High-dielectric constant thin film metal oxides on silicon wafers for capacitor applications and methods of manufacture
A method of fabrication of high-k paraelectric metal oxide films at low temperatures utilizing ordered mesoporous metal oxide thin films synthesized by organic templating methodology. The process consisting of (a) chemical solution deposition of periodic ordered mesoporous structures containing high-k metal oxide films, (b) removal of organic template additives, (c) infiltration of the pores with an appropriate second phase, and (d) low temperature thermal and/or annealing of infiltrated films.
1. A method of manufacturing a high-k film, comprising the steps of:
providing an organic template;
synthesizing an oxide film comprising a mesoporous binder phase material in the presence of the organic template;
thereafter removing the organic template from the oxide film;
providing a liquid material comprising a liquid precursor for a high-k phase material;
subsequent to the removal of the organic template, diffusing the precursor for the high-k phase material into the oxide film;
forming a high-k phase material from the liquid precursor; and
thereafter hardening the high-k phase material, thus obtaining a high-k film comprising components of the oxide film and the high-k phase material.
2. The method according to claim 1 including the additional step of densifying the mesoporous binder phase material after hardening the high-k phase material.
3. The method according to claim 1 wherein the binder phase material is selected from the group consisting of Si0 2 , boro-phospho-silicate (BPS) glass, ZnO, Zn0-Si0 2 , Ti0 2 , Ti0 2 /Si0 2 , Ta 2 0 5 , and Ta 2 0 5 —Ti0 2 -Si0 2 .
4. The method according to claim 1 wherein the organic template is a surfactant.
5. The method according to claim 1 wherein the organic template is removed by heating to a temperature between about 350° C. and about 450° C.
6. The method according to claim 1 wherein the organic template is removed by extraction with super critical C0 2 .
7. The method according to claim 1 wherein the organic template is removed by exposure to UV light followed by heating to a temperature of between about 250° C. and about 300° C.
8. The method according to claim 1 wherein the oxide film is synthesized from a first solution comprising 3.0 g 2-methoxyethanol, 0.55 g titanium isopropoxide, 2.5 g 20% barium isopropoxide in isopropanol, 2.0 g ethanol, and 0.2 g Pluronic P123, and 0.15 g acetylacetone stirred to dissolution; and another solution of 0.10 g ethanol and 0.08 g 1.0 F acetic acid which is added to the first solution.
9. The method according to claim 1 wherein the oxide film is synthesized from a first solution comprising 0.18 acetylacetone, 1.0 g tantalum ethoxide, 1.33 g isopropanol which is allowed to sit overnight (minimum); and a solution of 0.42 g P123, 4.66 g 2-propanol, and 0.05 g H 2 0, acidified to pH-2 with ethanolic HCl that is added to the first solution the next day and the mix is stirred for an hour.
10. The method according to claim 1 wherein the high-k precursor is diffused into the oxide film's binder phase after removing the organic template; the high-k phase material is formed; and the overall structure is condensed and hardened by annealing at between about 700° C. and about 900° C.
11. The method of claim 4 , wherein the surfactant is a polymeric surfactant.
12. The method of claim 11 , wherein the polymeric surfactant is a block copolymer of poly(ethylene oxide)-polypropylene oxide).