 and 2 are top views of principal parts for explaining the arrangement of driving bus bars in a conventional charge transfer device for time delay integration, and FIG. 3 is a drive of a charge transfer device for time delay integration according to the present invention. FIG. 2 is a top view of a main part model for explaining the arrangement of busbars. 1a to 1d, 2a to 2d: light receiving element, 1a' to 1
d', 2a'~2d': Input wiring, 1a''~1d'', 2a''~
2d'': Input section, 511-531, 611-63
1,711 to 731, 811 to 831: charge transfer electrodes, 51, 52, 53: bus bars, A: light receiving element array, B: charge transfer device, U1, U2: charge transfer unit for time delay integration.

Claims (1)

[Claims] 1 A charge comprising a plurality of charge transfer units for time delay integration each having a plurality of input sections having mutually different delay times and connected to each light receiving element in each column of a light receiving element array arranged in a matrix. In the transfer device, each of the charge transfer units for time delay integration has a stepped electrode formed such that an input section for each light receiving element in a corresponding light receiving element array row is sequentially disposed at a step for each bit. Two stepped charge transfer units corresponding to two adjacent rows of light receiving element arrays are arranged back-to-back as a pair, and the charge transfer electrodes of the charge transfer units in the same order are connected to each other. What is claimed is: 1. A charge transfer device characterized in that charge transfer electrodes that are commonly disposed and are common to both units are led out regularly through a common bus bar in a direction that intersects the transfer electrodes.