Effect of ethylenediamine on CMP performance of ruthenium in H2O2-based slurries

Triple Synergism Effect of Ammonium Nitrilotriacetate on the Chemical Mechanical Polishing Performance of Ruthenium Barrier Layers

As the feature size of integrated circuits continues to decrease, ruthenium (Ru) has been suggested as the successor to traditional Ta/TaN bilayers for barrier layer materials due to its unique properties. This research delves into the effects of ammonium nitrilotriacetate (NTA(NH4)3) on the chemical mechanical polishing (CMP) performance of Ru in H2O2-based slurry. The removal rate (RR) of Ru surged from 47 to 890 Å min-1, marking an increase of about 17 times. The essence of this mechanism lies in the triple synergistic effects of NTA(NH4)3 in promoting ruthenium (Ru) removal: 1) The interaction betweenNH 4 + ${\mathrm{NH}}_{\mathrm{4}}^{\mathrm{+}}$ from NTA(NH4)3 and SiO2 abrasives; 2) The chelating action of [(NH4)N(CH2COO)3]2- from NTA(NH4)3 on Ru and its oxides; 3) The ammoniation and chelation of Ru and its oxides byNH 4 + ${\mathrm{NH}}_{\mathrm{4}}^{\mathrm{+}}$ from NTA(NH4)3, which enhance the dissolution and corrosion of oxidized Ru, making its removal during the barrier layer CMP process more efficient through mechanical means. This research introduces a synergistic approach for the effective removal of Ru, shedding light on potential applications of CMP in the field of the integrated circuits.

Materials Quest for Advanced Interconnect Metallization in Integrated Circuits

Integrated circuits (ICs) are challenged to deliver historically anticipated performance improvements while increasing the cost and complexity of the technology with each generation. Front-end-of-line (FEOL) processes have provided various solutions to this predicament, whereas the back-end-of-line (BEOL) processes have taken a step back. With continuous IC scaling, the speed of the entire chip has reached a point where its performance is determined by the performance of the interconnect that bridges billions of transistors and other devices. Consequently, the demand for advanced interconnect metallization rises again, and various aspects must be considered. This review explores the quest for new materials for successfully routing nanoscale interconnects. The challenges in the interconnect structures as physical dimensions shrink are first explored. Then, various problem-solving options are considered based on the properties of materials. New materials are also introduced for barriers, such as 2D materials, self-assembled molecular layers, high-entropy alloys, and conductors, such as Co and Ru, intermetallic compounds, and MAX phases. The comprehensive discussion of each material includes state-of-the-art studies ranging from the characteristics of materials by theoretical calculation to process applications to the current interconnect structures. This review intends to provide a materials-based implementation strategy to bridge the gap between academia and industry.