Periodic layered structures and methods therefor

Abstract

A periodic layered structure having physical and chemical properties varying periodically at least along a direction perpendicular to its layers is made by providing a substrate, depositing a quantity of non-porous electrochemically oxidizable material over the substrate, at least partially anodizing the non-porous electrochemically oxidizable material, and repeating similar steps until a layered structure having a desired periodicity and a desired total structure thickness is completed.

1 . A method for fabricating a layered structure having physical and chemical properties varying periodically at least along a direction perpendicular to its layers, the method comprising the steps of: 
 a) providing a substrate,    b) depositing a quantity of non-porous electrochemically oxidizable material over the substrate to form a first layer having a first-layer thickness,    c) anodizing the electrochemically oxidizable material until a second-layer thickness of oxide is formed, and    d) repeating alternately the steps b) of depositing and c) of anodizing until a layered structure having a desired periodicity and a desired structure thickness is completed.    
   
   
       2 . The method of  claim 1 , wherein the electrochemically oxidizable material comprises a non-porous material selected from the list consisting of Al, Ta, Nb, W, Bi, Sb, Ag, Cd, Fe, Mg, Sn, Zn, Ti, Cu, Mo, Hf, Zr, Ti, V, Au, and Cr, and alloys, mixtures, and combinations thereof.  
   
   
       3 . The method of  claim 1 , wherein the electrochemically oxidizable material comprises non-porous silicon (Si).  
   
   
       4 . The method of  claim 1 , wherein the periodic layered structure comprises a superlattice.  
   
   
       5 . The method of  claim 1 , wherein the first-layer thickness of the first layer is greater than or about equal to two nanometers (2 nm).  
   
   
       6 . The method of  claim 1 , wherein the periodicity is greater than or about equal to five nanometers (5 nm).  
   
   
       7 . The method of  claim 1 , wherein the substrate is substantially planar.  
   
   
       8 . The method of  claim 1 , wherein the steps are performed in the order recited.  
   
   
       9 . The method of  claim 1 , further comprising the step of planarizing the first layer.  
   
   
       10 . The periodic layered structure made by the method of  claim 1 .  
   
   
       11 . A method for fabricating a layered structure having physical and chemical properties varying periodically at least along a direction perpendicular to its layers, the method comprising the steps of: 
 a) providing a substrate,    b) depositing a quantity of a first non-porous electrochemically oxidizable material over the substrate to form a first layer having a first-layer thickness,    c) anodizing the first layer until a desired thickness of first oxide is formed,    d) depositing a quantity of a second non-porous electrochemically oxidizable material over the first oxide,    e) anodizing the second non-porous electrochemically oxidizable material until a desired thickness of second oxide is formed, and    f) repeating the previous four steps b), c), d), and e) a number of times until a layered structure having a desired periodicity and a desired structure thickness is completed.    
   
   
       12 . The method of  claim 11 , wherein the first non-porous electrochemically oxidizable material and the second non-porous electrochemically oxidizable material comprise different materials.  
   
   
       13 . The method of  claim 11 , wherein each of the first non-porous electrochemically oxidizable material and the second non-porous electrochemically oxidizable material comprises a material selected from the list consisting of Al, Ta, Nb, W, Bi, Sb, Ag, Cd, Fe, Mg, Si, Sn, Zn, Ti, Cu, Mo, Hf, Zr, Ti, V, Au, and Cr, and alloys, mixtures, and combinations thereof.  
   
   
       14 . The method of  claim 11 , wherein the first non-porous electrochemically oxidizable material comprises aluminum.  
   
   
       15 . The method of  claim 11 , wherein the first non-porous electrochemically oxidizable material comprises tantalum.  
   
   
       16 . The method of  claim 11 , wherein the second non-porous electrochemically oxidizable material comprises aluminum.  
   
   
       17 . The method of  claim 11 , wherein the second non-porous electrochemically oxidizable material comprises tantalum.  
   
   
       18 . The method of  claim 11 , wherein the first non-porous electrochemically oxidizable material and the second non-porous electrochemically oxidizable material comprise the same material.  
   
   
       19 . The method of  claim 18 , wherein both the first non-porous electrochemically oxidizable material and the second non-porous electrochemically oxidizable material comprise the same material selected from the list consisting of Al, Ta, Nb, W, Bi, Sb, Ag, Cd, Fe, Mg, Si, Sn, Zn, Ti, Cu, Mo, Hf, Zr, Ti, V, Au, and Cr, and alloys, mixtures, and combinations thereof.  
   
   
       20 . The method of  claim 11 , wherein the periodic layered structure comprises a superlattice.  
   
   
       21 . The method of  claim 11 , wherein the first-layer thickness of the first layer is greater than or about equal to two nanometers (2 nm).  
   
   
       22 . The method of  claim 11 , wherein the periodicity is greater than or about equal to five nanometers (5 nm).  
   
   
       23 . The method of  claim 11 , wherein the substrate is substantially planar.  
   
   
       24 . The method of  claim 11 , wherein the steps are performed in the order recited.  
   
   
       25 . The method of  claim 11 , further comprising the step of planarizing the first layer.  
   
   
       26 . The method of  claim 11 , further comprising the step of planarizing the second layer.  
   
   
       27 . The periodic layered structure made by the method of  claim 11 .  
   
   
       28 . A method for fabricating a layered structure having physical and chemical properties varying periodically at least along a direction perpendicular to its layers, the method comprising the steps of: 
 a) providing a substrate,    b) depositing a quantity of a first non-porous electrochemically oxidizable material over the substrate to form a first layer having a first-layer thickness,    c) anodizing the first non-porous electrochemically oxidizable material until a desired thickness of first oxide is formed, and    d) repeating steps b) and c) a number of times respectively for a number n of non-porous electrochemically oxidizable materials until a layered structure having a desired periodicity and a desired structure thickness is completed.    
   
   
       29 . The method of  claim 28 , wherein each of the non-porous electrochemically oxidizable materials of the number n of non-porous electrochemically oxidizable materials comprises a material selected from the list consisting of Al, Ta, Nb, W, Bi, Sb, Ag, Cd, Fe, Mg, Si, Sn, Zn, Ti, Cu, Mo, Hf, Zr, Ti, V, Au, and Cr, and alloys, mixtures, and combinations thereof.  
   
   
       30 . The method of  claim 28  wherein the non-porous electrochemically oxidizable materials of the number n of non-porous electrochemically oxidizable materials all comprise the same material.  
   
   
       31 . The method of  claim 28  wherein the non-porous electrochemically oxidizable materials of the number n of non-porous electrochemically oxidizable materials comprise at least two different materials.  
   
   
       32 . The method of  claim 28  wherein the non-porous electrochemically oxidizable materials of the number n of non-porous electrochemically oxidizable materials comprise a number m of different materials, wherein m is less than n.  
   
   
       33 . The method of  claim 28  wherein the non-porous electrochemically oxidizable materials of the number n of non-porous electrochemically oxidizable materials comprise n different materials.  
   
   
       34 . The method of  claim 28 , wherein the periodic layered structure comprises a superlattice.  
   
   
       35 . The method of  claim 28 , wherein the first-layer thickness of the first layer is greater than or about equal to two nanometers (2 nm).  
   
   
       36 . The method of  claim 28 , wherein the periodicity is greater than or about equal to five nanometers (5 nm).  
   
   
       37 . The method of  claim 28 , wherein the substrate is substantially planar.  
   
   
       38 . The method of  claim 28 , wherein the steps are performed in the order recited.  
   
   
       39 . The method of  claim 28 , further comprising the step of planarizing the first layer.  
   
   
       40 . The method of  claim 28 , further comprising the step of planarizing the m th  layer, wherein m is less than or equal to n.  
   
   
       41 . The periodic layered structure made by the method of  claim 28 .  
   
   
       42 . A method for fabricating a layered structure having physical and chemical properties varying periodically at least along a direction perpendicular to its layers, the method comprising the steps of: 
 a) providing a substrate,    b) depositing a quantity of a first non-porous electrochemically oxidizable material over the substrate to form a first electrochemically oxidizable layer having a first-layer thickness,    c) anodizing the first electrochemically oxidizable layer fully until a homogeneous layer of first oxide is formed, thereby substantially replacing the first electrochemically oxidizable layer with the first oxide,    d) depositing a quantity of a second material over the first oxide, and    e) repeating the previous three steps b), c) and d) a number of times until a layered structure having a desired periodicity and a desired structure thickness is completed.    
   
   
       43 . The method of  claim 42  wherein each of the first non-porous electrochemically oxidizable material and second material comprises a material selected from the list consisting of Al, Ta, Nb, W, Bi, Sb, Ag, Cd, Fe, Mg, Si, Sn, Zn, Ti, Cu, Mo, Hf, Zr, Ti, V, Au, and Cr, and alloys, mixtures, and combinations thereof.  
   
   
       44 . The method of  claim 42 , wherein the first non-porous electrochemically oxidizable material and the second material comprise different materials.  
   
   
       45 . The method of  claim 42 , wherein the second material comprises a material that is not electrochemically oxidizable.  
   
   
       46 . The method of  claim 42 , wherein the second material comprises a metal selected from the list consisting of platinum, palladium, and rhodium.  
   
   
       47 . The method of  claim 42 , wherein the first non-porous electrochemically oxidizable material comprises aluminum.  
   
   
       48 . The method of  claim 42 , wherein the first non-porous electrochemically oxidizable material comprises tantalum.  
   
   
       49 . The method of  claim 42 , wherein the second material comprises aluminum.  
   
   
       50 . The method of  claim 42 , wherein the second material comprises tantalum.  
   
   
       51 . The method of  claim 42 , wherein the first non-porous electrochemically oxidizable material and the second material comprise the same material.  
   
   
       52 . The method of  claim 42 , further comprising the step of oxidizing the second material.  
   
   
       53 . The method of  claim 52 , further comprising the step of forming an edge on the second material before oxidizing the second material.  
   
   
       54 . The method of  claim 53 , wherein the step of oxidizing the second material is performed by anodizing its edge.  
   
   
       55 . The method of  claim 42 , wherein the periodic layered structure comprises a superlattice.  
   
   
       56 . The method of  claim 42 , wherein the first-layer thickness of the first electrochemically oxidizable layer is greater than or about equal to two nanometers (2 nm).  
   
   
       57 . The method of  claim 42 , wherein the periodicity is greater than or about equal to five nanometers (5 nm).  
   
   
       58 . The method of  claim 42 , wherein the substrate is substantially planar.  
   
   
       59 . The method of  claim 42 , wherein the steps are performed in the order recited.  
   
   
       60 . The method of  claim 42 , further comprising the step of planarizing the first electrochemically oxidizable layer.  
   
   
       61 . The method of  claim 42 , further comprising the step of planarizing the first oxide.  
   
   
       62 . The method of  claim 42 , further comprising the step of planarizing the second material.  
   
   
       63 . The periodic layered structure made by the method of  claim 42 .  
   
   
       64 . A method for fabricating a layered structure having physical and chemical properties varying periodically at least along a direction perpendicular to its layers, the method comprising the steps of: 
 a) providing a substrate,    b) depositing a quantity of a first non-porous electrochemically oxidizable material over the substrate to form a first layer having a first-layer thickness,    c) depositing a quantity of a second non-porous electrochemically oxidizable material over the first layer to form a second layer having a second-layer thickness,    d) anodizing both the first and second layers until a composite layer of first and second oxides is formed, and    e) repeating the previous three steps b), c) and d) a number of times until a periodic layered structure having a desired periodicity and a desired structure thickness is completed.    
   
   
       65 . The method of  claim 64  wherein each of the first and second non-porous electrochemically oxidizable materials comprises a material selected from the list consisting of Al, Ta, Nb, W, Bi, Sb, Ag, Cd, Fe, Mg, Si, Sn, Zn, Ti, Cu, Mo, Hf, Zr, Ti, V, Au, and Cr, and alloys, mixtures, and combinations thereof.  
   
   
       66 . The method of  claim 64 , wherein the first non-porous electrochemically oxidizable material and the second non-porous electrochemically oxidizable material comprise different materials.  
   
   
       67 . The method of  claim 64 , wherein the first non-porous electrochemically oxidizable material comprises aluminum.  
   
   
       68 . The method of  claim 64 , wherein the non-porous electrochemically oxidizable material comprises tantalum.  
   
   
       69 . The method of  claim 64 , wherein the second non-porous electrochemically oxidizable material comprises aluminum.  
   
   
       70 . The method of  claim 64 , wherein the second non-porous electrochemically oxidizable material comprises tantalum.  
   
   
       71 . The method of  claim 64 , wherein the first non-porous electrochemically oxidizable material and the second non-porous electrochemically oxidizable material comprise the same material.  
   
   
       72 . The method of  claim 64 , wherein step d) is performed by partially anodizing at least the second layer.  
   
   
       73 . The method of  claim 64 , wherein the periodic layered structure comprises a superlattice.  
   
   
       74 . The method of  claim 64 , wherein the first-layer thickness is greater than or about equal to two nanometers (2 nm).  
   
   
       75 . The method of  claim 64 , wherein the second-layer thickness is greater than or about equal to two nanometers (2 nm).  
   
   
       76 . The method of  claim 64 , wherein the periodicity is greater than or about equal to five nanometers (5 nm).  
   
   
       77 . The method of  claim 64 , wherein the substrate is substantially planar.  
   
   
       78 . The method of  claim 64 , wherein the steps are performed in the order recited.  
   
   
       79 . The method of  claim 64 , further comprising the step of planarizing the first layer.  
   
   
       80 . The method of  claim 64 , further comprising the step of planarizing the second layer.  
   
   
       81 . The periodic layered structure made by the method of  claim 64 .  
   
   
       82 . A method for fabricating an imprinting stamp for lithography, the method comprising the steps of: 
 a) providing a periodic layered structure having a periodicity, the periodic layered structure comprising layers of at least two materials differing in etch rate to a predetermined etchant, at least one of the layers being formed by electrochemical oxidation, the layers having edges of the at least two materials, and    b) selectively etching back the edge of at least one of the at least two materials with the predetermined etchant to form recesses separated by salient portions, thereby forming an imprinting stamp having the periodicity of the periodic layered structure.    
   
   
       83 . The imprinting stamp made by the method of  claim 82 .  
   
   
       84 . A method for fabricating an imprinting stamp for lithography, the method comprising the steps of: 
 a) providing a substrate,    b) depositing a quantity of non-porous electrochemically oxidizable material over the substrate to form a first layer having a first-layer thickness and a first-layer edge,    c) anodizing the non-porous electrochemically oxidizable material until a second-layer thickness of oxide is formed,    d) repeating alternately the steps b) of depositing and c) of anodizing until a periodic layered structure having a desired periodicity and a desired structure thickness is completed, and    e) selectively etching back one of the first-layer edge or the second-layer oxide of each layer to form a recess, whereby an imprinting stamp having the desired periodicity is formed.    
   
   
       85 . The imprinting stamp made by the method of  claim 84 .  
   
   
       86 . A method for fabricating an imprinting stamp for lithography, the method comprising the steps of: 
 a) providing a substrate,    b) depositing a quantity of a first non-porous electrochemically oxidizable material over the substrate to form a first layer having a first-layer thickness,    c) anodizing the first layer until a desired thickness of first oxide is formed,    d) depositing a quantity of a second material over the first oxide, whereby a second layer having a second-layer thickness is formed,    e) repeating the previous three steps b), c), and d) a number of times until a layered structure having a desired periodicity and a desired structure thickness is completed,    f) forming a second-layer edge of at least each second layer,    g) anodizing each second-layer edge until a desired thickness of second oxide is formed, and    h) selectively etching back one of the first oxide and second oxide, whereby an imprinting stamp having the desired periodicity is formed.    
   
   
       87 . The method of  claim 86 , wherein the first non-porous electrochemically oxidizable material and the second material comprise different materials.  
   
   
       88 . The method of  claim 86 , wherein the first non-porous electrochemically oxidizable material and the second material comprise different materials selected form the list consisting of Al, Ta, Nb, W, Bi, Sb, Ag, Cd, Fe, Mg, Si, Sn, Zn, Ti, Cu, Mo, Hf, Zr, Ti, V, Au, and Cr, and alloys, mixtures, and combinations thereof.  
   
   
       89 . The method of  claim 86 , wherein the first non-porous electrochemically oxidizable material is aluminum and the first oxide is aluminum oxide.  
   
   
       90 . The method of  claim 86 , wherein the second material is tantalum and the second oxide is tantalum oxide.  
   
   
       91 . The method of  claim 86 , wherein the periodic layered structure comprises a superlattice.  
   
   
       92 . The method of  claim 86 , wherein the first-layer thickness is greater than or about equal to two nanometers (2 nm).  
   
   
       93 . The method of  claim 86 , wherein the second-layer thickness is greater than or about equal to two nanometers (2 nm).  
   
   
       94 . The method of  claim 86 , wherein the periodicity is greater than or about equal to five nanometers (5 nm).  
   
   
       95 . The method of  claim 86 , wherein the substrate is substantially planar.  
   
   
       96 . The method of  claim 86 , wherein the steps are performed in the order recited.  
   
   
       97 . The method of  claim 86  further comprising the step of planarizing the first layer.  
   
   
       98 . The method of  claim 86  further comprising the step of planarizing the first oxide.  
   
   
       99 . The method of  claim 86 , further comprising the step of planarizing the second layer.  
   
   
       100 . The imprinting stamp made by the method of  claim 86.