Low Temperature Area-Selective Atomic Layer Deposition of NiO, Ni and Pd for Next-Generation Nanomanufacturing

Author
Himamshu Nallan Chakravarthula
Year
2022
Thesis name in original language
Low Temperature Area-Selective Atomic Layer Deposition of NiO, Ni and Pd for Next-Generation Nanomanufacturing
Abstract & Cover

Nickel oxide and palladium are used within various device heterostructures for chemical sensing, solar cells, batteries, etc. There is increasing interest in realizing flexible, low-cost, wearable electronics to enable ubiquitous sensors, next-generation displays, and improved human-machine interfaces. A major hurdle for flexible technology is the development of low temperature fabrication processes for the integration of inorganic devices with polymeric substrates. Here we investigate area-selective atomic layer deposition of NiO performed at 100 °C using bis(N,N'-di-tert-butylacetamidinato)nickel(II) and water on SiO2 and polystyrene. NiO grows two dimensionally and without nucleation delay on oxide substrates but not on SiNx or polystyrene, which require surface treatments such as an Al2O3 buffer layer or O2 plasma treatment to promote NiO nucleation. Additionally, prepatterned sp2 carbon-rich resists inhibit the nucleation of NiO. This way, carbon-free NiO may be patterned. A NiO grid pattern is fabricated as a demonstration. 10 Additionally, thermal reduction of NiO to Ni was explored using H2 (50-300 mTorr) and thermally generated H-atoms (3×10-5 Torr chamber pressure). Due to the relatively high free surface energy of metals, Ni films undergo dewetting at elevated temperatures when solid-state transport is enabled. Reduction of NiO to Ni is demonstrated at 100 °C and below using atomic hydrogen, a temperature low enough to be compatible with organic substrate temperature constraints as well as to avoid significant dewetting. Finally, the area-selective atomic layer deposition of Pd by area-activation is studied. Thermal atomic layer deposition of Pd can only proceed at low temperatures on surfaces that can dissociate the coreactant, H2. Prepatterned Ni functions to catalyze the nucleation of Pd at 100 °C. H-atom reduction of NiO grown by atomic layer deposition can generate an atomically smooth Ni surface, which allows the growth of void-free Pd films. Finally, the area-selective atomic layer deposition of Pd on patterned Ni grid lines is explored 

University
The University of Texas at Austin
(Austin, Tx, USA)
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