Selective and smooth dielectric-on-dielectric was achieved by water-free single-precursor chemical vapor deposition (CVD) processes with the help of aniline passivation. Aniline selective passivation was demonstrated on W surfaces in preference to SiO 2 at 250, 300, and 330 °C. After aniline passivation, selective HfO 2 , Al 2 O 3 , and TiO 2 were deposited only on the HF-cleaned SiO 2 surface by water-free single-precursor CVD using hafnium tert-butoxide Hf(O t Bu) 4 , aluminum-tri-sec-butoxide (ATSB), and titanium isopropoxide Ti(O i Pr) 4 as the precursor reactants, respectively. Hf(O t Bu) 4 and Ti(O i Pr) 4 single-precursor CVD was carried out at 300 °C, while the ATSB CVD process was conducted at 330 °C. HfO 2 and Al 2 O 3 nanoselectivity tests were performed on W/ SiO 2 patterned samples. Transmission electron microscopy images of the W/SiO 2 patterned samples after deposition demonstrated nanoselectivity and low surface roughness of HfO 2 and Al 2 O 3 deposition on the SiO 2 regions only.
Highly selective and smooth TiO 2 /Al 2 O 3 and HfO 2 /Al 2 O 3 nanolaminates were deposited by water-free pulsed chemical vapor deposition (CVD) at 300 °C using titanium isopropoxide (Ti(O i Pr) 4 ) and hafnium tertbutoxide (Hf(O t Bu) 4 ) with trimethylaluminum (TMA). TMA was found to be the key factor for enhancing nucleation selectivity on SiO 2 or Si versus SiCOH (hydrophobic, nonporous low k dielectric). With precise dosing of TMA, selective nucleation of TiO 2 /Al 2 O 3 and HfO 2 /Al 2 O 3 nanolaminates was achieved and smoother films were formed with higher selectivity compared to single precursor TiO 2 and HfO 2 CVD. The selectivity of TiO 2 /Al 2 O 3 nanolaminate deposition increased from 34 to 44 (deposition on Si vs SiCOH), while RMS roughness of the film of Si decreased from 2.8 to 0.38 nm. The selectivity of HfO 2 /Al 2 O 3 deposition increased from 14 to 73, while the RMS roughness of HfO 2 /Al 2 O 3 on Si was maintained at a similar value of 0.78 nm. Deposition of water-free pulsed CVD TiO 2 /Al 2 O 3 and HfO 2 /Al 2 O 3 nanolaminates was conducted on a Cu/SiCOH patterned sample to study their nanoselectivity. Transmission electron microscopy images of the Cu/ SiCOH patterned sample demonstrated that highly selective and smooth TiO 2 /Al 2 O 3 and HfO 2 /Al 2 O 3 nanolaminates can be formed on a nanoscale pattern.
A new plasma processing-based methodology for enhancing the streaming potential (V s ) that may be obtained in electrokinetic flows for a given pressure gradient over a silicon surface-based microchannel is indicated. The dependence of the V s on both the surface zeta potential and the electrolyte slip length was carefully determined through a series of experiments involving the variation of CF 4 -and Ar-based plasma parameters, incorporating pressure, exposure time, and power. It was determined through analytical estimates that, while the zeta potential is always increased, the slip length may be diminished under certain conditions. A record value of ∼0.1 mV/Pa was obtained using CF 4 plasma at 500 W, 10 mTorr, and 300 s of exposure. The implications of the work extend to the investigation of whether smooth surfaces may be effective for generating large V s 's for new modalities of electrical voltage sources in microfluidics-based applications.
The resistivity of halogen-free atomic layer deposition (ALD) TiN thin films was decreased to 220 μΩ cm by combining the use of a high-thermal stability nonhalogenated Ti precursor with a highly reactive nitrogen source, anhydrous hydrazine (N 2 H 4 ). TDMAT [tetrakis (dimethyl-amino)titanium], TDEAT [tetrakis(diethylamido)titanium], and TEMATi [tetrakis (ethylmethyl-amido)titanium] were compared to TiCl 4 as precursors for ALD TiN using N 2 H 4 as a coreactant. By minimizing the pulse length of the Ti-source precursor and optimizing the deposition temperature, the resistivity of TiN thin films deposited using these precursors was reduced to 400 μΩ cm for TDMAT (at 350 °C), 300 μΩ cm TDEAT (at 400 °C), and 220 μΩ cm for TEMATi (at 425 °C) compared to 80 μΩ cm for TiCl 4 (at 500 °C). The data are consistent with the lowest resistivity for halogen-free ALD corresponding to the organic precursor with the highest thermal stability, thereby allowing maximum ALD temperature. After optimization, TiN thin films were grown in horizontal vias, illustrating conformal and uniform TiN using both TiCl 4 and TEMATi in horizontal vias in patterned substrates.
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