Custom electrodes for molecular memory and logic devices

Abstract

A method for tailoring at least portions of an exposed non-planar layered surface of a conductive layer formed on a substrate having a first surface roughness to provide the exposed surface with a second surface roughness. The method includes: forming the conductive layer on the substrate; and tailoring at least portions of the exposed surface of the conductive layer in a plasma to at least smooth the exposed surface of the conductive layer, whereby the second surface roughness is essentially the same as the first surface roughness.

1 . A method for tailoring at least portions of an exposed non-planar layered surface of a layer of conductive material formed on a substrate having a first surface roughness to provide said exposed surface with a second surface roughness, said method including: 
 forming said conductive layer on said substrate; and    tailoring at least portions of said exposed surface of said conductive layer in a plasma to at least smooth said exposed surface of said conductive layer, whereby said second surface roughness is essentially the same as said first surface roughness.    
   
   
       2 . The method of  claim 1  wherein said tailoring is performed in a plasma to additionally accomplish at least one of the following: (a) rearrange said conductive layer, (b) alter the hydrophilicity of said exposed layer, and (c) provide a barrier layer due to the presence of an oxide film on said exposed surface.  
   
   
       3 . The method of  claim 2  wherein said plasma is selected from the group consisting of oxygen alone to provide a hydrophilic surface, oxygen and subsequent argon to provide a less hydrophilic, more hydrophobic surface, argon alone to provide a hydrophobic surface, or a sequence of oxygen and hydrogen to provide a smooth surface with reduced oxygen, which is passivated.  
   
   
       4 . The method of  claim 3  wherein said plasma contains oxygen, leaving an oxide film on said conductive layer, and wherein said oxide film is subsequently removed, leaving said smooth exposed surface of said conductive layer.  
   
   
       5 . The method of  claim 1  wherein said tailoring includes at least one of the following steps: cleaning and oxidizing to a predetermined level.  
   
   
       6 . The method of  claim 1  wherein said tailoring includes at least one of the following steps: actively smoothing, actively oxidizing, actively removing said oxide without re-roughening, and actively passivating.  
   
   
       7 . The method of  claim 1  wherein said conductive material comprises a material selected from Rows 1 B-7B and 8 of the Periodic Table.  
   
   
       8 . The method of  claim 7  wherein said conductive material is selected from the group consisting of platinum, tungsten, silver, aluminum, palladium, copper, nickel, chromium, molybdenum, titanium, and tantalum.  
   
   
       9 . The method of  claim 8  wherein said conductive material consists essentially of platinum.  
   
   
       10 . The method of  claim 1  wherein said second surface roughness is less than 8 Å RMS.  
   
   
       11 . The method of  claim 10  wherein said conductive layer has a thickness and wherein said second surface roughness is less than 0.8% of said thickness of said conductive layer.  
   
   
       12 . The method of  claim 10  wherein said second surface roughness is approximately 4 A Å RMS.  
   
   
       13 . The method of  claim 12  wherein said conductive layer has a thickness and wherein said second surface roughness is approximately 0.4% of said thickness of said conductive layer.  
   
   
       14 . A method of reliably fabricating a molecular electronic device comprising at least a first electrode and a molecular switch film thereon, said method comprising: 
 providing a substrate;    forming said first electrode on said substrate, said first electrode comprising a non-planar surface of tailored conductive material, said non-planar surface comprising either a layer or a nanowire; and    forming said molecular film on at least said first electrode, wherein said first electrode is formed by a process including:    cleaning portions of said substrate where said first electrode is to be deposited;    pre-sputtering said portions where said non-planar surface comprises said layer; and    forming said conductive layer having said non-planar surface on at least said portions.    
   
   
       15 . The method of  claim 14  wherein said non-planar surface comprises said layer.  
   
   
       16 . The method of  claim 15  wherein said substrate is provided with a coating on which said first electrode is deposited.  
   
   
       17 . The method of  claim 16  wherein said coating is subjected to said cleaning step and said pre-sputtering step before depositing said conductive layer.  
   
   
       18 . The method of  claim 15  wherein cleaning is performed with an oxygen plasma to remove organic contaminants.  
   
   
       19 . The method of  claim 15  wherein said pre-sputtering is performed under conditions to further clean said surface and remove environmental contaminants.  
   
   
       20 . The method of  claim 15  wherein said conductive layer is formed to a thickness of 50 to 5,000 Å.  
   
   
       21 . The method of  claim 15  wherein a resist is formed on a coating on said substrate and patterned, said pattern comprising an array of said first electrodes, wherein said patterning is done by removing resist from those areas where said conductive layer is to be deposited to form said first electrodes.  
   
   
       22 . The method of  claim 21  wherein said first electrode is formed by imprinting or molding.  
   
   
       23 . The method of  claim 21  wherein: 
 said exposed areas are cleaned with an oxygen plasma to remove organic contaminants;    said exposed areas are pre-sputtered to further clean said surface and remove environmental contaminants;    said conductive layer is blanket-deposited everywhere, to deposit a layer about 50 to 5,000 Å thick; and    said conductive layer is patterned to form said first electrodes.    
   
   
       24 . The method of  claim 14  wherein said non-planar surface comprises said nanowire.  
   
   
       25 . The method of  claim 24  wherein said substrate is provided with a coating on which said first electrode is formed.  
   
   
       26 . The method of  claim 24  wherein cleaning is performed with an oxygen plasma to remove organic contaminants.  
   
   
       27 . The method of  claim 24  wherein said conductive layer is formed to a diameter of 50 to 5,000 Å.  
   
   
       28 . The method of  claim 24  wherein a resist is formed on a coating on said substrate and patterned, said pattern comprising growth initiation sites for an array of said first electrodes, wherein said patterning is done by removing resist from those areas where said conductive layer is to be deposited to form said first electrodes.  
   
   
       29 . The method of  claim 28  wherein said first electrode is formed by imprinting or molding.  
   
   
       30 . The method of  claim 14  further including tailoring properties of the exposed surface of said conductive layer following its deposition.  
   
   
       31 . The method of  claim 30  wherein said tailoring is performed in a plasma to accomplish at least one of the following: (a) rearrange said conductive layer, (b) smooth said exposed surface of said conductive layer, (c) alter the hydrophilicity of said exposed layer, and (d) provide a barrier layer due to the presence of an oxide film on said exposed surface.  
   
   
       32 . The method of  claim 31  wherein said plasma is selected from the group consisting of oxygen alone to provide a hydrophilic surface, oxygen and subsequent argon to provide a less hydrophilic, more hydrophobic surface, argon alone to provide a hydrophobic surface, or a sequence of oxygen and hydrogen to provide a smooth surface with reduced oxygen, which is passivated.  
   
   
       33 . The method of  claim 32  wherein said plasma contains oxygen, leaving an oxide film on said conductive layer, and wherein said oxide film is subsequently removed, leaving said smooth exposed surface of said conductive layer.  
   
   
       34 . The method of  claim 30  wherein said tailoring includes at least one of the following steps: cleaning and oxidizing to a predetermined level.  
   
   
       35 . The method of  claim 30  wherein said tailoring includes at least one of the following steps: actively smoothing, actively oxidizing, actively removing said oxide without re-roughening, and actively passivating.  
   
   
       36 . The method of  claim 14  wherein said molecular device comprises an electrical element formed with two or more electrodes.  
   
   
       37 . The method of  claim 36  wherein said molecular device is selected from the group consisting of switches, diodes, resistors, transducers, and transistors.  
   
   
       38 . The method of  claim 37  further including forming a second contact on said molecule film and over said first layer to form a switch.  
   
   
       39 . The method of  claim 38  wherein said second contact is selected from the group consisting of second electrodes, circular electrodes, tip addressing, and a nanopore over said molecular film covered with an electrode.  
   
   
       40 . The method of  claim 14  wherein said conductive material comprises a material selected from Rows 1B-7B and 8 of the Periodic Table.  
   
   
       41 . The method of  claim 40  wherein said conductive material is selected from the group consisting of platinum, tungsten, silver, aluminum, palladium, copper, nickel, chromium, molybdenum, titanium, and tantalum.  
   
   
       42 . The method of  claim 41  wherein said conductive material consists essentially of platinum.  
   
   
       43 . A method of forming a nano-imprinted or molded layer of conductive material on a substrate having a first surface roughness, said conductive layer having a second surface roughness, where said second surface roughness is approximately the same as said first surface roughness, said method comprising: 
 cleaning portions of said substrate where said first electrode is to be deposited;    pre-sputtering said portions; and    depositing said conductive layer on at least said portions.    
   
   
       44 . The method of  claim 43 , wherein said conductive layer is deposited on at least said portions without formation of any sticking layer prior to depositing said conductive layer.  
   
   
       45 . The method of  claim 43  wherein cleaning is performed with an oxygen plasma to remove organic contaminants.  
   
   
       46 . The method of  claim 43  wherein said pre-sputtering is performed under conditions to further clean said surface and remove environmental contaminants.  
   
   
       47 . The method of  claim 43  wherein said depositing of said conductive layer is performed to a thickness of 50 to 5,000 Å.  
   
   
       48 . The method of  claim 43  further including tailoring properties of the exposed surface of said conductive layer following its deposition.  
   
   
       49 . The method of  claim 48  wherein said tailoring is performed in a plasma to accomplish at least one of the following: (a) rearrange said conductive layer, (b) smooth said exposed surface of said conductive layer, (c) alter the hydrophilicity of said exposed layer, and (d) provide a barrier layer due to the presence of an oxide film on said exposed surface.  
   
   
       50 . The method of  claim 49  wherein said plasma is selected from the group consisting of oxygen alone to provide a hydrophilic surface, oxygen and subsequent argon to provide a less hydrophilic, more hydrophobic surface, argon alone to provide a hydrophobic surface, or a sequence of oxygen and hydrogen to provide a smooth surface with reduced oxygen, which is passivated.  
   
   
       51 . The method of  claim 50  wherein said plasma contains oxygen, leaving an oxide film on said conductive layer, and wherein said oxide film is subsequently removed, leaving said smooth exposed surface of said conductive layer.  
   
   
       52 . The method of  claim 48  wherein said tailoring includes at least one of the following steps: cleaning and oxidizing to a predetermined level.  
   
   
       53 . The method of  claim 48  wherein said tailoring includes at least one of the following steps: actively smoothing, actively oxidizing, actively removing said oxide without re-roughening, and actively passivating.  
   
   
       54 . The method of  claim 43  wherein said conductive material comprises a material selected from Rows 1B-7B and 8 of the Periodic Table.  
   
   
       55 . The method of  claim 54  wherein said conductive material is selected from the group consisting of platinum, tungsten, silver, aluminum, palladium, copper, nickel, chromium, molybdenum, titanium, and tantalum.  
   
   
       56 . The method of  claim 55  wherein said conductive material consists essentially of platinum.  
   
   
       57 . The method of  claim 43  wherein said conductive layer has a thickness and wherein said second surface roughness is less than 0.8% of said thickness of said conductive layer.  
   
   
       58 . The method of  claim 57  wherein said conductive layer has a thickness and wherein said second surface roughness is approximately 0.4% of said thickness of said conductive layer.  
   
   
       59 . A method of tailoring the surface of a nanowire conductive layer on a substrate having a first surface roughness, said conductive layer having a second surface roughness, where said second surface roughness is approximately the same as said first surface roughness, said method comprising: 
 cleaning portions of said substrate where said nanowire is to be formed;    forming said nanowire on said substrate; and    performing said tailoring in a plasma to accomplish at least one of the following: (a) rearrange said conductive layer, (b) smooth said exposed surface of said conductive layer, (c) alter the hydrophilicity of said exposed layer, and (d) provide a barrier layer due to the presence of an oxide film on said exposed surface.    
   
   
       60 . The method of  claim 59  wherein said plasma is selected from the group consisting of oxygen alone to provide a hydrophilic surface, oxygen and subsequent argon to provide a less hydrophilic, more hydrophobic surface, argon alone to provide a hydrophobic surface, or a sequence of oxygen and hydrogen to provide a smooth surface with reduced oxygen, which is passivated.  
   
   
       61 . The method of  claim 60  wherein said plasma contains oxygen, leaving an oxide film on said conductive layer, and wherein said oxide film is subsequently removed, leaving said smooth exposed surface of said conductive layer.  
   
   
       62 . The method of  claim 59  wherein said tailoring includes at least one of the following steps: cleaning and oxidizing to a predetermined level.  
   
   
       63 . The method of  claim 59  wherein said tailoring includes at least one of the following steps: actively smoothing, actively oxidizing, actively removing said oxide without re-roughening, and actively passivating.  
   
   
       64 . The method of  claim 59  wherein said conductive material is selected from the group consisting of platinum, tungsten, silver, aluminum, palladium, copper, nickel, chromium, molybdenum, titanium, and tantalum.  
   
   
       65 . The method of  claim 64  wherein said conductive material consists essentially of platinum.