MIM Capacitors Featuring Low EOT and Low Leakage Current Density by Nitrogen-Incorporated HfO₂/ZrO₂/HfO₂

A HfO₂/ZrO₂/HfO₂ (HZH) high-k stack with adequate ZrO₂ thickness ratio is proposed as dielectric in metal-insulator–metal (MIM) capacitor for dynamic random access memory (DRAM) applications. The dielectric constant (k) of 43 is achieved when the ZrO₂ thickness ratio is 73%. An equivalent oxide thickness (EOT) of 0.46 nm and leakage current density ( ${J} _{\text {g}}$ ) of $9.4\times 10^{-{5}}$ A/cm² are simultaneously achieved with a total HZH physical thickness ( ${T} _{\text {ox}}$ ) of 5 nm. The leakage current may be caused by the interface traps at the HZH multi-interface structure, as well as the oxygen vacancies inside HfO₂ and ZrO₂. To suppress ${J} _{\text {g}}$ , a NH₃ plasma treatment was in situ conducted during atomic layer deposition (ALD) processes of HZH deposition. Through nitrogen incorporation with in situ NH₃ plasma treatment, the oxygen vacancies can be passivated, and Zr-O–N bonds would be formed at the interface to suppress the formation of interface traps. The sample with an in situ NH₃ plasma treatment at the interface between ZrO₂ and top HfO₂ (ZN) can obtain a reduction in leakage current density by 48% when compared with those without ZN, while maintaining the capacitance density (C) at a similar value of around $7.4~\mu $ F/cm². The approaches of HZH stack and in situ plasma treatment for MIM capacitor are promising to the cell in DRAM technology.