25 nm Wide Silicon Trench Fabrication by Edge Lithography

概要

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Very narrow SiO2 line patterns are obtained by a new edge lithography technique and narrow silicon trenches are fabricated using the SiO2 line patterns. A line pattern with a width below 20 nm is successfully fabricated. Its line height is 180 nm and the aspect ratio exceeds 9. The line is rippled because of the high aspect ratio. A circular line of 40 nm width and 400 nm height is obtained without a ripple. The narrow SiO2 patterns are transferred to a Cr pattern by a lift-off process. Silicon is etched by an improved switching process using a Cr pattern mask. The etching rate decreases as the opening width decreases below 500 nm. Very narrow trenches of 25 nm width are fabricated. The side wall profile is vertical when the trench depth is 325 nm. Its aspect ratio is 13. However, bowing is observed in the side wall profile for a trench depth of 1000 nm.
2011-08-25