Subdiffraction plasmonic lens lithography prototype in stepper mode

Abstract

In this paper, the authors present a low-cost and high-resolution lithography prototype by utilizing surface plasmons. In the surface plasmon lithography (SPL) prototype, a metal-photoresist-metal plasmonic cavity lens is adopted to amplify evanescent waves, thereby addressing the issues of poor fidelity, low contrast, and short working distance suffered from the conventional near-field optical lithography. The authors achieved the photoresist patterns with high resolution, high contrast, and high exposure depth experimentally by using an Hg lamp with 365 nm wavelength. Hole array patterns with radius of 50 nm and period of 160 nm were realized. Moreover, the grating array patterns with line width of 32(60) nm and period of 64(120) nm were successfully achieved. Furthermore, the authors introduced a step exposure method to fabricate a 5 × 5 array of grating patterns with a step length of 300 μm and the uniform patterns cover the whole area of about 2 × 2 mm2. Step exposure is valuable, which makes SPL have the ability to obtain a large-area pattern exposure, especially in the condition that the mask area is far smaller than the exposure region. It is believed that this prototype provides a low-cost, high-throughput, and high-resolution nanofabrication route for fabricating nanostructure devices.