Investigation of Immersion Alignment Mark Signal and Alignment Success Rate for Flat Optics with Aperture on Chip

Flat optics allows the control of the amplitude, phase, and polarization of light at the nanoscale, which enables the realization of various optical functions with much smaller footprints than those of the bulk optics counterparts. However, while flat optics designs have been demonstrated for various optical elements, integrating different flat-optics sub-systems remains challenging due to the required precision for their mountings. Here, we demonstrate a fabrication flow to address such integration challenges, specifically a mass-producible semiconductor process flow for flat optics comprising high aspect ratio (HAR) dielectric nanopillars with spacing as small as 60-nm, integrated with on-chip aperture for improved image quality. We focus on strategies to overcome the challenges facing the Nikon 193nm ArF immersion scanner in aligning various layers. Alignment Mark (AM) signal quality is investigated with different process sequences for successful alignment and good overlay between pillars and aperture layers to yield functional optics device.