Impact of UV wavelength and curing time on the properties of spin-coated low-k films

Advanced spin-on k 2.3 films with similar to 40% porosity were enabled by liquid phase self-assembly (LPSA) mechanism on Si substrates. UV-assisted thermal template removal is investigated as a faster alternative to the conventional thermal process. The as-deposited films were exposed to narrow-band UV light of 172 nm, 222 nm, 254 nm or 185/254 nm at 400 degrees C for different time. The optical, mechanical, chemical and electrical properties of the resulting films are discussed in this work. Photons with wavelength of about 172 nm from one side are detrimental to the electrical and chemical properties of the low-k films hut from the other side notably improve the porous low-k mechanical properties. Exposure to 222 nm light as short as 3 min, is more efficient in terms of template removal when compared to 2h thermal cure, while in both cases similar mechanical and electrical properties are reported. UV-cure using 254 nm or dual band 254/185 nm photons seem to have a minor contribution to the template removal efficiency for the applied doses. Higher doses are necessary in order to better understand the effective contribution of these photon energies. Finally, the HF etching mechanism is discussed

Laser anneal of oxycarbosilane low-k film

Submilisecond laser anneal has been experimentally investigated for porogen removal and its ability to improve the mechanical strength in oxycarbosilane ultra low-k films compromised due to the introduction of porosity. We report the occurrence of extensive bond rearrangements inferred from Fourier-transform infra-red (FTIR) spectroscopy, elastic recoil detection (ERD) and spectroscopic ellipsometry (SE) in the energy range of 1.4-8 eV. The laser anneal affects most notably the organic content of the organosilicate matrix leading to depletion and reorganization. Nevertheless, the tested conditions reveal a processing window which allows for 13% improvement of Young’s modulus as compared to the reference film, annealed in a conventional furnace at 400°C for 2 h, while not impacting the relative dielectric constant of 2.25

Can the intake of antiparasitic secondary metabolites explain the low prevalence of hemoparasites among wild Psittaciformes?

Background: Parasites can exert selection pressure on their hosts through effects on survival, on reproductive success, on sexually selected ornament, with important ecological and evolutionary consequences, such as changes in population viability. Consequently, hemoparasites have become the focus of recent avian studies. Infection varies significantly among taxa. Various factors might explain the differences in infection among taxa, including habitat, climate, host density, the presence of vectors, life history and immune defence. Feeding behaviour can also be relevant both through increased exposure to vectors and consumption of secondary metabolites with preventative or therapeutic effects that can reduce parasite load. However, the latter has been little investigated. Psittaciformes (parrots and cockatoos) are a good model to investigate these topics, as they are known to use biological control against ectoparasites and to feed on toxic food. We investigated the presence of avian malaria parasites (Plasmodium), intracellular haemosporidians (Haemoproteus, Leucocytozoon), unicellular flagellate protozoans (Trypanosoma) and microfilariae in 19 Psittaciformes species from a range of habitats in the Indo-Malayan, Australasian and Neotropical regions. We gathered additional data on hemoparasites in wild Psittaciformes from the literature. We considered factors that may control the presence of hemoparasites in the Psittaciformes, compiling information on diet, habitat, and climate. Furthermore, we investigated the role of diet in providing antiparasitic secondary metabolites that could be used as self-medication to reduce parasite load. Results: We found hemoparasites in only two of 19 species sampled. Among them, all species that consume at least one food item known for its secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, were free from hemoparasites. In contrast, the infected parrots do not consume food items with antimalarial or even general antiparasitic properties. We found that the two infected species in this study consumed omnivorous diets. When we combined our data with data from studies previously investigating blood parasites in wild parrots, the positive relationship between omnivorous diets and hemoparasite infestation was confirmed. Individuals from open habitats were less infected than those from forests. Conclusions: The consumption of food items known for their secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, as well as the higher proportion of infected species among omnivorous parrots, could explain the low prevalence of hemoparasites reported in many vertebrates

Diffusion growth of Cu3Sn phase in the bump and thin film Cu/Sn structures

Monitoring the intermetallic interfacial growth in Cu-Sn interconnects is crucial from reliability point of view. In this work the increase of Cu 3Sn thickness has been monitored during ageing for two different types of sample with flip-chip scale dimensions. The ageing was performed in the temperature range from 150 to 300 °C with different durations. Based on the thickness growth measurement, values of diffusion parameters were calculated. The obtained results exhibit that the processing route plays an important role in the growth of intermetallics in the Cu-Sn system. © 2012 Elsevier Ltd. All rights reserved.status: publishe

Improvement of cohesion strength in ULK OSG materials by pore structure adjustment

© 2015 Elsevier B.V. All rights reserved. In this study cohesion strength in low-k dielectric films was enhanced by tuning the pore structure. The correlation between the average size of pores in ultra-low-k materials and cohesion energy was demonstrated by performing a 4-point bending test on multi-layer structures including TaN/Ta metal barrier. Spin-on organosilica films prepared with different templating surfactants were used to alleviate porosity- pore size coupling, which revealed the particular role of pore size with respect to material toughness. The paper also discusses aspects of material design at precursor level.status: publishe