Atomic layer deposition of oxide semiconductor thin films for transistor applications: a review

The accelerated evolution of artificial intelligence (AI) and semiconductor technologies has fostered a mutually reinforcing relationship, whereby each technology has contributed to the advancement of the other. However, the advancement of semiconductor technology is currently hampered by the lateral scaling limitations of silicon-based transistors, creating a bottleneck for mutual advancement. Innovative channel materials capable of increasing transistor/cell density through vertical integration processes are required for continued advances in semiconductors and AI. Oxide semiconductors are prime candidates for back-end-of-line (BEOL)-compatible thin-film transistors (TFTs), which are essential for vertically stackable 3D device technologies due to their excellent electrical properties and compatibility with atomic layer deposition (ALD). In this review, we explore the latest developments in ALD-derived n- and p-type oxide TFTs, with a particular focus on performance enhancement strategies including composition modulation, interface and surface engineering, ion doping, and process control. The integration of oxide semiconductors via ALD is of the utmost importance for contemporary semiconductor devices, as it enables the implementation of vertical CMOS logic circuits and advanced memory technologies, including 3D-DRAM. Our findings indicate that ALD-derived oxide semiconductors have the potential to overcome current limitations and facilitate the development of the next generation of high-performance, vertically integrated semiconductor devices.