Photopatterning of gold and copper surfaces by using self-assembled monolayers

A photolithographic technique was successfully employed to generate micropatterns of gold and copper by using self-assembled monolayer (SAMs) as resist materials. Copper patterns were successfully prepared from SAMs of 11-mercaptoundecanoic acid (MUA) and dodecanethiol (DDT) on Cu after UV irradiation followed by etching but gold patterns were prepared only from the SAM of MUA and not from the SAM of DDT, which revealed the difference of photooxidation of the metal–sulfur bond on SAMs. However, the maximum resolution of the pattern was about 1.0 μm on gold and 5.0 μm on copper. This may be due to lower quality packing of SAM on copper than gold. Ellipsometric and cyclovoltammetric observation of SAMs during the UV irradiation indicated the gradual removal of SAMs on copper and gold. Photopatterning of gold and copper by using SAM is more compatible with the current microelectronics process and is complementary to the microcontact printing technique.