Translator Disclaimer
22 October 2010 Application and influence of aspheric surfaces in lithographic objectives design
Author Affiliations +
In semiconductor industry, exposure tools have been improved in resolution. 193 nm lithography is one of the promising technologies for the fabrication of critical dimension from 100 to 32 nm. The optical performance of projection lens is the key factor to realize high resolution pattern. This paper presents the design process of a refractive lithography projection lens utilizing aspheric surfaces. The objective, as built, has a numerical aperture of 0.75, a maximum astigmatism of 30 nm and a total focal plane deviation of 45 nm. With the assistant of resolution enhancement technology, image resolution can reach 90 nm. Aspheric surfaces can be used to correct aberrations, to make optical systems more compact, and in some cases to reduce cost. Systems with and without aspheric surfaces are compared in the paper so as to find their differences in aberrations and configuration. We found that aspheric surfaces dramatically decrease the RMS wavefront error from 3 nm to 1 nm. Differ in position of aspheres can be used to correct aperture dependent aberrations (spherical aberration), and to correct field dependent aberrations (distortion and field curvature). We explored the connection between position of aspheres and different aberrations by APS (Aspheric surfaces selecting factor). Aspheric surfaces also make the system more applicable by reducing the system volume and leaving proper edge thickness for mechanical structure.
© (2010) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Bin Ma, Lin Li, Yifan Huang, Chang Jun, Baolin Du, and Xing Han "Application and influence of aspheric surfaces in lithographic objectives design", Proc. SPIE 7657, 5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Design, Manufacturing, and Testing of Micro- and Nano-Optical Devices and Systems, 76570A (22 October 2010);

Back to Top