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The carbonization of various types of metal–organic frameworks (MOFs) was carried out under N2 gas flow and high temperature. The formation of carbonized MOFs (CMOFs) was monitored by Raman spectroscopy. In addition to the well-known D and G bands in Raman spectra, the salient G′ band feature was observed only in Mn-, Fe-, Co-, and Ni-containing CMOFs. On the other hand, CMOFs containing other metals (Al, Cr, V, Cu, and Zr) do not show the G′ band. Furthermore, the G′ band was also observed when we mixed the nitrate salts of Mn(II), Fe(III), and Co(II) with Al-containing MOFs using the same treatment conditions as in the formation of CMOFs. The G′ band is known to be related to the stacking order of graphitic layers. The presence of the Raman G′ band in CMOFs can be ascribed to the catalytic activity of Mn, Fe, Co, and Ni. The trend of the G′ band to G band intensity ratio resembles the “volcano curve” in the description of the behavior of catalytic activities of transition metals. The G′ bands in Mn-, Fe...

The radio-frequency discharge of xylene isomers was monitored with optical emission spectroscopy (OES). It was found that the meta isomer showed relatively stronger excimer to monomer intensity ratio than the other two isomers. OES also indicates the formation of xylyl (methylbenzyl) radicals. The reaction products of low pressure xylene plasmas were analyzed by gas-chromatography mass spectrometry (GC/MS). It showed that the main composition of the reaction products was 1,2-di-p-tolylethane (DPTE), regardless the types of xylene isomers used. It is known that o- and m-xylyl radicals can undergo rearrangement and convert to p-xylyl radicals. Similar to the cases in benzene and toluene plasmas, the recombination reaction between two p-xylyl radicals is believed to be responsible for the formation of DPTE. Density functional theory calculations suggest that the direct conversion of xylene excimers to DPTE is unlikely.

Under inert gas flow and high temperature, carbonization of aluminum-based metal–organic frameworks (MOFs) was carried out. The formation rate of carbonized MOFs (CMOFs) was monitored by the variation of the Raman D band to G band intensity ratio with heat treatment duration. Powder x-ray diffraction (PXRD) and scanning electron microscope (SEM) techniques were used to confirm the formation of CMOFs. The activation energy was extracted from the temperature-dependent rate constants using the Arrhenius equation and correlated with the structural properties of precursor MOFs such as pore size and the number of carbon atoms per ligand. A reaction mechanism is proposed and discussed for the formation of CMOFs based on Raman observation. Copyright © 2016 John Wiley & Sons, Ltd.

Aluminum oxide (Al 2 O 3 ) and chromium oxide (Cr 2 O 3 ) nanoparticles were synthesized by thermolysis of metal-organic frameworks (MOFs). Further O 2 plasma treatment is required to obtain high crystalline quality metal oxides. The composition and morphology of metal oxide nanoparticles were confirmed by powder X-ray diffraction and scanning electron microscopy characterization, respectively. The quality of synthesized metal oxides was also examined by observing the surface-enhanced Raman scattering (SERS) spectra of methyl orange adsorbed on Al 2 O 3 and Cr 2 O 3 . The observed SERS effect can be ascribed to charge-transfer (CT) resonance effect between methyl orange and metal oxide surfaces. UV–vis absorption spectra and DFT calculations of metal oxide- methyl orange complexes have confirmed that the observed SRS effect is due to CT resonance between the metal oxide nanoparticles and the adsorbed methyl orange molecules.

The adsorption of methyl red (MR) isomers (ortho, meta, and para) on metal-organic frameworks (MOFs) was investigated by using a fluorescence quenching technique. All three MR isomers were found to quench the fluorescence of MOFs effectively. Nonlinear fluorescence quenching trends were observed in Stern-Volmer plots. A modified nonlinear Stern-Volmer equation with the concepts of multiple adsorption sites, adsorption strength, and quencher accessibility was successfully adopted to fit the fluorescence quenching data. The fitted parameters were correlated with the structural properties of MRs and MOFs. The order of quenching efficiency was found to be m-MRp-MRo-MR for all MOFs. This indicates that MR molecules not only adsorb via carboxylate-metal bonding but also adsorb through π-π interactions between the aromatic rings of MR and linker molecules in MOFs. The position of the carboxylate group in MRs and the structure of the linkers in MOFs are the key factors affecting the fluorescence quenching efficiency.

Plasma treatment effect on Ag colloids was investigated using X-ray photoelectron spectroscopy (XPS) and surface-enhanced Raman scattering (SERS) techniques. XPS showed that O 2 plasma was critical in removing organic residues in Ag colloids synthesized using citric acid as a reducing agent. With O 2 plasma treatment, Ag colloids were also oxidized to form flower-like Ag 2 O nanostructures. The formation mechanism is proposed. The SERS spectral intensity of methyl orange (MO) adsorbed on Ag surface became deteriorated with O 2 plasma treatment. Followed by H 2 plasma treatment, the SERS intensity of MO on Ag regained, which indicated that Ag 2 O has been reduced to Ag. Nonetheless, the reduction by H 2 plasma could not bring Ag back to the original as-synthesized nanoparticle morphology. The flower-like nanostructure morphology still remained. The photocatalytic degradation reactions of methylene blue (MB) aqueous solutions were carried out using Ag colloids and Ag 2 O nanostructures. The results show that Ag 2 O is more efficient than Ag colloids and many other metal oxides for the photocatalytic degradation of MB in solution when utilizing visible light.

4-mercaptobenzoic acid (4-MBA) adsorbed on Ag colloids has been investigated by surface-enhanced Raman scattering (SERS) spectroscopy. From the intensity variation of the symmetric stretching COO− vibration band corresponding to different pH values, it shows that 4-MBA molecules are bonded to the Ag surface only through the S atoms at acidic conditions, but through the S atoms and the COO− groups at neutral or alkaline conditions. The 4-MBA bonding to Ag shows SERS activity with multilayer adsorption (Freundlich isotherm model). Raman spectra calculated by density functional theory (DFT) with emphasis on long-range charge-transfer effect were compared with experimental observation to interpret the adsorption behavior of 4-MBA on the Ag surface. From both DFT simulations and experimental observation, we have verified that the contribution of electromagnetic and chemical enhancements in the SERS spectra of 4-MBA adsorbed on Ag are equally important.

Surface-enhanced Raman scattering (SERS) spectra of azo dyes (methyl orange and p-methyl red) adsorbed on ZnO nanoparticles were observed. Hydrothermally synthesized ZnO nanoparticles were characterized by powder X-ray diffraction and X-ray photoelectron spectroscopy. The ZnO nanoparticle size, monitored with X-ray diffraction, was tuned by calcination to optimize SERS intensities. The observed SERS effect of azo dyes adsorbed on ZnO can be ascribed to charge-transfer resonance effect. Time-dependent density functional theory was used to calculate the optical spectra and interpret the chemical enhancement observed in the experiment. The SERS enhancement factors for methyl red on ZnO were boosted by nearly four times and twice with O2 plasma and H2 plasma, respectively. However, plasma treatment showed no effect on the enhancement factors of methyl orange on ZnO. We conclude that plasma-induced defect formation and band gap shift in ZnO and the coupling of energy levels between ZnO and azo dye molecules are responsible for the observed enhancement of SERS intensities. Copyright © 2014 John Wiley & Sons, Ltd.

Hydrothermally synthesized ZnO nanorods were treated with hydrogen and oxygen plasmas. We have found that the photoluminescence (PL) intensity of ZnO nanorods increases with hydrogen plasma treatment, but decreases after the subsequent treatment of oxygen plasma. There is no significant increase of PL intensity only by oxygen plasma treatment. By analyzing the components of the deep level emission band, we have concluded the plasma-induced PL intensity variation and band position shift are related to the existence of intrinsic defects in ZnO nanorods. H2 plasma reduces the concentration of oxygen vacancy or singly ionized oxygen vacancy, whereas O2 plasma increases the concentration of interstitial oxygen. The PL result is compared with surface-enhanced Raman scattering (SERS), X-ray power diffraction and scanning electron microscope characterization. We believe that plasma-induced defect formation in ZnO is also the reason responsible for the observed SERS intensity enhancement.

We report the direct observation of surface-enhanced Raman scattering (SERS) effect using metal–organic frameworks (MOFs) as substrates. Without the aid of any metal colloids or enhancing agents, the SERS signals of methyl orange (MO) adsorbed in MOFs were observed and even remained active if the organic linkers in MOFs were completely removed by high temperature and O2 plasma treatments. It implies that the SERS active site is at the metal oxide clusters. The ultraviolet-visible spectra of MO, MOFs, and MO–MOF complexes show that absorption peaks are far from laser excitation line. Thus, conventional resonance enhancement effect should be ruled out, and charge-transfer mechanism is the most likely scenario responsible for the observed SERS effect. Density functional theory (DFT) was used to interpret the chemical enhancement mechanism and the adsorption orientation-dependent SERS spectra in our observation. The preferred adsorption orientations calculated by DFT method are consistent with the observed SERS results. Copyright © 2013 John Wiley & Sons, Ltd.

The degradation of aqueous solutions containing azo dyes (ortho-, meta-, and para-methyl red) was carried out by means of atmospheric pressure plasma treatment. As evidenced by optical emission spectroscopy, the metastable argon in the discharge is responsible for initiating reactions in dye solutions. The bleaching of aqueous solutions is attributed to the destruction of dye molecules as observed in the UV–visible absorption spectra. We found that the degradation pathways of methyl red critically depend on the pH values in aqueous solutions as well as isomeric structures. The reaction pathways are entirely different in basic (pH = 11), near-neutral (pH = 6), and acidic conditions (pH = 2). Kinetic analysis shows that acidic condition gives the fastest degradation rates of methyl red isomers with removal rate: ortho > meta > para among all conditions. At basic condition, the degradation rates are equally slow for all methyl red isomers.

Various kinds of plasma chemistries were used in the study of polysilicon gate stack etch. Different degrees of gate oxide surface roughness were observed. Stable gate oxide thickness and smooth surface were found when using fluorine-based plasma chemistries. In contrast, non-fluorine-based chemistry tends to give uneven gate oxide thickness and rough surface. The stability of the gate oxide thickness can be controlled by chamber seasoning when using non-fluorine-based chemistry. It is also noticed that fluorine-based chemistries always result in thicker remaining gate oxide than the one without fluorine. The type of wafer used for seasoning can also have influence on chamber condition and subsequently the etch rates and gate oxide thickness. From the trends of emission intensity of Si, it is believed that etch byproducts as well as chamber wall polymer have potential impacts on the observed variation of gate oxide surface roughness, thickness, and etch rates.

We report an approach to the reversible tuning of the band gaps of metal oxide (MO) films. ZnO and CuO, synthesized by hydrothermal methods, were treated with hydrogen and oxygen plasmas. From UV–visible transmittance spectra, we have found that the optical band gaps of MO films blue-shifted with hydrogen plasma treatment, but red-shifted with oxygen plasma treatment. By alternating the treatment sequences of hydrogen and oxygen plasmas, the MO optical band gap values can be reversibly fine-tuned with the tunable ranges of 80 and 550 meV for ZnO and CuO, respectively. The mechanism for reversible tuning of optical band gaps is proposed based on the results of optical emission, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy characterization. Compared to conventional metal ion doping and high temperature annealing methods, the use of room temperature hydrogen and oxygen plasmas for tuning band gaps is more environmentally friendly.

We report the study of surface-enhanced Raman scattering (SERS) and photocatalytic reactions of methylene blue (MB) adsorbed on cubic silver oxide (c-Ag2O) nanocrystals. The SERS activities of MB observed on c-Ag2O are surface coverage-dependent. According to the SERS selection rules, the strong intensities of the C–S–C and C–N–C bending modes imply that the MB molecules are adsorbed on the c-Ag2O surface with a near-perpendicular position. On the other hand, if these modes are weak, MB assumes a near-parallel position to the c-Ag2O surface. Under the “perpendicular” condition, the photocatalytic reaction rate of MB observed on c-Ag2O surfaces is first order at a high surface coverage, whereas under the “parallel” condition, the observed rate is zero order at a low surface coverage. The SERS intensity trends and the kinetic behavior of MB on c-Ag2O are correlated.

Multiwalled carbon nanotubes (MWCNTs) were treated with a low-pressure water plasma, and the formation of defects on the MWCNT surface was monitored via the changes in the Raman D band to G band intensity ratio that occurred with different plasma treatment times and different temperatures. A kinetic model with two competing processes (defect formation and defect scavenging) was adopted to interpret the observed nonlinear time-dependent intensity ratio trends. The fitted activation energy (Ea) for the defect formation process was found to be higher than that of the defect scavenging process. This was ascribed to the fact that the OH radicals were more effective in reacting with carbon defects and impurities than with pure CNTs. The Raman-determined Ea’s were also found to be excitation energy-dependent, with maximum values for red light. Such a unique dependence is characteristic of highly π-conjugated carbon systems.

Supported gold nanoparticles have been proven to be active in the hydrogenation of the acetylene. In this work, we applied gold nanoparticles supported on silica for the selective hydrogenation of acetylene in excess ethylene that was close to current industrial practices. Amine group surface-functionalized silica was used to absorb the gold precursor AuCl 4 - , and small size-controlled gold nanoparticles are formed after chemical reduction. For the first time, O2 plasma was employed to remove the APTES grafted on the surface of silica for preparing the highly dispersed gold nanoparticles (∼3 nm). The results of IR, TGA, XRD, and TEM showed that O2 plasma working under mild conditions (room temperature and low pressure) can efficiently remove the organic compounds without causing the aggregation of the gold nanoparticles. The plasma-treated catalyst Au/SiO2 gave excellent low-temperature selective catalytic activity in the hydrogenation of acetylene. The effects of the reduction temperatures on the catalytic performances of the Au/SiO2 were investigated. The enhanced performance of gold nanoparticles supported on silica as pretreated by O2 plasma was ascribed to two effects: (1) the small size of the gold nanoparticles supported on silica, (2) the nearly neutral charge on the Au nanoparticle, which is favorable to the activation of hydrogen.

Chemical oxidation of multiwalled carbon nanotubes (MWCNTs) using H 2 SO 4 /HNO 3 solution has been monitored by micro-Raman spectroscopy and X-ray absorption spectroscopy. The diameter distribution variation in MWCNTs due to chemical oxidation has been measured by scanning electron microscopy and transmission electron microscopy. The Raman dispersion behaviors of the intensity ratio and the band positions of the D, G, and G′ bands were found to be correlated with the MWCNT diameter distribution. It was also found that, during the nanotube unzipping process, defect formation complicates the observation of the diameter-dependent Raman dispersion effect. The curvature effect plays an important role in the intensity ratio trend. On the other hand, defect formation dominates the band position trend.

We have adopted different fitting procedures to study the Raman dispersion behavior of the G' band in plasma-treated multi-walled carbon nanotubes (MWCNTs). Our analysis shows that the trend of the G' band dispersion is related to the presence of defects in the MWCNTs. The intensity ratio dispersions involving the G' 21 , G' 32 , G' 41 , and G' 42 components of the G band behave in a similar way to the well known D to G band ratio (D/G), which is a good criterion for estimating the defect content in MWCNTs. The G' 21 , G' 32 , G' 41 , and G' 42 peaks are shown to belong to the lower-frequency components of the G' band by using two-, three-, and four-peak fitting procedures. Conversely, the higher-frequency components G' 22 , G' 33 , G' 43 , and G' 44 behave like the Gband and are related to the non-defect content. Consequently, the intensity ratios G' 21 /G' 22 ; G' 32 /G' 33 , and G' 41+42 /G' 43+44 show the same dispersion behavior as that of D/G. The difference of band position between the high and low frequency G' band components is found to be sensitive to plasma treatment.

We report the experimental study of prevention of charge induced corrosion of tungsten vias after metal etch using wet chemical solutions and silicon oxynitride (SiON) shielding film. It was found that one of the solutions could effectively prevent corrosion of tungsten vias and leave essentially no polymer residue on metal lines. The performance of other solutions is poor due to the formation of polymer residues or sidewall erosion on metal lines. We have demonstrated that the combination of wet chemical treatment with SiON as the dielectric charge shielding film was as effective as other standard methods for preventing corrosion of tungsten vias. It was also found that SiON has strong impacts on chamber wall conditions and metal line profile.

In this study, a series of poly(divinylbenzene-alkyl methacrylate) monolithic stationary phases, which were prepared by single step in situ polymerization of divinylbenzene and various alkyl methacrylates (butyl-, octyl-, or lauryl-methacrylate), were developed as separation columns of benzophenone compounds for capillary electrochromatography (CEC). In addition to the presence of plenty of benzene moieties, the stationary phases contained long and flexible alkyl groups on the surface. With an increase in the molecular length of alkyl methacrylate, the polymeric monolith, which had higher hydrophobicity, effectively reduced the peak tailing of benzophenones, but a weaker retention was observed. The unusual phenomenon was likely due to the π–π interaction between the aromatic compound and the polymeric material. The usage of longer alkyl methacrylate as reaction monomer limited the retention of aromatic compounds on the stationary phase surface, thus the π–π interaction between them was possibly reduced. Consequently, the retention time of aromatic compounds was markedly decreased with an increase in carbon length of alkyl methacrylate that was carried on the polymeric monolith. Compared to previous reports on polystyrene-based columns in which the peak-tailing problem was reduced by decreasing the benzene moieties on the stationary phase, this study demonstrated that the undesirable retention (peak-tailing) could also be improved by the inclusion of long alkyl methacrylate to the polystyrene-based columns.

Metal-organic frameworks (MOFs) containing Fe, Cr, Ni, and Cu were calcined under nitrogen flow. The formation of carbonized MOFs (CMOFs) was monitored by electrical conductivity, powder X-ray diffraction, and Raman spectroscopic techniques. To remove metallic residues in CMOFs, HF treatment was performed. Powder X-ray diffraction analysis showed that only Ni, but not Fe, Cr and Cu, could be completely removed from CMOFs after HF treatment. Raman spectroscopic data indicated that well-stacked graphene layers structures were present only in Fe and Ni-containing CMOFs. The electrical conductivity, powder X-ray diffraction, and Raman data were correlated. The effect of acid treatment on the structure of CMOFs and the performance of CMOFs as electrode materials were evaluated.

Plasma treatment of multi-walled carbon nanotubes (MWCNTs) using an atmospheric pressure hydroxyl radical (OH) source has been monitored with micro-Raman spectroscopy. We use dispersion behavior of the intensity ratio, band position, and linewidth of the D, G, D′, and G′ bands to probe the defect formation and oxidation process in MWCNTs. A simple kinetic model is adopted to interpret the observed dispersion trends in plasma-treated MWCNTs. X-ray photoelectron spectroscopic analysis, scanning electron microscopy inspection, and Raman dispersion characterization of MWCNT surfaces suggest that the dominant effect of OH plasma on MWCNTs is reduced π-conjugated states due to creating structural defects and attachment of oxygen-containing functional groups.

In this study, a series of novel polymeric monolithic columns prepared by single-step in situ copolymerization of 1-octadecene (OD), divinylbenzene (DVB) and/or styrene (S), were developed as separation columns for the sulfonamide analyses. On the CEC method, the composition of monomer mixtures (i.e. the ratio of S versus OD), content of charge-bearing monomer (vinylbenzyl trimethylammonium chloride) and volume fraction ratio of ACN in the mobile phase, was found to be the predominant influences for sulfonamide separation. Furthermore, an online sample concentration step, field-amplified sample injection, was used to enhance the detection sensitivity of sulfonamides. Sample matrix's pH had a significant effect on the sulfonamide sensitivity. For the eight sulfonamides, the proposed poly(DVB-OD) monolithic stationary phase coupled with field-amplified sample injection step could achieve a reproducible baseline separation within 15 min and LODs in the range of 8.1-28.2 microg/L.

Multiwalled carbon nanotubes (MWCNTs) were treated with an atmospheric pressure plasma source using an argon/water mixture. Optical emission diagnostics has shown that hydroxyl radicals (OH) were the major reactive species in the plasma. The structural changes in MWCNTs were monitored by micro-Raman spectroscopy. The observed variation of the D and G band intensity ratio and position dispersion with plasma treatment time was ascribed to the change in structural disorder on MWCNT surfaces. Scanning electron microscopic study showed that some defects can be induced in MWCNTs during plasma treatment. Results of thermogravimetric analysis indicated that atmospheric pressure OH plasma is as effective as traditional wet methods for purifying MWCNTs.

In this study, an on-line concentration method, ASEI (anion-selective exhaustive injection)-sweeping technology which was coupled with microemulsion EKC (MEEKC), was used to analyze and detect six catechins ((-)-epicatechin, (+)-catechin, (-)-epigallocatechin gallate, (-)-epicatechin gallate, (-)-epigallocatechin, and (-)-gallocatechin). In addition to the effects of the buffer pH and electrolyte concentration on stacking, the compositions of microemulsion (types of oil phase, and types and levels of cosurfactant) also dominated the stacking effect of catechins. In MEEKC, the effect of the type of oil in microemulsion on separation mechanism is often unclear. This study had demonstrated that the oil type in microemulsion indeed altered the affinity of oil droplets with analytes. Finally, this proposed ASEI-sweeping MEEKC method was able to detect trace level of catechins in food products that was not previously possible by a normal MEEKC method.

A radio frequency (rf) discharge has been utilized to study the decomposition of benzene. SEM inspection has shown that the size of soot particles ranged from 0.5 to several μm. The soot deposited on silicon wafers was analyzed by gas chromatography/mass spectrometry (GC/MS). It was shown that the main components of the soot are polyphenyls (biphenyl and terphenyls) and a trace amount of polycyclic aromatic hydrocarbons (PAHs). Acetylene and hydrogen have been detected by plasma diagnostics techniques using Fourier transform infrared (FTIR) and optical emission spectroscopic techniques. However, GC/MS analysis has shown that the relative yields of PAHs are much less than those of polyphenyls, which indicates that the conventional hydrogen abstraction-acetylene addition (HACA) model for soot formation is not applicable to the benzene plasma due to the reason of temperature. The rf power, the carrier gas flow-rate, the relative yields of polyphenyls, and plasma temperatures were correlated. The reaction pathways of benzene elimination and soot formation in plasma are discussed. This study has provided a new route to control the contamination due to PAHs.

Plasma interactions with chamber components and wafers in semiconductor manufacturing processes have been monitored with a fault detection technique. Not only can this diagnostic technique monitor the wafer and process chamber components qualities, but it also has potential in saving tremendous amounts of manufacturing costs and improving equipment productivity. We have discovered that the abnormality in certain plasma processing parameters detected in the early stages of a manufacturing line can have a strong correlation with the product yield. Possible reasons for the observed correlations are explained

We report the use of silver (Ag) colloids in the spectroscopic differentiation of methyl red (MR) isomers (o-MR, m-MR, p-MR) by fluorescence techniques. Under different pH conditions, the formation of MR–Ag complex has an impact on the fluorescence band shapes and peak position shift, which are distinctive between MR isomers. The fluorescence quenching between 400 and 414 nm accompanied by simultaneous enhancement between 510 and 541 nm changes with pH are closely related to energy transfer efficiency and the interaction between the MR isomers and the Ag surface.

Multi-walled carbon nanotubes (MWCNTs) were treated with a radio-frequency discharge. We found that MWCNTs showed opposite trends in electrical conductivity when treated with oxygen and hydrogen plasmas. MWCNTs showed enhanced electrical conductivity when placed at cathode with oxygen plasma treatment, whereas MWCNTs treated at positive column did not show such a trend. In contrast, the conductivity of MWCNTs dropped sharply with hydrogen plasma treatment. The measured conductivity trends of MWCNTs are correlated with observed Raman spectral shift. The possible mechanisms of the change in electrical conductivity in plasma-treated MWCNTs are discussed.

The drift of TEOS etch rate has been observed during MERIE oxide etch for the damascene process. The etch rate typically fluctuates between 5300 A/min and 6000 A/min. Studies using fluorocarbon-based chemistry show a normal TEOS etch rate when the chamber wall is heavily coated with polymer deposition. On the other hand, a lower etch rate appears when the chamber has less deposition. Hysteresis behavior has been observed during the etch rate of TEOS, as well as emission intensity trends of F, CFx(x=1~3), and SiF. From the observed emission intensity variation of F, CFx, and SiF, a model is proposed to explain the impact of chamber wall polymer deposition on the etch rate of TEOS. This model includes a mechanism of etch rate enhancement by embedding oxygen in the chamber wall polymer. From the correlation between etch rate and emission intensity, it clearly shows that F is directly responsible for the etch of TEOS. Compared to F, CFxplasma chemistry has a closer link to chamber wall polymer formation, but contributes less in the etch of TEOS.

Recently, Kapton (polyimide) has been used in the reduction of dust particles in plasma etching chambers. However, it is found that there is a limit of lifetime for Kapton in trapping particles. Beyond this time limit, particle contamination becomes serious and even causes defect on wafers. In this study, two plasma etching recipes were used to test the particle/polymer trapping efficiency of Kapton. A Fourier Transform Infrared (FTIR) spectrometer was used to examine the functional groups change of the Kapton surface after plasma etching. The increase of IR absorption of CFx (x = 2, 3) indicates the growth of fluorocarbon polymer on the Kapton surface. The Kapton surface was damaged as indicated by the change of C=O, -NH2, and C - H IR intensities. IR Spectroscopic data show that Kapton has a very good particle/polymer reduction efficiency when using high-polymer recipe but not very efficient with oxygen-rich recipe. It has drawn our attention that when testing metal contamination of the processed wafers using chambers with Kapton coating, the concentration of aluminum was always high as compared to those without using Kapton. It can be ascribed to the plasma damage of Kapton, as supported by the surface chemical analysis with energy dispersion spectroscopy (EDS). Data collected from FTIR and EDS are correlated to interpret the mechanisms of plasma damage of Kapton.

Metal oxide (MO) films (ZnO and CuO) were synthesized by hydrothermal methods and treated with hydrogen and oxygen plasmas. From uv-visible transmittance spectra, we have found that the optical band gaps of MO films blue-shifted with hydrogen plasma treatment, but red-shifted with oxygen plasma treatment. By alternating the treatment sequence of hydrogen and oxygen plasmas, the MO optical band gap values can be reversibly tuned with the tunable ranges as wide as 80 and 550 meV for ZnO and CuO, respectively. The mechanism for reversible tuning of optical property is proposed based on the results of optical emission, X-ray diffraction, and scanning electron microscopy characterization. Compared to conventional metal ion doping and high temperature annealing methods, the use of low-temperature hydrogen and oxygen plasmas is more environmentally friendly.

We report the fluorescence and surface-enhanced Raman scattering (SERS) analysis of methyl red (MR) isomers (o-MR, m-MR, p-MR) on silver (Ag) colloids at different pH conditions. The changes in simultaneous fluorescence quenching around 400 nm accompanied by enhancement around 540 nm with pH are closely related to energy transfer efficiency and the interaction between the carboxylic group and the Ag surface. The change of SERS signals with pH values can be ascribed to different adsorption orientations of MR on the Ag surface, from near flat (o-MR) to near perpendicular (p-MR).

The addition of HBr has been used with oxygen and chlorine-based chemistries to improve selectivity of polysilicon to gate oxide in gate-stack etching. As a consequence of high selectivity, polymer residues become a major factor in critical-dimension (CD) control. It is believed that the presence of HBr in the plasma is responsible for polymer formation. HBr and its polymer residues may induce surface reactions to form thin oxide layers. Such a phenomenon has been observed if the wafers are not treated with HF vapor immediately after reactive ion etching (RIE) of the gate. The magnitude of the oxide film growth is proportional to the delayed time between RIE and HF vapor treatment. The sidewall thickness of the gate is also affected by the time-delay effect. The growth of the oxide film on the sidewalls can eventually affect the gate CD, and thus the device performance. A simple reaction model for the growth of the oxide film is proposed to explain the correlation between delayed time and CD bias.

This study describes the ability of nanoscale liquid chromatography (nano-LC) coupled with UV or mass spectrometry (MS) for the simultaneous determination of eight common penicillin antibiotics (amoxicillin, ampicillin, penicillin G, penicillin V, oxacillin, cloxacillin, nafcillin and dicloxacillin) in commercial samples (pharmaceuticals, milk, porcine tissues (liver and kidney)) for the first time. Material types of the on-column polymeric frits (polystyrene-based and polymethacrylate-based monoliths) and the packed stationary phase materials (C8 and C18 particles of 3 microm) used in the nano-LC for the influence of penicillin separation were evaluated. The nano-LC and MS parameters such as the composition and flow rate of mobile phase, capillary voltage and temperature of dry gas were examined in order to acquire high separation resolution and detection sensitivity for penicillin analyses. Furthermore, a home-made in-line filter (a nylon membrane of 0.2 microm pore size), was first used to connect with the flow cell of high sensitivity UV detector or the nanoelectrospray needle in MS detection. The result indicated it could effectively improve the reproducibility of penicillin mass signals or prolong the lifetime of the flow cell. The nano-LC methods provided good quantitative precisions in the range of 89.5-111.2% for UV detection at 0.5 microg/mL penicillins, and 83. 1-94.9% for MS detection at 5 mcirog/L penicillins), respectively, as well as offered stable retention repeatabilities (the relative standard deviation (RSD) of retention time was lower 0.30% in both the UV and MS detections). Compared to other LC-MS methods, the proposed nano-LC systems provided better detection sensitivity for these penicillins (the limits of detection (LOD) was of 2.27-4.06 microg/L for UV mode, and 0.01-0.51 microg/L for MS mode) when either UV or MS detector was employed.

The prevention of charge-induced corrosion of tungsten vias after metal etch has been stud-ied with several types of commonly used wet chemical solutions and two kinds of dielectric film materials, silicon dioxide and silicon oxynitride. It was found that one of the solutions, leaving essentially no polymer residue on metal lines, could effectively prevent corrosion of tungsten vias. Other solutions either produced minor residues or severe sidewall erosion on metal lines. This study has shown that the combination of wet treatment with oxynitride as the dielectric charge shielding film was as effective as other conventional methods for preventing tungsten vias corrosion. However, for metal lines capped with silicon dioxide, significant sidewall ero-sion, surface roughness, and polymer residue were observed. Chemical reaction mechanisms are proposed for the preservation of tungsten vias after metal etch.

In this study, eight benzophenones, which are commonly used as UV filters in various cosmetics and plastics, were analyzed by capillary electrochromatography with a methacrylate ester-based monolithic column. The effects of the composition and pH of mobile phase, porogenic solvent ratio, and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) content on benzophenone separations were examined. For all benzophenones, separation performances were markedly improved in monolithic columns with larger 1-propanol ratio and higher AMPS content. Furthermore, a twofold increase in AMPS content almost reduced the separation time in half when a monolithic column had an adequately high surface area, i.e. monolithic column was produced in a higher ratio of 1-propanol. As well, the retention behaviors of these analytes in the monolithic column were strongly influenced by the level of acetonitrile in the mobile phase, and the pH of the mobile phase also had an apparent influence on separation resolution.

The drift of PECVD TEOS etch rate has been observed during MERIE oxide etch for damascene process. Etch rate typically fluctuates between 5300 Å/min. and 6000 Å/min. depending on chamber condition. Studies using fluorocarbon based chemistry show high TEOS etch rate when chamber wall is heavily coated with polymer deposition. Low etch rate appears when chamber has less deposition. Hysteresis behavior has been observed in TEOS etch rate and emission intensity trends ofF and CFx (x = 1 ∼ 3). From the correlation between etch rate and emission intensity, a model is proposed to explain the impact of chamber wall polymer deposition on TEOS etch rate. It clearly shows that F is directly responsible for the etch of TEOS. Comparing to F, CFx plasma chemistry has a closer link in chamber wall polymer formation, but less contribution in the etch of TEOS.

Carbonaceous dust particles have been synthesized from benzene using an rf glow discharge. Scanning electron microscope inspection revealed that the plasma-synthesized dust particles can be classified into two types. Shell-structured dust particles showed a wide size distribution from 3 to40 μm. The other type, with different degrees of aggregation, appeared to be dense and spherical with a very distinctive yellow color and size distribution from 100 nm to 2 μm. Analyses using micro-Raman and Fourier transform infrared microscopy indicated that the main components of the dust particles are polyphenyls and hydrogenated amorphous carbon (HAC). The luminescence background in Raman spectra and the infrared C–H stretching vibrational features observed around 3.4 μm for the dust particles are attributed to HAC. The formation mechanisms and spectroscopic characterization of carbonaceous dust particles are discussed.

Kapton (polyimide) has been considered a potential candidate for particle reduction in plasma etching chambers. However, it is found that the lifetime of kapton’s ability to trap particles is limited. Beyond this limit, particle contamination becomes serious. In this study, two plasma etching recipes were used to test the particle/polymer trapping efficiency of kapton. Fourier transform infrared (FTIR) and ultraviolet (UV)-visible emission spectroscopies were used to study plasma–kapton interactions. It is found that the functional groups change on the kapton surface as observed by IR has a strong link to the change of features in plasma emission spectra. The increase of IR absorption of CFx (x=2 and 3) indicates the growth of fluorocarbon polymer on the kapton surface. The kapton surface was damaged, as is indicated by the change of C=O, –NH2, and C–H IR intensities and the variation of CN and SiF peaks in UV-visible emission spectra. Spectroscopic data show that kapton has a very good particle/polymer r...