Study On Polarization Effects And Pattern Fidelity Technology In Hyper-NA Lithography

Pattern fidelity is a fundamental requirement for optical lithography in manufacturingintegrated circuit. With the development of lithography, pattern fidelity techniques arefacing more and more challenges in45nm lithography and beyond. This thesis studies thepattern fidelity techniques and the impact on pattern fidelity based on the45nmhyper-numerical aperture (NA) immersion lithography, and discusses the interactions inlithography performance among various impact factors.While the polarization states have been changed by the polarization effects, in thisthesis, more realistic non-uniform polarization illumination model is built and the impacton pattern fidelity is studied. The method to retrieve polarization aberration in CODE V isdeveloped, which is benefit in evaluating the lithography performance and could giveuseful feedback to lens designer in lens design phase.The individual impact of lithography-tool, process, and mask parameters on patternfidelity is studied. With simulating the impact of each individual parameter on criticaldimension (CD), different impact tendency could be find. The compensative effects couldbe utilized to improve the pattern fidelity, which enlighten us the parameters could beco-optimized together.The analytic and parametric source, mask, and NA co-optimization (SMNO) method isproposed for the first time. The accuracy of the approximate function model is evaluated.The co-impact of the source, mask, and NA on pattern fidelity could be jointly consideredin optimization. After co-optimization, good pattern fidelity could be realized within largeDOF under designated resolution. Analytic and parametric source, mask, and NA functionare used to build the SMNO method, which could effectively reduce the complexity of thesource and mask as well as improve the convergent efficiency. Co-optimization result showthat the SMNO method could realize even high pattern fidelity compared with source maskoptimization (SMO).The lithography-tool, process, and mask parameters co-optimization method is firstlyproposed to configure the lithography parameters in higher optimization dimensions. Thelithography co-optimization software is developed with the ability in optimizing more than70parameters. The compensative effects on pattern fidelity among lithography-tool,process, and mask could be used to extend the process window. A normalized method is developed to solve the problem that the large-scale parameters are obstructed by thesmall-scale parameters in multi-parameters optimization. After co-optimization, the DOFcould be enlarged by172.2%and118.05%for line-space and contact hole, respectively.What is more important, the two pattern fidelity techniques mentioned above can beapplied in real lithography-tools to compensating the polarization effect. The patternfidelity could be improved even though the projection lens with large polarizationaberration. While the flare, moving standard deviation, and the vibration of the wafer stagein real lithography-tool reduce the process window significantly, the multi-parametersco-optimization method could also improve the performance of the non-ideallithography-tool. The optimization method guarantees the lithography qualities of reallithography-tool.