Deposited thin film void-column network materials

Abstract

A novel porous film is disclosed comprising a network of silicon columns in a continuous void which may be fabricated using high density plasma deposition at low temperatures, i.e., less than about 250 ° C. This silicon film is a two-dimensional nano-sized array of rodlike columns. This void-column morphology can be controlled with deposition conditions and the porosity can be varied up to 90%. The simultaneous use of low temperature deposition and etching in the plasma approach utilized, allows for the unique opportunity of obtaining columnar structure, a continuous void, and polycrystalline column composition at the same time. Unique devices may be fabricated using this porous continuous film by plasma deposition of this film on a glass, metal foil, insulator or plastic substrates.

What is claimed is:  
     
         1 . A porous film comprising a plurality of perturbations extending therefrom into a void having a porosity of up to about 90%.  
     
     
         2 . The porous film of  claim 1 , wherein the plurality of perturbations are disposed substantially perpendicular to a substrate.  
     
     
         3 . The porous film of  claim 1 , wherein the plurality of perturbations are disposed substantially perpendicular to a base layer.  
     
     
         4 . The porous film of  claim 1 , wherein the plurality of perturbations are rod-like shaped columns.  
     
     
         5 . The porous film of  claim 1 , wherein said perturbations are semiconducting.  
     
     
         6 . The porous film of  claim 1 , wherein said perturbations are polycrystalline or amorphous.  
     
     
         7 . The porous film of  claim 6 , wherein said polycrystalline or amorphous phase is a silicon material.  
     
     
         8 . The porous film of  claim 1 , wherein said film is of a thickness greater than about 10 nm.  
     
     
         9 . The porous film of  claim 1 , wherein said perturbations have a diameter from about 1 nm to about 50 nm.  
     
     
         10 . The porous film of  claim 9 , wherein said perturbations have a diameter from about 3 nm to 7 nm.  
     
     
         11 . The porous film of  claim 1 , wherein said perturbations are found in clusters having a diameter between about 50 to 500 nm.  
     
     
         12 . The porous film of  claim 1 , wherein porosity of the porous film is controllable by at least one of the following: substrate coating, plasma power, process pressure, magnetic field, plasma-substrate bias, chamber conditioning, deposition gases, flow rates, and deposition temperature.  
     
     
         13 . A composite structure which comprises: 
 a substrate; and    a porous film comprising a plurality of perturbations extending therefrom into a void having a porosity of up to 90%,    wherein said porous film is disposed on said substrate.    
     
     
         14 . The composite structure of  claim 13 , further comprising a substrate coating layer such that said porous film is disposed on said substrate coating layer.  
     
     
         15 . The composite structure of  claim 14 , wherein said substrate coating layer is at least one coating material selected from the group consisting of: organic insulators, silicon nitride, and silicon oxide.  
     
     
         16 . The composite structure of  claim 14 , wherein said coating layer is at least one active material selected from the group consisting of: piezoelectrics, ferroelectrics, metals, and semiconductors.  
     
     
         17 . The composite structure of  claim 13 , further comprising a capping layer, such that said porous film is disposed between said capping layer and said substrate.  
     
     
         18 . The composite structure of  claim 17 , wherein said capping layer is at least one insulation material selected from the group consisting of: organic insulators, silicon nitride, and silicon oxide.  
     
     
         19 . The composite structure of  claim 17 , wherein said capping layer is at least one active material selected from the group consisting of: piezoelectrics, ferroelectrics, metals, and semiconductors.  
     
     
         20 . The composite structure of  claim 13 , wherein said porous film has a thickness greater than about 10 nm.  
     
     
         21 . The composite structure of  claim 13 , wherein said porous film is polycrystalline or amorphous.  
     
     
         22 . The composite structure of  claim 21 , wherein the polycrystalline or amorphous porous film is structured in a two-dimensional periodic array of rod-like perturbations.  
     
     
         23 . The composite structure of  claim 22 , wherein said rodlike perturbations have a diameter of between about 1 to 50 nm.  
     
     
         24 . The composite structure of  claim 22 , wherein said rodlike perturbations are found in clusters with a diameter between about 50 to 500 nm.  
     
     
         25 . The composite structure of  claim 13 , wherein said substrate is selected from the group consisting of: glass, metal foil, insulation material, plastic material, and semiconductor-containing material.  
     
     
         26 . A method of forming a composite structure comprising a substrate and a porous film, said method comprising the step of depositing said porous film on a substrate via high density plasma deposition at a temperature of less than 250° C.  
     
     
         27 . A method of  claim 26 , wherein said porous film comprises a plurality of perturbations extending therefrom into a void having a porosity of up to about 90%.  
     
     
         28 . A method of  claim 26 , further comprising the step of etching said porous film.  
     
     
         29 . A method of  claim 28 , wherein said deposition and etching steps occur simultaneously.  
     
     
         30 . A method of  claim 28 , wherein said etching is conducted by hydrogen, chlorine, fluorine, HCl, HF and their derivative radicals.  
     
     
         31 . A method of  claim 26 , wherein said high density plasma deposition is conducted in the presence of a precursor environment comprising silicon-containing gas.  
     
     
         32 . The method of  claim 31 , wherein said precursor environment comprises at least one gas selected from the group consisting of: hydrogen and silicon-containing gas.  
     
     
         33 . The method of  claim 32 , wherein said silicon-containing gas is silane.  
     
     
         34 . The method of  claim 26 , wherein said deposition step is conducted in the presence of a magnetic field in the vicinity of the substrate in the range between about +800 to −600 Gauss.  
     
     
         35 . The method of  claim 26 , wherein said deposition step is conducted in the presence of a microwave excitation frequency in the range between about 100 Watts to 1200 Watts.  
     
     
         36 . The method of  claim 26 , wherein said deposition step is conducted with no impressed voltage between the plasma and substrate.  
     
     
         37 . The method of  claim 26 , wherein said composite structure further comprises a substrate coating layer, such that said porous film is disposed on said substrate coating layer.  
     
     
         38 . The composite structure of  claim 37 , wherein said substrate coating layer is at least one coating material selected from the group consisting of: organic insulators, silicon nitride, and silicon oxide.  
     
     
         39 . The method of  claim 37 , wherein said coating layer is at least one active material selected from the group consisting of: piezoelectrics, ferroelectrics, metals, and semiconductors.  
     
     
         40 . The method of  claim 26 , wherein said composite structure further comprises a capping layer, such that said porous film is disposed between said capping layer and said substrate.  
     
     
         41 . The method of  claim 40 , wherein said capping layer is at least one insulation material selected from the group consisting of: organic insulators, silicon nitride, and silicon oxide.  
     
     
         42 . The method of  claim 40 , wherein said capping layer is at least one active material selected from the group consisting of: piezoelectrics, ferroelectrics, metals, and semiconductors.  
     
     
         43 . The method of  claim 26 , wherein porosity is controllable by at least one of the following: substrate coating, plasma power, process pressure, magnetic field, plasma-substrate bias, chamber conditioning, deposition gases, flow rates, and deposition temperature.  
     
     
         44 . The method of  claim 26 , wherein at least a portion of the porous layer in said porous film is removed by etching thereby creating an airgap, release, or isolation structure.  
     
     
         45 . A sensor which comprises a composite structure having: 
 a substrate; and    a porous film comprising a plurality of perturbations extending therefrom into a void having a porosity of up to 90%, wherein said porous film is disposed on said substrate.    
     
     
         46 . The sensor of  claim 45 , wherein said sensor is capable of monitoring lateral resistivity, optical, or dielectric response.  
     
     
         47 . A gas detector which comprises a composite structure having: 
 a substrate; and    a porous film comprising a plurality of perturbations extending therefrom into a void having a porosity of up to 90%, wherein said porous film is disposed on said substrate.    
     
     
         48 . An analytical device which comprises a composite structure having: 
 a substrate; and    a porous film comprising a plurality of perturbations extending therefrom into a void having a porosity of up to 90%, wherein said porous film is disposed on said substrate.    
     
     
         49 . The analytical device of  claim 48 , wherein said device is capable of desorption mass spectroscopy.