Dielectric oxide materials

• US 7,294,598 B2
• Filed: 12/30/2005
• Issued: 11/13/2007
• Est. Priority Date: 12/30/2004
• Status: Active Grant

• Current Assignee: Stmicroelectronics France (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Inventors: Gervais, Monique, Brize, Virginie
• Primary Examiner(s): Brunsman; David M
• Application Number:
  US11/322,516
• Publication Number:
  US 20060148636A1
• Time in Patent Office: 683 Days
• Field of Search: 501/1, 501/136, 264/614, 264/615, 264/620, 264/621, 264/624
• US Class Current: 501/136
• CPC Class Codes: C01G 23/003 Titanates C01G23/001 takes precedence
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3281 Copper oxides, cuprates or oxide-forming salts thereof, e.g. CuO or Cu2O
• CPC Class Codes: C04B 2235/6023 Gel casting
• CPC Class Codes: C04B 2235/77 Density
• CPC Class Codes: C04B 2235/786 Micrometer sized grains, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/9661 Colour
• CPC Class Codes: C04B 35/462 based on titanates
• CPC Class Codes: C04B 35/465 based on alkaline earth metal titanates
• CPC Class Codes: H01B 3/12 ceramics
• CPC Class Codes: H01G 4/1218 based on titanium oxides or titanates H01G4/1245 takes precedence

Abstract

A material made of a dielectric oxide of type Ca_0.25Cu_0.75TiO₃ having a dielectric constant greater than 3,000.

Claims

1. A material made of a dielectric oxide of type Ca_0.25Cu_0.75TiO₃ having a dielectric constant greater than 4,000 and a grain size at least equal to 2 μ

m.

2. A material, comprising:

a Ca_0.25Cu_0.75TiO₃ ceramic having a grain size that is greater than 1.7 μ

m and a dielectric constant greater than 4,000.

3. The material of claim 2 wherein the ceramic has a grain size that is greater than or equal to approximately 2 μ

m.

4. The material of claim 2 wherein the ceramic has a grain size of approximately 4.1±

1.8 μ

m.

5. The material of claim 2 wherein the ceramic comprises CaCu₃Ti₄O₁₂.

6. The material of claim 2 wherein the ceramic has a density of approximately 80%.

7. An integrated circuit, comprising:

a layer of Ca_0.25Cu_0.75TiO₃ ceramic having a grain size that is greater than 1.7 μ

m and a dielectric constant greater than 4,000.

8. An electronic system, comprising:

an integrated circuit including a layer of Ca_0.25Cu_0.75TiO₃ ceramic having a grain size that is greater than 1.7 μ

m and a dielectric constant greater than 4,000.

9. A method for shaping a dielectric oxide, comprising the steps of:

calcinating a gel comprising the oxide components and a polymer at a minimum temperature capable of obtaining a crystal system;

reducing to powder the calcinations product;

adding a liquid binder to the powder; and

drying the mixture of the binder and of the powder and crushing the mixture during the drying.

10. The method of claim 9, further comprising, after the drying step, an isostatic pressing and a sintering of the dried product.

11. The method of claim 9, wherein the drying step comprises the steps of:

partially drying the mixture at a relatively low temperature; and

completely drying the mixture at a relatively high temperature.

12. The method of claim 11, wherein the oxide powder is of Ca_0.25Cu_0.75TiO₃ type, the calcinations step being performed at 500°

C. for twenty hours, the binder being polyvinylic alcohol, the partial drying being performed in a drying chamber at 60°

C. and the full drying being performed in a furnace at 200°

C. for at least four hours.

13. The method of claim 9, wherein the crushing is continuously performed during the drying.

14. The method of claim 9, wherein the crushing is performed at regular intervals during the drying.

15. A method, comprising:

calcinating a gel at a temperature sufficient to yield a crystal system, the gel including an oxide and a polymer;

forming a powder from the calcinated gel;

mixing the powder with a binder;

drying the mixture of the powder and the binder; and

crushing the mixture.

16. The method of claim 15, wherein the gel comprises calcium, copper and titanium.

17. The method of claim 15 wherein calcinating the gel comprises calcinating the gel at a temperature of approximately 500°

C. or greater.

18. The method of claim 15 wherein calcinating the gel comprises calcinating the gel for approximately twenty hours.

19. The method of claim 15 wherein forming a powder from the calcinated gel comprises mixing the calcinated gel with zirconia and isopropanol balls.

20. The method of claim 15 wherein mixing the powder with the binder comprises mixing the powder with a liquid binder.

21. The method of claim 15 wherein drying the mixture comprises:

drying the mixture for a first time period at a first temperature; and

drying the mixture for a second time period at a second temperature.

22. The method of claim 15 wherein crushing the mixture comprises crushing the mixture substantially continuously.

23. The method of claim 15 wherein crushing the mixture comprises periodically crushing the mixture.

24. The method of claim 15 wherein crushing the mixture comprises crushing the mixture while drying the mixture.

25. The method of claim 15, further comprising isostatically pressing and sintering the dried and crushed powder at approximately 1000°

C. for approximately twenty hours into a mass having a predetermined shape.