No abstract

For the copper (Cu) chemical mechanical polishing (CMP) of integrated circuit Cu wiring, the removal rate (RR) in the concave is lower because of the protecting of inhibitor in the slurry, and the step height is reduced by the high RR different between convex and concave, thus realizing planarization. With the decrease of technology node and the shortcomings of traditional inhibitors, new environmental inhibitors have become the focus of research. The synergistic inhibiting effect of ammonium dodecyl sulfate (ADS) and 1,2,4-triazole (TAZ) in the H2O2 based weakly alkaline slurry during the Cu film CMP process was studied. Electrochemistry, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) measurements were used to analyze the reaction mechanism between Cu and mixed inhibitors. It was found that ADS was absorbed on the Cu surface via electrostatic interactions, by which a thin porous film with small openings was formed. Then chemisorbed TAZ molecules effectively filled up the small openings, and a compact passivating film was formed to protect the Cu surface. Based on the background slurry, incorporation of 0.1 wt% ADS + 0.003 wt% TAZ (bulk) and 0.1 wt% ADS + 0.005 wt% TAZ (soft landing) at pH = 8.5 in this slurry, lower step height was achieved dropping from the initial 3800 Å to 654 Å, and the slurry can be stable for at least three days. Such results indicate that mixed inhibitors may become a trend of industrial application, and such research has certain guiding significance for industrial production.

Sapphire with different crystal planes is widely used in light-emitting diode (LED), silicon on sapphire (SOS) IC chips, hybrid microelectronic applications, and other high-tech fields. Chemical mechanical polishing (CMP) technology is widely applied to obtain super-smooth and non-damaged wafer surface on the sapphire wafer. Due to its higher hardness and brittleness, sapphire CMP processing is difficult because of its lower processing efficiency. In this paper, in order to improve the CMP performance of different plane sapphire, K2S2O8 was used as an additive in the slurry. On the basics of chemical thermodynamic theory, HSC(enthalpy (H), entropy(S), heat capacity (C)) chemistry software was used to judge whether the chemical reactions can occur spontaneously. According to the experiment results, a higher material removal rate (MRR) was obtained with the slurry containing 0.2 wt% K2S2O8 and the surface roughness Sq of different plane sapphire substrates were all less than 0.3 nm. At the same time, the reaction mechanism and process of K2S2O8 was revealed. X-ray photoelectron spectroscopy (XPS) analysis showed that there were new chemical reactions between the sapphire wafer and K2S2O8 sol and the reaction products included aluminum sulfate (Al2(SO4)3) and potassium sulfate (K2SO4), which increased the chemical effect during the polishing process and resulted in the increasing of MRR.