A non-topcoat (non-TC) resist is a photoresist that contains a hydrophobic additive, which segregates to the surface and
forms a layer to minimize surface free energy. The improvement of surface hydrophobicity and the suppression of resist
component leaching were confirmed by using this segregation layer. Compared to conventional topcoat process, it is
speculated that the use of non-TC resist will reduce the cost of lithographic materials, improve throughput, and will be
compatible for the scanning speed improvement of immersion scanners. One issue for the non-TC resist is the possibility
of increased defect generation compared to processes using topcoats. It is assumed that the high resist surface
hydrophobicity and the developer insolubility of the hydrophobic additive are main factors causing the increase in defect.
Therefore, it is important to work out solutions for reducing these defects to realize the non-TC resists. A process of
selectively removing the hydrophobic additive between exposure and development process for the purpose of defective
reduction of non-TC resist was investigated. Specifically, wet processing was performed to the wafer after exposure
using an organic solvent to dissolve the hydrophobic additive. As a result, defect count was reduced to less than 1/1000
with the effective removal of the segregation layer without affecting pattern size. These results prove the effectiveness of
the proposed process named 'selective segregation removal (SSR)' treatment in reducing defects for non-TC resists.
We summarize the on-orbit performance of the CCD detectors in the Suzaku X-ray Imaging Spectrometer during the first eight months of the mission. Gradual changes in energy scale, spectral resolution and other performance characteristics, mainly due to radiation exposure, are presented and compared with pre-launch expectations.
We report on a new photon-counting detector possessing unprecedented spatial resolution, moderate spectral resolution and high background-rejection capability for 0.1-100 keV X-rays. It consists of an X-ray charge-coupled device (CCD) and scintillator. The scintillator is directly deposited on the back surface of the X-ray CCD. Low-energy X-rays below 10 keV can be directly detected in the CCD. The majority of hard X-rays above 10 keV pass through the CCD but can be detected in the scintillator, generating visible light photons there. Since CCDs have a moderate detection effciency for visible light photons, they can be absorbed by the CCD. We evaluated the spectroscopic performance for hard X-rays at the synchrotron facility, SPring-8, and found a good linear relationship between the incident X-ray energy and the pulse height up to 80 keV. The on-axis image
of the hard X-ray telescope, supermirror, was measured by our device at 40 keV. A sharp core and the wing structure can be clearly imaged and high imaging capability of the SD-CCD can be demonstrated.
We present the current status of soft X-ray calibration of X-ray CCD cameras, X-ray Imaging Spectrometer (XIS), onboard Astro-E2. We perform soft X-ray calibration of four front illuminated (FI) CCD cameras and two back illuminated (BI) CCD cameras, among which four cameras will be selected to be installed on the satellite. The calibration aims to measure the quantum efficiency and re-distribution function of the CCDs as a function of incident X-ray energy. A soft X-ray spectrometer is used to measure these items. In addition, we employ a gas proportional counter and an XIS engineering unit as reference detectors for the quantum efficiency measurement. We describe how we calibrate the absolute quantum efficiency of the XIS using these instruments. We show some of the preliminary results of the calibration including quick look results of BI CCD cameras.