Ultra-low dielectric constant low density material (k=2.2) for Cu damascene

We have examined film properties of ultra-low dielectric constant low-density spin on glass with a dielectric constant of 2.2 (SOG-2.2). SOG-2.2 can stand higher shear strength and demonstrates better adhesion with PE-SiON than PE-SiN in scratch test. However, SOG-2.2 is damaged by conventional O2 plasma for photoresist stripping and also by wet processes for polymer removal. Using N2/H2 plasma for resist stripping, the damage can be minimized and moisture adsorption is significantly reduced, as evident in FTIR. In this work, SOG-2.2/Cu single damascene has been developed which demonstrates line-to-line capacitance reduction of 50%, compared with USG/Cu single damascene. Though there is leakage current in 0.23 μm narrow spacing Cu line, TEM examination suggests that no Cu diffusion in low density SOG-2.2 inter-metal dielectric