Creation of Reactive Micro Patterns on Silicon by Scanning Electrochemical Microscopy

A chemical route to locally etch the native silica film on silicon, using the SECM, thus creating patterns of reactive Si-H holes, is described. The procedure is based on the alteration of the pH in the volume between the SECM tip and the pristine p-Si substrate so as to turn locally the initially inert fluoride solution into a strong etchant capable to bear holes through the SiO(2) native layer in a very controlled and highly reproducible way. The direct electrochemical grafting of p-NO(2)-benzene diazonium cation into the etched Si-H holes and the subsequent functionalization of the electrografted organic layer by either a fluorescent probe or a redox probe (HRP) were then used to highlight the versatility of this approach for the fabrication of micropatterned functional surfaces.