Oxidation Degradation of TiN Electrodes in DRAM Capacitors and Mitigation through AlN Insertion

Given the increasing demand for the high-performance capacitors in dynamic random access memories (DRAM), boosting the dielectric constant (k) to maximize capacitance density becomes critical, which requires the mitigation of low-k interfacial oxidation layers between the TiN electrodes and the dielectrics. This study investigated the effect and the mechanism of TiN oxidation under controlled annealing conditions, which resulted in a significant decrease in the dielectric constant due to dielectric relaxation and degraded reliability. To address this issue, we introduced an AlN insertion layer as an oxygen diffusion blocking layer (ODBL), which effectively prevented interfacial oxidation. The AlN layer not only preserved the dielectric constant of the capacitors, it also reduced leakage current and enhanced device reliability. These findings systematically summarized the consequences of TiN interfacial oxidation, a common phenomenon observed in DRAM fabrication, and demonstrated the potential of AlN layers in enhancing the performance of TiN-based capacitors in advanced electronic applications.