Impact of molecular structure of polymer in 193 nm resist performance

Miniaturization in microelectronic technologies requests a development of new high-performance materials for microlithography with good resolution of the critical dimension. However, the real impact of polymer structure on lithographic performances is not yet well understood to predict the properties of formulated resist. Our approach is the synthesis and characterization of model resists and the understanding of the relationship between material – properties – processes. In this work we present the influence of the polymer’s molecular weight in lithographic profile of the generated patterns. The limits of the polymer’s molecular weight values based on model terpolymers, consisting of methacrylate matrix, for efficient patterning have been identified. Finally, the ineffective sensitivity and dissolution issue of the polymer resists having an average molecular weight of 30 kg/mol was extensively examined and attributed to the molecular weight of the polymer and more precisely to the radius of gyration of the polymer.     

Electrochemical polymerizatıon of hexachloroethane to form poly(hydridocarbyne): a pre-ceramic polymer for diamond production

Due to its structural similarity with diamond, poly(hydridocarbyne) (PHC), which is sp³-hybridized, is a unique polymer that can be easily converted to diamond and diamond-like-carbon ceramics upon heating. PHC can be easily synthesized via the electrochemical polymerization of chloroform as previously reported. Here, we report the electrosynthesis of PHC from hexachloroethane. Since hexachloroethane has six chlorine atoms in its structure, polymerization takes place through the carbons simultaneously. Thus, the polymer is bigger in chain length than PHC obtained from the polymerization of chloroform. UV-vis, FTIR, and NMR spectroscopy were utilized to determine the polymer structure. Conversion of the polymer to diamond was accomplished by heating at 1000 °C under a nitrogen atmosphere as confirmed by Optical Microscopy and Raman analysis. XRD studies showed that the product is an assortment of diamond forms.     

Network formation in nitroxide-mediated radical copolymerization of styrene and divinylbenzene in miniemulsion: Effect of macroinitiator hydrophilicity

Nitroxide-mediated crosslinking radical copolymerizations of styrene and divinylbenzene have been carried out in aqueous miniemulsion with Dowfax 8390 as surfactant at 125 °C employing TEMPO-based macroinitiators of various hydrophilicities (random copolymers comprising styrene and methyl acrylate). The pendant conversion (i.e. the degree of crosslinking) increased with increasing macroinitiator hydrophilicity and with decreasing particle size. It is proposed that a concentration gradient is generated within the particle such that the macroinitiator concentration tends to be higher near the oil-water interface than in the particle interior. The macroinitiators are surface active and are thus preferentially adsorbed at/located near the oil-water interface. This in turn leads to an increase in the ratio [pendant unsaturation]/[monomer] in the vicinity of propagating radicals, which are generated from the macroinitiators, and thus an increase in pendant conversion. This effect is enhanced by an increase in macroinitiator hydrophilicity and a decrease in particle size. The present approach offers novel means of controlling network formation in dispersed systems.     

Monitoring of laser processing using induced current under applied electric field on laser produced-plasma

A new electrode circuit for measuring the induced current from laser plasma produced during laser material processing has been devised. The new electrode circuit has greatly increased the possible separation between the electrodes and the workable probing distance of the electrodes from the processed sample surface, namely 38 and 22 mm, respectively, sufficing the requirements of actual industrial laser material processing, avoiding direct contact of the electrodes with the big plasmas and profound sputtering. Several possible electrode configurations were investigated to accommodate the specific needs of the actual laser processing. It was shown that this technique is a very effective tool for accurately determining the moment of completion of penetration, as required in the laser piercing process. In contrast to this, the optical method currently in use cannot accurately determine the piercing completion moment due mainly to the disturbance from smoke arising at the processing point. A preliminary work using a CW CO₂ laser normally used in the actual industrial material processing was also made, resulting in a strong induced current signal corresponding to the laser pulse duration and frequency. The signal was successfully used for monitoring the penetration completion in a stainless steel plate drilling process. This reveals that this technique can be used for monitoring actual industrial material processing using high power lasers.     

Molecularly imprinted hydrogels for fibrinogen recognition

Molecularly imprinted hydrogels (MIHs) composed of N-isopropylacrylamide (NIPA) and maleic acid (MA) monomers and fibrinogen (Fbg, MW: 340 kDa, pI: 5.8) imprinted molecule were fabricated in pH buffer solutions (pH_prep: 4.0, 5.8 and 8.0). The non-imprinted hydrogels were also prepared in the same conditions without Fbg imprinted molecule. The adsorption equilibrium constant and the maximum adsorption capacity of the MIH prepared in pH 4.0 were evaluated to 9.61 mL mg^?1 and 38.99 mg protein g^?1 dry gel in pH 4.0 buffer solution, respectively. The selectivity tests were also performed by using two reference molecules as bovine serum albumin (BSA, MW: 67 kDa, pI: 4.78) and urease (MW: 480 kDa, pI: 5.99). The MIHs have 2.37–4.23 times higher selectivity for the Fbg imprinted molecule than the non-imprinted hydrogels prepared in the same conditions. Easy preparation of the MIHs, their high stability and ability to recognize small and large proteins, as well as to discriminate molecules with small variations in charge, make this approach attractive and broadly applicable in biotechnology, assays and sensors.     

Zero-Index Metamaterial Superstrates UWB Antenna for Microwave ImagingDetection

Metamaterials (MTM) can enhance the properties of microwaves and also exceed some limitations of devices used in technical practice. Note that the antenna is the element for realizing a microwave imaging (MWI) system since it is where signal transmission and absorption occur. Ultra-Wideband (UWB) antenna superstrates with MTM elements to ensure the signal transmitted from the antenna reaches the tumor and is absorbed by the same antenna. The lack of conventional head imaging techniques, for instance, Magnetic Resonance Imaging (MRI) and Computerized Tomography (CT)-scan, has been demonstrated in the paper focusing on the point of failure of these techniques for prompt diagnosis and portable systems. Furthermore, the importance of MWI has been addressed elaborately to portray its effectiveness and aptness for a primary tumor diagnosis. Other than that, MTM element designs have been discussed thoroughly based on their performances towards the contributions to the better image resolution of MWI with detailed reasonings. This paper proposes the novel design of a Zeroindex Split Ring Resonator (SRR) MTM element superstrate with a UWB antenna implemented in MWI systems for detecting tumor. The novel design of the MTM enables the realization of a high gain of a superstrate UWB antenna with the highest gain of 5.70 dB. Besides that, the MTM imitates the conduct of the zeroreflection phase on the resonance frequency, which does not exist. An antenna with an MTM unit is of a 7 × 4 and 10 × 5 Zero-index SRR MTM element that acts as a superstrate plane to the antenna. Apart from that, Rogers (RT5880) substrate material is employed to fabricate the designed MTM unit cell, with the following characteristics: 0.51 mm thickness, the loss tangent of 0.02, as well as the relative permittivity of 2.2, with Computer Simulation Technology (CST) performing the simulation and design. Both MTM unit cells of 7 × 4 and 10 × 5 attained 0° with respect to the reflection phase at the 2.70 GHz frequency band. The first design, MTM Antenna Design 1, consists of a 7 × 4 MTM unit cell that observed a rise of 5.70 dB with a return loss (S11) −20.007dB at 2.70 GHz frequency. The second design, MTM Antenna Design 2, consists of 10 × 5 MTM unit cells that recorded a gain of 5.66 dB, having the return loss (S11) −19.734 dB at 2.70 GHz frequency. Comparing these two MTM elements superstrates with the antenna, one can notice that the 7 × 4 MTM element shape has a low number of the unit cell with high gain and is a better choice than the 10 × 5 MTM element in realizing MTM element superstrates antenna for MWI.