Damage to OSG low-k films during IPVD deposition of the Ta barrier layer

The degradation of a porous organosilicate glass low-k dielectric during the ionized physical vapor deposition of tantalum coating is studied. The main contribution to the damage is made by vacuum UV flux (10(14)-10(15) s(-1) cm(-2)) from the argon inductively coupled plasma of the ionizer, and the effect of the direct current magnetron sputter plasma is small. The damage by vacuum ultraviolet photons with an energy exceeding the band gap of the SiO2 matrix is associated not only with the removal of carbon-containing groups (terminal CH3 and bridging CH2) but also with the breaking of Si-O bonds in the Si-O-Si matrix followed by the formation of hydrophilic Si-OH and Si-H groups. Consequently, the degree of damage can be much higher than would be expected from the depth of CH3 group depletion.