The Effect Of O Plasma Treatment On Porous SiCOH Films

As the device dimension continuous shrinking in ultralarge-scale integrated circuits (ULSI), the resistance-capacitance (RC) delay of interconnects becomes a major problem, which leads to signal propagation delay, dissipation and cross-link between metal interconnects. In order to address the problems, the Al/SiO2 structure must be replaced with low dielectric constant materials and low resistivity metal interconnects. As the substitution of SiO2, the porous low dielectric constant (low-k) and ultra-low dielectric constant (ultralow-k, k < 2) materials have received more close attention recently. Meanwhile, copper has been adopted as the substitution of Al interconnects in ULSI due to its lower resistivity.However, the integration of Cu/SiCOH porous low-k dielectrics remains challenging. Owing to the existence of open pores at the surface of SiCOH low-k films, the diffusion of Cu to porous SiCOH low-k films can take place under the action of bias or thermal treatment. It will lead to the increase of leakage current and the deterioration of electrical property.Due to the existence of Si dangling bonds at the surface of porous SiCOH films, if we increase the linkage of Si dangling bonds by O2 plasma treatment, the more open pores may be sealed. In this paper, the effect of O2 plasma treatment on the leakage current of Cu/SiCOH integrated structure and the dielectric constant of SiCOH low-k films is investigated. The results show that the leakage current of Cu/SiCOH structure can be reduced greatly by O2 plasma surface treatment at the expense of the slight increase of dielectric constant k. By the FTIR analysis, the decrease of leakage current is proved to relate to the increase of closed pores.