Light source and mask alternate optimization method based on Abbe vector imaging model

Abstract

The invention provides a light source and mask alternate optimization method based on an Abbe vector imaging model. According to the method, a graphics pixel value of a light source and transmissivity of an opening part and a light resistance part in a mask are set; variable matrixes omegaS and omegaM are established; a target function D is constructed to be a square of an Euler distance between a target graphics and an image in photoresist corresponding to the conventional light source and the conventional mask; and the alternate optimization process of the light source graphics and the mask graphics is guided according to the variable matrixes omegaS and omegaM and the target function D. Compared with the conventional method for independently optimizing the light source or the mask and synchronously optimizing the light source and the mask, the method has the advantage that the resolution of a photoetching system is effectively improved. Furthermore, the light source and the mask which are optimized by the method are applicable to small numerical apertures (NA) and NA which is more than 0.6. Moreover, according to gradient information of the optimized target function and a steepest speed reduction method, the efficiency for optimizing the light source graphics and the mask graphics is high.

Description

technical field [0001] The invention relates to a light source-mask alternate optimization method based on an Abbe (Abbe) vector imaging model, and belongs to the technical field of lithographic resolution enhancement. Background technique [0002] The current large-scale integrated circuits are generally manufactured using photolithography systems. The lithography system mainly includes four parts: illumination system (including light source and condenser), mask, projection system and wafer. The light emitted by the light source is focused by the condenser and then enters the mask, and the opening part of the mask transmits light; after passing through the mask, the light is incident on the wafer coated with photoresist through the projection system, so that the mask pattern is copied on the wafer. [0003] The current mainstream lithography system is the 193nm ArF deep ultraviolet lithography system. As the lithography technology node enters 45nm-22nm, the critical dimens...

AI Technical Summary

Problems solved by technology

However, the above method is based on the scalar imaging model of the lithography system, so it is not suitable for high NA lithography systems

At the same time, due to the different incident angles of light rays at different positions on the light source surface, their effects on the projection system are different, but the existing technology does not consider the difference in response of the projection system to the incident light rays of different points on the light source surface

Therefore, there is a large deviation between the aerial image obtained by the existing method and the actual situation, which in turn affects the optimization effect of the SESMO method

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