Abstract
As the device’s size in integrated circuits steps into deep sub-half micron regime, multilevel interconnection structures become more complex and interconnection lines become thinner and narrower. The present used aluminum(Al) interconnection line is going to suffer from high performance and interconnection reliability problems. The demands for lower resistivity and better reliability in interconnection are more stringent in integrated circuits. Copper (Cu) has been considered as the most suitable interconnection metal to substitute Al because of its low electrical resistance, superior electromigration resistance, Among the various deposition methods, Cu chemical vapor deposition (Cu CVD) is thought to be a promising technique to deposit Cu films because of its superior conformal step coverage in small contact hole/via with high aspect ratio. However, the Cu film deposited by CVD always exhibit higher resistivity due to the contamination from its metal organic source. It has been found that lower contamination in CVD Cu films can be obtained if lower deposition temperature is used. Hence, in this work, we tried to deposit CVD Cu films at lower deposition temperature for the first time by using photo-assisted CVD method. The photo-assisted Cu CVD system was constructed and the deposited Cu films were characterized. In this work, we demonstrated the feasibility of using photo-assisted CVD to deposit Cu film at lower deposition temperature (~100℃). By using Glow Discharge Spectrometer(GDS), we found that lower carbon (C)contamination and hence lower resistivity can be achieved in the Cu films grown by photo-assisted CVD method at a temperature as low as 100 ℃. The photo-assisted CVD Cu films were also analyzed by XRD, α-stepper, AFM, SEM for investigation of their orientation, resistivity, roughness and grain size.