Imaging Characteristics of Multi-Phase-Shifting and Halftone Phase-Shifting Masks

Abstract

We have investigated the bonding nature and hole-electron Coulomb interaction U in thin C 60 films on Be(0001) surfaces using valence-band and corelevel photoemission, inverse photoemission, and near-edge x-ray absorption spectroscopies. The C 60 monolayer had strong covalent bonding with the Be substrate, producing a nearly insulating film, in contrast to a metallic overlayer due to charge transfer observed on many other metallic surfaces. The effect of polarization of surrounding molecules and the image potential decreases the energy gap and U , but the bonding-antibonding contribution increases the gap at the interface. The measured U in thin solid films agrees well with a model calculation using gas-phase values. The deduced hole-electron attraction on the surface is about 0.7 eV larger than the reported hole-hole repulsion determined by Auger spectroscopy. On the basis of the surface-solid difference, the newly estimated value of U for hole-hole correlation places doped C 60 compounds nearer the metallic side of a Mott transition.

Level-specific lithography optimization for 1-Gb DRAM

“…2. The three mask technologies are chromium-on-glass (COG), attenuated PSM [5], [6] and alternating PSM [4]. 4 COG is the standard mask technology in photolithography.…”

“…Thus alternating PSM's are sometimes classified as strong PSM's whereas attenuated PSM's are classified as 4 Other types of PSM's such as rim [8] and chromeless [9] are not considered because of design and practicality issues. 5 In an actual alternating PSM, mask topography effects cause transmittance imbalance [25] which can be partially or, in some cases, totally corrected [26], [27]. weak PSM's.…”

“…The possibility of combining various techniques further complicates the optimization problem. While the use of annular illumination [10] with attenuated PSM [5], [6] increases both the exposure latitude and depth-of-focus of dense lines and spaces compared with conventional lithography, combining annular illumination with alternating PSM [4] actually degrades the process latitude of the same features despite the improvement of using each technique individually [22].…”

A survey of advanced excimer optical imaging and lithography

“…[23 Since the calcium fluoride should be a single crystal, it is not easy to obtain large-diameter material. [3] The polishing should be different than the conventional one because of its crystal structure. Among the researchers, calcium fluoride has been one of the main topics these years.…”

Arrays of holes fabricated by electron-beam lithography combined with image reversal process using nickel pulse reversal plating

“…Although many different configurations of multiple beams can increase image contrast, only those that satisfy certain symmetry requirements preserve the large depth of field characteristic of two beams. To make fine hole patterns, application of optical lithographic techniques such as utilizing an attenuating phase shift mask is used to enhance the resolution, 8 however, the diameter formed by this approach is restricted to 0.20 m using the KrF excimer laser. Nakao et al 9 have used phase shift masks using KrF excimer laser as exposure light to fabricate 0.1 m dense holes.…”