Effects of oxidizing agent and hydrodynamic condition on copper dissolution in chemical mechanical polishing electrolytes

The effects of H2O2 and Fe(NO3)3 on the electrochemical behavior, dissolution rate and surface characteristics of Cu in static and under rotating conditions were investigated. Rotating cylinder electrodes were used for potentiodynamic polarization curves measurements in 0.0078 Mcitric acid (CA) base electrolytes with various concentration ofH2O2 (0–12 vol.%) and Fe(NO3)3 (0– 0.2 M). The rotating speed was varied in the range of 0–3000 rpm. The dissolution rates of Cu were determined using Tafel extrapolation, inductively coupled plasma-mass spectrometry (ICP) solution analysis, and weight loss measurements, depending on the electrolytes involved. The surfaces of specimens after immersion in the electrolytes for a certain period of time were characterized with Auger electron spectroscopy (AES), X-ray photo-electron spectroscopy (XPS), and atomic force microscopy (AFM). The experimental results showed that H2O2 with sufficient concentration could promote passivation of Cu in the CA base electrolyte, which was confirmed by AES and XPS. The addition of Fe(NO3)3 into the CA base electrolyte did not cause the formation of passive film and its presence enhanced the dissolution rate of Cu. In both H2O2 and Fe(NO3)3 containing electrolyte, the dissolution rates increased with increasing electrode rotating speed. # 2004 Elsevier B.V. All rights reserved