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Ultra Low-dielectric-constant Materials for 65nm Technology Node and Beyond
Published online by Cambridge University Press: 17 March 2011
Abstract
Pore characteristics including pore size distribution, porosity, and pore interconnectivity of PECVD SiCOH inter- layer dielectric (ILD) materials with different dielectric constant (κ) values have been studied. Oxygen plasma damage to SiCOH low-κ films increases dramatically as the κ value decreases. Simulations showed that, compared to the ILD film, the overhead dielectric films have a significant impact on the overall effective κ (κeff) of the BEOL interconnects. Reducing the κ values of these overhead films helps to alleviate the pressure on the κ value requirement of the ILD materials while still meeting the κeff target. Ultra low-κ (ULK) PECVD hydrogenated silicon carbide (H:SiC) films with a κ of 3.0 have been studied for the etch-stop applications. Studies of the chemical composition and bonding structure suggest that less Si-C networκs are formed and more micro-porosity are incorporated in the ULK H:SiC film. The leakage current of the ULK H:SiC film is found to be about 5 times lower than the H:S iC and H:SiCN films with higher κ values. The etch rate of ULK H:SiC film using a standard SiCOH ILD etch chemistry has been found to be negligible. Such an extremely high etch selectivity maκes these films very good etch-stop layers.
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