Reactively formed integrated capacitors on organic substrates and fabrication methods

• US 20060269762A1
• Filed: 02/27/2006
• Published: 11/30/2006
• Est. Priority Date: 03/02/2005
• Status: Abandoned Application

• Current Assignee: Devarajan Balaraman, Isaac R. Abothu, Markondeya Raj Pulugurtha, Rao Tummala
• Original Assignee: Devarajan Balaraman, Isaac R. Abothu, Markondeya Raj Pulugurtha, Rao Tummala
• Inventors: Abothu, Isaac R., Pulugurtha, Markondeya Raj, Tummala, Rao, Balaraman, Devarajan
• Application Number:
  US11/363,334
• Publication Number:
  US 20060269762A1
• Time in Patent Office: Days
• US Class Current: 428/457
• CPC Class Codes: H01G 4/10 Metal-oxide dielectrics H01G4/085 takes precedence
• CPC Class Codes: H01G 4/33 Thin- or thick-film capacitors thin- or thick-film circuits H01L27/00; capacitors without a potential-jump or surface barrier specially adapted for integrated circuits, details thereof, multistep manufacturing processes therefor H01L28/40
• CPC Class Codes: H05K 1/162 incorporating printed capacitors
• CPC Class Codes: H05K 2201/0175 Inorganic, non-metallic layer, e.g. resist or dielectric for printed capacitor
• CPC Class Codes: H05K 2201/0355 Metal foils
• CPC Class Codes: H05K 2201/09763 Printed component having superposed conductors, but integrated in one circuit layer
• CPC Class Codes: H05K 2203/121 Metallo-organic compounds
• CPC Class Codes: H05K 3/388 by the use of a metallic or inorganic thin film adhesion layer
• CPC Class Codes: Y10T 428/31678 Of metal

Abstract

Disclosed are organic-compatible thin film processing techniques with reactive (such as Ti) layers for embedding capacitors into substrates. Hydrothermal synthesis allows direct deposition of high-k films with capacitance density of about 1 μF/cm² on organic substrates. This is done by reactively growing a high-k film from Ti foil/Ti-coated copper foil/Ti precursor-coated organic substrate in an alkaline barium ion bath. Alternatives may be used to address multiple coatings, low temperature baking, low temperature pyrolysis with oxygen plasma, etc. Sol-gel and RF-sputtering assisted by a reaction with the intermediate layer and a foil transfer process may be used to integrate perovskite thin films with a capacitance in the range of 1-5 μF/cm². Thermal oxidation of titanium foil/Ti-coated copper foil/Ti-coated organic substrate with a copper conductive layer is also a reactively grown high-k film process for integrating capacitance of hundreds of nF with or without using a foil transfer process.

Claims

1. A capacitor integrated onto a substrate or foil formed by:

reacting a metal or precursor layer using a hydrothermal reaction, thermal oxidation or solid-state reaction with a deposited layer, to create a high dielectric constant film on the substrate that comprises the integrated capacitor.

2. The capacitor recited in claim 1 wherein the metal or precursor layer is selected from the group including titanium, niobium, zinc, chromium, silicon, nickel, tantalum, vanadium and derivative organic precursors thereof.

3. The capacitor recited in claim 1 wherein the high dielectric constant film is formed by hydrothermally reacting a metallic film with an alkaline bath.

4. The capacitor recited in claim 1 wherein the high dielectric constant film comprises a synthesized fine-grained high k film formed by hydrothermally reacting a titanium-organic compound with an alkaline bath.

5. The capacitor recited in claim 1 wherein the hydrothermal film is baked at about 250°

C. in air, oxygen, or nitrogen to improve dielectric properties.

6. The capacitor recited in claim 3 wherein the hydrothermally formed film is treated with oxygen plasma to improve dielectric properties.

7. The capacitor recited in claim 3 the hydrothermally formed film comprises multiple hydrothermally formed thin films to prevent cracking.

8. The capacitor recited in claim 1 further comprising baking the high dielectric constant film at temperatures compatible with organics.

9. The capacitor recited in claim 1 wherein organic content of the high dielectric constant film is removed using oxygen plasma at relatively low temperatures.

10. The capacitor recited in claim 1 which is formed by:

laminating titanium foil or titanium coated copper foil onto an organic substrate;

treating the titanium precursor coating on an organic substrate using plasma; and

immersing the organic substrate and laminated foil in barium hydroxide solution at a predetermined temperature and for a predetermined time period.

11. The capacitor recited in claim 1 wherein the high dielectric constant film comprises a thermally-oxidized metal on an organic substrate or thermally oxidized metal foil that is later transferred onto an organic substrate.

12. The method recited in claim 11 wherein the thickness of the high dielectric constant film is controlled by the time and temperature of the thermal oxidation.

13. The method recited in claim 11 wherein the metal foil comprises multiple layers that reactively grow on the metal foil with properties having a desired performance level in terms of thermal stability.

14. The capacitor recited in claim 11 wherein the thermally-oxidized metal foil is selected from the group including titanium, nickel, vanadium and chromium, tantalum, zinc, and niobium.

15. The capacitor recited in claim 1 wherein the high dielectric constant film comprises a thermally oxidizable metal or precursor coating disposed on a metal foil that is later transferred to an organic substrate.

16. The capacitor recited in claim 1 which is formed using a reactive layer by:

preparing a metallorganic precursor solution using sol-gel synthesis;

spin-coating the precursor solution onto the substrate having a reactive layer formed thereon to produce a film;

pyrolyzing the film; and

heat treating the film to produce a high dielectric constant film by reacting the precursor with the reactive layer underneath to form the high dielectric constant film comprising an integrated capacitor.

17. The method recited in claim 16 wherein heat treating and reaction is performed in an air, oxygen, nitrogen or hydrogen environment directly on a organic substrate or on a foil which is then transferred onto an organic substrate.

18. The capacitor recited in claim 1 wherein the high dielectric constant film comprises a metallorganic precursor solution derived high dielectric constant film with the a reactive intermediate layer that also protects the underneath metal.

19. The method recited in claim 18 wherein the precursor solution is prepared by:

dissolving barium in 2-methoxyethanol solvent;

refluxing the dissolved barium in an argon atmosphere;

to produce a precursor solution;

cooling the precursor solution to room temperature;

adding a stoichiometric amount of titanium (IV) isopropoxide to the precursor solution; and

refluxing the precursor solution in argon atmosphere to obtain a barium titanate precursor solution.

20. The method recited in claim 19 further comprising:

selectively adding dopant precursors and/or metals to the precursor solution containing barium and titanium (IV) isopropoxide prior to final refluxing.

21. The capacitor recited in claim 1 which is formed by forming a sputtered high dielectric constant film on a metal foil with a reactive intermediate layer, where the sputtered film reacts with the reactive intermediate layer by solid state reactions and forms the high dielectric constant layer.

22. The method recited in claim 21 where the sputtered film is a insulator that reacts with the intermediate layer to form the high dielectric constant layer.

23. The method recited in claim 21 where the sputtered film is a metal that reacts with the intermediate layer to form the high dielectric constant layer.

24. The method recited in claim 21 where the sputtered film and the reactive layer oxidize to form the high dielectric constant layer.

25. The method recited in claim 21 where the sputtered film and the reactive layer comprise dopants to improve film properties.