Stress evolution during the growth of ultrathin layers of iron and iron silicide on Si(111)

Abstract

Using a simple optical deflection technique, we measured continuously the mechanical stress during the growth of Fe films of 0.1–1.5 nm thickness on Si(111) in ultrahigh vacuum (UHV). The stress versus coverage dependence is discussed in view of the different growth modes during the various stages of Fe deposition. The deposition of up to 0.3 nm Fe induces a compressive stress of −1 N/m. We assign this stress to the formation of a reactive Fe–Si interface layer with a silicidelike structure. Subsequent Fe deposition at 300 K leads to a small tensile stress of 0.7 N/m, whereas the deposition at 600 K induces a high tensile film stress of 18 N/m. At 600 K substrate temperature, a solid-state reaction between Fe and Si sets in, and the silicide β-FeSi2 is formed. The decrease of the atomic volume of Si by 7% in this silicide is proposed to be the cause for the tensile stress.

Surface stress in the self-assembly of alkanethiols on gold probed .by a force microscopy technique

“…Nor can the gravimetric deflection due to the molecular loading, calculated to be ≈ 1 mV, account for the observed bending. Based on both the permanent nature of the deflection and its magnitude, we attribute the sensor response to changes in surface stress ∆σ [21][22][23].…”

Raman investigation of ion beam synthesized β-FeSi2

“…57 A qualitative explanation for the tensile stress in the ␤-FeSi 2 layers was given by Sander and co-workers. 58 This explanation was based on the decreased atomic volume of Si 2,59 when ␤-FeSi 2 is formed. The net effect of the disilicide formation is that each Si atom occupies 1.87 nm 3 instead of 2.01 nm 3 , thereby resulting in a volume reduction of about 4.5%.…”

Influence of nanometer-sized interface on reaction of iron nanocrystals epitaxially grown on silicon substrates with oxygen gas

“…[15][16][17][18][19][20][21] However, it should be noted that through the use of an interlayer of a SiO 2 with Si NWs, no silicidation was observed between the NC and Si substrate. During the Si deposition on the ultrathin SiO 2 film, NWs were created in the ultrathin SiO 2 films through the following reaction: …”

“…Epitaxial growth on Si substrates offers many advantages in terms of achieving regular crystal orientation. However, during the epitaxial growth of transition metals such as Fe on Si substrates, significant silicidation at the metal/Si interface has long been an issue, [13][14][15][16][17][18][19][20][21] where silicide formation at the interface randomizes the crystalline and electronic structure. The use of different buffer layers has been proposed to suppress silicide formation on Si substrates; however, avoiding silicidation remains challenging.…”

“…The use of different buffer layers has been proposed to suppress silicide formation on Si substrates; however, avoiding silicidation remains challenging. [15][16][17][18][19][20][21] An ultrathin SiO 2 film technique succeeded in the epitaxial growth of silicide NCs on Si substrates with a sharp interface: namely, there was no silicidation in Si substrates. [22][23][24] In this paper, we present the epitaxial growth technique of Fe NCs on Si substrates without silicidation by modifying the ultrathin SiO 2 film technique.…”