Pascal Doppelt

Focused electron beam induced deposition of gold

Codeposition of hydrocarbons is a severe problem during focused electron beam writing of pure metal nanostructures. When using organometallic precursors, a low metal content carbonaceous matrix embedding and separating numerous nanosized metal clusters is formed. In this work, we present a new and easy approach to obtain high purity gold lines: the use of inorganic PF3AuCl as a precursor. Electrical resistivities as low as 22 µOhms cm at 295 K (ten times the bulk Au value) were obtained. This is to our knowledge the best value for focused electron beam deposition obtained from the vapor phase so far. No special care was taken to prevent hydrocarbon contamination. The deposited nanostructure consists of gold grains varying in size and percolation with beam parameters.

Self-assembled subnanolayers as interfacial adhesion enhancers and diffusion barriers for integrated circuits

Preserving the structural and functional integrity of interfaces and inhibiting deleterious chemical interactions are critical for realizing devices with sub-50 nm thin films and nanoscale units. Here, we demonstrate that ∼0.7-nm-thick self-assembled monolayers (SAMs) comprising mercapto-propyl-tri-methoxy-silane (MPTMS) molecules enhance adhesion and inhibit Cu diffusion at Cu/SiO2 structures used in device metallization. Cu/SAM/SiO2/Si(001) structures show three times higher interface debond energy compared to Cu/SiO2 interfaces due to a strong chemical interaction between Cu and S termini of the MPTMS SAMs. This interaction immobilizes Cu at the Cu/SAM interface and results in a factor-of-4 increase in Cu-diffusion-induced failure times compared with that for structures without SAMs.

Electrodes for carbon nanotube devices by focused electron beam induced deposition of gold

Individual carbon nanotubes (CNTs) often occur in randomly dispersed two-dimensional as well as three-dimensional configurations that make device fabrication difficult. Making electrical contact to such CNTs is of practical interest. To this end, we make contact to individual metallic single-walled carbon nanotubes (SWNTs) using the focused electron-beam-induced deposition (FEBID) of pure gold. The SWNTs are grown by chemical vapor deposition on a flat substrate, and the gold leads are made through FEBID using inorganic metallic precursor gas, chloro(trifluorophosphine)gold(I), or AuClPF3, in a high vacuum scanning electron microscope. The same scanning electron microscope is also used to image carbon nanotubes, allowing for simultaneous alignment. We find equivalent one-dimensional resistivities for the SWNTs of 10–15kΩ∕μm for both FEBID gold leads and leads deposited using conventional electron-beam lithography (EBL) and thermal evaporation of gold, suggesting similarly low contact resistances. We use e...

Vanadium Oxide Films Synthesized by CVD and Used as Positive Electrodes in Secondary Lithium Batteries

Vanadium oxide films were synthesized by chemical vapor deposition from pure or diluted VO(OC 3 H 7 ) 3 precursor. An annealing process at 500°C was required to obtain crystallized V 2 O 5 . X-ray diffraction patterns have pointed out the influence of the operating conditions for the vanadium oxide deposition on the crystallites sizes. No significant difference in the roughness factor was observed by atomic force microscopy measurements before and after annealing at 500°C. As-deposited V 6 O 13 films were also directly obtained by changing the operating conditions. The insertion/deinsertion of Li + into the host structure was investigated in 1 M LiClO 4 -propylene carbonate. V 2 O 5 films exhibit low irreversible capacity and high cyclability even for a deep lithium insertion ratio; in addition, only small amounts of γ-phases were formed during cycle life at low potential without significant effects on its electrochemical performance. After subsequent cycles between 3.8 and 2.2 V vs. Li/Li + . the reversible capacity is found to be 250 mAh g -1 (y 1.65) close to the theoretical one. V 6 O 13 films exhibit reversible capacity of about 410 mAh g -1 (y 7.9).

Organic light-emitting transistors using concentric source/drain electrodes on a molecular adhesion layer

Bottom-contact tetracene light-emitting transistors employing a mercaptosilane derivative self-assembled monolayer as adhesive between gold concentric interdigitated source/drain electrodes and SiO2 gate dielectric are described. Devices that employ the mercaptosilane adhesive have a higher mobility and electroluminescence compared to those employing a standard metallic adhesive. This is rationalized in terms of the large, well interconnected grains found in tetracene films deposited on substrates using the mercaptosilane adhesive. Our work represents a step forward in the understanding of physical processes at semiconductor/metal and semiconductor/dielectric interfaces in organic devices.

Comparative Study of Cu Precursors for 3D Focused Electron Beam Induced Deposition

The copper precursors bis-hexafluoroacetylacetonato-copper Cu ~hfac) 2 , vinyl-trimethyl-silane-copper~I!-hexafluoroacetylacetonate ~hfac!Cu~VTMS!, 2-methyl-1-hexen-3-yne-copper-hexafluoroacetylacetonate ~hfac!Cu~MHY!, and dimethylbutene-copper~I!-hexafluoroacetylacetonate ~hfac!Cu~DMB! are compared with respect to deposition rates and metal content obtained by focused electron beam induced deposition. Exposure was performed with 25 keV electrons in a Cambridge S100 scanning electron microscope equipped with a lithography system. Tip deposition rates increase with increasing precursor vapor pressure and range between 47 nm/s for ~hfac!Cu~DMB! to about 4 nm/s for Cu~hfac) 2 . A decay of deposition rates with time, i.e., tip length, is observed. Electric 4-point measurements indicate an insulating behavior of deposited lines for all precursors. In contrast, Cu contents of up to 45-60 atom % were found by Auger electron spectroscopy in thin rectangular deposits using ~hfac!Cu~DMB! and ~hfac!Cu~VTMS! as precursors. A discussion in terms of monolayer coverage, completeness of precursor molecule dissociation, and precursor stability is presented.

Evaluation of (hfac)Cu(MHY) for Cu CVD

Copper deposition using (hfac)Cu(MHY) (Gigacopper®) for interconnections metallization by Cu CVD is presented. We compared it to (hfac)Cu(VTMS) (Cupraselect®) in terms of deposition rate, specific resistivity and uniformity. Gigacopper® appears to give a higher deposition rate than Cupraselect® and about the same specific resistivity. Water addition is a critical point. It permits improved uniformity and specific resistivity provided it is added during the nucleation step in a very precise volume. We also studied the influence of other parameters, such as precursor flow rate and reactor pressure, on the film deposition. The use of Cu CVD as seed layer for Cu ECD depositions was also explored on full sheet wafers. Adhesion can be greatly enhanced by a specific anneal procedure with a slow cool down to limit stresses in the film.

Static Vapor Pressure Measurement of Low Volatility Precursors for Molecular Vapor Deposition Below Ambient Temperature

Keywords: [NRG] Note: \\Atlantis\MAD\MAD public\Publi Present Conferences\Publications\printed papers\2001 : NRG Ohta 2001 115 Reference LOA-ARTICLE-2001-016doi:10.1002/1521-3862(200101)7:1 3.0.CO;2-Y Record created on 2009-07-20, modified on 2017-05-10

Mineral precursor for chemical vapor deposition of Rh metallic films

Di-μ-chloro-tetrakis(trifluorophosphine)dirhodium(I)((PF3)2RhCl)2, was synthesized by using the method of Bennett and Patmore, and was purified twice by sublimation. The decomposition reaction of the complex studied by Fourier transform IR spectroscopy in the vapor phase showed that no volatile species except the complex and PF3 were present in the gas phase. We used this mineral precursor to obtain metallic Rh films by chemical vapor deposition under very mild conditions (T<200 °C, P=3−10 Torr) on Pyrex glass slides or NaCl substrates. The smooth Rh films obtained, with a mirror-like aspect, have been characterized by X-ray diffraction (indicating a crystalline nature, f.c.c., Fm3m with a=3.806(2) A), transmission electron microscopy (800 A×50 A×50 A single crystals are present) and X-ray photoelectron spectroscopy. Neither P nor F atoms could be detected, but a significative amount of Cl atoms was present in the films identified as RhCl3.

Gold CVD Using Trifluorophosphine Gold(I) Chloride Precursor and Its Toluene Solutions

The chemical vapor deposition (CVD) of gold using trifluorophosphine gold(I) chloride, a simple and volatile inorganic precursor, is presented. Both solid precursor and its toluene solutions were used as starting materials. With the solid precursor placed in a simple bubbler, adhesive and continuous gold thin films were grown on Ta/TaN/SiO 2 /Si substrates with a growth rate of only 8 A min -1 . However, with a liquid delivery system using 2.5% precursor solution in toluene with a volume rate of 0.3 mL min -1 , a growth rate of 200 A min-1 was achieved. Both H 2 and N 2 were used as carrier gas, but only in the case of H 2 were compact and highly pure 100-200 nm thick gold films grown on Ta/TaN/SiO 2 /Si at deposition temperature as low as 110°C. The dependence of the deposition process and characteristics of gold deposited films, such as morphology, microstructure, and chemical composition, on deposition temperature and the nature of the carrier gas (N 2 or H 2 ) was also investigated.