SEMICONDUCTOR STORAGE DEVICE AND MANUFACTURING METHOD THEREOF

• US 20130015541A1
• Filed: 03/20/2012
• Published: 01/17/2013
• Est. Priority Date: 07/11/2011
• Status: Active Grant

• Current Assignee: Kioxia Corporation
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: KANAYA, Hiroyuki
• Granted Patent: US 8,969,983 B2
• Time in Patent Office: Days
• US Class Current: 257/421
• CPC Class Codes: H10B 61/20 comprising components having three or more electrodes, e.g. transistors
• CPC Class Codes: H10B 61/22 of the field-effect transistor [FET] type
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

A memory includes a semiconductor substrate. Cell transistors are on the substrate. Contact plugs each of which is buried between the adjacent cell transistors and electrically connected to a diffusion layer between the adjacent cell transistors. An interlayer dielectric film buries gaps between the contact plugs. A storage element is provided not above the contact plugs but above the interlayer dielectric film. A sidewall film covers a part of a side surface of the storage element, and is provided to overlap with one of the contact plugs as viewed from above a surface of the semiconductor substrate. A lower electrode is provided between a bottom of the storage element and the interlayer dielectric film and between the sidewall film and one of the contact plugs, and electrically connects the storage element to one of the contact plugs.

Claims

1. A semiconductor storage device comprising:

a semiconductor substrate;

a plurality of cell transistors on the semiconductor substrate;

a plurality of contact plugs each buried between the adjacent cell transistors, and electrically connected to a diffusion layer between the adjacent cell transistors;

an interlayer dielectric film burying gaps between a plurality of the contact plugs;

a storage element provided not above the contact plugs but above the interlayer dielectric film;

a sidewall film covering at least a part of a side surface of the storage element, and overlapping with one of the contact plugs as viewed from above a surface of the semiconductor substrate; and

a lower electrode between a bottom of the storage element and the interlayer dielectric film and between the sidewall film and one of the contact plugs, the lower electrode electrically connecting the storage element to one of the contact plugs.

2. The device of claim 1, wherein, as the sidewall film and the lower electrode are viewed from above the surface of the semiconductor substrate, an external edge of the sidewall film is substantially equal in a shape to an external edge of the lower electrode.

3. The device of claim 2, wherein, as the sidewall film and the lower electrode are viewed from above the surface of the semiconductor substrate, the sidewall film and the lower electrode are generally circular, and a center of the sidewall film substantially matches a center of the lower electrode.

4. The device of claim 1, wherein, as the storage element and the lower electrode are viewed from above the surface of the semiconductor substrate, an external edge of the storage element is substantially equal in a shape to an external edge of the lower electrode.

5. The device of claim 2, wherein, as the storage element and the lower electrode are viewed from above the surface of the semiconductor substrate, an external edge of the storage element is substantially equal in a shape to an external edge of the lower electrode.

6. The device of claim 4, wherein, as the storage element and the lower electrode are viewed from above the surface of the semiconductor substrate, the storage element and the lower electrode are generally circular, and a center of the storage element substantially matches a center of the lower electrode.

7. The device of claim 1, wherein

as the storage element and the contact plugs are viewed from above the surface of the semiconductor substrate, the storage element is away from one of the contact plugs by a gap without overlapping with the contact plug, and

the lower electrode is provided on the gap.

8. The device of claim 1, wherein the sidewall film is a film made of at least one of silicon nitride, aluminum oxide, and zirconium oxide, or a composite film of silicon nitride, aluminum oxide, and zirconium oxide.

9. The device of claim 2, wherein the sidewall film is a film made of at least one of silicon nitride, aluminum oxide, and zirconium oxide, or a composite film of silicon nitride, aluminum oxide, and zirconium oxide.

10. The device of claim 1, further comprising an upper electrode on the storage element, wherein

the sidewall film is provided on a side surface of the upper electrode, a side surface of the storage element, and a part of an upper surface of the lower electrode.

11. The device of claim 2, further comprising an upper electrode on the storage element, wherein

the sidewall film is provided on a side surface of the upper electrode, a side surface of the storage element, and a part of an upper surface of the lower electrode.

12. The device of claim 1, wherein

the storage element comprises two magnetic layers and a tunnel barrier film provided between the two magnetic layers, and

the sidewall film is provided on an upper surface of the tunnel barrier film and on a side surface of one of the magnetic layers on the tunnel barrier film.

13. The device of claim 2, wherein

the storage element comprises two magnetic layers and a tunnel barrier film provided between the two magnetic layers, and

the sidewall film is provided on an upper surface of the tunnel barrier film and on a side surface of one of the magnetic layers on the tunnel barrier film.

14. The device of claim 10, wherein the upper electrode is a film made of at least one of Ta, titanium nitride, tungsten nitride, tantalum nitride, Pt, Ir, Ru, and Pd, or a composite film of Ta, titanium nitride, tungsten nitride, tantalum nitride, Pt, Ir, Ru, and Pd.

15. A method of manufacturing a semiconductor storage device comprising:

forming a plurality of cell transistors on a semiconductor substrate;

burying an interlayer dielectric film between gate electrodes of the cell transistors;

forming a contact plug between the adjacent cell transistors in such a manner that the contact plug is electrically connected to a diffusion layer between the adjacent cell transistors;

depositing a material of a lower electrode on the contact plug and the interlayer dielectric film;

forming a storage element on the material of the lower electrode in such a manner that the storage element does not overlap with the contact plug but with the interlayer dielectric film as the storage element is viewed from above a surface of the semiconductor substrate;

forming a sidewall film on at least a part of a side surface of the storage element in such a manner that the sidewall film overlaps with both the contact plug and the interlayer dielectric film as the sidewall film is viewed from above the surface of the semiconductor substrate; and

processing the material of the lower electrode using the sidewall film as a mask, and forming the lower electrode provided between a bottom of the storage element and the interlayer dielectric film and between the sidewall film and the contact plug.

16. The method of claim 15, wherein, as the sidewall film and the lower electrode are viewed from above the surface of the semiconductor substrate, the sidewall film and the lower electrode are generally circular and a center of the sidewall film substantially matches a center of the lower electrode.

17. The method of claim 15, wherein, as the storage element and the lower electrode are viewed from above the surface of the semiconductor substrate, the storage element and the lower electrode are generally circular, and a center of the storage element substantially matches a center of the lower electrode.

18. The method of claim 15, wherein

as the storage element and the contact plug are viewed from above the surface of the semiconductor substrate, the storage element is away from the contact plug by a gap without overlapping with the contact plug, and

the lower electrode is provided on the gap.

19. The method of claim 15, wherein the sidewall film is a film made of at least one of silicon nitride, aluminum oxide, and zirconium oxide, or a composite film of silicon nitride, aluminum oxide, and zirconium oxide.

20. The method of claim 15, wherein

the storage element comprises two magnetic layers and a tunnel barrier film provided between the two magnetic layers, and

the sidewall film is formed on an upper surface of the tunnel barrier film and on a side surface of one of the magnetic layers on the tunnel barrier film.