RECENT DEVELOPMENTS IN ALD TECHNOLOGY FOR 50nm TRENCH DRAM APPLICATIONS

摘要

Key ALD technologies required for the scaling of DRAM trench capacitors below 50nm are demonstrated. The main focus in this article is on the introduction of HfSiO as a dielectric material for deep trench capacitors in combination with the development of an ALD process for this application. Here, the special selection procedure for precursors used for deposition of films in high aspect ratio structures and their implementation in ALD processes will be described, which results in specific requirements for the ALD precursors. Quantum mechanical calculations were used to model reaction chemistry and to understand critical differences between precursors. Electrical properties of an HfSiO/TiN MIS film stack for capacitor applications will be presented showing excellent capacitance values and reliability results for future DRAM applications.