US 4481522

Patent Overview — US 4,481,522 A

Title: CCD Imagers with substrates having drift field

Assignee/Applicant: RCA Corp (original assignee; recorded assignment to RCA Corporation, a Corp. of DE)

Inventors: Lubomir L. Jastrzebski and Peter A. Levine

Dates: Priority/filing date 1982-03-24; publication/grant 1984-11-06; anticipated expiration 2002-03-24; status listed as "Expired – Lifetime."

Purpose: The invention concerns charge-coupled device (CCD) imagers with drift fields in their semiconductive substrates to improve CCD operation. It addresses background "striation" patterns in the detected television image, attributed in the text largely to non-uniformity in the density of bulk charge recombination centers, and also cross-talk/cross-color in color-filtered imagers. The stated approach is to create a field—such as a drift field—in the substrate to sweep minority carriers generated in the bulk further into the bulk, away from the electrode-bearing surface, so they recombine with majority carriers instead of reaching depletion regions under gate electrodes. A drift field is said to be generatable by grading impurity doping concentration so it decreases with increasing distance from the surface adjoining the CCD shift-register charge transfer channels.

Plain-language scope (from the excerpt): A CCD imager whose semiconductor substrate includes a doping gradient producing a drift field that drives bulk-generated minority carriers away from the surface where charge transfer channels and gate electrodes reside, reducing striations and cross-talk. The disclosure notes applicability to surface-channel imagers (especially anti-blooming mode) and to suppressing cross-talk in buried-channel imagers; clocking scheme is described as incidental. Figures include a profile/doping-concentration plot (FIGS. 1a–1b), a recombination-probability graph (FIG. 2), color camera block diagrams, and a plan view of a representative CCD imager.

Source: https://patents.google.com/patent/US4481522/en

Not established by this excerpt: The full claim language and exact claimed scope; the complete detailed description and omitted text; the precise fabrication methods or process parameters; and the listed classification scope/definitions beyond those shown.