Resist evaluation for fabrication of diffractive optical elements (DOEs) with sub-micron resolution in a MEMS production line

Abstract

Diffractive optical elements (DOEs) represent small, lightweight and potentially low-cost alternatives to conventional optical components. We have evaluated photoresists and processes for fabrication of silicon micro-machined DOEs with a sub-micron pattern using an MA150 (Suss) proximity aligner. The resists HiPR 6512 (Fuji film), AZ ECI 3007 (AZ Electronics Materials), IX335 H (JSR Micro) and UVIII (Rohm and Haas) were all able to resolve the desired 0.8 µm pattern, but the wall angle obtained with IX335H was a superior 86°. Double development of the resists proved possible in a KOH-based developer but unfeasible in a TMAH-based developer. The final DOE device was successfully realized based on the optimized photolithography process.

Realizing high photovoltaic efficiency with parallel multijunction solar cells based on spectrum-splitting and -concentrating diffractive optical element

“…The design and fabrication of DOE have been extensively developed in the last 40 years. [24][25][26][27][28][29][30] In this paper, the DOE with the functions of spectrum splitting and concentrating is concerned for photovoltaic application. As is well known, the diffraction grating and the focus lens can be used to split the spectrum and concentrate the light, respectively.…”

Wood’s anomalies and spectral uniformity of focusing diffractive optical elements

“…A DOE used for spectroscopy applications would naturally be continuously patterned to take advantage of all the incident optical power. The fabrication of the test DOEs was described in [6], with an emphasis on the photolithography process developed to achieve DOEs with vertical walls within a MEMS processing line. All the DOEs were fabricated in silicon, and sputtered to achieve an approximately 60 nm thick gold layer.…”

“…In this paper we return to the two-level DOE, and report on measurements carried out on a new set of DOEs fabricated at SINTEF ICT. The fabrication of this new set of DOEs was recently presented in [6]. The DOEs were realized with smooth groove walls, as opposed to the two-level DOEs of [3] where the walls were rough.…”

High-Frequency Excitation for Thermal Imprint of Microstructures Into a Polymer

“…Various fabrication technologies are used to manufacture micro or nanostructures. Microstereolithography, 1,2 electron beam lithography, 3 laser‐micromachining, 4,5 and photolithography 6,7 are the methods widely used for the fabrication of prototype microstructures. But most commercial activities have been focused on the replication methods 8,9 …”