Dielectric compositions and methods to form the same

• US 6,673,274 B2
• Filed: 04/11/2001
• Issued: 01/06/2004
• Est. Priority Date: 04/11/2001
• Status: Expired due to Fees

• Current Assignee: Cabot Corporation
• Original Assignee: Cabot Corporation
• Inventors: Venigalla, Sridhar, Schultz, Dorran L.
• Primary Examiner(s): Gupta, Yogendra N.
• Assistant Examiner(s): Hamlin, Derrick G
• Application Number:
  US09/833,751
• Publication Number:
  US 20020171066A1
• Time in Patent Office: 1,000 Days
• Field of Search: 252/570, 252/572, 252/573, 361/321.4, 361/321.1, 361/321.2, 361/321.3, 361/312, 361/311
• US Class Current: 252/570
• CPC Class Codes: B32B 18/00 Layered products essentially comprising ceramics, e.g. refractory products
• CPC Class Codes: B32B 2311/22 Nickel or cobalt
• CPC Class Codes: C04B 2235/3205 Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3215 Barium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3236 Alkaline earth titanates
• CPC Class Codes: C04B 2235/3256 Molybdenum oxides, molybdates or oxide forming salts thereof, e.g. cadmium molybdate
• CPC Class Codes: C04B 2235/3262 Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
• CPC Class Codes: C04B 2235/3436 Alkaline earth metal silicates, e.g. barium silicate
• CPC Class Codes: C04B 2235/5445 submicron sized, i.e. from 0,1 to 1 micron
• CPC Class Codes: C04B 2235/549 the particle size being expressed by crystallite size or primary particle size
• CPC Class Codes: C04B 2237/346 Titania or titanates
• CPC Class Codes: C04B 2237/40 Metallic
• CPC Class Codes: C04B 2237/405 Iron metal group, e.g. Co or Ni
• CPC Class Codes: C04B 35/4682 based on BaTiO3 perovskite phase
• CPC Class Codes: C04B 35/62805 Oxide ceramics
• CPC Class Codes: C04B 35/62807 Silica or silicates
• CPC Class Codes: C04B 35/6281 Alkaline earth metal oxides
• CPC Class Codes: C04B 35/62815 Rare earth metal oxides
• CPC Class Codes: C04B 35/62818 : Refractory metal oxides
• CPC Class Codes: C04B 35/62886 : by wet chemical techniques
• CPC Class Codes: C04B 35/62894 : with more than one coating layer
• CPC Class Codes: C04B 35/62897 : Coatings characterised by their thickness
• CPC Class Codes: H01G 4/1227 : based on alkaline earth titanates

Abstract

The invention provides dielectric compositions and methods of forming the same. The dielectric compositions may be used to form dielectric layers in electronic devices such as multilayer ceramic capacitors (MLCCs) and, in particular, MLCCs which include base metal electrodes. The dielectric compositions include a barium titanate-based material and several dopants. The type and concentration of each dopant is selected to provide the dielectric composition with desirable electrical properties including a stable capacitance over a temperature range, a low dissipation factor, and a high capacitance. Preferably, MLCCs including dielectric layers formed with the composition satisfy X7R and/or X5R requirements.

Claims

1. A dielectric composition comprising:

a barium titanate-based material;

a rare earth metal compound;

a manganese compound;

an alkaline earth metal compound;

a hexavalent metal compound; and

a silicate-based compound,

wherein the barium titanate-based material comprises barium titanate-based particles and the barium titanate-based particles have a coating comprising at least one of the compounds.

4. The dielectric composition of claim 1, wherein the barium titanate-based material comprises barium titanate-based particles, the barium titanate-based particles having a coating comprising the rare earth metal compound.

5. The dielectric composition of claim 1, wherein the rare earth metal comprises between about 0.10% and about 2.5% of the total weight of the dielectric composition.

6. The dielectric composition of claim 5, wherein the rare earth metal comprises about 0.80% of the total weight of the dielectric composition.

7. The dielectric composition of claim 1, wherein the manganese compound comprises manganese oxide or manganese hydroxide.

8. The dielectric composition of claim 1, wherein the barium titanate-based material comprises barium titanate-based particles, the barium titanate-based particles having a coating comprising the manganese compound.

9. The dielectric composition of claim 1, wherein manganese comprises between about 0.01% and about 0.20% of the total weight of the dielectric composition.

10. The dielectric composition of claim 9, wherein the rare earth metal comprises about 0.05% of the total weight of the dielectric composition.

11. The dielectric composition of claim 1, wherein the alkaline earth metal compound comprises magnesium.

12. The dielectric composition of claim 11, wherein the rare earth metal compound comprises magnesium oxide or magnesium hydroxide.

13. The dielectric composition of claim 1, wherein the barium titanate-based material comprises barium titanate-based particles, the barium titanate-based particles having a coating comprising the alkaline earth metal compound.

14. The dielectric composition of claim 1, wherein the alkaline earth metal comprises between about 0.01% end about 0.50% of the total weight of the dielectric composition.

15. The dielectric composition of claim 14, wherein the alkaline earth metal comprises about 0.10% of the total weight of the dielectric composition.

16. The dielectric composition of claim 1, wherein the hexavalent metal compound comprises molybdenum.

17. The dielectric composition of claim 16, wherein the hexavalent metal compound comprises molybdenum oxide or molybdenum hydroxide.

18. The dielectric composition of claim 1, wherein the barium titanate-based material comprises barium titanate-based particles, the barium titanate-based particles having a coating comprising the hexavalent metal compound.

19. The dielectric composition of claim 1, wherein the hexavalent metal compound comprises between about 0.01% and about 0.20% of to total weight of the dielectric composition.

20. The dielectric composition of claim 19, wherein the hexavalent metal compound comprises about 0.05% of the total weight of the dielectric composition.

21. The dielectric composition of claim 1, wherein the silicate-based compound comprises barium silicate.

22. The dielectric composition of claim 1, wherein the barium titanate-based material comprises barium titanate-based particles, the barium titanate-based particles having a coating comprising barium silicate.

23. The dielectric composition of claim 1, wherein the silicate-based compound comprises between about 0.50% and about 5.0% of the total weight of the dielectric composition.

24. The dielectric composition of claim 1, wherein the silicate-based compound comprises less than about 1.75% of the total weight of the dielectric composition.

25. The dielectric composition of claim 1, wherein the silicate-based compound comprises less than about 1.35% of the total weight of the dielectric composition.

26. The dielectric composition of claim 1, wherein the barium titanate-based material comprises barium titanate.

27. The dielectric composition of claim 1, wherein the barium titanate-based material comprises particles having an average primary particle size of less than 0.5 micron.

28. The dielectric composition of claim 1, wherein the dielectric composition satisfies X5R specifications.

29. The dielectric composition of claim 1, wherein the dielectric composition satisfies X7R specifications.

2. The dielectric composition of claim E wherein the rare earth metal compound comprises yttrium.

3. The dielectric composition of claim 2, wherein the rare earth metal compound comprises yttrium oxide or yttrium hydroxide.

30. A dielectric composition comprising:

barium titanate particles having a coating;

yttrium comprising between about 0.10% and about 2.5% of the total weight of the dielectric composition;

manganese comprising between about 0.01% and about 0.20% of the total weight of the dielectric composition;

magnesium comprising between about 0.01% and about 0.50% of the total weight of the dielectric composition;

molybdenum comprising between about 0.01% and about 0.20% of the total weight of the dielectric composition; and

barium silicate comprising between about 0.50% and about 5.0% of the total weight of the dielectric composition.

31. A dielectric composition comprising barium titanate-based particles, the barium titanate-based particles having a coating comprising a rare earth metal compound, a manganese compound, an alkaline earth metal compound, a hexavalent metal compound, and a silicate-based compound.

32. The dielectric composition of claim 31, wherein the coating includes a plurality of chemically distinct layers.

33. A method of forming a dielectric composition comprising:

forming a coating on barium titanate-based particles, the coating comprising a rare earth metal compound, a manganese compound, an alkaline earth metal compound, a hexavalent metal compound, and a silicate-based compound.

34. The method of claim 33, wherein the rare earth metal compound comprises yttrium.

35. The method of claim 33, wherein the rare earth metal comprises between about 0.10 percent and about 2.5 percent of the total weight of the dielectric composition.

36. The method of claim 33, wherein manganese comprises between about 0.10 percent and about 0.20 percent of the total weight of the dielectric composition.

37. The method of claim 33, wherein the alkaline earth metal compound comprises magnesium.

38. The method of claim 33, wherein the alkaline earth metal comprises between about 0.01 percent and about 0.50 percent of the total weight of the dielectric composition.

39. The method of claim 33, wherein the hexavalent metal compound comprises molybdenum.

40. The method of claim 33, wherein the hexavalent metal compound comprises between about 0.01 percent and about 0.20 percent of the total weight of the dielectric composition.

41. The method of claim 33, wherein the silicate-based compound comprises barium silicate.

42. The method of claim 33, wherein the silicate-based compound comprises between about 0.50 percent and about 5.0 percent of the total weight of the dielectric composition.

43. The method of claim 33, wherein the barium titanate-based particles are barium titanate particles.