Effect of the Etching on Chemical Mechanical Planarization of the Selective Layer Surface

Abstract

Among other the planarization technologies, Chemical mechanical planarization (CMP) is the unique global planarization technology, which makes it be continuously investigated. The planarization (polishing) and micromachining are of considerable interest to different engineering fields, such as the friction couples that function with the selective transfer and is used to remove excess of metal, obtained in process of selective transfer and for the understanding of planarization and micromachining. For an effective planarization, it is necessary to minimize the surface defects while attaining a good planarity with optimal material removal rate (MRR). These requirements can be met by controlling the chemical and mechanical interactions during the polishing process, or by engineering the slurry chemistry, particles properties, and stability. Effect of the etching during CMP process of the selective layer surface are presented in this paper. To optimize the process of selective layer CMP a blanket selective layer samples were polished with, colloidal silica-based slurry which contains a citric acid and an oxidizer (H 2 O 2 ). Surface studies using X-ray photoelectron spectroscopy (XPS) were performed on selective layer samples after chemical etching in order to determine the effect that different polishing parameters (i.e., pH and H 2 O 2 concentration) have on the selective layer surface. Then, the samples were passively soaked in an acidic slurry mixture containing different concentrations of H 2 O 2 to determine how the chemical action alone affects the removal of the selective layer. The etching results revealed that a cuprous oxide (Cu 2 O) forms on the surface of the etched metallic selective layer while polished samples showed CuO and Cu(OH) 2 . The effect of these selective layer oxide films on the removal of the selective layer in passive etching and CMP is discussed.

The Effects of Friction and Temperature in the Chemical–Mechanical Planarization Process

“…To this, the applied force calculation during planarization on a single abrasive was necessary [ 7 ]. This was possible by determining the contact area resulting from the applied pressure between the pad and the nanoparticle by the pad’s head [ 16 ], which is consistent with the modeling from previous studies [ 12 , 18 , 25 , 28 ]. Hence, it is possible for the MRR to be controlled by the lubrication effect introduced by the surfactant through the friction forces between the wafer and the abrasive nanoparticles.…”

“…Therefore, during the friction process in the CMP, the change in the CMP process temperature becomes essential. The effects of the slurry nanoparticle concentration and size were investigated by many researchers [ 16 , 24 , 25 , 26 ], often with contradictory results, because it influences the MRR during the CMP process.…”

“…In-depth studies by simulation with AFM on the friction in situ between single-particle and the substrate in suspension with a surfactant highlighted the response of friction force. These simulations demonstrated that the slurry chemistry, including the composition, pH, and adhesion tension of the surfactant, could be adjusted to ensure the necessary friction force for optimal planarization performance [ 25 , 30 ]. A certain surface-active surfactant has an optimum concentration range, which ensures that the dispersion ability results in a better surface quality.…”