Electron beam nanoprocessing of a carbon nanotube film using a variable pressure scanning electron microscope.

We demonstrate a novel method of processing carbon nanotubes using a variable pressure scanning electron microscope. Lines were processed in a nanotube film by electron beam irradiation in oxygen gas and nitrogen gas. The processing mechanism can be explained in terms of gas ion sputtering and chemical reaction. In this experiment, the narrowest line width of 120 nm was achieved in a nitrogen atmosphere.

SPM system for semiconductor device applications.

Recently, scanning probe microscopy (SPM) is widely used for development of semiconductor devices. One of the important functions of SPM is high resolution topography, such as shape of the nanoscale devices and surface roughness of the films. Additionally, SPM can measure the electronic structure of the nanoscale-devices. SPM system for thin films was developed to characterize the thin films for device applications.First, SPM system which can be apply short pulses to the sample holder is constructed to evaluate the electronic response of the thin film without using complex patterning on the Si wafer as shown in Fig. 1. Current design rule of the semiconductor devices is around 20 nm. The dimension of the devices are close to the probe radius of conductive SPM probes. The instrument was designed to characterize not only the static properties of nanoscale devices, but also the dynamic electronic properties. Shortest pulses which can be applied to the sample without destroying waveform were less than 50 nS. Time response of the current amplifier is ranging from 50 nS to 200 nS depending on the trans-impedance gains. The conditions (time and dimension) are similar to the active devices on the chip in the circuit. Thus, dynamic electronic properties of the thin films can be tested on a film without fabricating to the nanoscale devices. It is very helpful to optimizing the depositing conditions, such as sputtering parameters, of the thin film for semiconductor devices. For example, the system is used to optimize the film qualities for resistive memories [1].jmicro;63/suppl_1/i13-a/DFU091F1F1DFU091F1Fig. 1.Conductive probe microscopy, which is compatible to the pulse signals ranging to 50nS. The second function of the SPM system is the reproducible roughness measurement. Roughness of the film is also important for optimizing the depositing conditions of the thin film. Virtual reference probe method was developed for removing the variations of the SPM probes [2]. One of the biggest problems of SPM roughness measurement is the huge variations of the SPM probe apexes. The method is to normalizing the probe to the largest probe used in the measurements, after characterizing the probe shape with suitable reference artefact [3,4]. Image reconstruction, such as erosion and dilation process is used for the analysis.In this presentation, we will introduce the SPM system developed for semiconductor device applications. The SPM system also includes function to characterize the nanoscale contaminants on the Si wafer. AcknowledgmentI would like to thanks Ms. Ito and Dr. C.M. Wang in AIST for discussions. This study was partially supported from MEXT.

Cathodoluminescence investigation of organic materials.

Cathodoluminescence (CL) properties of various kinds of organic material were investigated for the purpose of staining biological specimens and obtaining CL images. Several kinds of organic light emitting device (OLED) material exhibited CL. The europium complex, Eu(dbm)3(phen), showed the strongest CL signal and was chemically modified for biological staining. However, the CL intensity from the stained biological specimen was too weak to build CL images. We discussed the CL properties of organic materials considering their chemical structure and charge distribution in the molecules.

Cathodoluminescence imaging for identifying uptaken fluorescence materials in Kupffer cells using scanning electron microscopy.

Cathodoluminescence (CL) is the light that is emitted from a material irradiated by an electron beam. The present study was undertaken to show the applicability to biological studies of a scanning electron microscope (SEM) equipped with a high-sensitive cathodoluminescence detection system. For this purpose, we injected inorganic fluorescent powders (P43) suspended in phosphate buffered saline into rat blood circulation, fixed the animals with glutaraldehyde within a day, and observed the hepatic tissues with a SEM. Our instrument enabled the simultaneous collection of both secondary electron (SE) and CL images of these tissues. Backscattered electron (BSE) images of the same portion were also able to be obtained with this microscope. SE and BSE images clearly showed the three-dimensional structure of the hepatic tissues including hepatocytes, Kupffer cells, Ito cells, and sinusoidal epithelial cells, while CL images visualized cathodoluminescence signals emitted from P43 as bright spots. We observed non-coated tissues under a low-vacuum condition and metal-coated tissues under a high-vacuum condition, and found that the high-vacuum observation of metal-coated tissues provided high quality CL images of P43 in the Kupffer cells. The superimposition of the CL images onto the corresponding SE or BSE images revealed that bright spots in the CL images were produced by the fluorescent powders uptaken by Kupffer cells. These findings indicate that the detection of CL as well as SE or BSE signals by SEM all provide us with useful information on the distribution of fluorescent tracers in tissues and cells in three-dimensional images.