Thin film capacitor

• US 5,262,920 A
• Filed: 05/13/1992
• Issued: 11/16/1993
• Est. Priority Date: 05/16/1991
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Yamamichi, Shintaro, Matsubara, Shogo, Sakuma, Toshiyuki
• Primary Examiner(s): Reynolds, Bruce A.
• Assistant Examiner(s): SWITZER, MICHAEL
• Application Number:
  US07/882,000
• Time in Patent Office: 552 Days
• Field of Search: 361/321, 361/311, 361/312, 361/313, 361/320, 361/304, 361/305, 29/25.42, 252/63.2, 252/8 T, 365/145, 357/51, 437/60
• US Class Current: 361/321.5
• CPC Class Codes: H01G 4/008 Selection of materials
• CPC Class Codes: H01G 4/06 Solid dielectrics
• CPC Class Codes: H01L 28/55 with a dielectric comprising a perovskite structure material
• CPC Class Codes: H01L 28/75 comprising two or more layers, e.g. comprising a barrier layer and a metal layer

Abstract

In a thin film capacitor in which a lower electrode,a dielectric film and an upper electrode are formed in order on a substrate, both the lower and upper electrodes are respectively formed with a first conductive layer made of Ti, Ta, Mo and W and a second conductive layer made of Pt, Pd, Rh and Al in this order from the substrate. In addition, a conductive metal oxide film such as made of PdO and others is formed, as required, at least between the lower electrode and the dielectric film or between the upper electrode and the dielectric film.

Claims

1. A thin film capacitor, comprising:

a lower electrode, a dielectric film, and an upper electrode formed in order on a substrate, said lower electrode and said upper electrode respectively having at least a first conductive film made of at least one layer of a high melting point metal selected from the group consisting of titanium, tantalum, molybdenum, tungsten, ruthenium, ruthenium silicide, ruthenium oxide, rhenium, rhenium silicide, rhenium oxide, osmium, osmium silicide, osmium oxide, rhodium, rhodium silicide and rhodium oxide,silicide compounds of these metals and titanium nitride, and a second conductive film made of at least one of platinum, palladium, rhodium and aluminum, said first conductive film being arranged closer to the substrate and said second conductive film being formed above the first conductive film, said dielectric film being made of a substance selected from the group consisting of BaTiO₃, SrTiO₃, PbTiO₃, PbZrO₃, LiNbO₃, Bi₄ Ti₃ O₁₂, and solid solutions of these substances, wherein a conductive metal oxide film is formed between said second conductive film of said lower electrode and said dielectric film.

2. A thin film capacitor as claimed in claim 1, wherein said substrate is one of:

(i) a semiconductor substrate which is impurity-doped as one of an n-type and a p-type;

(ii) a substrate made of a compound of at least two elements selected from the group consisting of Ga, As, In, P and A1; and

(iii) a solid solution substrate of one of Si and Ge.

3. A thin film capacitor as claimed in claim 1, wherein said substrate is a sapphire substrate.

4. A thin film capacitor as claimed in any one of claims 1, 2, or 3, wherein said conductive metal oxide film is made of PdO.

5. A thin film capacitor, comprising:

a lower electrode, a dielectric film, and an upper electrode formed in order on a substrate, said lower electrode and said upper electrode respectively having at least a first conductive film made of at least one layer of a high melting point metal selected from the group consisting of titanium, tantalum, molybdenum, tungsten, ruthenium, ruthenium silicide, ruthenium oxide, rhenium, rhenium silicide, rhenium oxide, osmium, osmium silicide, osmium oxide, rhodium, rhodium silicide and rhodium oxide, silicide compounds of these metals and titanium nitride, and a second conductive film made of at least one of platinum, palladium, rhodium and aluminum, said first conductive film being arranged closer to the substrate and said second conductive film being formed above the first conductive film, said dielectric film being made of a substance selected from the group consisting of BaTiO₃, SrTiO₃, PbTiO₃, PbZrO₃, LiNbO₃, Bi₄ Ti₃ O₁₂, and solid solutions of these substances, wherein a conductive metal oxide film is formed between said first conductive film of said upper electrode and said dielectric film.

6. A thin film capacitor as claimed in claim 5, wherein said substrate is one of:

(i) a semiconductor substrate which is impurity-doped as one of an n-type;

(ii) a substrate made of a compound of at least two elements selected from the group consisting of Ga, As, In, P and A1; and

(iii) a solid solution substrate of one of Si and Ge.

7. A thin film capacitor as claimed in claim 5, wherein said substrate is a sapphire substrate.

8. A thin film capacitor as claimed in any one of claims 5, 6 and 7, wherein said conductive metal oxide film is made of PdO.

9. A thin film capacitor, comprising:

a lower electrode, a dielectric film, and an upper electrode formed in order on a substrate, said lower electrode and said upper electrode respectively having at least a first conductive film made of at least one layer of a high melting point metal selected from the group consisting of titanium, tantalum, molybdenum, tungsten, ruthenium, ruthenium silicide, ruthenium oxide, rhenium, rhenium silicide, rhenium oxide, osmium, osmium silicide, osmium oxide, rhodium, rhodium silicide and rhodium oxide, silicide compounds of these metals and titanium nitride, and a second conductive film made of at least one of platinum, palladium, rhodium and aluminum, said first conductive film being arranged closer to the substrate and said second conductive film being formed above the first conductive film, said dielectric film being made of a substance selected from the group consisting of BaTiO₃, SrTiO₃, PbTiO₃, PbZrO₃, LiNbO₃, Bi₄ Ti₃ O₁₂, and solid solutions of these substances, wherein a conductive metal oxide film is formed between said second conductive film of said lower electrode and said dielectric film, and a conductive metal oxide film is formed between said first conductive film of said upper electrode and said dielectric film.

10. A thin film capacitor as claimed in claim 9, wherein said substrate is one of :

(i) a semiconductor substrate which is impurity-doped as one of an n-type and a p-type;

(ii) a substrate made of a compound of at least two elements selected from the group consisting of Ga, As, In, P and A1; and

(iii) a solid solution substrate of one of Si and Ge.

11. A thin film capacitor as claimed in claim 9, wherein said substrate is a sapphire substrate.

12. A thin film capacitor as claimed in any one of claims 9, 10, or 11, wherein each of the conductive metal oxide films is made of PdO.