Articles Comprising Nanoscale Patterns With Reduced Edge Roughness and Methods of Making Same

Abstract

In accordance with the invention, an article comprising a nanoscale surface pattern, such as a grating, is provided with a nanoscale patterns of reduced edge and/or sidewall roughness. Smooth featured articles, can be fabricated by nanoimprint lithography using a mold having sloped profile molding features. Another approach uses a mold especially fabricated to provide smooth sidewalls of reduced roughness, and a third approach adds a post-imprint smoothing step. These approaches can be utilized individually or in various combinations to make the novel articles.

1 . A method of making an article comprising a nanoscale surface pattern having reduced edge and/or sidewall roughness comprising the steps of:
 providing a mold with a molding surface having one or more nanoscale protruding regions having smooth sidewalls with a surface roughness less than about 5 nanometers, the protruding regions arranged complementary to the pattern;   providing a work piece with a moldable surface;   pressing together the molding surface and moldable surface to reduce the thickness of the moldable surface under the protruding features; and   separating the mold from the moldable surface.   
     
     
         2 . The method of  claim 1  wherein providing the mold comprises the steps of:
 providing a mold substrate of (110) crystalline material with a nanoscale pattern of etch resistant material;   anisotropically etching the masked mold substrate with a wet etchant having an etching rate in the (111) crystal plane slower than the etching rate in the (100) and (110) planes to etch smooth sidewalls.   
     
     
         3 . The method of  claim 2  wherein the article comprises a mold for imprinting a nanoscale surface pattern. 
     
     
         4 . A method of masking an article comprising a nanoscale surface pattern having reduced edge and/or sidewall roughness comprising the steps of:
 providing a mold with a molding surface having one or more protruding regions arranged complementary to the pattern;   providing a work piece with a moldable surface of material having a glass transition temperature;   pressing together the molding surface and the moldable surface to reduce the thickness of the moldable surface under the protruding features, thereby imprinting the pattern on the moldable surface;   separating the mold from the moldable surface; and   heating the moldable surface above the glass transition temperature to smooth the edges and sidewalls of the imprinted pattern.   
     
     
         5 . The method of  claim 4  wherein the article comprises a mold for imprinting a nanoscale surface pattern.