Sub-diffraction optical beam lithography based on a center-non-zero depletion laser

Abstract

Photoinhibition (PI) mechanisms have been introduced in nanofabrication which allows breaking the diffraction limit by large factors. Donut-shaped laser is usually selected as a depletion beam to reduce linewidth, but the parasitic process has made the results of the experiment less than expected. As a result, the linewidth is difficult to achieve below 50 nm with 780 nm femtosecond and 532 nm continuous-wave lasers. Here, we propose a new, to the best of our knowledge, method based on a center-non-zero (CNZ) depletion laser to further reduce linewidth. By constructing a smaller zone of action under the condition of keeping the maximum depletion intensity constant, a minimum linewidth of 30 nm (λ / 26) was achieved. Two ways to construct CNZ spots were discussed and experimented, and the results show the advantages of our method to reduce the parasitic process to further improve the writing resolution.