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NIST presents a method for in-plane formation of nanochannels in semiconductor materials. Using this approach location, length, width, and end points of a nanochannel can be controlled. Nanochannels are formed by a metal-catalyzed surface etch reaction which is propelled by introduction of oxygen or water vapor to the heated surface of a semiconductor. During the heating cycle, metal catalyst nanoparticles such as Au and the semiconductor react forming solid or liquid alloys. The dissolved semiconductor in an Au particle reacts with the water or oxygen at the particle surface and becomes oxidized. The oxidized species depart from the Au particle surface. Iteration of dissolution of semiconductor in Au particle and its escape results in formation of surface-directed nanochannels.

The figure below shows a nanoduct that includes a nanochannel disposed on a semiconductor substrate in which panel A shows a perspective view, and panel B shows a top view. The components are the semiconductor substrate (2), nanoduct (4), nanoduct sidewalls (6, 8, and 10), duct wall (12), aft wall (14), and fore wall (16).


A process for making a nanoduct includes: disposing an etchant catalyst on a semiconductor substrate including a single crystal structure; heating the semiconductor substrate to an etching temperature; introducing an oxidant; contacting the semiconductor substrate with the oxidant in a presence of the etchant catalyst; anisotropically etching the semiconductor substrate by the etchant catalyst in a presence of the oxidant in an etch direction that is coincident along a crystallographic axis of the semiconductor substrate; and forming the nanoduct as the etchant catalyst propagates along a surface of the semiconductor substrate during anisotropically etching the semiconductor substrate, the nanoduct being crystallographically aligned with the crystallographic axis of the semiconductor substrate.


Formation of single or arrays of nanochannels with sub-lithographic resolution at a wafer scale is not a routine practice at the present time. Current methods for fabrication of nanofluidic devices require use of high-resolution photolithography and rigorous chemical etch methods, which greatly add to the manufacturing cost for mass production or commercial use. Formed nanochannels must be sealed to allow transporting fluids, which adds to the complexity of the process. This method is a simple approach that allows rapid and controlled formation of nanochannels with controlled dimensions at specific sites in a scalable and predictable fashion. Also, it allows sealing nanochannels during their etch process and on-chip integration of nanofluidic devices to other device components such as a transistor or a photonic circuit.

Nikoobakht, Babak
Patent Number: 
Technology Type(s): 
Analytical Chemistry, Manufacturing, Materials for Electronics, Biomaterials, Chemical Science, Electronics,
Internal Laboratory Ref #: 
Patent Issue Date: 
September 11, 2018
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