{
  "patent_number": "US 3792322",
  "country": "US",
  "title": "How Buried Channel CCDs Move Data Deep Inside Silicon Chips",
  "original_title": "Buried channel charge coupled devices",
  "summary": "A foundational 1974 invention that improved how computer chips store and move electrical charges by keeping them away from messy surface defects.",
  "what_it_does": "This patent describes a way to move electrical charges through the middle of a semiconductor material rather than along its surface. By creating a 'buried channel'—a specific potential energy path deep inside the silicon—the device prevents charges from getting trapped by surface defects, which were a major problem in early chip designs. The device uses a series of electrode plates on the surface to pull these charges along this internal path, essentially acting like a bucket brigade for electrons. This allows for much faster and more reliable movement of data within the chip.",
  "what_it_does_not_cover": [
    "Does not cover charge-coupled devices that store or transfer charge directly on the semiconductor surface.",
    "Does not cover memory structures that rely on traditional floating-gate transistors for long-term storage.",
    "Does not cover devices lacking the specific ohmic contact means required to bias the storage medium for internal depletion."
  ],
  "filed": "1973-04-19",
  "granted": "1974-02-12",
  "expires": "1993-04-19",
  "status": "expired",
  "holder": "Individual",
  "holder_url": "https://patentbrief.org/company/individual",
  "inventors": [
    {
      "name": "W Boyle",
      "url": "https://patentbrief.org/inventor/w-boyle"
    },
    {
      "name": "G Smith",
      "url": "https://patentbrief.org/inventor/g-smith"
    }
  ],
  "times_cited": 22,
  "tags": [
    "semiconductors",
    "consumer_electronics"
  ],
  "abstract": "The specification describes charge coupled devices in which the storage layer is internally charged so that the energy level profile across the thickness of the layer has a maxima in the middle of the layer. Injected carriers can then be stored and transferred in the bulk region of the semiconductor. If the energy level of the maxima exceeds the surface energy of the valence band by an amount exceeding the Boltzmann expression for thermal excitation, then the stored carriers remain isolated (statistically) from the surface states. The storage layer can be appropriately charged by biasing the layer to remove the mobile carriers. Residual fixed charge bends the energy band if the boundaries are fixed to appropriate barriers. The most convenient structure appears to be a large area p-n junction for the lower (buried) barrier with the usual MIS surface barrier. An MISIM structure is predictably similar. Multichannel structures are proposed such as N-P-N-P-N in which the isolated P-channels serve simultaneously as storage layers. Simultaneous use of both channels with controlled interconnection suggests many potential applications for logic circuits and the availability of convenient crossovers.",
  "url": "https://patentbrief.org/patent/us/3792322/ccd-image-sensor",
  "markdown_url": "https://patentbrief.org/patent/us/3792322/ccd-image-sensor/md",
  "google_patents_url": "https://patents.google.com/patent/US3792322",
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}