| The objective lens system is an important part of the lithography machine,and the objective image aberration is an important factor affecting the line width of the integrated circuit.The introduction of active deformation by modifying optical components is a means of compensating for aberrations,and the use of reflective deformable mirrors is a cutting-edge design solution.The reflective deformable mirror mainly adopts the mechanical piezoelectric ceramic multi-point driving scheme,which has the advantages of large deformation and fast response,but has a large component high-order Zernike aberration,and high cost and complex control algorithm.The thermally driven reflective anamorphic mirror is a new solution that has appeared in recent years.It has the advantages of less additional high-order aberration components,relatively simple control,simplified structure and low cost,and is suitable for low-frequency and low-order aberration compensation applications.Thesis carried out the optical analysis and thermal coupling analysis of a lithography objective lens system.By extracting the monochromatic aberration and the thermal deformation of the individual objective lens spherical surface under a certain working condition,used the Zernike polynomial decomposition,and the general working condition is obtained by combining with the relevant literature research.The following conclusion is that the image aberrations of the lithographic objective consist mainly of low-order aberrations.Thesis carried out the design of the mirror body structure.By means of theoretical analysis and simulation test,heat flow load is applied to obtain the surface shape change of the reflective deformable mirror.By exploring the thermal deformation model of free warping,according to the thermal diffusion analysis,thesis found the cause of the thermal distortion phenomenon in the free warping state,and based on this,the warping deformation scheme of the mirror body under various constraints is tried,and finally determined through simulation.The mirror body structure scheme with PMMA embedded in fused silica is adopted,and it is determined that this scheme has the controllable characteristic that the mirror surface deformation and the bottom surface heat flux density distribution have a relatively obvious correspondence.Thesis focuses on the problem of fitting low-order Zernike aberrations to thermally driven mirror surface deformation.A parallel search algorithm modified based on the steepest descent method is proposed,which uses numerical means to replace the search direction and step length in the steepest descent method respectively.Using COMSOL Live Link?for MATLAB?platform,built a calculation model for iterative search calculation.And it is confirmed that when the size of the PMMA part isΦ70mm and the thickness is 3mm,with the size of the fused silica part isΦ90mm and the thickness is4mm,the result of fitting the Zernike polynomial 1-5 order surface shape in the centerΦ30mm part can be obtained,and the RMS result is less than 0.15um.Thesis designed and built the laser driving optical path of the thermally driven deformable mirror.According to the relevant parameters obtained from the simulation,the laser beam modulation optical path and the optical pattern information modulation optical path are designed,and the relevant components are purchased to build a driving platform.Clear imaging of distribution designs.In this thesis,the light distribution changes of the driving optical path in the iterative process are simulated,and part of the process of the light source modulation changes in the simulation iterative process is recorded. |
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