AFM investigations of chemical-mechanical processes on silicon(100) surfaces

Abstract

ABSTRACTAtomic force microscopy (AFM) was used to examine chemical-mechanical processes on Si (100) surfaces. Places where the underlying silicon was exposed etched in basic solution, producing structures 100 nm or less in size. Etching occurs only in the presence of combined mechanical and chemical effects. By performing AFM in basic solution, the entire etching process could be observed directly. High-force scans were used to remove oxide and initiate etching in selected locations, followed by low-force scans which imaged the etching process. Although roughness initially increased during etching, the final surfaces were smooth. The etching was measured for different applied loads, numbers of scans, concentrations of the etching solution, and time. The oxide layer was extremely sensitive to applied stress, and even very light scanning caused the oxide layer to dissolve more rapidly. Once the oxide layer was removed, chemical etching proceeded with or without AFM scanning, but if AFM scanning was continued additional material was removed, probably by a tribochemical mechanism on pure Si.