Influence of Etch Profiles on the Leakage Current and Capacitance of 3-D DRAM Storage Capacitors

The influence of etch profiles on leakage current and capacitance of three-dimensional (3-D) dynamic random access memory (DRAM) storage capacitors is investigated by using full 3-D technology computer-aided design (TCAD) simulation. According to the simulation results calibrated by experimental data, as the ratio of bottom critical dimension (CDBOT) to top critical dimension (CDTOP) of a DRAM storage capacitor decreases, storage capacitance (C-s) decreases while leakage current (I-leak) increases. Thus, it is important to achieve steep etch profiles during the fabrication of DRAM storage capacitors for higher DRAM capacity and longer refresh time.