“Mask Enhancer” Technology on ArF Immersion Tool for 45-nm-Node Complementary Metal Oxide Semiconductor with 0.249 µm² Static Random Access Memory Contact Layer Fabrication

Abstract

One of the most challenging issues for 45-nm-node contact hole printing is to ensure a sufficient process window required for day-to-day manufacturing, and to reduce large mask error enhancement factor (MEEF) to keep the critical dimension (CD) controllable. In this study, we propose a new phase-shifting mask for random layout contact hole printing, named Mask Enhancer. By applying the Mask Enhancer, we can enhance image contrast for both isolated and dense contact holes at the same time. In addition, the Mask Enhancer is extendable for a random layout including diagonally placed or non-square contact hole. In this paper, we show the principle of the Mask Enhancer for improving image contrast and we discuss the lithographic performance of the Mask Enhancer comparing it with that of the attenuated phase-shifting mask (Att-PSM). Furthermore, we demonstrate 0.249 mm 2 static random access memory (SRAM) contact layer printing which is a 45-nm-node requirement, combining it with the immersion exposure technology on a 0.85 numerical aperture (NA) ArF immersion tool.

Fundamental Study of the Mask Topography Effect on the Advanced Phase-Shifting Masks for Next-Generation Lithography

“…Advanced phase-shifting masks with a trench-or mesa-type quartz etched structure, such as pixelated mask, 1) chrome less phase shifting mask (CPL) with interference mapping lithography (IML) [2][3][4] and mask enhancer (ME), [5][6][7][8] are widely known as powerful resolution enhancement technologies for advanced lithography. For 32 nm node ArF lithography and beyond, the feature size on a mask including a phase shifter is beyond the wavelength of the light source.…”