Method of manufacturing a DRAM cell having a double-crown capacitor using polysilicon and nitride spacers

A method for fabricating an array of dynamic random access memory cells having double-crown storage capacitors on a semiconductor substrate, comprising the steps of:

• providing a semiconductor substrate having device areas surrounded and electrically isolated from each other by field oxide areas;
• depositing a first polycide layer on said device areas and elsewhere on said substrate;
• depositing a first insulating layer on said first polycide layer;
• patterning said first insulating layer on said first polycide layer and forming gate electrodes for field effect transistors on said device areas and word lines on said field oxide areas;
• ion implanting and thereby forming lightly doped drain areas adjacent to said gate electrodes in said device areas;
• depositing a conformal second insulating layer and anisotropically etching back to form sidewall spacers on said gate electrodes;
• ion implanting and thereby forming source/drain areas for said field effect transistors;
• depositing a third insulating layer having a planar surface;
• depositing a first polysilicon layer on said third insulating layer;
• patterning said first polysilicon layer by anisotropic plasma etching and partially etching into said third insulating layer over said device areas adjacent to said gate electrodes forming first recessed areas;
• depositing a conformal second polysilicon layer and anisotropically etching back thereby forming polysilicon spacers on the sidewalls of said first recessed areas;
• anisotropically etching said third insulating layer in said first recessed areas thereby forming concurrently bit line contact openings and capacitor node contact openings;
• depositing a third polysilicon layer thereby filling said contact openings;
• depositing a silicide layer on said third polysilicon layer;
• depositing a silicon nitride layer on said silicide layer;
• patterning said silicon nitride layer, said silicide layer, and said third polysilicon layer thereby forming bit lines and concurrently forming node contacts for said capacitors;
• depositing a conformal second silicon nitride layer and anisotropically etching back to form silicon nitride spacers on said bit lines;
• depositing a fourth polysilicon layer on said substrate;
• depositing a fourth insulating layer on said fourth polysilicon layer and planarizing said fourth insulating layer;
• patterning said fourth insulating layer by photoresist masking and anisotropically etching partially into said fourth insulating layer leaving unetched portions over said node contacts forming second recessed areas elsewhere on said substrate;
• depositing a conformal fifth polysilicon layer and anisotropically etching back to form polysilicon spacers on the sidewalls of said second recessed areas;
• anisotropically etching said fourth insulating layer to said fourth polysilicon layer using said polysilicon spacers as an etch mask thereby forming narrow vertical insulating regions under said polysilicon spacers;
• removing said polysilicon spacers and also removing said fourth polysilicon layer to said first silicon nitride layer;
• depositing a conformal sixth polysilicon layer;
• anisotropically blanket etching said sixth polysilicon layer thereby forming polysilicon double-crown sidewall spacers on said narrow vertical insulating regions;
• selectively etching said narrow vertical insulating regions thereby forming an array of bottom electrodes for said double-crown capacitors;
• depositing a thin interelectrode dielectric layer on said bottom electrodes;
• depositing a conducting layer on said dielectric layer thereby completing said array of dynamic random access memory cells having said double-crown capacitors.