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High density dynamic random access memory cell structure having a polysilicon pillar capacitor

  • US 5,595,928 A
  • Filed: 09/18/1995
  • Issued: 01/21/1997
  • Est. Priority Date: 09/18/1995
  • Status: Expired due to Term
First Claim
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1. A method for fabricating stacked storage capacitors on a semiconductor substrate, comprising the steps of:

  • providing a semiconductor substrate having field oxide areas surrounded and electrically isolated device areas, said device areas having semiconductor devices formed, in part, from a patterned first polysilicon layer, and said devices areas having device contact areas;

    depositing a first insulating layer on said substrate and over said patterned first polysilicon layer,depositing a second insulating layer on said first insulating layer;

    anisotropically etching node contact openings in said second and first insulating layers to said device contact areas, thereby forming node contact openings having essentially vertical sidewalls for stacked storage capacitor bottom electrodes;

    depositing a conformal second polysilicon layer, and thereby filling said node contact openings, and also forming a uniformly thick second polysilicon layer elsewhere on said second insulating layer;

    oxidizing by thermal oxidation said second poly-silicon layer to said second insulating layer, and thereby leaving unoxidized polysilicon pillars in said node contact openings having essentially vertical sidewalls;

    isotropically etching said oxidized portion of said second polysilicon layer, and by said same isotropic etch, etching selectively said second insulating layer to said first insulating layer leaving free standing polysilicon pillars and thereby forming pillar-shaped bottom electrodes;

    forming a capacitor interelectrode dielectric layer on said bottom electrodes, anddepositing and patterning a third polysilicon layer, and completing said stacked storage capacitors.

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