Moisture Uptake Impact on Damage Layer of Porous Low-k Film in 80nm-Pitched Cu Interconnects

Introduction A porous low-k film has been introduced to reduce the interconnect capacitance as the LSI generation progress [1-2]. Since the porous low-k film has larger porosity and higher carbon content than conventional rigid films, its surface is easily damaged by processes during integration. The damage layer has lower carbon concentration and hydrophilic properties, so the moisture uptakes in it [3]. The moisture uptake into porous low-k film causes the line capacitance increase [4]. In this work, we investigated the moisture uptake impact on line capacitance and leakage current in the triple layer interconnect structure. We also estimated dielectric constant of damage layer with including moisture by the capacitance simulation. The moisture control in the damage layer in porous low-k film is very important to reduce the line capacitance and improve the line leakage current as well as damage layer reduction.