Translational-symmetry alternating phase shifting mask grating mark used in a linear measurement model of lithographic projection lens aberrations

Abstract

A linear measurement model of lithographic projection lens aberrations is studied numerically based on the Hopkins theory of partially-coherent imaging and positive resist optical lithography (PROLITH) simulation. In this linearity model, the correlation between the mark's structure and its sensitivities to aberrations is analyzed. A method to design a mark with high sensitivity is proved and declared. By use of this method, a translational-symmetry alternating phase shifting mask (Alt-PSM) grating mark is redesigned with all of the even orders, AE3rd and AE5th order diffraction light missing. In the evaluation simulation, the measurement accuracies of aberrations prove to be enhanced apparently by use of the redesigned mark instead of the old ones.

Symmetric polarization aberration compensation method based on scalar aberration control for lithographic projection lens

“…The ultra-small RSS indicates that the linearity between BFS and retardance is excellent and the definition of the sensitivity is adoptable. The astigmatism and spherical aberrations are adjustable in advanced lithographic tools 13 , and the linear relationship between BFS and scalar even aberrations are verified by Qiu et al 14 . Therefore, a polarization aberration compensation method can be proposed by adjusting the scalar even aberrations to minimize the BFS caused by radially symmetric retardances.…”

Even aberration measurement of lithographic projection optics based on intensity difference of adjacent peaks in alternating phase-shifting mask image

“…The variation range of the partial coherence is 0.3-0.8. The accuracy of the aberration measurement can be estimated by [16,17] …”

Generalized formulations for aerial image based lens aberration metrology in lithographic tools with arbitrarily shaped illumination sources

“…The Zernike coefficients are calculated directly from the image displacements of the mark at multiple NA and partial coherence factor σ settings through a matrix of sensitivities, which is a function of the corresponding multiple NA/σ settings. Wang et al recently reported a series of TAMIS based techniques to improve the measurement accuracy of coma and even aberrations by optimization of the test marks using phase-shifting gratings [9][10][11][12]. Although the main advantage of TAMIS and its improved techniques is to present a simplified linear model in a simple form that can be fully characterized by a matrix of sensitivities, there is no compact analytical formulation for the matrix of sensitivities itself.…”