Akihiko Saguchi

AFM Studies on the Difference in Wear Behavior Between Si and SiO2 in KOH Solution

Wear behavior between a Si tip and a SiO 2 film in KOH solution at various pH values has been examined by using an atomic force microscope We found that the Si tip removal amount strongly depended on the solution pH value and was at a maximum at pH 10.2-12.5 This result indicates that wear behavior of the Si tip is similar to that of actual chemical mechanical polishing of a Si wafer It was also found that the Si removal volume in moles was approximately equal to that of SiO 2 irrespective of the solution pH value This equality implies that a Si-O-Si bridge is formed between one Si atom and one SiO 2 molecule at the wear interface, followed by the oxidation of the Si tip, and finally the bond rupture by the tip movement and the silica species including the Si-O-Si bridge is dissolved in the KOH solution.

The 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 atomic force microscope. We have found that the Si tip removal volume in moles was in good 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 silica (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.