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Image sensor including dual isolation and method of making the same

  • US 10,192,918 B2
  • Filed: 10/19/2015
  • Issued: 01/29/2019
  • Est. Priority Date: 04/03/2009
  • Status: Active Grant
First Claim
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1. A method comprising:

  • providing a mask over a substrate, wherein the substrate has a pixel area and a periphery area;

    patterning a first opening in the pixel area and a second opening in the periphery area;

    etching the mask via the first opening and the second opening;

    protecting an entirety of the periphery area;

    etching the substrate via the first opening to form a first STI structure having a first depth;

    protecting the pixel area;

    etching the substrate via the second opening to form a second STI structure having a second depth deeper than the first depth;

    depositing an oxide layer in the first and the second STI structures;

    removing the mask and an entirety of the oxide layer located above a top surface of the substrate, wherein after removal a surface of the oxide layer is coplanar with the top surface of the substrate;

    forming at least one photo detector comprising one or more first NMOS devices in the pixel area, with the proviso that the pixel area does not contain any PMOS devices; and

    forming second NMOS devices and PMOS devices in the periphery area.

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