In this work we demonstrate the power, speed and effectiveness of an automated rules-based approach for performing optical proximity correction. The approach applies to both conventional and phase-shifting mask layouts for optical lithography. Complex imaging, substrate and process phenomena can be folded into comparatively few rules parameters. Using simple arithmetic, these parameters pre-compensate the layout for the combined proximity effects. The rules consist of edge rules and corner rules for biasing feature edges and for adding sub-resolution assist features. This paper describes an integrated solution which includes rules parameter generation and fast, hierarchical rules application. Experimental results demonstrate improved edge placements and wider process latitude than for non-corrected layouts.

No abstract

The optical proximity effect can be a substantial fraction ofthe CD error budget. It is insufficient to determine the proximity effect as the difference between linewidth in an equal line/gap pattern with that of an isolated line. Other geometries may have greater proximity induced line-width errors. We present here a comprehensive, four parameter, analytic process to characterize actual proximity. It is shown that when individual, geometry-dependent line bias is applied line-width uniformity can be reduced to the range. Using the criteria, individual line bias expands the range ofexposure dose and depth of focus. INTRODUCTIONThe optical proximity effect is the result that densely packed lines do not print the same as isolated features13. However, it is not sufficient to just examine the equal line/gap and isolated line patterns. VLSI circuit layouts contain many line environments including the line next to or in-between large features, line pairs, line/gap arrays, etc. Each different occurrence ofthe minimum geometry line will print with a different line-width, sidewall slope or resist loss.

No abstract

Several theoretical treatments now exist in the literature for scattering of Rayleigh waves from topograhic features which are parallel to the incident wave front. These treatments, however, are not applicable to a large class of signal-processing devices in which the surface waves are scattered by inclined reflectors. A perturbational approach, similar to the earlier treatments but applicable to oblique incidence and to all perturbation orders, is presented. The first-order reflection coefficient of a Rayleigh wave from an inclined groove is computed. It is shown that an angle similar to a ’’Brewster’’ angle exists for which the surface wave reflection coefficient is zero. A prescription for applying the theory to anisotropic media is suggested. A clarification of the applicability of this and prior theories to steep-walled structures is given.