Process for fabricating a stacked capacitor

Claim 1

A method for fabricating a high capacitance stacked storage capacitor over a semiconductor substrate having device areas and word lines formed therein comprising the steps of: depositing a first insulating layer on said device areas, word lines and elsewhere on said substrate; depositing a second insulating layer on said first insulating layer being of different composition from said first insulating layer; forming an opening in said first and second insulating layers for said storage capacitor node contact over and to said device area; depositing a first polysilicon layer over said second insulating layer and over and in said opening in said first and second insulating layer; depositing on said first polysilicon layer a multilayer of two insulator types having alternate layers composed of one insulator type and the other layers composed of the second insulator type; patterning said multilayer having portions over said storage capacitor area and removing portions elsewhere on said first polysilicon layer and said substrate, said multilayer portions having vertical sidewalls; selectively etching one insulator type and leaving said other insulator type unetched in said sidewall of said multilayer and forming a multiple of fin-shaped recesses in said sidewall; depositing a second polysilicon layer over and in said multilayer patterns and in said sidewall recesses forming fin-shaped polysilicon structures and making electrical contact for said storage capacitor to said device area; anisotropically etching back said second and first polysilicon layer and exposing top portions of said multilayer patterns over said storage capacitor area and leaving portions of said second polysilicon on sidewall and in recesses of said multilayer structure and forming a polysilicon multiple fin structure; etching completely and isotropically said multilayer structure and leaving free standing said polysilicon multiple fin structure and thereby forming the bottom electrode of said storage capacitor; depositing a dielectric layer over said bottom electrode and forming an inter-electrode insulating layer; depositing a third polysilicon layer over said dielectric layer forming the top capacitor electrode and completing said stacked storage capacitor having a fin-shaped structure.

Claim 2

A method for fabricating a high capacitance stacked storage capacitor over a semiconductor substrate having device areas and word lines formed therein comprising the steps of: depositing a first insulating layer on said device areas, word lines and elsewhere on said substrate; depositing a second insulating layer on said first insulating layer being of different composition from said first insulating layer; forming an opening in said first and second insulating layers for said storage capacitor node contact over and to said device area; depositing a first polysilicon layer over said second insulating layer and over and in said opening in said first and second insulating layer; depositing on said first polysilicon layer a multilayer of two insulator types having alternate layers composed of one insulator type and the other layers composed of the second insulator type; patterning said multilayer having portions over said storage capacitor area and removing portions elsewhere on said first polysilicon layer and said substrate, said multilayer portions having vertical sidewalls; selectively etching one insulator type and leaving said other insulator type unetched in said sidewall of said multilayer and forming a multiple of fin-shaped recesses in said sidewall; depositing a second polysilicon layer over and in said multilayer patterns and in said sidewall recesses forming fin-shaped polysilicon structures and making electrical contact for said storage capacitor to said device area; anisotropically etching back said second and first polysilicon layer and exposing top portions of said multilayer patterns over said storage capacitor area and leaving portions of said second polysilicon on sidewall and in recesses of said multilayer structure and forming a polysilicon multiple fin structure; etching completely and isotropically said multilayer structure and leaving free standing said polysilicon multiple fin structure and thereby forming the bottom electrode of said storage capacitor; depositing a dielectric layer over said bottom electrode and forming an inter-electrode insulating layer; depositing a third polysilicon layer over said dielectric layer forming the top capacitor electrode and completing said stacked storage capacitor having a fin-shaped structure.