Atomic Layer Processing of MoS₂

Two-dimensional materials, including transition metal dichalcogenides (TMDs), have attracted attention for potential use in electronic, photonic, and optoelectronic applications. Molybdenum disulfide (MoS₂) is a widely studied TMD that offers potential for improving speed and efficiency in scaled electronic devices. However, advancing MoS₂ and other 2D materials into high volume device manufacturing requires scalable deposition and etching processes that are compatible with manufacturing constraints. Atomic layer deposition (ALD) and atomic layer etching (ALE) are scalable deposition processes that deposit and etch films at relatively low temperatures. Together, atomic layer deposition and atomic layer etching constitute complementary facets of atomic layer processing. Here, we report progress in combining thermal ALD and thermal ALE of MoS₂ followed by annealing to produce crystalline few-layer films. Combining the two processes offers greater control over film uniformity and thickness. Using ALD at 200 °C with MoF₆ and H₂S followed by ALE at 200 °C with MoF₆ and H₂O and post-deposition annealing in H₂S, we achieved few-layer MoS₂ films as assessed by the separation of the characteristic Raman modes of MoS₂. Using analysis of the Raman spectra for indirect assessment of defect concentrations allowed correlation of the annealing conditions to the quality of the MoS₂ films for accelerated process development. These combined thermal processes and the promising results represent progress towards the integration of MoS₂ films into device manufacturing.