Continuous and Collective Grain Rotation in Nanoscale Thin Films during Silicidation

Abstract

Texture evolution is an important issue in materials and nanosciences. Understanding it is fundamental for controlling the final orientation, which in fine controls the desired properties of nanodevices. Here, we reveal the formation of a peculiar texture during the silicidation of nanoscale Pd thin films. We demonstrate that the crystallographic relationship observed between the silicide and the Si(001) substrate, named gyroaxy, evolves continuously and collectively during silicidation. This continuous rotation of the nanosized grains over a wide angular range is proposed to be associated with a diffusional mechanism.

Interfacial Silicide Formation and Stress Evolution during Sputter Deposition of Ultrathin Pd Layers on a-Si

“…The deposition of Pd on a-Si and c-Si [referring mainly to the well-studied Si(111) and Si(100) surfaces] shows many similarities: in both cases, Pd reacts instantly with the Si surface atoms, reducing thus the thickness of the underlying silicon layer. , Independent of the substrate crystallinity, the minimum thickness of the resulting silicide interlayer is around 3–5 nm, ,,, and XPS/AES measurements confirm that the electronic environment at the Pd/c-Si , and Pd/a-Si interfaces is similar.…”

“…Numerous studies focus on the silicide formation during post-growth annealing including, e.g., refs , − . With the ongoing miniaturization of microelectronic devices, however, the interface formation during deposition becomes increasingly relevant.…”

“…Depending on the envisioned application, the metal films are thermally evaporated or deposited by magnetron sputtering on amorphous (a-Si) or crystalline (c-Si) silicon surfaces. Only few authors report on the deposition of Pd on a-Si at room temperature. ,− It was found that the chemical reaction between Pd and c-Si occurs instantly during deposition and is already activated at 150 K. , During early growth stages, several reports propose the formation of amorphous silicide on c-Si. − For thicker Pd layers, epitaxial Pd 2 Si­(001) was found on Si(111). ,,, Layers with gyroaxial texture were observed on Si(100) …”

Texture in thin film silicides and germanides: A review

“…So far, there has only been one, very recent observation reported in literature of a silicidation reaction where the orientation of the grains of a single phase changes after nucleation. For 50 nm Pd films deposited on Si(001), Richard et al 107 observed the formation of a peculiar texture when the Pd 2 Si phase forms. The initially formed Pd 2 Si layer showed four orientation variants and a large tilt (19:5 ) of the c-axis with respect to the surface normal.…”

Grain growth rate for coupled grain boundary migration and grain rotation in nanocrystalline materials

“…Alternatively, grains in polycrystalline materials undergoing large (superplastic) deformations at high homologous temperatures and subgrains during recrystallization have also been observed to rotate to accommodate the deformation [6]. At smaller length scales, grains in NC materials have been experimentally observed to rotate at low stresses and temperatures [7][8][9][10][11][12][13][14][15][16]. Grain rotation at these smaller length scales allows accommodation of plastic deformation which could play an important role in improving ductility [17].…”