Low sheet resistance buried metal bit line realized by high-temperature metal CVD process in vertical channel transistor array

Abstract

With the continuous evolution of Dynamic Random-Access Memory (DRAM) devices, there is a growing demand for increased storage density per unit area. In this work, we aim to create a high-density array of vertical channel transistors using advanced DRAM process technology. A thickness of SiO2 (X+3 nm) was determined for the protective layer, which shows best protecting effect. We employed chemical vapor deposition (CVD) to grow thin Ti films on the array's bottom. To reduce the resistance of buried bit line (BBL), we formed an high-quality metal silicide using a thermal annealing process combined with self-align technology. Nanoprobe measurements results show an average resistance of approximately 60 Ω of the bit line of each cell transistor, where the low series resistance can improve device performance. Our work involved optimizing the protective layers and achieving high-performance buried bit lines, paving the way for the development of high-density DRAMs.