Rigorous 3D process and device simulation has been applied to transistors with curved channel shapes that are inevitable due to the optical proximity effects. The impact of channel curvature on the transistor performance has been benchmarked using the universal Ion/Ioff coordinates. Systematic study of the different non-rectangular channel shapes included straight lines at an angle different than 90 degrees and concave and convex shapes with different curvature radii. The study reveals that any deviation from the ideal rectangular shape affects transistor performance. The amount of enhancement or degradation depends on particular shape, with on current, threshold voltage, and off current responding very differently to the same shape variation. The type and amount of performance variation is very different for the distorted channel length (i.e. poly gate shape) vs distorted channel width (i.e. active layer shape). Degradation of over 50% in the on current at a fixed off current has been observed in the most unfavorable cases for each of the two critical mask layers. On the other hand, a desirable over 3x off current reduction at a fixed on current can be achieved by selecting a beneficial channel shape.

Date Published: 12 March 2009
PDF: 10 pages
Proc. SPIE 7275, Design for Manufacturability through Design-Process Integration III, 72751B (12 March 2009);

Published in SPIE Proceedings Vol. 7275:
Design for Manufacturability through Design-Process Integration III
Vivek K. Singh; Michael L. Rieger, Editor(s)