Thick photoresist development for the fabrication of high aspect ratio magnetic coils

Abstract

This paper reports the fabrication of coils for micro-magnetic devices on silicon using thick photoresists commonly used in the manufacture of microelectromechanical systems. A comparison of three photoresists, EPON SU-8, AZ 4562 and AZ 9260, is presented for the fabrication of high aspect ratio conductors. With a thickness of 81 μm, aspect ratios of 6:1 are obtained using the AZ 9260 photoresist. RF inductors and micro-transformers for power conversion applications are fabricated using this technology. The quality factor of the RF inductors shows maximum values of 23 at 0.4 GHz. Very good measurement is also obtained with the micro-transformers: the resistance of the electroplated copper windings is 0.3 Ω up to 2 MHz.

Fabrication of 3D air-core MEMS inductors for very-high-frequency power conversions

“…Because of the isotropic etching profile, the pitch between nearby turns is limited. To reduce the winding pitch, alternative methods are mould-based electroplating 19,20,43 and anisotropic plasma etching of Cu [44][45][46] .…”

“…One method to fabricate on-substrate high-aspect-ratio 3D inductors is to use UV-LIGA lithography with SU-8 negative resist. The resist structures serve as electroplating molds and sacrificial layer [19][20][21] or supporting pillars 22,23 for the electrodeposition of conducting metals. The second category is embedded inductors, in which the inductors are embedded inside the Si substrate and utilize the unused substrate volume.…”

Micro-fabrication of high-thickness spiral inductors for the remote powering of implantable biosensors

“…Ref. [10] describes the fabrication of thick inductors by using different types of photoresist. EPON SU8, AZ4562, and AZ9260 are considered 0167-9317/$ -see front matter Ó 2013 Elsevier B.V. All rights reserved.…”

Simulation and Fabrication of the Cone Sheet for LCD Backlight Application

“…A PET film of size 100 mm×100 mm was placed on the chuck of a spin coater and the photoresist SU-8 that is transparent in the visible range was spin-coated to make a photoresist film of thickness 50 μm. A two-step soft baking was performed during 10 minutes at 65℃ and 30 minutes at 95℃ on a hot plate in order to remove the volatile agents completely [10]. The exposure was performed during 10 minutes by ultraviolet in a setup for the diffuse lithography that is comprised of an opal diffuser, a photomask, and a PET film substrate as shown in Fig.…”