Fabrication of micro-structures using non-planar lithography (NPL)

Abstract

Progress in the development of Micro Electro Mechanical Systems (MEMS) has been limited by deficiencies in two broad areas: (1) a lack of knowledge of the physical behavior of interacting micro systems (phenomena such as micro-mbology, -fluid mechanics, -electrostatics, -elecmcal discharge, etc.), and (2) limitations in available fabrication methodologies (photolithography, sputtering, etching, etc.). This paper addresses the second problem by presenting specific Non-Planar Lithographic OJPL) techniques for use in fabricating both monolithic micromachines and microcomponents for use in larger systems. The emphasis here is on the use of numerically-controlled E-beam-based lithography, with the resist exposed over non-planar surfaces. Previously, non-planar, optical-mask-based approaches have been used to fabricate devices such as wobble motor rotors, but with less success than the NPL techniques due to depth-of-field problems.The specific focus is on etching cylindrically-shaped metal structures which are either (1) homogeneous or (2) layered by successive deposition, masking, and etching. Structures on the order of 80 to 500 microns in diameter have been constructed of either solid metals, or sputtered thin metallic layers on quartz shafts. A number of either deep or shallow patterns have been fabricated on and through the structures, with promising results. Examples include; helices, longitudinal lines, holes, notches, flexures, barbs, alphanumeric characters, and electrostatic field emitting patterns for use in wobble motors. Efforts are now proceeding toward generating complete systems, including transducers and actuators for industrial and medical applications.

Digital image correlation for grain scale strain measurement in interstitial free high strength steel

“…In this technique, physical grids are not laid on the specimen surface as practised by lithography. [31][32][33][34] But in this experiment, an imaginary grid is placed on the reference image. It has been done in a manner so that the grid covers the grains over the area of interest on the specimen surface (Fig.…”

Three-Dimensional Metallic Microstructures Fabricated by Soft Lithography and Microelectrodeposition

“…The use of photolithography (which is inherently planar) and e-beam lithography (which is a serial technique) limits traditional through-mask electroplating to the fabrication of 2D microstructures with high aspect ratios. Patterning cylindrical substrates has been accomplished using an e-beam system modified with a stage that allows the rotation and translation of a fiber during the writing step and using a lathe to control the orientation of a cylinder relative to an X-ray mask and source . The equipment required for either of these techniques makes them inaccessible to most researchers.…”

Simultaneous biochemical and topographical patterning on curved surfaces using biocompatible sacrificial molds

“…The production of structured and functionalized, enclosed structures, such as tubes,4–6 would be particularly useful. The fabrication of such enclosed 3D structures and, in particular, the fabrication of microstructures inside tubes is possible using a layer‐by‐layer approach to build the mold 7. This versatile technique, based on conventional lithography, is able to reproduce almost any solid volume.…”