Co-fired ceramic capacitor and method for forming ceramic capacitors for use in printed wiring boards
A capacitor structure is fabricated by forming a pattern of first dielectrics over a foil, forming first electrodes over the first dielectrics, and co-firing the first dielectrics and the first electrodes. Co-firing of the dielectrics and the electrodes alleviates cracking caused by differences in thermal coefficient of expansion (TCE) between the electrodes and the dielectrics. Co-firing also ensures a strong bond between the dielectrics and the electrodes. In addition, co-firing allows multi-layer capacitor structures to be constructed, and allows the capacitor electrodes to be formed from copper.
1. A capacitor structure, comprising:
a metallic foil;
at least one dielectric layer disposed over a portion of the foil; and
at least one first electrode disposed over a portion of the dielectric layer;
wherein upon cofiring the at least one dielectric layer with the at least one first electrode, the at least one dielectric layer exhibits a high dielectric constant, and the foil, the at least one dielectric layer and the at least one first electrode form a high capacitance capacitor.
2. The capacitor structure of claim 1 , wherein the metallic foil and the at least one first electrode comprises copper.
3. The capacitor structure of claim 1 , wherein the at least one dielectric layer comprises a high K glass and barium titanate.
4. The capacitor structure of claim 3 , wherein the at least one dielectric layer further comprises zirconium oxide.
5. The capacitor structure of claim 1 , incorporated into a device.
6. A multi-layer capacitor structure, comprising:
a metallic foil;
a first dielectric layer disposed over a portion of the foil;
a first electrode disposed over a portion of to dielectric layer and a portion of the foil;
a second dielectric layer disposed over a portion of the first dielectric layer and the first electrode; and
at least one second electrode disposed over a portion of the second dielectric layer and over a portion of the foil, wherein, upon cofiring the first and second dielectric layers with the first and second electrodes, and after etching the foil to form a trench, the dielectric exhibits a high dielectric constant and the foil, the first and second dielectric layers and the first and second electrodes form a high capacitance capacitor.
7. The capacitor structure of claim 6 , wherein the first dielectric layer and the first electrode are cofired prior to the addition of the second dielectric layer and the second electrode.
8. The capacitor structure of claim 6 , wherein the dielectric layer comprises a high K glass and barium titanate.
9. The capacitor structure of claim 8 , wherein the dielectric layer further comprises zirconium oxide.
10. The capacitor structure of claim 6 , wherein the metallic foil and the first electrode comprise copper.
11. The capacitor structure of claim 10 , wherein the second electrode comprises copper.
12. The capacitor structure of claim 6 , further comprising a third electrode formed over a portion of the second dielectric layer.
13. The capacitor structure of claim 6 , incorporated into a device.