Theoretical Analysis of Interference Nanolithography of Surface Plasmon Polaritons without a Match Layer

Interference nanolithography techniques based on long-range surface plasmon polaritons (LR-SPP) are hardly ever achieved by experiments at present. One key reason is that suitable liquid materials are difficult to find as the match layer connects the metal film and the resist. We redesign a Kretschmann-Raether structure for interference lithography. A polymer layer is coated under the metal film, and an air layer is placed between the polymer layer and the resist layer. This design not only avoids the above-mentioned question of the match layer, but also can form a soft contact between the polymer layer and the resist layer and can protect the exposure pattern. Simulation results confirm that a device with an appropriately thick polymer layer can form high intensity and contrast interference fringes with a critical dimension of about λ/7 in the resist. In addition, the fabrication of the device is very easy.