Semiconductor device and method of manufacturing the same

Abstract

A semiconductor device manufacturing method includes forming a first insulating film on a semiconductor substrate containing silicon, the first insulating film having a first dielectric constant and constituting a part of a tunnel insulating film, forming a floating gate electrode film on the first insulating film, the floating gate electrode film being formed of a semiconductor film containing silicon, patterning the floating gate electrode film, the first insulating film, and the semiconductor substrate to form a first structure having a first side surface, exposing the first structure to an atmosphere containing an oxidizing agent, oxidizing that part of the floating gate electrode film which corresponds to a boundary between the first insulating film and the floating gate electrode film using the oxidizing agent, to form a second insulating film having a second dielectric constant smaller than the first dielectric constant and constituting a part of the tunnel insulating film.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a plan view schematically showing the configuration of a semiconductor device in accordance with a first and second embodiments of the present invention;

FIG. 2 is a diagram showing an equivalent circuit of the semiconductor device in accordance with the first and second embodiments of the present invention;

FIGS. 3A and 3B are sectional views schematically showing part of a method of manufacturing a semiconductor device in accordance with the first embodiment of the present invention;

FIGS. 4A and 4B are sectional views schematically showing part of a method of manufacturing a semiconductor device in accordance with the first embodiment of the present invention;

FIGS. 5A and 5B are sectional views schematically showing part of a method of manufacturing a semiconductor device in accordance with the first embodiment of the present invention;

FIGS. 6A and 6B are sectional views schematically showing part of a method of manufacturing a semiconductor device in accordance with the first embodiment of the present invention;

FIGS. 7A and 7B are sectional views schematically showing part of a method of manufacturing a semiconductor device in accordance with the first embodiment of the present invention;

FIG. 8 is an energy band diagram illustrating a memory cell operation in accordance with the first and second embodiments;

FIG. 9 is an energy band diagram illustrating a memory cell operation in accordance with the first and second embodiments;

FIG. 10 is an energy band diagram illustrating a memory cell operation in accordance with the first and second embodiments;

FIG. 11 is an energy band diagram illustrating a memory cell operation in accordance with the first and second embodiments;

FIG. 12 is a sectional view schematically showing the configuration of a semiconductor device in accordance with the second embodiments of the present invention;

FIG. 13 is a sectional view schematically showing the configuration of a semiconductor device in accordance with a variation of the second embodiment of the present invention;

FIG. 14 is a diagram showing a memory card comprising a NAND type flash memory; and

FIG. 15 is a diagram showing a memory card comprising a NAND type flash memory; and

FIG. 16 is a diagram showing a memory card comprising a NAND type flash memory.

Claims

1. A method of manufacturing a semiconductor device, comprising: forming a first insulating film on a semiconductor substrate containing silicon, the first insulating film having a first dielectric constant and constituting a part of a tunnel insulating film;forming a floating gate electrode film on the first insulating film, the floating gate electrode film being formed of a semiconductor film containing silicon;patterning the floating gate electrode film, the first insulating film, and the semiconductor substrate to form a first structure having a first side surface;exposing the first structure to an atmosphere containing an oxidizing agent;oxidizing that part of the floating gate electrode film which corresponds to a boundary between the first insulating film and the floating gate electrode film using the oxidizing agent, to form a second insulating film having a second dielectric constant smaller than the first dielectric constant and constituting a part of the tunnel insulating film;forming an inter electrode insulating film on the first structure;forming a control gate electrode film on the inter electrode insulating film; andpatterning the control gate electrode film, the inter electrode insulating film, and the floating gate electrode film to form a second structure having a second side surface perpendicular to the first side surface.

2. The method according to claim 1, wherein forming the second insulating film includes oxidizing that part of the semiconductor substrate which corresponds to a boundary between the first insulating film and the semiconductor substrate using the oxidizing agent, to form a third insulating film having a third dielectric constant smaller than the first dielectric constant and constituting a part of the tunnel insulating film.

3. The method according to claim 1, wherein the oxidizing agent contains oxygen and nitrogen, and the second insulating film is formed of an oxide film containing nitrogen.

4. The method according to claim 1, wherein the first insulating film is formed of a nitride film obtained by nitriding a surface of the semiconductor substrate.

5. The method according to claim 1, wherein the first insulating film is formed of a silicon nitride film.

6. The method according to claim 1, wherein the first insulating film is formed of a metal oxide film.

7. The method according to claim 1, wherein the second insulating film is formed of a silicon oxide film or a silicon oxide film containing nitrogen.

8. The method according to claim 1, wherein the second insulating film is thicker at its ends than in its center in a direction perpendicular to the first side surface.

9. A method of manufacturing a semiconductor device, comprising: forming a first insulating film on a semiconductor substrate containing silicon, the first insulating film having a first dielectric constant and constituting a part of a tunnel insulating film;forming a floating gate electrode film on the first insulating film, the floating gate electrode film being formed of a semiconductor film containing silicon;patterning the floating gate electrode film, the first insulating film, and the semiconductor substrate to form a first structure having a first side surface;forming an inter electrode insulating film on the first structure;forming a control gate electrode film on the inter electrode insulating film;patterning the control gate electrode film, the inter electrode insulating film, the floating gate electrode film to form a second structure having a second side surface perpendicular to the first side surface;exposing the second structure to an atmosphere containing an oxidizing agent; andoxidizing that part of the floating gate electrode film which corresponds to a boundary between the first insulating film and the floating gate electrode film using the oxidizing agent, to form a second insulating film having a second dielectric constant smaller than the first dielectric constant and constituting a part of the tunnel insulating film.

10. The method according to claim 9, wherein forming the second insulating film includes oxidizing that part of the semiconductor substrate which corresponds to a boundary between the first insulating film and the semiconductor substrate using the oxidizing agent, to form a third insulating film having a third dielectric constant smaller than the first dielectric constant and constituting a part of the tunnel insulating film.

11. The method according to claim 9, wherein the oxidizing agent contains oxygen and nitrogen, and the second insulating film is formed of an oxide film containing nitrogen.

12. The method according to claim 9, wherein the first insulating film is formed of a nitride film obtained by nitriding a surface of the semiconductor substrate.

13. The method according to claim 9, wherein the first insulating film is formed of a silicon nitride film.

14. The method according to claim 9, wherein the first insulating film is formed of a metal oxide film.

15. The method according to claim 9, wherein the second insulating film is formed of a silicon oxide film or a silicon oxide film containing nitrogen.

16. The method according to claim 9, wherein the second insulating film is thicker at its ends than in its center in a direction perpendicular to the second side surface.

17. A semiconductor device comprising: a semiconductor substrate containing silicon;a tunnel insulating film formed on the semiconductor substrate and including a first insulating film having a first dielectric constant and a second insulating film formed on the first insulating film and having a second dielectric constant smaller than the first dielectric constant;a floating gate electrode formed on the tunnel insulating film and formed of a semiconductor film containing silicon;an inter electrode insulating film formed on the floating gate electrode; anda control gate electrode formed on the inter electrode insulating film,wherein the second insulating film is formed of an oxide film and is thicker at its ends than in its center in a predetermined direction.

18. The device according to claim 17, wherein the tunnel insulating film further includes a third insulating film formed between the semiconductor substrate and the first insulating film and having a third dielectric constant smaller than the first dielectric constant, and the third insulating film is formed of an oxide film and is thicker at its ends than in its center in the predetermined direction.

19. The device according to claim 17, wherein the second insulating film is thicker at its ends than in its center in a direction perpendicular to the predetermined direction.

20. The device according to claim 17, wherein the second insulating film is formed of an oxide film containing nitrogen.