Effects of Pd activation on the self annealing of electroless copper deposition using Co(II)–ethylenediamine as a reducing agent

Abstract

We investigated the effect of Pd activation on self-annealing in electroless Cu deposits using Co(II)–ethylenediamine as a reducing agent. The size and population of Pd particles were controlled by Pd ion concentration and activation time, which resulted in changes in the sheet resistances. While the low population of Pd particles (<109cm−2) was unable to create completely continuous Cu film in subsequent electroless deposition and induced high film resistivity due to the voids, Pd particles that were over 20nm in diameter increased the resistivity by raising the surface roughness of the Cu film. The optimal Pd activation condition was with Pd particle density of 1.73×109cm−2 with 14nm diameters. The resistivity of the Cu film in the optimal activation condition decreased to 2.46μΩcm. The deposited Cu film showed a low resistivity and a strong Cu (111) texture with the decrease in size and increase in the number of the Pd particles.