High-energy femtosecond laser induced collateral damages on silicon and glass

High-energy laser pulses are utilized to ablate the unpolished surface of silicon wafer and slide glass and morphology and nanomechanical properties of the sample surface are characterized. The morphology on the ablated front surface is measured by a microscope. The morphology on the front surface of silicon wafer varies with positions, yet there is a distinct boundary between the ablated and unablated areas on the front surface of slide glass. The morphology on the smooth back surface is characterized by AFM. After irradiation, there are no prominent changes in morphology on the back surface of silicon wafer. While, the morphology on the back surface of slide glass is markedly changed by laser pulses, and there is also a clear boundary between the back of the ablated zone and the back of the unablated zone. Nanomechanical properties on the back surface of the two samples are measured by a commercial nanomechanical test system. Regular variations in nanomechanical properties corresponding to that in morphologies on the ablated front surface occur on the back surface of silicon wafer. Yet such regular variations do not appear on the back surface of slide glass. The regular changes in morphology and nanomechanical properties, to some extent, show the distribution of collateral damages, which is induced by the ill effects during high-energy femtosecond laser ablation.