Abstract: An integrated circuit and method of fabricating the integrated circuit is disclosed. The integrated circuit includes vertical bipolar transistors (30, 50, 60), each having a buried collector region (26′). A carbon-bearing diffusion barrier (28 c) is disposed over the buried collector region (26′), to inhibit the diffusion of dopant from the buried collector region (26′) into the overlying epitaxial layer (28). The diffusion barrier (28 c) may be formed by incorporating a carbon source into the epitaxial formation of the overlying layer (28), or by ion implantation. In the case of ion implantation of carbon or SiGeC, masks (52, 62) may be used to define the locations of the buried collector regions (26′) that are to receive the carbon; for example, portions underlying eventual collector contacts (33, 44 c) may be masked from the carbon implant so that dopant from the buried collector region (26′) can diffuse upward to meet the contact (33). MOS transistors (70, 80) including the diffusion barrier (28) are also disclosed.

Abstract: We first report on the fabrication of 2 inch wafer-level GaN-based vertical light-emitting diodes (LEDs) by using a multi-functional bonding material system, which is composed of a thick Cu diffusion barrier and a bonding layer. The bonding material system superbly absorbs laser-induced stress and also effectively serves as a barrier to the indiffusion of Sn to the active region. Fully packaged vertical LEDs fabricated with indium tin oxide (ITO)/AgCu contact and the bonding material system give an operating voltage of 3.35 V at 350 mA. After over 1800 h, the operating voltages remain stable, and the reverse currents are in the range 3–8 × 10−7 A at −5 V.

Abstract: The flat panel display including the thin film transistor and the manufacturing method thereof and thin film transistor are provided to improve the electrical characteristic of device by the reducing a leakage current at the non-resistance decrease of source and drain region and channel region. The thin film transistor comprises the insulating substrate(10), the gate electrode(12), the semiconductor layer(14), the diffusion barrier(15), the second insulating layer, source and drain electrode(17a and 17b). The gate electrode is formed on the insulating substrate. The semiconductor layer is insulated with the gate electrode with the first insulating layer. The semiconductor layer provides the channel region, source and drain region. The diffusion barrier is formed on the semiconductor layer of the channel region. The second insulating layer contains the hydrogen ion(16a). The contact hole is formed so that the second insulating layer source and drain region are exposed. The source and drain electrode are contacted with source and drain region through the contact hole.

Abstract: The effectiveness of intermediate layer to prevent intermetallic diffusion is a key factor for application of Pd membranes on porous stainless steel (PSS) support. In this work, electroless-plated Pd membranes were prepared on PSS disks with two different intermediate layers: in situ oxidized metal oxide and sol−gel derived mesoporous yttria stabilized zirconia (YSZ). A thinner, gastight Pd layer can be formed on PSS support with the YSZ intermediate layer, resulting in a higher hydrogen permeance than Pd membranes on PSS support with the in situ oxidized metal oxide intermediate layer. High temperature permeation and 100-h stability tests showed that both intermediate layers were effective as the diffusion barrier for Pd membranes on PSS supports in the temperature range of 773−873 K. At temperatures above 873 K, only the YSZ intermediate layer is effective in preventing intermetallic diffusion and gives a stable Pd membrane. At the elevated temperatures Pd membranes on PSS support with in situ oxidation...

Abstract: The thermal fatigue reliability of Si die-attached joints with Zn-30wt.%Sn, high-temperature, Pb-free solder was investigated, focusing on the interfacial microstructure and joining strength of a Cu/solder/Cu joint during thermal cycling. A sound die attachment on an aluminum nitride (AlN) direct-bonded copper (DBC) substrate was achieved by forming Cu-Zn intermetallic compound (IMC) layers at the interface with the Cu of the substrate. During the thermal cycling test performed between −40°C and 125°C, thermal fatigue cracks were induced by the growth of Cu-Zn IMCs at the interface with the Cu. A␣thin titanium nitride (TiN) film was applied to suppress the formation of Cu-Zn IMCs. Adequate joint formation was accomplished by using an Au/TiN-coated DBC substrate, and only the TiN layer was observed at both interfaces. In conjunction with the TiN diffusion barrier, the Si die-attached joint created with Zn-30wt.%Sn solder exhibited a stable interfacial microstructure during thermal cycling. No microstructural changes, such as IMC formation, grain growth or formation of fatigue cracks, were observed, and the joining strength was maintained even after 2000 cycles.

Abstract: Titania and SrTi 0.7 Fe 0.3 O 3− δ sensor films were prepared by the novel aerosol deposition method at room temperature. In both cases, films with a good quality were obtained. The oxygen sensor characteristics of the devices were tested and found to be in perfect agreement with the literature. In the case of SrTi 0.7 Fe 0.3 O 3− δ in particular, the aerosol deposited films did not require the additional diffusion barrier layer needed for screen-printed films, thus simplifying fabrication. In addition, propane sensitivity was determined as a function of the film thickness for the aerosol SrTi 0.7 Fe 0.3 O 3− δ films.

Abstract: To inhibit rapid Cu diffusion in interconnect structures, an effective diffusion barrier of high thermal stability is strongly demanded. Thus in this study a nitride nanocomposite film of equimolar five-element high-entropy alloy (AlCrTaTiZr)N was developed and deposited by reactive sputtering. Thermal stability of the (AlCrTaTiZr)N film and its barrier performance to the interdiffusion of Si and Cu were investigated under thermal annealing at 700-900°C. The (AlCrTaTiZr)N film, constructed of mixed crystalline and amorphous nanocomposite structure, was found to remain thermally stable at an extremely high temperature of 900°C with low electrical resistance. Neither interdiffusion between Si and Cu through the (AlCrTaTiZr)N layer nor formation of any silicides occurred. Severe lattice distortions caused by the addition of multiprincipal elements and the nanocomposite structure of nanocrystallites surrounded by an amorphous matrix without the existence of grain boundaries were expected as the dominant factors for the high thermal stability and superior diffusion resistance of the (AlCrTaTiZr)N film as an effective barrier material.

Abstract: The interfacial reaction of Si die attachment with a high temperature lead-free solder of Zn-xSn (x = 20 wt.%, 30 wt.% and 40 wt.%) was investigated, and the currently used high temperature lead-free solder of Au-20Sn was compared. A sound die attachment to a Cu substrate can be achieved with Zn-Sn solder. No intermetallic compound (IMC) phase was observed in the solder layer, and only primary α-Zn and Sn-Zn eutectic phases were observed. At the interface with the Si die, with a metallization of Au/Ag/Ni, an AgAuZn2, IMC layer was formed along the interface, and the Ni coating layer did not react with the solder. At the interface with the Cu substrate, CuZn5 and Cu5Zn8 IMC layers were confirmed, and their thicknesses can be controlled by soldering conditions. During multiple reflows, the growth of these IMC layers was observed, but no additional voids or cracks were observed. For more reliable die attachment, a titanium nitride (TiN) coating layer was applied to suppress the formation of Cu-Zn IMCs. The Si die attached joint on the TiN-coated Cu was quite stable during the multiple reflows, and no visible IMC phase was confirmed in the interfacial microstructure.

Abstract: We have studied the formation of metal/ceramic joints by solid state bonding technique for applications at temperatures >600 ◦ C. The bonding is obtained between silicon carbide (SiC) and Ni-based super-alloy (HAYNES ® 214 TM ) via metallic foils (Ni, Ag). In some cases a thin coating on the ceramic or the alloy by the electroless JetMetal TM process has been used. Often used in brazing, nickel, when added to silicon carbide, usually give silicides. These reactions yield the “Pest Effect” (“pesting”) that induces a catastrophic brittleness of this type of assembling. To minimize the reaction of these metals with silicon carbide, addition of elements limiting the “Pest Effect” on the one hand and, diffusion barriers on the other hand, have been performed. Indeed, the choice of the thin Ni0.93 B0.07 coating is based on the ability of boron of improving the mechanical properties of silicides, thus avoiding the “Pest Effect”. However, we demonstrate that boron does not allow one to suppress the joint brittleness. Another new joining method employing a thin Ag coating or a Ag foil was tested. This process revealed the absence of chemical reaction at the Ag/SiC interface, thus proving the beneficial role of silver, which acts as an effective diffusion barrier for nickel beyond a certain thickness. This method has led to fabrication of joints presenting high shear resistance (>40 MPa).

Abstract: X-ray absorption fine structure spectroscopy has been used to study the chemical and structural properties of self-forming diffusion barrier layers from Cu-8 at. % Mn alloy films on porous low-k and thermally grown SiO2 dielectrics. For the porous low-k/Cu(Mn) system, we provide evidence that the interface is composed of MnSiO3 and MnO with near complete Mn segregation from the alloy film; however, we find that the self-forming process does not go to full completion on thermally grown SiO2 substrates.

Abstract: Described herein is the use of a diffusion barrier layer between metallic layers in MEMS devices. The diffusion barrier layer prevents mixing of the two metals, which can alter desired physical characteristics and complicate processing. In one example, the diffusion barrier layer may be used as part of a movable reflective structure in interferometric modulators.

Abstract: In the present paper, the diffusion barrier properties of amorphous and nanocrystalline (NC) Ta films, and the interface microstructure of Ta/Cu were investigated as a function of annealing temperature. X-ray diffraction, scanning electron microscopy, cross-sectional transmission electron microscopy, and energy-dispersive spectrometer line scans were employed to study the microstructure evolution and diffusion behavior. It was found that an amorphous layer with a thickness of ∼5 nm formed at the interface of NC Ta/Cu at 450 °C annealing, while the interface of amorphous-Ta/Cu was still abrupt. Moreover, amorphous-Ta film acts as an effective diffusion barrier up to temperatures of 650 °C, which is higher than that for NC-Ta film. The fast diffusion along grain boundaries inside NC-Ta films is suggested to be responsible for the main failure of NC-Ta film.

Abstract: A novel plasma-enhanced atomic layer deposition-grown mixed-phase/nanolaminate Ru–TaN barrier has been investigated, and it was confirmed that the copper diffusion barrier and direct-plate characteristics of the mixed-phase barrier can be modulated by varying the metal ratio in the film This liner was subsequently optimized to yield a composition that combines the robust barrier properties of TaN with direct-plate characteristics of Ru It was found that the deposited multicomponent system consists of individual crystalline and amorphous phase regions distributed across the barrier The resulting optimized mixed-phase barrier was found to exhibit excellent copper diffusion barrier characteristics in layers as thin as 2 nm A high degree of (111) texture (>84%) was observed for the direct-plated copper on this Ru–TaN barrier, which was very similar to the electroplated Cu deposited on a physical vapor deposition copper-seed control sample Additionally, the filling characteristics in sub-50-nm features we

Abstract: The nitridation process of Eu-doped AEAlSi (AE=Ca and/or Sr) was investigated by thermogravimetry–differential thermal analysis to improve the method for synthesis of AEAlSiN3:Eu2+ nitride phosphors. The nitridation reactivity was dependent on alkaline earth elements. For SrxEuyCa1−x−yAlSi with a high Sr content, nitridation proceeded efficiently at 1100°–1150°C, close to the melting point of the intermetallic compounds. As nitridation of Si or Al intermetallics usually proceeds via the diffusion-controlled surface reaction, sudden rupture of the diffusion barrier, the surface nitride layer, at the melting point could cause a marked change in the reaction rate and dependence on nitrogen partial pressure. The order of reactivity at temperatures close to the melting point agreed with the order of vapor pressure of alkaline earth elements at the melting point. A highly efficient process for large-scale production of SrxCa1−xAlSiN3:Eu2+ phosphor was developed taking advantage of the characteristic nitridation reaction at the melting point.

Abstract: The underlying physical mechanism of the so-called colossal dielectric constant phenomenon in CaCu3Ti4O12 (CCTO) thin films were investigated by using semiconductor theories and methods. The semiconductivity of CCTO thin films originated from the acceptor defect at a level ∼90 meV higher than valence band. Two contact types, metal-semiconductor and metal-insulator-semiconductor junctions, were observed and their barrier heights, and impurity concentrations were theoretically calculated. Accordingly, the Schottky barrier height of metal-semiconductor contact is about 0.8 eV, and the diffusion barrier height of metal-insulator-semiconductor contact is about 0.4–0.7 eV. The defect concentrations of both samples are quite similar, of the magnitude of 1019 cm−3, indicating an inherent feature of high defect concentration.

Abstract: Experimental data on the migration of Cu impurities in TiN and in similar diffusion-barriers used in electronic devices have led to conflicting suggestions about the underlying physical mechanisms. Here we use results of first-principles calculations, which are in agreement with measured activations energies, to elucidate the atomic-scale processes of moderate and rapid diffusion of Cu through the bulk and intergrain voids of TiN films, respectively. We also find that O and H impurities are fast diffusers in TiN. The results offer an assessment for the efficiency of TiN diffusion-barriers with respect to properties, such as nature of impurities, stoichiometry, and crystallinity.

Abstract: The growth behavior of B4C interlayers deposited at the interfaces of Mo/Si multilayers was investigated using x-ray photoemission spectroscopy, x-ray reflectivity, and x-ray diffraction measurements. We report an asymmetry in the formation of B4C at the B4C-on-Mo interface compared to the B4C-on-Si interface. X-ray photoelectron spectroscopy (XPS) depth profiling shows that for B4C-on-Mo the formed stoichiometry is close to expectation (4∶1 ratio), while for B4C-on-Si it is observed that carbon diffuses from the B4C interfaces into the multilayer, resulting in nonstochiometric growth (>4∶1). As a result, there is a discrepancy in the optical response near 13.5 nm wavelength, where B4C-on-Mo behaves according to model simulations, while B4C-on-Si does not. The as-deposited off-stoichiometric B4C-on-Si interface also explains why these interfaces show poor barrier properties against temperature induced interdiffusion. We show that the stoichiometry of B4C at the Mo-Si interfaces is connected to the structure of the layers onto which B4C is grown. Because of enhanced diffusion into the amorphous Si surface, we suggest that deposited boron and carbon atoms form SiXBY and SiXCY compounds. The low formation enthalpy of SiXCY ensures C depletion of any BXCY interlayer. Only after a saturated interfacial layer is formed, does further deposition of boron and carbon atoms result in actual B4C formation. In contrast to the off-stoichiometric B4C growth on top of Si, B4C grown on top of Mo retains the correct stoichiometry because of the higher formation enthalpies for MoXBY and MoXCY formation and the limited diffusion depth into the (poly)-crystalline Mo surface.

Abstract: To inhibit rapid Cu diffusion in interconnect structures, an effective diffusion barrier of high thermal stability is strongly demanded. Thus in this study a nitride nanocomposite film of equimolar five-element high-entropy alloy (AlCrTaTiZr)N was developed and deposited by reactive sputtering. Thermal stability of the (AlCrTaTiZr)N film and its barrier performance to the interdiffusion of Si and Cu were investigated under thermal annealing at 700-900°C. The (AlCrTaTiZr)N film, constructed of mixed crystalline and amorphous nanocomposite structure, was found to remain thermally stable at an extremely high temperature of 900°C with low electrical resistance. Neither interdiffusion between Si and Cu through the (AlCrTaTiZr)N layer nor formation of any silicides occurred. Severe lattice distortions caused by the addition of multiprincipal elements and the nanocomposite structure of nanocrystallites surrounded by an amorphous matrix without the existence of grain boundaries were expected as the dominant factors for the high thermal stability and superior diffusion resistance of the (AlCrTaTiZr)N film as an effective barrier material.

Abstract: A sputter-prepared Ru (7 nm)/WN x (8 nm) stacked layer was investigated as a diffusion barrier layer between Cu and Si for direct-plateable Cu interconnects, and its performance was compared with that of a Ru single layer with the same thickness (15 nm). X-ray diffractometry and sheet resistance measurements showed that the incorporation of WN x into the Ru single layer system significantly improved the barrier performance against Cu diffusion. The Ru/WN, bilayer barrier stack failed due to Cu diffusion attack after annealing at 750°C for 30 min, while the Ru single layer failed after annealing at 450°C by the formation of Cu silicide (η"-Cu 3 Si). A high resolution transmission electron microscopy analysis clearly suggested that this was due to the excellent diffusion barrier performance of WN x film with a nanocrystalline structure embedded in an amorphous matrix.