Area‐Selective Silicidation: Patterning Metal Silicides from the Bottom Up

Driven by deeper insights into their nanoscale properties, the role of metal silicides in nanotechnology has recently been redefined. A central challenge in this field is the development of new methods for the controlled synthesis of low‐dimensional silicides, whose promising properties are often theoretically predicted but remain difficult to validate experimentally. To address this challenge, area‐selective (AS) silicidation is introduced as a bottom‐up approach that enables precise control over the morphology of metal silicide crystals by engineering surface defects on the substrate. The process begins with ion‐beam patterning to create defects on Si(111) and Si(100) substrates, followed by the deposition of a thin metal oxide layer as the silicide precursor. Subsequent annealing in a hydrogen atmosphere reduces the oxide to metal, which then dewets and reacts with the silicon to form a silicide. Under these conditions, the silicide selectively nucleates and grows along the artificially introduced defects, which act as potential wells and determine the shape and positioning of the resulting structures. The effectiveness of AS‐silicidation is demonstrated by the synthesis of NiSi ₂ and its extension to Cu ₃ Si, illustrating the method's broad applicability to different silicides. This multistep process directly yields structured, low‐dimensional silicides, eliminating the need for post‐synthesis nanopatterning.