Reconfigurable phase-change photomask for grayscale photolithography

• Main Authors: Wang, Q., Yuan, Guanghui, Kiang, K. S., Sun, K., Gholipour, B., Rogers, E. T. F., Huang, K., Ang, S. S., Zheludev, Nikolay I., Teng, J. H.
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2019
• Subjects: Semiconductors; Femtosecond Lasers; DRNTU::Science::Physics
• Online Access: https://hdl.handle.net/10356/81274; http://hdl.handle.net/10220/47486
• Institution: Nanyang Technological University

We demonstrate a grayscale photolithography technique which uses a thin phase-change film as a photomask to locally control the exposure dose and allows three-dimensional (3D) sculpting photoresist for the manufacture of 3D structures. Unlike traditional photomasks, the transmission of the phase-change material photomask can be set to an arbitrary gray level with submicron lateral resolution, and the mask pattern can be optically reconfigured on demand, by inducing a refractive-index-changing phase-transition with femtosecond laser pulses. We show a spiral phase plate and a phase-type super-oscillatory lens fabricated on Si wafers to demonstrate the range of applications that can be addressed with this technique.