Low temperature chemical vapour synthesis of Cu3Ge thin films for interconnect applications (original) (raw)
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Nanoscale electrical properties of epitaxial Cu3Ge film
Scientific reports, 2016
Cu3Ge has been pursued as next-generation interconnection/contact material due to its high thermal stability, low bulk resistivity and diffusion barrier property. Improvements in electrical performance and structure of Cu3Ge have attracted great attention in the past decades. Despite the remarkable progress in Cu3Ge fabrication on various substrates by different deposition methods, polycrystalline films with excess Ge were frequently obtained. Moreover, the characterization of nanoscale electrical properties remains challenging. Here we show the fabrication of epitaxial Cu3Ge thin film and its nanoscale electrical properties, which are directly correlated with localized film microstructures and supported by HRTEM observations. The average resistivity and work function of epitaxial Cu3Ge thin film are measured to be 6 ± 1 μΩ cm and ~4.47 ± 0.02 eV respectively, qualifying it as a good alternative to Cu.
Effects of copper content and heat treatment on the electrical properties of Ge Te Cu thin films
The mechanism of incorporation of copper in amorphous films of Ge15Te85yx Cu x 0FxF7 at.%. system and the effect of heat treatment are studied by measuring the dc conductivity in the temperature range 150–423 K.. The results indicates that there are two conduction mechanisms. For temperature above 330 K, conductivity exhibits activated behaviour, while in low temperature range Ts150–300 K. conductivity exhibits non-activated behaviour. In the high temperature region, resistance and the activation energy have been calculated. The decrease in the activation energy on addition of Cu has been interpreted according to the Kastner model. In the low temperature region Mott’s parameters have been evaluated and they are decreased with Cu content; the results in this region are interpreted following Mott’s model
Film-thickness effects on the optical and electrical properties of Cu-GeO2 thin cermet films
Journal of Materials Science, 1993
The effect of film thickness on the optical and electrical properties of Cu-30 wt % Ge02-70 wt % thin cermet films prepared by electron-beam deposition at about 10-a Pa and at a substrate temperature of 300 K is reported. The ultraviolet, visible and direct current (d.c.) conductivity results are analysed with the aim of determining the optical band gap, Eopt, the width of the band tails, Ee, and the d.c. thermal activation energy, Ea. It was found that the optical energy gap increases with increasing thickness and that the absorption was due to indirect transitions in k-space. The general feature of the absorption edge remains similar for both unannealed and annealed films, but annealing has the effect of decreasing Eopt. The d.c. conductivity results show that Ea decreases with increasing thickness. From a knowledge of Eopt andEa, a probable model of the electronic band structure in Cu-Ge02 thin films has been suggested.
Physica status solidi, 2016
We investigated the low-temperature Cu-induced polycrystallization (150 °C) of electrodeposited Ge film on a flexible substrate. For a 50 nm-electrodeposited Ge film on a flexible substrate and annealed for 1 h, a Raman shift peak due to Ge-Ge bonding at 299 cm-1 was not observed, but a broad amorphous Ge around 270 cm-1. However, the Ge-Ge bond peak was observed after 5 h of annealing. The crystallization speed of Ge on the flexible substrate was slower than on a quartz substrate. The FWHM value of the Raman shift with respect to electro-deposition current had a minimum value of 9.2.cm-1 at a electrodeposited current of 80 mA. The main XRD observed peaks were Ge(111) at 27° and Ge(102) at 30°. The stress evaluated by Stoney's equation was about 0.5 GPa. However, the stress increased with the electrodeposition current. The stress before and after annealing of 60 mA was weaker than those in the films at a higher electrodeposition current. We propose that the electrodeposition current dependence is related to the deposition rate.
Low-Temperature Hetero-Epitaxial Growth of Ge on Si by High Density Plasma Chemical Vapor Deposition
MRS Proceedings, 2006
ABSTRACTDemand for integration of optoelectronic functionality (e.g., optical interconnects) with silicon complementary metal oxide semiconductor (CMOS) technology has for many years motivated the investigation of low temperature (∼ 450°C) germanium deposition processes that may be integrated in to the back-end CMOS process flow. A common challenge to improving the germanium quality is the thermal budget of the in-situ bake, which is used to reduce defect forming oxygen and carbon surface residues. Typical cleaning temperatures to remove significant concentrations of oxygen and carbon have been reported to be approximately 750°C for thermal hydrogen bakes in standard chemical vapor deposition chambers. Germanium device performance using lower peak in-situ cleans (i.e., ∼450°C) has been hampered by additional crystal defectivity, although epitaxy is possible with out complete removal of oxygen and carbon at lower temperatures.Plasma enhanced chemical vapor deposition (PECVD) is used ...
Applied Surface Science, 2003
Epitaxial growth of Si on SiH 3 CH 3 reacted Ge(1 0 0) using ultraclean hot-wall low-pressure chemical vapor deposition (LPCVD), and the intermixing between Si and Ge during heat treatment has been investigated. By SiH 3 CH 3 reaction at 450 8C, Si and C atomic layers are self-limitedly formed on Ge(1 0 0), and the number of C atoms decreases with increasing heat treatment temperature in the range of 500-700 8C. After such treatment, Si epitaxial growth on the 6 Â 10 13 cm À2 C existing Ge(1 0 0) is achieved at 500 8C. To clarify the interface abruptness, dependence of Ge 3d intensity on the depth are obtained by repetition of X-ray photoelectron spectroscopy (XPS) measurements and wet etching. It is found that the intermixing between Si and Ge during Si epitaxial growth and heat treatment after its growth is suppressed by the existence of C atoms at the heterointerface.
Ge growth over thin SiO2 by UHV–CVD for MOSFET applications
Thin Solid Films, 2008
The growth of germanium by ultra high vacuum-chemical vapour deposition (UHV-CVD) on a thin SiO 2 layer (0.6 nm) formed on Si(001) was investigated by real-time reflection high energy electron diffraction (RHEED), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It was observed that the growth of Ge at 600°C on a 2 monolayers thick SiO 2 (0.6 nm) film remains perfectly coherent with the Si (001) substrate. The mechanism of reduction of SiO 2 is also discussed for higher Ge deposition temperatures. It was found to involve both Si from the substrate and Ge from the gas phase.
Structure and Electrical Properties of Cu/Ge Ohmic Contacts
MRS Proceedings, 1995
Chemistry, crystal structure, interfacial microstructure and electrical characteristics of novel Cu-Ge alloyed ohmic contacts to n-type GaAs with a very low specific contact resistivity ((4–6)×10−7 Ω·cm2 for n∼1×1017 cm−3) were investigated by various methods. The Cu-Ge alloys with a wide range of Ge concentration, from 15 to 40 at %, were prepared by depositing sequentially Cu and Ge layers (or vise versa) onto GaAs substrates at room temperature followed by annealing at 400°C. It is shown that Cu reacts only with Ge to form the ξ and ε1-Cu3Ge phases. The latter has an orthorhombic structure with average lattice parameters: a = 5.301 Å, bo = 4.204 Å, co = 4.555 Å, arising from the parent hexagonal ξ-phase by Cu-Ge ordering along ao. The interface with GaAs is atomically sharp and free from secondary phases. The ε1-Cu3Ge ordered phase which is chemically inert with respect to GaAs, is believed to be responsible for high thermal stability (up to 450°C), interface sharpness, high cont...