Advanced Lithography Simulation for Various 3-Dimensional Nano/Microstructuring Fabrications in Positive- and Negative-Tone Photoresists

Abstract

Photoresist lithography has been applied to the fabrication of micro/nano devices, such as microfluidic structures, quantum dots, and photonic devices, in MEMS (micro-electro mechanical systems) and NEMS (nano-electro-mechanical systems). In particular, nano devices can be expected to present different physical phenomena due to their three-dimensional (3D) structure. The flexible 3D micro/nano fabrication technique and its process simulation have become among the major topics needed to understand nano-mechanical phenomena. For this purpose, the moving-mask technology and the lithography processes for the positive- and negative-tone photoresists were modeled. The validity of the simulation of the proposed 3D nano/microstructuring was successfully confirmed by comparing the experiment results and the simulated results. Hence, the developed model and the simulation can present and optimize photoresist characteristics and lithography process conditions due to the various 3D nano/microstructures. They could be help in the understanding of nanomaterial and mechanical phenomena.

Sensitivity of Process Parameters on Pattern Formation of Litho–Cure–Litho–Etch Process

“…where [M] is the protective group of the polymer resin, [B] is the base quencher concentration, k amp is the acid catalyzed deprotection rate, k loss is the acid loss reaction rate, k quench is the acid neutralization rate, t is PEB time, and D acid (or D quench ) is the diffusion length of acid (or quencher). [23][24][25] Cross-linked polymer concentrations without and with cured patterns are different in Figs. 2(d) and 2( j).…”

Moving-mask Lithography for 3D Microstructure Molding

“…Such microneedles have been formed by molding, in which control of the sidewall inclination angle of the microstructures is very important. For this purpose, techniques such as inclined deep X-ray lithography [3], double-exposure deep X-ray lithography [4], moving mask X-ray lithography [5][6][7], gray-scale lithography [8], inclined UV lithography [9], moving-mask UV lithography [10][11][12], backside lithography [13,14] and deep UV lithography using diffraction [15][16][17][18] have been investigated. X-ray lithography requires a synchrotron, which is prohibitively expensive for many microsystem laboratories [3][4][5][6][7]9,10].…”