Method and Apparatus of Forming Cracks as Masks for the Fabrication of Micro-Metal Mesh

Abstract

Methods and systems for forming cracks as masks for the fabrication of micro-metal mesh are disclosed, including depositing a composite film onto a substrate wherein the composite film comprises a brittle layer, a brittle layer atop a mediate layer, or a brittle layer atop a sacrificial layer; generating a tensile stress in the substrate and/or the composite film in order to form micro-cracks in the brittle layer; tuning widths of the micro-cracks; transferring pattern of the micro-cracks onto the sacrificial layer; depositing a conductive material onto the brittle layer and the area of the substrate or mediate layer exposed by the pattern of the micro-cracks; and performing a lift-off of the brittle layer and if present the sacrificial layer from the substrate or mediate layer, resulting in the micro-metal mesh atop the substrate or mediate layer. Other embodiments are described and claimed.

1 . A method for fabricating a micro-metal mesh, the method comprising:
 depositing a mediate layer onto a substrate;   depositing a brittle layer onto the mediate layer;   generating a tensile stress in the substrate, the mediate layer, and/or the brittle layer in order to form micro-cracks in the brittle layer;   tuning widths of the micro-cracks;   depositing a conductive material onto the brittle layer and the area of the mediate layer exposed by the pattern of the micro-cracks; and   performing a lift-off of the brittle layer from the mediate layer, resulting in the micro-metal mesh atop the mediate layer.   
     
     
         2 . The method of  claim 1 , wherein tuning the widths of the micro-cracks comprises etching the brittle layer or annealing the substrate, the mediate layer, and the brittle layer. 
     
     
         3 . The method of  claim 2 , wherein the annealing comprises a temperature ranging from about 40° C. to about 180° C. 
     
     
         4 . The method of  claim 2 , wherein the annealing comprises a time ranging from about 10 seconds to about 1 hour. 
     
     
         5 . The method of  claim 1 , wherein the substrate comprises a transparent and flexible film having a material selected from the group consisting of polyethylene terephthalate, polyimide, cellulose, polyester, polyethylene, polyolefin, polycarbonate, glass, or a combination or lamination thereof. 
     
     
         6 . The method of  claim 1 , wherein the brittle layer comprises spin-on-glass, liquid glass, ceramic, salt, carbon, and/or PMMA. 
     
     
         7 . The method of  claim 1 , wherein the mediate layer comprises a material selected from the group consisting of PMMA, PS, PVC, rubber, silicone, PDMS, nylon, or a combination thereof. 
     
     
         8 . The method of  claim 1 , wherein the conductive material comprises a metal, alloy, and/or doped semiconductor having a material selected from the group consisting of silver, copper, gold, iron, nickel, cobalt, platinum, palladium, titanium, aluminum, chromium, molybdenum, or a combination thereof. 
     
     
         9 . The method of  claim 1 , wherein the micro-cracks comprise a width ranging from about 20 nm to about 5 μm. 
     
     
         10 . The method of  claim 1 , wherein generating a tensile stress comprises mechanical bending, stretching, squeezing, pressing, thermal shock, quenching, and/or adding nanoparticles in the brittle layer. 
     
     
         11 . The method of  claim 10 , wherein the nanoparticles comprise silver, copper, gold, iron, nickel, cobalt, platinum, palladium, titanium, aluminum, chromium, and/or molybdenum. 
     
     
         12 . The method of  claim 1 , wherein the method is roll-to-roll compatible. 
     
     
         13 . A method for fabricating a micro-metal mesh, the method comprising:
 depositing a sacrificial layer onto a substrate;   depositing a brittle layer onto the sacrificial layer;   generating a tensile stress in the substrate, the sacrificial layer, and/or the brittle layer in order to form micro-cracks in the brittle layer;   tuning widths of the micro-cracks;   transferring pattern of the micro-cracks onto the sacrificial layer;   depositing a conductive material onto the brittle layer and the area of the substrate exposed by the pattern of the micro-cracks transferred onto the sacrificial layer; and   performing a lift-off of the sacrificial layer and the brittle layer from the substrate, resulting in the micro-metal mesh atop the substrate.   
     
     
         14 . The method of  claim 13 , wherein tuning the widths of the micro-cracks comprises etching the brittle layer or annealing the substrate, the sacrificial layer, and the brittle layer. 
     
     
         15 . The method of  claim 14 , wherein the annealing comprises a temperature ranging from about 40° C. to about 180° C. 
     
     
         16 . The method of  claim 14 , wherein the annealing comprises a time ranging from about 10 seconds to about 1 hour. 
     
     
         17 . The method of  claim 13 , wherein transferring the pattern of the micro-cracks onto the sacrificial layer comprises dissolving and/or reaction ion etching the sacrificial layer exposed by the pattern of the micro-cracks in the brittle layer. 
     
     
         18 . The method of  claim 13 , wherein the substrate comprises a transparent and flexible film having a material selected from the group consisting of polyethylene terephthalate, polyimide, cellulose, polyester, polyethylene, polyolefin, polycarbonate, glass, or a combination or lamination thereof. 
     
     
         19 . The method of  claim 13 , wherein the brittle layer comprises spin-on-glass, liquid glass, ceramic, salt, carbon, and/or PMMA. 
     
     
         20 . The method of  claim 13 , wherein the sacrificial layer comprises a polymer selected from the group consisting of PMMA, PS, PVC, rubber, silicone, PDMS, nylon, and photo resist. 
     
     
         21 . The method of  claim 13 , wherein the conductive material comprises a metal, alloy, and/or doped semiconductor having a material selected from the group consisting of silver, copper, gold, iron, nickel, cobalt, platinum, palladium, titanium, aluminum, chromium, molybdenum, or a combination thereof. 
     
     
         22 . The method of  claim 13 , wherein the micro-cracks comprise a width ranging from about 20 nm to about 5 μm. 
     
     
         23 . The method of  claim 13 , wherein generating a tensile stress comprises mechanical bending, stretching, squeezing, pressing, thermal shock, quenching, and/or adding nanoparticles in the brittle layer. 
     
     
         24 . The method of  claim 23 , wherein the nanoparticles comprise silver, copper, gold, iron, nickel, cobalt, platinum, palladium, titanium, aluminum, chromium, and/or molybdenum. 
     
     
         25 . The method of  claim 13 , wherein the method is roll-to-roll compatible. 
     
     
         26 . An apparatus for forming micro-cracks in a brittle layer, the apparatus comprising:
 a roller having a diameter;   the apparatus configured to:
 drive a composite film around the roller to generate a tensile stress in the composite film, wherein the composite film comprises the brittle layer atop a substrate; and 
 form cracks in the brittle layer, wherein the cracks are parallel to the axis of the roller and have a period dependent on the diameter of the roller. 
   
     
     
         27 . The apparatus of  claim 26 , wherein the composite film further comprises a mediate layer or a sacrificial layer between the brittle layer and the substrate. 
     
     
         28 . The apparatus of  claim 26 , wherein the roller the diameter ranges from about 1.6 mm to about 30 mm.