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Method for manufacturing DRAM capacitor

  • US 5,998,260 A
  • Filed: 04/06/1998
  • Issued: 12/07/1999
  • Est. Priority Date: 01/14/1998
  • Status: Expired due to Fees
First Claim
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1. A method for manufacturing a DRAM capacitor comprising:

  • providing a substrate having a field effect transistor formed thereon, wherein the field effect transistor includes a source/drain region;

    forming a first dielectric layer and then a second dielectric layer over the substrate;

    patterning the second dielectric layer to form a first opening to expose the first dielectric layer;

    forming a sacrificial layer over the patterned second dielectric layer and filling the first opening, wherein the sacrificial layer is composed of a plurality of alternately stacked first insulating layers and second insulating layers;

    patterning the sacrificial layer to form a second opening exposing the first opening and a portion of the second dielectric layer enclosing the first opening, and then etching the first dielectric layer through the first opening to form a contact opening exposing the source/drain region;

    performing an etching operation whose etching rate on the first insulating layers and the second insulating layers is different, so that a plurality of sunken regions are formed by etching a portion of one of the first and the second insulating layers of the sacrificial layer from a vertical sidewall of the second opening, and the sunken regions form a gear-teeth cavity;

    forming a first conductive layer on a sidewall of the second opening, wherein the first conductive layer also fills the gear-teeth cavity of the sacrificial layer as well as the contact opening such that the first conductive layer is electrically coupled to the exposed source/drain region;

    removing the sacrificial layer to expose the first conductive layer;

    forming a dielectric film over an exposed surface of the first conductive layer; and

    forming a second conductive layer over the dielectric film to serve as a cell electrode.

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