Methods and apparatus of field-induced pressure imprint lithography

Abstract

An improved method of imprint lithography involves using field-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 field-induced pressure from 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.

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 with protruding and recessed features to imprint a pattern;   pressing the molding surface and the moldable surface together by electric 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 with protruding and recessed features to imprint a pattern;   a substrate having a moldable surface positioned adjacent the molding surface of the mold; and   means for pressing the molding surface and the moldable surface together with a field-induced pressure without unbalanced lateral forces to imprint the molding surface onto the moldable surface.   
     
     
         9 . The apparatus of  claim 8  wherein the means for pressing comprises:
 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; 
 a voltage source for forming an electrical field between the first and second layers, said electric field imparting a field-induced pressure to press the molding surface and the moldable surface together; and 
 wherein at least one of the first and second layers is conductive. 
 
     
     
         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 voltage source is coupled to apply a voltage between the external electrodes. 
     
     
         18 . Apparatus in accordance with  claim 8  wherein the pressing means comprises:
 a magnetic layer disposed distal to the interface of the moldable surface and the moldable 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. 
 
     
     
         19 . The apparatus of  claim 18  wherein the magnetic layer comprises a conductive coil or spiral. 
     
     
         20 . The apparatus of  claim 18  wherein the magnetic field generator comprises a conductive coil or spiral. 
     
     
         21 . The apparatus of  claim 18  wherein the magnetic layer comprises a layer of magnetized material. 
     
     
         22 . The apparatus of  claim 18  wherein the magnetic layer comprises a layer of magnetizable material. 
     
     
         23 . The apparatus of  claim 8  wherein the molding surface has at least two projecting features spaced apart by less than 200 nanometers. 
     
     
         24 . The method of  claim 1  wherein providing a mold comprises providing a mold having a molding surface having at least two projecting features spaced apart by less than 200 nanometers. 
     
     
         25 . A method for imprinting a moldable surface with a pattern having nanoscale features without unwanted lateral shifts in the imprinting comprising the steps of:
 providing the moldable surface;   providing a mold having a molding surface with protruding and recessed features to imprint a pattern having nanoscale features; and   pressing the molding surface and the moldable surface together by electric-field induced pressure to imprint the molding surface onto the moldable surface.   
     
     
         26 . A method for imprinting a moldable surface with a pattern having nanoscale features without unwanted lateral shifts in the imprinting comprising the steps of:
 providing the moldable surface;   providing a mold having a molding surface with protruding and recessed features to imprint a pattern having nanoscale features; and   pressing the molding surface and the moldable surface together by magnetic-field induced pressure to imprint the molding surface onto the moldable surface.