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A laser terahertz emission system is proposed to investigate the catalytic metal/semiconductor interfaces of hydrogen sensors. Samples were fabricated by depositing a catalytic metal thin film on a semi-insulating silicon substrate. A femtosecond laser was used to radiate terahertz waves from the sample in a gas cell filled with a hydrogen and nitrogen gas mixture. The peak amplitude of the terahertz waves decreased with increasing hydrogen concentration. We also fabricated a metal-oxide-semiconductor field effect transistor hydrogen sensor, and compared its properties with the terahertz radiation properties. These results suggest that the laser terahertz emission system is a potential tool to investigate catalytic metal/semiconductor interfaces.

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Negative electron beam resists composed of a phenylcarbinol, poly(4-hydroxystyrene) (PHS), and an onium salt have been developed to define patterns below 100-nm. Five phenylcarbinols were evaluated as a precursor of a dissolution inhibitor (PDI) and a water generator (WAG) which induces anisotropic acid-diffusion. 1,3,5-tris(2-(2hydroxypropyl))benzene (Triol(3)) was found to be the best PDI and WAG among the phenylcarbinols evaluated. Acid-diffusion measurement in a resist film containing Triol(3) clearly shows that the acid-diffusion coefficient in the exposed region is larger than that of the unexposed region. A resist consisting of PHS, Triol(3), and diphenyliodonium triflate (DIT) exhibits enough resolution (80-nm L&S), sensitivity (5-pC/cm2 at 50kV), and critical dimension control to define 100-nm L&S patterns. Spectroscopic studies indicate that the acid-catalyzed 0-alkylation of PHS hydroxyl groups by Triol(3) is responsible for the resist insolubilization.

Acid-catalyzed intramolecular dehydration of phenylcarbinol is used to design highly sensitive negative resists for electron beam lithography. Of the phenylcarbinol resists evaluated in this study, the resist composed of 1,3-bis(a-hydroxyisopropyl)benzene (Diol-1), m/p-cresol novolak resin, and diphenyliodonium triflate (DIT) shows the best lithographic performance in terms of sensitivity and resolution. Fine O.25-j.tm line-and-space patterns were formed by using the resist containing Diol-1 with a dose of 3.6 .tC/cm2 in conjunction with a 50 kV electron beam exposure system.