T. Osipowicz

Improvement of dielectric loss tangent of Al2O3 doped Ba0.5Sr0.5TiO3 thin films for tunable microwave devices

Al2O3 doped Ba0.5Sr0.5TiO3 (BST) thin films, with different Al2O3 contents, were deposited on (100) LaAlO3 substrates by the pulsed laser deposition technique to develop agile thin films for tunable microwave device applications. The dielectric properties of Al2O3 doped BST films were determined with a nondestructive dual resonator near 7.7 GHz. We demonstrated that the Al2O3 doping plays a significant role in improving the dielectric properties of BST thin films. The Al2O3 doping successfully reduced the dielectric loss tangent (tan δ) from 0.03 (pure BST) to 0.011 (Al2O3 doped BST). Reduction in the loss tangent also leads to reduction in the dielectric constant and dielectric tunability. Our results showed that the BSTA4 film remains tunability=15.9%, which is sufficient for tunable microwave devices applications. Consequently, the Al2O3 doping improved the figure of merit (K) for the BST films from K=7.33 (pure BST) to K=14.45 (Al2O3 doped BST).

The National University of Singapore nuclear microscope facility

Abstract The National University of Singapore nuclear microscope facility is based around a HVEC AN2500 single ended Van de Graaff accelerator and an Oxford Microbeams coupled quadrupole triplet focusing system. Particle induced X-ray emission (PIXE), nuclear or Rutherford backscattering spectrometry (RBS) and scanning transmission ion microscopy (STIM) can be carried out simultaneously. Data acquisition is carried out using a simple but flexible PC based system (Oxford Microbeams DAQ) and the data is analysed using a combined RUMP and GUPIX PC based interactive package (NUSDAN) acting under WINDOWS. Resolution tests using a calibration grid and a multi layer integrated circuit have shown the facility to be capable of 600 nm spot sizes for 2 MeV protons at currents suitable for microanalysis.

Micro‐Raman Spectroscopy Investigation of Nickel Silicides and Nickel (Platinum) Silicides

The formation of silicides has been successfully monitored by Raman spectroscopy. silicides formed at different annealing temperatures using rapid thermal annealing were analyzed using Rutherford backscattering spectroscopy and X‐ray diffraction. Raman spectroscopy was further used to examine these samples. The results showed that Raman spectroscopy could accurately identify the phases of silicides formed at various temperatures. These findings were used to demonstrate the increased thermal stability of by the addition of . This study demonstrates the applicability of Raman spectroscopy for monitoring the formation of . which was suggested to be the future silicide for deep submicrometer integrated circuit processing. Raman spectroscopy offers a unique tool for phase identification at localized areas and mapping characterization of silicides with micrometespatial resolution. ©2000 The Electrochemical Society

Micromachining using deep ion beam lithography

Abstract In recent years the process combining deep X-ray lithography with electroforming and micromoulding (i.e. LIGA), has become an important technique for the production of high aspect-ratio microstructures for the fabrication of micro-electromechanical systems (MEMS). The aim of this paper is to investigate the potential of high energy ion microbeams for carrying out similar micromachining, and in particular for overcoming the geometrical restrictions which are inherent in deep x-ray lithography. Using a scanned 2.0 MeV proton beam of approximately 1 micron diameter, we produced latent microstructures in high molecular weight PMMA resist. These resist microstructures were subsequently developed using a multi-component developer which is highly specific in the removal of exposed resist, while leaving unexposed or marginally exposed material unaffected. A suitable range of exposures has been established, and factors affecting the geometrical fidelity of the produced microstructure have been investigated. The relative advantages and limitations of this technique vis a vis deep X-ray lithography are discussed.

Formation and Thermal Stability of Nickel Germanide on Germanium Substrate

The formation and thermal stability of nickel germanide on germanium substrate were examined by both electrical and physical characterization methods. Low resistivity (14 µΩ cm) mono-nickel–germanide was formed at a low temperature of 400°C on Ge substrate. The sheet resistance of nickel germanide changed with the germanide formation temperatures and had a similar characteristic as nickel silicide. However, the thermal stability study shows that NiGe formed on Ge substrate has a poorer thermal stability than NiSi on Si substrate, which is due to the lower activation energy of agglomeration in NiGe (2.2±0.2 eV) compared to NiSi.

Resist materials for proton micromachining

Abstract The production of high aspect ratio microstructures is a potential growth area. The combination of deep X-ray lithography with electroforming and micromolding (i.e. LIGA) is one of the main techniques used to produce 3D microstructures. The new technique of proton micromachining employs focused MeV protons in a direct write process which is complementary to LIGA, e.g. micromachining with 2 MeV protons results in microstructures with a height of 63 μm and lateral sub-micrometer resolution in PMMA resist. The aim of this paper is to investigate the capabilities of proton micromachining as a lithographic technique. This involves the study of different types of resists. The dose distribution of high molecular weight PMMA is compared with three other types of resist: First the positive photo resist AZ P4620 will be discussed and then PMGI SF 23, which can be used as a deep UV, e-beam or X-ray resist. Finally SU-8, a new deep UV negative type of chemically amplified resist will be discussed. All these polymers are applied using the spin coating technique at thicknesses of between 1 and 36 μm

Novel Epitaxial Nickel Aluminide-Silicide with Low Schottky-Barrier and Series Resistance for Enhanced Performance of Dopant-Segregated Source/Drain N-channel MuGFETs

We have developed a novel epitaxial nickel-aluminide silicide (NiSi_2-xAl_x) to reduce the Schottky-barrier height (SBH) and series resistance in n-channel MuGFETs with dopant-segregated Schottky-Barrier source/drain (DSS). 10% substitutional incorporation of Al in the Si matrix at the silicide-Si interface leads to a 37% reduction in the intrinsic SBH of nickel silicide. A further 42% effective reduction in the DSS SBH was attained with the combination of NiSi_2-xAl_x and DSS technology. Saturation drive current enhancement of 94% for NiSi_2-xAl_x DSS MuGFETs over NiSi DSS MuGFETs was achieved, attributed to SBH lowering, series resistance reduction and possibly silicide strain effects. As a result, an excellent drive current of 882 muA/mum at V_GS-V_T =V_DS = 1.2 V was achieved for NiSi_2-xAl_xDSS MuGFETs with 55 nm gate length.

Micromachining using focused high energy ion beams: Deep Ion Beam Lithography

Abstract The combination of deep X-ray lithography with electroforming and micromoulding (i.e., LIGA) has been shown to offer high potential for the production of high aspect-ratio microstructures. The LIGA technique, employing synchrotron light and a suitable X-ray mask, allows production of 3D microstructures in PMMA with aspect ratios around 100. Here we demonstrate that the novel technique of Deep Ion Beam Lithography (DIBL), a direct process utilizing a focused beam of MeV ions scanned in a predetermined pattern over a suitable resist material, can produce three dimensional microstructures with sub-micrometer feature sizes. Microstructures extending up to 100 μm from the substrate with aspect ratios approaching 100 can be produced. Multiple exposures at different ion energies allow production of multilayer structures in single resist layers of SU-8, a newly developed, chemically accelerated, negative tone, near UV, photoresist.

Structural and photoluminescence properties of Gd implanted ZnO single crystals

We present the structural and photoluminescence properties of 30 keV gadolinium implanted and subsequently annealed zinc oxide (ZnO) single crystals. Rutherford backscattering and channeling results reveal a low surface region defect density which was reduced further upon annealing. For low implantation fluence, around 85% of the Gd atoms are estimated to be in sites aligned with the ZnO lattice, while for higher fluences the Gd is largely disordered and likely forms precipitates. The Raman spectra of the implanted samples show defect-induced modes, which match the one-phonon density of states for the most heavily implanted samples. Annealing eliminates these features implying the removal of Gd-associated lattice disorder. Low temperature photoluminescence spectra revealed a red-shift in the defect emission, from green to orange/yellow, indicating the suppression of a deep level, which is thought to be due to oxygen vacancies. It is suggested that the orange/yellow emission is unmasked when the green emis...

Diamond-like film as a corrosion protective layer on the hard disk

A magnetic layer based on Co-alloys does not possess the necessary mechanical durability and corrosion resistance and must be covered with a protective layer. An accelerated electrochemical test has been conducted on a hard disk magnetic layer covered with amorphous hydrogenated carbon doped with nitrogen. From the potentiodynamic and DC polarization measurements of the corrosion current in a 0.15 M NaCl solution adjusted to different pH, it was concluded that an acid environment can largely decrease the reliability and lifetime of a hard disk. Lubricant can contribute to corrosion protection by covering voids and other overcoat imperfections and prevent water vapor penetration into the magnetic film. Atomic force microscope images show localized distribution of corrosion sites with a density of 1.2 £ 10 6 defects/cm 2 . The overcoat also prevents a lateral spread of the corrosion products across a disk. q 2000 Elsevier Science S.A. All rights