Numerical simulation of surface-plasmon-assisted nanolithography.

In this paper, based on numerical study using Finite Difference Time Domain method, we discuss two possible illumination schemes utilizing surface plasmon effects to achieve high density sub-100 nm scale photolithography by using ultraviolet light from a mercury lamp. In the illumination schemes discussed in this paper, a thin film layer, named as shield layer, is placed in between a photoresist layer and a silicon substrate. In the first scheme, the shield material is titanium. Simulations show that the surface plasmons excited on both the metallic mask and the titanium shield enable the transfer of high density nanoscale pattern using mercury lamp emission. In the second scheme, a silicon dioxide layer is used instead of the titanium to avoid possible metal contamination. The two schemes discussed in this paper offer convenient, low cost, and massive pattern transfer methods by simple adjustment to the traditional photolithography method.