Femtosecond Laser Precision Engineering: From Micron, Submicron, to Nanoscale

Zhenyuan Lin,Minghui Hong

doi:10.34133/2021/9783514

Abstract

As a noncontact strategy with flexible tools and high efficiency, laser precision engineering is a significant advanced processing way for high-quality micro-/nanostructure fabrication, especially to achieve novel functional photoelectric structures and devices. For the microscale creation, several femtosecond laser fabrication methods, including multiphoton absorption, laser-induced plasma-assisted ablation, and incubation effect have been developed. Meanwhile, the femtosecond laser can be combined with microlens arrays and interference lithography techniques to achieve the structures in submicron scales. Down to nanoscale feature sizes, advanced processing strategies, such as near-field scanning optical microscope, atomic force microscope, and microsphere, are applied in femtosecond laser processing and the minimum nanostructure creation has been pushed down to ~25 nm due to near-field effect. The most fascinating femtosecond laser precision engineering is the possibility of large-area, high-throughput, and far-field nanofabrication. In combination with special strategies, including dual femtosecond laser beam irradiation, ~15 nm nanostructuring can be achieved directly on silicon surfaces in far field and in ambient air. The challenges and perspectives in the femtosecond laser precision engineering are also discussed.

Highlights

Surface engineering in micro-/nanoscales plays a major role in a material’s performance improvement [1, 2]
Multiscale surface engineering is a key issue in developing novel material structures and the analysis of behavior that exist at surfaces and interfaces
Subdiffraction limited creations at a scale of dozens of nanometers using multiphoton absorption, thresholding, stimulation emission depletion (STED) effect, and incubation effect have been realized in various materials [29,30,31]

Summary

Introduction

Surface engineering in micro-/nanoscales plays a major role in a material’s performance improvement [1, 2]. Laser direct writing has shown its great ability from micron, submicron, to nanoscale applications, including semiconductor devices [16, 17], micro-/nanofluidics [18,19,20], biotechnology [21], and sensors [22], on various materials [23,24,25]. In combining with advanced manufacturing strategies, the feature size of femtosecond laser precision engineering has been reduced to ~15 nm in the lab [32,33,34], far smaller than the optical diffraction limit, which would be an important and feasible way for the generation nanofabrication. To pursue the nanofabrication in far field, the strategies of multiphoton absorption (MPA) and incubation effect are developed, the minimum feature size at ~15 nm can be obtained, which may be further reduced by the fine control of the femtosecond laser precision processing. The challenges and perspectives for the femtosecond laser precision engineering are discussed

Basic Theory and Development of Ultrafast Laser Processing

15 KV x100

Challenges, Outlooks, and Conclusions