1,721,038 research outputs found
Metallization and nanostructuring of semiconductor surfaces by galvanic displacement processes
No full textThe deposition of metals on semiconductors encompasses a broad range of technologically important processes, with applications ranging
from electronic devices to chemical sensors. Recent years have witnessed a surge of research activities in galvanic displacement processes on
semiconductor substrates. After a brief review of the fundamental aspects underlying galvanic displacement processes on semiconductor surfaces,
this paper discusses applications to micro- and nanoscale devices, including schemes developed for the metallization and nanopatterning of
semiconductor substrates with high selectivity and with optimal interfacial properties
Selective Deposition of Thin Copper Films onto Siliconwith Improved Adhesion
No full textA novel copper deposition method has been developed to plate silicon surfaces. Continuous copper films are obtained galvanically
on p- or n-type, single- or polycrystalline silicon. The films possess homogeneous structure, smooth surface, and improved adhesion
to the substrate. The plating bath comprises an aqueous solution containing a copper compound, ascorbic acid, ammonium fluoride,
and an antistress agent. With this process, the use of seed layers to improve adhesion between metal and semiconductor is avoided
Gold deposition by Galvanic displacement on semiconductor sufraces: effect of substrate on adhesion
No full textThin gold films are grown on Si and Ge substrates by galvanic displacement from fluoride-containing solutions.
The physical and chemical properties of the metal-semiconductor interface are characterized by a variety of
techniques, including photoelectron spectroscopy, atomic force microscopy, and electron microscopy. Displaced
gold films exhibit strong adhesion to germanium substrates but not to silicon. This behavior is explained by
the presence of a chemical bond at the Au-Ge interface, which is not observed in the Au-Si system. The
implications of these findings for semiconductor metallization by galvanic displacement methods are discussed
Selective metallization of silicon micromechanical devices
No full textA new wet process for selective copper deposition on silicon surfaces is employed to achieve conformal metallization of silicon
micromechanical devices. The method is based on galvanic displacement of the metal from a fluoride-containing bath. The plating
bath also comprises a complexing agent, a surfactant and an anti-stress additive. Surface passivation of the displaced Cu film is
effected by dodecanethiol self assembled monolayer coating. This surface passivation is found effective in reducing adhesion of
micro-electromechanical systems
Adhesion evaluation of immersion plating copper films on silicon by microindentation measurements
No full textAdhesion of copper films on silicon is investigated by microindentation measurements. Load–displacement tests with loads in
the range of 1–1000 mN are performed on immersion plating copper films deposited on Si(100) from fluoride containing
solutions, with or without adhesion-promoting additives. The results are analyzed with the aid of a composite hardness model for
soft films on hard substrates. The composite Vickers microhardness is influenced by the adhesion of the copper film to the
substrate: stronger adhesion corresponds to higher composite hardness and more extended deformation zone at the filmysubstrate
interface. Thus, microhardness measurements provide a useful way to quantify the effect of solution additives (such as ascorbic
acid or sodium sulfite) and heat treatment on copper film adhesion, and to rank additives accordingly
Magnetic micromechanical structures based on CoNi electrodeposited alloys
No full textElectrodeposited CoNi magnetic microstructures compatible with silicon microfabrication
technology have been developed using a sulfamate acidic bath, as an alternative to a less
environmentally friendly chloride bath. The galvanostatic electrodeposition in the formulated
electrolyte allows the deposition of cobalt-rich CoNi films and microstructures defined by
photoresist at high deposition rates. Microstructures are adherent to the substrate, with a good
lateral definition and resistance to the wet etching for the release of the sacrificial layer. The
released structures respond to applied magnetic fields and no breakage occurred during large
deformation
Selective deposition of gold nanoclusters on silicon by a Galvanic displacement process
No full textGold nanoclusters are deposited selectively on silicon substrates by galvanic displacement from reversed
micelle microemulsions. The water-in-oil system investigated comprises an organic phase (n-heptane), a
surfactant (AOT), and an aqueous solution of hydrofluoric acid and metallic ions. X-ray diffraction and scanning
electron microscopy are employed to investigate the correlation between the nominal size of the reversed
micelles and the size of the metal clusters formed on the silicon substrate. The measured gold cluster radius is in
good quantitative agreement with nominal micelle radius over a wide range of cluster size and deposition time
Nanometer-thin titania films with SAM-level stiction and superior wear resistance for reliable MEMS performance
No full textMost MEMS devices involving contacting surfaces suffer from stiction and wear. While the development of self-assembled monolayer (SAM)-based processes has virtually eliminated stiction, wear remains a serious reliability issue. In this paper, the use of titania ultrathin films as a means to reduce both stiction and wear is reported. Atomic layer deposition (ALD) is used for the film growth in order to ensure a uniform and conformal coating, effectively encapsulating the released polysilicon microelectromechanical systems (MEMS) devices. The application of 10-nm thin titania coating is shown to result in improved reliability of test microdevices. To further improve reliability, a vapor phase SAM coating is applied to TiO2 encapsulated micromachines. Results on the tribological properties of both TiO2and SAM coated TiO2-encapsulated microdevices are presented
Electrochemical fabrication of supported Ni nanostructures through transferred porous anodic alumina mask
No full text- …
