Keith R. Pope

Characterization of the reactive and dissociative behavior of transition metal oxide cluster ions in the gas phase

The reactive and dissociative behavior of molybdenum and tungsten oxide cluster ions has been studied in the gas phase using a triple quadrupole mass spectrometer. Cluster ions (MO3)n− were formed via a simple thermal desorption/electron capture negative ionization method, and their structures were characterized by collision-activated dissociation (CAD). Typically, the clusters fragment by losses of neutral (MO3) units. Reactions of the oxide cluster ions with ethylene oxide, cyclohexene oxide, ethylene sulfide cyclohexene sulfide, 2,3-butanedione, and 2,4-pentanedione were examined, and product ions were characterized by CAD. The clusters react with ethylene oxide by addition of ethylene oxide or net addition of oxygen, whereas the clusters react with ethylene sulfide via net addition of one or two sulfur atoms. Reactions of the clusters with the diones result in addition of one or two dione units, in some cases with dehydration.

Novel Si-based composite thin films for 193/157-nm attenuated phase-shift mask (APSM) applications

We have developed a novel Si-based composite thin film for attenuated phase shift mask(APSM) applications at 193/157 nm wavelength. The fabrication involved sputtering deposition, either with dual target or a single composite target. At 193 nm, these thin films show tunable optical transmission and good stability against long term radiation, common chemicals used to strip photoresist, and exhibit good dry etch selectivity to quartz. Specifically, a film with initial transmission of 5.72%,the total increase oftransmission was 0.27% for doses up to 5.4 kJ/cm2. Also, the increase of transmission was 0.19% after 60 mm of cleaning treatment in acid based solution (H2S04H20210:1 at 95°C). The dry etch selectivity over fused quartz was greater than 5:1. The transmission of the films at 193 nm can be tuned from 0 % to 20 % by varying the thin film composition, process gas flow and composition, and deposition pressure. This wide transmission window provides the possible extension down to 157 nm wavelength.