Temporal-Spatial Measurement of Surface Morphological Evolution Time in Nanosecond Laser Irradiation on the Copper Film

Shiyong Shangguan,Jianguo Zhang,Yuhan Liu,Hongyu Zheng,Tengfei Sun,Dongfeng Qi

doi:10.3389/fphy.2022.845576

Abstract

In this research, the pump-probe imaging technology and the time-resolved transmittance measurements are used to investigate the transient time scale of the oxidation area, the dewetted melt pool, and the ablation-induced mass transport, and their dependence on the incident laser. Moreover, the evolution time of various morphologies have been studied through a certain delay time from 10 to 30 ns with different dynamic processes. Meanwhile, the underlying formation mechanism and the phase change pathway have been studied. In this regard, a nanosecond (ns) pulsed laser with 532 nm wavelength was used to fabricate nanostructures on the surface of the thin Copper (Cu) films. The observations confirmed that the oxidation process of Cu plays a significant role in the mechanism of laser fluence-dependent oxidation, melting, and ablation dynamics. The results revealed that the different characteristics of the Cu film are related to the incident laser pulse energy. Furthermore, the experimental evidence was in good agreement with the SEM images and the Raman spectra. It is found that the Cu2O surface-rim with a central hole could be fabricated with the laser fluences above the ablation threshold. Although, for the laser fluences below the ablation threshold, the Cu2O phase can be formed in the central region.

Highlights

The processing dynamics of the ns laser on the Cu film using the pump-probe technology and the time-resolved transmittance measurements are investigated in this study
As it can be seen in this figure, if the laser fluence is higher than the ablation threshold, there will be three areas on the surface of the material: the ablation hole area in the center of the spot, the Cu2O granular area around the hole, and the Cu2O film structure around the spot
We have systematically studied the interaction between the laser beam and the Cu thin films and demonstrated the changes of morphological and thermodynamic properties of the Cu thin films during the interaction between the ns laser and the Cu thin films at specific time scales

Summary

INTRODUCTION

Nanostructures are considerably employed in various applications such as microelectronics, optoelectronics, biology, and sensing [1]. The possibility of creating a broad range of nanostructure by selecting the laser parameters (such as energy density, pulse duration, wavelength, and the number of pulses) gives laser-induced nanostructure a distinct advantage over other methods [7] In this process, the laser irradiates to the surface of the substrate and causes deposition of the thin film on the surface of the substrate. Laser-induced nanostructure on the surface of the thin film includes several thermodynamic processes such as gasification, ablation, melting, and oxidation [8, Temporal-Spatial Measurement. The imaging pump-probe technology and time-resolved transmittance measurements were combined to study the evolution of nanosecond (ns) laser-induced Cu film oxidation, dewetting, and ablation over time, paving the way for a better understanding of the nanosecond laser processing on Cu films.

RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT