Method for fabricating a double wall tub shaped capacitor

A method of fabricating a capacitor having a double wall cup shaped storage electrode for a memory device on a substrate;

• said substrate having a device area with a source region formed therein, comprising the steps of:
• a) forming an etch barrier layer over the substrate;
• b) forming a first insulating layer composed of silicon oxide over said device area and elsewhere over said substrate;
• said first insulating layer having a top surface;
• c) forming a first resist layer over the first insulating layer;
• said first resist layer having a first opening over said source region;
• d) isotropically etching an upper portion of said first insulation layer through said first opening forming a cup shaped hole;
• e) anisotropically etching said first insulating layer through said first opening forming a contact hole to partially expose said source;
• f) removing said first resist layer;
• g) forming a conformal first conductive layer composed of polysilicon over the first insulating layer, over said cup shaped hole and in said contact hole thereby forming an electrical contact with said source;
• said first conductive layer having curved sidewalls on the sidewalls of said cup shaped hole;
• h) patterning said first conductive layer to leave a portion of said first conductive layer over said device area;
• the patterning defining a cup shaped electrode having a lower portion and a cup shaped outer wall;
• said cup shaped outer wall having a horizontal fin over said top surface of said first insulating layer;
• i) forming spacers over the curved sidewalls of said first conductive layer;
• said spacers having sidewalls;
• j) forming a vertical cylindrical inner wall on said sidewalls of said spacers and exposing a central bottom portion of said cup shaped outer wall;
• k) completely removing said spacers and said first insulating layer using an etch thereby forming said double wall cup shaped storage electrode;
• and
• l) sequentially forming a capacitor dielectric layer and a top electrode over at least said double wall cup shaped storage electrode thereby forming a double wall cup shaped capacitor.

A method of fabricating a capacitor having a double wall tub shaped storage electrode for a memory device on a substrate;

• said substrate having a device area with a source region formed therein, comprising the steps of:
• a) forming sequentially a first conformal layer, an etch barrier layer composed of silicon nitride, and a first insulating layer composed of silicon oxide over said substrate;
• said first insulating layer having a top surface;
• (1) said first insulating layer is composed of a material selected from a group consisting of:
• borophosphosilicate glass, BPTEOS and silicon oxide;
• and has a thickness in the range of between about 10,000 and 20,000 .ANG.;
• b) patterning said first insulating layer to form a contact hole to partially expose said source region;
• c) removing an upper portion of said first insulating layer centered around said contact hole forming a tub hole centered over said contact hole;
• said tub hole having vertical sidewalls and a horizontal bottom;
• the removal of said upper portion of said first insulation layer comprises:
• forming a first photoresist layer having a first opening over said source region which defines the area for the formation of said double wall tub shaped storage electrode;
• and anisotropically etching said first insulating layer through said first opening removing an upper portion of said first insulating layer;
• d) forming a first conductive layer composed of polysilicon over said first insulating layer, in said tub hole and in said contact hole thereby forming an electrical contact with said source;
• said first conductive layer having vertical sidewalls on the vertical sidewalls of said tub hole;
• e) forming spacers over said vertical sidewalls of said first conductive layer;
• said spacers having vertical sidewalls;
• (1) said spacers are formed of a material selected from a group consisting of silicon oxide, borophosphosilicate glass and BPTEOS;
• and have a thickness in the range of between about 1000 and 3000 .ANG.;
• f) patterning said first conductive layer forming a storage electrode aligned to said device area, said storage electrode having a horizontal fin on said top surface of said first insulating layer, said horizontal fin having outer vertical sidewalls;
• the patterning of said first conductive layer comprises:
• forming a second photoresist layer over said first conductive layer;
• said second photoresist layer covering said device areas and having a second opening;
• and etching said first conductive layer through said second opening thereby defining said storage electrode;
• g) forming a vertical inner wall of polysilicon on said vertical sidewalls of said spacers exposing a central bottom portion of said storage electrode and forming outer spacers of polysilicon on said outer vertical sidewalls of said horizontal fin;
• the vertical inner;
• (1) said vertical inner wall is created by forming a second conductive layer over said first insulating layer and said storage electrode and anisotropically etching said second conductive layer;
• said vertical inner wall has a thickness in a range of between about 500 and 2500 .ANG.;
• h) completely removing said spacers and said first insulating layer thereby forming said double wall tub shaped storage electrode;
• said etch barrier layer protects said first conformal layer;
• and
• i) sequentially forming a capacitor dielectric layer and a top electrode over at least said double wall tub shaped storage electrode thereby forming said capacitor.

A method of fabricating a capacitor having a double wall cup shaped storage electrode for a memory device on a substrate;

• said substrate having a device area with a source region formed therein, comprising the steps of:
• a) sequentially forming a first conformal layer, and an etch barrier layer over the substrate;
• (1) said first conformal layer is composed of silicon oxide and has a thickness in a range of between about 500 and 3000 .ANG. and said etch barrier layer is composed of silicon nitride and has a thickness in a range of between about 500 and 3000 .ANG.;
• b) forming a first insulating layer over said device area and elsewhere over said substrate;
• said first insulating layer having a top surface;
• (1) said first insulating layer is composed of a material selected from the group consisting of:
• BPSG, BPTEOS, and silicon oxide;
• and has a thickness in the range of between about 10,000 and 20,000 .ANG.;
• c) forming a first resist layer over the first insulating layer;
• said first resist layer having a first opening over said source region;
• d) isotropically etching an upper portion of said first insulation layer through said first opening forming a cup shaped hole;
• e) anisotropically etching said first insulating layer through said first opening forming a contact hole to partially expose said source;
• f) removing said first resist layer;
• g) forming a conformal first conductive layer composed of polysilicon over the first insulating layer, over said cup shaped hole and in said contact hole thereby forming an electrical contact with said source;
• said first conductive layer having curved sidewalls on the sidewalls of said cup shaped hole;
• h) patterning said first conductive layer to leave a portion of said first conductive layer over said device area;
• the patterning defining a cup shaped electrode a lower portion and a cup shaped outer wall;
• said cup shaped outer wall having a horizontal fin over said top surface of said first insulating layer;
• i) forming spacers over the curved sidewalls of said first conductive layer;
• said spacers having sidewalls;
• j) forming a vertical cylindrical inner wall of polysilicon on said sidewalls of said spacers and exposing a central bottom portion of said cup shaped outer wall;
• k) completely removing said spacers and said first insulating layer using an etch thereby forming said double wall cup shaped storage electrode;
• and
• l) sequentially forming a capacitor dielectric layer and a top electrode over at least said double wall cup shaped storage electrode thereby forming a double wall cup shaped capacitor.