Abstract: At present, 5G communication, augmented reality, virtual reality, Internet of Things, new energy vehicles and other fields are developing rapidly, which depend on storage technologies, and the demand for storage is also growing. When dynamic random access memory (DRAM) sizes are scaled down to 20 nm, DRAM memory arrays face significant scaling challenges, and local critical dimension uniformity (LCDU) is particularly important in this context. This paper primarily focuses on optimizing LCDU by the dry etching process in litho-etch-litho-etch (LELE) using domestic equipment. The research results show that the combination of in-situ deposition, asynchronous etching, and asynchronous in-situ deposition and etching can significantly reduce the normalized LCDU after etching from 21.2% to 7.7%, which is 2.3% lower than that of the original American tool, laying a solid foundation for the improvement and cost reduction of DRAM core structural testing and wafer testing and boosting confidence in the development of domestic equipment.
Keywords: in-situ deposition; in-situ deposition and etching; asynchronous pulsing; local critical dimension uniformity(LCDU); dry etching