Self‐Assembled Monolayer‐Free Area‐Selective Atomic Layer Deposition for Confined Structure Integration of High‐Reliability 3D Phase‐Change Memory

Abstract 3D phase‐change memory (3D‐PCM) has gained prominence as a scalable non‐volatile memory technology, initially demonstrated in the XPoint architecture. However, its complex fabrication and limited stackability restrict further scaling. To ease fabrication, the industry has adopted 3D‐NAND‐inspired non‐confined vertical electrode structures, in which chalcogenide phase‐change materials (PCMs) are continuously deposited along via sidewalls with obvious leakage current and thermal cross‐talk, limiting device reliability and integration density. In this work, confined vertical electrode architectures are realized that break through the scalability bottlenecks of conventional architecture. Guided by a detailed investigation of precursor adsorption behavior on metal and dielectric surfaces, the Surface Reactivity‐Gated Chemisorption (SRGC) mechanism is elucidated. Based on that, a self‐assembled monolayer (SAM)‐free, area‐selective atomic layer deposition (AS‐ALD) strategy is developed that enables precise PCMs growth exclusively within SiO2‐encapsulated W recesses, achieved through controlled plasma activation and precursor saturation tuning, which circumvents the challenges of traditional top‐down processes. The innovative structure reduces inter‐cell leakage current by six orders of magnitude, supports theoretical stacking of over 300 layers‐a 40× increase compared to XPoint architecture, and maintains stable electrical performance over 4 × 10 6 cycles. This approach offers a scalable and manufacturable path toward high‐density, reliable 3D‐PCM architectures.