Microelectronics International

Arshak, K.; Arshak, A.; Jafer, E.; Waldern, D.; Harris, J.

2007 Microelectronics International

doi: 10.1108/13565360810846581

Purpose To develop a wireless sensor microsystems containing all the components of data acquisition system, such as sensors, signalconditioning circuits, analogdigital converter, embedded microcontroller unit MCU, and RF communication modules. This has now become the focus of attention in many biomedical applications.Designmethodologyapproach The system prototype consists of miniature FSK transceiver integrated with MCU in one small package, chip antenna, and capacitive interface circuitry based on Deltasigma modulator. At the base station side, an FSK receivertransmitter is connected to another MCU unit, which send the received data or received instructions from a PC through a graphical user interface GUI. Industrial, scientific and medical band RF 433MHz was used to achieve half duplex communication between the two sides. A digital filtering has been used in the capacitive interface to reduce noise effects forming capacitance to digital converter. All the modules of the mixed signal system are integrated in a printed circuit board of size 22.4620.168mm.Findings An innovation circuits and system techniques for building advanced smart medical devices have been discussed. Lowpower consumption and high reliability are among the main criteria that must be given priority when designing such wirelessly powered microsystems. Switched capacitors readout circuits have been found to be suitable for pressure sensing lowpower applications.Research limitationsimplications The presented wireless prototype needs a second phase of development that will lead to a further reduction in both size and power consumption. Currently, the main limitation of the RF system is the number of working hours according to the selected battery.Practical implications The developed system was found to be useful in terms of measuring pressure and temperature in a system of either slow or fast physical change. It would be a good idea to explore the system performance in human or animal trials.Originalityvalue This paper fulfils useful information for capacitive interface circuitries and presents a new shortrange wireless system that has different design features.

Tong, MingSze; Chang, TaeGyu; Sauleau, Ronan

2007 Microelectronics International

doi: 10.1108/13565360810846590

Purpose To perform studies and comparisons on the electromagnetic bandgap EBG structures, which are constructed by using a combination of inductive and capacitive elements printed on guidedwave transmission lines, and by applying a chirpingandtapering technique.Designmethodologyapproach An inhouse solver based on finitedifference timedomain FDTD method is adopted for analysis. Conventionally, EBG characteristics are formed by a series of perforations, considered as capacitive elements, on the ground planes. To enhance the performance, an additional inductive element is implemented, which is realized by narrowing the strip over the respective perforated regions. For further enhancement, a chirpingandtapering technique is applied on the combined EBG structures for comparisons.Findings Through scattering parameter analysis, it was found that the EBG structures using combined inductive and capacitive elements exhibit a bandgap behavior superior to the ones built with only inductive or capacitive elements. In another set of comparisons, the modified EBG structures combined with a chirpingandtapering technique resulted in further widening of bandgap, as well as lower sidelobes and a smoother transition towards the bandgap region.Research limitationsimplications Research was mainly limited to studying solely the EBG structures printed on guidedwave transmission lines.Practical implications The proposed EBG structures may be applied into various areas, such as microelectronics and mobile communications for harmonic suppressions, and into other practical electronic circuit structures.Originalityvalue The ideas on applying combined inductive and capacitive elements on various guidedwave transmission lines to induce EBG characteristics, together with applications of a chirpingandtapering technique on the combined EBG structures give rise to the research originality.

Salame, C.; Habchi, R.

2007 Microelectronics International

doi: 10.1108/13565360810846608

Purpose The purpose of this paper is to discuss the temperature failure effect on electronic components and their electrical parameters variation.Designmethodologyapproach The MOSFET device parameters analysis was done by numerical analysis based on a double exponential model using the integrated pn junction.Findings The temperature dependence of these parameters is investigated their evolution allows the evaluation of device's operation reliability in hightemperature environments.Originalityvalue The paper demonstrates how the temperature affect the normal operation of the electronic device and the model accuracy is investigated at high temperature.

Vhanakhande, B.B.; Jadhav, S.V.; Puri, Vijaya

2007 Microelectronics International

doi: 10.1108/13565360810846617

Purpose The purpose of this paper is to compare thick and thin film microstripline response to conducting overlay.Designmethodologyapproach Study changes in transmission and reflection of both thick and thin film microstripline due to overlay of polyaniline PANI thin film on stainless steel and silver. PANI was deposited by electropolymerisation method using HCl and H2SO4.Findings Transmittance of both the thick and thin film microstripline decreases due to the PANI overlay and reflectance increases. Thin film microstripline is more sensitive to the type of conducting overlay than thick film microstripline. PANI deposited on silver is more absorbing than PANI deposited on stainless steel using HCl acid. The overlay makes the response of the microstripline more dispersive.Originalityvalue The increase in reflectance and decrease in transmittance can provide information about the type of overlay materials. There is need for newer materials which can replace traditional metals for microstrip components. PANI might serve this purpose.

Yang, Jianhong; Li, Guifang; Liu, Huilan

2007 Microelectronics International

doi: 10.1108/13565360810846626

Purpose Choosing suitable highK gate dielectrics to reduce the offstate leakage Ioff by edge direct tunneling mechanism, demonstrating that the decreased Ioff increase significantly when the gate dielectrics permittivity are above 25. The purpose of this paper is to report that HfSiON and HfLaO are promising gate dielectrics.Designmethodologyapproach The offstate gate current, drain current, and substrate current are investigated. The IdVgs characteristics for the 50 and 90nm NMOSFET with various gate dielectrics are studied. Edge direct tunneling current IEDT with various gate dielectrics including SiO2, Si3N4 and HfO2 are compared and this paper also examines the IEDT with HfSiON and HfLaO gate dielectrics.Findings IEDT prevails over conventional gateinduced drainleakage current IGIDL, subthreshold leakage current ISUB, bandtoband tunneling current IBTBT and it dominates offstate leakage current. A large increase in offstate leakage current occurs for smaller devices due to increase in IEDT at high Vdd. Although IEDT is decreased with increase in gate dielectrics permittivity K. The authors found fringing induced barrier lowering FIBL which could introduce significant offstate leakage current for K>25. Fortunately, the IEDT with HfSiON and HfLaO gate dielectrics which are twofive orders of magnitude lower than that of SiO2, furthermore, FIBL for HfSiON and HfLaO gate dielectrics are inconspicuous. Moreover, HfLaO and HfSiON have superior electrical performance and thermal stability.Originalityvalue Both edge direct tunneling and FIBL are considered to alternate highK gate dielectrics for nanoscale MOSFET.

Narasimalu, Srikanth

2007 Microelectronics International

doi: 10.1108/13565360810846635

Purpose Ultrafine feature sizes and highperformance requirements have necessitated the integration of lowk dielectrics with siliconlevel interconnects. These are mechanically weaker than previousgeneration materials, a fact that has been recognized to be an industry wide issue. The inherently weaker nature of the lowk dielectric material can pose significant challenges to downstream electronicpackaging processes and materials. The purpose of this paper is to focus on the wire bonding of gold wires on a Culowk pad structure.Designmethodologyapproach The paper presents a numerical model description and simulation procedure.Findings Numerical methods, particularly finite element method based simulations are a good tool to visualize and understand the reasons for success or failure during a bonding process. It enables one to relate the induced stress to the inherent bulk material's strength and interfacial strength. The results from such simulations clearly indicate the highstress locations and the amount of plastic strain that accumulates during the application of compressive force, heat and ultrasonic energy.Originalityvalue These simulations help to understand the device's weaknesses and correlate the failures so as to design the wire bonder equipment with better process control features.

Jharia, Bhavana; Sarkar, S.; Agarwal, R.P.

2007 Microelectronics International

doi: 10.1108/13565360810848156

Purpose The purpose of this paper is to analyze the effects of scaling on the impact ionization and subthreshold current in submicron MOSFETs.Designmethodologyapproach The effects of the various scaling techniques on a 100nm device performances and the dependence of subthreshold current parameters on applied scaling technique are analyzed.Findings The results show that as the channel length is scaled down, multiplication factor increases slowly in the higher regime and rises rapidly in the lower regime of channel length. This result also justifies the inclusion of impactionization effect on subthreshold current. The analysis shows that there is insignificant dependence of multiplication factor on the method of scaling. Similar variations in subthreshold current with channel length scaling have been observed in the analytical results for different scaling techniques.Originalityvalue The paper offers insight into the challenges of MOSFET scaling.

Umarji, Govind; Ketkar, Supriya; Hawaldar, Ranjit; Gosavi, Suresh; Patil, Kashinath; Mulik, Uttam; Amalnerkar, Dinesh

2007 Microelectronics International

doi: 10.1108/13565360810846653

Purpose The purpose of this paper is to ascertain chemical changes occurring at various stages involved in processing of silverbased photoimageable thick films and to determine ensuing topographical features which other wise appeared to be hindered in 2D scanning electron microscopy.Designmethodologyapproach Surface sensitive techniques, viz. Xray photoelectron spectroscopy XPS and atomic force microscopy AFM were used.Findings Interfacial adhesion of silver film with substrate Al2O3 was specifically looked into with respect to role played by photoimaging before and after exposure to ultraviolet light. XPS results revealed occurrence of subtle chemical changes in terms of unsaturation to saturation in CC bonding and also an interesting CAl bonding which presumably improves mechanical adhesion of unfired film with the alumina substrate. AFM was carried out to examine the surface roughness, particle size, and microstructure of film which are very important from the standpoint of highfrequency applications.Originalityvalue Surface sensitive techniques like XPS and AFM were exclusively used in order to characterize silverbased photoimageable thick films.