Materials and technologies for fabrication of three-dimensional microstructures with sub-100 nm feature sizes by two-photon polymerization

Abstract

The fabrication of sub-100 nm feature sizes in large-scale three-dimensional (3D) geometries by two-photon polymerization requires a precise control of the polymeric reactions as well as of the intensity distribution of the ultrashort laser pulses. The authors, therefore, investigate the complex interplay of photoresist, processing parameters, and focusing optics. New types of inorganic– organic hybrid polymers are synthesized and characterized with respect to achievable structure sizes and their degree of crosslinking. For maintaining diffraction-limited focal conditions within the 3D processing region, a special hybrid optics is developed, where spatial and chromatic aberrations are compensated by a diffractive optical element. Feature sizes below 100 nm are demonstrated.

3D Micro-Optics Via Ultrafast Laser Writing: Miniaturization, Integration, and Multifunctionalities

“…For comparison with recent study performed by Jiang et al [31], the range of employed velocities by almost two orders of magnitude was increased to expand discussion on photochemical conversion. Also, the achieved maximum value of degree of conversion is in close agreement with the results published in Refs [30,106]. 12.1.8 in all cases.…”

“…12.1.8 in all cases. [30] no saturation in conversion close to the damage threshold of the prepolymer was observed. [106] and, now, is demonstrated experimentally.…”

“…Interest begins to grow up in synthesis of new materials leading to the fabrication throughput and resolution optimization. The degree of conversion in cross-linking was investigated using coherent anti-Stokes Raman spectroscopy (CARS) [105], Fourier transform infrared (FTIR) spectroscopy [106], and Raman microspectroscopy [30,31]. Photopolymers used for the TPP were characterized for their Young's modulus by nanoindentation technique [101].…”

“…For instance, the materials designed for 3D direct laser writing (DLW) are not fully (or barely at all) characterized [30,31] and their optical performance and reliability [32,33] have to be established. For instance, the materials designed for 3D direct laser writing (DLW) are not fully (or barely at all) characterized [30,31] and their optical performance and reliability [32,33] have to be established.…”

Microfabrication of 3D metallic interconnects via direct laser writing and chemical metallization

“…Up to now much effort has been made in hybrid (organic-inorganic) material synthesis specialy designed for DLW 3D micro-/nanostructuring [48]. ORMOCER (ORganically MOdified CERamics) and ORMOSIL (ORganically MOdiefied SILica) class materials offer optimal laser structuring, mechanical, chemical, and biological properties [49]. Sequentially, composite sol-gel synthesized hybrids with metal binding afinities were inroduced [6].…”