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Chemical mechanical planarization (CMP) is recognized to be one of the finest polishing techniques which provides a smooth and globally planarized metal surface in the field of semiconductor device manufacturing. This process aids in material removal followed with a well finished and planarized surface by a combination of both chemical and mechanical action imparted by oxidizer and abrasive particle respectively. Semiconductor device manufacturing process is an amalgamation of two sub processes i.e. front end of line (FEOL) and back end of line (BEOL). The whole process consists of different segments comprising of several types of material that need to be planarized. The slurry components play an imperative role in metal CMP. It comprises abrasive, oxidizer, and several additives such as complexing agent, corrosion inhibitor, pH adjustor, slurry stabilizer, etc. and each imparts diverse impact on the material needs to be polished. One of the main topics of concern in this area is the removal rate selectivity of interconnects metal to the barrier layer metal. Thus, the reported review work efforts to emphasize the planarization of barrier layer materials, the various key ingredients employed in metal CMP and removal rate selectivity between interconnects and barrier layer metal.

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This work reports urea as a promising complexing agent in sodium carbonate (Na2CO3) based alumina slurry for chemical mechanical planarization (CMP) of tantalum (Ta) and copper (Cu). Ta and Cu were polished using Na2CO3 (1 wt.%) with alumina (2 wt.%) in the presence and absence of urea. The effect of slurry pH, urea concentration, applied downward pressure and platen rotational speed were deliberated and the outcomes were conveyed. Prior to the addition of urea, Ta removal rate (RR) was observed to enhance with pH from acidic to alkaline having maximum RR at pH 11. However, Cu RR decreases with increasing pH with minimum RR at pH 11. With the addition of urea in the slurry, Cu to Ta removal rate selectivity of nearly 1:1 is encountered at pH 11. The addition of urea boosts the Ta RR and suppresses Cu RR at the same time at 11 pH, as it adsorbs on the metal surface. Potentiodynamic polarization was conducted to determine the corrosion current (Icorr) and the corrosion potential (Ecorr). The electrochemical impedance spectroscopy (EIS) of both the metals was carried out in the proposed formulation and the obtained outcomes were elaborated.

This study investigates sodium carbonate and potassium carbonate as oxidizers for copper (Cu) chemical mechanical planarization (CMP). The dissolution study was conducted to estimate etch rate (ER) in the entire odd pH range for both the suggested oxidizers. The etch rate decreases as the pH increases from acidic to alkaline region. The effect of change in temperature of the working solution on Cu dissolution is also investigated. Based on the experiment conducted and the values obtained, the enthalpy (ΔHact) and entropy (ΔSact) of both the system were calculated. The contact angle was measured to further examine the surficial synergy between the oxidizers and the exposed Cu surface.