The chemical state change on the cresol-novolak photoresist surfaces was investigated using Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and some basic information of the chemical reactions caused by UV irradiation were obtained. The photoresist sample used in this study was a mixture of the base polymer of cresol-novolak resin and an additive which has naphtoquinonediazide as the photosensitive materials. This photoresist was coated on a Si wafer and then exposed to a 254 nm UV light over varied periods of time. It was clearly observed that the intensity of the peaks resulting from the scissioning of the chemical bonds and oxidation of the polymer backbone increased with the increase of exposure time. We also investigated the same samples using XPS and FT-IR. It was demonstrated that TOF-SIMS provides more sensitive information on the slight change of chemical state due to chemical bond scissioning and oxidation than XPS or FT-IR and that this technique is quite useful for the surface characterization of this kind of photoresist materials.
We developed a laboratory used laser-produced plasma X-ray source. Its characteristics concerning X-ray radiation were evaluated for Al, Ti, Fe and Nb targets in a wavelength region from 2 to 18 nm. The experimental results shows that the source has a brightness of 108∼109 photons/0.1 nm/rad2/mm2/shot at a laser intensity of 9×1012 W/cm2 and X-ray radiates with an energy conversion efficiency of about 4%. Futhermore, to demonstrate an application of the source to surface analysis, we constructed an X-ray diffractometer using the source and obtained X-ray diffraction profiles of a periodic Mo/Si multilayer structure.
The exchange reaction of formate (DCOO(a)) with gaseous formic acid (HCOOD) on Ni(110) was investigated below the decomposition temperature of formate (340 K) by means of time-resolved infrared reflection absorption spectroscopy (TR-IRAS). When HCOOD gas was admitted on DCOO(a)-covered Ni(110) at 300 K, the pre-adsorbed DCOO(a) was replaced by HCOO(a). Similar replacement was also observed by introducing H12 COOH gas onto H-13COO(a)-covered Ni(110). In such a temperature region from 240 to 300 K, no decomposition of formate was observed. Thus it was confirmed that those pre-adsorbed formate desorbed as formic acid accompanied by the transfer of hydrogen (deuterium) atom from post-introduced formic acid. The kinetics of the exchange reaction is investigated and the mechanism of that is also discussed.
Using spectral data processing techniques based mainly on the statistical theory, some attempts are made to develop a practical AES/XPS qualitative analysis software including how to make the precise peak detection and adequate transition line assignment, and to obtain the reasonable identification results finally. The present software is applied to some typical spectra data as well as the public VAMAS format data downloaded through the network from the Common Data Processing System (COMPRO). Good analysis results are generally obtained for simple samples, but still some problems remain for complex samples. We are trying to solve these problems one by one with the aid of statistical theory and/or heuristic knowledge of analysis experts.
We have studied theoretically the effect of gravity on the rough solid-liquid interface and have shown that its tension is enhanced by gravity when gas is adsorbed on it. As a result, the apparent equilibrium contact angle, which has been considered not to be influenced by gravity so far, can be raised by gravity for rough surfaces. The calculated dependence of contact angles on gravity under the ordinary conditions of the sessile drop method is large enough to detect by experiment. The observed asymmetric deviations of the Wenzel contact angles caused by the adsorption of gas at the solid-liquid interface and caused by the adsorption of liquid at the solid-gas interface are explained in terms of this gravitational effect.
Low voltage cathodoluminescent properties of the conventional CRT phosphors coated with In2O3 layer on the surface by the sol-gel method were investigated. The In2O3 conducting layer was crystallized by the heat treatment after the coating process. The luminance of the coated phosphor excited at low voltage region were extremely changed by the coating condition. Each phosphor has the optimum coating condition for the maximum luminance where the optimum molecular weight of In[OCH(CH3)2]3 for ZnS: Ag, Cl, ZnS: Cu, Al and Y2O2S: Eu is 3.7, 2.7 and 4.4wt%, respectively. The resistivity of the surface layer on the phosphor particle were decreased with increasing In[OCH(CH3)2]3 ratio. These results indicated that the decrease of the resistivity suppresses charging-up on the phosphor surface. It was estimated from the calculation of the thickness of the In2O3 conducting layer, that the In2O3 layer on any phosphors was approximately 10 nm at optimum coating condition of each phosphor. The luminance deterioration of phosphors by the electron beam irradiation were suppressed by the coating In2O3 layer. This fact suggests that the coating layer protected the decomposition of the phosphor surface.
Thin films of PbTiO3 (PT) were grown on various miscut (001) SrTiO3 (ST) substrates at 600°C by rf planar magnetron sputtering. The films on ST (miscut angle≤0.9°) included grain boundaries, but on ST (miscut angle≥1.7°) the surfaces were extremely smooth and comprised a periodic striped pattern which reflected the initial surface structure of the substrates. It was found that the critical miscut angle of substrate where the growth mode changes from twodimensional nucleation to step-flow was between 0.9°and 1.7°. TEM and XRD analysis showed that the PT thin films on miscut ST (miscut angle>≥1.7°) showed continuous single c-domain single crystal structure with three-dimensional epitaxy. The analysis of the c-axis tilt of the PT thin films also revealed that the film growth was governed by the stepflow growth.
Intensity changes of secondary ions from Poly (methyl methacrylate) (PMMA) with ion bombardment has been investigated by time-of-flight secondary ion mass spectrometry (TOF-SIMS). The “dose profiles” of several ion species, which were recorded as intensity variations versus primary ion dose, were observed. It was found that the profile have various tendencies over a range of ion dosage from 1012 to 2×1014 ions/cm2. By using a high mass resolution TOF-instrument, the closely located mass peaks such as C3H7+ and C2H3O+ at 43 amu were found to show different intensity change for different ion dosages. The relationship between the observed secondary ion intensities and bond breaking was discussed with referenced to the bond orders obtained by a semi-empirical MO calculation. It was found that the secondary ion formation reflects the bond strength of the analyzed polymer and the stability of the formed ions, and that the rearrangement processes may also have some influences on the detected ion intensities.
The structural change of formate on NiO(111) by irradiation of intense picosecond laser pulses of 1064 nm wavelength was studied by sum frequency generation (SFG) spectroscopy. The peak due to the bidentate formate (DCOO) was observed at 2160 cm-1 without the irradiation. When the laser pulses was introduced to the surface, the peak at 2160 cm-1 decreased in intensity and new peak appeared at 2190 cm-1. The newly observed peak was assigned to monodentate formate. The bidentate formate was found to be transformed to the monodentate formate by the transient temperature jump induced by the irradiation and the monodentate formate was regarded as an intermediate of thermal decomposition of formate.