US 6310366

Patent Overview — US 6,310,366 B1

Title: "Retrograde well structure for a CMOS imager"

Patent number / application: US 6,310,366 B1; Application US09/334,261.

Inventors: Howard E. Rhodes and Mark Durcan.

Assignee: Original assignee Micron Technology Inc.; current assignee listed as Aptina Imaging Corp (a reassignment recorded 2009-08-04).

Key dates: Priority/filing date 1999-06-16; publication/grant 2001-10-30; anticipated expiration 2019-06-16. Legal status: expired – lifetime. The source notes that legal status and assignee listings are assumptions, not legal conclusions.

Purpose / plain-language scope: The patent relates generally to improved semiconductor imaging devices, specifically a silicon imaging device fabricable using a standard CMOS process. The description explains that CMOS imagers are attractive for low-cost imaging because they offer low voltage and low power operation, compatibility with on-chip electronics (control logic, timing, image processing, A/D conversion), random access to image data, and lower fabrication cost using standard CMOS processing. A CMOS imager circuit conventionally includes a focal plane array of pixel cells, each with a photogate, photoconductor, or photodiode accumulating photo-generated charge in the underlying substrate, plus readout circuitry including an output field-effect transistor and a charge-transfer section with a sensing (floating diffusion) node. Active pixel functions described include photon-to-charge conversion, charge accumulation, charge transfer with amplification, node reset, pixel selection, and output/amplification. The photosensitive element is typically a depleted p‑n junction photodiode or a field-induced depletion region beneath a photogate; image lag can be eliminated by fully depleting the photodiode upon readout. Prior-art keywords indexed for this patent include "retrograde well," "imager," and concentration units "atoms per," consistent with the title's subject matter.

Source: https://patents.google.com/patent/US6310366/en

What the excerpt does not establish: The supplied text is an excerpt; the detailed description and all claims are omitted. It does not provide the specific retrograde well structure, dopant concentrations, or claim language; nor does it establish the full specification, drawings, or prosecution history.