Abstract: Novel composite metal membranes are disclosed that contain an intermetallic diffusion barrier separating a hydrogen-permeable base metal and a hydrogen-permeable coating metal.

Abstract: Electrical measurements on shallow Si n/sup +/-p junction diodes with a 30-nm TiSi/sub 2/ contacting layer demonstrate that an 80-nm-thick amorphous Ta/sub 36/Si/sub 14/N/sub 50/ film prepared by reactive RF sputtering of a Ta/sub 5/Si/sub 3/ target in an Ar N/sub 2/ plasma very effectively prevents the interaction between the Si substrate with the TiSi/sub 2/ contacting layer and a 500-nm Cu overlayer. The Ta/sub 36/Si/sub 14/N/sub 50/ diffusion barrier maintains the integrity of the I-V characteristics up to 900 C for 30-min annealing in vacuum. It is concluded that the amorphous Ta/sub 36/Si/sub 14/N/sub 50/ alloy is not only a material with a very low reactivity for copper, titanium, and silicon, but must have a small diffusivity for copper as well. >

Abstract: The ability of thin reoxidized nitrided oxide (ONO) gate dielectrics formed by rapid thermal processing to act as a barrier to boron penetration resulting from p/sup +/ poly gate processing are investigated. Measurements comparing the threshold voltage instability of capacitors fabricated with BF/sub 2/ implanted poly gates subjected to various postgate thermal cycles have been performed. The ONO gate dielectrics are found to be an excellent impurity barrier to boron diffusion, even in the presence of fluorine. The extent of the nitridation is also found to affect the diffusion barrier properties, with the highest temperature nitridations forming the best barriers. Reoxidation of the nitrided films reduces the barrier properties somewhat, but improvement is still observed over SiO/sub 2/. >

Abstract: Initial results are presented and discussed in relation to a research program focused on investigating the feasibility of using ion beam sputter deposition to produce layered films for metallization of microcircuits. An automated ion beam sputter‐deposition system has been used to produce W/Cu/W layered films and investigate their microstructural, morphological, and electrical characteristics. Layered films with smooth surfaces have been deposited on planar surfaces and in vias with reasonable conformality. It is demonstrated that the W layer microstructure can be tailored by controlling the deposition parameters. The control of the W layer microstructure can serve to improve its diffusion barrier properties with respect to similar films produced by other techniques. Initial measurements of the resistivity of the layered film structure yielded values close to that characteristic of bulk copper, a desirable parameter for application in microcircuit metallization.

Abstract: A diffusion barrier which reduces the diffusion of a copper feature into an oxygen containing polymer is provided by a copper metal alloy. The diffusion barrier is fabricated by coating a metal on a copper feature, heating the metal and copper feature to form an alloy of the copper feature and the metal, etching the non-alloyed metal which covers the alloy, and depositing an oxygen containing polymer on the alloy. Preferably the metal is aluminum and a copper aluminum alloy diffusion barrier is at least 300 angstroms thick and contains at least 8 percent aluminum on the surface in contact with the polymer.

Abstract: A method of inhibiting dopant diffusion in silicon using germanium is provided. Germanium is distributed in substitutional sites in a silicon lattice to form two regions of germanium interposed between a region where dopant is to be introduced and a region from which dopant is to be excluded, the two germanium regions acting as a dopant diffusion barrier.

Abstract: The invention provides a method for electrically connecting a polysilicon-filled trench to a diffusion region in a semiconductor device, wherein the trench and diffusion region are separated by a dielectric. The method provides for formation of a strap or bridge contact by utilizing a diffusion barrier layer which prevents diffusion into an overlying polysilicon layer when a subsequent boron out-diffusion step is performed. Selective etching is then utilized to remove the polysilicon layer where no boron has diffused, leaving a polysilicon strap connecting the trench and diffusion region.

Abstract: This paper reports on reactively sputtered Ta-Si-N films that are investigated as diffusion barriers between silicon and Au layers. Analyses by backscattering spectrometry and electrical measurements on shallow n{sup +}p junction diodes reveal that an amorphous Ta{sub 36}Si{sub 14}N{sub 50} thin film approximately 100 nm thick very effectively preserves the integrity of the metallization on shallow junctions up to 30 min annealing at 750{degrees} C in vacuum. (The Au-Si eutectic is at 360{degrees} C). At that temperature small openings appear in the Au overlayer which do not, however, affect the electrical characteristics of the diodes. Destructive metallurgical interactions occur at higher temperatures causing a shorting of the shallow junction diodes.

Abstract: There has been provided an electrical component having resistance to oxidation and wear. The component has a copper or copper alloy substrate coated with a relatively thick layer of silver. A thin layer of gold may be deposited on the external surface of the silver coating layer to improve oxidation resistance, lubricity and to serve as a diffusion barrier.

Abstract: This paper reviews recent studies of the low-temperature chemical vapor deposition of titanium nitride thin films suitable for ULSI applications. In addition to the comprehensive studies available for films grown thermally from TiCl4 and NH3, films deposited from organometallic precursors are discussed, as well as those derived from plasma-enhanced techniques. Two applications of such films for ULSI are as a diffusion barrier between different conductors, and as a nucleation layer for CVD tungsten. Properties of LPCVD TiN for these applications, are covered including film conformality, effectiveness as a diffusion barrier, contact resistance, nucleation of tungsten, and the influence of any residual chlorine.

Abstract: The performance of pulsed laser deposited tungsten carbide films as diffusion barriers between a 〈100〉 Si substrate and an Al overlayer has been investigated. Four‐point probe measurement of resistance is employed to monitor the electrical stability of the Al/WC/Si metallization schemes upon thermal annealing in a vacuum for 30 min in a temperature range from 100 to 500 °C. The Glancing angle x‐ray diffraction technique has been used to characterize the as‐deposited as well as annealed samples. To study the metallurgical interaction between Al overlayer and the barrier film, experiments on isothermal annealings are carried out. The data obtained have been used to estimate the activation energy for the formation of the intermetallic compound WAl12. Morphological features of the annealed samples have been obtained by employing the technique of scanning electron microscopy.

Abstract: A multi-layer gate electrode is provided to prevent dopant depletion of a polysilicon in the manufacture of the electrode containing doped polysilicon and metal silicide. First, a multi-layer structure is produced containing a doped polysilicon structure, a diffusion barrier structure and a silicon structure. After deposition of a metal layer covering the multi-layer structure, a metal silicide structure is produced from the silicon structure and the metal layer in a tempering process. The diffusion barrier structure thereby prevents diffusion of dopant out of the polysilicon structure into the metal silicide structure. This may be used in a salicide process.

Abstract: A load resistor for use in a semiconductor integrated circuit consists of two portions of conductive material, typically strips of either a silicide or a composite polycrystalline silicon layer and silicide layer formed thereon, formed on a semiconductor substrate and separated from each other by a selected distance. An electrically conductive dopant diffusion barrier is formed on the first and second portions of conductive material. A polycrystalline silicon material is then placed on the structure such that one portion of the polycrystalline silicon material is in ohmic contact through the diffusion barrier with the first portion of conductive material and the other portion of the polycrystalline silicon material is in ohmic contact through the diffusion barrier with the second portion of conductive material. Typically the polycrystalline silicon material is placed on an insulation layer formed on the semiconductor substrate in the portion of the substrate between the two portions of conductive material. The diffusion barrier prevents any dopant from the conductive material from diffusing into the polycrystalline silicon material thereby allowing the polycrystalline silicon material to function as a load resistor having a high resistance in the giga-ohms range. Subsequent high temperature processing of the structure does not change the resistance of the polycrystalline silicon because the dopant diffusion barrier prevents any dopant from the underlying conductive material from diffusing into the polycrystalline silicon material.

Abstract: An integrated circuit such as a MOS transistor, having an electrically conductive diffusion barrier at the metal/silicon interface and a method of manufacture therefor is disclosed. The metal/silicon interface is formed by selective metal deposition onto silicon. According to the method, the interface is subjected to a nitrogen-based plasma during a period of at least five minutes. The interface is brought to a temperature greater than 500° C. during this period, in order to create a diffusion barrier comprising a silicon nitride layer. The interface is then subjected to an annealing treatment under a neutral atmosphere so as to remove the nitrogen previously introduced into the metal. The diffusion barrier forms a linking and protecting interface between each source drain or gate zone of the MOS transistor and the corresponding layer of metal covering the latter.

Abstract: Single‐chamber in situ laser processing of high‐Tc YBa2Cu3O7−δ film on stainless steel (302) substrates with yttria‐stabilized zirconia (YSZ) buffer layers, has been carried out using a multitarget deposition system. YSZ and YBa2Cu3O7−δ films were deposited sequentially by KrF excimer laser (λ=248 nm) at substrate temperature of 650 °C. The films were characterized by x‐ray diffraction, four point probe ac electrical resistivity, scanning electron microscopy and Auger electron spectroscopy (AES) techniques. Due to the matching of the thermal expansion coefficient of YSZ with stainless steel and its diffusion barrier characteristics, good quality high‐Tc films have been grown on stainless steel substrates with superconducting transition temperature, Tc (onset), of 92 K and Tco (zero resistivity temperature) of 84 K. AES depth profiling indicated little interdiffusion of Fe across the interface of YSZ and stainless steel. A laser evaporation method was used for patterning the YBa2Cu3O7−δ films and critical ...

Abstract: A load resistor for use in a semiconductor integrated circuit consists of two portions of conductive material, typically strips of either a silicide or a composite polycrystalline silicon layer and silicide layer formed thereon, formed on a semiconductor substrate and separated from each other by a selected distance. An electrically conductive dopant diffusion barrier is formed on the first and second portions of conductive material. A polycrystalline silicon material is then placed on the structure such that one portion of the polycrystalline silicon material is in ohmic contact through the diffusion barrier with the first portion of conductive material and the other portion of the polycrystalline silicon material is in ohmic contact through the diffusion barrier with the second portion of conductive material. Typically the polycrystalline silicon material is placed on an insulation layer formed on the semiconductor substrate in the portion of the substrate between the two portions of conductive material. The diffusion barrier prevents any dopant from the conductive material from diffusing into the polycrystalline silicon material thereby allowing the polycrystalline silicon material to function as a load resistor having a high resistance in the giga-ohms range. Subsequent high temperature processing of the structure does not change the resistance of the polycrystalline silicon because the dopant diffusion barrier prevents any dopant from the underlying conductive material from diffusing into the polycrystalline silicon material.

Abstract: An examination has been made of the chemical stability of SiC monofilaments, with and without sputtered coatings intended to produce diffusion barrier layers of Y2O3, in contact with matrices of Mg Li alloy (up to 400°C) and Ti (up to 1000°C). Even very thin layers were found to offer some protection in the Mg Li alloy, under conditions such that the uncoated fibres suffered catastrophic embrittlement by penetration of Li into the grain boundaries. Yttrium-coated fibres in a Ti matrix were found to exhibit only marginally improved stability when compared with uncoated fibres. The probable explanation for this has been identified as a tendency for Y to penetrate into the SiC fibre before a stable Y2O3 layer could form, although high hydrogen levels in the Ti matrix (absorbed during composite fabrication) may also have impaired the interfacial stability in much of the material examined. Fibre preoxidation prior to Y coating was found to inhibit this Y penetration into the fibre material, allowing a Y2O3 barrier layer to form in situ. This barrier layer has been shown to offer considerable fibre protection.

Abstract: In this paper a physical model is presented for boron penetration through an oxynitride gate dielectric prepared by rapid thermal processing in a nitrous oxide (N2O) ambient. Compared with a conventional rapid thermally grown oxide, oxynitride dielectrics show excellent diffusion barrier properties to the dopant (BF2). The Auger electron spectroscopy nitrogen depth profile shows nitrogen pileup at the Si/SiO2 interface, which may explain the lower segregation coefficient (≊20 times lower) of the oxynitride dielectric, as expected from suprem‐iii simulation with modified diffusivity values.

Abstract: A novel transparent electrode system has been developed for thin film electroluminescent displays in which the poor conductivity of the indium-tin-oxide (ITO) electrodes has been augmented by high-conductivity buses of thick a luminum or silver. The augmented electrode system consists of patterned ITO electrodes, 200 Fm wide, centered over narrow aluminum or silver lines 40 ~m wide and separated by an intermediate diffusion barrier film of t i tanium to promote adhesion to the ITO and prevent blackening of the main ITO electrode by interfacial reactions. The sheet resistances of the augmented ITO electrodes (A1-Ti-ITO and Ti-Ag-Ti-ITO) were lowered by two orders of magnitude relative to the unaugmented ITO electrodes, yielding absolute values on the order of 0.1 ~/s. Indium-tin-oxide (ITO) is the most widely used material for the transparent electrodes in alternating current-thin film electroluminescent (ACTFEL) displays (1-3). Speed and brightness uniformity depend critically on ITO line resistance, particularly for large-area displays. Even with integrated ITO lines, a 'zebra' pattern of brightness contrast occurs due to high line resistance. Therefore, to achieve higher conductivity of the transparent electrodes in ACTFEL panels, a structure was developed in which the low-conductivity ITO electrodes were augmented by buses of thick, narrow, high-conductivity metals. Not only would higher conductivity transparent electrodes reduce line delay in larger panels, but they would reduce the power consumption in these low current-high voltage devices and increase the brightness of existing displays by allowing them to be driven at much higher frequencies (4). Currently, ITO electrodes exhibiting >85% transmission in the visible spectrum and sheet resistances of 5-20 ~/[] are possible, with film thicknesses greater than 500 nm (5). However, when ITO film thicknesses in the range of 100150 nm are employed, the sheet resistance increases to levels of 30-90 ~/[~ (6). Since sheet resistances on the order of 1 ~/[~ are necessary for large-area displays, only very thick ITO lines will yield the desired properties. This is due in part to the dissipation caused by capacitive currents in highly resistive material. These thick lines lead to dielectric breakdown at the edges of the patterned ITO due to enhanced field effects and poor step edge coverage of the overlying films in the ACTFEL stack (7). A cross section of a typical pixel in an ACTFEL device, indicating where breakdown is likely to occur, is shown in Fig. i. To avoid premature breakdown at step edges, Ketchpel and Wu (7) employed a thick film aperture layer-bus rail structure for the rear aluminum electrode. A thick film insulator layer, aligned over the step edge, removed the parallel bus rail conductor in this structure from the high electrical field applied to the emitter. Our augmented electrode structure differs from this one in that a trenched metal bus rail was fabricated within the surface layers of the glass. The augmented electrode structure developed to achieve higher conductivities is shown in Fig. 2. Here, low conductivity ITO electrodes 200 ~m wide were centered over 40 ~tm wide metal bus lines. The electrode structures evaluated in this study included ITO, AI-ITO, AI-Ti-ITO, Ti-Ag-ITO, and Ti-Ag-Ti-ITO. To prevent interdiffusion of the aluminum/silver and ITO during subsequent heattreatment steps, and to promote adhesion of these metals * Electrochemical Society Active Member. 2070 to the glass and ITO, intermediate thin films of t i tanium were employed. Blackening of the transparent ITO lines has been observed during the deposition of dielectrics onto ITO (8). Here, the reduction of ITO occurs by displacement reactions with metals that form more stable oxides than indium oxide and tin oxide at the deposition temperature. Consequently, another role of the intermediate barrier film is to minimize the formation of insulating oxide films between the ITO and the bus metallization. These oxide films could lead to undesirable contact resistances and higher sheet resistances for the composite electrode structure. Ti tanium was first proposed as a contact material between A1 and Si in 1972 and was reported to have good diffusion barrier properties (9). However, this t i tanium metallurgy produced interfacial reactions with A1 which consumed the thin Ti layers at elevated temperatures and resulted in the formation of TiA13 intermetallics (10). It was reported in this study that annealing at 500~ consumed as much as 1500/~ of t i tanium in 30 min. In a more recent study of the electrical properties of this A1/Ti contact metallurgy (11), the contact resistance increased with increasing annealing temperatures, suggesting that the growth of this TiA13 intermetallic layer was a function of time at temperature. Therefore, if a thin layer of t i tanium is to be used as a diffusion barrier between the a luminum bus metal and ITO, it must be thick enough to survive any subsequent annealing steps. Historically, the system Ag-Ti and later Ag-Pd-Ti was used extensively as the metallurgy for high-intensity solar rear aluminum eleclrode 7 ~ dieleclric/~ and ~, phosphor x, ~

Abstract: An improved high performance x-ray tube rotating having a graphite anode therein and method of preparation thereof. A graphite anode body is provided with a microcracked contiguously disposed diffusion barrier layer of rhenium on the surface of the anode body. An anode target layer is then deposited on top of the barrier layer.

Abstract: The thermally induced reactions in Cu/Si, Cu/metal, Cu/silicide and Cu/dielectric films have been studied by both Rutherford backscattering and Auger electron spectroscopy. Diffusion barrier layers (TiN, TiW, Ta, Cr and Co) have been tested in the Cu based metallization regime. Alloying Cu with other elements (Pd, Ti, Cr and Al) can significantly prevent Cu from oxidation. Methods to produce Cu thin films (e.g. electroless Cu) have been summarized. >

Abstract: There is provided a molecular sieve coated with a non-oxide ceramic. The molecular sieve may be a zeolite, such as ZSM-5, and the ceramic coating may be, e.g., boron nitride. The coated molecular sieve may be prepared by contacting the molecular sieve with a ceramic precursor material comprising a thermally decomposable material, such as polyborazylene, and thermally decomposing this thermally decomposable material. The coated molecular sieves may be used as organic conversion catalysts. The non-oxide ceramic coating may alter or enhance the shape-selective properties of the molecular sieve by providing a diffusion barrier to molecules.

Abstract: Low-temperature (200°C), atmospheric pressure chemical vapor deposited (APCVD) titanium nitride films are shown to be effective diffusion barriers for the Au/TiN/Si contact scheme. The samples were analyzed by Rutherford backscattering spectroscopy (RBS), and by optical microscopy. It was found that a pure TiN layer constitutes an effective barrier for 40 min at 550°C, at which point the TiN cracks and peels. Even thin layers of TiN (200A thick) can significantly reduce the amount of interdiffusion between the gold and silicon.

Abstract: The efficiency of physical vapour deposition (PVD) coatings depends strongly on the adhesion to the substrate and on the wear resistance. Detailed information from the microscopic viewpoint on the interface characteristics is still lacking in most tribosystems. Therefore for two advanced tool materials (the powder metallurgically produced high speed steel ASP 30 and a TiC-based cermet) we studied the following parameters: the surface morphology and microstructure of the substrte and the TiN (PVD) coating; the distribution of the elements at the interface; possible reactions between elements from the substrate and the coating; the TiN coating as a diffusion barrier at the TiC-based cermet couple with Armco iron; and the possible interaction between titanium and iron atoms at the interface. For characterization, scanning and transmission electron microscopy with energy-dispersive X-ray analysis, Auger electron spectroscopy and electron probe microanalysis depth profile measurements, X-ray analyses, a surface profilometer, the diffusion couple technique and conversion electron Mossbauer spectroscopy was used.

Abstract: The reliability of copper multilevel interconnections requires good adhesion and the prevention of copper diffusion into the interlevel dielectric. Magnesium is a candidate for an adhesion layer and diffusion barrier for copper due to the high heats of formation of magnesium oxides, fluorides and sulfides and the formation of low resistivity compounds of Mg with copper. An investigation of the interactions in thin films of copper and magnesium has been carried out in the temperature range of 25°C to 500°C. The results of these reactions leading to phase formation in Cu/Mg bilayers deposited on Si3N4 or SiO2 using X-ray diffraction, in situ sheet resistance, and Rutherford backscattering measurements are presented in this paper. It was found that the Mg-rich phase CuMg2 is the first phase to form on annealing to approximately 215°C, followed by the formation of the Cu-rich phase Cu2Mg at about 380°C in the presence of excess Cu.

Abstract: An alumina (Al2O3) diffusion barrier coating to inhibit the interfacial reactions between boron-carbide-coated boron (B4C/B) fibers and a nickel-aluminide (Ni3Al) (IC-221) matrix was investigated. The alumina diffusion barrier was deposited on the B4C/B fibers using chemical vapor deposition. Also, Saphikon single-crystal Al2O3 fibers were used to demonstrate the compatibility between Al2O3 and Ni3Al. The detailed microstructures and chemical compositions of the fibers, coating, and matrix before and after various thermal exposures were analyzed using scanning electron microscopy, energy dispersive x-ray analysis, and ion microprobe mass analysis. The interfacial reaction products present after 6 h at 980 °C were characterized, and Ni was found to be the dominant diffusion species. The alumina diffusion barrier shows promise for effectively inhibiting the deleterious reactions between B4C/B fibers and the Ni3Al matrix. The uncoated B4C/B fibers were consumed by the matrix after fabrication alone, whereas the Al2O3 coated fibers demonstrated resistance to the matrix for 25 h at 880 °C and 6 h at 980 °C. The Saphikon fiber-reinforced Ni3Al composites demonstrated excellent compatibility after 50 h at 1000 °C. Zirconium (Zr)-rich precipitates on the order of 2 μm in diameter formed at the fiber interface after this exposure, but no gross reaction was indicated between the fiber and the matrix.

Abstract: The development of titanium-based composites has been hindered largely because of interfacial diffusion. When SiC is in contact with titanium at elevated temperatures, metal silicide (Ti5Si3) and carbide (TiC) are formed. The aim of our work is to reduce the fibre-matrix interaction at high temperatures by interposing compounds between the metal and SiC reinforcement. Procedures are described for the formation of thin layers on silicon carbide fibres (Sigma) by sputter deposition. Sputtering offers good control over density and stress state, thickness and composition. Past work has shown that sputtered Y2O3 deposited on SiC, SiCSi or metal can reduce the degree of ceramic-metal reaction. Use of the Gibbs free energy of formation of TiO2 provides a simple basis for the assessment of this material for use in a titanium matrix. Since TiSi2 and silicon are also present in the TiSi diagram, they could act as diffusion barriers. Coatings of TiSi2, Y2O3 and ZrO2 have been produced by sputter deposition. The stoichiometry of the coatings has been revealed by Rutherford backscattering spectrometry. Coated fibres have been used to prepare titanium-based composites by hot pressing. Annealing between 900 and 1100°C has been performed. Scanning microscopy, Auger electron spectroscopy and transmission electron microscopy have been used to investigate the interfacial products.