Comparative study of soft thermal printing and lamination of dry thick photoresist films for the uniform fabrication of polymer MOEMS on small-sized samples

Abstract

The aim was the uniform fabrication of high aspect ratio polymer-based MOEMS (microoptical-electrical-mechanical system) on small and/or fragile samples, such as GaAs. The printing conditions were optimized, and the resulting thickness uniformity profiles were compared to those obtained via lamination and SU-8 standard spin-coating. Under the best conditions tested, STP and lamination produced similar results, with a maximum deviation to the central thickness of 3% along the sample surface, compared to greater than 40% for SU-8 spin-coating. Both methods were successfully applied to the collective fabrication of DF1050-based MOEMS designed for the dynamic focusing of VCSELs (vertical-cavity surface-emitting lasers). Similar, efficient electro-thermo-mechanical behaviour was obtained in both cases.

Liquid-Crystal Alignment by a Nanoimprinted Grating for Wafer-Scale Fabrication of Tunable Devices

“…DF-1000 series are dry thick resist films that present similar optical and mechanical properties than SU-8, while being easier to implement, of lower cost, and having a better thickness reproducibility than spin-coated SU-8 whatever the substrate PTL-34473-2018 shape and size (4.8 ± 0.2µm for DF-1005 films) [17]. The DF-1005 film is printed on the mirror's surface by soft thermal transfer (Fig.2(c)) [18]. It is worth noting that the NIL setup we used is equipped with a double-sided flexible chamber that ensures an isostatic pressure on the wafer (Nanonex NX-2500) [12].…”

Implementation of Integrated VCSEL-Based Optical Feedback Interferometry Microfluidic Sensor System with Polymer Microoptics

“…This equipment is suitable for handling brittle and small-sized samples (Figure 2a-d). This technique was previously developed by the authors to optimize the uniformity of thick resist layers on GaAs samples (a quarter of a wafer with a surface of a few cm 2 ) [27]. As the nominal thickness of a single DF-1050 film is only 48 µm, three films had to be successively printed on the chip to obtain a pedestal height greater than 100 µm.…”

Uniform Fabrication of Moems Arrays Using Dry Thick Resist Films

“…The process was thus adapted to make the use of dry films on such samples possible using a new transfer method called "soft thermal printing" and based on the use of a nanoimprint setup. Thanks to this new method, it was possible to reduce the thickness variation along the whole sample to less than 3% compared to the greater than 40% variation obtained by standard SU-8 spin-coating on the same surface (quarter of wafer of 2" in diameter) [5]. Two metallization steps were then achieved before DF-1050 development (Figure 3d).…”