In LP-CVD process, preparation of silicon nitride film with small tensile stress and low refractive index was investigated as a function of deposition temperature and reactant gas ratio (SiH2Cl2/NH3). The small stress film with low refractive index can be prepared easily by high temperature deposition. Applying the film to an x-ray mask membrane, a new silicon nitride single-layer x-ray mask with a large area window (such as 50 mm in diameter) and high transparency to visible light is realized. Using this mask, a submicron resist pattern (0.5 μm line and space) can be replicated easily by Si–K x-ray exposure system.
An exact method that malyticdly provides transfer matttrices in finite networks of quasicrystalline approximants of any dimensionality is discussed. We use these matrices in two ways: (a) to exactly determine the band stmcture of an infinite approximant network in analytical form; (b) to determine, also analytically, the quantum resistance of a finite strip of a network under appropriate boundary conditions. As a result of a subtle interplay between topology and phase interferences, we find that a strip of phason defeas along a special symmetry direction of a low 2D Penrose approximanf leads to the rigomus vanishing of the reflection coefficient for certain energies A similar behaviour appears in a low 3D approximant. This type of 'resonance' is discussed in connection with the gap structure of the corresponding ordered (undefected) system.
A new X-ray mask inspection method using replicated resist patterns is proposed. It is able to detect fatal opaque defects on the back surface of the mask and at the bottom of the hole pattern, in addition to those on the front surface. It can also ignore transparent defects on the mask. This method is useful even for defect detection on a single-die mask through die-to-die comparison. For the false process defects occurring during the replication process, a discrimination procedure using a 2-step die-to-die comparison is proposed. In inspection tests with SEMSpec, we investigate the relation between the detection sensitivity to small resist defects and the conductive-coating thickness on them.
Articles you may be interested in X-ray mask fabrication technology for 0.1 μm very large scale integrated circuits The x-ray mask fabrication process we developed can be used to make and maintain essentially defect-free masks consisting of Ta absorbers on SiN membrane. The surface of the deposited SiN substrates is polished to make them as smooth as possible. As Ta is chemically stable, mask fabrication processes are frequently followed with a wet-cleaning process using a strong acid solution. Inspection of resist patterns printed on a wafer confirms that there are less than 20 printable defects per mask, and there are no defects on the back surface. The inspection and repair are repeated until the mask is defect free. Defects caused by mask handling and x-ray exposure are immediately washed up by wet cleaning with strong acid. The resulting x-ray masks have been used in large-scale integrated circuits fabrication, and fully functional devices have been obtained.
Improvements and recent performance of a doublecrystal monochromator for a soft xray undulator at the Photon Factory Rev.Status of a beamline for a 60period soft xray undulator in the low emittance operation of the Photon Factory storage ring Rev.A soft x-ray microscope using Fresnel zone plates as optical imaging elements was installed at the Photon Factory. It makes use ofundulator radiation as a source of soft x rays ranging from 2.0 to 3.0 nm in wavelength. The optical system was designed to match to the undulator radiation. A performance test was made at 2.66 nm by various pitches of transmission gratings. Those magnified images were taken with a magnification of230 and exposure times of about lOs. The modulation transfer function was measured over the spatial frequency up to 3300 Ip/mm. Further, magnified images of some biological specimens were obtained.
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