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 (C ₆H ₅N ₂BF ₄). Scratching activates the silicon surface by removing the passivation oxide layer to expose fresh Si atoms. The surface morphologies before and after chemomechanical reaction are characterized with atomic force microscopy. Time-of-flight secondary ion mass spectroscopy confirms the presence of C ₆H ₅ 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 C ₆H ₅N ₂BF ₄.C ₆H ₅ 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 C ₆H ₅ groups from aryldiazonium salt. The relevant 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 systems components under different environments and operating conditions.