This study investigated the wettability effect of polysilicon on the polishing performance and organic defect contamination during polysilicon chemical mechanical polishing ͑CMP͒. Contact angle measurement was utilized to understand the nature of polysilicon surfaces. An oxidizer, H 2 O 2 , was added to the silica slurry to modify a hydrophobic polysilicon surface to a hydrophilic surface during polishing. The adhesion force was measured between a polymeric pad particle and a poly-Si wafer surface in KOH solution ͑pH 11͒ as a function of H 2 O 2 concentration. The adhesion force of the polymeric pad particle on the polysilicon decreased from 14 to 8 nN as the peroxide concentration increased to 10 vol %, at which the surface became hydrophilic. The hydrophilization of the polysilicon surface during polishing drastically reduced the organic contamination on the polysilicon wafers after polishing. The removal rate, frictional force, and pad temperature during CMP, with and without oxidizing the surface, were measured. They all decreased with the increasing concentrations of the oxidizer. The decrease was attributed to the formation of the lubrication layer of the oxide surface due to the oxidation of polysilicon.Dynamic random access memory ͑DRAM͒ process technology has become a leading semiconductor technology, with the highest production volume among very large scale integration ͑VLSI͒ semiconductor products. The density of DRAM quadrupled approximately every three years by virtue of advances in DRAM technology. 1 Because of the decrease in device feature size, the chemical mechanical polishing ͑CMP͒ process has become a necessary processing step for planarizing the surfaces during the DRAM process. 2 Poly-Si CMP is implemented to reduce the step height of a gate poly-Si in the construction of a recess channel array transistor and Fin Field Effect Transistor ͑FinFET͒ three-dimensional structures. 3 Although the CMP process is performed effectually, there are several problems that need to be overcome, such as local dishing/erosion, scratches, and abrasive and organic particle contamination. 4 After the CMP process, the wafer surface might be contaminated by the abrasive particles and polymeric residues from the pad, the retainer ring, and other consumables. The removal of organic residues from the wafer surfaces is a great challenge for the next processing step. The surface of poly-Si is hydrophobic in nature. Hence, it attracts hydrophobic organic residues, mostly pad debris, during the CMP process. These organic defects are difficult to be removed by general post-CMP cleaning methods. 5-7 Because there is much concern about organic contamination on polished polysilicon surfaces after polishing, understanding the interaction between the organic residues and the polysilicon surface is required.Therefore, this study investigated the organic contamination mechanism of polymeric residues on polished polysilicon surfaces. H 2 O 2 , as an oxidizer, was added to the silica slurry to modify the wettability of the polysil...

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The adhesion and removal of the polymeric residues were investigated as a function of wettability of the poly Si surface during poly-Si CMP process. An oxidizer can make poly silicon surface more hydrophilic. Adhesion force between pad particle and poly Si wafer decreased and saturated as a function of concentration of oxidant. Much more pad particles with water marks were observed on hydrophobic poly silicon surfaces than on hydrophilic. The mechanism of wettability and high adhesion force of hydrophobic surfaces indicates that the controlling of the wettability of wafer surface played an important role in the adhesion and removal of organic residues on the poly Si surface. The control of poly silicon wettability during polishing could reduce the attraction force of organic particles thus lead to a lower organic defects after CMP.

Heavily doped poly silicon films have been widely used as gate electrodes and interconnection in MOS circuits. The shrinkage of devices below 100 nm requires more stringent and new CMP processes including poly silicon CMP. Poly silicon can be polished easily with similar pads and slurries as they are used for the planarization of silicon oxide. In this study, single crystal and poly silicon wafers were polished as a function of pH in fumed silica based slurry to understand and compare the polishing mechanism of silicon. The static and dynamic etch rates and polishing temperature were measured as a function of slurry pH (11 ~ 13) with friction forces. The single crystal silicon (bare silicon) showed higher removal rate than poly silicon. However, higher friction force was measured on poly silicon wafer than on bare wafer. The initial wettability of poly silicon with HF and without HF was treatment.