A hybrid additive with both suppressor and leveler capability for damascene copper electrodeposition

Additives are essential for damascene copper electroplating to achieve defect-free deposition in nanoscale interconnect on chips. A hybrid additive named 1000EQ with capabilities of both suppressor and leveler has been synthesized and analyzed. The additive contains polyether segment and nitrogen cation which are typical functional groups of suppressor and leveler, respectively. Electrochemical measurements reveal that 1000EQ has strong inhibition toward copper deposition and is more resistant to the desorption of accelerator than traditional suppressor polyethylene glycol (PEG, Mw  = 10,000). 1000EQ and bis-(sodium sulfopropyl)-disulfide (SPS) were used as additives to achieve a defect-free filling of features with 70 nm in width and an aspect ratio above 3. The ratio of copper film thickness over dense and sparse patterned area is close to 1 and the root mean square roughness (Rq) of the film is 9.4 nm, acting as a solid proof of its hybrid characteristic. The resistivity of the copper film is 1.80 ± 0.02 µΩ cm. The characterizations establish that 1000EQ is a promising candidate which can serve as both suppressor and leveler for damascene copper electrodeposition and is able to simplify the bath used in copper electrodeposition process.