Thin film capacitor and method of fabrication thereof
Methods for fabricating a capacitor are provided. In the methods, a dielectric may be formed on a metal (e.g. nickel) substrate, and a copper electrode is formed thereon, followed by the thinning of the metal substrate from its non-coated face, and subsequently forming a copper electrode on the thinned, non-coated face of the substrate.
1. A method of fabricating a capacitor, comprising:
(a) providing a non-copper metal substrate that has first and second surfaces, wherein the non-copper metal substrate has a thickness in the range between about 40 microns and 120 microns;
(b) annealing the non-copper metal substrate;
(c) polishing the first surface of the non-copper metal substrate;
(d) coating the first surface of the non-copper metal substrate with a buffer layer;
(e) depositing a dielectric material on the first surface of the non-copper metal substrate to form a dielectric layer thereon, wherein the depositing the dielectric material is formed after the annealing the non-copper metal substrate, the polishing the first surface of the non-copper metal substrate, and the coating the first surface of the non-copper metal substrate with the buffer layer;
(f) depositing a first conductive material on the dielectric layer to form an electrode thereon;
(g) removing non-copper metal from the second surface of the non-copper metal substrate to reduce the thickness of the non-copper metal substrate; and
(h) depositing a second conductive material on the whole of the second surface of the non-copper metal substrate to form an electrode thereon.
2. The method according to claim 1 wherein the non-copper metal substrate has a uniform thickness.
3. The method according to claim 1 wherein the non-copper metal substrate comprises a foil.
4. The method according to claim 1 wherein the non-copper metal comprises nickel.
5. The method according to claim 1 wherein annealing the non-copper metal substrate comprises heating the non-copper metal substrate at a temperature greater than or equal to about 35% of its melting temperature for a period of time of at least about 30 minutes.
6. The method according to claim 1 wherein polishing the first surface of the non-copper metal substrate provides thereon a topographical roughness with an rms≦about 100 nm for a surface profilometric sampling length of about 71 microns.
7. The method according to claim 1 wherein the first and second conductive material deposited in step (f) and/or step (h) comprises copper.
8. The method according to claim 1 wherein step (g) comprises exposing the second surface of the non-copper metal substrate to an electrochemical bath.