SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME

• US 20100019312A1
• Filed: 07/28/2009
• Published: 01/28/2010
• Est. Priority Date: 07/28/2008
• Status: Active Grant

• Current Assignee: Kioxia Corporation
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Sekihara, Akiko, Ozawa, Yoshio, SEKINE, Katsuyuki, Takano, Kensuke
• Granted Patent: US 8,253,189 B2
• Time in Patent Office: Days
• US Class Current: 257/326
• CPC Class Codes: H01L 29/513 the variation being perpendicular to the channel plane
• CPC Class Codes: H01L 29/66833 with a charge trapping gate insulator, e.g. MNOS transistors
• CPC Class Codes: H01L 29/792 with charge trapping gate insulator, e.g. MNOS-memory transistors
• CPC Class Codes: H01L 29/7926 Vertical transistors, i.e. transistors having source and drain not in the same horizontal plane
• CPC Class Codes: H10B 43/10 characterised by the top-view layout
• CPC Class Codes: H10B 43/20 characterised by three-dimensional arrangements, e.g. with cells on different height levels
• CPC Class Codes: H10B 43/27 the channels comprising vertical portions, e.g. U-shaped channels

Abstract

A semiconductor device includes a semiconductor region, a tunnel insulating film formed on a surface of the semiconductor region, a charge-storage insulating film formed on a surface of the tunnel insulating film and containing silicon and nitrogen, a block insulating film formed on a surface of the charge-storage insulating film, and a control gate electrode formed on a surface of the block insulating film, wherein the tunnel insulating film has a first insulating film formed on the surface of the semiconductor region and containing silicon and oxygen, a second insulating film formed on a surface of the first insulating film, and a third insulating film formed on a surface of the second insulating film and containing silicon and oxygen, and a charge trap state in the second insulating film has a lower density than that in the charge-storage insulating film.

Claims

1. A semiconductor device comprising:

a semiconductor region;

a tunnel insulating film formed on a surface of the semiconductor region;

a charge-storage insulating film formed on a surface of the tunnel insulating film and containing silicon and nitrogen;

a block insulating film formed on a surface of the charge-storage insulating film; and

a control gate electrode formed on a surface of the block insulating film,

wherein the tunnel insulating film has a first insulating film formed on the surface of the semiconductor region and containing silicon and oxygen, a second insulating film formed on a surface of the first insulating film, and a third insulating film formed on a surface of the second insulating film and containing silicon and oxygen, and

a charge trap state in the second insulating film has a lower density than that in the charge-storage insulating film.

2. The device according to claim 1, wherein the second insulating film contains silicon, nitrogen, and oxygen, and has a higher oxygen concentration than the charge-storage insulating film.

3. The device according to claim 2, wherein the oxygen in the second insulating film has a higher average concentration than that in the charge-storage insulating film.

4. The device according to claim 2, wherein the oxygen in a central portion of the second insulating film has a higher concentration than the oxygen in a vicinity of an interface between the first insulating film and the second insulating film and the oxygen in a vicinity of an interface between the second insulating film and the third insulating film.

5. The device according to claim 2, wherein the oxygen in a central portion of the second insulating film has a lower concentration than the oxygen in a vicinity of an interface between the first insulating film and the second insulating film and the oxygen in a vicinity of an interface between the second insulating film and the third insulating film.

6. The device according to claim 1, wherein the second insulating film contains silicon, nitrogen, and a predetermined element selected from hydrogen, deuterium, and halogen, and the predetermined element in the second insulating film has a higher concentration than that in the charge-storage insulating film.

7. The device according to claim 6, wherein the predetermined element in the second insulating film has a higher average concentration than that in the charge-storage insulating film.

8. The device according to claim 6, wherein the predetermined element in a central portion of the second insulating film has a higher concentration than the predetermined element in a vicinity of an interface between the first insulating film and the second insulating film and the predetermined element in a vicinity of an interface between the second insulating film and the third insulating film.

9. The device according to claim 6, wherein the predetermined element in a central portion of the second insulating film has a lower concentration than the predetermined element in a vicinity of an interface between the first insulating film and the second insulating film and the predetermined element in a vicinity of an interface between the second insulating film and the third insulating film.

10. The device according to claim 1, wherein the second insulating film contains silicon and nitrogen, and has a lower silicon composition ratio than the charge-storage insulating film.

11. The device according to claim 10, wherein the second insulating film has a higher nitrogen composition ratio than the charge-storage insulating film.

12. A method for manufacturing a semiconductor device a tunnel insulating film formed on a surface of a semiconductor region, a charge-storage insulating film formed on a surface of the tunnel insulating film and containing silicon and nitrogen, a block insulating film formed on a surface of the charge-storage insulating film, and a control gate electrode formed on a surface of the block insulating film,

wherein a process of manufacturing the tunnel insulating film comprises:

forming a first insulating film containing silicon and oxygen on the surface of the semiconductor region;

introducing nitrogen into an upper portion of the first insulating film to form a second insulating film containing silicon, nitrogen, and oxygen; and

forming a third insulating film containing silicon and oxygen on a surface of the second insulating film.

13. The method according to claim 12, wherein nitrogen is introduced into the upper portion of the first insulating film using plasma or radicals.

14. The method according to claim 12, wherein the second insulating film has a higher oxygen concentration than the charge-storage insulating film.

15. A method for manufacturing a semiconductor device comprising a tunnel insulating film formed on a surface of a semiconductor region, a charge-storage insulating film formed on a surface of the tunnel insulating film and containing silicon and nitrogen, a block insulating film formed on a surface of the charge-storage insulating film, and a control gate electrode formed on a surface of the block insulating film,

the tunnel insulating film including a first insulating film formed on a surface of the semiconductor region and containing silicon and oxygen, a second insulating film formed on a surface of the first insulating film and containing silicon and nitrogen, and a third insulating film formed on a surface of the second insulating film and containing silicon and oxygen,

wherein forming the second insulating film, the second insulating film is formed at a lower temperature than the charge-storage insulating film.

16. The method according to claim 15, wherein the second insulating film has a lower silicon composition ratio than the charge-storage insulating film.

17. A method for manufacturing a semiconductor device comprising a tunnel insulating film formed on a surface of a semiconductor region, a charge-storage insulating film formed on a surface of the tunnel insulating film and containing silicon and nitrogen, a block insulating film formed on a surface of the charge-storage insulating film, and a control gate electrode formed on a surface of the block insulating film,

wherein a process of forming the tunnel insulating film comprises forming a third insulating film containing silicon and oxygen on an exposed surface of the charge-storage insulating film, introducing nitrogen into an exposed surface side region of the third insulating film to form a second insulating film containing silicon, nitrogen, and oxygen, and forming a first insulating film containing silicon and oxygen on an exposed surface of the second insulating film.

18. The method according to claim 17, wherein nitrogen is introduced into the upper portion of the first insulating film using plasma or radicals.

19. The method according to claim 17, wherein the second insulating film has a higher oxygen concentration than the charge-storage insulating film.