Atomic Layer Deposition (ALD) for Multi-Layer Ceramic Capacitors (MLCCs)
AssigneeForge Nano, Inc.
InventorsDaniel Higgs, Chris Gump, Karen Buechler, Jeanette Warner, Paul Nelson, David M. King, Arrelaine Dameron, James Trevey
Life of this patent
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Abstract
The use of Atomic Layer Deposition (ALD) and Molecular Layer Deposition (MLD) applied to powders and intermediates of the MLCC fabrication process can provide significant advantages. Coating metal particles within a defined range of ALD cycles is shown to provide enhanced oxidation resistance. Surprisingly, a very thin ALD layer was found to substantially increase sintering temperature.
Claims43
An intermediate structure for making an MLCC, comprising:
- a plurality of alternating dielectric green layers and electrode green layers;
- the dielectric green layers comprising particles of dielectric material or materials;
- the electrode green layers comprising particles of electrode materials coated by ALD with a sintering aid;
- wherein the powders of dielectric materials are not coated the sintering aid and wherein the sintering aid has the ability, at sufficiently high temperature, to migrate from the electrode layer into the dielectric layer where it aids in the sintering of the dielectric layers.
The structure of any of the preceding claims further comprising a powdered sintering aid dispersed in the dielectric layers.
The structure of any of the preceding claims wherein the powdered sintering aid comprises cations of Si, Li, B, Zn, Ti, Al, Bi and/or Y, in the form of an oxide, nitride, metal, semi-metal, metalloid, sulfide or halide, or combinations thereof.
The structure of any of the preceding claims wherein the sintering aid coating comprises cations of Si, Li, B, Zn, Ti, Al, Bi and/or Y, in the form of an oxide, nitride, metal, semi-metal, metalloid, sulfide or halide, or combinations thereof.
The structure of any of the preceding claims wherein the sintering aid coating comprises a first cation and a secondary cation having a valence state that is less than the first cation and having a sub-stoichiometric ratio of the second cation to the first cation.
An MLCC structure, comprising:
- a plurality of alternating electrode and dielectric layers;
- wherein the dielectric layers comprise a sintering aid or a phase enriched in sintering aid;
- wherein the dielectric layers have a thickness, an interior and two surface regions and an interior region sandwiched between the two surface regions;
- wherein each of the surfaces contact the electrode layers and are defined to have a thickness that is 20% of the thickness of the dielectric layer;
- wherein the sintering aid or phase enriched in sintering aid is unevenly distributed in the dielectric layers such that the concentration of sintering aid or phase enriched in sintering aid is higher in the surface regions than in the interior region.
An intermediate structure for making an MLCC, comprising:
- a plurality of alternating dielectric green layers and electrode green layers;
- the dielectric green layers comprising particles of dielectric material or materials;
- the electrode green layers comprising particles of a metal that is essentially free of titanium and comprising a coating consisting essentially of a rare earth oxide.
A powder composition, comprising:
- particles each having to pyrophoric metal core;
- a coating composition that renders the particles non-pyrophoric;
- wherein at least 90% of the particles, by number, have a particle size of 20 μm or less;
- wherein the coating composition has a calculated thickness of 1.5 mm or less or 1 nm or less, or between 0.5 and 1.5 nm. In some preferred embodiments, at least 90% of the particles, by number, have a particle size of from 2 to 20 μm;
- or 2 to 10 μm.
A method of making oxidation-resistant metal particles, comprising:
- optionally applying a vacuum to the metal particles to desorb water;
- exposing the metal particles about 25 to 100 alternating cycles of TMA and H2O.
A method of making oxidation-resistant metal particles, comprising:
- optionally applying a vacuum to the metal particles to desorb water;
- exposing the metal particles to 10 to 100 alternating cycles of ALD or MLD.
A method of making stabilized BaTiO3 particles, comprising providing BaTiO3 particles and coating the particles with alternating cycles of ALD to make a titania coating.
A powder composition, comprising:
- coated particles having a metal core and a coating composition;
- wherein the coated particles have a metal core to coating composition mass ratio that corresponds to a coating on the metal particles of 2 nm or less, or 1.5 nm or less, or 1.0 nm or less, or 0.5 to 2.0 nm, or 0.8 to 1.5 nm;
- wherein the powder composition has a first sintering temperature;
- and
- wherein an otherwise identical powder composition without the coating composition has a second sintering temperature;
- wherein the first temperature is at least 50, or at least 75, or at least 100, or from 50 to 200, or from 75 to 150, or 75 to 125° C. greater than the second temperature.
A powder composition, comprising at least 20 mass % of coated first particles having a metal core and a coating composition and at least 20 mass % of second particles;
- wherein the first and second particles have different compositions;
- wherein the second particles have a sintering temperature that is at least 50, or at least 75, or at least 100, or from 50 to 200, or from 75 to 150, or 75 to 125° C. greater than the sintering temperature of the metal core of the first particles;
- and
- wherein the coated first particles having a metal core and a coating composition have a sintering temperature that is at least 50, or at least 75, or at least 100, or from 50 to 200, or from 75 to 150, or 75 to 125° C. greater than the sintering temperature of the metal core of the first particles.
A method of fabricating a MLCC, comprising
- forming a slurry or paste comprising the powder composition of any of the above claims, forming a shaped article from the slurry or paste;
- optionally burning out a binder from the shaped article;
- and
- sintering the shaped article.
A stabilized zirconia powder, comprising:
- particles comprising a zirconia core that is stabilized with yttria;
- a yttria coating disposed over the core;
- wherein the yttria coating comprises at least 20%, at least 40%, at least 50% and up to about 63% Y.
A method of making a dielectric component, comprising:
- pressing a powder into a green body;
- subjecting the green body to an ALD or MLD treatment to deposit a sintering aid on the surface of particles in the interstices within the powder;
- heating the treated green powder to form a sintered dielectric component.
An intermediate structure, comprising:
- dielectric particles in contact with each other through points of contact;
- a sintering aid coating over the particles;
- wherein the sintering aid coating has a thickness and wherein the thickness is zero or very small at or near the points of contact and relatively thicker on surfaces of the particles away from the points of contact.
Dependencies are inferred from the claim text.