Fabrication techniques for multiscale 3D-MEMS with vertical metal micro- and nanowire integration

Abstract

This paper presents different low-temperature and high-throughput LIGA-like processes for the batch fabrication of metal micro systems that use long nano- or microwires perpendicularly rising from a substrate. First, circuit paths and seed layers are fabricated applying standard UV lithography and PVD. Second, three lithography techniques are used, namely ion track lithography, enhanced UV lithography and aligned x-ray lithography, to structure 20–400 µm thick polymer films. Ion track lithography is only used to fabricate extremely high aspect ratio cylindrical pores with 0.1–1 µm diameter and 20–100 µm length. The aligned UV and x-ray lithographies are employed to structure templates for various micro system components. Third, these polymer templates are filled using low-temperature electroplating processes transferring the polymer openings into metal structures. Finally, the polymer is dry etched to release all metal structures. These structures are applicable in future accelerometers and gas flow sensors. Using five configurations to define five different functional structures, we demonstrate fabrication processes applying the three different types of lithography. The main aspects concern the combination of both standard lithography techniques and especially developed lithography techniques. Furthermore, these aspects comprise the use of structures created by lithography for high aspect ratio polymer templates and multilayer electroplating with varying aspect ratios. The growth in place of nanowire arrays and micropillars along with surrounding structures is the key feature for low-temperature large-scale micro-nano integration technology without harmful transfer technologies.

Quick and easy microfabrication of T-shaped cantilevers to generate arrays of microtissues

“…The current approaches thus require two photomasks and four layers of two to five different photoresists, meaning long and numerous spin-coating, baking and exposure steps, the whole process lasting over more than 10h (Liu et al 2014; Ramade et al 2014). Recently, Greiner et al reported the possibility of microfabricating 170 µm-tall structures with a single layer of the positive photoresist AZ 40XT (Greiner et al 2013). We thus built on these results to elaborate a novel approach necessitating only two layers of photoresist.…”

B3.4 - Hot Stamped Conductors on Nano-Micro Wires Made by Electroplating for Medical Sensors and Micro-Implants

“…The galvanic deposition is done potentiostatically with a 2 or 3 electrodes arrangement on a hotplate to control temperature. Detailed information about the process is given in [5] and [7].…”

“…Nanowires are investigated in several applications such as acceleration sensor [5], gas flow sensor [5] or humidity micro switch [6]. This new approach provides permanent electrical conductivity by penetrating the conductive layer of hot stamping foils with nanowires.…”

3D Carbon Microelectrodes with Bio-Functionalized Graphene for Electrochemical Biosensing

“…Therefore, a rational design of the electrodes and an increase in electrode surface area for the same overall electrode footprint area are potential strategies for improving the performance of electrochemical biosensors. A frequently used approach to achieve this involves the integration of nanomaterials, such as CNTs or nanoparticles, into the sensor electrode [ 14 ] Several microfabrication processes have been reported for the fabrication of three-dimensional (3D) microelectrodes [ 15 , 16 , 17 , 18 , 19 ]. In the last few years, 3D electrodes have shown very promising results for diverse electrochemical applications [ 20 , 21 ].…”