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Passivation Layer (passivation + layer)

Distribution by Scientific Domains
Physics and Astronomy72%

Selected Abstracts

Void formation in the Cu layer during thermal treatment of SiNx/Cu/Ta73Si27/SiO2/Si systems

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 1-2 2005
R. Hübner
Abstract The thermal stability of a SiNx passivation layer and its influence on the annealing behavior of an amorphous Ta73Si27 diffusion barrier deposited between copper and SiO2 were analyzed by X-ray diffraction, glow discharge optical emission spectroscopy, Auger electron spectroscopy, scanning electron microscopy, and transmission electron microscopy. During heat treatment at a temperature Tan = 500 °C, diffusion of Cu atoms out of the Cu metallization into the SiNx passivation occurs. The Cu diffusion intensifies with increasing annealing temperature and annealing time and seems to be a necessary precondition for a defect formation process observed within the Cu metallization. Depending on the chemical composition of the SiNx/Cu interface, voids in the ,m-range can be formed within the Cu film. Compared to an unpassivated sample, heat treatment leads to a reduced diffusion of Ta atoms from the barrier through the copper into the SiNx/Cu interface. The barrier crystallization process into Ta5Si3 occurring during annealing at Tan = 600 °C is principally not affected by the presence of a SiNx passivation. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Dual-Gate Organic Field-Effect Transistors as Potentiometric Sensors in Aqueous Solution

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2010
Mark-Jan Spijkman
Abstract Buried electrodes and protection of the semiconductor with a thin passivation layer are used to yield dual-gate organic transducers. The process technology is scaled up to 150-mm wafers. The transducers are potentiometric sensors where the detection relies on measuring a shift in the threshold voltage caused by changes in the electrochemical potential at the second gate dielectric. Analytes can only be detected within the Debye screening length. The mechanism is assessed by pH measurements. The threshold voltage shift depends on pH as ,Vth,=,(Ctop/Cbottom),×,58,mV per pH unit, indicating that the sensitivity can be enhanced with respect to conventional ion-sensitive field-effect transistors (ISFETs) by adjusting the ratio of the top and bottom gate capacitances. Remaining challenges and opportunities are discussed. [source]

Enhanced Performance of Fullerene n-Channel Field-Effect Transistors with Titanium Sub-Oxide Injection Layer

ADVANCED FUNCTIONAL MATERIALS, Issue 9 2009
Shinuk Cho
Abstract Enhanced performance of n-channel organic field-effect transistors (OFETs) is demonstrated by introducing a titanium sub-oxide (TiOx) injection layer. The n-channel OFETs utilize [6,6]-phenyl-C61 butyric acid methyl ester (PC61BM) or [6,6]-phenyl-C71 butyric acid methyl ester (PC71BM) as the semiconductor in the channel. With the TiOx injection layer, the electron mobilities of PC61BM and PC71BM FET using Al as source/drain electrodes are comparable to those obtained from OFETs using Ca as the source/drain electrodes. Direct measurement of contact resistance (Rc) shows significantly decreased Rc values for FETs with the TiOx layer. Ultraviolet photoelectron spectroscopy (UPS) studies demonstrate that the TiOx layer reduces the electron injection barrier because of the relatively strong interfacial dipole of TiOx. In addition to functioning as an electron injection layer that eliminates the contact resistance, the TiOx layer acts as a passivation layer that prevents penetration of O2 and H2O; devices with the TiOx injection layer exhibit a significant improvement in lifetime when exposed to air. [source]

Optimisation of surface passivation for highly reliable angular AMR sensors

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2010
M. Isler
Abstract For state-of-the-art angular sensors based on the anisotropic magnetoresistive (AMR) effect in NiFe layers, the angular accuracy over time is limited by a drift of the offset voltage of the Wheatstone bridge configuration. It is shown that the interaction of the passivation layer and the magnetic permalloy is crucial for the drift of the offset voltage. By investigating the time and temperature dependence, the offset drift is attributed to stress relief of the PECVD passivation layer due to microstructural changes. Hydrogen outdiffusion from the passivation layer is involved in the observed stress evolution. It is demonstrated that optimising the passivation layer composition as well as the time of the subsequent annealing is beneficial for stress stabilisation of the permalloy-passivation layer system. With this optimised passivation layer a significant offset drift reduction of the NiFe Wheatstone bridge has been achieved resulting in highly accurate and long-term stable angular AMR sensors. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Processing approaches of AlGaN/GaN Metal Insulator Semiconductor Hetero Field Effect Transistors (MISHFET) on Si (111) substrates

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009
Martin Eickelkamp
Abstract We report on the fabrication of AlGaN/GaN MISHFETs using SiO2 and SiN as gate dielectrics. In particular, two different passivation procedures are investigated with respect to the resulting electrical properties. A fluorine based ICP etch step, as used here to remove the gate dielectric prior to passivation layer deposition, is shown to deteriorate the sheet carrier concentration and mobility. Depositing the passivation layer upon the gate dielectric, on the other hand, slightly decreases the sheet resistance as compared to a conventional HFET. Gate diode characteristics reveal significant reduction of gate leakage currents in both, reverse and forward biasing regions, of 1-2 and up to 6 orders of magnitude, respectively. All devices exhibit more pronounced current collapse compared to a conventional passivated HFET. In addition, a clear depencency on the processing scheme is observed. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

High drain current and low on resistance normally-off-mode AlGaN/GaN junction HFETs with a p-type GaN gate contact

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008
T. Fujii
Abstract The normally-off-mode junction HFETs with a p-type GaN gate contact showing high drain current and an extremely large on/off ratio were successfully fabricated by MOVPE. The drain currents were found to be very sensitive to the surface of the u-AlGaN barrier exposed by RIE etching. A reproducible and stable high drain current was achieved using a very thin SiN passivation layer. The maximum drain current was 1.58×10,1 A/mm at VGS = 4 V, while the drain current at VGS = 0 V was as low as 1.45×10,8 A/mm. Therefore, an on/off ratio of 107 has been achieved. The sub-threshold swing was as small as 90 mV/dec.. The on resistance was 3.4 m,cm2, the threshold voltage was +0.45 V, and the breakdown voltage was over 325 V. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Properties of MBE CdxHg1,xTe/GaAs structures modified by ion-beam milling

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2004
V. V. Bogoboyashchyy
Abstract Modification of electrical properties of n - and p -type MBE mercury,cadmium-telluride (MCT) structures with passivation gradient band gap layers under ion milling was investigated. Main features of the CdxHg1,xTe electrical properties modification with such treatment also hold for MBE MCT structures in comparison with bulk samples. It is shown that a significant decrease of the p,n conversion rate for such structures in comparison with homogeneous bulk samples at other equal conditions is caused by the presence of the wide band gap passivation layer. The diffusion-like character of the p,n conversion front movement is confirmed. The nature of additional "heavy" electrons in MBE structures is proposed. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Fabrication of AlGaN/GaN MIS-HFET using an Al2O3 high k dielectric

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2003
Ki-Yeol Park
Abstract We report on a metal,insulator,semiconductor AlGaN/GaN heterostructure field-effect transistor (MIS-HFET) using Al2O3 simultaneously for channel passivation layer and as a gate insulator which was deposited by plasma enhanced atomic layer deposition(PE-ALD). Capacitance,voltage measurements show successful surface passivation by the Al2O3 dielectric layer. For a gate length 1.2 ,m with 15 ,m source-to-drain spacing the maximum drain current was 1.22 A/mm, the maximum transconductance was 166 mS/mm and the gate leakage current was 4 nA/mm at Vgs = ,20 V which is at least three orders of magnitude lower than that of conventional AlGaN/GaN HFETs. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Simple Patterning via Adhesion between a Buffered-Oxide Etchant-Treated PDMS Stamp and a SiO2 Substrate,

ADVANCED FUNCTIONAL MATERIALS, Issue 13 2007
Y.-K. Kim
Abstract A very simple polydimethylsiloxane (PDMS) pattern-transfer method is devised, called buffered-oxide etchant (BOE) printing. The mechanism of pattern transfer is investigated, by considering the strong adhesion between the BOE-treated PDMS and the SiO2 substrate. PDMS patterns from a few micrometers to sub-micrometer size are transferred to the SiO2 substrate by just pressing a stamp that has been immersed in BOE solution for a few minutes. The patterned PDMS layers work as perfect physical and chemical passivation layers in the fabrication of metal electrodes and V2O5 nanowire channels, respectively. Interestingly, a second stamping of the BOE-treated PDMS on the SiO2 substrate pre-patterned with metal as well as PDMS results in a selective transfer of the PDMS patterns only to the bare SiO2. In this way, the fabrication of a device structure consisting of two Au electrodes and V2O5 nanowire network channels is possible; non-ohmic semiconducting I,V characteristics, which can be modeled by serially connected percolation, are observed. [source]

Metastability in multicomponent oxide transistors

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2010
Warren B. Jackson
Abstract Results of an investigation of bias stress metastability of multicomponent, zinc,indium and zinc,tin oxides, transistors are investigated. The bias stress as a function of various dielectrics, passivation layers, and illumination conditions indicate that for negative gate bias stressing defects often are created in the semiconductor, probably near or at the surface, particularly if the devices are unpassivated. Oxygen vacancy formation is a likely candidate. For many dielectrics, the positive gate bias metastability appears to be dominated by charge trapping within the insulator. For zinc,tin oxide devices, the kinetics of the metastability follows a stretched exponential behavior with a power law dependence on gate voltage. Correcting for the observed Meyer,Neldel behavior, the activation energy of , is about 1.2,eV for defect generation and the disorder energy from , is about 0.06,eV. By using passivation, the best gate dielectrics and annealing protocols, we have reduced the bias stress metastability to about 0.1,V for a 25,000,s stress at 22,°C. [source]