Regulating Molybdenum Dissolution through Controlled Oxide Phase Formation in CMP with Catalytic Oxidation

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Molybdenum (Mo) is a promising candidate for replacing tungsten in next-generation semiconductor processes due to its lower electrical resistivity and superior gap-filling capabilities. Despite its properties, the high dissolution of Mo during chemical mechanical planarization (CMP) leads to surface deterioration and device failure, limiting its practical application.Mo CMP, like other metal CMP, uses hydrogen peroxide (H2O2) to form and then remove metal oxide layers. However, H2O2 is a strong oxidant at a commonly used pH, and thus soluble Mo (Ⅵ) oxide (i.e., MoO3) formation cannot be avoided. One of Mo's oxides, MoO3, has a solubility of 4.9-70 g/L at room temperature, and Mo film reacts with H2O2 to form it in a chain. Excessive oxidation of Mo results in defects such as Mo dissolution and local corrosion during the CMP process, affecting the performance and reliability of the device.We control the formation of Mo oxide phases, affecting the dissolution properties of Mo, by modulating the activity of the oxidant and catalyst. Catalytic oxidation with Fe ion catalyst and H2O2 oxidant promotes the formation of the insoluble MoO2 and Mo2O5 phases while reducing the formation of the soluble MoO3 phase. With catalytic oxidation facilitated by Fe ions, during CMP, the removal rate of Mo increased from 780 to 1500 Å/min, and the dissolution rate decreased from 636 to 57 Å/min. In addition, surface roughness (Rq) also decreased from 3.38 to 0.35 nm. These results indicate that the improvement in Mo CMP performances could be achieved by employing Fe ions in catalytic oxidation.