JPS6221019Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Technical field of the invention This invention is a charge transfer device (Charge Coupled Device).
The present invention relates to a solid-state imaging device using an interline transfer method, and particularly relates to an improvement of a solid-state imaging device using an interline transfer method.

(b) Background of the technology Since solid-state imaging devices use semiconductors, they are small and lightweight, have low power consumption, and have the potential for lower prices due to mass production effects.
Since image signals are read out at regular time intervals, there is no inaccuracy related to figure distortion in the photoelectric conversion process, and the device has features such as low afterimages and high S/N, making it ideal for image pickup tubes. Instead, it is being put into practical use. A solid-state imaging device using an interline transfer method using a charge transfer element is well known as a type of such a fixed imaging device.

(c) Prior Art and Problems Normally, a solid-state imaging device using an interline transfer method has a plurality of photoelectric conversion elements arranged in a matrix on the same semiconductor substrate 1 as shown in FIG. A charge transfer vertical register 4 including a plurality of light receiving sections 2 configured as pixels, and a plurality of charge transfer electrodes arranged in a column parallel to and adjacent to each column of the light receiving sections 2 via transfer gate electrodes 3, respectively; It consists of a charge transfer horizontal register 5 connected to one end of each vertical register 4. In operation, the signal charges accumulated in each of the light receiving sections 2 according to the amount of incident light are transferred to the corresponding vertical registers 4 via, for example, the transfer gate 3. After the signal charge is transferred to the vertical register 4, the transfer gate 3 is closed and the next signal charge is accumulated in each of the light receiving sections 2. On the other hand, the signal charges transferred to each of the vertical registers 4 are sequentially transferred in parallel in the vertical direction and transferred to the horizontal register 5. In the horizontal register 5, signal charges are sequentially transferred in the horizontal direction for each horizontal line of each vertical register 4, and are taken out from the output terminal 6 as an imaging output. In FIG. 1, arrows indicate the direction of signal charge transfer.

By the way, in a conventional solid-state imaging device having such a configuration, as shown in FIG. The structure is such that one bit of the charge transfer electrodes 21 corresponds to four electrodes. Therefore, the electrode length L of the charge transfer electrode 21 in the charge transfer direction becomes long, resulting in a disadvantage that the transfer efficiency deteriorates during high-speed transfer driving and the resolution decreases.

(d) Purpose of the invention In order to eliminate the above-mentioned conventional drawbacks, the present invention shortens the electrode length L of the transfer electrode of the charge transfer element used as a vertical register to transfer the signal charge accumulated in each light receiving part. It is an object of the present invention to provide a novel solid-state imaging device that prevents deterioration of charge transfer efficiency and improves resolution.

(e) Structure of the invention According to the invention, the object is to provide a plurality of photoelectric conversion elements arranged in a matrix on a semiconductor substrate, and to provide transfer gate electrodes in parallel and adjacent to each row of the photoelectric conversion elements. A charge transfer vertical register in which a plurality of charge transfer electrodes are arranged in a column through a charge transfer vertical register, and signal charges from each element transferred in the vertical direction by the vertical register are sequentially transferred in the horizontal direction for each horizontal line of the vertical register. A device comprising a charge transfer horizontal register for transferring and reading data, characterized in that charge transfer electrodes of the charge transfer vertical register corresponding to each unit photoelectric conversion element are arranged oppositely for at least two bits. This is achieved by providing a solid-state imaging device that achieves this goal.

(f) Embodiments of the invention Examples of the invention will be described below in detail with reference to the drawings.

FIG. 3 is an enlarged plan view of essential parts of an embodiment of the solid-state imaging device according to the present invention. In the figure, 31 is a semiconductor substrate, and 32 is a plurality of photoelectric conversion elements arranged in a matrix, that is, a plurality of light receiving parts each configured as one pixel, which are adjacent in parallel to each row of the light receiving parts 32. In the present invention, each electrode length L of the charge transfer vertical register 34 corresponding to each unit light receiving section 32, in this case, the four-phase drive charge transfer electrode 35, is halved via the transfer gate electrode 33. In short, for example, eight transfer electrodes for two bits are arranged opposite each other, and one end of each charge transfer vertical register 34 in this structure is connected to a charge transfer horizontal register (not shown) as in the conventional case. It is being And each light receiving section 3
By vertically transferring the signal charge photoelectrically converted and accumulated in step 2 by the charge transfer electrode 35 for 2 bits of the charge transfer vertical register 34 through the transfer gate 33, deterioration of the signal charge transfer efficiency is prevented. This improves the resolution.

In the above embodiment, an example was explained in which a four-phase drive charge transfer electrode is used in the charge transfer vertical register, but the present invention is not limited to this, and for example, a three-phase drive charge transfer electrode may be used. A similar effect can be obtained when using the same method. Furthermore, the number of bits of the charge transfer electrodes of the charge transfer vertical register corresponding to each unit light receiving section is not limited to 2 bits, but the length of the transfer electrodes can be further shortened as necessary, and multiple bits of 2 or more bits can be arranged facing each other. Needless to say, it can be arranged and implemented.

(g) Effect of the invention As is clear from the above explanation, according to the structure of the solid-state imaging device according to the invention, the electrode length of the charge transfer electrode of the charge transfer vertical register corresponding to each unit light receiving section can be shortened. By arranging two or more bits of transfer electrodes facing each other, deterioration of the transfer efficiency of the signal charges to be transferred is prevented, and the resolution is increased, so that a reliable high-resolution solid-state imaging device can be obtained. Therefore, it is extremely advantageous to apply to solid-state imaging devices using various interline transfer methods.

[Brief explanation of the drawing]

1 and 2 are block diagrams and enlarged plan views of essential parts for explaining a solid-state imaging device using a conventional interline transfer method, and FIG. 3 shows a solid-state imaging device using an interline transfer method according to the present invention. FIG. 2 is an enlarged plan view of main parts showing one embodiment. In the drawing, 31 is a semiconductor substrate, 32 is a light receiving section, 33 is a transfer gate electrode, 34 is a charge transfer vertical register, and 35 is a four-phase drive charge transfer electrode.

Claims (1)

[Scope of utility model registration request] A charge transfer vertical register comprising a plurality of photoelectric conversion elements arranged in a matrix on a semiconductor substrate, and a plurality of charge transfer electrodes arranged in parallel and adjacent to each column of the photoelectric conversion elements via transfer gate electrodes. and a charge transfer horizontal register that sequentially transfers and reads signal charges from each element vertically transferred by each vertical register in the horizontal direction for each horizontal line of the vertical register. A solid-state imaging device characterized in that charge transfer electrodes of charge transfer vertical registers corresponding to each of the unit photoelectric conversion elements are arranged oppositely for at least two bits.