Effects of parameters in femtosecond laser micromachining on ablation of silicon

Abstract

Abstract：A series of ablation experiments on silicon surface by femtosecond laser system of 775 nm and 150 fs duration pulses were carried out. The morphological characteristics and the associated effect in the ablation were tested by atomic force microscope (AFM), scanning electron microscope (SEM), focused ion beam (FIB), and the optic microscope. The single pulse threshold can be obtained directly. For the multiple pulses, the ablation threshold varies with the number of pulses applied to the surface due to the incubation effect. By analyzing the experimental data, the thresholds of laser fluences under various laser pulse numbers were obtained, and the relationships between ablation area and laser energy and laser pulse number were concluded. Meanwhile, the periodic ripple structure on silicon surface was found. Under the condition of certain laser power, the number of laser pulse can influence the formation of ripples. Keywords：femtosecond pulse laser; microstructure machining; silicon; ablation threshold; incubation effect Currently, there is considerable interest in the precise material processing of silicon with femtosecond laser. It is well known that the quality of ablated patterns with femtosecond laser on silicon surfaces is much better than in the cases of picosecond and nanosecond [1][2][3][4][5] . The advantages of femtosecond laser make it promising for future applications in precise material processing [6][7][8][9][10][11] .In this paper, the ablation threshold for multiple pulses is reported due to the laser interaction with Si(100) and Si(111) surfaces. Furthermore, when the laser pulse energy is around the material's threshold, the periodic structure, also termed as ripples, on silicon surface, was investigated.

Synthesis and properties of bisphenol‐Z polycarbonate via melt transesterification

“…At present, a few researchers have reported on the synthesis of bisphenol Z-polycarbonate. [16][17][18] However, most of the researchers are using phosgene method to synthesize BPZ-PC, and there are almost no studies on the performance of BPZ-PC. The phosgene process has many adverse effects in the era of green chemistry and environmental protection.…”

Experimental Study on Femtosecond Laser Processing Performance of Single-Crystal Silicon Carbide

“…However, cracks, fragments and recast layers appeared around the ablation crater [8]. In addition, pulse width and wavelength also have a certain impact on material ablation [9,10]. When the pulse width is narrower and the peak fluence is higher, the enhanced ultrafast absorption of laser energy by the material is stronger, resulting in an increase in ablation depth.…”

“…However, when the pulse width decreases to a certain value, the further reduction of the pulse width will lead to an increase in threshold fluence and the width of the groove will not change with the change of pulse width. When the laser wavelength is shorter and the photon energy is greater, the processing accuracy will be higher, the ablation depth will be greater and the ablation threshold will be lower [10].…”