Electrochemical method of making porous particles using a constant current density
First Claim
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1. A method of making porous particles comprising:
- providing a substrate having a surface;
forming a first nanoporous layer in the substrate by electrochemical etching using a constant current density;
continuing the etching by increasing the current density to form in the substrate a release layer, below the first nanoporous layer, having a porosity larger than that of the first nanoporous layer by electrochemical etching;
depositing a protective layer onto the substrate;
patterning the protective layer;
wherein the patterning of the protective layer determines the lateral shape of the porous particles;
etching the unprotected substrate to form pillars under the protective layer;
removing the remaining protective layer; and
releasing the one or more particles from the substrate,wherein the releasing comprises breaking the second porous layer and wherein the released one or more particles contain at least a portion of the first porous layer.
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Abstract
Provided is a particle that includes a first porous region and a second porous region that differs from the first porous region. Also provided is a particle that has a wet etched porous region and that does have a nucleation layer associated with wet etching. Methods of making porous particles are also provided.
7 Citations
26 Claims
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1. A method of making porous particles comprising:
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providing a substrate having a surface; forming a first nanoporous layer in the substrate by electrochemical etching using a constant current density; continuing the etching by increasing the current density to form in the substrate a release layer, below the first nanoporous layer, having a porosity larger than that of the first nanoporous layer by electrochemical etching; depositing a protective layer onto the substrate; patterning the protective layer;
wherein the patterning of the protective layer determines the lateral shape of the porous particles;etching the unprotected substrate to form pillars under the protective layer; removing the remaining protective layer; and releasing the one or more particles from the substrate, wherein the releasing comprises breaking the second porous layer and wherein the released one or more particles contain at least a portion of the first porous layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of making periodic stack structures of porous particles comprising:
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providing a substrate having a surface; depositing a first protective layer on the surface of the substrate; patterning a resistant layer onto the first protective layer;
wherein the patterning determines the lateral shape of the particles;removing the first protective layer from areas not covered by the resistant layer pattern; deep etching the unpatterned areas of the substrate to form trenches resulting in formation of pillars under the protective layer; depositing a second protective layer over the pillars and the trenches; exposing the top of the pillars by removing portions of the second protective layer; forming a first nanoporous layer in the pillar by electrochemical etching using a constant current density; continuing the etching by increasing the current density to form in the pillar a release layer, below the first porous layer, having a porosity larger than that of the first nanoporous layer; continuing the etching cycle to repeat the steps of forming the first nanoporous and the second porous layers at least once; and releasing the patterned one or more stack(s) of particles from the substrate, wherein the releasing comprises removing the second protective layer from the sides of the pillars and breaking the release layer and wherein the released one or more particles contain at least a portion of the first porous layer. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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25. A method of making porous particles comprising:
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providing a substrate having a surface; depositing a protective layer onto the surface of the substrate; patterning the protective layer onto the substrate;
wherein the patterning of the protective layer determines the lateral shape of the porous particles;etching the unprotected substrate to form a nanoporous layer by electrochemical etching using a constant current density; continuing the etching by increasing the current density to form in the substrate a release layer, below the first porous layer, having a porosity larger than that of the first porous layer; and releasing the patterned one or more particles from the substrate, wherein the releasing comprises removing the remaining protective layer and breaking the release layer and wherein the released one or more particles contain at least a portion of the first porous layer. - View Dependent Claims (26)
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Specification