Integration of Thin‐Film‐Fracture‐Based Nanowires into Microchip Fabrication

Abstract

One-step device fabrication through the integration of nanowires (NWs) into silicon microchips is still under intensive scientific study as it has proved difficult to obtain a reliable and controllable fabrication technique. So far, the techniques are either costly or suffer from small throughput. Recently, a cost-effective method based on thin-film fracture that can be used as a template for NW fabrication was suggested. Here, a way to integrate NWs between microcontacts is demonstrated. Different geometries of microstructured photoresist formed by using standard photolithography are analyzed. Surprisingly, a very simple "stripe" geometry is found to yield highly reproducible fracture patterns, which are convenient templates for fault-tolerant NW fabrication. Microchips containing integrated Au, Pd, Ni, and Ti NWs and their suitability for studies of conductivity and oxidation behavior are reported, and their suitability as a hydrogen sensor is investigated. Details of the fabrication process are also discussed.

Design Rules for Nanogap‐Based Hydrogen Gas Sensors

“…Such Pd-coated rough Si nanowires are depicted in Figure 3 b. [22] The fracture patterns were found to change as a function of stripe width. Notably, such vertical type sensors exhibit a low detection limit of 5 ppm H 2 in air, along with a short response time.…”

Procedures and Properties for a Direct Nano-Micro Integration of Metal and Semiconductor Nanowires on Si Chips

“…The sensing quality originates from grainy structure of the nanowires which changes their electrical conductivity as a result of change in the nanogaps between the grains. The Pd nanowires were fabricated by the fracture approach which can also be used for hydrogen detection [29].…”

A Novel Nanofabrication Damascene Lift-Off Technique

“…To improve the outcome of the residual deposition and to accelerate the conventional lift-off process, in certain circumstances it is necessary to agitate the sample in an ultrasonic bath filled with a solvent solution. However, such a procedure can lead to the removal not only of the residual material, but also of the fabricated structure, especially when the desired features are very delicate and of nanoscale dimensions [8]. Hence, the lift-off process is often considered to be a trial and error technique, in which optimum process parameters identified with one particular material may not work for another.…”