Programmable uniformity correction by using plug-in finger arrays in advanced lithography system

Illumination integrated non-uniformity (IINU) is one of the key factors to determine the resolution and Critical Dimension Uniformity (CDU) which are important performance parameters in advanced lithography system. To further reduce the IINU, uniformity correction technology has been adopted. In this paper, an approach of programmable uniformity correction with higher flexibility and better correction capability is proposed. The method is composed of variable attenuation correction element arrays which are inserted into the edge of an illumination field to shield the energy through programming. Based on the proposed method, a programmable uniformity correction unit is applied to an illumination optical system. The simulation results show that the value of the corrected IINU reaches less than 0.25%, which satisfies the requirements of IINU in advanced lithography system, and the energy loss is less than 1.1%. It verifies the higher flexibility and better correction capability of the proposed method.