Thus, the potential shift to the positive value can take a place in cases of incomplete Cu reduction or dissolution of the deposited Cu [25]. As we have observed the greatest amount of Cu2O for the bulk Si (100) sample, the incomplete reduction of the adsorbed Cu ions is more likely to happen. Figure 6 OCP vs immersion time. (curve a) Cu/Si (100), (curve b) Cu/PS/Si (100), (curve c) Cu/Si (111), and (curve d) Cu/PS/Si (111). Conclusions We studied the initial stages of Cu immersion deposition from the aqueous solution of Cu sulfate in the presence of hydrofluoric acid on bulk and porous silicon. The analysis of top-view SEM images of the samples revealed that Cu deposited both on

the bulk and porous silicon as a layer of NPs in accordance with the Volmer-Weber mechanism. The size distribution selleck compound of Cu NPs for all samples had a bimodal character and a minimum peak between 40 and 50 nm. The Si (100) substrate allowed the depositing of Cu particles of the largest sizes that reached the range of 200 to 210 nm. The smallest Cu NPs were detected on Si (111). The densities of Cu NPs on Si (100) and Si (111) differed greatly and were 109 and 1010 cm−2, respectively. At the same time, the PS substrates resulted in the almost equal sizes and densities

of Cu NPs. EBSD analysis showed that Cu NPs grew as crystals with a maximum size of 10 nm and inherited the orientation of the original silicon substrate. We suppose that this fact

partially promotes the improvement of thick metal films’ adhesion MG-132 mouse to Si substrates previously covered with Cu/PS layer [11, 12]. In addition, EBSD detected crystals of Cu2O on all samples, but Cu NPs on Si (100) were the most oxidized. Moreover, Cu deposited on the porous substrates demonstrated greater stability to the oxidation in contrast with bulk Si. Consequently, the crystal orientation of the original Si wafer significantly affected many the sizes, density, and oxidation level of Cu NPs deposited by immersion technique only on bulk Si in contrast to PS. The possibility to control the structural parameters and oxidation stability of Cu NPs on bulk and porous Si can allow the improvement of the adhesion and conductive characteristics of metal interconnections. We suppose as well that the revealed regularities of Cu immersion deposition are valid for the other metals of cubic lattice cell. Acknowledgments This research was partially supported by the Belarusian Foundation for Basic Research under the Project T11OB-057, by Rise Technology S.r.l. (Roma, Italy) and by the European Union under the project “BELERA”. References 1. Canham L: Properties of Porous Silicon. London: INSPEC; 1997. 2. Herino R: Nanocomposite materials from porous silicon. Mater Sci Eng 2000, B69–70:70–76.CrossRef 3. Morinaga H, Suyama H, Ohmi T: Mechanism of metallic particle growth and metal-induced pitting on Si wafer surface in wet chemical processing.