Influence of Chemical Composition of Pyrophosphate Copper Baths on Properties of Electrodeposited Cu Films

Abstract

: Effects of chemical composition (Cu 2+, K 4 P 2 O 7 and additive concentrations) of baths on properties of Cu thin films electrodeposited from pyrophosphate copper bath were investigated. Current efficiency was increased to be near 100% with increasing Cu 2+ concentrations from 0.02 to 0.3 M. Decrease of current efficiency was observed in the range of 1.5~1.8 M K 4 P 2 O 7 concentration, but current efficiency of about 100% was measured in the ranges of both 0.9~1.3 M and 2.1~2.4 M. The change of additive concentration did not influenced current efficiency. Residual stress of electrodeposited Cu thin films was measured to be about 20 MPa below 0.15 M Cu 2+ concentration and increased with the increase of it to 0.25 M. Maximum residual stress of 120 MPa was observed at 0.25 M Cu 2+ concentration. On the other hand, residual stress decreased from 80 to near 0 MPa as K 4 P 2 O 7 concentration varied from 0.9 to