Effect of Complexing Agents on Surface Composition for Co Post-CMP Cleaning Process

Abstract

The effect of surface composition change based on complexing agents on cobalt (Co) post-chemical mechanical polishing cleaning (cleaning) is investigated. The change in chemical composition of the Co surface significantly affects Co cleaning performance, as well as dissolution capacity of the complexing agent and pH of cleaning solution. Oxide composition of the Co surface was manipulated using different types of complexing agents. Addition of citric acid and glycine in cleaning solution resulted in predominant formation of Co3O4 and CoOOH on the Co surface, respectively. The citric acid-derived Co3O4 surface embraces abundant –O– terminates, which attracts the complexing agent and silica abrasive relatively weakly, resulting in suppression of recess formation and reduction of surface particle residue after cleaning. On the contrary, the –OH terminated CoOOH surface formed by glycine bound strongly with silica. Therefore, preferential development of Co3O4 on the surface considerably enhances Co cleaning performance, which is achieved by introducing citric acid in the cleaning solution. To sum up, we suggested an unconventional insight to understand the effect of Co surface chemical state on cleaning performance.

Tribo-Electrochemistry of Post-CMP Cleaning: Results for Co and Cu Wafer Films Brushed in Different Solutions

“…24 The pH setting of 11 for the CA solution was intended to operate within this domain, enabling the Co(OH) 2 makeup of any adsorbed surface species formed by OH − . The particular pH value of 11 has also been previously used for other CA based alkaline PCMPC solutions of Co 25,26 and Cu. 6 By maintaining the pH of the CA solution close to that of the CMP test slurry, it helped to avoid the introduction of significantly different surface chemistries in going from CMP to PCMPC.…”

“…The detailed solution chemistries, however, varied between the CMP and PCMP cases. 7 The strategy of maintaining mutually similar chemical environment between CMP and PCMPC processes has been used by other authors, 26 and this approach has been helpful for developing analytical PCMPC characterization protocols. 5 In the PCMPC setting, surface coverages of CMP residues should be substantially lower than those of the same species being generated in a CMP solution as primary materials for planarization.…”

Development of a pH-independent Post-CMP Cleaning Solution using Phosphoric Acid-based Surfactants for Removal of Ceria Nanoparticles

“…The chemical and mechanical planarization (CMP) and post-CMP cleaning technologies are advancing continuously with the decreasing size of the semiconductor integrated circuits and increasing the integration density. [1][2][3][4] During the process of semiconductor manufacturing, a significant amount of residues, such as photoresist, abrasive nanoparticles, and pad debris, are generated and unavoidably deposited on wafer surfaces. These materials, if not properly removed during cleaning, adversely affect the process yield and performances of semiconductor devices.…”