Electroless copper deposition for ULSI

This work reviews the electroless copper deposition process as a metallization method for integrated circuit applications. We review the solution chemistry and reaction thermodynamics as well as the deposition kinetics for deposition on flat surfaces and on patterned surfaces with minimum dimensions between 0.1 and 1.0μm. The development of an alkali-free solution for sodium-free copper deposition is presented and the optimization of this solution for minimum as-deposited film resistivity is described. The integration of electroless technology in integrated circuit production is discussed and two basic approaches are presented, planar and non-planar. Finally, process flows for several integration methods are summarized and discussed.