US20010008157A1 - Article comprising improved noble metal-based alloys and method for making the same - Google Patents

Article comprising improved noble metal-based alloys and method for making the same Download PDF

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US20010008157A1
US20010008157A1 US09/731,135 US73113500A US2001008157A1 US 20010008157 A1 US20010008157 A1 US 20010008157A1 US 73113500 A US73113500 A US 73113500A US 2001008157 A1 US2001008157 A1 US 2001008157A1
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article
alloy
noble metal
metal elements
elements
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David Bishop
Sungho Jin
Jungsang Kim
Ainissa Ramirez
Robert Van Dover
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/02—Contacts characterised by the material thereof
    • H01H1/021—Composite material
    • H01H1/023—Composite material having a noble metal as the basic material
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C5/00—Alloys based on noble metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/0036—Switches making use of microelectromechanical systems [MEMS]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/02—Contacts characterised by the material thereof
    • H01H1/021—Composite material
    • H01H1/027—Composite material containing carbon particles or fibres
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2300/00—Orthogonal indexing scheme relating to electric switches, relays, selectors or emergency protective devices covered by H01H
    • H01H2300/036—Application nanoparticles, e.g. nanotubes, integrated in switch components, e.g. contacts, the switch itself being clearly of a different scale, e.g. greater than nanoscale

Definitions

  • the invention relates to devices comprising electrical contact materials, in particular, high-speed switching relays, including relays based on microelectromechanical systems (MEMS).
  • MEMS microelectromechanical systems
  • High-speed switching relays are useful in a variety of applications in automatic test equipment, automotive technologies, and telecommunications technologies—e.g., signal routers, impedance matching networks, and tunable filters.
  • MEMS microelectromechanical systems
  • devices and components are fabricated from silicon using well-developed techniques related to integrated circuit processing.
  • Microelectromechanical relays are receiving increased attention because of their advantages over conventional relays—i.e., smaller size and less power consumption.
  • their potential is being realized in the integration of these systems with electronics, where large numbers of relays can exist on a single chip that may contain other electronics as well.
  • MEMS microrelays over semiconductor switches include lower on-resistance, higher off-resistance, higher dielectric strength, lower power consumption, and lower cost.
  • conventional switches using transistors have relatively low breakdown voltage (e.g., 30 V) and relatively low off-resistance (50 kilo-Ohms at 100 MHz), as discussed in U.S. Pat. No. 5,578,976.
  • Solid state switches tend to exhibit large on-state loss and poor off-state isolation.
  • microrelays have the potential to replace traditional solid state devices in significant markets.
  • complex switching arrays and devices designed to accommodate high-frequency signals with low loss are a natural extension for such MEMS relays.
  • Switches for telecommunications applications require a large dynamic range between on-state and off-state impedance, in the RF regime. Achieving a large on/off impedance ratio requires good electrical contact with minimal resistance when the switch is on (closed circuit) and low parasitic capacitive coupling when the switch is off (open circuit). Mechanical switches with metal-to-metal contact are still preferred where low insertion loss and high off-isolation are required, particularly in cost-sensitive applications. A key to the success of these relays is reliable, wear-resistant contact materials.
  • the invention provides a device having electrical contacts formed from an alloy having improved wear resistance.
  • the contact alloy is particularly useful in microrelay devices formed by MEMS technology.
  • the alloy contains at least one noble metal, such as rhodium, platinum, palladium, gold, or ruthenium.
  • noble metals includes Au, Ag, Pt, Pd, Ir, Rh, Ru, Os.
  • Noble metals are known to be useful as contact materials due to high oxidation- and corrosion-resistance and reasonable electrical conductivity. But because the contact materials in microrelay devices typically undergo billions of cycles of contact involving friction and wear, the contact materials must meet extremely high standards for wear resistance. By selecting particular alloying elements, along with providing a particular microstructure, it is possible to attain such higher wear resistance and still maintain a suitable electrical conductivity.
  • the alloys are chosen to allow sufficient precipitation hardening to improve wear resistance, but keep precipitation below a level that would unacceptably reduce electrical conductivity. This is achieved by using alloying materials that have very limited or no solid solubility in the noble metal matrix, e.g., less than 4 wt. % solid solubility.
  • the low solubility reduces the extent to which the conductivity will be compromised by conventional alloying effects, i.e., deterioration of the electrical conductivity due to solute atoms.
  • the low solubility also reduces the extent to which the second phase (precipitates) are able to coarsen (gow) during heat treatment, repeated contact operations, and similar processes. Yet, it is still possible to form sufficient precipitates in the noble metal matrix to achieve the desired mechanical strengthening and wear resistance.
  • the resulting alloy exhibits a mechanical hardness at least 30% higher than the noble metal matrix alone.
  • an alloy contains a noble metal matrix and insoluble, dispersoid particles, which offer a similar strengthening mechanism—e.g., mechanical hardness at least 30% higher than the noble metal matrix alone.
  • insoluble indicates a material having less than 0.01 wt. % solubility in the noble metal matrix.
  • dispersoid particles include oxides, nitrides, and carbides. Because the dispersoids have essentially no solubility in the matrix, the particles remain in the matrix to impede the motion of dislocations and grain boundaries, thereby strengthening the material.
  • FIG. 1 illustrates an embodiment of a microelectromechanical (MEMS) based microrelay.
  • MEMS microelectromechanical
  • FIG. 2A illustrates a two component temperature-composition phase diagram, reflecting limited solid solubility of the alloying element.
  • FIG. 2B illustrates a two component temperature-composition phase diagram with essentially no solid solubility of the alloying element, reflecting the creation of an intermetallic phase upon annealing, according to a first embodiment of the invention.
  • FIG. 3A schematically illustrates the microstructure of a supersaturated noble-metal based alloy of one embodiment of the invention, in an as-deposited state.
  • FIG. 3B schematically illustrates the microstructure of a noble-metal based alloy of one embodiment of the invention, after precipitation heat treatment.
  • FIG. 4 schematically illustrates the microstructure of a dispersoid containing alloy according to a second embodiment of the invention.
  • FIG. 5 illustrates a process useful for forming an alloy according to the second embodiment of the invention.
  • FIG. 6 illustrates another process useful for forming an alloy according to the second embodiment of the invention.
  • FIG. 7 illustrates a further process useful for forming an alloy according to the second embodiment of the invention.
  • Microelectromechanical relays offer the advantage of being smaller and consuming less power than conventional larger-scale relays. These relays perform an electrical function of connecting electrical paths for current to traverse, by actuation and bending of a cantilever-type switching arm such that circuit connection occurs at contacts made of specialized contact materials. Repeated contact at these contact points and the continual emission of current demand careful selection and fabrication of contact materials.
  • the invention involves use of particular contact materials containing alloyed noble metals, the alloying and associated microstructure allowing attainment of greater mechanical strength with a lower loss of conductivity as compared to conventional alloying.
  • FIG. 1 schematically illustrates a microelectromechanical microrelay device 10 of the invention.
  • an electrostatic voltage is applied between the beam electrode 12 and the actuator electrode 14 , which induces an attractive force and closes the gap between the cantilever 16 and the substrate 18 .
  • This movement of the cantilever 16 connects the electrical circuit by bringing the two contact pads 20 together.
  • the low-resistivity contact pads 20 formed from particular wear-resistant alloys of the invention, provide relatively low power loss and time-dependant degradation.
  • the switch is fabricated on a silicon substrate using conventional microfabrication techniques such as masking, etching, lift-off and deposition. (See, e.g., M. J.
  • the switch components are formed by thin-film deposition buildup or by etching away surrounding material.
  • the actuating part is composed of a cantilever arm 16 , typically formed from semiconducting or insulating material, such as silicon, silicon dioxide or silicon nitride, for example.
  • the contact pads 20 are deposited on part of the substrate as well as on part of the mating cantilever. According to the invention, one or both of the pads 20 are formed using a thin film of the noble-metal alloy, as described in more detail below.
  • Noble metals such as rhodium, platinum, palladium, gold, ruthenium, and silver, are useful as contact materials because these elements offer high oxidation- and corrosion-resistance and reasonable electrical conductivity. For instance, these materials have been used successfully in the reed switch industry. However, according to the invention, improved contact materials are obtained by alloying and processing such noble metals in a particular manner. Rhodium, for example, exhibits relatively good wear resistance, reasonable electrical conduction properties, relatively high mechanical strength and a high melting temperature (1966°C.). While these properties all indicate the usefulness of rhodium for contact materials, the contact materials in microrelay devices typically undergo billions of cycles of contact involving friction and wear. Increased wear-resistance is therefore desired.
  • the invention addresses this need by alloying and precipitation hardening of such noble metals.
  • the resulting alloys exhibit high mechanical strength due to the precipitation hardening, yet with relatively low conductivity loss due to solid-solution-induced effects.
  • creation of a solid-solution tends to reduce conductivity of the matrix material.
  • the alloying materials for use with noble metals have very limited or no solid solubility in the noble metal matrix. The advantages of selecting alloys with very low solubility limits are two-fold.
  • the low solubility reduces the extent to which the conductivity will be compromised by conventional alloying effects, i.e., substantial deterioration of the electrical conductivity of elemental metals due to addition of solute atoms.
  • the low solubility reduces the extent to which the second phase (precipitates) are able to coarsen during heat treatment, repeated contact operations, local heating, exposure to ambient temperature rise, and similar environmental changes. Such coarsening is undesirable because of potential deterioration of mechanical hardness and wear resistance.
  • FIGS. 2A and 2B illustrate phase diagrams for alloys that provide the desired properties.
  • FIG. 2A which reflects, for example, the rhodium-silicon system
  • FIG. 2B which reflects, for example, the rhodium-aluminum, or rhodium-boron system
  • FIG. 2B which reflects, for example, the rhodium-aluminum, or rhodium-boron system
  • the phase diagrams there exist higher temperature regions where it is possible to decompose a metastable solid solution and therefore form a second phase with moderate heating schemes. Within these temperature regions, the features of the alloys can be easily tailored.
  • the desired solid solubility of alloying elements in the noble metal matrix is less than 4 weight percent, advantageously less than 2 weight percent and more advantageously less that 0.5 weight percent, at or near room temperature (about 25°C.).
  • Typical compositions of the noble metal-based contact alloys contain 0.1-30 weight percent of the alloying element, advantageously 0.5-10 weight percent, and more advantageously 1-5 weight percent, with the particular amount varying depending on, among other things, the particular solubility and the desired degree of alloy strengthening. Control samples are easily prepared to allow one to tailor the properties to a particular application.
  • Rhodium-based alloy systems suitable for the wear-resistant contact materials of the invention include Rh—C, Rh—Ce, Rh—Dy, Rh—Y, Rh—Si, Rh—Zr, Rhodium-based alloy systems in which the alloying elements have essentially no solubility in rhodium include Rh—Al, Rh—B, Rh—Bi, Rh—Er, Rh—Gd, Rh—Ge, Rh—Pb, Rh—Sm, and Rh—Yb.
  • the precipitates formed are typically intermetallic compounds according to the phase diagrams.
  • Alloying systems to be avoided include R—Co, R—Cr, R—Ir, R—Cu, R—Fe, R—Hf, R—Mn, R—Mo, R—Nb, R—Ni, R—Os, R—Pd, R—Ru, R—Sb, R—Sn, R—Ta, R—Ti, R—V, R—W, as these alloying elements have substantial residual solubility in rhodium even after precipitation, and thereby deteriorate the electrical conductivity of the rhodium.
  • suitable alloying systems with limited solubility include Au—C, Au—Co, Au—Ho, Au—Lu, Au—Th, Au—Mn, Au—Re, Au—Rh, Au—Ru, Au—Sb, Au—Yb, Au—Y.
  • Systems with essentially no solubility include Au—B, Au—Bi, Au—Dy, Au—Er, Au—La, Au—P, Au—Pb, Au—Si, Au—Sr, Au—W.
  • Alloy systems to be avoided include Au—Ag, Au—Al, Au—Fe, Au—In, Au—Li, Au—Mg, Au—Nb, Au—Ni, Au—Pd, Au—Pt, Au—Sn, Au—Ta, Au—Ti, Au—V, Au—Zn, Au—Zr.
  • suitable alloys with limited or no solubility include Pt—B, Pt—Bi, Pt—Er, Pt—Pb, Pt—La, Pt—Mo, Pt—Ti (B and Ti having limited solubility and the others having essentially no solubility).
  • Systems to be avoided include Pt—Al, Pt—Nb, Pt—Ni, Pt—Os, Pt—Mn, Pt—Mo, Pt—V.
  • suitable alloys include Pd—B, Pd—Bi, Pd—Si (B having limited solubility and the others having essentially no solubility).
  • Systems to be avoided include Pd—Fe, Pd—Al, Pd—C, Pd—Hf, Pd—Mn, Pd—Ir, Pd—Y, Pd—Dy, Pd—Ho, Pd—Ta, Pd—Mo, Pd—Nb, Pd—Ni, Pd—Pb.
  • suitable alloys include Ru—C, Ru—Ce, Ru—Hf, Ru—Lu, Ru—La, Ru—Si, Ru—Bi, Ru—Gd (C, Ce, and Hf having limited solubility, and the others having essentially no solubility).
  • Systems to be avoided include Ru—Co, Ru—Cr, Ru—Mo, Ru—Ti, Ru—Fe, Ru—Ir, Ru—Nb, Ru—Ni, Ru—Os, Ru—Re.
  • the presence of precipitates provides a strengthening mechanism—the precipitates impede the movement of dislocations and grain boundaries, and the alloys are therefore harder than the elemental noble metal itself or solid-solutioned noble metal alloys.
  • the contribution of the precipitates to improving the mechanical strength of the films also improves the wear resistance of the films.
  • An additional advantage of using such a forced-in alloy system is that the noble metal matrix becomes depleted with the alloying element as alloy decomposition occurs.
  • the electrical conductivity of the alloy improves after such precipitation, to a relatively high value that is often comparable to the conductivity of the noble metal itself.
  • the techniques for providing alloy strengthening and improved wear resistance according to the invention are able to provide a relatively low loss of electrical conductivity, contrary to conventional alloying practices.
  • the electrical conductivity of the alloy of this embodiment is typically at least 15% of the conductivity of the pure element noble metal, advantageously at least 30% of the conductivity of the pure element, more advantageously at least 50% of the conductivity of the pure element.
  • the mechanical hardness of the alloy should be at least 30% greater than the hardness of the pure element, advantageously at least 50% greater than the hardness of the pure element, more advantageously at least 100% greater than the hardness of the pure element.
  • the hardness of the alloy should be at least 15% greater than the hardness of the same alloy but in single phase form, advantageously 30% greater, and more advantageously at least 60% greater.
  • the microstructure of the alloys of this first embodiment contain a fine distribution of precipitate particles, the particles typically less than 500 nm in average diameter, advantageously less than 150 nm, more advantageously less than 50 nm.
  • the precipitate particles are typically present in a volume fraction of 0.1% to 30%, advantageously 0.5% to 5%. (Greater than 30% tends to deteriorate the conductivity and cause embrittlement.)
  • This microstructure is generally obtained by one of two processing techniques.
  • the first is to create such a structure in situ by film deposition (e.g., sputtering) with the substrate temperature sufficiently high (typically greater than 100° C., advantageously greater than 200° C.) to drive the segregation of the second phase precipitate during the deposition. In this case, no post-deposition annealing process is needed.
  • the second approach is to prepare the thin film with the supersaturated alloying element as a solid solution in the noble metal matrix, and then, after deposition of the film, perform a post-deposition heat treatment to decompose the alloy and create the desired precipitates.
  • the alloy Upon heating, the alloy will be in a two-phase region and precipitates will form. Continuous heating and cooling, or isothermal holding at a constant temperature, are both possible.
  • Typical decomposition temperatures are 100-800° C., advantageously 100-400° C.
  • Typical decomposition time is 0.01-100 hours, advantageously 0.1-20 hours.
  • FIGS. 3A and 3B A schematic illustration of the microstructures of the metal before and after decomposition heat treatment is illustrated in FIGS. 3A and 3B. In FIG.
  • the as-deposited (but not heat treated) microstructure 30 contains forced-in solute atoms, but no precipitates.
  • the post-heat treatment microstructure 40 contains the desired precipitates 42 .
  • the heat treatment generally improves the electrical conductivity, compared to the as-deposited alloy, by at least 30%, due to movement of solute atoms from the matrix to the precipitates.
  • the alloys of this embodiment are formed into thin films appropriate for contacts by any suitable technique, including sputtering, thermal evaporation, electron-beam evaporation, laser ablation, glow discharge, ion plating, ion-beam assisted deposition, ion-cluster beam techniques, chemical vapor deposition, electrolytic deposition, and electroless plating.
  • the improved contact alloy is a composite structure containing a noble metal or alloy matrix and insoluble, non-coarsening dispersoid particles.
  • the composite structure provides high mechanical strength with substantially no solid-solution-induced loss of electrical conductivity.
  • FIG. 4 illustrates a typical microstructure for inventive composite-structured contact metal with desirable microstructural characteristics.
  • the matrix 50 is a noble elemental metal or alloy within which nano-scale, insoluble dispersoids particles 52 are distributed.
  • the dispersoid particles impede the motion of dislocations or grain boundaries, thus increasing the contact metal strength and wear resistance.
  • the insolubility reduces the possibility that the conductivity will be compromised, in contrast to conventional alloying in which the electrical conductivity generally deteriorates due to solute atom additions.
  • the insolubility also reduces the extent to which the second phase (dispersoid particles) can coarsen (grow) during heat treatment, repeated contact operations, local heating, exposure to ambient temperature rise, and similar actions, which is desirable since such coarsening typically causes a deterioration in strength and wear resistance.
  • the noble metal matrix prefferably be a pure element, an alloy of several noble metal elements, or multilayer thin film structure of such elements.
  • Dispersoid particles include oxides, nitrides, carbides, sulfides, and fluorides, as well as other insoluble stable compounds such as oxynitrides or oxycarbides.
  • Such materials are capable of being produced by reaction of various elements with reactive gases, e.g., oxygen, air, or water in the case of oxides; nitrogen or ammonia in the case of nitrides; methane, acetylene, or propane in the case of carbides; H 2 S in the case of sulfides; and HF or CF 4 in the case of fluorides.
  • Particular dispersoid materials include Al 2 O 3 , SiO 2 , TiO 2 , ZrO 2 , HfO 2 , MgO, Y 2 O 3 , In 2 O 3 , SnO 2 , GeO 2 , Ta 2 O 5 , AIN, BN, Si 3 N 4 , TiN, ZrN, TaN, WC, SiC, TaC, TiC, ZrC, CdS, CuS, ZnS, and MgF 2 , CaF 2 , CeF 3 , ThF 4 .
  • Oxycarbides and oxynitrides of Ti, Ta, Al, and Si, along with arsenides, amorphous phases, intermetallics, fullerenes, and nanowires (e.g., carbon nanotubes) are also capable of acting as dispersoid material.
  • the dispersoid particles typically range in size from 1 to 5000 nm, advantageously 2 to 500 nm, more advantageously 2 to 50 nm.
  • the dispersoid particles are typically present in the alloy in an amount ranging from 0.1 to 30 volume percent, advantageously 0.5 to 5 volume percent. Too high a volume fraction, for example in excess of 30%, tends to deteriorate the electrical conductivity of the noble metal, and also tend to lead to undesirable embrittlement of the contact material.
  • the alloys of this second embodiment are able to be fabricated into a thin film configuration by any suitable technique, e.g. sputtering, thermal evaporation, electron-beam evaporation, laser ablation, glow discharges, ion plating, ion-beam assisted deposition, ion-cluster beam techniques, chemical vapor deposition, electrolytic deposition or electroless plating with simultaneous trapping during deposition of dispersoid particles mixed in the liquid.
  • any suitable technique e.g. sputtering, thermal evaporation, electron-beam evaporation, laser ablation, glow discharges, ion plating, ion-beam assisted deposition, ion-cluster beam techniques, chemical vapor deposition, electrolytic deposition or electroless plating with simultaneous trapping during deposition of dispersoid particles mixed in the liquid.
  • a particularly useful process for preparing the alloy of this second embodiment is co-deposition or co-sputtering from two separate targets—one containing the noble metal matrix material and the other containing the dispersoid material, as illustrated in FIG. 5.
  • the Figure shows sputtering, e.g., dc-magnetron sputtering, of a noble metal target 60 and sputtering, e.g., rf-sputtering, of an oxide target 62 being simultaneously performed to obtain a composite structure having dispersoid particles 66 within a noble metal matrix 68 . It is possible for the co-deposition to be carried out on a heated substrate 64 , e.g.
  • Such post-deposition heat treatment is advantageously carried out either in an inert atmosphere (such are argon, helium or nitrogen), in a reducing atmosphere (such as H 2 , H 2 +N 2 , CO), or in a vacuum, to reduce or avoid oxidation of the contact metal film surface.
  • an inert atmosphere such are argon, helium or nitrogen
  • a reducing atmosphere such as H 2 , H 2 +N 2 , CO
  • a vacuum to reduce or avoid oxidation of the contact metal film surface.
  • Another technique for forming the alloy of this second embodiment is an in-situ reactive deposition technique, such as reactive sputtering or evaporation in an oxygen-containing atmosphere, as reflected in FIG. 6.
  • the sputtering target 70 contains both the noble metal 72 and the reactive dispersoid-forming metal 74 , for example, an Rh-Al alloy target or a target having separate areas of Rh and Al.
  • the Al atoms react with oxygen atoms in the atmosphere and form Al 2 O 3 particles 76 , which are trapped and incorporated in the unreactive Rh metal film 78 deposited on the substrate 80 .
  • a variety of dispersoid-forming metals are possible, including Al, Ti, Si, Mg, Zr, W, Ta, and Y. These elements are capable of reacting with oxygen, nitrogen or fluorine atoms in a deposition chamber to form the corresponding oxide, nitride or fluoride. It is also possible to vary this technique to deposit films in a oxidizing plasma, i.e., use an rf-excited discharge and an oxygen pressure of less than one Torr to generate oxide particles within the matrix material.
  • Another technique suitable for preparing the composite alloy of this second embodiment is an internal oxidation process.
  • a pure noble metal or noble metal alloy film 90 containing one or more strongly oxidizing elements such as Al, Ti, Si, Zr, or rare earth elements is deposited onto a substrate 92 , with atoms of these oxidizing elements metastably incorporated in the noble metal matrix.
  • the film 90 is then subjected to a heat treatment in a chamber 94 filled with an oxidizing atmosphere such as O 2 , O 3 or Ar+O 2 , such that sufficient oxygen atoms diffuse into the deposited film 90 to react with the oxidizable element atoms and form oxide dispersoid particles 96 .
  • the alloys of this second embodiment exhibit a relatively low loss of electrical conductivity, versus the matrix metal alone, while offering improved wear resistance.
  • the conductivity of the alloy is typically at least 50% of the conductivity of the noble metal matrix alone, advantageously at least 80%, more advantageously at least 90%.
  • the mechanical hardness of the alloy is typically at least 30% greater than that of the noble metal matrix alone, advantageously at least 50% greater, more advantageously at least 100% greater.
  • the alloys of the invention when used as contact materials, e.g., in MEMS relays, are typically formed as a film having a thickness of 1 to 10,000 nm, advantageously 1 to 1000 nm.
  • noble metals because of their inert nature, tend to exhibit poor adhesion to substrates, particularly when deposited as a thin film, and often delaminate.
  • adhesion-promoting layers include chromium, titanium, tantalum, zirconium and alloys containing such metals.
  • adhesion-promoting layer To provide smooth transition from the adhesion-promoting layer to the contact alloy, it is possible to add a small amount of these adhesion promoting elements to the alloy, e.g., 0.1 to 5 weight percent, advantageously 0.1 to 1 weight percent.
  • the typical thickness of the adhesion-promoting layer is 1 to 1000 nm, advantageously 1 to 100 nm.
  • alloying systems that do not require such adhesion-promoting measures. It is possible to attain both self-adherence and wear resistance by selection of alloying elements.
  • Useful matrix-alloying element combinations for providing these properties include Rh—Si, Rh—Al, R—Zr, R—Y, R—Sm, A—Si, A—Dy, A—La, P—Ti, P—La, P—Si, R—Hf, R—Si, and R—La. It is notable that several of these alloying elements are suitable for forming precipitates according to the first embodiment of the invention, or insoluble dispersoids according to the second embodiment, depending on the formation process. Alloys containing Si are particularly useful for MEMS relay contacts, as the substrate surface in MEMS devices typically are silicon dioxide (SiO 2 ) or silicon (Si), onto which contact alloys containing silicon bond well.

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US20040238797A1 (en) * 2003-06-02 2004-12-02 Aisan Kogyo Kabushiki Kaisha Powder compositions and methods and apparatus for producing such powder compositions
US7057246B2 (en) 2000-08-23 2006-06-06 Reflectivity, Inc Transition metal dielectric alloy materials for MEMS
US7071520B2 (en) 2000-08-23 2006-07-04 Reflectivity, Inc MEMS with flexible portions made of novel materials
US20060275539A1 (en) * 2005-05-23 2006-12-07 Seiko Epson Corporation Transparent conductive film and method forming thereof, electrooptic device and electronic apparatus
US20070135552A1 (en) * 2005-12-09 2007-06-14 General Atomics Gas barrier
US20070189916A1 (en) * 2002-07-23 2007-08-16 Heraeus Incorporated Sputtering targets and methods for fabricating sputtering targets having multiple materials
US20080044685A1 (en) * 2003-12-31 2008-02-21 Sungho Jin Articles Comprising High-Electrical-Conductivity Nanocomposite Material and Method for Fabricating Same
CN100412607C (zh) * 2003-09-29 2008-08-20 松下电器产业株式会社 微型电力机械系统及其制造方法
US20080294372A1 (en) * 2007-01-26 2008-11-27 Herbert Dennis Hunt Projection facility within an analytic platform
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