Wet Selective SiGe Etch to Enable Ge Nanowire Formation

For the Ge nanowire formation in a gate-all-around (GAA) integration scheme, a selective etch of Si0.5Ge0.5 or Si0.3Ge0.7 selective to Ge is considered. Two wet process approaches were evaluated: a boiling TMAH as a commodity chemistry is compared with a formulated chemistry using a multi-stack SiGe/Ge layer as a test vehicle. The boiling TMAH exhibits an anisotropic etch of the SiGe whereas the formulated semi-aqueous chemistry removes the sacrificial SiGe by an isotropic etch which makes the process suitable for a Ge nanowire release process.

Modeling, Fabrication, and Testing of a Nanoinjection Lance Array for Simultaneous Multi-Cell Injections

A nanoinjection lance array has been developed to inject foreign genetic material into thousands of cells at once using electrophoresis to attract and repel particles to and from the lances. A unique combination of isotropic and anisotropic etch processes are used to fabricate the four million 1 μm by 8 μm solid lances on a 2 cm by 2 cm chip. Initial studies show high cell viability when the lance array is used to pierce through a culture of HeLa cancer cells, often used for genetic research. A mathematical computer model simulating motion of attracted or repelled particles informs the design of the nanoinjection lance array system. The nanoinjection lance array provides an efficient, convenient, and quick way to simultaneously inject thousands of cells for a wide range of genetic research applications.

Investigating GaSb(001) Dry Etching by ICP-RIE on a non-Silicon Containing Sample Holder with no Organic Gases

ABSTRACTWe report the dry etch of GaSb(001) by inductively coupled plasma reactive ion etcher. Silicon Oxide, deposited by PECVD, was used as a mask. The oxide layer proved to be almost unaffected compared to the GaSb, when using chlorine compound gases as etchants (Cl2, BCl3, and SiCl4) as well as argon. This provides high selectivity for GaSb to the mask layer. The sample holder has no silicon that may contribute to the etching process. Etching using Cl2 + Ar showed increase in the etching rate as the chlorine ratio increases; however, the process led to grassy surface and chemical like reaction. The use of SiCl4+Cl2+Ar mixture with low chlorine ratio resulted in anisotropic etch with smooth sides. It has been found for this case that the increase of the chlorine ratio led to an increased etching rate as well. The repeat of previously reported result by Swaminathan et al. [Thin Solid Films 516 (2008) 8712.] yet with a sample holder not having silicon, proved the effect of Si-contribution in producing vertical profile etch with smooth surfaces.

Various methods used to etch titanium dioxide columnar thin films

A dry etch recipe was developed for porous nanostructured TiO2 thin films fabricated using glancing angle deposition (GLAD). Unlike wet chemical etches, the technique reported here preserves the vertical post nanostructure, eliminating clumping. A highly controllable and easily tailored reactive ion etching process with CF4 alone, or combined with O2, was investigated. The anisotropic etch modifies the morphology and density of standard GLAD films, which is of interest for sensing applications.

Systematic Characterization of DRIE-Based Fabrication Process of Silicon Microneedles

This paper reports on the systematic characterization of a deep reactive ion etching based process for the fabrication of silicon microneedles. The possibility of using such microneedles as protruding microelectrodes enabling to electroporate adherently growing cells and to record intracellular potentials motivated the systematic analysis of the influence of etching parameters on the needle shape. The microneedles are fabricated using dry etching of silicon performed in three steps. A first isotropic step defines the tip of the needle. Next, an anisotropic etch increases the height of the needle. Finally, an isotropic etch step thins the microneedles and sharpens their tip. In total, 13 process parameters characterizing this etching sequence are varied systematically. Microneedles with diameters in the sub-micron range and heights below 10 µm are obtained. The resulting geometry of the fabricated microneedles is extracted from scanning electron micrographs of focused ion beam cross sections. The process analysis is based on design-of-experiment methods to find the dominant etch parameters. The dependence of the needle profiles on process settings are presented and interpolation procedures of the geometry with processing conditions are proposed and discussed.

SILICON FIBRE TECHNOLOGY DEVELOPMENT FOR WEARABLE AND AMBIENT ELECTRONICS APPLICATIONS

The concept of silicon fibre technology follows the aspiration of making whole computers recede into textile format, which can be used in a wearable or ambient environment. The integration of IC technology into fibre format is an important development for a wide range of emerging scientific applications from wearable vital sign health monitoring systems [1] to Ambient Intelligence Microsystems. This concept is achieved by building a device in silicon on insulator (SOI) [2] material and under-cutting the sacrificial SiO 2 layer by a combination of isotropic and anisotropic etch processes, to leave a freestanding functional fibre. A demonstration of functionality based on this technology was produced in the form of a PN diode on a fibre [3]. After demonstrating the feasibility of the concept, subsequent active device circuits were designed and fabricated as a more complex demonstration of functionality. One of the primary considerations involved with this technology is the interconnection of these flexible silicon structures to each other and to the outside environment. A novel interconnection protocol has been developed and a prototype demonstration of a flexible LED circuit has been fabricated.