Preparation of Aryldiazonium Salt Monolayers on Si(100) Surface by Chemomechanical Method

Functionalizing and patterning of the silicon surface can be realized simultaneously by the chemomechanical method. The oxide-coated crystalline silicon (100) surface is scratched with a diamond tool in the presence of aryldiazonium salt (C₆H₅N₂BF₄). Scratching activates the silicon surface by removing the passivation oxide layer to expose fresh Si atoms. The sur-face morphologies before and after chemomechanical reaction are characterized with atomic force microscopy. Time-of-flight secondary ion mass spectroscopy confirms the presence of C₆H₅ and provides evidence for the formation of self-assembled monolayer (SAM) on silicon surface via Si-C covalent bonds by scratching the silicon in the presence of C₆H₅N₂BF₄. C₆H₅ groups further bond with surface Si atoms via Si-C covalent bonds as confirmed from infrared spectroscopy results. We propose that chemomechanical reaction, which occurred during scratching the silicon surface, produce C₆H₅ groups from aryldiazonium salt. The rel-evant adhesion of SAM is measured. It is found that SAM can reduce the adhesion of silicon. The monolayer can be used as anti-adhesion monolayer for micro/nanoelectromechanical sys-tems components under different environments and operating conditions.