US 4,228,445 AGranted

Dual plane well-type two-phase ccd

AssigneeTexas Instruments Incorporated

InventorsAl F. Tasch, Jr., Pallab K. Chatterjee

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Abstract

A charge coupled device having geometries suitable for fabrication in high density packages (64,000 bits per chip-1,000,000 bits per chip) is comprised of a semiconductor substrate having dopant impurity atoms of a first type and a first surface. A charge transfer channel lies in the substrate near the first surface, and it is overlaid by an insulating layer of non-uniform thickness. A plurality of first and second electrodes lie on the insulating layer traversely to the channel. A well region of dopant impurity atoms of a second type opposite to the first type lies under each of the electrodes. The non-uniform insulating layer underlies each of the first electrodes by a first uniform thickness, underlies the second electrodes by a second uniform thickness, and separates the each of the first and second electrodes by approximately the second thickness. The second thickness is 20%-60% greater than the first thickness to greatly reduce inter-electrode shorts in high density packages. A shallow layer of dopant impurity atoms of the second type may be provided under the second electrodes to compensate for shift flatband voltage shifts due to the thick insulating layer.

Claims8

Dependent claims

A charge-coupled device comprised of:

(a) a semiconductor substrate having dopant impurity atoms of a first type and a first surface;
(b) a charge-transfer channel in said substrate near said first surface;
(c) an insulating layer of non-uniform thickness on said first surface over said channel;
(d) a plurality of first electrodes spaced apart from each other and lying on said insulating layer transversely to said channel;
(e) a plurality of second electrodes lying on said insulating layer transversely to said channel in the spaces between said first electrodes;
(f) a well region of dopant impurity atoms of a second type opposite to said first type under each of said first and second electrodes;
each of said well regions extending transversely across said channel and along said channel from one transverse edge of a respective one of said electrodes to a medial portion of said electrode;
wherein said insulating layer underlies each of said first electrodes by a first uniform thickness, underlies each of said second electrodes by a second uniform thickness, and separates each of said first electrodes from adjacent second electrodes by approximately said second thickness, with said second thickness being approximately 20% to 60% greater than said first thickness.

5 more elements

Dependencies are inferred from the claim text.