UV-B radiation amplification factor determined based on the simultaneous observation of total ozone and global spectral irradiance

The Japan Meteorological Agency started the spectral observation of solar ultraviolet (UV) irradiance on 1 January 1990 at Tateno, Aerological Observatory in Tsukuba (35 deg N, 140 deg E). The observation has been carried out using the Brewer spectrophotometer for the wavelengths from 290 to 325 nm with a 0.5 nm interval every hour from 30 minutes before sunrise to 30 minutes after sunset throughout a year. Because of remarkable similarity within observed spectra, an observed spectrum can be expressed by a simple combination of a reference spectrum and two parameters expressing the deformation of the observed spectrum from the reference. By use of the relation between one of the deformation parameters and the total ozone simultaneously observed with the Dobson spectrophotometer, the possible increase of UV irradiance due to ozone depletion is estimated. For damaging UV, the irradiance possibly increases about 19 percent with the ozone depletion of 10 percent at noon throughout the year in the northern midlatitudes. DUV at noon on the summer solstice possibly increases about 5.6 percent with the ozone depletion of 10 m atm-cm for all latitudes in the Northern Hemisphere

Highly Conformal Amorphous W–Si–N Thin Films by Plasma-Enhanced Atomic Layer Deposition as a Diffusion Barrier for Cu Metallization

Ternary and amorphous tungsten silicon nitride (W-Si-N) thin films were grown by atomic layer deposition (ALD) using a sequential supply of a new fluorine-free, silylamide-based W metallorganic precursor, bis(tert-butylimido)bis(bis(trimethylsilylamido))tungsten(VI) [W(NtBu)(2){N(SiMe3)(2)}(2)], and H-2 plasma at a substrate temperature of 300 degrees C. Here, W(NtBu)(2){N(SiMe3)(2)}(2) was prepared through a metathesis reaction of W(NtBu)(2)Cl-2(py)(2) (py = pyridine) with 2 equiv of LiN(SiMe3)2 [Li(btsa)]. The newly proposed ALD system exhibited typical ALD characteristics, such as self-limited film growth and linear dependency of the film growth on the number of ALD cycles, and showed a high growth rate of 0.072 nm/cycle on a thermally grown SiO2 substrate with a nearly zero incubation cycle. Such ideal ALD growth characteristics enabled excellent step coverage of ALD-grown W-Si-N film, similar to 100%, onto nanotrenches with a width of 25 nm and an aspect ratio similar to 4.5. Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy analysis confirmed that the incorporated Si and W were mostly bonded to N, as in Si-N and W-N chemical bonds. The film kept its amorphous nature until annealing at 800 degrees C, and crystallization happened at local areas after annealing at a very high temperature of 900 degrees C. An ultrathin (only similar to 4 nm thick) ALD-grown W-Si-N film effectively prevented diffusion of Cu into Si after annealing at a temperature up to 600 degrees C