ScholarWorks@중앙대학교

초록

With the apparent miniaturization trends in interconnection materials, cobalt (Co) is emerging as a promising interconnect metal. This study suggests persulfate chemicals - ammonium persulfate (APS), potassium persulfate (KPS), and sodium persulfate (SPS) - as alternative oxidizers to address the aging issue of traditional hydrogen peroxide (H2O2)-based slurries and evaluates the suitability for use in Co CMP slurries. Due to their higher standard reduction potential than H2O2 ions, persulfate ions oxidize the Co surface, effectively oxidize the Co surface, increasing the removal rate (RR). APS, in particular, facilitates the formation of Co(III) ions, leading to the oxidation of Co3O4. Co3O4 is a stable passivation layer that prevents unintended surface corrosion. Co(III) ions formed by APS promote the formation of a more stable Co-EDTA complex, resulting in both a higher removal rate (RR) and a lower static etch rate (SER). The zeta potentials of NH4+ and silica abrasive were also discussed, which enhanced the interaction between the abrasive particles and the Co surface. Persulfate chemicals correlate well with BTA by absorbing and forming a stable Co-BTA passivation layer. Through this study, persulfate materials, particularly APS, demonstrated superiority as oxidizers for Co CMP slurries, thus providing the foundation for next-generation interconnection materials.

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