ATOMIC-SCALE REMOVAL MECHANISM DURING Si TIP SCRATCHING ON Si AND SiO2 SURFACES IN AQUEOUS KOH WITH AN ATOMIC FORCE MICROSCOPE

The atomic-scale removal mechanism during Si tip scratching on Si wafer or SiO2 film in aqueous KOH has been examined using an AFM. Authors found that the Si tip removal volume in moles was in agreement with that of the corresponding Si or SiO2 specimen. This equality implies that the process begins with formation of the Si-O-Si bridge between one Si atom of the tip and one Si atom or one SiO2 molecule of the specimen at the wear interface, followed by the local oxidation of the Si surface, and finally the bond rupture by the tip movement, the dimeric SiO2 (OH)3Si-O-Si(OH)3, including the Si-O-Si bridge is dissolved in the KOH solution. Comparison of the wear behavior of Si and SiO2 shows that they are almost the same, indicating that a similar reaction would occur due to the local development of oxide nuclei on the Si surface. 24 refs.