Dynamic Random Access Memory (DRAM), a critical component in modern computing systems, relies heavily on the structural integrity of its active area (AA) - a fin-shaped transistor region responsible for charge transfer in memory cells. During advanced DRAM fabrication, the plasma etching process often induces shape distortions in the AA region (termed "wiggling AA"), which degrade capacitive charging/discharging efficiency and device reliability. While this phenomenon is widely observed in industry, its mechanistic origins remain poorly understood, necessitating systematic investigation to enable precision etching control. In this paper, we fabricated active area transistors of DRAM structures and characterized the etching results using three-dimensional (3D) reconstruction based on focused ion beam-scanning electron microscopy (FIB-SEM) data. In parallel, we developed a 3D etching feature profile model that correlates process parameters with structural deformation and simulated the etching process under three oxygen flow rates. By integrating experimental data and simulation results, we systematically analyzed the mechanistic origins of the wiggling AA effect and demonstrated improvement by modulating the oxygen flow rate. This study bridges the gap between empirical observations and fundamental etching mechanisms, offering actionable strategies for optimizing high-density DRAM manufacturing processes.
Hu et al. (Sat,) studied this question.