Atomic Layer Deposition in Transistors and Monolithic 3D Integration

ABSTRACT The primary challenge facing electronics, which remain central to modern technological advancement, lies in the increasing difficulty of further dimensional scaling. Monolithic three‐dimensional (M3D) integrated can preserve the performance of conventional two‐dimensional (2D) devices while achieving higher integration density along the vertical dimension, representing a core technology for developing multifunctional, high‐density electronic systems in the More‐Than‐Moore era. Atomic layer deposition (ALD), a surface‐controlled chemical vapor deposition technique, enables atomic‐level thickness precision and uniform, conformal thin film growth over large areas and complex three‐dimensional (3D) architectures. It has become a key process for depositing substrates, high‐ к dielectrics, channel materials, and metal gate electrodes in modern semiconducting device fabrication. ALD‐based M3D architectures provide a promising platform for next‐generation 3D compute‐in‐memory systems, neuromorphic hardware, integrated photonic circuits, and flexible electronic devices. This review provides a comprehensive overview of ALD‐fabricated 2D metal oxide, high‐ к dielectric, and 2D transition metal dichalcogenide (TMDC) semiconductors, emphasizing their applications in field effect transistors (FETs) and M3D systems. We summarize the key ALD parameters (e.g., precursors, deposition temperature), as well as recent advances and remaining challenges in ALD‐enabled M3D transistors. Finally, we outline the future directions for ALD‐based transistors and their role in the broader trend toward multifunctional M3D integrated electronic systems.