With the increasing importance of wireless microelectronic devices the need for on-board power supplies is evidently also increasing. Possible candidates for microenergy storage devices are planar all-solid-state Li-ion microbatteries, which are currently under development by several start-up companies. However, to increase the energy density of these microbatteries further and to ensure a high power delivery, three-dimensional (3D) designs are essential. Therefore, several concepts have been proposed for the design of 3D microbatteries and these are reviewed. In addition, an overview is given of the various electrode and electrolyte materials that are suitable for 3D all-solid-state microbatteries. Furthermore, methods are presented to produce films of these materials on a nano- and microscale.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/aenm.201000002

All-Solid-State Lithium-Ion Microbatteries: A Review of Various Three-Dimensional Concepts

High aspect ratio (HAR) silicon etch is reviewed, including commonly used terms, history, main applications, different technological methods, critical challenges, and main theories of the technologies. Chronologically, HAR silicon etch has been conducted using wet etch in solution, reactive ion etch (RIE) in low density plasma, single-step etch at cryogenic conditions in inductively coupled plasma (ICP) combined with RIE, time-multiplexed deep silicon etch in ICP-RIE configuration reactor, and single-step etch in high density plasma at room or near room temperature. Key specifications are HAR, high etch rate, good trench sidewall profile with smooth surface, low aspect ratio dependent etch, and low etch loading effects. Till now, time-multiplexed etch process is a popular industrial practice but the intrinsic scalloped profile of a time-multiplexed etch process, resulting from alternating between passivation and etch, poses a challenge. Previously, HAR silicon etch was an application associated primarily with microelectromechanical systems. In recent years, through-silicon-via (TSV) etch applications for three-dimensional integrated circuit stacking technology has spurred research and development of this enabling technology. This potential large scale application requires HAR etch with high and stable throughput, controllable profile and surface properties, and low costs.

High aspect ratio silicon etch: A review

An intensive study has been performed to understand and tune deep reactive ion etch (DRIE) processes for optimum results with respect to the silicon etch rate, etch profile and mask etch selectivity (in order of priority) using state-of-the-art dual power source DRIE equipment. The
research compares pulsed-mode DRIE processes (e.g. Bosch technique) and mixed-mode DRIE processes (e.g. cryostat technique). In both techniques, an inhibitor is added to
fluorine-based plasma to achieve directional etching, which is formed out of an oxide-forming (O2) or a fluorocarbon (FC) gas (C4F8 or CHF3). The inhibitor can be introduced together with the etch gas, which is named a mixed-mode DRIE process, or the inhibitor can be added in a
time-multiplexed manner, which will be termed a pulsed-mode DRIE process. Next, the most convenient mode of operation found in this study is highlighted including some remarks to
ensure proper etching (i.e. step synchronization in pulsed-mode operation and heat control of the wafer). First of all, for the fabrication ......
 Enjoy reading . Henri Jansen 18 June 2008

https://iopscience.iop.org/article/10.1088/0960-1317/19/3/033001/pdf

Black silicon method X: a review on high speed and selective plasma etching of silicon with profile control: an in-depth comparison between Bosch and cryostat DRIE processes as a roadmap to next generation equipment

Despite the fact that we live in a 3D world and macroscale engineering is 3D, conventional submillimeter-scale engineering is inherently 2D. New fabrication and patterning strategies are needed to enable truly 3D-engineered structures at small size scales. Here, strategies that have been developed over the past two decades that seek to enable such millimeter to nanoscale 3D fabrication and patterning are reviewed. A focus is the strategy of self-assembly, specifically in a biologically inspired, more deterministic form, known as self-folding. Self-folding methods can leverage the strengths of lithography to enable the construction of precisely patterned 3D structures and “smart” components. This self-assembly approach is compared with other 3D fabrication paradigms, and its advantages and disadvantages are discussed.

Frontispiece images reprinted with permission from References25,55,138,80, copyrights 2009, Nature Publishing Group, 2006 and 2007, IOP Publishing, 2001, Conference of Photopolymer Science and Technology, and with permission from Adam Cohen, Microfabrica Inc.

/pdf/three-dimensional-fabrication-at-small-size-scales-3qmffdp3pi.pdf

Three‐Dimensional Fabrication at Small Size Scales

Ordered, hierarchical (triple-scale), superhydrophobic, oleophobic, superoleophobic, and amphiphilic surfaces on poly(methyl methacrylate) PMMA polymer substrates are fabricated using polystyrene (PS) microparticle colloidal lithography, followed by oxygen plasma etching-nanotexturing (for amphiphilic surfaces) and optional subsequent fluorocarbon plasma deposition (for amphiphobic surfaces). The PS colloidal microparticles were assembled by spin-coating. After etching/nanotexturing, the PMMA plates are amphiphilic and exhibit hierarchical (triple-scale) roughness with microscale ordered columns, and dual-scale (hundred nano/ten nano meter) nanoscale texture on the particles (top of the column) and on the etched PMMA surface. The spacing, diameter, height, and reentrant profile of the microcolumns are controlled with the etching process. Following the design requirements for superamphiphobic surfaces, we demonstrate enhancement of both hydrophobicity and oleophobicity as a result of hierarchical (triple-scale) and re-entrant topography. After fluorocarbon film deposition, we demonstrate superhydrophobic surfaces (contact angle for water 168°, compared to 110° for a flat surface), as well as superoleophobic surfaces (153° for diiodomethane, compared to 80° for a flat surface).

From superamphiphobic to amphiphilic polymeric surfaces with ordered hierarchical roughness fabricated with colloidal lithography and plasma nanotexturing.

A. Urban

Papers

Challenges, developments and applications of silicon deep reactive ion etching