Electroless Methods Research Articles

Fabrication of conductive metallized nanostructures from self-assembled amphiphilic triblock copolymer templates: Nanospheres, nanowires, nanorings

Various metallized nanostructures (such as rings, wires with controllable lengths, spheres) have been successfully fabricated by coating metallic nanolayers onto soft nanotemplates through simple electroless methods. In particular, bimetallic nanostructures have been obtained by using simple methods. The multiple functional polymeric nanostructures were obtained through the self-assembly of polystyrene/poly(4-vinyl pyridine) triblock copolymer (P4VP-b-PS-b-P4VP) in selective media by changing the common solvent properties. By combining field emission scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) characterization, it was confirmed that polymer/metal and bimetallic ([email protected]) core–shell nanostructures could be achieved by chemical metal deposition method.

Microwave-assisted deposition of uniform thin gold film on glass surface

A microwave-assisted method for rapid deposition of continuous gold films on glass substrates has been developed. Under microwave irradiation, gold nanoparticles in colloidal solutions were shown able to assemble on the naked substrates to form a gold monolayer within minutes. Images obtained by AFM revealed that the monolayer formed on the naked glass surface was much the same as that formed on the glass substrates pre-silanized with (3-aminopropyl)-trimethoxysilane. With this monolayer as seeds, further deposition of gold metal on the surface was thus possible and the thickness of the deposited gold was time-dependent as in the case of normal electroless plating . The sum time for preparing a 50-nm gold film on glass was about 15 minutes, much shorter than the existed electroless methods. Electrochemical experiments showed that the prepared gold films were continuous and can be used as stable electrodes able to sustain several hundreds of redox circulation. The quality of the films were also verified by surface plasmon resonance imaging (SPRI) studies and quite sharp pictures of protein dots were obtained, showing a smooth gold surface and proper film thickness were prepared.

An Investigation of Tribological Properties of CN and TiCN Coatings

Today the tool industry on a worldwide basis uses hard, wear-resistant, and low-friction coatings produced by different processes such as electrochemical or electroless methods, spray technologies, thermochemical, chemical-vapor deposition (CVD), and physical vapor deposition (PVD). In the current work, two different coatings, nitrocarburized (CN) and titanium carbonitride (TiCN) on M2-grade tool steel, were prepared by commercial diffusion and PVD techniques, respectively. Properties such as thickness, roughness, and hardness were characterized using a variety of techniques, including glow-discharge optical emission spectrometry (GD-OES) and scanning electron microscopy (SEM). A crossed-cylinders wear-testing machine was used to investigate the performances of both coatings under lubrication. The effect of coatings on the performance of lubricants under a range of wear-test conditions was also examined. Degradation of lubricants during tribological testing was explored by Fourier transform infrared (FTIR) spectroscopy.

Electroless processes for micro- and nanoelectronics

Electroless deposition of metals has many applications in micro- and nanotechnologies. Currently, electroless Cu, Co, Ni, Ag and their alloys are used as materials for interconnects and packaging applications for ultralarge-scale integration (ULSI) as well as for microelectro-mechanical systems (MEMS). Electroless methods offer high-quality ultrathin films that are compatible with high-resolution patterns such as sub-100 nm interconnects, contacts and via contacts for ULSI and in high aspect ratio structures for MEMS. In this paper, we present an overview of electroless methods for microtechnologies applications. We also present Cu, Ag, and Co alloys that are designed to improve performance and reliability of the pure metals. Next, we present new concepts of electroless deposition methods that will be useful for nanotechnologies. We explore the possibility to use electroless methods that can be combined with self-assembly of organic compounds such as proteins to form metallic interconnect network. Silver deposition on organic substrates is described as a novel approach to produce high-quality Ag coating on features with 1–10 nm critical dimensions.

Electroless and sputtered silver–tungsten thin films for microelectronics applications

Thin silver-tungsten (Ag-W) films have been deposited on Si and SiO2 substrates by electroless (El) and ion-beam sputtering (IBS) methods and their morphology was studied by optical and atomic force microscopy. Adding tungsten into the silver film significantly improved its corrosion stability, electrical, optical and mechanical properties. TEM microstructure investigation shown that W is introduced into Ag film in the form of WO3. In this paper we compare the resistance, reflectance and morphology, as determined by atomic force microscopy, of Ag-W films deposited by El and IBS methods for microelectronics application. Finally we present results of the Ag-W films study as barrier for silver metallization by MOS capacitors measurements. The capacitors exhibited almost ideal C-V high frequency characteristics and flat band voltage near to zero. The generation life-time (τ) and the recombination surface velocity (s) were of the same order of those for similar structures with Cu, Co and Al metallization. Those results indicate that Ag-W layers are MOS technology compatible and can be used in microelectronics as a new interconnect and metallization material.

Improvement of the electrochemical behaviour of AlN films produced by reactive sputtering using various under-layers

Abstract Aluminium nitride films were deposited by reactive sputtering on steel substrates (H11) with the aim of realising anti-corrosion coatings. The porosity of the films combined with their inadequate thickness cause the good initial corrosion resistance of the samples to decrease drastically during immersion time in a 0.5 M NaCl solution. In order to create a corrosion barrier between AlN and steel, three types of under-layers were investigated: nickel under-layers (with a thickness of about 10 μm) deposited by both electrochemical and electroless methods, and titanium under-layers (with a thickness of about 1 μm) obtained by sputtering. The structure and morphology of the samples were studied from X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) observations. Electrochemical impedance spectroscopy (EIS) tests versus immersion time were carried out in a 0.5 M NaCl solution in order to compare their corrosion resistance. It appears that AlN/electroless nickel shows the best corrosion resistance, whereas the AlN/electrochemical nickel and AlN/titanium samples are almost in the same range.

Integrated electroless metallization for ULSI

Abstract In this paper, we present a novel copper interconnect scheme where conducting, barrier and capping layers are deposited by electroless methods. Electroless copper deposition has been demonstrated for sub-0.25 μm metallization on large silicon wafers. In this paper, we extend the use of electroless deposition for the layers under and above the copper. After a short overview of electroless copper and barriers deposition we describe some of the current process modules and the properties of the thin films. Next we review the individual layer properties, describe their integration, and discuss the highlights and problems of the integration of copper, barriers, and capping layers, all deposited by electroless methods. The integrated process features deposition from an aqueous solution of copper and CoW alloys. The metals deposition is due to an electrochemical oxidation-reduction reaction that takes place on the liquid-solid interface. Electroless deposition is autocatalytic and the interconnect materials themselves can serve as seeds for some deposition solutions. In some cases, surface activation is required to initiate the autocatalytic process. We will discuss the issues of the seed layer and will present both ‘wet’ and ‘dry’ seeding methods. The deposition of both copper and the barrier layers is very conformal and we assume that the deposition rate is surface-reaction limited. In addition, we present recent results of the barrier material properties and experimental results of the fully integrated structure with and inlaid-copper technology.

Electro/electroless deposition and characterization of CuIn precursors for CIS (CuInSe 2) films

CuIn (CI) precursors for growing CuInSe 2 (CIS) thin films were deposited and characterized. CI precursors were formed by using electrodeposition and electroless methods. In electrodeposition, CI precursors were formed by sequential deposition of Cu In and In Cu . In electroless deposition, the CI precursor was formed by co-deposition. The CI precursors were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). Initial results on the selenization of the precursors indicated that CuIn (electroless), Cu In and In Cu configurations are suitable for forming device quality CIS films. The major phases in the precursors were found to be Cu 11 In 9 and elemental In, which may lead to the formation of the In-rich CIS phase (CuIn 2 Se 3.5 , JCPDS 35-1349) during sintering in argon at lower temperatures. It was found that the stoichiometric CIS phase (CuInSe 2 , JCPDS 40-1487) is formed by selenization of the precursors at temperatures higher than 500°C.

Electroless NiP processing for hybrid integrated circuits

Abstract Electroless methods for depositing conductive layers on insulating materials can be used in producing hybrid integrated circuits (HIC's), as alternatives to the evaporation and sputter deposition techniques. Compared with these techniques, electroless procedures are in general relatively simple and it is easy to metallize holes in substrates. Further, electroless deposited NiP layers can be used for the integration of resistors. An electroless procedure will be described for metallizing alumina and fused quartz substrates, and further a method for producing resistive layers suitable for integrated resistors. After electroless plating the desired conductive patterns are obtained by localized electroplating with gold and etching away the unwanted parts of the NiP layer. Some properties of the conductive patterns obtained in this manner have been investigated, for instance: the adhesion between the metallic pattern and substrate, microwave losses in microstrip configuration, geometrical accuracies and performance of the resistive layers. A short description of the test methods applied will be given and the results discussed. Many hybrid integrated circuits for use at frequencies up to 22 GHz already have been made by using electroless procedures.

Shaft seal for high rotational speeds: J Peresse, Jour Phys, 26(3), March 1965, 121A–122A

Electroless methods for depositing conductive layers on insulating materials can be used in producing hybrid integrated circuits (HIC's), as alternatives to the evaporation and sputter deposition techniques. Compared with these techniques, electroless procedures are in general relatively simple and it is easy to metallize holes in substrates. Further, electroless deposited NiP layers can be used for the integration of resistors.An electroless procedure will be described for metallizing alumina and fused quartz substrates, and further a method for producing resistive layers suitable for integrated resistors. After electroless plating the desired conductive patterns are obtained by localized electroplating with gold and etching away the unwanted parts of the NiP layer.Some properties of the conductive patterns obtained in this manner have been investigated, for instance: the adhesion between the metallic pattern and substrate, microwave losses in microstrip configuration, geometrical accuracies and performance of the resistive layers. A short description of the test methods applied will be given and the results discussed.Many hybrid integrated circuits for use at frequencies up to 22 GHz already have been made by using electroless procedures.

Vacuum chamber for the IP-4M test equipment: V A KonomenkoInd Lab, 30(10), published March 1965, 1562–1563. Translated from the Russian Zav Lab, 30(10), Oct 1964, 1263–1264.

Electroless methods for depositing conductive layers on insulating materials can be used in producing hybrid integrated circuits (HIC's), as alternatives to the evaporation and sputter deposition techniques. Compared with these techniques, electroless procedures are in general relatively simple and it is easy to metallize holes in substrates. Further, electroless deposited NiP layers can be used for the integration of resistors.An electroless procedure will be described for metallizing alumina and fused quartz substrates, and further a method for producing resistive layers suitable for integrated resistors. After electroless plating the desired conductive patterns are obtained by localized electroplating with gold and etching away the unwanted parts of the NiP layer.Some properties of the conductive patterns obtained in this manner have been investigated, for instance: the adhesion between the metallic pattern and substrate, microwave losses in microstrip configuration, geometrical accuracies and performance of the resistive layers. A short description of the test methods applied will be given and the results discussed.Many hybrid integrated circuits for use at frequencies up to 22 GHz already have been made by using electroless procedures.