Experimental and theoretical investigation of the influence of carrageenan-polyvinyl pyrrolidone combination on the chemical mechanical polishing of TSV Ta barrier layers

Polishing of Ta barrier layer by through-silicon-via (TSV) has a low removal rate. Large particles with diameters greater than 0.5 μm tend to form in the slurry, which complicates the achievement of an atomic-level planarized wafer surface during chemical mechanical polishing (CMP) while also maintaining a high removal rate of Ta. To address this challenge, this paper developed a novel environmentally friendly surfactant for the Ta barrier layer polishing, composed of carrageenan (CG) and polyvinyl pyrrolidone (PVP). By contact angle measurement, electrochemistry, XPS, FESEM, slurry Zeta potential stability and particle size test, the synergistic mechanism of carrageenan and polyvinyl pyrrolidone was analyzed, and the comparative analysis of the surface quality of Cu and Ta was conducted after CMP under varying conditions. The findings reveal that slurry’s composition was modified by the addition of CG and PVP, the removal rate ratio of Ta to Cu achieves a 2:1 ratio under the conditions of 10 wt% SiO 2 , 0.3 wt% H 2 O 2 , 1.5 wt% guanidine phosphate (GP) and pH 9, surface roughness indicators, including Sq and Ra, of Cu and Ta both reach sub-nm level. The surface non-uniformity of Cu and Ta decreased to 1.7 % and 1.8 %. This indicates that the synergistic effect of CG and PVP in the slurry can obtain a better wafer surface while ensuring a high level of Ta removal efficiency.