Atomic Layer Deposition of Textured ZnO on 200 mm Wafers for Device Applications

Zinc oxide (ZnO) is a technologically important wide-bandgap semiconductor used in optoelectronics, sensing, and transparent electronic devices. Implementing ZnO thin films in such devices requires scalable, uniform, and compatible thin-film deposition methods. Atomic layer deposition (ALD) provides precise control over film thickness, composition, and conformality, and is a well-adapted process in the semiconductor industry. ALD processes for growing ZnO primarily rely on the pyrophoric diethylzinc (DEZ) precursor. Recently, Bis-3-(N,N-dimethylamino)propyl zinc ([Zn(DMP)2]) has emerged as a promising non-pyrophoric alternative, providing improved handling safety and enhanced thermal stability. However, its use has so far been limited to growth on small substrates in proof-of-concept experiments. In this work, a thermal ALD process using [Zn(DMP)2] with H2O as precursors was developed on industrially-relevant 200 mm silicon wafers and compared to an established thermal process with DEZ and H2O. The effects of deposition temperature (150-300 °C), film thickness, and the underlying substrate material on film growth were systematically investigated. Structural, morphological, chemical, and electrical properties were evaluated using complementary and advanced materials characterization techniques. Across the entire 200 mm wafer area, ZnO films deposited from [Zn(DMP)2] exhibit excellent thickness uniformity and a nearstoichiometric composition comparable to those obtained with DEZ. While slightly higher resistivity and reduced crystallinity are seen at lower deposition temperatures, higher deposition temperatures yield comparable resistivity and an improved c-axis oriented crystalline texture. Importantly, successful lithographic patterning and electrical characterization of van der Pauw devices confirm compatibility with advanced fabrication workflows. These results demonstrate that [Zn(DMP)2] can compete with DEZ in film quality on large-area wafers and is safer to handle, which is a significant advantage overall.