The primary x-ray diagnostic lines in He-like ions are mainly excited by electron impact from the ground level to the n = 2 levels, but at high temperatures n > 2 levels are also excited. In order to describe the atomic processes more completely, collision strengths are computed for O VII including for the first time all of the following: (i) relativistic fine structure, (ii) levels up to n = 4, and (iii) radiation damping of autoionizing resonances. The calculations are carried out using the Breit-Pauli R-matrix method with a 31-level eigenfunction expansion. Resonance structures in collision strengths are delineated in detail up to the n = 4 thresholds. For highly charged He-like ions radiation damping of autoionizing resonances is known to be significant in certain energy ranges. We investigate this effect in detail and find that while resonances are discernibly damped radiatively as the series limit n → ∞ is approached from below, the overall effect on effective cross sections and rate coefficients is found to be very small. Collision strengths for the principal lines important in xray plasma diagnostics, w, x, y and z, corresponding to the four transitions to the ground level 1s 2 ( 1 S 0 ) ←− 1s2p( 1 P o 1 ), 1s2p( 3 P o 2 ), 1s2p( 3 P o 1 ), 1s2s( 3 S 1 ), are explicitly shown. Significant differences are found with previous works for several transitions. The contribution from the resonances converging to the levels from the complex n = 4 is found to be significant for some transitions and can increase the rate by a factor of four. This work is carried out as part of the Iron Project-RmaX Network.

Copper (Cu)/low-k interconnects were fabricated using novel Cu diffusion-barrier SiC films deposited with a novel precursor, 1,1-divinylsilacyclopentane (DVScP). At 46% overetching time, the yield of the via-contact with the dielectric barrier of conventional SiC films was seriously reduced, while that of the novel SiC films was hardly reduced. By using the novel SiC films, the thickness of diffusion barriers was successfully reduced to 15 nm, matching the 32 nm node and beyond. By using the novel SiC films, the dielectric constant of the barrier films was decreased and their thickness was reduced with no yield reduction of the via-contact. As a result, the product of wiring resistance and capacitance (RC product) was reduced by 11.4%. The time-dependent dielectric breakdown (TDDB) lifetime of Cu interconnects with the SiC films was similar to that with the SiCO films. #

We propose new precursors for bulk low-k films with plasma damage resistance. Our newly designed precursors contain long-chain hydrocarbon groups such as i-butyl and n-propyl groups. Using these precursors, we successfully produced films containing Si–CH2–Si groups by plasma-enhanced chemical vapor deposition (PECVD). The plasma damage resistance of these films under NH3 plasma treatment was studied. It was found that the increase in the k-value (Δk) is smaller in films with more Si–CH2–Si groups.

No abstract