Direct Imprinted Conductive Patterns using Nanosilver Colloid-Applied UV Curable Resist

Abstract

In conventional nanoimprinting using acrylate-based resists, the imprinted resist acts as a sacrificial barrier for the underlayer etch. However, the imprinted patterns can be directly used for electronic device structures immediately after removal of the residual layers if electrically conductive functional resists are used. In this work, we used a UV-curable monomer, hydroxyethyl methacrylate mixed with a highly concentrated nanosilver colloid, for direct imprinting. The imprinted patterns were heat-treated to cause sintering of the nanosilver particles, and to shrink the cured polymer matrix. Then silver etchant was applied to remove the residual layer before a thorough rinsing. Pattern shrinkage was investigated at each process stage as a function of nanosilver concentration. Shrinkage depended slightly on pattern width, and had a strong correlation with Ag loading in the range of 40–60 wt %. The electrical resistivity was estimated at 40.8 nΩ·m, which is quite close to that of bulk silver, 15.87 nΩ·m.