# US 7,407,738 B2 · Fabrication and use of superlattice

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- Number: US 7,407,738 B2
- Document ID: US7407738B2
- Status: Granted
- Kind: B2
- Application number: 10/817,729
- Filed: 2004-04-02
- Published: 2005-10-06
- Granted: 2008-08-05
- Earliest claimed: 2004-04-02
- Inventors: Pavel Kornilovich; Peter Mardilovich; James Stasiak; Niranjan Thirukkovalur
- Web page: https://patentgrep.com/patent/US7407738B2

## CPC

- H10W 20/031: {of conductive parts of the interconnections}
- C23C 4/123: Spraying molten metal
- C23C 4/18: After-treatment
- C30B 29/68: Crystals with laminate structure, e.g. "superlattices"
- H05K 3/20: by affixing prefabricated conductor pattern {(H05K1/187, H05K3/046, H05K3/4658, H05K3/4682 takes precedence)}
- H10W 70/05: of insulating or insulated package substrates, or of interposers, or of redistribution layers (manufacture or treatment of leadframes H10W70/04)
- G03F 7/40: Treatment after imagewise removal, e.g. baking
- H05K 3/205: {using a pattern electroplated or electroformed on a metallic carrier}
- H05K 2203/0117: Pattern shaped electrode used for patterning, e.g. plating or etching
- H05K 2203/025: Abrading, e.g. grinding or sand blasting
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)

## Abstract

This disclosure relates to a system and method for fabricating and using a superlattice. A superlattice can be fabricated by applying alternating material layers on a ridge and then removing some of the alternating layers to expose edges. These exposed edges can be of nearly arbitrary length and curvature. These edges can be used to fabricate an array of nano-scale-width curved wires.

## Claims

### Claim 1

A method for forming a superlattice comprising:
forming a ridge aver a substrate surface, the ridge comprising sidewalk that are disposed substantially acutely relative to the substrate surface;
applying alternating layers of two or more materials over the ridge; and
removing part of the ridge and the alternating layers to expose edges of the alternating layers at the sidewalls of the ridge.

### Claim 2 (depends on 1)

The method of claim 1, wherein the act of forming the ridge comprises:
forming a first layer over the substrate surface;
forming a pattern over the first layer, the pattern having sidewalls disposed substantially acutely relative to the substrate surface; and
removing the first layer and the pattern sufficient to form the ridge from the first layer.

### Claim 3 (depends on 2)

The method of claim 2, wherein the act of removing the first layer and the pattern comprises etching the pattern and the first layer.

### Claim 4 (depends on 3)

The method of claim 3, wherein the first layer and the pattern comprise materials with different etch rates.

### Claim 5 (depends on 4)

The method of claim 4, wherein the etch rate of the first layer's material is slower than the etch rare of the pattern's material.

### Claim 6 (depends on 3)

The method of claim 3, wherein the act of forming the pattern comprises heating the pattern.

### Claim 7 (depends on 1)

The method of claim 1 , wherein the act of forming the ridge comprises:
forming the ridge with an electron beam.

### Claim 8

A method comprising:
applying an etchable surface layer over a substrate;
applying a photoresist layer over the etchable surface layer of the substrate;
exposing parts of the photoresist layer to radiation to create a pattern in the photoresist layer;
removing an unpatterened portion of the photoresist layer;
altering a slope of sidewalls of the patterned photoresist layer; and
etching the photoresist layer and the etchable surface layer to remove the photoresist layer and portions of the etchable surface layer, leaving a sloped, patterned ridge of the etchable surface layer, wherein the sloped patterned ridge is geometrically similar to the sloped, patterned photoresist layer;
applying alternating layers of two or more materials, one of the alternating layers having a thickness between one and one hundred nanometers, over the sloped, patterned ridge; and
removing the alternating layers from a top of the sloped, patterned ridge to expose edges of the alternating layers at the sloped sidewalls of the sloped, patterned ridge.

### Claim 9 (depends on 8)

The method of claim 8, wherein the act of applying the etchable surface layer comprises applying an oxide layer.

### Claim 10 (depends on 8)

The method of claim 8, wherein the act of applying the etchable surface layer comprises applying the etchable surface layer to a thickness from about one-half micron to five microns.

### Claim 11 (depends on 8)

The method of claim 8, wherein the etchable surface layer comprises a PECVD oxide or a nitride.

### Claim 12 (depends on 8)

The method of claim 8, wherein the etchable surface layer comprises a low-stress TEOS.

### Claim 13 (depends on 8)

The method of claim 8, wherein the act of altering the slope of the sidewalls comprises baking the patterned photoresist layer.

### Claim 14 (depends on 8)

The method of claim 8, wherein the act of altering the slope of the sidewalls comprises altering the slope to provide sidewalls defining about a thirty to ninety degree angle relative to the substrate.

### Claim 15 (depends on 8)

The method of claim 8, wherein the act of altering the slope of the sidewalls is performed until the sidewalls have about a forty-five degree angle from the substrate.

### Claim 16 (depends on 8)

The method of claim 8, wherein the act of etching removes the patterned, photoresist layer at a rate about fifty to 150 percent faster than the etchable surface layer.

### Claim 17 (depends on 8)

The method of claim 8, wherein the sloped, patterned ridge is non-linear.

### Claim 18 (depends on 8)

The method of claim 8 further comprising:
forming an array of wires having a thickness between one and one hundred nanometers over the exposed edges of one of the alternating layers.

### Claim 19

A method comprising:
applying alternating layers of two or more materials to a thickness between one and one hundred nanometers over a surface of a substrate having one or more non-linear ridges with substantially sloped side walls; and
planarizing the ridges and the alternating layers to expose edges of the alternating layers at the side walls of the ridges.

### Claim 20 (depends on 19)

The method of claim 19, wherein the act of applying comprises chemical-vapor depositing of the alternating layers.

### Claim 21 (depends on 19)

The method of claim 19, wherein one of the two or more materials is a conductor or semiconductor and another of the two or more materials is an insulator.

### Claim 22 (depends on 19)

The method of claim 19, wherein one of the two or more materials is a conductor having oxidation or nitridation rates, and another of the two or more materials is a conductor having different oxidation or nitridation rates.

### Claim 23 (depends on 19)

The method of claim 19, wherein one of the two or more materials has a different etch rate than another of the two or more materials.

### Claim 24 (depends on 19)

The method of claim 19, further comprising applying another layer of material over the alternating layers and wherein the planarizing stops when the other layer is removed.

### Claim 25 (depends on 19)

The method of claim 19, wherein the act of planarizing comprises chemical-mechanically polishing the ridges and alternating layers.

### Claim 26 (depends on 19)

The method of claim 19, further comprising forming an array of non-linear wires with a width between one and one hundred nanometers over the exposed edges atone or more of the alternating layers.

### Claim 27 (depends on 26)

The method of claim 26, wherein the act of forming comprises:
electrochemically depositing another material over the exposed edges of one or more of the alternating layers.

### Claim 28 (depends on 26)

The method of claim 26, wherein the act of forming comprises:
electrophoretically depositing charged objects over the exposed edges of one or more of the alternating layers.

### Claim 29 (depends on 26)

The method of claim 26, wherein the act of forming comprises:
charging ions of another material;
charging the exposed edges of one or more of the alternating layers; and
exposing the charged, exposed edges to the charged ions to build the other material up on the charged, exposed edges.

### Claim 30 (depends on 29)

The method of claim 29, wherein the other material comprises a polymer, a semiconductor, an oxide, a metal, or biological molecules.

### Claim 31 (depends on 19)

The method of claim 19, further comprising:
off-setting the exposed edges of one or more of the alternating layers to create a corrugated cross-section of the exposed edges of the alternating layers; and
stamping a malleable surface of a second substrate with the offset, exposed edges to create a negative of the off-set exposed edges on the malleable surface.

### Claim 32 (depends on 31)

The method of claim 31, further comprising forming an array of non-linear wires having a width between one and one hundred nanometers over the negative on the malleable surface.

### Claim 33 (depends on 31)

The method of claim 31, wherein the negative comprises an array of non-linear wires.

### Claim 34 (depends on 19)

The method of claim 19, wherein one of the materials is a conductor and another of the materials is an insulator, and further comprising:
off-setting the exposed edges of the conductive-material alternating layer from the exposed edges of the insulative-material alternating layer;
charging objects;
charging the off-set, exposed edges of the conductive-material alternating layer;
exposing the charged, off-set exposed edges to the charged objects to electrophoretically collect the objects in the off-set exposed edges.

### Claim 35

A method comprising:
shaping a surface layer on a substrate into an elongate ridge that extends along a long axis, the ridge being non-linear along the long axis and comprising a transverse cross section with substantially sloped sidewalls and a top;
applying alternating layers of two or more materials to a thickness between one and one hundred nanometers over the ridge; and
removing the alternating layers from the top of the ridge to expose edges of the alternating layers.

### Claim 36 (depends on 35)

The method of claim 35, wherein the act of shaping comprises:
applying a photoresist layer over the surface layer of the substrate;
exposing parts of the photoresist layer to radiation to create a non-linear pattern in the photoresist layer;
removing an unpatterned portion of the photoresist layer;
altering a slope of sidewalls of the non-linear, patterned photoresist layer; and
etching the sloped, non-linear, patterned photoresist layer and the surface layer to remove the non-linear, sloped, patterned photoresist layer and portions of the surface layer to create the non-linear ridge with the gene*ally substantially sloped sidewalls.

### Claim 37 (depends on 35)

The method of claim 35, wherein the act of shaping comprises:
stamping the surface layer with a negative of the elongate ridge effective to shape the surface layer to comprise the elongate ridge.

### Claim 38 (depends on 35)

The method of claim 35, wherein the act of shaping comprises:
applying an electron beam on the surface layer effective to shape the surface layer to comprise the elongate ridge.

### Claim 39 (depends on 35)

The method of claim 35, wherein the act of removing comprises:
planarizing the ridge and the alternating layers.

### Claim 40 (depends on 35)

The method of claim 35, further comprising:
forming a wire with a width between one and one hundred nanometers on one of the exposed edges of one of the alternating Layers.

### Claim 41 (depends on 35)

The method of claim 35, further comprising:
forming an array of non-linear wires over one or more of the exposed edges of one of the alternating layers.

### Claim 42

A method comprising: applying alternating layers of a first material and a second material over a surface of a substrate having one or mare non-linear ridges with substantially sloped side walls;
planarizing the ridges and the alternating layers to expose first edges of the first material layers and second edges of the second material layers at the side walls of the ridges to form a superlattice:
processing the exposed edges to offset the first edges to corrugate the alternating layers of the first material:
providing the superlattice having an array of co-parallel, curved corrugations between about one and one hundred nanometers wide; and
forming an array of co-parallel, curved wires between about one and one hundred nanometers wide using the array of co-parallel, curved corrugations.

### Claim 43 (depends on 42)

The method of claim 42, wherein the act of forming comprises depositing a material over the array of co-parallel, curved corrugations and further comprising transferring the array of curved wires onto a substrate.

### Claim 44 (depends on 42)

The method of claim 42, wherein the act of providing comprises providing the superlattice having the array of co-parallel, curved corrugations with at least one pitch of the co-parallel, curved corrugations being between about one and one hundred nanometers.

### Claim 45 (depends on 42)

The method of claim 42, wherein the act of providing comprises providing the superlattice with the co-parallel, curved corrugations having an elongate dimension between 1000 nanometers and 10 centimeters.

### Claim 46 (depends on 42)

The method of claim 42, wherein the act of forming comprises forming the array of co-parallel, curved wires having a pitch between about one and one hundred nanometers.

### Claim 47 (depends on 42)

The method of claim 42, wherein the act of providing comprises providing the superlattice having a second array of co-parallel, curved corrugations and the act of forming comprises forming a second array of co-parallel, curved wires.

### Claim 48 (depends on 47)

The method of claim 47, wherein the act of forming the first array of wires and the second array of wires comprises forming the first array non-parallel with the second array.

### Claim 49 (depends on 47)

The method of claim 47, wherein the act of forming the first array of wires and the second array of wires comprises forming the first array co-parallel with the second array.