Wear Resistance of N⁺-Implanted Silicon Investigated by Scanning Probe Microscopy

A scanning probe microscope with a 80 nm radius diamond tip was used to investigate the wear resistance of single-crystal silicon and N⁺-implanted silicon. The N⁺ implantation conditions were 35 to 150 keV and 5 × 10¹⁶ ions/cm². The N⁺ concentration depth profile was analyzed by using secondary ion mass spectrometry, and the chemical structure of N⁺-implanted silicon was also analyzed by using x-ray photoelectron spectroscopy. The following results were obtained. The maximum N⁺ concentration on the ion-implanted silicon shifted further below the surface and the thickness of the high ion concentration region increased with the implantation energy. The high N⁺ concentration region using multiple energies of 35–150 keV during the same ion implantation process was wider than that for the N⁺-implanted silicon using a single energy. The wear resistance of ion-implanted silicon was higher than that of single-crystal silicon. The N⁺-implanted silicon using multiple energies during the same ion implantation process showed higher wear durability than that of the N⁺-implanted silicon using a single energy. The Si_2p spectrum of the high N⁺ concentration region implied a structure similar to a Si₃N₄ film, which resulted in higher wear resistance.