Overview of Wafer Contamination and Defectivity

Chemical Mechanical Planarization-Related to Contaminants: Their Sources and Characteristics

“…In some cases, just two residual abrasives on the surfaces can make the device bad [9]. The particle larger than ½ the minimum feature size becomes a "killer defect" [39]. [3].…”

“…Heavy metals (Cu, Fe, Ni, Cr, Co, and Mo) that deposited on the wafer surface by the galvanic reaction can diffuse into the Si devices during heat treatments and cause excessive leakage currents, resulting in the device degradation and reliability problems [46]. Other metals (Al, group II metals, and Ti) may have much lower diffusivities and may not diffuse significantly into the Si devices [39]. Metal ions such as Cu, Co, Fe, Al, Zn, and Mg can hydrolyze in the alkaline based cleaning solution and form insoluble metal hydroxides that are remained on the wafer surfaces [15].…”

“…Cu electromigration occurs through the movement of Cu atoms or Cu ions when there is a strong electrical current [47]. The undesirable metallic particles can cause short circuits between metal lines, whereas the metal hydroxides may cause open circuits [39].…”

“…Mobile ions such as alkaline metals (Na + and K + ) originated from the slurry components such as salts and NaOH/KOH (pH adjuster) [18] (Table 2) can cause flatband shifts and surface-related leakage currents due to their electrical characteristics of high mobility [39]. Fe ions have been used as a catalyst for W CMP slurry [8].…”