Research On Imaging Quality Compensation And Polarization Aberration Of Hyper Numerial Aperture Lithographic Lens

The core device for manufacturing large-scale integrated circuit is lithography machine,whose core unit is the lithographic lens.In order to approximately transfer the mask pattern to the photoresist,the image quality of the lithographic lens must meet extremely demanding requirements.If the optimal image quality compensation strategy is adopted in the manufacturing process of the lithographic lens,it is possible to loose the various tolerance requirements while ensuring the image quality,and thus reduce the manufacturing cost.The effect of the polarization state on imaging becomes unignorable when NA increases to a certain extent,thus the scalar aberration as well as polarization aberration should be considered when evaluating the image quality.In this paper,the image quality compensation strategy and polarization aberration of the NA 1.35 lithographic lens for 45 nm node in deep ultraviolet band are studied,aimming at the demestic industrial demand for the large scale integrated circuit.The main contents are as follows:1.The imaging theory of lithographic lens.The theory of scalar and vector imaging theory are studied.The vector imaging theory considers the polarization state of the imaging beam and the polarization aberration of the objective lens,so it is used to describe the imaging performance of the high NA lithographic lens.In this paper,a more comprehensive evaluation method for image quality is established,which include the wavefront aberration,distortion,and polarization aberration(diattenuation and retardance).2.The compensation strategy of imaging quality.In this paper,the methods of image quality compensation,including optical recalculation,computer aided alignment,surface figuring,deformable mirror,and thermal compensation technology,are studied systematically to compensate the imaging degradation of lithographic lens caused by the tolerances of optical material,manufacturing and assembly.Among them,the recalculation of component intervals is used to compensate for the one-dimensional material tolerances and machining tolerances,the recalculation of component rotation angle is used to compensate for two-dimensional tolerances such as refractive index uniformity tolerance and surfece tolerance,the computer-aided adjustment is mainly used to compensate for assembly tolerances,surface figuring is used to compensate for residual high order aberrations,and the combination of deformed mirror and thermal compensation technology is used to compensate for thermal aberration.In this paper,the mathematical models are established for various image quality compensation methods,and the corresponding program is written and simulated on a lithographic lens of NA 1.35.The results show that the image quality compensation method can recover the wavefront aberration and distortion to the design level.3.polarization aberration.In this paper,the polarization aberration of NA 1.35 lithographic lens is quantitatively analyzed,and the distribution law of polarized aberration in optical system is studied.A new polynomial,ie,field-orientation Zernike polynomials,is deduced.The polynomials are functions of the field and pupil coordinates,and can simultaneously characterize the distribution of polarized aberration on the field and the pupil.The items of the polynomials are orthogonal to each other on the unit circle field and the unit circle pupil.The field-orientation Zernike Polynomials are not only suitable for rotationally symmetric optical systems,but also for M-fold optical systems.In order to verify the correctness of the polynomial,a lithographic lens and a microscope objective are used for simulation,and the simulation results agree with the deduced theory.The research results of this paper can provide some useful guidance for the development of high NA lithographic lens.