Chemical mechanical planarization (CMP) is a triboelectrochemical process dominated by mechanical and chemical-assisted wear. The choice of abrasive used in this process is of fundamental importance. In this study, oxide CMP using novel polymer-core silica-shell composites were compared with conventional colloidal silica as abrasives in terms of removal rate and surface finishing. The composite particles were achieved by either creating chemical bonds by silane coupling agents or tuning the pH to form electrostatic attractive interactions between the core and the shell. We used oxide CMP as a convenient test vehicle for defectivity characterization and comparison between different abrasives. Due to the higher complexity of the composite abrasive with respect to the simple silica particle-wafer system, we combined different surface analysis techniques with methods of defect quantification and enhancement. Overall, fewer and shallower scratches were detected for the composites with respect to colloidal silica.

The results of copper chemical mechanical planarization (CMP) experiments with a model slurry chemistry based on the combination of glycine–water–benzotriazole <mml:math display="inline"><mml:mrow><mml:mo>(</mml:mo><mml:mi>Gly</mml:mi><mml:mo>–</mml:mo><mml:msub><mml:mi mathvariant="normal">H</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mo>–</mml:mo><mml:mi>BTA</mml:mi><mml:mo>)</mml:mo></mml:mrow></mml:math>(Gly–H2O2–BTA) , and different types of composite A (silane coupling agents between the polymer core and the silica shell) and B (electrostatic attraction between the polymer core and the silica shell) abrasives, are presented. While the presence of BTA allows a 10-fold reduction in the static etch rate from <mml:math display="inline"><mml:mrow><mml:mn>95</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mtext>to</mml:mtext><mml:mspace width="0.3em"></mml:mspace><mml:mn>10</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mi>nm</mml:mi><mml:mo>∕</mml:mo><mml:mi>min</mml:mi></mml:mrow></mml:math>95to10nm∕min , combining an oxidizer and complexing agent leads to removal rates higher than <mml:math display="inline"><mml:mrow><mml:mn>400</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mi>nm</mml:mi><mml:mo>∕</mml:mo><mml:mi>min</mml:mi></mml:mrow></mml:math>400nm∕min . Different surface morphology and root-mean-square (rms) roughness are observed after polishing with composite abrasives combined with different peroxide concentrations. Oxidizer concentrations as low as <mml:math display="inline"><mml:mrow><mml:mn>0.1</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mi>vol</mml:mi><mml:mspace width="0.3em"></mml:mspace><mml:mo>%</mml:mo></mml:mrow></mml:math>0.1vol% lead to a high nonuniformity and defectivity values. In particular, at pH <mml:math display="inline"><mml:mrow><mml:mo>∼</mml:mo><mml:mn>6</mml:mn></mml:mrow></mml:math>∼6 , composite B performs better than pure colloidal silica during copper CMP using the IC-1000 pad, giving a comparable material removal rate (MRR), but a better surface finish due to the contribution of the elasticity of the polymer in gently transferring the applied load to the wafer surface. Cu CMP with pure polymer particles is a promising alternative to the hard inorganic material, especially if combined with suitable surfactants that act from both particle stabilization and friction reduction/lubrication improvement perspectives. The use of a medium/high-hardness pad IC-1000 is compared to the use of a soft Politex pad. In the former case, differences in terms of MRR, rms roughness, and total defects are observed between the composite abrasives A and B; in the latter case, the behavior of the two composites is similar. In the case of a soft pad in combination with composite abrasives, there is a remarkable improvement in the defectivity without any loss in MRR.

The results of a wet alkaline seed deposition process directly on a thin adhesion promoter film, such as chemical vapor deposition (CVD) Co, are presented. This solution has been successfully used for copper plating on blanket and patterned through-silicon-via (TSVs) wafers covered with either silicon oxide/physical vapor deposition (PVD) Ta/CVD Co or silicon oxide/PVD Ti/CVD Co stacks. Such direct plated films were used as seed layers for subsequent copper plating from an in-house-made acidic Cu bath with model additives poly(ethylene glycol) (PEG), bis(3-sulfopropyl) disulfide (SPS), and Janus Green B (JGB). We report the impact of the directly plated stack composition and thicknesses on the integration of the wet alkaline seed in TSVs with <mml:math display="inline"><mml:mrow><mml:mn>5</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mi>μ</mml:mi><mml:mi mathvariant="normal">m</mml:mi></mml:mrow></mml:math>5μm width and high aspect ratio (HAR) as high as 8:1. The conformal wet seed layer enables the achievement of a successful void-free filling using an in-house made acidic Cu bath with model additives (SPS, PEG, and JGB).

The continuation of CMOS scaling leads to the necessity of replacing Cu as an interconnect material with a metal with lower resistivity and better reliability performance. At the same time, significant technological improvements are required to mitigate the pattern overlay requirements when forming multilevel structures with a half-pitch below 10 nm. Area-selective deposition (ASD) offers an elegant way to enable self-alignment of multilevel structures. However, defectivity is a typical bottleneck of ASD integration. This work explores the selective electroless deposition (ELD) of Co as a replacement of Cu as an interconnect metal. The selective metallization process is promoted by the selective placement of an amino-terminated organic layer in combination with confined grafting of a Pd catalyst. Co films thicker than 40 nm can be formed on amino-terminated surfaces, while the surfaces with no amino functionality remain completely free of Pd and Co according to EDS chemical analysis and SEM inspection. This article offers a detailed study of selective Co growth on blanket and patterned structures and investigation of the ELD Co film properties, such as low-temperature recrystallization at 420 °C, grain structure, chemical composition and segregation of impurities. It is demonstrated that the resistivity of the ELD Co films exhibits lower thickness dependence when compared to that of PVD Co, which can be attributed to the ELD Co grain size exceeding the Co film thickness. In addition, it is shown that the underlying organic layer prevents the silicidation of the annealed Co film on the Si substrate while promoting interface adhesion values as high as 8.2 J m⁻² ± 0.7 J m⁻² for a 50-nm thick Co film.