Evaluation of closed-vessel microwave digestion method for the determination of trace impurities in polymer-based photoresist by inductively coupled plasma mass spectrometry

A closed microwave digestion method followed by inductively coupled plasma spectrometric (ICP-MS) analysis was evaluated for the determination of trace impurities in photoresist. To optimize the digestion procedure, several digestion parameters such as acid, heating temperature and heating time were evaluated. Besides, the digestion efficiency of used photoresist material and the recovery of analyte elements obtained by the use of gravimetric method and ICP-MS measurement, individually, were also compared to clarify the completeness of digestion. According to our experiments, the gravimetric method was found to be not so relevant to the completeness of digestion, because the remaining sample matrix could cause suppression effect in the subsequent ICP-MS measurement. In view of minimizing blank value and working time, a simple single-step heating program was proposed to mineralize 0.25 ml of photoresist material with 5 ml of nitric acid at 180 °C for 10 min. Based on the comparative study of the analytical results obtained by instrumental neutron activation analysis (INAA) and proposed method, the reliability of proposed method for the determination of trace metallic impurities in photoresist material has been confirmed.     

Quantum chemical modeling for 157 nm photolithography

In its continuing quest for smaller length scales, the electronics industry plans to introduce 157 nm as the next lithographic wavelength. Accordingly, there is a pressing need to develop photoresists that are more transparent, and pellicles that are both more transparent and more durable. With the advent and popularization of time-dependent density functional theory (TD-DFT), we now have a practical quantum chemical method for calculating excitation energies and transition moments in the vacuum ultraviolet (VUV) which can greatly assist in the scouting of highly transparent materials. We have performed TD-DFT calculations for a broad variety of fluorinated molecules and we will report calculated VUV photoabsorption spectra for a large family of model fluorohexanes. These calculations, which span a range from 1-fluorohexane to CH₃CF₂CF₂CF₂CF₂CH₃, illustrate some of the principles one may use to design low absorption polymeric materials.     

Fabrication of SU-8 based microchip electrophoresis with integrated electrochemical detection for neurotransmitters

A new SU-8 based microchip capillary electrophoresis (MCE) device has been developed for the first time with integrated electrochemical detection. Embedded electrophoretic microchannels have been fabricated with a multilayer technology based on bonding and releasing steps of stacked SU-8 films. This technology has allowed the monolithic integration in the device of the electrochemical detection system based on platinum electrodes. The fabrication of the chips presented in this work is totally compatible with reel-to-reel techniques, which guarantee a low cost and high reliability production. The influence of relevant experimental variables, such as the separation voltage and detection potential, has been studied on the SU-8 microchip with an attractive analytical performance. Thus, the effective electrical isolation of the end-channel amperometric detector has been also demonstrated. The good performance of the SU-8 device has been proven for separation and detection of the neurotransmitters, dopamine (DA) and epinephrine (EP). High efficiency (30,000-80,000 N/m), excellent precision, good detection limit (450 nM) and resolution (0.90-1.30) has been achieved on the SU-8 microchip. These SU-8 devices have shown a better performance than commercial Topas (thermoplastic olefin polymer of amorphous structure) microchips. The low cost and versatile SU-8 microchip with integrated platinum film electrochemical detector holds great promise for high-volume production of disposable microfluidic analytical devices.     

Stripping of photoresist on silicon wafer by CO(2) supercritical fluid

Supercritical CO₂-based fluid is not only being considered as environmentally benign medium for photoresist (PR) removal in electronic device manufacture, but also capable of challenging feature dimensions. Despite many attractive properties, clear supercritical CO₂ has little solvating power for PR. Here, two acetate modifiers were selective to add in the CO₂ and evaluated individual contribution to the overall stripping rate by factorial experiment design, which included four other factors with four level ranges for each one and concluded the best 90% extraction efficiency would be obtained under the optimized parameters: 2.5 min static time, 35 min dynamic time, 1.25 ml ethylacetate spiked, 125 °C oven temperature and 480 atm CO₂ pressure. As analyzing the variances of these contributors to this system, it disclosed that dynamics controlled the stripping mechanism before near 35 min purging but thermodynamics took over after then; and that increasing pressure was more competent for removing PR than increasing temperature. All supercritical extracts were from two commercial PR coated on two substrates and analyzed by UV absorption spectrometry. Removing PR coated on silicon oxide layer was easier than that on Al-Cu alloy one.     

氩离子激光固化环氧树脂制作三维微结构

利用激光束进行三维成像是通过逐层光引发聚合形成宏观尺度的三维实体 .最近出现的激光全息光刻技术是利用激光束的干涉产生三维全息图案 ,让感光树脂在全息图案中曝光 ,从而一次形成三维周期有序微结构 .通过调节激光干涉及波长可控制三维结构的形状及尺寸 .利用该技术获得亚微米尺度上周期性重复的三维微结构 ,可用于制作三维光子晶体 [1,2 ]等具有独特性能的聚合物材料 .本文用铁芳烃化合物与特种环氧树脂配制成阳离子型可见光固化树脂 ,在氩离子激光器产生的多束可见连续激光相干形成的空间干涉光场中曝光 ,成功地制备出亚微米量级的三…     

High-power laser interference lithography process on photoresist: Effect of laser fluence and polarisation

High throughput and low cost fabrication techniques in the sub-micrometer scale are attractive for the industry. Laser interference lithography (LIL) is a promising technique that can produce one, two and three-dimensional periodical patterns over large areas. In this work, two- and four-beam laser interference lithography systems are implemented to produce respectively one- and two-dimensional periodical patterns. A high-power single pulse of ∼8 ns is used as exposure process. The optimum exposure dose for a good feature patterning in a 600 nm layer of AZ-1505 photoresist deposited on silicon wafers is studied. The best aspect ratio is found for a laser fluence of 20 mJ/cm². A method to control the width of the sub-micrometer structures based on controlling the resist thickness and the laser fluence is proposed.     

SYNTHESIS AND THERMAL PROPERTIES OF A NEW CHOLIC ACIDCONTAINING COPOLYMER

A new copolymer was synthesized by free radical polymerization in solution from methyl 3α-methylacryloyl-7α, 12α-dihydroxy-5β-cholan-24-oate (MACAME) and maleic anhydride (MAN). The copolymer was characterized by FT-IR and functional group analysis. The reactivity ratios of the two monomers were estimated [r_1 = 11.6 (MACAME), r_2 = 0.01(MAN)] by conducting a series of copolymerizations with a variety of monomer feed compositions and analyzing thecopolymer composition. Thermogravimetric and differential scanning calorimetric analyses of the samples indicate that thecopolymer possesses good thermal stability. The temperature at which the copolymer samples experienced a 10% weight loss(T_(WL)) is over 287℃, and the T_g ranged from 174 to 185℃ for the copolymers.     

Photoactive liquid polysulfides: preparation, characterisation, photocuring and potential applications

Photoactive terminal groups X have been introduced into liquid polysulfides to give X(SCH₂CH₂OCH₂OCH₂CH₂S)_nX where X=acetyl, acryloyl, cinnamoyl, benzoyl, I-naphthaloyl, oxalyl, p-toluene sulfonyl, terephthaloyl, 1,3,5-benzene tricarbonyl and methylvinylsilyl. The resulting modified LPs have been characterised by IR, UV, ¹NMR spectroscopy, size exclusion chromatography and ESI and FAB mass spectrometry. The results of photoirradiating these materials were examined and some selected for further study with regard to their potential application as coatings, adhesives and photoresists, both as such and as components of formulations. While the slowness of cure of the modified LPs presents a difficulty, they function satisfactorily as components of established photocurable compositions, conferring advantages in a number of cases (scratch resistance, speed of cure, hardness).     

Novel vinyl ether functionalized fluorene polymers for active incorporation into common photoresist matrices

A novel vinyl ether functionalized fluorene monomer was prepared to produce a series of fluorene-based polymers with different emitter units to cover emission in the visible spectrum whilst retaining the same main absorption profile. The vinyl ether functionality allows for active incorporation of the light emitting polymers into standard vinyl ether and glycidyl ether photoresist materials. This enables photopatterning of light emitting structures for application in UV down-conversion, waveguiding and for lasing media.     

AZ-1518 Photoresist analysis with synchrotron radiation using high-resolution time-of-flight mass spectrometry

With the aim of identifying molecular modifications among photoresists unexposed and previously exposed to the ultraviolet light the photon stimulated ion desorption (PSID) technique was employed in the study of the AZ-1518 photoresist. Data acquisition was performed at the Brazilian Synchrotron Light Source (LNLS), during a single-bunch operation mode of the storage ring and using high-resolution time-of-flight mass spectrometry (TOF-MS) for ion analysis. PSID mass spectra on both photoresists (unexposed and exposed) were obtained following the S K-shell photoexcitation and desorption ion yield curves have been determined for the main fragments as a function of the photon energy. The AZ-1518 photoresists presented different PSID spectra, showing characteristic fragments. Most of the analyzed ions showed larger relative yields for the exposed photoresist. Fragments related to the photochemical decomposition of the photoresist could be clearly identified. These results showed that the PSID technique is adequate to investigate structural changes in molecular level in unexposed and exposed photoresists.