As dynamic random-access memory (DRAM) technology continues to scale down to sub-10 nm nodes, achieving high memory density and enhanced operational performance poses increasing challenges. In particular, maintaining sufficient cell capacitance and minimizing the leakage current density have emerged as key issues. To address these issues, the development of novel electrode materials and carefully engineered interfaces between high-k dielectrics and electrodes is crucial. In this study, thermal atomic layer deposition (ALD) of Sn-incorporated MoOx (TMO) films was performed using (NtBu)2(NMe)2Mo and Sn(dmamp)2 as the Mo and Sn precursors, respectively. The growth characteristics of the TMO films, particularly the interaction between the MoOx and SnOx subcycles, were systematically investigated. Controlled Sn incorporation into MoOx successively stabilized the formation of the monoclinic MoO2 phase, resulting in a smooth surface morphology and enhanced thermal and chemical stability. ALD TMO films were employed as an interface control layer (ICL) in a metal-insulator-metal capacitor to improve the interfacial properties between the (Al-doped) TiO2 and TiN bottom electrodes. ALD TMO films promoted the in situ crystallization of rutile TiO2 (with a dielectric constant of up to 156) and effectively suppressed the unwanted formation of a low-k TiOxNy layer, resulting in significant equivalent oxide thickness (EOT) scaling. Furthermore, the insertion of the TMO ICL significantly reduced the leakage current density of the (Al-doped) TiO2 films, which was attributed to the higher work function of TMO (4.7-4.8 eV) compared to that of TiN (4.5 eV) and the minimal formation of defective TiOxNy. To evaluate the scalability of the ALD TMO ICL, its thickness was varied from 20 to 1 nm. Remarkably, even at the ultrathin thickness of 1-2 nm, TMO ICL maintained high capacitance and low leakage current density, achieving an EOT of 0.58 nm and leakage current density of 2.4 × 10-7 A/cm2. These results highlight the potential of ALD-grown TMO films as ICLs in next-generation DRAM capacitors.
Lee et al. (Fri,) studied this question.