Plasma chemical etching of high-aspect-ratio silicon micro- and nanostructures

Abstract

High-aspect-ratio (HAR) silicon etching of micro-and nanostructures in a time-multiplexed deep etching process (Bosch process) is reviewed, including applications, different technological methods, critical challenges, and main principles of the technologies. HAR silicon etching is an application associated primarily with micro-and nanostructures. This potentially large-scale application requires HAR etching with a high throughput and controllable profile and surface properties. The most significant effects like RIE lag, bowing, stop effect, and profile shape dependence are discussed.

Microsphere Handling at the Microscale: New Tools and New Effects

“…Figs. 4.13&4.14), justifying the switch from standard perforated membranes to profiled membranes as postulated in Chapter 3.3.…”

“…Similar to the results obtained in section 4.3.2, it can inferred from Figs. 4.16a1&b1 that we are able to assemble the agitated (f = 250 Hz; A = 82 µm) 10 µm PS particles inside the micromachined groove structures. However, the grooves and surrounding silicon surface are abundantly covered with these particles.…”

“…The quality of etched structures fabricated using dry plasma etching systems depends on a vast number of parameters, e.g., etch times, polymer thickness, flow rate and composition of the mixtures, pressure and RF power. [4] Hence, tailoring a recipe to fabricate structures is a rather sophisticated process. When doing so, one should keep in mind that it is imperative that the right balance exists between the etching and passivation steps.…”

“…When doing so, one should keep in mind that it is imperative that the right balance exists between the etching and passivation steps. [4] Changing a single parameter may require adaptation of others as well to obtain the desired shape of a structure, i.e. a universal recipe to etch structures using plasma etching techniques is absent.…”

“…From Figs. 4.13a&b it can readily be observed that the silica particles assemble on the though-pores of the membrane, but with a large number of excess particles 2 MV m −1 and removal of the excess particles using a brush for three instances. In all of these conditions, the vacuum force is maintained, while removing the excess particles using the brush.…”