Bottom electrode structure for dielectric capacitors

• US 5,708,302 A
• Filed: 04/26/1995
• Issued: 01/13/1998
• Est. Priority Date: 04/26/1995
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation), Symetrix Corporation
• Original Assignee: Matsushita Electric Corporation (Panasonic Holdings Corporation), Symetrix Corporation
• Inventors: Cuchiaro, Joseph D., Azuma, Masamichi, Paz De Araujo, Carlos A.
• Primary Examiner(s): Jackson, Jerome
• Assistant Examiner(s): Kelley, Nathan K.
• Application Number:
  US08/427,897
• Time in Patent Office: 993 Days
• Field of Search: 257/751, 257/769, 257/763, 257/753, 257/310
• US Class Current: 257/751
• CPC Class Codes: H01L 28/60 Electrodes

Abstract

An integrated circuit capacitor (20) includes a bottom electrode structure (24) having an adhesion metal portion (34), a noble metal portion (36), and a second noble metal layer (40). A process of manufacture includes annealing the adhesion metal portion (34) and the noble metal portion (36) prior to the deposition of second noble metal layer (40) for purposes of forming barrier region (38). The electrode (24) preferably contacts metal oxide layer (26), which is made of a perovskite or perovskite-like layered superlattice material. A temporary capping layer (59) is formed and removed in manufacture, which serves to increase polarization potential from the device by at least 40%.

Claims

1. A thin-film electrode device for use in integrated circuits, comprising:

a substrate;

a bottom electrode supported by said substrate and including an interdiffusion region including a stabilized lattice having a mixture of annealed adhesion metal and noble metal moieties,

said mixture of annealed adhesion metal and noble metal moieties produced according to a method including the steps of depositing of an adhesion metal layer on said substrate, a noble metal layer on said

adhesion metal layer, and a temporary capping layer on said noble metal layer, thereafter

annealing said adhesion metal layer, said noble metal layer, and said temporary layer, in simultaneous fashion, and thereafter removing said temporary layer; and

a noble metal capping layer produced by depositing said noble metal capping layer over said region after said annealing step.

2. The device as set forth in claim 1, said bottom electrode having an abrupt change in a diffusion gradient for said adhesion metal through said interdiffusion region, said abrupt change characterized by being caused by said step of removing said temporary layer from a surface of said interdiffusion region.

3. The device as set forth in claim 2, said substrate including an isolation layer adjoining said bottom electrode.

4. The device as set forth in claim 1, said bottom electrode interdiffusion region having a first average concentration of at least one diffusible moiety selected from the group consisting of adhesion metal moieties, substrate moieties, and mixtures thereof, said noble metal capping layer having a second average concentration of said diffusible moiety less than said first average concentration.

5. The device as set forth in claim 4, said diffusible moiety being titanium adhesion metal.

6. The device as set forth in claim 5, said noble metal moieties of said interdiffusion region and said noble metal capping layer both including an identical type of noble metal.

7. The device as set forth in claim 6, said noble metal moieties of said interdiffusion region and said noble metal capping layer both including platinum.

8. The device as set forth in claim 1, said adhesion metal moieties of said interdiffusion region including titanium.

9. The device as set forth in claim 1, said adhesion metal moieties of said interdiffusion region including tantalum.

10. The device as set forth in claim 1, said interdiffusion region consisting essentially of platinum and titanium.

11. The device as set forth in claim 1, said noble metal capping layer consisting essentially of platinum.

12. The device as set forth in claim 1, further including:

a metal oxide layer opposite said substrate across said noble metal capping layer and said interdiffusion region, said metal oxide layer including a metal oxide material selected from the group consisting of ferroelectric metal oxides, dielectric metal oxides having a dielectric constant greater than or equal to that of silicon dioxide, and combinations thereof; and

a top electrode opposite said first noble metal capping layer across said second metal oxide layer.

13. The device as set forth in claim 12, said metal oxide layer including a barium strontium titanate material.

14. The devices as set forth in claim 13, said barium strontium titanate material being essentially free of silicon and silicon dioxide.

15. The device as set forth in claim 14, said barium strontium titanate material including an average empirical formula of Ba₀.7 Sr₀.3 TiO₃.

16. The device as set forth in claim 12, said metal oxide layer including a layered superlattice material compound.

17. The device as set forth in claim 16, said layered superlattice material compound including strontium bismuth tantalate.

18. The device as set forth in claim 17, said strontium bismuth tantalate material including an average empirical formula of SrBi₂ Ta₂ O₉.

19. A device produced according to a method comprising the steps of:

depositing titanium metal on a substrate;

depositing a platinum metal on said adhesion layer;

interdiffusing said titanium metal and said platinum metal to provide a barrier region by heating said adhesion metal portion end said noble metal portion to a first anneal temperature ranging from 450°

C. to 850°

C.;

cooling said diffusion barrier region to stabilize a lattice therein;

thereafter

amassing a noble metal layer upon said diffusion barrier layer;

forming a temporary layer on said noble metal layer by

contacting said noble metal layer with a liquid precursor solution to form a thin precursor film, said liquid precursor solution having a plurality of metal moieties in effective amounts for yielding a metal oxide layered superlattice material upon thermal treatment in an oxygen atmosphere, and

annealing said thin precursor film to yield said metal oxide by heating said thin precursor film in oxygen to a temperature ranging from about 600°

C. to about 850°

C.;

removing said temporary layer; and

forming a layered superlattice material metal oxide material on said second noble metal layer after removal of said temporary layer.

20. The device as set forth in claim 19, wherein said device has a 3V polarization potential of at least about 40% greater than an identical device prepared without said forming and removing steps.