Microelectronics International

Maryam Amirhoseiny; Zainuriah Hassan; Sha Shiong Ng

2013 Microelectronics International

doi: 10.1108/13565361311314430

Purpose – The purpose of this paper was to investigate the growth dependence of InN on Si substrate with different orientation through RF reactive magnetron sputtering in ambient temperature. Design/methodology/approach – The authors fabricated indium nitride (InN) thin films by radio frequency (RF) sputtering. The InN thin films were deposited on Si (100), Si (110) and Si (111) substrates at room temperature. The crystalline structure and surface morphology of the InN films were characterized by X‐ray diffraction (XRD), scanning electron microscope (SEM), energy‐dispersive X‐ray spectroscopy (EDX) and atomic force microscopy (AFM). Findings – X‐ray diffraction results revealed that the wurtzite InN with preferential (101) orientation are deposited. Through the Scherrer structural analysis revealed nanocrystalline structure for InN films grown on Si (110), Si (100) and Si (111) orientation with crystallite size of 42.3, 33.8 and 24.1, respectively. The optical properties of InN layers were examined by Fourier transform infrared (FTIR) and micro‐Raman reflectance spectroscopy at room temperature. The observation of the E1(TO), A1(LO), and E2(high) phonon modes of the InN from the IR and Raman results confirmed that the deposited InN thin film has hexagonal structure. Originality/value – Si (110) surface is not isotropic and it may offer a unique orientation plane for the nitride films which could reduce the defect density and the resulting tensile stress responsible for film cracking. Therefore, it is absolutely worth exploring the growth of InN on Si (110) by using relatively simple and cheap reactive sputtering technique.

T.S. Dhahi; U. Hashim; M.E. Ali

2013 Microelectronics International

doi: 10.1108/13565361311314449

Purpose – The purpose of this paper was to systematically study the electrical properties of 5‐, 42‐ and 75‐nm gap polysilicon structures to evaluate the potentiality of these structures to be used in biomolecular sensing devices. Design/methodology/approach – The authors previously reported the fabrication and morphological characterization of these structures. In this report, they electrically probed the presence of nanogap through current measurement. The effects of electrolytes on the capacitance profiles of these structures were systematically studied with air, water and various dilutions of phosphate buffer saline. Findings – An increment in capacitance was found with the increment in electrolyte concentration. Improvement in current flow, capacitance, permittivity, and conductivity were observed with the smaller size nanogaps, suggesting their applications in low power consuming devices. Originality/value – Since nanogap‐based dielectric biosensing devices need to be operated with a low level of current to avoid biomolecular damage, these structures should have potential applications in dielectric‐based biomolecular detection using a low cost dielectric analyser.

Kostja Makarovič; Anton Meden; Marko Hrovat; Darko Belavič; Janez Holc; Marija Kosec

2013 Microelectronics International

doi: 10.1108/13565361311314458

Purpose – In this manuscript the purpose is to present and evaluate the developed non‐destructive method for analysing the phase composition of LTCC Du Pont “Green Tape 951” material fired in the temperature range from 800 to 1,000°C using X‐ray powder diffraction and Rietveld refinement. Design/methodology/approach – The method uses the crystalline Al2O3 which is already present in the material as an internal standard since its mass fraction was previously found to be constant in the described temperature range. Findings – The results of the non‐destructive analyses and the classical destructive analyses are comparable and the estimated error of the destructive phase analyses and the calculated errors for the non‐destructive phase analyses are of the same order. Practical implications – The described method can be used also for analysing another type of LTCC material. In this case it is necessary to check whether the mass fraction of any crystalline phase present in the sample is constant in the given temperature range, because only in this case can it be used as an internal standard for a determination of the phase composition. Originality/value – The non‐destructive method is a fast and easy approach for analysing the fired samples and is also suitable for controlling the phase composition of LTCC materials on 3D complex structures without destroying them, just by using the X‐ray diffraction patterns collected from their surface.

Shanmugan Subramani; Teeba Nadarajah; Mutharasu Devarajan

2013 Microelectronics International

doi: 10.1108/13565361311314467

Purpose – Surface configuration at the interface between two materials makes a huge difference on thermal resistance. Thermal transient analysis is a powerful tool for thermal characterization of complex structures like LEDs. The purpose of this paper is to report the influence of surface finish on thermal resistance. Design/methodology/approach – Surface of heat sink was modified into two categories: machined as channel like structure; and polished using mechanical polisher and tested with 3W green LED for thermal resistance analysis. Findings – The observed surface roughness of rough and polished surface was 44 nm and 4 nm, respectively. Structure function analysis was used to determine the thermal resistance between heat sink and MCPCB board. The observed thermal resistance from junction to ambient (R thJA ) value measured with thermal paste at 700 mA was lower (34.85 K/W) for channel like surface than rough surface (36.5 K/W). The calculated junction temperature ( T J ) for channel like surface and polished surface was 81.29°C and 85.24°C, respectively. Research limitations/implications – Channelled surface aids in increasing bond line thickness. Surface polishing helps to reduce the air gaps between MCPCB and heat sink and also to increase the surface contact conductance. Practical implications – The proposed method of surface modification can be easily done at laboratory level with locally available techniques. Originality/value – Much of the available literature is only concentrating on the design modification and heat transfer from fins to ambient. There was little research on modification of top surface of the heat sink and the proposed concept would give good results and also it will make the material cost reduction as well as material too.

S.N. Mathad; R.N. Jadhav; Vijaya Puri

2013 Microelectronics International

doi: 10.1108/13565361311314476

Purpose – The purpose of this paper was to determine the complex permittivity of bismuth strontium manganites (Bi 1−x Sr x MnO 3 ) in the 8‐12 GHz range by using perturbation of Ag thick film microstrip ring resonator (MSRR) due to superstrate of both bulk and thick film. Design/methodology/approach – The BSM ceramics were synthesized by simple low cost solid state reaction method and their fritless thick films were fabricated by screen printing technique on alumina substrate. A comparison has been made between the X band response of Ag thick film microstrip ring resonator due to perturbation of bulk and thick film Bi 1−x Sr x MnO 3 ceramic. Findings – The bulk and thick film superstrate decreases the resonance frequency of MSRR. In this technique even minor change in the properties of superstrate material changes the MSRR response. Variation of strontium content also influences microwave conductivity and penetration depth of bulk and thick films. Originality/value – The microwave complex permittivity decreases with increase in Sr content in bismuth manganite and it is higher for bulk as compared to its thick films. The superstrate on Ag thick film microstrip ring resonator is an efficient tool capable of detecting the composition dependent changes in microwave properties of ceramic bulk and thick films.

J.K. Atkinson; M. Glanc; M. Prakorbjanya; M. Sophocleous; R.P. Sion; E. Garcia‐Breijo

2013 Microelectronics International

doi: 10.1108/13565361311314485

Purpose – The purpose of this paper is to report thick film environmental and chemical sensor arrays designed for deployment in both subterranean and submerged aqueous applications. Design/methodology/approach – Various choices of materials for reference electrodes employed in these different applications have been evaluated and the responses of the different sensor types are compared and discussed. Findings – Results indicate that the choice of binder materials is critical to the production of sensors capable of medium term deployment (e.g. several days) as the binders not only affect the tradeoff between hydration time and drift but also have a significant bearing on device sensitivity and stability. Sensor calibration is shown to remain an issue with long‐term deployments (e.g. several weeks) but this can be ameliorated in the medium term with the use of novel device fabrication and packaging techniques. Originality/value – The reported results indicate that is possible through careful choice of materials and fabrication methods to achieve near stable thick film reference electrodes that are suitable for use in solid state chemical sensors in a variety of different application areas.

Yap Boon Kar; Noor Azrina Talik; Zaliman Sauli; Foong Chee Seng; Tan Chou Yong; Vithyacharan Retnasamy

2013 Microelectronics International

doi: 10.1108/13565361311314502

Purpose – This paper aims to discuss the effects of ionic contaminations on the die surface of high lead flip chip ball grid array (FCBGA) package. Ionic contaminations from the flux residue, formed during the die attachment process, could affect the package long‐term performance. Design/methodology/approach – Thus, the flux‐cleaning process was implemented and the cleanliness effect was evaluated. Cleaning experiments using a new water‐based solvent were carried out to investigate the flux‐cleaning efficiency. The test packages were then evaluated via ion chromatography (IC). Findings – Ion chromatograms show that there are high levels of ionic elements detected prior to the cleaning process. After the cleaning process, the contamination levels reduced significantly. Originality/value – The value of the work here is testing of the new environmental friendly water‐based MPC ® cleaning efficiency. The reduction of ionic contamination is thus reported.