Study of Sintering Behavior of Vapor Forms of 1-Octanethiol Coated Copper Nanoparticles for Application to Ink-Jet Printing Technology

Sub-50 nm copper nanoparticles coated with sub-5 nm 1-octanethiol layer for oxidation inhibition were examined to confirm the 1-octanethiol removal temperature as the sub-50 nm copper nanoparticles are sintered. As a result, 1-octanethiol Self-Assembled Multi-layers (SAMs) on sub-50 nm copper nanoparticles were successfully removed before sintering of copper nanoparticles so that a high density of copper line could be obtained. Finally, the line resistivity was measured and compared to verify the effect of sintering in different atmospheres. As a result, electrical resistivity of the copper pattern sintered in hydrogen atmosphere was measured at 6.96 x 10(-6) ohm-cm whereas that of the copper pattern sintered in mixed gas atmosphere was measured at 2.62 x 10(-5) ohm-cm. Thus, sintering of copper patterns was successfully done to show low electrical resistivity values. Moreover, removal of 1-octanethiol coating after sintering process was confirmed using X-ray photoelectron spectroscopy (XPS) analysis. By showing no sulfur content, XPS results indicate that 1-octanethiol is completely removed. Therefore, the vapor form of 1-octanethiol coating layers can be safely used as an oxidation inhibition layer for low temperature sintering processes and ink-jet applications.This work was supported by the Ministry of Commerce Industry and Energy (MOCIE) project number 100-300-38, by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and technology. (2011-0027380), and Human Resource Development of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Ministry of Knowledge Economy, Republic of Korea (No. 2010-4010100620). The authors would like to thank Gi-Ra Yi at Chungbuk National University for his support