Copper dual damascene is becoming the standard process for sub-quarter micron microelectronic interconnects. Photo-induced anodic corrosion could occur on a copper p-n junction sctructure during PCMP cleaning process and the prevention of such corrosion is critical for reducing defects and improving overall yield of copper integration. The electron/hole pairs are photo-generated in the p-n junction inducing potential difference. p+ diffused region has a built-in potential of 0.2~0.5 volts against n+ diffused region. Therefore, copper oxidation and etching happen on the p-side and copper re-deposition and growth are shown on the n-side. Tafel curve measurements can be used to provide accelerated corrosion rate data at certain voltage biases that can be charateristic of copper anodic corrosion. From the PCMP cleaning chemistry perspective, increasing copper inhibitor concentration and/or decreasing copper chelator levels are found to protect copper from anodic corrosion at voltage bias. In addition, using additional additives in the PCMP process can further reduce copper anodic corrosion in a PCMP environment.
In the copper CMP process, organic residues that are related to Benzotriazole (BTA) adsorbed on copper surface after Cu CMP process have to be removed during the cleaning. In order to address this organic defect issue, we present here the study of the performance of BTA removal by post-CMP cleaners using copper particles as substrates instead of copper wafers. In this work, different copper particles including Cu(0), Cu(I) and Cu(II) oxide particles with high surface area, were chosen to study the removal of BTA adsorbed on different copper states. TGA and UV-Vis spectra were used to detect and quantify the BTA removal efficiency. The results by different post CMP cleaners on various Cu particles will be presented.
High Productivity Combinatorial (HPC) technology was used to evaluate post-CMP clean chemistries and their impact on copper surface corrosion protection and queue time performance. Cleaning formulations at low pH and high pH, both with and without functional additives, were used to produce a wide range of surface conditions typical in semiconductor processing. X-ray photoelectron spectroscopy (XPS) results show that low pH cleans remove most oxides, but that within 20 hrs copper oxide re-growth occurs in the form of Cu (I) and Cu (II) oxide species. Electrochemical analysis is a simpler and higher throughput method to study oxide growth over time. Good agreement existed between electrochemical and XPS techniques when both were used to study copper surfaces for 0 to 20 hours after clean. The electrochemical tests were continued after 48 hours of queue time to develop a better understanding of oxide growth trends, and showing continued oxidation of Cu surfaces treated with low pH cleans. For extremely long queue times, SEM analysis shows growth of visible copper oxide nodules on Cu lines and pads for low pH treated M1 test structures. Leakage of comb structures monitored as a function of queue time was inconsistent, indicating that standard leakage measurements at 1V for comb structures with 0.125 / 0.175 line/space dimensions are not sensitive to the copper surface instability of oxidation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.