Charge coupled device

Abstract: A charge coupled device (CCD) of a frame interline transfer type comprises a plurality of picture elements aligned in the vertical direction. Rows of aligned picture elements are arranged parallel and adjacent to each other. Polysilicon electrodes (10,11,12) extending in the horizontal direction are arranged on a substrate (9) covered with an insulating layer (14) and used as electrodes for vertical transfer of signal charges. Metal wiring films (13) extending in the vertical direction are arranged parallel and traverse the polysilicon electrodes covered with the insulating layer. The metal wiring films are used as electrodes for applying a clock pulse for vertical transfer of signal charges to the polysilicon electrodes. First, second and third openings (13A,B,C) are formed through the insulating layer such that the metal wiring films may contact the first, second and third polysilicon electrodes, respectively.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a charge coupled device (CCD) of a non-interlacing type which performs frame interline transfer (FIT) in accordance with the precharacterizing part of claim 1. Such a charge coupled device is known e.g. from JP-A-56 087379 and PAJ thereof. Further known charge coupled device of this type are disclosed in JP-A-63 275164 and PAJ thereof and JP-A-60 038869 and PAJ thereof. The principle of the above known CCD will be explained in the following in view of figs. 1 - 4. SUMMARY OF THE INVENTION It is an object of the present invention to provide a non-interlacing charge coupled device (CCD) which can perform frame interline transfer (FIT). In order to accomplish this object there is provided a non-interlacing charge coupled device of a frame interline transfer (FIT) type comprising: a plurality of picture elements being aligned in the vertical direction, rows of said vertically aligned picture elements being arranged parallel and adjacent to each other; a plurality of first polysilicon electrodes extending in the horizontal direction, each of said first polysilicon electrodes being formed on a surface of a substrate through an insulating layer and having a base portion being arranged apart from and parallel to each other; a plurality of second polysilicon electrodes extending in the horizontal direction, each of said second polysilicon electrodes being formed on the surface of the substrate through the insulating layer and having a base portion being arranged apart from and parallel to each other; a plurality of third polysilicon electrodes having a base portion extending in the horizontal direction, a plurality of metal wiring films extending in the vertical direction, each of said metal wiring films being arranged in the horizontal direction on all of said polysilicon electrodes covered with the insulating layer, each of said metal wiring films being used as electrodes for applying a clock pulse for vertical transfer of signal charges to all of said polysilicon electrodes; a plurality of first openings being formed through the insulating layer such that each of said metal wiring films contact each of said first polysilicon electrodes; a plurality of second openings being formed through the insulating layer such that each of said metal wiring films contacts each of said second polysilicon electrodes; and a plurality of third openings being formed through the insulating layer such that each of said metal wiring films contacts each of said third polysilicon electrodes, characterized in that said first polysilicon electrodes have a plurality of branched portions projecting perpendicularly from the base portion thereof, said second polysilicon electrodes have a plurality of branched portions projecting perpendicularly from the base portion thereof so as to be opposed to each of the branched portions of each of said first polysilicon electrodes, wherein the base portion of each of said second polysilicon electrodes overlaps that of each of said first polysilicon electrodes through the insulating layer; said third polysilicon electrodes have a plurality of branched portions projecting perpendicularly from opposite sides of their base portion so that each of said third polysilicon electrodes are disposed over each of said first and second polysilicon electrodes through the insulating layer; and wherein every first and second metal wiring film contacts the branched portions of the first and second polysilicon electrodes through said first and second openings (claim 1). Further advantageous developments are specified in the depending claims 2 - 5. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a plan view of the principles of the known charge coupled devices. Figure 2 is a sectional view of the charge coupled device taken along line I-I of Figure 1; Figure 3 is a sectional view of the charge coupled device taken along line II-II of Figure 1; Figure 4 is a sectional view of the charge coupled device taken along line III-III of Figure 1; Figure 5 is a plan view of a charge coupled device according to an embodiment of the present invention; Figure 6 is a plan view of the first polysilicon electrodes used in the charge coupled device of the embodiment; Figure 7 is a plan view of second polysilicon electrodes used in the charge coupled device of the embodiment; Figure 8 is a plan view of a third polysilicon electrode used in the charge coupled device of the embodiment; Referring to Figures 1 to 4, a CCD known in the art (refer e.g. to JP-A-56 087 379) includes first, second and third polysilicon electrodes 10, 11, 12 which are formed on a semiconductor substrate, such as silicon, and extend parallel to each other in the horizontal transfer direction (X-direction). The charge coupled device also includes a plurality of aluminum wiring films 13 which extend in the vertical transfer direction (Y-direction) perpendicular to the horizontal transfer direction. An insulating layer 14 made of silicon oxide is formed on a surface of a substrate 9 and fills spaces between the polysilicon electrodes 10, 11 and 12 and between the polysilicon electrodes 10, 11 and 12 and the aluminum wiring films 13, whereby the respective polysilicon electrodes 10, 11 and 12 and aluminum wiring films 13 are electrically separated from each other. The first polysilicon electrodes 10 are formed on the substrate 9 through the insulating layer 14 and arranged apart from and adjacent to each other. Each of the first polysilicon electrodes 10 has a plurality of rectangular tooth-like branched portions projecting from one side of a base portion thereof in the vertical transfer direction. Each of the second polysilicon electrodes 11 has a plurality of rectangular tooth-like branched portions projecting from one side of a base portion thereof in the vertical transfer direction so as to be opposite the branched portions of the first polysilicon electrode 10. The second polysilicon electrodes 11 are formed on the substrate 9 such that the base portion of the electrode 11 partially extends over the base portion of the electrode 10, where the parts of both electrodes overlap each other through the insulating layer 14. The third polysilicon electrode 12 has rectangular branched portions projecting in the vertical transfer direction from the opposite sides of a base portion thereof and formed on the substrate 9 such that end portions of the branched portions are partially extended over the branched portions of the electrodes 10 and 11 covered with the insulating layer 14. The aluminum wiring films 13 are formed as an uppermost layer and extend over the partially overlapped base portions of the electrodes 10 and 11 and the respective branched portions of the electrodes 10, 11 and 12 so that the vertical transfer lines of the charge coupled device extend along the aluminum wiring films 13. Thus, the aluminum wiring films 13 cover each vertical transfer line to thereby prevent the same from being exposed to incident light. In addition, the aluminum wiring films 13 serve as an electrode for applying clock pulses through the polysilicon electrodes 10, 11 and 12 to the substrate on the vertical transfer line. Upon application of the clock pulses, signal charges generated at a p-n junction photodiode of a picture element is are transmitted via the vertical transfer line. The polysilicon electrodes 10, 11 and 12 are contacted with the overlaid aluminum wiring films 13 through contact portions 13A, 13B and 13C which contact respective electrodes through openings fermed in the insulating layer 14. As shown in Figure 1, the first polysilicon layer 10 is connected to the aluminum wiring films 13 through the contact portions 13A, 13A, while the second and third polysilicon layer 11 and 12 are connected to the aluminum wiring films 13 through the contact portions 13B, 13B and the contact portions 13C, 13C, respectively. Namely, the contact portions 13A, 13A, the contact portions 13B, 13B and the contact portions 13C, 13C are respectively arranged along the vertical transfer lines to thereby form separate vertical rows. Each row of aligned contact portions 13A, 13B and 13C appears under every third aluminum wiring film 13 extending along the vertical lines. As is apparent from the drawing, the contact portions 13A, 13A are formed such that all the underlaid first polysilicon electrodes 10 are allowed to be in contact with the corresponding aluminum wiring film 13. The contact portions 13B, 13B and the contact portions 13C, 13C are provided in the same manner as the contact portions 13A, 13A. One end of the contact portions 13A, 13A is terminated at the branched portion of the first polysilicon electrode 10 where the connection between the aluminum wiring film 13 and the electrode 10 is created. The contact portions 13B, 13B are also formed through the insulating layer 14 so that the branched portions of the second polysilicon electrodes 11 are connected to the aluminum wiring film 13 while the contact portions 13C, 13C serve as connections between the base portion of the third polysilicon electrode 12 and the aluminum wiring films 13. As illustrated in Figures 2 to 4, the third polysilicon electrode 12 is designed such that only a small end area of each branched portion is overlapped with the corresponding end of the branched portion of each of the first and second polysilicon electrodes 10 and 11. To this end, the contact portions 13A, 13B and 13C having large sectional areas can be formed through the insulating film 14 whereby connection between the aluminum wiring films 13 and the first, second and third polysilicon electrodes 10, 11 and 12 is considerably facilitated. A charge coupled device according to an embodiment of the present invention will be described with reference to the accompanying drawing, Figs. 5 to 8 in which like numerals indicate like parts of the CCD of the above described prior art. Figures 5 to 8 depict the charge coupled device according to the embodiment of the invention. Referring to Figure 5, the charge coupled device includes first, second and third polysilicon electrodes 10, 11 and 12 extending in a horizontal transfer direction and a plurality of aluminum wiring films 13 extending in the vertical transfer direction. An insulating layer (not shown) made of silicon oxide is formed on a surface of a substrate (not shown) and fills spaces between the polysilicon electrodes 10, 11 and 12 and the aluminum wiring films 13. The first polysilicon electrodes 10 are formed on the substrate through the insulating layer and arranged apart from and adjacent to each other. As illustrated in Figure 6, each of the first polysilicon electrodes 10 has a plurality of rectangular tooth-like branched portions extending in the vertical transfer direction from the side of a base portion thereof. As illustrated in Figure 7, each of the second polysilicon electrodes 11 has a plurality of rectangular tooth-like branched portions extending from the side of a base portion thereof in the vertical transfer direction so as to be opposite the branched portions of the first polysilicon electrodes 10. The second polysilicon electrodes 11 are formed on the substrate such that the base portion of the electrode 11 partially extends over the base portion of the electrode 10, where the parts of both electrodes overlap each other through the insulating layer. As illustrated in Figures 5 and 8, the third polysilicon electrode 12 has a gate portion 12A which extends in the vertical transfer direction, a base portion 12D extending in the horizontal direction and first and second branched portions 12B and 12C which extend oppositely in the vertical transfer direction from the base portion. The third polysilicon electrode 12 is formed on the surface of the substrate such that the base portion thereof overlaps the overlapping base portions of the first and second polysilicon electrodes 10 and 11 through the insulating layer. The gate portion 12A extends continuously in the vertical transfer direction traversing the respective base and branched portions of the overlapping first and second polysilicon electrodes 10 and 11. The first branched portion 12B extends from the branched portion of the first polysilicon electrode 10 toward the branched portion of the second polysilicon electrode 11. On the other hand, the second projection 12C oppositely extends from the branched portion of the second polysilicon electrode 11 toward the branched portion of the first polysilicon electrode 10. As shown in Figure 5, the aluminum wiring films 13 are disposed along the vertical transfer lines, traversing the base portions of the polysilicon electrodes 10, 11 and 12. Under the respective aluminum wiring films 13, the contact portions 13A, 13B and 13C, which serve for connection between the polysilicon electrodes 10, 11 and 12 and the aluminum wiring films 13, are formed through the insulating layer in the same manner as in the first embodiment of the invention mentioned above. Namely, the contact portions 13A, 13B and 13C are separately arranged in different vertical rows. Each vertically aligned row of the contact portions 13A, 13B and 13C appear under every third aluminum wiring film 13. As a result, every first and second aluminum wiring film 13 contacts the branched portions of the first and second polysilicon electrodes 10 and 11 through the contact portions 13A and 13B. Further, every third aluminum wiring film 13 contacts the gate portion 12A through the contact portion 13C. As is obvious from the aforementioned description of the preferred embodiment according to the present invention, a plurality of polysilicon electrodes contact a plurality of aluminum wiring films through a plurality of openings formed in an insulating layer which fills spaces between the polysilicon electrodes and the aluminum wiring films.

Claims: A non-interlacing charge coupled device of a frame interline transfer (FIT) type comprising: a plurality of picture elements (15) being aligned in the vertical direction, rows of said vertically aligned picture elements being arranged parallel and adjacent to each other; a plurality of first polysilicon electrodes (10) extending in the horizontal direction, each of said first polysilicon electrodes being formed on a surface of a substrate through an insulating layer and having a base portion being arranged apart from and parallel to each other; a plurality of second polysilicon electrodes (11) extending in the horizontal direction, each of said second polysilicon electrodes being formed on the surface of the substrate through the insulating layer and having a base portion being arranged apart from and parallel to each other; a plurality of third polysilicon electrodes (12) having a base portion extending in the horizontal direction; a plurality of metal wiring films (13) extending in the vertical direction, each of said metal wiring films being arranged in the horizontal direction on all of said polysilicon electrodes covered with the insulating layer, each of said metal wiring films being used as electrodes for applying a clock pulse for vertical transfer of signal charges to all of said polysilicon electrodes; a plurality of first openings (13A) being formed through the insulating layer such that each of said metal wiring films contact each of said first polysilicon electrodes (10); a plurality of second openings (13B) being formed through the insulating layer such that each of said metal wiring films contacts each of said second polysilicon electrodes (11); and a plurality of third openings (13C) being formed through the insulating layer such that each of said metal wiring films contacts each of said third polysilicon electrodes (12), characterized in that said first polysilicon electrodes (10) have a plurality of branched portions projecting perpendicularly from the base portion thereof, said second polysilicon electrodes (11) have a plurality of branched portions projecting perpendicularly from the base portion thereof so as to be opposed to each of the branched portions of each of said first polysilicon electrodes (10), wherein the base portion of each of said second polysilicon electrodes (11) overlaps that of each of said first polysilicon electrodes (10) through the insulating layer; said third polysilicon electrodes (12) have a plurality of branched portions (12A, 12B, 12C) projecting perpendicularly from opposite sides of their base portion so that each of said third polysilicon electrodes (12) are disposed over each of said first and second polysilicon electrodes through the insulating layer; and wherein every first and second metal wiring film (13) contacts the branched portions of the first and second polysilicon electrodes through said first and second openings (13A, 13B). The charge coupled device according to claim 1, wherein each of said metal wiring films (13) is used as a photo-shield means for shielding all of said polysilicon electrodes from incident light. The charge coupled device according to claim 1, wherein each said third polysilicon electrode (12) further comprises a gate portion (12A) extending in the vertical direction and every third metal wiring film (13) contacts the gate portion (12A) through the third openings (13C). The charge coupled device according to claim 1, wherein said branched portions of said third polysilicon electrode (12) comprise first branched portions (12B) projecting from one side of the base portions and extending from the branched portion of said first polysilicon electrode (10) towards the branched portion of said second polysilicon electrode (11), and second branched portions (12C) projecting from the other side of the base portions and extending from the branched portion of the said second polysilicon electrode (11) towards the branched portion of polysilicon electrode (10) said first and second branched portions being alternately arranged on the base portion. The charge coupled device of one of the preceding claims, wherein all of said branched portions are provided at regular intervals along said base portions and have a rectangular tooth-like form.

Inventors: FURUKAWA JUNICHI, KANBE HIDEO, FURUKAWA, JUNICHI, KANBE, HIDEO
Applicants: SONY CORP, SONY CORPORATION
Application year: 1991
Main classification: H01L27
IPC codes: H01L27, H04N5