Defect-Free Copper Filling Using Nonisothermal Electroless Deposition with Fluorocarbon Surfactant

Abstract

Electroless copper bottom-up filling of patterned substrates using nonisothermal deposition (NITD) with the addition of adequate surfactant was demonstrated. Combining the inhibitive ability of adequate surfactant with the higher driving force of NITD method, superfill of vias or trenches using only one inhibitor in the copper damascene of integrated circuits (ICs) was achieved. We tested several commercial surfactant agents and found that fluorinated alkyl quaternary ammonium iodides (FC) is best compatible to our NITD method. Void-free copper-filled features can be obtained by introducing the surfactant FC into the electroless bath of NITD. Furthermore, using our method, the conductivity of copper film was not negatively affected. We conclude that the surfactant FC combined with NITD method is very promising for the applications in filling trenches and vias with copper films in the IC industry.