Hybrid Films Deposition for Nanochannel Membranes with Functional Surfaces

Thin film deposition is one of the most significant issues in the fabrication of nano structures. Especially it is difficult to achieve conformal films on high-aspect ratio nanostructures, such as nanochannel membranes. Though there are various thin film deposition techniques, atomic layer deposition (ALD) has attracted due to its extreme surface conformality and excellent thickness controllability. Because ALD is a chemical gas phase thin film deposition method based on sequential and self-saturating surface reactions, it can be used for coating of nano structures with high-aspect ratio.

Sputtering process is one of the popular film deposition techniques due to its relative simplicity of process and fast deposition speed. However, film depositions by sputtering technique are less conformal compared to those by ALD, because of ions directionality sputtered by plasma. Therefore it is difficult to form films on the surfaces perpendicular to substrate by sputtering process.

However, if ALD and sputtering techniques are combined, hybrid thin films deposition which different films are deposited on selectively different surfaces (eg. surfaces perpendicular and parallel to substrate). In this poster, I will present the results of hybrid films deposition on nanochannel membranes with high-aspect ratio. For different functionalities (hydrophilicity and hydrophobicity) of surfaces, Al2O3 and Pt films were grown on nanochannel membranes. Al2O3 films deposition on the vertical surfaces (inner surfaces of nanochannels) was controlled precisely in nanometer scale by using ALD process. Pt films were formed on horizontal surfaces (outer surfaces of nanochannels) by using DC magnetron sputtering. In addition, I will also present the ionic seperation in NaCl solution using fabricated nanochannel membranes by hybrid deposition process and using electrcal bias on Pt films.