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

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 TiO_xN_y 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.