Charge-free plasma processing using ultra-low electron temperature plasma for atomic-scale semiconductor devices

Abstract

Plasma-induced charging is a longstanding challenge in semiconductor plasma processing, especially for high aspect ratio structures. As semiconductor processes advance to sub-nanometer scales, this charging effect has become a critical bottleneck, causing defects like notching, which severely impact device performance. Despite significant efforts, this remains one of the most difficult obstacles in the development of atomic scale transistors through plasma processing. Here we present a breakthrough approach using ultra-low electron temperature (ULET) plasma generated via an inductively coupled plasma system with a DC-biased grid. Our findings demonstrate that the ULET plasma drastically reduces the charging voltage difference caused by electron accumulation during etching-from 5 V to nearly 0 V-leading to the elimination of notching, a major defect in high aspect ratio patterning. This plasma offers a scalable solution for charge-free plasma etching, which is particularly relevant for advanced 3D-DRAM, NAND flash memory development, and new atomic scale semiconductor devices. Furthermore, this deepens the understanding of plasma physics, opening new pathways for future semiconductor plasma process innovation without plasma-induced damage.