Fabrication of CMOS-compatible nanopillars for smart bio-mimetic CMOS image sensors

Abstract

In this paper, nanopillars with heights of 1µm to 5µm and widths of 250nm to 500nm have been fabricated with a near room temperature etching process. The nanopillars were achieved with a continuous deep reactive ion etching technique and utilizing PMMA (polymethylmethacrylate) and Chromium as masking layers. As opposed to the conventional Bosch process, the usage of the unswitched deep reactive ion etching technique resulted in nanopillars with smooth sidewalls with a measured surface roughness of less than 40nm. Moreover, undercut was nonexistent in the nanopillars. The proposed fabrication method achieves etch rates four times faster when compared to the stateof-the-art, leading to higher throughput and more vertical side walls. The fabrication of the nanopillars was carried out keeping the CMOS process in mind to ultimately obtain a CMOScompatible process. This work serves as an initial step in the ultimate objective of integrating photo-sensors based on these nanopillars seamlessly along with the controlling transistors to build a complete bio-inspired smart CMOS image sensor on the same wafer.

Integrated Bio/Nano/CMOS interfaces for electrochemical molecular sensing

“…Carbon nanotubes have been also precisely transferred onto micro‐fabricated multipanel systems by using approaches based on electrochemical polymerization as well as by transfer‐printing . Silicon nanowires as well as nanopillars have been fabricated by chemical etching in a CMOS‐compatible way. Electrodeposition has been proposed as well for the deposition of both nano‐gold and nano‐platinum .…”

Silicon nanostructures with very large negatively tapered profile by inductively coupled plasma-RIE

“…5 Unlike anisotropic etching of silicon by potassium hydroxide, which gives only a fixed taper angle of 35.5 , 6 dry etching is crystalline orientation independent with tunable taper angle and is thus a more versatile process and may find applications for highly efficient light capturing for imaging and solar energy harvesting. 7,8 However, only few studies in the literature were reported regarding the means of obtaining structures with negatively tapered profile, which can be used for many applications. One application is to use negatively tapered silicon structures to make hydrophobic and omniphobic surfaces that repel both water and oil.…”