The main object of this paper is to investigate the root cause of CD change by neighboring field observed in KrF scanner (max. 0.70NA) and to measure the amount of stray light from neighboring field precisely. Line widths of gate pattern are measured at the isolated and surrounded field and the amount of CD change by neighboring field is found to be proportional to the clear ratio of mask. By exposing with special configuration, it is found that the line width is linearly decreased as the dose of neighboring field increases. From this linear dependency on doses of neighboring field, it is clear that non-negligible amount of light is scattered out into the adjacent field. The amount of this stray light level coming from neighboring field is obtained quantitatively by synthetic analysis of above result and double exposure to mimic background DC light by flare. About 1.2% of stray light from outside of the field is observed at the slit position close to the boundary of neighboring field. Disappearing pad test is also performed to measure the flare from exposure of field itself. Finally, it is obtained the distribution of total stray light - nominal flare plus flare from adjacent field - and it is found to be existed around 0.7% deviation of stray light across the slit.
High power near diffraction limited external cavity semiconductor tapered lasers that use a single-angled-facet input preamplifier are demonstrated for the first time. Four electrodes (three in the preamplifier region and one in the power section) on the device were implemented to investigate the switching contrast ratio of the output laser intensity. More than 1 W CW of power was obtained with a slope efficiency of 0.7 W/A, and close to 20 dB intensity contrast ratio was obtained by switching off two and three electrodes in the input ridge section. Also, more than 50 dB side-mode suppression ratio and 60 nm tuning bandwidth were obtained. These powers were found to be emitted in a near-diffraction- limited beam.
Hybrid DBR lasers composed of a semiconductor Fabry-Perot laser diode and a fiber Bragg grating have been demonstrated. In our approach, we use a single-angled facet laser diode and a conically lensed grating to obtain stable single-longitudinal mode operation over more than 85 mA current range with high side mode suppression ratio and narrow linewidth.
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