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Fabricating Nanotube and Nanowire Cross-Point Memory Structures using Electric Fields in Micro-Fluidic Chips

IP.com Disclosure Number: IPCOM000131784D
Publication Date: 2005-Nov-18
Document File: 4 page(s) / 221K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that incorporates micro- and nano-array designs in micro-fluidic chips to control the location of carbon nanotubes (CNTs) and nanowires (NWs) during dielectrophoretic (DEP) alignment and deposition. Benefits include a solution that provides greater fabrication control, yield, and reproducibility.

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Fabricating Nanotube and Nanowire Cross-Point Memory Structures using Electric Fields in Micro-Fluidic Chips

Disclosed is a method that incorporates micro- and nano-array designs in micro-fluidic chips to control the location of carbon nanotubes (CNTs) and nanowires (NWs) during dielectrophoretic (DEP) alignment and deposition. Benefits include a solution that provides greater fabrication control, yield, and reproducibility.

Background

There is a need to fabricate high-density cross-point structures for memory device applications. Currently, the following approaches are used to create the cross-point structures:

§         Aligning the semiconducting nanowires, using the shear force of fluid flow in micro-fluidic channels. The directional deposition is a product of the flow, and the spacing is controlled by the selective deposition on chemically-patterned substrates.

§         Patterning catalyst pads on desired areas and growing nanostructures (CNTs) on the electrodes, hoping a contact is made (i.e. a random process).

General Description

The disclosed method describes a new way to fabricate high-density, cross-point structures for memory applications. The disclosed method uses DEP and micro- and nano-arrays inside micro-fluidic chips to align CNTs and/or NWs into cross-point structures. This allows for the flexible attachment of different bi-stable molecules to act as the switch, prior to alignment/deposition of the final leg of the cross-point structure. Figure 1 shows a schematic of this cross-point structure.

The process uses DEP to align CNTs and/or NWs in the direction of the electric field. The direction of the electric field is determined by the location of electrodes. The alignment and deposition happens at the edges of the electrodes, where there is a concentration of electric field lines. Figure 2 shows a schematic of the electric field lines in a simple electrode structure. Figure 3 shows a SEM of CNT alignment via DEP. A similar alignment is expected for NWs. The CNT and or NW deposition density is augmented by controlling the DEP time and solution concentration. During the deposition, there is no fluid flow in the micro-fluidic chip. The CNT/NW solution is stationary over the electrodes during DEP deposition; the fluid will only flow in the chip when the solutions are changed between the CNT/NW solution, rinsing solution, and solution containing the switching molecule.

 

The next step in the fabrication is the design of the micro- and nano-arrays. The dimension, spacing, and period of the array determines the width, spacing, and period of the cross-point structures. The array structure determines the parameters of the cross-point structure by defining the areas where CNT or NW alignment is possible by DEP. Only the areas between the posts, pillars, or lines of the array (i.e. areas where CNT or NW solutions can flow in the micro-fluidic chip) are where the cross-point structures will be formed. Figure 4 shows a schematic of an array in a micr...