Effects of HF solution in the electroless deposition process on silicon surfaces

Abstract

We have investigated the influence of HF concentration on the initial stages of electroless deposition for various metals (Al, Au, Cu, Sn, and Pd) onto silicon using atomic force microscopy. As the HF concentration in the plating solution increased, the rate of metal deposition correspondingly increased for Au, Cu, and Pd. In the case of Au and Cu, uniformly sized nuclei comprised the first deposited layer. However for Al and Sn, deposition occurred only at sporadic sites on the surface and was independent of HF concentration. For all of the metal ion studied, deposition initiated preferentially at flaws on the surface. The electroless process indicates a direct displacement mechanism which results in the simultaneous dissolution of Si as the metal ion is reduced at the surface. For all the metal ions deposited in this manner, metal adhesion to the Si surface was poor.

Surface reactivity of Si nanowires

“…The Si wafer can not reduce the metal ions in the solution except in the presence of HF in the solution. 25,26 However, interaction of SiNWs with metal ions in solution is a complex surface electrochemistry system. Although a plausible reaction mechanism can be deduced by the reaction products, the reaction mechanism needs to be confirmed by further studies.…”

Synthesis of Vertical High‐Density Epitaxial Si(100) Nanowire Arrays on a Si(100) Substrate Using an Anodic Aluminum Oxide Template

“…The mechanism of the electroless metal deposition on Si substrates from HF solution was discussed in the literature as galvanic displacement reactions. [24,25] Exchanging electrons through the Si substrate, the reduction of metal ions as cathodic process and the oxidation of Si atoms as anodic process occur simultaneously at the Si surface. The HF-containing electroless deposition solution stabilizes the H-termination of the Si surface at the bottom of the AAO nanopores, and then the Au nucleation immediately occurs on the Si surface.…”

Controlled Electroless Deposition of Noble Metal Nanoparticle Films on Germanium Surfaces

“…[18][19][20] Germanium is of interest for technological applications because germanium layers on silicon are easily fabricated via thermal evaporation methods, and silicon-germanium heterostructures are predicted to have potential in high-speed optoelectronic applications. 21 While the vast majority of deposition bath solutions contain hydrofluoric acid as a major component, [22][23][24] recent findings in our laboratory have discovered noble metal deposition on germanium in the absence of toxic HF. The use of HF is unnecessary due to the fact that germanium oxide is soluble in water, in contrast to the silicon case.…”