Spatially controlled interfacial engineering by area-selective atomic layer deposition of Nb2O5 for high-performance metal-insulator-metal capacitors.

As dynamic random-access memory (DRAM) capacitors scale toward dense three-dimensional architectures, interfacial dielectrics must improve the vertical ZrO2/TiN interface while remaining spatially confined to electrode regions. Non-selective Nb2O5 growth on adjacent SiN isolation regions can form lateral oxide bridges, causing parasitic inter-cell leakage. Here, we demonstrate trimethyl orthoformate (TMOF)-assisted area-selective atomic layer deposition (AS-ALD) of Nb2O5 for spatially controlled interfacial engineering of ZrO2/TiN-based metal-insulator-metal capacitors. In the TBTEMANb/O3 process, transient TMOF surface protection suppresses Nb2O5 nucleation on SiN while retaining growth on TiN, reducing the effective growth per cycle from ∼0.40 Å per cycle to 0.13 Å per cycle on TiN and 0.04 Å per cycle on SiN, with an ∼100 cycle incubation delay on SiN. Patterned TiN/SiN analysis confirmed Nb enrichment on TiN with minimal incorporation on SiN and no detectable carbon residues. When used as an Å-scale interlayer, TMOF-treated Nb2O5 suppresses ozone-induced TiOxNy interfacial degradation, resulting in higher capacitance density, reduced EOT contribution, lower leakage current, and improved breakdown behavior. In patterned test structures, non-selective Nb2O5 deposition caused pronounced inter-cell leakage through lateral oxide bridging, whereas TMOF-assisted AS-ALD spatially confined Nb2O5 to TiN regions and suppressed cell-to-cell interference. These results identify transient SP-assisted AS-ALD as an integration relevant route for coupling interface stabilization with lateral isolation in scaled DRAM capacitors.