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Optical, electrical and structural properties of metal oxide thin films of tellurium dioxide (TeO2), indium oxide (In2O3) and silicon monoxide (SiO) and their mixtures were studied in terms of gamma radiation influence. These films were prepared using the thermal vacuum evaporation technique. 60Co and 137Cs sources were used to expose the samples to γ-radiation. It was found that the optical band gap values decreased with increasing radiation dose. The radiation induced changes in the electrical properties of these films. Devices with resistor-type structures and p-n junctions were studied. Irradiation resulted in the degradation of the device performance, e.g. current–voltage characteristics of these devices experienced significant alterations. It was observed that values of current were increased with increasing radiation dose. The response of these devices to radiation was found to be composition-dependent. Radiation-induced changes in the structure and surface morphology of In2O3/SiO films were examined by scanning electron microscopy and X-ray diffraction. The irradiation of these thin films with a dose of 8160 μSv led to a change in their phase from amorphous to partially crystallised.

The positive resist image by dry etching (PRIME) process is a high-resolution positive resist system incorporating deep-UV (DUV)/e- beam exposure, silylation (gas/liquid phase), and dry development. A new method to calculate the silylation profile in the PRIME process is presented. New software modules have been added to the 2-D simulator SLITS (simulation of lithography on topographic substrates) to simulate the silylation and dry-developed profiles in the PRIME process. The si- Iylation and dry-developed profiles for the PRIME process are simulated and compared to experimental results. Simulations were carried out for both e-beam and DUV exposures. Under e-beam exposure, the maxi- mum percentage error between the simulated and experimental results was 137.. Under DUV exposure, the silylation depth at the mask edge can be reduced by increasing the dose thus effectively controlling the resist linewidth. Subject terms: PRIME process; lithography modeling; nanolithography; silylation; dry development.

The resist pattern obtained after a lithography process must reproduce the features on the mask without any kind of distorsion. Best resolution obtained from a particular resist is limited by its contrast. A realistic resist image profile can be predicted using a detailed simulation program like SAMPLE. For characterizing resist image of small features, one has to take into account the abberations like corner rounding etc. This is not possible by the existing programs. Recently a method has been proposed for such an application using a figure of merit (FOM) concept. This approach has been used in this paper to optimize dose in a lithography process by simulation. Three dimensional resist image profile was first computed from a two dimensional image intensity distribution data, for a given rectangular object, by stimulating exposure and development process. Then resist image FOM is calculated from this resist profile. The effect of dose on resist FOM has been studied for different exposure wavelengths and feature sizes. From FOM Vs Dose curves one can get the optimum dose value, corresponding the maximum FOM value.

With the developments in the techniques of artificial intelligence over the last few years, development of advisory, scheduling and similar class of problems has become very convenient using tools such as PROLOG. In this paper an expert system has been described which helps lithographers and process engineers in several ways. The methodology used is to model each work station according to its input, output and control parameters, combine these work stations in a logical sequence based on past experience and work out process schedule for a job. In addition, all the requirements vis-a-vis a particular job parameters are converted into decision rules. One example is the exposure time, develop time for a wafer with different feature sizes would be different. This expert system has been written in Turbo Prolog. By building up a large number of rules, one can tune the program to any facility and use it for as diverse applications as advisory help, trouble shooting etc. Leitner (1) has described an advisory expert system that is being used at National Semiconductor. This system is quite different from the one being reported in the present paper. The approach is quite different for one. There is stress on job flow and process for another.

This paper reports on the development of a flexible nanopatterning approach using the NanoeNablerTM to manufacture miniaturised sensor arrays platform for real-time water quality assessment. Traditionally biosensors are fabricated by lithography, screen printing, inkjet printing, spin-or deep-coating methods to immobilize the sensing element onto substrate pre-patterned with electrodes. NanoeNablerTM patterning method is benchmarked against other currently adapted approaches for cost-effective sensors arrays manufacture. Sensors measuring ~1 µm diameter or more can be patterned for further employment in molecularly imprinted polymer structures. Notably, the dimensions of the sensor depend on the fluid being patterned and on the interaction forces between the substrate and the patterning tool. Thus, careful selecting of patterning parameters is vital for repeatable and controlled manufacture of sensors to guarantee superior sensitivity. The reported nanopatterning method is capable of accurately placing attoliter to femtoliter volumes of liquids, including proteins and DNAs, onto any substrate, thus making it an ideal technology for biomedical sensors. A custom-made 1 cm2 silicon wafer with 48 interdigited electrodes sensor heads was used as a platform for the multi-sensor array with potential use in a wide range of real-time monitoring applications.

PurposeTelemetry capsules have existed since the 1950s and were used to measure temperature, pH or pressure inside the gastrointestinal (GI) tract. It was hoped that these capsules would replace invasive techniques in the diagnosis of function disorders in the GI tract. However, problems such as signal loss and uncertainty of the pills position limited their use in a clinical setting. In this paper, a review of the capabilities of microelectromechanical systems (MEMS) for the fabrication of a wireless pressure sensor microsystem is presented.Design/methodology/approachThe circuit requirements and methods of data transfer are examined. The available fabrication methods for MEMS sensors are also discussed and examples of wireless sensors are given. Finally, the drawbacks of using this technology are examined.FindingsMEMS for use in wireless monitoring of pressure in the GI tract have been investigated. It has been shown that capacitive pressure sensors are particularly suitable for this purpose. Sensors fabricated for wireless continuous monitoring of pressure have been reviewed. Great progress, especially using surface micromachining, has been made in recent years. However, despite these advances, some challenges remain.Originality/valueProvides a review of the capabilities of MEMS.

Thin films of tellurium dioxide (TeO/sub 2/) were investigated for /spl gamma/-radiation dosimetry purposes. Samples were fabricated using thin film vapour deposition technique. Thin films of TeO/sub 2/ were exposed to a /sup 60/Co /spl gamma/-radiation source at a dose rate of 6 Gy/min at room temperature. Absorption spectra for TeO/sub 2/ films were recorded and the values of the optical band gap and energies of the localized states for as-deposited and /spl gamma/-irradiated samples were calculated. It was found that the optical band gap values were decreased as the radiation dose was increased. Samples with electrical contacts having a planar structure showed a linear increase in current values with the increase in radiation dose up to a certain dose level. The observed changes in both the optical and the electrical properties suggest that TeO/sub 2/ thin film may be considered as an effective material for room temperature real time /spl gamma/-radiation dosimetry.

In this work, a PVDF thick film paste was deposited onto interdigitated electrodes to form a capacitor. Two different substrates, alumina and Melinex® were used. Capacitors, fabricated on alumina substrates were tested as strain gauges, and showed a high sensitivity with low hysteresis. Capacitors on Melinex® substrates were tested as pressure sensors by adhering them to planar and cylindrical surfaces and subjecting them to pressures up to 300 kPa. Their sensitivity and hysteresis during cycling were examined and compared. It was found that sensors on cylindrical surfaces showed a higher sensitivity, however the hysteresis was also increased. It is thought that this is due to instabilities in the polymer film, accentuated by stretching of the substrate.

The International Technology Roadmap for Semiconductors (ITRS) identifies the shrinking of lithography critical dimensions (CDs) as one of biggest challenges facing the semiconductor industry as it progresses to smaller geometry nodes. Nanolithography, the patterning of masking CDs below 100nm, enables both nanoscale wafer processing and the exploration of novel nanotechnology applications and devices.Focused Ion Beam (FIB) lithography has significant advantages over alternative nanolithography techniques, particularly when comparing resist sensitivity, topography effects, proximity effects and backscattering. FIB lithography uses the implantation of ions, such as Ga+, in its masking process. Ions implanted into resist in this manner typically have shallow penetration depths (When compared with conventional microelectronic lithography, nanolithography techniques such as EUV, electron beam and nanoimprint lithography require expensive process equipment and the use of non-standard process materials.The 2-step negative resist image by dry etching (2-step NERIME) process is a FIB TSI scheme developed for DNQ/novolak based resists, and involves FIB exposure of resist with Ga+, followed by O2 plasma dry development using reactive ion etching. The 2-step NERIME process uses equipment sets and materials commonly found in microelectronic device fabrication (FIB tool, O2 plasma etcher, DNQ/novolak resists), and provides a low-cost and convenient nanolithography option for proof-of-concept nanoscale processing.To be of practical use, a nanolithography scheme must be capable of patterning nanoscale resist features over substrate topography while retaining resist profile control. The nanolithography scheme must also integrate with subsequent plasma etch processing steps that etch various material films such as metals, Si, SiO2, SiN. The 2-step NERIME FIB TSI process has been used to successfully pattern nanoscale (40nm-90nm) resist features on planar and topography substrates. We have also demonstrated sub-100nm etched features on topography substrates using the 2-step NERIME process, reporting 80nm Polycide and TiN etched features, and 90nm Ti etched features, that exhibit excellent profiles and minimal line edge roughness (LER).It is expected that the 2-step NERIME FIB TSI process will be further extended to etch sub-40nm features over topography substrates. The nanoscale etched features will be used to explore proof-of-concept geometry shrink & novel structures, with many possible applications, including NEMs and nanosensors research and development.

The 2-step negative resist image by dry etching (2-step NERIME) focused ion beam (FIB) top surface imaging (TSI) process is a novel nanolithography technique for creating nanometer scale resist features using conventional DNQ/novolak resists. The 2-step NERIME process combines the advantages of FIB lithography and TSI processing, delivering high aspect ratio nanometer-scale resist critical dimensions (CDs). Previous work has reported 90nm resist CDs over substrate topography using the 2-step NERIME process, and 80nm etched features masked using resist patterned by the 2-step NERIME process. In this work we further extend the 2-step NERIME process, and demonstrate its potential as a low-cost and convenient nanolithography option for proof-of-concept nanoscale fabrication, through the creation of sub-100nm titanium-nitride (TiN) device features.

Present methods for investigation of the GI tract are invasive, distressing for the patient, and give a low diagnostic yield. Wireless, radio telemetry capsules, capable of monitoring physiological changes or visualizing the GI tract are noninvasive and could realize a faster time to diagnoses along with improved treatment of both organic diseases and functional disorders. Consequently, the patient's quality of life would improve. In this paper, early radiotelemetry capsules and the motivating factors for their development are discussed. Following this, prototype and commercially available digestible microsystems making use of microelectronics and microelectromechanical systems are presented. It is shown that these capsules have the potential to combine the functions of their predecessors and furthermore can be used for visualizing the gastrointestinal tract. These systems have the potential to improve diagnostic yield and, in the future, treatment of disease using these capsules should become a reality.

In this work, an investigation of the pressure-sensing properties of a silicone rubber was conducted. Small amounts of carbon black were added to the silicone during fabrication and the effect on the sensitivity was explored. A full investigation of the mechanical and electrical properties of each composition shows that adding carbon black to the material greatly increases its sensitivity to pressure. This increase in sensitivity appears to be related to improvements in the material’s permittivity, which increases with carbon loading.

This paper reports on the gamma radiation-induced changes in thin oxide films deposited by thermal vacuum technique. Structures of various oxides thin films, such as In2O3, SiO and TeO2 and their mixtures in different proportions were studied. The influence of gamma radiation on In2O3/SiO films has resulted in significant changes in the microstructure of this film. Some kind of agglomerations with variable sizes in the range 0.5-3 µm has occurred. After a dose of 8160 µSv an evidence of partial crystallisation was observed with X-ray diffraction. Structural changes in TeO2 thin film were explored by means of Raman spectroscopy. After they have been exposed to g- radiation, a strong peak appeared at 448.83 cm-1, indicating further transformation to g-TeO2 modification.

Thick films of Nickel oxide (NiO) in the form of pn-junctions and planar structures with interdigitated electrodes were investigated for γ-radiation dosimetry purposes. Samples were fabricated using the thick film screen-printing technique. All devices were exposed to a disc-type 137 Cs source with an activity of 370 kBq. They showed an increase in the values of current with the increase in radiation dose up to a certain level. Performance parameters of the devices, such as sensitivity to γ-radiation exposure and working dose region, were found to be highly dependant on the composition of the materials used. Keywords: Nickel Oxide; Thick Films; Gamma Radiation; PN-junction; Interdigitated Electrodes Introduction Accurate dosimetry traceable to national standards underpins the protection of the general public and workers across a wide range of activities including general engineering, radiation processing, nuclear power generation, research and use of radiation in medicine and defence. To meet this demand, considerable research into new sensors is underway, including efforts to enhance the sensors performance through both the materials properties and manufacturing technologies. The development of sensors needs to take advantages of the new performances obtained by controlling the physical and chemical properties of the materials. Metal oxides are widely used in many technological applications, such as coating, catalysis, electrochemistry, optical fibers, sensors, etc [1, 2]. Metal oxide sensors have been utilised for several