3D femtosecond laser nanoprinting, "three high" characteristics, to achieve high-precision 3D processing

3D femtosecond laser nanoprinting, "three high" characteristics, laserpecker 12 to achieve high-precision 3D processing

In recent years, with the extensive development of various micro and nano devices in the fields of optics, photochemistry, optoelectronics, nanophotonics and bionics, the corresponding 3D micro and nano processing technology has gradually become an important part of the processing technology.

In order to maximize the functionalization of materials and improve the working efficiency of devices, 3D micro and nano machining has high requirements for the accuracy, dimension, scale and speed of processing enterprises, and these problems require the development of traditional micro and nano machining methods and means to face great risks and challenges. laserpecker metal engraving In order to meet the high precision and high efficiency of 3D micro and nano processing products, 3D femtosecond laser nanoprinting information technology research came into being.

3D femtosecond laser nanofrint is a maskless processing technology with 3D, deep nanoscale resolution and arbitrary structural design. The technical characteristics of 3D femtosecond laser nanoprinting can be summarized as "three high", that is, high precision, high design and high function.

These three technical characteristics are derived from the ultra-fast laser characteristics such as the high-energy pulse of the femtosecond laser. Taking medium laser power as an example, the energy density of femtosecond laser radiation is as high as 1013 Wu002Fμm2. Such a high pulse energy makes the processing mechanism of 3D femtosecond laser printing different from previous processing methods, which is reflected in two aspects: thermal effect suppression and nonlinear absorption. The femtosecond laser has an ultra-short pulse of ten to several hundred femtoseconds, and its energy absorption time is much shorter than the time required for dynamic processes such as thermal relaxation, so the thermal effect in the laser scanning area can be effectively suppressed. In other words, the femtosecond laser can be seen as a cold therapy tool. The high-energy pulse of femtosecond laser also makes the interaction between light and matter completely different from continuous laser, which is reflected in the nonlinear absorption of matter to femtosecond laser, that is, two-photon or multi-photon absorption.

Due to this nonlinear absorption property, femtosecond laser processing not only achieves resolutions well beyond the optical diffraction limit (below 10nm), but also has a wide range of material handling capabilities, from soft polymer materials to hard materials such as metals, semiconductors, and dielectric materials. Corresponding photophysical and photochemical processes also include ablation, photopolymerization, photoreduction and photoisomerization, which also stimulate a wealth of physical and chemical phenomena and mechanisms. It can be seen that 3D femtosecond laser nanoprinting uses femtosecond laser as a processing tool, which is different from other processing methods due to its unique nonlinear characteristics, and is a powerful 3D processing technology with material versatility.

3D femtosecond laser nanoprinting

Basic principle

Two-photon polymerization means that when the femtosecond laser interacts with matter, the electrons in the photopolymer absorb two infrared photons (their energy sum is equivalent to one ultraviolet photon) at the same time in a quantum process, so as to achieve a transition from the ground state to the excited state. In this process, the two-photon absorption rate is proportional to the square of the light intensity. So two-photon polymerization can only occur if the light intensity is high enough. Two-photon polymerization is the most typical representative of 3D femtosecond laser nanoprinting technology, which has a wide range of applications in circuit processing and integration.

The two-photon polymerization development has the key characteristics typical of enterprise technology for 3D femtosecond laser nanocurrying, namely high resolution and powerful 3D patterning capabilities. Its resolution, that is, the minimum system characteristics and size of the industrial structure being processed, is about 10 nm. Generally, in the minimum working characteristics of λ /10~λ /50 (λ is the wavelength) of different size information processing time range, the femtosecond laser is focused through a high numerical aperture lens to converge into a small spot, so that the spot has a high photon energy density. Specifically, the two-photon polymerization method has three nonlinear effects: optical nonlinearity, chemical nonlinearity and material use nonlinearity. The integrated management effect of these three aspects was not effective and finally we decided on the deep subwavelength resolution of the processing production technology in this way.

Comparison of 3D femtosecond laser nanoprinting based on two-photon polymerization and traditional 3D laser printing. Compared with the previous laser rapid prototyping, 3D femtosecond laser nanoprinting technology has a unique two-photon polymerization processing mechanism, high precision, high processing quality, simple function, easy integration and so on.

The unique advantage of femtosecond laser processing is the use of two-photon absorption technology to ensure that the above process can only be realized at the focal point, so as to achieve three-dimensional high-precision processing.

Materials prepared by two-photon polymerization have been extended from polymer photoresist to proteins, metal nanostructures, metal oxides, carbon materials and composite structures. In theory, as long as a set of appropriate photochemical or photophysical mechanisms are established, many materials can be used as processing objects for two-photon polymerization.