New plating bath for electroless copper deposition on sputtered barrier layers

A new copper plating bath for electroless deposition directly on conductive copper-diffusion barrier layers has been developed. This plating bath can be operated at temperatures between 20 and 50 degrees C and has good stabil ity. High temperature processing allows for increased deposition rates and decreased specific resistivity values for the deposited copper films. Elect roless Cu films deposited from this bath showed a conformal step coverage i n high aspect ratio trenches and, therefore, are promising as seed layers f or copper electroplating. The effect of the bath composition, activation pr ocedure and processing temperature on the plating rate and morphology of th e deposited copper has been studied and is presented here. (C) 2000 Elsevie r Science B.V. All rights reserved.