Dry fabrication of microdevices by the combination of focused ion beam and cryogenic deep reactive ion etching (original) (raw)
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Sensors and Actuators A: Physical, 2005
Micromachining arbitrary 3D silicon structures for micro-electromechanical systems can be accomplished using gray-scale lithography along with dry anisotropic etching. In this study, we have investigated the use of deep reactive ion etching (DRIE) and the tailoring of etch selectivity for precise fabrication. Silicon loading, the introduction of an O 2 step, wafer electrode power, and wafer temperature are evaluated and determined to be effective for coarsely controlling etch selectivity in DRIE. The non-uniformity and surface roughness characteristics are evaluated and found to be scaled by the etch selectivity when the 3D profile is transferred into the silicon. A micro-compressor is demonstrated using gray-scale lithography and DRIE showing that etch selectivity can be successfully tailored for a specific application.
Journal of Micromechanics and Microengineering, 2007
A fast, dry microfabrication process combining atomic layer deposition, electron beam lithography and cryogenic deep reactive ion etching is presented. The process exploits the extremely high selectivity of atomic layer deposited amorphous Al 2 O 3 (alumina) to silicon in cryogenic etching by using an ultra-thin (t 5 nm) Al 2 O 3 film as a mask. The process rules and limitations are carefully analyzed and a thorough understanding of the limiting factors is reached, and the effect of the limitations on the critical output current of a dc-biased clamped-clamped beam is studied. To test the process, multiresonant tuning fork resonators are fabricated and found to exhibit Q ≈ 8000 at f r ≈ 11.4 MHz. Both values are the highest reported for resonators fabricated with the dry process and comparable with values achieved with existing silicon micromachining processes.
Nanostructure fabrication by reactive-ion etching of laser-focused chromium on silicon
Applied Physics B: Lasers and Optics, 1998
We have fabricated chromium nanostructures on silicon by laser-focused atomic deposition, and have further processed these structures by reactive-ion etching in an SF plasma. We show that the result can be an array of parallel wires as narrow as 68 nm, or an array of parallel Si trenches as narrow as 85 nm. The laser-focused deposition process is inherently parallel, so a large area is patterned simultaneously with an accurate periodicity of 212.78 nm.
A survey on the reactive ion etching of silicon in microtechnology
Journal of Micromechanics and Microengineering, 1996
This article is a brief review of dry etching as applied to pattern transfer, primarily in silicon technology. It focuses on concepts and topics for etching materials of interest in micromechanics. The basis of plasma-assisted etching, the main dry etching technique, is explained and plasma system configurations are described such as reactive ion etching (RIE). An important feature of RIE is its ability to achieve etch directionality. The mechanism behind this directionality and various plasma chemistries to fulfil this task will be explained. Multi-step plasma chemistries are found to be useful to etch, release and passivate micromechanical structures in one run successfully. Plasma etching is extremely sensitive to many variables, making etch results inconsistent and irreproducible. Therefore, important plasma parameters, mask materials and their influences will be treated. Moreover, RIE has its own specific problems, and solutions will be formulated. The result of an RIE process depends in a non-linear way on a great number of parameters. Therefore, a careful data acquisition is necessary. Also, plasma monitoring is needed for the determination of the etch end point for a given process. This review is ended with some promising current trends in plasma etching.
Focused Ion Beam Lithography to Etch Nano-architectures into Microelectrodes
Journal of Visualized Experiments
With advances in electronics and fabrication technology, intracortical microelectrodes have undergone substantial improvements enabling the production of sophisticated microelectrodes with greater resolution and expanded capabilities. The progress in fabrication technology has supported the development of biomimetic electrodes, which aim to seamlessly integrate into the brain parenchyma, reduce the neuroinflammatory response observed after electrode insertion and improve the quality and longevity of electrophysiological recordings. Here we describe a protocol to employ a biomimetic approach recently classified as nano-architecture. The use of focused ion beam lithography (FIB) was utilized in this protocol to etch specific nano-architecture features into the surface of non-functional and functional single shank intracortical microelectrodes. Etching nano-architectures into the electrode surface indicated possible improvements of biocompatibility and functionality of the implanted device. One of the benefits of using FIB is the ability to etch on manufactured devices, as opposed to during the fabrication of the device, facilitating boundless possibilities to modify numerous medical devices post-manufacturing. The protocol presented herein can be optimized for various material types, nano-architecture features, and types of devices. Augmenting the surface of implanted medical devices can improve the device performance and integration into the tissue.
Applied Physics Letters, 2004
This letter describes a simple method for three-dimensional microfabrication of complex, high-aspect-ratio structures with arbitrary surface height profiles in bulk silicon. The method relies on the exploitation of reactive ion etching lag to simultaneously define all features using a single lithographic masking step. Modulation of the mask pattern openings used to define the features results in etch depth variation across the pattern, which is then translated into surface height variation through removal of the superstructure above the etched floors. Utilization of a nonisotropic superstructure removal method based on sacrificial oxidation enables definition of high-aspect-ratio structures with vertical sidewalls and fine features. The utility of the approach is demonstrated in the fabrication of a sloping electrode structure for application in a hybrid micromirror device.
Dry Etching Based Silicon Micromachining for MEMS
The aim of this work is to demonstrates the "dry" etching based micro-fabrication technologies in the manufacturing of Single Crystal Silicon (SCS) for Micro-Electro/(Optical)-Mechanical-Systems (ME(O)MS). The ME(O)MS technology is very fast growing industry branch based often on the same silicon technology as integrated circuits. The process of plasma-dry etching is quite simple straightforward and can be considered as the key technology in the micromachining of silicon. The most important motivation for this work is the critical issues in dry etching methods as technologies that enable the advancement of the micromachining industry. The basic aspects of pattern transfer of the prepared resist-patterns by plasma etching into the substrate, under considering the plasma chemistry, gas flow or gas chopping, and substrate temperature will be presented. Special attention will be given to discuss the physical and chemical phenomena which are involved in the generation of features with high aspect ratios.