The semiconductor industry is currently driven by a computing power revolution necessitated by the rapid expansion of Generative AI. Since 2010, the compute required to train notable AI models has doubled approximately every six months, leading to a projected total data volume of 181 Zettabytes by 2025. Within this ecosystem, High Bandwidth Memory (HBM) serves as the critical memory solution due to its superior bandwidth-to-power efficiency compared to conventional DDR5 or GDDR6 architectures. HBM utilizes a stacked die architecture interconnected via Through-Silicon Vias (TSVs) on a logic die to minimize signal paths and maximize I/O density.  

Conventional 2D DRAM scaling is approaching a fundamental limit at sub-10nm nodes due to patterning constraints and the difficulty of maintaining cell capacitance (Cs). To bypass these physical limitations, the industry is transitioning toward 4F2 Vertical Gate (VG) DRAM and Lateral 3D DRAM architectures. The 4F2 VG DRAM utilizes a Periphery-under-Cell (PUC) architecture where the cell wafer and periphery wafer are joined via fusion bonding, effectively separating the bitline and storage node contacts to enhance scalability. Concurrently, lateral 3D DRAM architectures are being developed to provide sufficient spatial margin for capacitors and on-current, with experimental 32-layer test chips already demonstrating viable device performance.  

The transition to these advanced architectures significantly elevates the role of Atomic Layer Deposition (ALD) from providing functional films to also providing structural backbone films. Structural films such as spacers and capacitor supporters must now meet rigorous chemical stability and thermal budget requirements while maintaining precise atomic-level control. 4F2 VG cells face challenges in high-aspect-ratio pillar formation and gap-fill, whereas 3D DRAM structures are constrained by lateral process control and the costs associated with thick epitaxial stacks.  

The long-term "Revolutionary Path" for DRAM involves a transition toward monolithic integration through stackable channels and alternative storage mechanisms. This includes replacing single-crystal silicon with amorphous metal oxides (e.g., IGZO) or 2D materials like MoS2, which offer more flexible deposition despite current challenges in trap density and grain boundaries. Furthermore, the integration of ferroelectric materials (e.g., HZO) into capacitors is being explored for non-volatile applications, alongside research into capless DRAM designs such as Thyristor-based or FeFET-based transistors to eliminate the scaling bottleneck of the traditional capacitor.