Selective atomic layer deposition of zirconia on copper patterned silicon substrates using ethanol as oxygen source as well as copper reductant

We report on results on the preparation of thin (<100 nm) aluminum oxide (Al2O3) films on silicon substrates using thermal atomic layer deposition (T-ALD) and plasma enhanced atomic layer deposition (PE-ALD) in the SENTECH SI ALD LL system. The T-ALD Al2O3 layers were deposited at 200 °C, for the PE-ALD films we varied the substrate temperature range between room temperature (rt) and 200 °C. We show data from spectroscopic ellipsometry (thickness, refractive index, growth rate) over 4” wafers and correlate them to X-ray photoelectron spectroscopy (XPS) results. The 200 °C T-ALD and PE-ALD processes yield films with similar refractive indices and with oxygen to aluminum elemental ratios very close to the stoichiometric value of 1.5. However, in both also fragments of the precursor are integrated into the film. The PE-ALD films show an increased growth rate and lower carbon contaminations. Reducing the deposition temperature down to rt leads to a higher content of carbon and CH-species. We also find a decrease of the refractive index and of the oxygen to aluminum elemental ratio as well as an increase of the growth rate whereas the homogeneity of the film growth is not influenced significantly. Initial state energy shifts in all PE-ALD samples are observed which we attribute to a net negative charge within the films.

Download Full-text

Plasma Enhanced Atomic Layer Deposition of Iridium Oxide for Application in Miniaturized Neural Implants

Current Directions in Biomedical Engineering ◽

10.1515/cdbme-2021-2137 ◽

2021 ◽

Vol 7 (2) ◽

pp. 539-542

Author(s):

Nicolai Simon ◽

Maria Asplund ◽

Thomas Stieglitz ◽

Volker Bucher

Keyword(s):

Atomic Layer Deposition ◽

Electrochemical Impedance ◽

Chemical Vapour ◽

Atomic Layer ◽

Iridium Oxide ◽

Silicon Substrates ◽

Neural Implants ◽

Layer Deposition ◽

Low Costs ◽

Deposition Processes

Abstract High quality recording of neuronal activities and electrical stimulation require neurotechnical implants with appropriate electrode material. Iridium oxide (IrOx) is an excellent choice of material due to its biocompatibility, low electrochemical impedance, superior charge injection capacity, corrosion resistance, longevity, and electrochemical stability. Plasma enhanced atomic layer deposition (PE-ALD) and a suitable precursor, like (Methylcyclopentadienyl) (1,5- cyclooctadiene) iridium, could be a promising technique to produce highly conformal and performant IrOx-films at low temperatures and low costs. Various studies have reported the deposition of iridium oxide, but usually at very high temperatures. These processes are not suitable for polymer substrates and limit the use of such post-processing together with active implants. In this work the (Methylcyclopentadienyl) (1,5-cyclooctadiene) iridium(I) ((MeCp)Ir(COD)) precursor was used as a promising approach for depositing IrOx-films using low temperature PE-ALD. This precursor is normally used for chemical vapour deposition processes. First experiments were carried out on silicon substrates at deposition temperatures of 110 C°. The precursor was heated up to 75 °C and oxygen plasma was used as coreactant. The deposited films were analysed with EDX and AFM, showing a smooth surface and a promising ratio between the elements iridium and oxygen.

Download Full-text

Selective Atomic Layer Deposition of TiO2 on Silicon/Copper-patterned Substrates

The Journal of Undergraduate Research at the University of Illinois at Chicago ◽

10.5210/jur.v5i1.7500 ◽

2012 ◽

Vol 5 (1) ◽

Author(s):

A. Jablansky ◽

Jorge I. Rossero A. ◽

G. Jursich ◽

C.G. Takoudis

Keyword(s):

Growth Rate ◽

Atomic Layer Deposition ◽

Exposure Time ◽

Linear Growth ◽

Atomic Layer ◽

Linear Growth Rate ◽

Silicon Substrates ◽

Oxidizing Agent ◽

Microelectronic Devices ◽

Layer Deposition

As microelectronic devices shrink, thinner diffusion barrier layers are needed to separate the copper and silicon substrates while leaving the copper vias open for conduction. Selective atomic layer deposition (ALD) of titanium dioxide(TiO2), a good barrier layer, onto silicon was studied by minimizing the exposure time to air of these substrates immediately before deposition. The minimized exposure time mimicked industrial conditions, where waiting before deposition is costly. Tetrakis(diethylamido)titanium (TDEAT) was used as the precursor, and water was the oxidizing agent. TDEAT was first deposited on silicon wafers using ALD to verify a steady, linear growth rate reported in the literature, and the measured rate of 0.9 ± 0.1 Å/cycle is consistent with values previously reported. Minimized exposure to air had no effect on the growth rate of TiO2 on silicon, and the effect on copper has yet to be determined.

Download Full-text

Atomic layer deposition of zirconium oxide on copper patterned silicon substrate

The Journal of Undergraduate Research at the University of Illinois at Chicago ◽

10.5210/jur.v7i1.7526 ◽

2014 ◽

Vol 7 (1) ◽

Author(s):

J. Parulekar ◽

S. Selvaraj ◽

C.G. Takoudis

Keyword(s):

Growth Rate ◽

Atomic Layer Deposition ◽

Copper Oxide ◽

Metallic Copper ◽

Atomic Layer ◽

Copper Surface ◽

Silicon Surfaces ◽

Silicon Substrates ◽

Copper Surfaces ◽

Layer Deposition

Atomic layer deposition (ALD) was performed on copper patterned silicon substrates using zirconium precursor and ethanol as both an oxygen source and reducing agent. Ethanol targeted copper oxide formed on the copper surface, reverting it back to metallic copper. Selective ALD (SALD) of metal oxides on silicon surfaces over copper surfaces has been demonstrated up to 2-3 nm, though the process seems to lose its selectivity afterwards. We strive to maintain selectivity to thicker films by stepping away from conventional ALD processes utilizing oxidants. From previous studies with HfO2 and TiO2 SALD, we speculate that the oxidation of copper to copper oxide spoils selectivity. In this present study, we carried out oxidant-free ALD by using ethanol as a co-reactant solely on the silicon portion of these substrates. This process will occur in-situ every 20-30 ALD cycles for ALD of ZrO2. As expected, reduced ALD growth rate was observed with ethanol compared to that of water or ozone, with a growth rate of about 0.04 nm/cycle on the silicon portion of the substrate.

Download Full-text