Lithography performance and simulation accuracy at different polarization states for sub 40nm node

The imaging performances of XY linear and TE Azimuthal polarization were compared by thin mask approximation and rigorous 3D mask simulation. The simulations were performed for 40nm and 44nm half pitch patterns with a hyper NA (1.35) system. Each polarization state was assumed to have a parametric DOP (degree of polarization) value that was set to 0.95. Rotated dipole illuminators of several angles were used for the associated tilted patterns to see the imaging impact by IPS (intensity in the preferred state of polarization) change in the process with XY linear polarization that has a fixed angle of polarization. The difference in performance between two polarization modes were compared by NILS and DOF margin. Additionally, the imaging quality of BIM (binary intensity mask) with polarization beam was studied to that of att-PSM at given process conditions. Two types of available BIM masks of different thickness were applied to simulation to understand 3D mask simulation impact on the imaging contrast and process margin. The estimation of two-diffraction beam balance was performed to explain the imaging simulation as well. The polarization sensitivities of NILS and CD change by DOP were found for each feature with given exposure conditions. The main purpose of this study is to understand how much overestimation or underestimation of conventional thin mask simulation could be combined in the process simulation by comparing rigorous 3D mask consideration.