Methods and apparatus of field-induced pressure imprint lithography

Abstract

An improved method of imprint lithography involves using fluid-induced pressure from electric or magnetic fields to press a mold onto a substrate having a moldable surface. In essence, the method comprises the steps of providing a substrate having a moldable surface, providing a mold having a molding surface and pressing the molding surface and the moldable surface together by electric or magnetic fields to imprint the molding surface onto the moldable surface. The molding surface advantageously comprises a plurality of projecting features of nanoscale extent or separation, but the molding surface can also be a smooth planar surface, as for planarization. The improved method can be practiced without mechanical presses and without sealing the region between the mold and the substrate.

What is claimed:  
     
         1 . A method for processing a moldable surface comprising the steps of: 
 providing a substrate having the moldable surface;    providing a mold having a molding surface;    pressing the molding surface and the moldable surface together by electric or magnetic field-induced pressure to imprint the molding surface onto the moldable surface; and    withdrawing the mold from the moldable surface.    
     
     
         2 . The method of  claim 1  wherein the moldable surface comprises one or more moldable layers disposed on the substrate.  
     
     
         3 . The method of  claim 2  wherein the imprinting produces reduced thickness regions in the moldable layer and further comprising the steps of: 
 removing the material of the moldable layer from the reduced thickness regions to selectively expose regions of the substrate; and  
 further processing the substrate selectively in the exposed regions.  
 
     
     
         4 . The method of  claim 3  wherein the further processing comprises doping the substrate with impurities, removing material from the substrate, or adding material on the substrate.  
     
     
         5 . The method of  claim 1  further comprising the step of hardening the moldable surface after pressing.  
     
     
         6 . The method of  claim 1  wherein the substrate or the mold or both are sufficiently flexible to conform together under the pressure.  
     
     
         7 . The method of  claim 2  where the thickness of the moldable layer is in the range 0.1 nm to 200 μm.  
     
     
         8 . Apparatus for imprinting a moldable surface on a substrate comprising: 
 a mold having a molding surface;    a substrate having a moldable surface positioned adjacent the molding surface of the mold;    a first chargeable or conductive layer disposed distal to the moldable surface/molding surface interface on the mold side of the interface;    a second chargeable or conductive layer disposed distal to the moldable surface/molding surface interface on the moldable surface side of the interface; and    means for forming an electrical field between the first and second layers to press the molding surface and the moldable surface together.    
     
     
         9 . The apparatus of  claim 8  wherein at least one of the first and second layers is conductive and the means for forming an electrical field comprises a voltage source.  
     
     
         10 . The apparatus of  claim 9  wherein the first and second layers comprise conductive material.  
     
     
         11 . The apparatus of  claim 9  wherein the voltage source comprises a DC voltage source.  
     
     
         12 . The apparatus of  claim 9  wherein the voltage source comprises an AC voltage source.  
     
     
         13 . The apparatus of  claim 9  wherein the voltage source comprises a pulsed voltage source.  
     
     
         14 . The apparatus of  claim 9  wherein the voltage source can provide a combination of DC, AC and pulsed voltage.  
     
     
         15 . The apparatus of  claim 9  wherein the mold includes a conductive layer.  
     
     
         16 . The apparatus of  claim 10  wherein the voltage source is connected between the layers of conductive material.  
     
     
         17 . The apparatus of  claim 9  wherein the mold and the substrate are disposed between at least two external electrodes and the means for forming an electrical field comprises a voltage source to apply a voltage between the external electrodes.  
     
     
         18 . The apparatus of  claim 17  wherein the voltage source is an AC or pulsed voltage source.  
     
     
         19 . Apparatus for imprinting a moldable surface on a substrate comprising: 
 a mold having a molding surface;    a substrate having a moldable surface positioned adjacent the molding surface;    a magnetic layer disposed distal to the moldable surface/molding surface interface;    and a magnetic field generator to generate a magnetic field interacting with the first magnetic layer to press the molding surface and the moldable surface together.    
     
     
         20 . The apparatus of  claim 19  wherein the magnetic layer comprises a conductive coil or spiral.  
     
     
         21 . The apparatus of  claim 19  wherein the magnetic field generator comprises a conductive coil or spiral.  
     
     
         22 . The apparatus of  claim 19  wherein the magnetic layer comprises a layer of magnetized material.  
     
     
         23 . The apparatus of  claim 19  wherein the magnetic layer comprises a layer of magnetizable material.  
     
     
         24 . The method of  claim 1  further comprising the step of applying imprint pressure mechanically or as direct fluid pressure.