X-ray lithography two-state alignment system

Abstract

We present a novel alignment system for x-ray lithography. A linear Fresnel zone plate, defined on the mask, is used to focus a laser beam on a wafer mark (a series of dots). A fast electro-optic modulator is used to make the laser beam hop between two positions at the mark edges. The light diffracted by the periodic mark is measured at each position and a misalignment signal is originated when the mark is not illuminated equally in the two states. A signal that is proportional to the misalignment is generated when the error is within the alignment range ( ± 0.2 ,urn); outside that range a capture signal is present as long as the beam is on the mark, which would be typically 2-4,um wide. The method is highly sensitive with resolution in excess of 0.003 pm, has a wide capture range, no moving parts, and is suitable for real-time alignment during exposure. Sensitivity to gap changes is highly reduced, making the system ideal for synchrotron-based x-ray lithography aligners. 1995 J. Vac. Sci. Techno!. B 7 (6). Nov/Dec 1989 0734·2i1X/39/061995-05$01.00

First-principles calculations of the structural, phonon and thermal properties of ZnX (X = S, Se,Te) chalcogenides

“…The energy minima occurs at the values of a 0 = 5.371, 5.632 and 6.198 Å for ZnS, ZnSe and ZnTe, respectively. Our results are very close to other calculated values [31][32][33][34][35][36][37]. Also the calculated lattice constants agree well with the experimental values of 5.412, 5.667 and 6.103 Å, respectively, with the maximal error of 1.53%.…”

Theoretical Investigations of Some Physical Properties of HgX (X = S, Se and Te) Semiconducting Compounds

“…In Tables 1 to 3 displayed presently investigated few fundamental physical properties of HgS, HgSe and HgTe semiconducting compounds. The present results of total energy, bulk modulus and pressure derivative of the bulk modulus of HgX are close to the other such available theoretical data [1][2][3][4][5] and available experimental values. As far as our knowledge many physical properties of the HgX semiconductor compounds are not reported earlier in literature.…”

“…In spite of such importance of the materials such fundamental physical properties of HgX are very rarely studied materials, experimentally as well as theoretically. We theoretically investigated few such types of physical properties of the materials [1][2][3][4][5].…”