Vapor Phase Deposition of Self-Assembled Monolayers as a Resist Towards Area-Selective Atomic Layer Deposition

Junsic Hong
Abstract & Cover

Atomic layer deposition (ALI)) is gaining attention as a promising method for depositing high quality, conformal, ultra thin films used in the fabrication of advanced microelectronic devices. Atomic layer deposition relies upon self-terminating surface reactions that limit the growth in most cases to no more than one atomic layer at a time. Since the ALE) pmess is very sensitive to surface characteristics, by modifying the substrate, we can achieve patterned deposition of thin films that can be useful for semiconductor processing. The ability to perform area selective ALD would provide a number of benefits such as a Suction in the cost and number of process steps required for pattern-wise deposition of materials, elimination of possible substrate and device damage induced by the traditional etching of thin films, and the ability to directly pattern materials that are difficult to etch. We have explored the possibility of using vapor phased deposited self-assembled monolayers as a blocking layer to develop area selective atomic layer deposition techniques (AS-ALD). 
We have modified Si surfaces with several types of alkoxy- or chlorosilane-based monolayers which have different head groups and backbone chain lengths. We have varied several reaction parameters such as temperature, pressure and trace amount of water to optimize each self-assembled monolayer forming process. After completing the optimization of vapor delivered SAMs to get ordered hydrophobic surfaces, area-selectivity of modified samples towards ALD was investigated by X-ray photoelectron spectroscopy. We found that deposition of H102 and Pt can be blocked effectively, achieved by deactivation of Si02 substrates by attaching octadecyltrichlosilane (ODTS) through vapor phase deposition over 2 day's silylation exposure. Also, we have successfully blocked the ALD process by several other organic molecules adsorbed on the surfaces. To investigate the characteristics of self-assembled monolayers by the vapor delivery method in more detail, several analytical techniques including, ellipsometry, water contact angle analysis, and multiple internal reflection Fourier transform infrared (MIR-FTIR) spectroscopy have been used We found that to block the substrate from the ALD precursors, a well ordered, densely packed structure is necessary.

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Stanford Libraries
Stanford University
(Stanford, USA)
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