Surface chemistry studies of the chemical mechanical planarization (CMP) of copper are presented in this paper. Blanket copper samples were polished with an acidic alumina-based slurry which contains an organic acid salt (phthalic acid salt) and an oxidizer false(H2O2false). Surface studies using X-ray photoelectron spectroscopy (XPS) were performed on copper samples after chemical etching or CMP in order to determine the effect that different polishing parameters (i.e., pH and oxidizer concentration) have on the copper surface. XPS studies were also done on samples that were passively soaked in an acidic slurry mixture containing different concentrations of H2O2 to determine how the chemical action alone affects the removal of copper. The etching results revealed that a cuprous oxide false(Cu2Ofalse) forms on the surface of etched metal while polished samples showed CuO and normalCufalse(OH)2. The effect of these copper oxide films on the removal of copper in passive etching and chemical mechanical polishing is discussed. © 2001 The Electrochemical Society. All rights reserved.

We describe the chemical mechanical planarization (CMP) of copper damascene structures using an IC1400 pad and four different types of slurries. Two alumina-based slurries and two silica-based slurries were evaluated. After successful removal of the excess Cu, we examined the topography of the planarized structures using scanning electron microscopy. The effects of the CMP process on spacer erosion, Cu line recess, corrosion of submicrometer Cu lines, liner removal selectivity, and contamination of the patterned structures are presented. It was found that minimizing the etch rate (ϳ10 nm/min) of the slurry is required to achieve reproducible removal rates and unrecessed (etched) damascene structures. No dishing was observed with the utilized pad. We also show that corrosion is prone to occur in low Cu pattern density areas and that the removal of the liner material (tantalum) remains problematic because of its chemical inertness.

We describe chemical mechanical polishing (CMP) of blanket and patterned aluminum films employing a polyurethane pad and a slurry based on alumina particles as the abrasive and hydrogen peroxide as the oxidizer. The experiments were conducted at pressures from 19 to 47 kPa and at linear velocities from 26 to 48 m/min, and yielded Al removal rates from 80 to 250 nm/min. The oxidant concentration has a weak effect on the removal rate of Al. Polishing selectivities of Al to silicon dioxide as high as 130:1 were obtained with the maximum selectivities being observed at regions of low pressures and low velocities. The Preston equation fails to describe the dependence of the removal rate on pressure and velocity, and a power function is proposed instead. X-ray photoelectron spectroscopy was used to examine the surface of Al before and immediately after CMP. These experiments provided information on the thickness of the oxidized Al layer. We found that larger removal rates correlated with a smaller Al-oxide thickness.