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 (Cs) decreases while leakage current (Ileak) 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.