Molecular Mechanism of Selective Al2O3 Atomic Layer Deposition on Self-Assembled Monolayers

Abstract

Area-selective atomic layer deposition (AS-ALD) of insulatingmetallicoxide layers could be a useful nanopatterning technique for makingincreasingly complex semiconductor circuits. Although the alkanethiolself-assembled monolayer (SAM) has been considered promising as anALD inhibitor, the low inhibition efficiency of the SAM during ALDprocesses makes its wide application difficult. We investigated thedeposition mechanism of Al2O3 on alkanethiol-SAMsusing temperature-dependent vibrational sum-frequency-generation spectroscopy.We found that the thermally induced formation of gauche defects inthe SAMs is the main causative factor deteriorating the inhibitionefficiency. Here, we demonstrate that a discontinuously temperature-controlledALD technique involving self-healing and dissipation of thermallyinduced stress on the structure of SAM substantially enhances theSAM's inhibition efficiency and enables us to achieve 60 ALDcycles (6.6 nm). We anticipate that the present experimental resultson the ALD mechanism on the SAM surface and the proposed ALD methodwill provide clues to improve the efficiency of AS-ALD, a promisingnanoscale patterning and manufacturing technique.