Paper TF2-ThM1
Area Selective Deposition from an Aqueous Fog

Thursday, November 10, 2016, 8:00 am, Room 105A

As ULSI technology continues to scale towards the sub-10 nm regime, lithographic patterning and registration to existing features have become increasingly difficult, expensive, and time consuming. Direct patterning or area selective deposition of materials only on desired areas of a substrate has been proposed as a way to overcome these lithographic challenges. Recently, several groups have demonstrated area selective atomic layer deposition (ALD) through approaches such as area deactivation - the use of polymers and self-assembled monolayers (SAMs) to inhibit ALD nucleation. While this work shows promise, alternatives to elevated temperature, vacuum based deposition techniques are desired by the microelectronics, photovoltaics, and display industries. Solution based deposition techniques offer a lower cost, more sustainable approach. Traditional spin-coating, however, is primarily limited to planar substrates and lacks the ability to form uniform films over large surface areas. A number of mist based deposition techniques have attempted to address the limitations of spin coating, but typically suffer from one or more disadvantages such as the requirement of high volatility precursors, uneven mist distribution, complex vapor transport, and/or poor control of film uniformity. A new aerosol based technique overcomes these problems by employing a novel atomizer consisting of two opposing jets located within the deposition chamber. Head-on collision of the opposing jets shears the precursor droplets into a fine mist / fog, allowing the use of low volatility precursors. The uniform generation of mist is scalable for deposition on arbitrarily large substrate areas. In this work we use this method to demonstrate area selective deposition from an aqueous fog at room temperature and pressure.

Aerosol deposition was conducted on a BENEQ ACS 200-101at room temperature and pressure using precursor fog of aqueous based aluminum phosphate inorganic clusters. An octyltrichlorosilane (OTS-8) based SAM with a hydrophobic tail group is used as a growth inhibitor. OTS-8 is patterned on a hydrophilic Si wafer surface. Selective deposition of oxide thin films from an aqueous precursor aerosol fog is achieved with growth occurring only in the hydrophilic regions and not on the areas covered by OTS-8. Smooth films with sharp boundaries are deposited with average surface roughness of less than 1 nm RMS. Deposition selectivity is investigated as a function of pattern size, shape, and half pitch. Overall, room temperature area selective aerosol deposition is shown to be a potentially promising sustainable alternative to AS-ALD for large area electronics.