MoS₂-assisted chemical etching of silicon in an HF/H₂O vapor

Assisted chemical etching using non-noble metal catalysts is attracting new attention for the fabrication of semiconductor micro/nanostructures. Here, we perform silicon etching in a vapor phase using molybdenum disulfide (MoS 2 ) flakes exfoliated from a natural bulk crystal. The edge plane of MoS 2 works as a catalytic active site, while its basal plane is inert. This unique feature distinguishes MoS 2 from other catalysts used in assisted chemical etching. Therefore, MoS 2 can be a promising candidate for elucidating the mechanism behind assisted chemical etching using non-noble metal catalysts. When the MoS 2 -loaded silicon substrate is exposed to an HF/H 2 O vapor, the whole silicon substrate under the MoS 2 flakes is selectively etched, forming etched hollows despite the presence of the catalytic active sites located only at the edge. This vapor-phase etching using MoS 2 flakes is expected to stimulate new fundamental research on chemical etching assisted by other non-noble metal materials.