The role of ammonium citrate and dodecyl pyridinium chloride on chemical mechanical polishing relevant to SiO2 dielectric layer

Abstract

Silicon dioxide films are widely utilized in integrated circuit manufacturing for their excellent properties, including applications in shallow trench isolation and interlayer dielectrics. Chemical mechanical polishing (CMP) has a pivotal part in achieving material planarization across integrated circuit manufacturing process. This study delves into the mechanisms of ammonium citrate and dodecyl pyridinium chloride in the CMP of silicon dioxide dielectric layers, alongside optimizing the concentration ratios of the slurry components. The incorporation of ammonium citrate effectively mitigates electrostatic repulsion between the abrasive and the wafer surface, thereby augmenting the mechanical interactions during polishing. The introduction of dodecyl pyridinium chloride further enhances material removal rates while concurrently reducing surface roughness. Notably, employing the slurry with the optimized composition ratios yields a notable reduction in surface defects after CMP. Extensive characterization techniques, including X-ray photoelectron spectroscopy and scanning electron microscope, were devoted to elucidate the mechanisms of the additives and assess the stability of the slurry. This study substantiates that the incorporation of ammonium citrate and dodecyl pyridinium chloride in the slurry not only sustains a high material removal rate but also achieves superior outcomes in terms of lower wafer surface roughness and diminished wafer surface defects.