Oxygen‐Tunnel Indium Tin Oxide Vertical Channel Transistors with Enhanced Current Density and Reliability for Monolithic 3D Compute‐In‐Memory Systems

Monolithic three‐dimensional integration demands embedded memory technologies that achieve extreme density scaling under limited back‐end‐of‐line thermal budget. Atomic layer deposition‐grown amorphous oxide semiconductors (AOS) are attractive for this purpose because of their excellent conformality and intrinsically low off‐state current I OFF, enabling vertical channel transistors (VCTs) for capacitor‐less gain‐cell memory operation. However, in VCT, oxygen‐deficient AOS channels required for low leakage and high conductivity coexist with oxygen‐rich dielectric sidewalls, introducing a fundamental materials‐stack challenge associated with oxygen‐vacancy‐induced instability and parasitic oxidation at electrode interfaces. Indium tin oxide (ITO) offers a balance between low leakage and high carrier mobility, yet is particularly vulnerable to oxygen‐migration‐induced degradation in vertical geometries. Here, we introduce an oxygen‐tunnel stack based on SiN/SiO 2 /SiN layers that spatially regulates oxygen transport. This architecture stabilizes oxygen vacancies in the ITO channel while suppressing electrode oxidation, enabling a record‐high current density of 436 µA/µm and a negligible threshold voltage shift of less than 50 mV after 10 7 bias‐stress cycles. A gain‐cell memory demonstrated retention exceeding 648 s and endurance beyond 1200 cycles enabled by the exceptionally low I OFF of 2.6 × 10 −19 A/µm. A Si‐ITO hybrid gain‐cell integration framework was developed and evaluated, demonstrating the feasibility and system‐level benefits of incorporating oxygen‐regulated ITO VCTs into Si‐based embedded memory and compute‐in‐memory architectures.