Study on Amino Acid Corrosion Inhibitors in Tungsten Chemical Mechanical Planarization

Abstract Addition of corrosion inhibitor in the slurry during tungsten (W) chemical mechanical planarization (CMP) process is an effective way to avoid excessive corrosion. In this work, three environmentally friendly amino acids (lysine, leucine, and glutamic acid) were chosen as corrosion inhibitor during W CMP process. A smooth wafer surface was obtained after CMP with the addition of lysine. The static etching rate of the W film decreased from 45.9 Å/min to 7.1 Å/min while an excellent wafer surface roughness (Ra=1.267 nm) was obtained with the addition of 0.25 mmol/L lysine. The results indicate that increasing the amount of protonated amino acid molecules in the slurry can result in the improvement of corrosion inhibition performance as well as decrease the material removal rate. Electrochemical tests indicated that the corrosion inhibition effect can be attributed to the formation of an amino acids adsorption layer on the wafer surface, inhibiting the formation of peroxotungstic acids by the interaction between H2O2 and W film in the concave region. This work provides valuable guidance for the application of environmentally friendly amino acid corrosion inhibitor in the CMP field.